Evaluation of analytical performance based on partial order methodology.

PubMed

Carlsen, Lars; Bruggemann, Rainer; Kenessova, Olga; Erzhigitov, Erkin

2015-01-01

Classical measurements of performances are typically based on linear scales. However, in analytical chemistry a simple scale may be not sufficient to analyze the analytical performance appropriately. Here partial order methodology can be helpful. Within the context described here, partial order analysis can be seen as an ordinal analysis of data matrices, especially to simplify the relative comparisons of objects due to their data profile (the ordered set of values an object have). Hence, partial order methodology offers a unique possibility to evaluate analytical performance. In the present data as, e.g., provided by the laboratories through interlaboratory comparisons or proficiency testings is used as an illustrative example. However, the presented scheme is likewise applicable for comparison of analytical methods or simply as a tool for optimization of an analytical method. The methodology can be applied without presumptions or pretreatment of the analytical data provided in order to evaluate the analytical performance taking into account all indicators simultaneously and thus elucidating a "distance" from the true value. In the present illustrative example it is assumed that the laboratories analyze a given sample several times and subsequently report the mean value, the standard deviation and the skewness, which simultaneously are used for the evaluation of the analytical performance. The analyses lead to information concerning (1) a partial ordering of the laboratories, subsequently, (2) a "distance" to the Reference laboratory and (3) a classification due to the concept of "peculiar points". Copyright © 2014 Elsevier B.V. All rights reserved.

40 CFR 141.803 - Coliform sampling.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Coliform sampling. 141.803 Section 141...) NATIONAL PRIMARY DRINKING WATER REGULATIONS Aircraft Drinking Water Rule § 141.803 Coliform sampling. (a) Analytical methodology. Air carriers must follow the sampling and analysis requirements under this section...

40 CFR 141.803 - Coliform sampling.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Coliform sampling. 141.803 Section 141...) NATIONAL PRIMARY DRINKING WATER REGULATIONS Aircraft Drinking Water Rule § 141.803 Coliform sampling. (a) Analytical methodology. Air carriers must follow the sampling and analysis requirements under this section...

New analytical methodology for analysing S(IV) species at low pH solutions by one stage titration method (bichromatometry) with a clear colour change. Could potentially replace the state-of-art-method iodometry at low pH analysis due higher accuracy

PubMed Central

Galfi, Istvan; Virtanen, Jorma; Gasik, Michael M.

2017-01-01

A new, faster and more reliable analytical methodology for S(IV) species analysis at low pH solutions by bichromatometry is proposed. For decades the state of the art methodology has been iodometry that is still well justified method for neutral solutions, thus at low pH media possess various side reactions increasing inaccuracy. In contrast, the new methodology has no side reactions at low pH media, requires only one titration step and provides a clear color change if S(IV) species are present in the solution. The method is validated using model solutions with known concentrations and applied to analyses of gaseous SO2 from purged solution in low pH media samples. The results indicate that bichromatometry can accurately analyze SO2 from liquid samples having pH even below 0 relevant to metallurgical industrial processes. PMID:29145479

PCB congener analysis with Hall electrolytic conductivity detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edstrom, R.D.

1989-01-01

This work reports the development of an analytical methodology for the analysis of PCB congeners based on integrating relative retention data provided by other researchers. The retention data were transposed into a multiple retention marker system which provided good precision in the calculation of relative retention indices for PCB congener analysis. Analytical run times for the developed methodology were approximately one hour using a commercially available GC capillary column. A Tracor Model 700A Hall Electrolytic Conductivity Detector (HECD) was employed in the GC detection of Aroclor standards and environmental samples. Responses by the HECD provided good sensitivity and were reasonablymore » predictable. Ten response factors were calculated based on the molar chlorine content of each homolog group. Homolog distributions were determined for Aroclors 1016, 1221, 1232, 1242, 1248, 1254, 1260, 1262 along with binary and ternary mixtures of the same. These distributions were compared with distributions reported by other researchers using electron capture detection as well as chemical ionization mass spectrometric methodologies. Homolog distributions acquired by the HECD methodology showed good correlation with the previously mentioned methodologies. The developed analytical methodology was used in the analysis of bluefish (Pomatomas saltatrix) and weakfish (Cynoscion regalis) collected from the York River, lower James River and lower Chesapeake Bay in Virginia. Total PCB concentrations were calculated and homolog distributions were constructed from the acquired data. Increases in total PCB concentrations were found in the analyzed fish samples during the fall of 1985 collected from the lower James River and lower Chesapeake Bay.« less

Low-Level Analytical Methodology Updates to Support Decontaminant Performance Evaluations

DTIC Science & Technology

2011-06-01

from EPDM and tire rubber coupon materials that were spiked with a known amount of the chemical agent VX, treated with bleach decontaminant, and...to evaluate the performance of bleach decontaminant on EPDM and tire rubber coupons. Dose-confirmation or Tool samples were collected by delivering...components • An aging or damaged analytical column • Dirty detector • Other factors related to general instrument and/or sample analysis performance

Sample Size and Power Estimates for a Confirmatory Factor Analytic Model in Exercise and Sport: A Monte Carlo Approach

ERIC Educational Resources Information Center

Myers, Nicholas D.; Ahn, Soyeon; Jin, Ying

2011-01-01

Monte Carlo methods can be used in data analytic situations (e.g., validity studies) to make decisions about sample size and to estimate power. The purpose of using Monte Carlo methods in a validity study is to improve the methodological approach within a study where the primary focus is on construct validity issues and not on advancing…

Assessment of pesticide contamination in soil samples from an intensive horticulture area, using ultrasonic extraction and gas chromatography-mass spectrometry.

PubMed

Gonçalves, C; Alpendurada, M F

2005-03-15

In order to reduce the amount of sample to be collected and the time consumed in the analytical process, a broad range of analytes should be preferably considered in the same analytical procedure. A suitable methodology for pesticide residue analysis in soil samples was developed based on ultrasonic extraction (USE) and gas chromatography-mass spectrometry (GC-MS). For this study, different classes of pesticides were selected, both recent and old persistent molecules: parent compounds and degradation products, namely organochlorine, organophosphorous and pyrethroid insecticides, triazine and acetanilide herbicides and other miscellaneous pesticides. Pesticide residues could be detected in the low- to sub-ppb range (0.05-7.0mugkg(-1)) with good precision (7.5-20.5%, average 13.7% R.S.D.) and extraction efficiency (69-118%, average 88%) for the great majority of analytes. This methodology has been applied in a monitoring program of soil samples from an intensive horticulture area in Póvoa de Varzim, North of Portugal. The pesticides detected in four sampling programs (2001/2002) were the following: lindane, dieldrin, endosulfan, endosulfan sulfate, 4,4'-DDE, 4,4'-DDD, atrazine, desethylatrazine, alachlor, dimethoate, chlorpyrifos, pendimethalin, procymidone and chlorfenvinphos. Pesticide contamination was investigated at three depths and in different soil and crop types to assess the influence of soil characteristics and trends over time.

State of the art of environmentally friendly sample preparation approaches for determination of PBDEs and metabolites in environmental and biological samples: A critical review.

PubMed

Berton, Paula; Lana, Nerina B; Ríos, Juan M; García-Reyes, Juan F; Altamirano, Jorgelina C

2016-01-28

Green chemistry principles for developing methodologies have gained attention in analytical chemistry in recent decades. A growing number of analytical techniques have been proposed for determination of organic persistent pollutants in environmental and biological samples. In this light, the current review aims to present state-of-the-art sample preparation approaches based on green analytical principles proposed for the determination of polybrominated diphenyl ethers (PBDEs) and metabolites (OH-PBDEs and MeO-PBDEs) in environmental and biological samples. Approaches to lower the solvent consumption and accelerate the extraction, such as pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, are discussed in this review. Special attention is paid to miniaturized sample preparation methodologies and strategies proposed to reduce organic solvent consumption. Additionally, extraction techniques based on alternative solvents (surfactants, supercritical fluids, or ionic liquids) are also commented in this work, even though these are scarcely used for determination of PBDEs. In addition to liquid-based extraction techniques, solid-based analytical techniques are also addressed. The development of greener, faster and simpler sample preparation approaches has increased in recent years (2003-2013). Among green extraction techniques, those based on the liquid phase predominate over those based on the solid phase (71% vs. 29%, respectively). For solid samples, solvent assisted extraction techniques are preferred for leaching of PBDEs, and liquid phase microextraction techniques are mostly used for liquid samples. Likewise, green characteristics of the instrumental analysis used after the extraction and clean-up steps are briefly discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

RCRA Facility investigation report for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 5, Technical Memorandums 06-09A, 06-10A, and 06-12A

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

This report provides a detailed summary of the activities carried out to sample groundwater at Waste Area Grouping (WAG) 6. The analytical results for samples collected during Phase 1, Activity 2 of the WAG 6 Resource Conservation and Recovery Act Facility Investigation (RFI) are also presented. In addition, analytical results for Phase 1, activity sampling events for which data were not previously reported are included in this TM. A summary of the groundwater sampling activities of WAG 6, to date, are given in the Introduction. The Methodology section describes the sampling procedures and analytical parameters. Six attachments are included. Attachmentsmore » 1 and 2 provide analytical results for selected RFI groundwater samples and ORNL sampling event. Attachment 3 provides a summary of the contaminants detected in each well sampled for all sampling events conducted at WAG 6. Bechtel National Inc. (BNI)/IT Corporation Contract Laboratory (IT) RFI analytical methods and detection limits are given in Attachment 4. Attachment 5 provides the Oak Ridge National Laboratory (ORNL)/Analytical Chemistry Division (ACD) analytical methods and detection limits and Resource Conservation and Recovery Act (RCRA) quarterly compliance monitoring (1988--1989). Attachment 6 provides ORNL/ACD groundwater analytical methods and detection limits (for the 1990 RCRA semi-annual compliance monitoring).« less

Analytical aspects of plant metabolite profiling platforms: current standings and future aims.

PubMed

Seger, Christoph; Sturm, Sonja

2007-02-01

Over the past years, metabolic profiling has been established as a comprehensive systems biology tool. Mass spectrometry or NMR spectroscopy-based technology platforms combined with unsupervised or supervised multivariate statistical methodologies allow a deep insight into the complex metabolite patterns of plant-derived samples. Within this review, we provide a thorough introduction to the analytical hard- and software requirements of metabolic profiling platforms. Methodological limitations are addressed, and the metabolic profiling workflow is exemplified by summarizing recent applications ranging from model systems to more applied topics.

Evaluation of analytical methodology for hydrocarbons in high pressure air and nitrogen systems. [evaluation of methodology

NASA Technical Reports Server (NTRS)

1977-01-01

Samples of liquid oxygen, high pressure nitrogen, low pressure nitrogen, and missile grade air were studied to determine the hydrocarbon concentrations. Concentration of the samples was achieved by adsorption on a molecular sieve and activated charcoal. The trapped hydrocarbons were then desorbed and transferred to an analytical column in a gas chromatograph. The sensitivity of the method depends on the volume of gas passed through the adsorbent tubes. The value of the method was verified through recoverability and reproducibility studies. The use of this method enables LOX, GN2, and missile grade air systems to be routinely monitored to determine low level increases in specific hydrocarbon concentration that could lead to potentially hazardous conditions.

Analytical control test plan and microbiological methods for the water recovery test

NASA Technical Reports Server (NTRS)

Traweek, M. S. (Editor); Tatara, J. D. (Editor)

1994-01-01

Qualitative and quantitative laboratory results are important to the decision-making process. In some cases, they may represent the only basis for deciding between two or more given options or processes. Therefore, it is essential that handling of laboratory samples and analytical operations employed are performed at a deliberate level of conscientious effort. Reporting erroneous results can lead to faulty interpretations and result in misinformed decisions. This document provides analytical control specifications which will govern future test procedures related to all Water Recovery Test (WRT) Phase 3 activities to be conducted at the National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC). This document addresses the process which will be used to verify analytical data generated throughout the test period, and to identify responsibilities of key personnel and participating laboratories, the chains of communication to be followed, and ensure that approved methodology and procedures are used during WRT activities. This document does not outline specifics, but provides a minimum guideline by which sampling protocols, analysis methodologies, test site operations, and laboratory operations should be developed.

Use of Cdse/ZnS quantum dots for sensitive detection and quantification of paraquat in water samples.

PubMed

Durán, Gema M; Contento, Ana M; Ríos, Ángel

2013-11-01

Based on the highly sensitive fluorescence change of water-soluble CdSe/ZnS core-shell quantum dots (QD) by paraquat herbicide, a simple, rapid and reproducible methodology was developed to selectively determine paraquat (PQ) in water samples. The methodology enabled the use of simple pretreatment procedure based on the simple water solubilization of CdSe/ZnS QDs with hydrophilic heterobifunctional thiol ligands, such as 3-mercaptopropionic acid (3-MPA), using microwave irradiation. The resulting water-soluble QDs exhibit a strong fluorescence emission at 596 nm with a high and reproducible photostability. The proposed analytical method thus satisfies the need for a simple, sensible and rapid methodology to determine residues of paraquat in water samples, as required by the increasingly strict regulations for health protection introduced in recent years. The sensitivity of the method, expressed as detection limits, was as low as 3.0 ng L(-1). The lineal range was between 10-5×10(3) ng L(-1). RSD values in the range of 71-102% were obtained. The analytical applicability of proposed method was demonstrated by analyzing water samples from different procedence. Copyright © 2013 Elsevier B.V. All rights reserved.

Advanced Analytical Methodologies Based on Raman Spectroscopy to Detect Prebiotic and Biotic Molecules: Applicability in the Study of the Martian Nakhlite NWA 6148 Meteorite

NASA Astrophysics Data System (ADS)

Madariaga, J. M.; Torre-Fdez, I.; Ruiz-Galende, P.; Aramendia, J.; Gomez-Nubla, L.; Fdez-Ortiz de Vallejuelo, S.; Maguregui, M.; Castro, K.; Arana, G.

2018-04-01

Advanced methodologies based on Raman spectroscopy are proposed to detect prebiotic and biotic molecules in returned samples from Mars: (a) optical microscopy with confocal micro-Raman, (b) the SCA instrument, (c) Raman Imaging. Examples for NWA 6148.

Rapid, specific determination of iodine and iodide by combined solid-phase extraction/diffuse reflectance spectroscopy

NASA Technical Reports Server (NTRS)

Arena, Matteo P.; Porter, Marc D.; Fritz, James S.

2002-01-01

A new, rapid methodology for trace analysis using solid-phase extraction is described. The two-step methodology is based on the concentration of an analyte onto a membrane disk and on the determination by diffuse reflectance spectroscopy of the amount of analyte extracted on the disk surface. This method, which is adaptable to a wide range of analytes, has been used for monitoring ppm levels of iodine and iodide in spacecraft water. Iodine is used as a biocide in spacecraft water. For these determinations, a water sample is passed through a membrane disk by means of a 10-mL syringe that is attached to a disk holder assembly. The disk, which is a polystyrene-divinylbenzene composite, is impregnated with poly(vinylpyrrolidone) (PVP), which exhaustively concentrates iodine as a yellow iodine-PVP complex. The amount of concentrated iodine is then determined in only 2 s by using a hand-held diffuse reflectance spectrometer by comparing the result with a calibration curve based on the Kubelka-Munk function. The same general procedure can be used to determine iodide levels after its facile and exhaustive oxidation to iodine by peroxymonosulfate (i.e., Oxone reagent). For samples containing both analytes, a two-step procedure can be used in which the iodide concentration is calculated from the difference in iodine levels before and after treatment of the sample with peroxymonosulfate. With this methodology, iodine and iodide levels in the 0.1-5.0 ppm range can be determined with a total workup time of approximately 60 s with a RSD of approximately 6%.

COMPONENTS IDENTIFIED IN ENERGY-RELATED WASTES AND EFFLUENTS

EPA Science Inventory

A state-of-the-art review of the characterization of solid wastes and aqueous effluents generated by energy-related processes was conducted. The reliability of these data was evaluated according to preselected criteria or sample source, sampling and analytical methodology, and da...

SOURCE SAMPLING AND ANALYSIS GUIDANCE - A METHODS DIRECTORY

EPA Science Inventory

Sampling and analytical methodologies are needed by EPA and industry for testing stationary sources for specific organic compounds such as those listed under the Resource Conservation and Recovery Act (RCRA) Appendix VIII and Appendix IX and the Clean Air Act of 1990. omputerized...

Microextraction by packed sorbent: an emerging, selective and high-throughput extraction technique in bioanalysis.

PubMed

Pereira, Jorge; Câmara, José S; Colmsjö, Anders; Abdel-Rehim, Mohamed

2014-06-01

Sample preparation is an important analytical step regarding the isolation and concentration of desired components from complex matrices and greatly influences their reliable and accurate analysis and data quality. It is the most labor-intensive and error-prone process in analytical methodology and, therefore, may influence the analytical performance of the target analytes quantification. Many conventional sample preparation methods are relatively complicated, involving time-consuming procedures and requiring large volumes of organic solvents. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low volume or no solvent consumption. Micro-extraction techniques, such as micro-extraction by packed sorbent (MEPS), have these advantages over the traditional techniques. This paper gives an overview of MEPS technique, including the role of sample preparation in bioanalysis, the MEPS description namely MEPS formats (on- and off-line), sorbents, experimental and protocols, factors that affect the MEPS performance, and the major advantages and limitations of MEPS compared with other sample preparation techniques. We also summarize MEPS recent applications in bioanalysis. Copyright © 2014 John Wiley & Sons, Ltd.

Analytical methodologies for aluminium speciation in environmental and biological samples--a review.

PubMed

Bi, S P; Yang, X D; Zhang, F P; Wang, X L; Zou, G W

2001-08-01

It is recognized that aluminium (Al) is a potential environmental hazard. Acidic deposition has been linked to increased Al concentrations in natural waters. Elevated levels of Al might have serious consequences for biological communities. Of particular interest is the speciation of Al in aquatic environments, because Al toxicity depends on its forms and concentrations. In this paper, advances in analytical methodologies for Al speciation in environmental and biological samples during the past five years are reviewed. Concerns about the specific problems of Al speciation and highlights of some important methods are elucidated in sections devoted to hybrid techniques (HPLC or FPLC coupled with ET-AAS, ICP-AES, or ICP-MS), flow-injection analysis (FIA), nuclear magnetic resonance (27Al NMR), electrochemical analysis, and computer simulation. More than 130 references are cited.

Determination of trace levels of parabens in real matrices by bar adsorptive microextraction using selective sorbent phases.

PubMed

Almeida, C; Nogueira, J M F

2014-06-27

In the present work, the development of an analytical methodology which combines bar adsorptive microextraction with microliquid desorption followed by high performance liquid chromatography-diode array detection (BAμE-μLD/HPLC-DAD) is proposed for the determination of trace levels of four parabens (methyl, ethyl, propyl and buthyl paraben) in real matrices. By comparing six polymer (P1, P2, P3, P4, P5 and P6) and five activated carbon (AC1, AC2, AC3, AC4 and AC5) coatings through BAμE, AC2 exhibited much higher selectivity and efficiency from all the sorbent phases tested, even when compared with the commercial stir bar sorptive extraction with polydimethylsiloxane. Assays performed through BAμE(AC2, 1.7mg) on 25mL of ultrapure water samples spiked at the 8.0μg/L level, yielded recoveries ranging from 85.6±6.3% to 100.6±11.8%, under optimized experimental conditions. The analytical performance showed also convenient limits of detection (0.1μg/L) and quantification (0.3μg/L), as well as good linear dynamic ranges (0.5-28.0μg/L) with remarkable determination coefficients (r(2)>0.9982). Excellent repeatability was also achieved through intraday (RSD<10.2%) and interday (RSD<10.0%) assays. By downsizing the analytical device to half-length (BAμE(AC2, 0.9mg)), similar analytical data was also achieved for the four parabens, under optimized experimental conditions, showing that this analytical technology can be design to operate with lower volumes of sample and desorption solvent, thus increasing the sensitivity and effectiveness. The application of the proposed analytical approach using the standard addition methodology on tap, underground, estuarine, swimming pool and waste water samples, as well as on commercial cosmetic products and urine samples, revealed good sensitivity, absence of matrix effects and the occurrence of levels of some parabens. Moreover, the present methodology is easy to implement, reliable, sensitive, requiring low sample and minimized desorption solvent volume, having the possibility to tune the most selective sorbent coating, according to the target compounds involved. Copyright © 2014 Elsevier B.V. All rights reserved.

The analytical calibration in (bio)imaging/mapping of the metallic elements in biological samples--definitions, nomenclature and strategies: state of the art.

PubMed

Jurowski, Kamil; Buszewski, Bogusław; Piekoszewski, Wojciech

2015-01-01

Nowadays, studies related to the distribution of metallic elements in biological samples are one of the most important issues. There are many articles dedicated to specific analytical atomic spectrometry techniques used for mapping/(bio)imaging the metallic elements in various kinds of biological samples. However, in such literature, there is a lack of articles dedicated to reviewing calibration strategies, and their problems, nomenclature, definitions, ways and methods used to obtain quantitative distribution maps. The aim of this article was to characterize the analytical calibration in the (bio)imaging/mapping of the metallic elements in biological samples including (1) nomenclature; (2) definitions, and (3) selected and sophisticated, examples of calibration strategies with analytical calibration procedures applied in the different analytical methods currently used to study an element's distribution in biological samples/materials such as LA ICP-MS, SIMS, EDS, XRF and others. The main emphasis was placed on the procedures and methodology of the analytical calibration strategy. Additionally, the aim of this work is to systematize the nomenclature for the calibration terms: analytical calibration, analytical calibration method, analytical calibration procedure and analytical calibration strategy. The authors also want to popularize the division of calibration methods that are different than those hitherto used. This article is the first work in literature that refers to and emphasizes many different and complex aspects of analytical calibration problems in studies related to (bio)imaging/mapping metallic elements in different kinds of biological samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Toward decentralized analysis of mercury (II) in real samples. A critical review on nanotechnology-based methodologies.

PubMed

Botasini, Santiago; Heijo, Gonzalo; Méndez, Eduardo

2013-10-24

In recent years, it has increased the number of works focused on the development of novel nanoparticle-based sensors for mercury detection, mainly motivated by the need of low cost portable devices capable of giving fast and reliable analytical response, thus contributing to the analytical decentralization. Methodologies employing colorimetric, fluorometric, magnetic, and electrochemical output signals allowed reaching detection limits within the pM and nM ranges. Most of these developments proved their suitability in detecting and quantifying mercury (II) ions in synthetic solutions or spiked water samples. However, the state of art in these technologies is still behind the standard methods of mercury quantification, such as cold vapor atomic absorption spectrometry and inductively coupled plasma techniques, in terms of reliability and sensitivity. This is mainly because the response of nanoparticle-based sensors is highly affected by the sample matrix. The developed analytical nanosystems may fail in real samples because of the negative incidence of the ionic strength and the presence of exchangeable ligands. The aim of this review is to critically consider the recently published innovations in this area, and highlight the needs to include more realistic assays in future research in order to make these advances suitable for on-site analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

Direct trace-elemental analysis of urine samples by laser ablation-inductively coupled plasma mass spectrometry after sample deposition on clinical filter papers.

PubMed

Aramendía, Maite; Rello, Luis; Vanhaecke, Frank; Resano, Martín

2012-10-16

Collection of biological fluids on clinical filter papers shows important advantages from a logistic point of view, although analysis of these specimens is far from straightforward. Concerning urine analysis, and particularly when direct trace elemental analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) is aimed at, several problems arise, such as lack of sensitivity or different distribution of the analytes on the filter paper, rendering obtaining reliable quantitative results quite difficult. In this paper, a novel approach for urine collection is proposed, which circumvents many of these problems. This methodology consists on the use of precut filter paper discs where large amounts of sample can be retained upon a single deposition. This provides higher amounts of the target analytes and, thus, sufficient sensitivity, and allows addition of an adequate internal standard at the clinical lab prior to analysis, therefore making it suitable for a strategy based on unsupervised sample collection and ulterior analysis at referral centers. On the basis of this sampling methodology, an analytical method was developed for the direct determination of several elements in urine (Be, Bi, Cd, Co, Cu, Ni, Sb, Sn, Tl, Pb, and V) at the low μg L(-1) level by means of LA-ICPMS. The method developed provides good results in terms of accuracy and LODs (≤1 μg L(-1) for most of the analytes tested), with a precision in the range of 15%, fit-for-purpose for clinical control analysis.

Determination of tocopherols and sitosterols in seeds and nuts by QuEChERS-liquid chromatography.

PubMed

Delgado-Zamarreño, M Milagros; Fernández-Prieto, Cristina; Bustamante-Rangel, Myriam; Pérez-Martín, Lara

2016-02-01

In the present work a simple, reliable and affordable sample treatment method for the simultaneous analysis of tocopherols and free phytosterols in nuts was developed. Analyte extraction was carried out using the QuEChERS methodology and analyte separation and detection were accomplished using HPLC-DAD. The use of this methodology for the extraction of natural occurring substances provides advantages such as speed, simplicity and ease of use. The parameters evaluated for the validation of the method developed included the linearity of the calibration plots, the detection and quantification limits, repeatability, reproducibility and recovery. The proposed method was successfully applied to the analysis of tocopherols and free phytosterols in samples of almonds, cashew nuts, hazelnuts, peanuts, tiger nuts, sun flower seeds and pistachios. Copyright © 2015 Elsevier Ltd. All rights reserved.

Newcomer adjustment during organizational socialization: a meta-analytic review of antecedents, outcomes, and methods.

PubMed

Bauer, Talya N; Bodner, Todd; Erdogan, Berrin; Truxillo, Donald M; Tucker, Jennifer S

2007-05-01

The authors tested a model of antecedents and outcomes of newcomer adjustment using 70 unique samples of newcomers with meta-analytic and path modeling techniques. Specifically, they proposed and tested a model in which adjustment (role clarity, self-efficacy, and social acceptance) mediated the effects of organizational socialization tactics and information seeking on socialization outcomes (job satisfaction, organizational commitment, job performance, intentions to remain, and turnover). The results generally supported this model. In addition, the authors examined the moderating effects of methodology on these relationships by coding for 3 methodological issues: data collection type (longitudinal vs. cross-sectional), sample characteristics (school-to-work vs. work-to-work transitions), and measurement of the antecedents (facet vs. composite measurement). Discussion focuses on the implications of the findings and suggestions for future research. 2007 APA, all rights reserved

Single-Case Experimental Designs: A Systematic Review of Published Research and Current Standards

PubMed Central

Smith, Justin D.

2013-01-01

This article systematically reviews the research design and methodological characteristics of single-case experimental design (SCED) research published in peer-reviewed journals between 2000 and 2010. SCEDs provide researchers with a flexible and viable alternative to group designs with large sample sizes. However, methodological challenges have precluded widespread implementation and acceptance of the SCED as a viable complementary methodology to the predominant group design. This article includes a description of the research design, measurement, and analysis domains distinctive to the SCED; a discussion of the results within the framework of contemporary standards and guidelines in the field; and a presentation of updated benchmarks for key characteristics (e.g., baseline sampling, method of analysis), and overall, it provides researchers and reviewers with a resource for conducting and evaluating SCED research. The results of the systematic review of 409 studies suggest that recently published SCED research is largely in accordance with contemporary criteria for experimental quality. Analytic method emerged as an area of discord. Comparison of the findings of this review with historical estimates of the use of statistical analysis indicates an upward trend, but visual analysis remains the most common analytic method and also garners the most support amongst those entities providing SCED standards. Although consensus exists along key dimensions of single-case research design and researchers appear to be practicing within these parameters, there remains a need for further evaluation of assessment and sampling techniques and data analytic methods. PMID:22845874

Multiresidue analytical method for pharmaceuticals and personal care products in sewage and sewage sludge by online direct immersion SPME on-fiber derivatization - GCMS.

PubMed

López-Serna, Rebeca; Marín-de-Jesús, David; Irusta-Mata, Rubén; García-Encina, Pedro Antonio; Lebrero, Raquel; Fdez-Polanco, María; Muñoz, Raúl

2018-08-15

The work here presented aimed at developing an analytical method for the simultaneous determination of 22 pharmaceuticals and personal care products, including 3 transformation products, in sewage and sludge. A meticulous method optimization, involving an experimental design, was carried out. The developed method was fully automated and consisted of the online extraction of 17 mL of water sample by Direct Immersion Solid Phase MicroExtraction followed by On-fiber Derivatization coupled to Gas Chromatography - Mass Spectrometry (DI-SPME - On-fiber Derivatization - GC - MS). This methodology was validated for 12 of the initial compounds as a reliable (relative recoveries above 90% for sewage and 70% for sludge; repeatability as %RSD below 10% in all cases), sensitive (LODs below 20 ng L -1 in sewage and 10 ng g -1 in sludge), versatile (sewage and sewage-sludge samples up to 15,000 ng L -1 and 900 ng g -1 , respectively) and green analytical alternative for many medium-tech routine laboratories around the world to keep up with both current and forecast environmental regulations requirements. The remaining 10 analytes initially considered showed insufficient suitability to be included in the final method. The methodology was successfully applied to real samples generated in a pilot scale sewage treatment reactor. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast methodology for the reliable determination of nonylphenol in water samples by minimal labeling isotope dilution mass spectrometry.

PubMed

Fabregat-Cabello, Neus; Castillo, Ángel; Sancho, Juan V; González, Florenci V; Roig-Navarro, Antoni Francesc

2013-08-02

In this work we have developed and validated an accurate and fast methodology for the determination of 4-nonylphenol (technical mixture) in complex matrix water samples by UHPLC-ESI-MS/MS. The procedure is based on isotope dilution mass spectrometry (IDMS) in combination with isotope pattern deconvolution (IPD), which provides the concentration of the analyte directly from the spiked sample without requiring any methodological calibration graph. To avoid any possible isotopic effect during the analytical procedure the in-house synthesized (13)C1-4-(3,6-dimethyl-3-heptyl)phenol was used as labeled compound. This proposed surrogate was able to compensate the matrix effect even from wastewater samples. A SPE pre-concentration step together with exhaustive efforts to avoid contamination were included to reach the signal-to-noise ratio necessary to detect the endogenous concentrations present in environmental samples. Calculations were performed acquiring only three transitions, achieving limits of detection lower than 100ng/g for all water matrix assayed. Recoveries within 83-108% and coefficients of variation ranging from 1.5% to 9% were obtained. On the contrary a considerable overestimation was obtained with the most usual classical calibration procedure using 4-n-nonylphenol as internal standard, demonstrating the suitability of the minimal labeling approach. Copyright © 2013 Elsevier B.V. All rights reserved.

Methodological quality of meta-analyses on treatments for chronic obstructive pulmonary disease: a cross-sectional study using the AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool.

PubMed

Ho, Robin S T; Wu, Xinyin; Yuan, Jinqiu; Liu, Siya; Lai, Xin; Wong, Samuel Y S; Chung, Vincent C H

2015-01-08

Meta-analysis (MA) of randomised trials is considered to be one of the best approaches for summarising high-quality evidence on the efficacy and safety of treatments. However, methodological flaws in MAs can reduce the validity of conclusions, subsequently impairing the quality of decision making. To assess the methodological quality of MAs on COPD treatments. A cross-sectional study on MAs of COPD trials. MAs published during 2000-2013 were sampled from the Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effect. Methodological quality was assessed using the validated AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool. Seventy-nine MAs were sampled. Only 18% considered the scientific quality of primary studies when formulating conclusions and 49% used appropriate meta-analytic methods to combine findings. The problems were particularly acute among MAs on pharmacological treatments. In 48% of MAs the authors did not report conflict of interest. Fifty-eight percent reported harmful effects of treatment. Publication bias was not assessed in 65% of MAs, and only 10% had searched non-English databases. The methodological quality of the included MAs was disappointing. Consideration of scientific quality when formulating conclusions should be made explicit. Future MAs should improve on reporting conflict of interest and harm, assessment of publication bias, prevention of language bias and use of appropriate meta-analytic methods.

Methodological quality of meta-analyses on treatments for chronic obstructive pulmonary disease: a cross-sectional study using the AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool

PubMed Central

Ho, Robin ST; Wu, Xinyin; Yuan, Jinqiu; Liu, Siya; Lai, Xin; Wong, Samuel YS; Chung, Vincent CH

2015-01-01

Background: Meta-analysis (MA) of randomised trials is considered to be one of the best approaches for summarising high-quality evidence on the efficacy and safety of treatments. However, methodological flaws in MAs can reduce the validity of conclusions, subsequently impairing the quality of decision making. Aims: To assess the methodological quality of MAs on COPD treatments. Methods: A cross-sectional study on MAs of COPD trials. MAs published during 2000–2013 were sampled from the Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effect. Methodological quality was assessed using the validated AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool. Results: Seventy-nine MAs were sampled. Only 18% considered the scientific quality of primary studies when formulating conclusions and 49% used appropriate meta-analytic methods to combine findings. The problems were particularly acute among MAs on pharmacological treatments. In 48% of MAs the authors did not report conflict of interest. Fifty-eight percent reported harmful effects of treatment. Publication bias was not assessed in 65% of MAs, and only 10% had searched non-English databases. Conclusions: The methodological quality of the included MAs was disappointing. Consideration of scientific quality when formulating conclusions should be made explicit. Future MAs should improve on reporting conflict of interest and harm, assessment of publication bias, prevention of language bias and use of appropriate meta-analytic methods. PMID:25569783

Determination of insoluble soap in agricultural soil and sewage sludge samples by liquid chromatography with ultraviolet detection.

PubMed

Cantarero, Samuel; Zafra-Gómez, Alberto; Ballesteros, Oscar; Navalón, Alberto; Vílchez, José L; Crovetto, Guillermo; Verge, Coral; de Ferrer, Juan A

2010-11-01

We have developed a new analytical procedure for determining insoluble Ca and Mg fatty acid salts (soaps) in agricultural soil and sewage sludge samples. The number of analytical methodologies that focus in the determination of insoluble soap salts in different environmental compartments is very limited. In this work, we propose a methodology that involves a sample clean-up step with petroleum ether to remove soluble salts and a conversion of Ca and Mg insoluble salts into soluble potassium salts using tripotassium ethylenediaminetetraacetate salt and potassium carbonate, followed by the extraction of analytes from the samples using microwave-assisted extraction with methanol. An improved esterification procedure using 2,4-dibromoacetophenone before the liquid chromatography with ultraviolet detection analysis also has been developed. The absence of matrix effect was demonstrated with two fatty acid Ca salts that are not commercial and are never detected in natural samples (C₁₃:₀ and C₁₇:₀). Therefore, it was possible to evaluate the matrix effect because both standards have similar environmental behavior (adsorption and precipitation) to commercial soaps (C₁₀:₀) to C₁₈:₀). We also studied the effect of the different variables on the clean-up, the conversion of Ca soap, and the extraction and derivatization procedures. The quantification limits found ranged from 0.4 to 0.8 mg/kg. The proposed method was satisfactorily applied for the development of a study on soap behavior in agricultural soil and sewage sludge samples. © 2010 SETAC.

Development of garlic bioactive compounds analytical methodology based on liquid phase microextraction using response surface design. Implications for dual analysis: Cooked and biological fluids samples.

PubMed

Ramirez, Daniela Andrea; Locatelli, Daniela Ana; Torres-Palazzolo, Carolina Andrea; Altamirano, Jorgelina Cecilia; Camargo, Alejandra Beatriz

2017-01-15

Organosulphur compounds (OSCs) present in garlic (Allium sativum L.) are responsible of several biological properties. Functional foods researches indicate the importance of quantifying these compounds in food matrices and biological fluids. For this purpose, this paper introduces a novel methodology based on dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with ultraviolet detector (HPLC-UV) for the extraction and determination of organosulphur compounds in different matrices. The target analytes were allicin, (E)- and (Z)-ajoene, 2-vinyl-4H-1,2-dithiin (2-VD), diallyl sulphide (DAS) and diallyl disulphide (DADS). The microextraction technique was optimized using an experimental design, and the analytical performance was evaluated under optimum conditions. The desirability function presented an optimal value for 600μL of chloroform as extraction solvent using acetonitrile as dispersant. The method proved to be reliable, precise and accurate. It was successfully applied to determine OSCs in cooked garlic samples as well as blood plasma and digestive fluids. Copyright © 2016 Elsevier Ltd. All rights reserved.

Computational Methodology for Absolute Calibration Curves for Microfluidic Optical Analyses

PubMed Central

Chang, Chia-Pin; Nagel, David J.; Zaghloul, Mona E.

2010-01-01

Optical fluorescence and absorption are two of the primary techniques used for analytical microfluidics. We provide a thorough yet tractable method for computing the performance of diverse optical micro-analytical systems. Sample sizes range from nano- to many micro-liters and concentrations from nano- to milli-molar. Equations are provided to trace quantitatively the flow of the fundamental entities, namely photons and electrons, and the conversion of energy from the source, through optical components, samples and spectral-selective components, to the detectors and beyond. The equations permit facile computations of calibration curves that relate the concentrations or numbers of molecules measured to the absolute signals from the system. This methodology provides the basis for both detailed understanding and improved design of microfluidic optical analytical systems. It saves prototype turn-around time, and is much simpler and faster to use than ray tracing programs. Over two thousand spreadsheet computations were performed during this study. We found that some design variations produce higher signal levels and, for constant noise levels, lower minimum detection limits. Improvements of more than a factor of 1,000 were realized. PMID:22163573

The Impact of School Bullying on Students' Academic Achievement from Teachers Point of View

ERIC Educational Resources Information Center

Al-Raqqad, Hana Khaled; Al-Bourini, Eman Saeed; Al Talahin, Fatima Mohammad; Aranki, Raghda Michael Elias

2017-01-01

The study aimed to investigate school bullying impact on students' academic achievement from teachers' perspective in Jordanian schools. The study used a descriptive analytical methodology. The research sample consisted of all schools' teachers in Amman West Area (in Jordan). The sample size consisted of 200 teachers selected from different…

Oral Reading Fluency Growth: A Sample of Methodology and Findings. Research Brief 6

ERIC Educational Resources Information Center

Tindal, Gerald; Nese, Joseph F. T.

2013-01-01

For the past 20 years, the growth of students' oral reading fluency has been investigated by a number of researchers using curriculum-based measurement. These researchers have used varied methods (student samples, measurement procedures, and analytical techniques) and yet have converged on a relatively consistent finding: General education…

Auditing of chromatographic data.

PubMed

Mabie, J T

1998-01-01

During a data audit, it is important to ensure that there is clear documentation and an audit trail. The Quality Assurance Unit should review all areas, including the laboratory, during the conduct of the sample analyses. The analytical methodology that is developed should be documented prior to sample analyses. This is an important document for the auditor, as it is the instrumental piece used by the laboratory personnel to maintain integrity throughout the process. It is expected that this document will give insight into the sample analysis, run controls, run sequencing, instrument parameters, and acceptance criteria for the samples. The sample analysis and all supporting documentation should be audited in conjunction with this written analytical method and any supporting Standard Operating Procedures to ensure the quality and integrity of the data.

Cocaine profiling for strategic intelligence, a cross-border project between France and Switzerland: part II. Validation of the statistical methodology for the profiling of cocaine.

PubMed

Lociciro, S; Esseiva, P; Hayoz, P; Dujourdy, L; Besacier, F; Margot, P

2008-05-20

Harmonisation and optimization of analytical and statistical methodologies were carried out between two forensic laboratories (Lausanne, Switzerland and Lyon, France) in order to provide drug intelligence for cross-border cocaine seizures. Part I dealt with the optimization of the analytical method and its robustness. This second part investigates statistical methodologies that will provide reliable comparison of cocaine seizures analysed on two different gas chromatographs interfaced with a flame ionisation detectors (GC-FIDs) in two distinct laboratories. Sixty-six statistical combinations (ten data pre-treatments followed by six different distance measurements and correlation coefficients) were applied. One pre-treatment (N+S: area of each peak is divided by its standard deviation calculated from the whole data set) followed by the Cosine or Pearson correlation coefficients were found to be the best statistical compromise for optimal discrimination of linked and non-linked samples. The centralisation of the analyses in one single laboratory is not a required condition anymore to compare samples seized in different countries. This allows collaboration, but also, jurisdictional control over data.

A review of selected inorganic surface water quality-monitoring practices: are we really measuring what we think, and if so, are we doing it right?

USGS Publications Warehouse

Horowitz, Arthur J.

2013-01-01

Successful environmental/water quality-monitoring programs usually require a balance between analytical capabilities, the collection and preservation of representative samples, and available financial/personnel resources. Due to current economic conditions, monitoring programs are under increasing pressure to do more with less. Hence, a review of current sampling and analytical methodologies, and some of the underlying assumptions that form the bases for these programs seems appropriate, to see if they are achieving their intended objectives within acceptable error limits and/or measurement uncertainty, in a cost-effective manner. That evaluation appears to indicate that several common sampling/processing/analytical procedures (e.g., dip (point) samples/measurements, nitrogen determinations, total recoverable analytical procedures) are generating biased or nonrepresentative data, and that some of the underlying assumptions relative to current programs, such as calendar-based sampling and stationarity are no longer defensible. The extensive use of statistical models as well as surrogates (e.g., turbidity) also needs to be re-examined because the hydrologic interrelationships that support their use tend to be dynamic rather than static. As a result, a number of monitoring programs may need redesigning, some sampling and analytical procedures may need to be updated, and model/surrogate interrelationships may require recalibration.

Electro-thermal vaporization direct analysis in real time-mass spectrometry for water contaminant analysis during space missions.

PubMed

Dwivedi, Prabha; Gazda, Daniel B; Keelor, Joel D; Limero, Thomas F; Wallace, William T; Macatangay, Ariel V; Fernández, Facundo M

2013-10-15

The development of a direct analysis in real time-mass spectrometry (DART-MS) method and first prototype vaporizer for the detection of low molecular weight (∼30-100 Da) contaminants representative of those detected in water samples from the International Space Station is reported. A temperature-programmable, electro-thermal vaporizer (ETV) was designed, constructed, and evaluated as a sampling interface for DART-MS. The ETV facilitates analysis of water samples with minimum user intervention while maximizing analytical sensitivity and sample throughput. The integrated DART-ETV-MS methodology was evaluated in both positive and negative ion modes to (1) determine experimental conditions suitable for coupling DART with ETV as a sample inlet and ionization platform for time-of-flight MS, (2) to identify analyte response ions, (3) to determine the detection limit and dynamic range for target analyte measurement, and (4) to determine the reproducibility of measurements made with the method when using manual sample introduction into the vaporizer. Nitrogen was used as the DART working gas, and the target analytes chosen for the study were ethyl acetate, acetone, acetaldehyde, ethanol, ethylene glycol, dimethylsilanediol, formaldehyde, isopropanol, methanol, methylethyl ketone, methylsulfone, propylene glycol, and trimethylsilanol.

Validation of a sampling plan to generate food composition data.

PubMed

Sammán, N C; Gimenez, M A; Bassett, N; Lobo, M O; Marcoleri, M E

2016-02-15

A methodology to develop systematic plans for food sampling was proposed. Long life whole and skimmed milk, and sunflower oil were selected to validate the methodology in Argentina. Fatty acid profile in all foods, proximal composition, and calcium's content in milk were determined with AOAC methods. The number of samples (n) was calculated applying Cochran's formula with variation coefficients ⩽12% and an estimate error (r) maximum permissible ⩽5% for calcium content in milks and unsaturated fatty acids in oil. n were 9, 11 and 21 for long life whole and skimmed milk, and sunflower oil respectively. Sample units were randomly collected from production sites and sent to labs. Calculated r with experimental data was ⩽10%, indicating high accuracy in the determination of analyte content of greater variability and reliability of the proposed sampling plan. The methodology is an adequate and useful tool to develop sampling plans for food composition analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improvements in the analytical methodology for the residue determination of the herbicide glyphosate in soils by liquid chromatography coupled to mass spectrometry.

PubMed

Botero-Coy, A M; Ibáñez, M; Sancho, J V; Hernández, F

2013-05-31

The determination of glyphosate (GLY) in soils is of great interest due to the widespread use of this herbicide and the need of assessing its impact on the soil/water environment. However, its residue determination is very problematic especially in soils with high organic matter content, where strong interferences are normally observed, and because of the particular physico-chemical characteristics of this polar/ionic herbicide. In the present work, we have improved previous LC-MS/MS analytical methodology reported for GLY and its main metabolite AMPA in order to be applied to "difficult" soils, like those commonly found in South-America, where this herbicide is extensively used in large areas devoted to soya or maize, among other crops. The method is based on derivatization with FMOC followed by LC-MS/MS analysis, using triple quadrupole. After extraction with potassium hydroxide, a combination of extract dilution, adjustment to appropriate pH, and solid phase extraction (SPE) clean-up was applied to minimize the strong interferences observed. Despite the clean-up performed, the use of isotope labelled glyphosate as internal standard (ILIS) was necessary for the correction of matrix effects and to compensate for any error occurring during sample processing. The analytical methodology was satisfactorily validated in four soils from Colombia and Argentina fortified at 0.5 and 5mg/kg. In contrast to most LC-MS/MS methods, where the acquisition of two transitions is recommended, monitoring all available transitions was required for confirmation of positive samples, as some of them were interfered by unknown soil components. This was observed not only for GLY and AMPA but also for the ILIS. Analysis by QTOF MS was useful to confirm the presence of interferent compounds that shared the same nominal mass of analytes as well as some of their main product ions. Therefore, the selection of specific transitions was crucial to avoid interferences. The methodology developed was applied to the analysis of 26 soils from different areas of Colombia and Argentina, and the method robustness was demonstrated by analysis of quality control samples along 4 months. Copyright © 2012 Elsevier B.V. All rights reserved.

Reference Intervals of Common Clinical Chemistry Analytes for Adults in Hong Kong.

PubMed

Lo, Y C; Armbruster, David A

2012-04-01

Defining reference intervals is a major challenge because of the difficulty in recruiting volunteers to participate and testing samples from a significant number of healthy reference individuals. Historical literature citation intervals are often suboptimal because they're be based on obsolete methods and/or only a small number of poorly defined reference samples. Blood donors in Hong Kong gave permission for additional blood to be collected for reference interval testing. The samples were tested for twenty-five routine analytes on the Abbott ARCHITECT clinical chemistry system. Results were analyzed using the Rhoads EP evaluator software program, which is based on the CLSI/IFCC C28-A guideline, and defines the reference interval as the 95% central range. Method specific reference intervals were established for twenty-five common clinical chemistry analytes for a Chinese ethnic population. The intervals were defined for each gender separately and for genders combined. Gender specific or combined gender intervals were adapted as appropriate for each analyte. A large number of healthy, apparently normal blood donors from a local ethnic population were tested to provide current reference intervals for a new clinical chemistry system. Intervals were determined following an accepted international guideline. Laboratories using the same or similar methodologies may adapt these intervals if deemed validated and deemed suitable for their patient population. Laboratories using different methodologies may be able to successfully adapt the intervals for their facilities using the reference interval transference technique based on a method comparison study.

NONCARCINOGENIC EFFECTS OF CHROMIUM: UPDATE TO HEALTH ASSESSMENT DOCUMENT

EPA Science Inventory

This 1990 document updates the 1984 Health Assessment Document for Chromium by addressing issues regarding noncarcinogenic health effects of chromium: oxidation states and persistence of these states in the environment, sampling and analytical methodology to differentiate these o...

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR LABORATORY ANALYSIS OF HAIR SAMPLES FOR MERCURY (RTI-L-1.0)

EPA Science Inventory

The purpose of this protocol is to provide guidelines for the analysis of hair samples for total mercury by cold vapor atomic fluorescence (CVAFS) spectrometry. This protocol describes the methodology and all other analytical aspects involved in the analysis. Keywords: hair; s...

Immediate drop on demand technology (I-DOT) coupled with mass spectrometry via an open port sampling interface.

PubMed

Van Berkel, Gary J; Kertesz, Vilmos; Boeltz, Harry

2017-11-01

The aim of this work was to demonstrate and evaluate the analytical performance of coupling the immediate drop on demand technology to a mass spectrometer via the recently introduced open port sampling interface and ESI. Methodology & results: A maximum sample analysis throughput of 5 s per sample was demonstrated. Signal reproducibility was 10% or better as demonstrated by the quantitative analysis of propranolol and its stable isotope-labeled internal standard propranolol-d7. The ability of the system to multiply charge and analyze macromolecules was demonstrated using the protein cytochrome c. This immediate drop on demand technology/open port sampling interface/ESI-MS combination allowed for the quantitative analysis of relatively small mass analytes and was used for the identification of macromolecules like proteins.

Insights from two industrial hygiene pilot e-cigarette passive vaping studies.

PubMed

Maloney, John C; Thompson, Michael K; Oldham, Michael J; Stiff, Charles L; Lilly, Patrick D; Patskan, George J; Shafer, Kenneth H; Sarkar, Mohamadi A

2016-01-01

While several reports have been published using research methods of estimating exposure risk to e-cigarette vapors in nonusers, only two have directly measured indoor air concentrations from vaping using validated industrial hygiene sampling methodology. Our first study was designed to measure indoor air concentrations of nicotine, menthol, propylene glycol, glycerol, and total particulates during the use of multiple e-cigarettes in a well-characterized room over a period of time. Our second study was a repeat of the first study, and it also evaluated levels of formaldehyde. Measurements were collected using active sampling, near real-time and direct measurement techniques. Air sampling incorporated industrial hygiene sampling methodology using analytical methods established by the National Institute of Occupational Safety and Health and the Occupational Safety and Health Administration. Active samples were collected over a 12-hr period, for 4 days. Background measurements were taken in the same room the day before and the day after vaping. Panelists (n = 185 Study 1; n = 145 Study 2) used menthol and non-menthol MarkTen prototype e-cigarettes. Vaping sessions (six, 1-hr) included 3 prototypes, with total number of puffs ranging from 36-216 per session. Results of the active samples were below the limit of quantitation of the analytical methods. Near real-time data were below the lowest concentration on the established calibration curves. Data from this study indicate that the majority of chemical constituents sampled were below quantifiable levels. Formaldehyde was detected at consistent levels during all sampling periods. These two studies found that indoor vaping of MarkTen prototype e-cigarette does not produce chemical constituents at quantifiable levels or background levels using standard industrial hygiene collection techniques and analytical methods.

Determination of As, Se, and Hg in fuel samples by in-chamber chemical vapor generation ICP OES using a Flow Blurring® multinebulizer.

PubMed

García, Miriam; Aguirre, Miguel Ángel; Canals, Antonio

2017-09-01

In this work, a new and simple analytical methodology based on in-chamber chemical vapor generation has been developed for the spectrochemical analysis of commercial fuel samples. A multiple nebulizer with three nebulization units has been employed for this purpose: One unit was used for sample introduction, while the other two were used for the necessary reagent introduction. In this way, the aerosols were mixed inside the spray chamber. Through this method, analyte transport and, therefore, sensitivity are improved in inductively coupled plasma-optical emission spectrometry. The factors (i.e., variables), influencing chemical vapor generation, have been optimized using a multivariate approach. Under optimum chemical vapor generation conditions ([NaBH 4 ] = 1.39%, [HCl] = 2.97 M, total liquid flow = 936 μL min -1 ), the proposed sample introduction system allowed the determination of arsenic, selenium, and mercury up to 5 μg g -1 with a limit of detection of 25, 140, and 13 μg kg -1 , respectively. Analyzing spiked commercial fuel samples, recovery values obtained were between 96 and 113%, and expanded uncertainty values ranged from 4 to 16%. The most striking practical conclusion of this investigation is that no carbon deposit appears on the plasma torch after extended periods of working. Graphical abstract A new and simple analytical methodology based on in-chamber chemical vapor generation has been developed for the spectrochemical analysis of commercial fuel samples in ICP OES.

Challenges and perspectives in quantitative NMR.

PubMed

Giraudeau, Patrick

2017-01-01

This perspective article summarizes, from the author's point of view at the beginning of 2016, the major challenges and perspectives in the field of quantitative NMR. The key concepts in quantitative NMR are first summarized; then, the most recent evolutions in terms of resolution and sensitivity are discussed, as well as some potential future research directions in this field. A particular focus is made on methodologies capable of boosting the resolution and sensitivity of quantitative NMR, which could open application perspectives in fields where the sample complexity and the analyte concentrations are particularly challenging. These include multi-dimensional quantitative NMR and hyperpolarization techniques such as para-hydrogen-induced polarization or dynamic nuclear polarization. Because quantitative NMR cannot be dissociated from the key concepts of analytical chemistry, i.e. trueness and precision, the methodological developments are systematically described together with their level of analytical performance. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Comparison of soil sampling and analytical methods for asbestos at the Sumas Mountain Asbestos Site-Working towards a toolbox for better assessment.

PubMed

Wroble, Julie; Frederick, Timothy; Frame, Alicia; Vallero, Daniel

2017-01-01

Established soil sampling methods for asbestos are inadequate to support risk assessment and risk-based decision making at Superfund sites due to difficulties in detecting asbestos at low concentrations and difficulty in extrapolating soil concentrations to air concentrations. Environmental Protection Agency (EPA)'s Office of Land and Emergency Management (OLEM) currently recommends the rigorous process of Activity Based Sampling (ABS) to characterize site exposures. The purpose of this study was to compare three soil analytical methods and two soil sampling methods to determine whether one method, or combination of methods, would yield more reliable soil asbestos data than other methods. Samples were collected using both traditional discrete ("grab") samples and incremental sampling methodology (ISM). Analyses were conducted using polarized light microscopy (PLM), transmission electron microscopy (TEM) methods or a combination of these two methods. Data show that the fluidized bed asbestos segregator (FBAS) followed by TEM analysis could detect asbestos at locations that were not detected using other analytical methods; however, this method exhibited high relative standard deviations, indicating the results may be more variable than other soil asbestos methods. The comparison of samples collected using ISM versus discrete techniques for asbestos resulted in no clear conclusions regarding preferred sampling method. However, analytical results for metals clearly showed that measured concentrations in ISM samples were less variable than discrete samples.

Comparison of soil sampling and analytical methods for asbestos at the Sumas Mountain Asbestos Site—Working towards a toolbox for better assessment

PubMed Central

2017-01-01

Established soil sampling methods for asbestos are inadequate to support risk assessment and risk-based decision making at Superfund sites due to difficulties in detecting asbestos at low concentrations and difficulty in extrapolating soil concentrations to air concentrations. Environmental Protection Agency (EPA)’s Office of Land and Emergency Management (OLEM) currently recommends the rigorous process of Activity Based Sampling (ABS) to characterize site exposures. The purpose of this study was to compare three soil analytical methods and two soil sampling methods to determine whether one method, or combination of methods, would yield more reliable soil asbestos data than other methods. Samples were collected using both traditional discrete (“grab”) samples and incremental sampling methodology (ISM). Analyses were conducted using polarized light microscopy (PLM), transmission electron microscopy (TEM) methods or a combination of these two methods. Data show that the fluidized bed asbestos segregator (FBAS) followed by TEM analysis could detect asbestos at locations that were not detected using other analytical methods; however, this method exhibited high relative standard deviations, indicating the results may be more variable than other soil asbestos methods. The comparison of samples collected using ISM versus discrete techniques for asbestos resulted in no clear conclusions regarding preferred sampling method. However, analytical results for metals clearly showed that measured concentrations in ISM samples were less variable than discrete samples. PMID:28759607

Coalescence computations for large samples drawn from populations of time-varying sizes

PubMed Central

Polanski, Andrzej; Szczesna, Agnieszka; Garbulowski, Mateusz; Kimmel, Marek

2017-01-01

We present new results concerning probability distributions of times in the coalescence tree and expected allele frequencies for coalescent with large sample size. The obtained results are based on computational methodologies, which involve combining coalescence time scale changes with techniques of integral transformations and using analytical formulae for infinite products. We show applications of the proposed methodologies for computing probability distributions of times in the coalescence tree and their limits, for evaluation of accuracy of approximate expressions for times in the coalescence tree and expected allele frequencies, and for analysis of large human mitochondrial DNA dataset. PMID:28170404

Analysis of street sweepings, Portland, Oregon

USGS Publications Warehouse

Miller, Timothy L.; Rinella, Joseph F.; McKenzie, Stuart W.; Parmenter, Jerry

1977-01-01

A brief study involving collection and analysis of street sweepings was undertaken to provide the U.S. Army Corps of Engineers with data on physical, chemical, and biological characteristics of dust and dirt accumulating on Portland streets. Most of the analyses selected were based on the pollutant loads predicted by the Storage, Treatment, Overflow, and Runoff Model (STORM). Five different basins were selected for sampling, and samples were collected three times in each basin. Because the literature reports no methodology for analysis of dust and dirt, the analytical methodology is described in detail. Results of the analyses are summarized in table 1.

Clinical Chemistry Laboratory Automation in the 21st Century - Amat Victoria curam (Victory loves careful preparation)

PubMed Central

Armbruster, David A; Overcash, David R; Reyes, Jaime

2014-01-01

The era of automation arrived with the introduction of the AutoAnalyzer using continuous flow analysis and the Robot Chemist that automated the traditional manual analytical steps. Successive generations of stand-alone analysers increased analytical speed, offered the ability to test high volumes of patient specimens, and provided large assay menus. A dichotomy developed, with a group of analysers devoted to performing routine clinical chemistry tests and another group dedicated to performing immunoassays using a variety of methodologies. Development of integrated systems greatly improved the analytical phase of clinical laboratory testing and further automation was developed for pre-analytical procedures, such as sample identification, sorting, and centrifugation, and post-analytical procedures, such as specimen storage and archiving. All phases of testing were ultimately combined in total laboratory automation (TLA) through which all modules involved are physically linked by some kind of track system, moving samples through the process from beginning-to-end. A newer and very powerful, analytical methodology is liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). LC-MS/MS has been automated but a future automation challenge will be to incorporate LC-MS/MS into TLA configurations. Another important facet of automation is informatics, including middleware, which interfaces the analyser software to a laboratory information systems (LIS) and/or hospital information systems (HIS). This software includes control of the overall operation of a TLA configuration and combines analytical results with patient demographic information to provide additional clinically useful information. This review describes automation relevant to clinical chemistry, but it must be recognised that automation applies to other specialties in the laboratory, e.g. haematology, urinalysis, microbiology. It is a given that automation will continue to evolve in the clinical laboratory, limited only by the imagination and ingenuity of laboratory scientists. PMID:25336760

Clinical Chemistry Laboratory Automation in the 21st Century - Amat Victoria curam (Victory loves careful preparation).

PubMed

Armbruster, David A; Overcash, David R; Reyes, Jaime

2014-08-01

The era of automation arrived with the introduction of the AutoAnalyzer using continuous flow analysis and the Robot Chemist that automated the traditional manual analytical steps. Successive generations of stand-alone analysers increased analytical speed, offered the ability to test high volumes of patient specimens, and provided large assay menus. A dichotomy developed, with a group of analysers devoted to performing routine clinical chemistry tests and another group dedicated to performing immunoassays using a variety of methodologies. Development of integrated systems greatly improved the analytical phase of clinical laboratory testing and further automation was developed for pre-analytical procedures, such as sample identification, sorting, and centrifugation, and post-analytical procedures, such as specimen storage and archiving. All phases of testing were ultimately combined in total laboratory automation (TLA) through which all modules involved are physically linked by some kind of track system, moving samples through the process from beginning-to-end. A newer and very powerful, analytical methodology is liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). LC-MS/MS has been automated but a future automation challenge will be to incorporate LC-MS/MS into TLA configurations. Another important facet of automation is informatics, including middleware, which interfaces the analyser software to a laboratory information systems (LIS) and/or hospital information systems (HIS). This software includes control of the overall operation of a TLA configuration and combines analytical results with patient demographic information to provide additional clinically useful information. This review describes automation relevant to clinical chemistry, but it must be recognised that automation applies to other specialties in the laboratory, e.g. haematology, urinalysis, microbiology. It is a given that automation will continue to evolve in the clinical laboratory, limited only by the imagination and ingenuity of laboratory scientists.

Analytical procedures for the determination of fuel combustion products, anti-corrosive compounds, and de-icing compounds in airport runoff water samples.

PubMed

Sulej, Anna Maria; Polkowska, Żaneta; Astel, Aleksander; Namieśnik, Jacek

2013-12-15

The purpose of this study is to propose and evaluate new procedures for determination of fuel combustion products, anti-corrosive and de-icing compounds in runoff water samples collected from the airports located in different regions and characterized by different levels of the activity expressed by the number of flights and the number of passengers (per year). The most difficult step in the analytical procedure used for the determination of PAHs, benzotriazoles and glycols is sample preparation stage, due to diverse matrix composition, the possibility of interference associated with the presence of components with similar physicochemical properties. In this study, five different versions of sample preparation using extraction techniques, such as: LLE and SPE, were tested. In all examined runoff water samples collected from the airports, the presence of PAH compounds and glycols was observed. In majority of the samples, BT compounds were determined. Runoff water samples collected from the areas of Polish and British international airports as well as local airports had similar qualitative composition, but quantitative composition of the analytes was very diverse. New and validated analytical methodologies ensure that the necessary information for assessing the negative impact of airport activities on the environment can be obtained. © 2013 Elsevier B.V. All rights reserved.

Determination of Carbonyl Compounds in Cork Agglomerates by GDME-HPLC-UV: Identification of the Extracted Compounds by HPLC-MS/MS.

PubMed

Brandão, Pedro Francisco; Ramos, Rui Miguel; Almeida, Paulo Joaquim; Rodrigues, José António

2017-02-08

A new approach is proposed for the extraction and determination of carbonyl compounds in solid samples, such as wood or cork materials. Cork products are used as building materials due to their singular characteristics; however, little is known about its aldehyde emission potential and content. Sample preparation was done by using a gas-diffusion microextraction (GDME) device for the direct extraction of volatile aldehydes and derivatization with 2,4-dinitrophenylhydrazine. Analytical determination of the extracts was done by HPLC-UV, with detection at 360 nm. The developed methodology proved to be a reliable tool for aldehyde determination in cork agglomerate samples with suitable method features. Mass spectrometry studies were performed for each sample, which enabled the identification, in the extracts, of the derivatization products of a total of 13 aldehydes (formaldehyde, acetaldehyde, furfural, propanal, 5-methylfurfural, butanal, benzaldehyde, pentanal, hexanal, trans-2-heptenal, heptanal, octanal, and trans-2-nonenal) and 4 ketones (3-hydroxy-2-butanone, acetone, cyclohexanone, and acetophenone). This new analytical methodology simultaneously proved to be consistent for the identification and determination of aldehydes in cork agglomerates and a very simple and straightforward procedure.

Ultra-high-performance liquid chromatography-Time-of-flight high resolution mass spectrometry to quantify acidic drugs in wastewater.

PubMed

Becerra-Herrera, Mercedes; Honda, Luis; Richter, Pablo

2015-12-04

A novel analytical approach involving an improved rotating-disk sorptive extraction (RDSE) procedure and ultra-high-performance liquid chromatography (UHPLC) coupled to an ultraspray electrospray ionization source (UESI) and time-of-flight mass spectrometry (TOF/MS), in trap mode, was developed to identify and quantify four non-steroidal anti-inflammatory drugs (NSAIDs) (naproxen, ibuprofen, ketoprofen and diclofenac) and two anti-cholesterol drugs (ACDs) (clofibric acid and gemfibrozil) that are widely used and typically found in water samples. The method reduced the amount of both sample and reagents used and also the time required for the whole analysis, resulting in a reliable and green analytical strategy. The analytical eco-scale was calculated, showing that this methodology is an excellent green analysis, increasing its ecological worth. The detection limits (LOD) and precision (%RSD) were lower than 90ng/L and 10%, respectively. Matrix effects and recoveries were studied using samples from the influent of a wastewater treatment plant (WWTP). All the compounds exhibited suppression of their signals due to matrix effects, and the recoveries were approximately 100%. The applicability and reliability of this methodology were confirmed through the analysis of influent and effluent samples from a WWTP in Santiago, Chile, obtaining concentrations ranging from 1.1 to 20.5μg/L and from 0.5 to 8.6μg/L, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Analytical methodologies based on LC-MS/MS for monitoring selected emerging compounds in liquid and solid phases of the sewage sludge.

PubMed

Boix, C; Ibáñez, M; Fabregat-Safont, D; Morales, E; Pastor, L; Sancho, J V; Sánchez-Ramírez, J E; Hernández, F

2016-01-01

In this work, two analytical methodologies based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) were developed for quantification of emerging pollutants identified in sewage sludge after a previous wide-scope screening. The target list included 13 emerging contaminants (EC): thiabendazole, acesulfame, fenofibric acid, valsartan, irbesartan, salicylic acid, diclofenac, carbamazepine, 4-aminoantipyrine (4-AA), 4-acetyl aminoantipyrine (4-AAA), 4-formyl aminoantipyrine (4-FAA), venlafaxine and benzoylecgonine. The aqueous and solid phases of the sewage sludge were analyzed making use of Solid-Phase Extraction (SPE) and UltraSonic Extraction (USE) for sample treatment, respectively. The methods were validated at three concentration levels: 0.2, 2 and 20 μg L(-1) for the aqueous phase, and 50, 500 and 2000 μg kg(-1) for the solid phase of the sludge. In general, the method was satisfactorily validated, showing good recoveries (70-120%) and precision (RSD < 20%). Regarding the limit of quantification (LOQ), it was below 0.1 μg L(-1) in the aqueous phase and below 50 μg kg(-1) in the solid phase for the majority of the analytes. The method applicability was tested by analysis of samples from a wider study on degradation of emerging pollutants in sewage sludge under anaerobic digestion. The key benefits of these methodologies are: • SPE and USE are appropriate sample procedures to extract selected emerging contaminants from the aqueous phase of the sewage sludge and the solid residue. • LC-MS/MS is highly suitable for determining emerging contaminants in both sludge phases. • Up to our knowledge, the main metabolites of dipyrone had not been studied before in sewage sludge.

Design and development of molecularly imprinted polymers for the selective extraction of deltamethrin in olive oil: An integrated computational-assisted approach.

PubMed

Martins, Nuno; Carreiro, Elisabete P; Locati, Abel; Ramalho, João P Prates; Cabrita, Maria João; Burke, Anthony J; Garcia, Raquel

2015-08-28

This work firstly addresses the design and development of molecularly imprinted systems selective for deltamethrin aiming to provide a suitable sorbent for solid phase (SPE) extraction that will be further used for the implementation of an analytical methodology for the trace analysis of the target pesticide in spiked olive oil samples. To achieve this goal, a preliminary evaluation of the molecular recognition and selectivity of the molecularly imprinted polymers has been performed. In order to investigate the complexity of the mechanistic basis for template selective recognition in these polymeric matrices, the use of a quantum chemical approach has been attempted providing new insights about the mechanisms underlying template recognition, and in particular the crucial role of the crosslinker agent and the solvent used. Thus, DFT calculations corroborate the results obtained by experimental molecular recognition assays enabling one to select the most suitable imprinting system for MISPE extraction technique which encompasses acrylamide as functional monomer and ethylene glycol dimethacrylate as crosslinker. Furthermore, an analytical methodology comprising a sample preparation step based on solid phase extraction has been implemented using this "tailor made" imprinting system as sorbent, for the selective isolation/pre-concentration of deltamethrin from olive oil samples. Molecularly imprinted solid phase extraction (MISPE) methodology was successfully applied for the clean-up of spiked olive oil samples, with recovery rates up to 94%. Copyright © 2015 Elsevier B.V. All rights reserved.

A sustainable on-line CapLC method for quantifying antifouling agents like irgarol-1051 and diuron in water samples: Estimation of the carbon footprint.

PubMed

Pla-Tolós, J; Serra-Mora, P; Hakobyan, L; Molins-Legua, C; Moliner-Martinez, Y; Campins-Falcó, P

2016-11-01

In this work, in-tube solid phase microextraction (in-tube SPME) coupled to capillary LC (CapLC) with diode array detection has been reported, for on-line extraction and enrichment of booster biocides (irgarol-1051 and diuron) included in Water Frame Directive 2013/39/UE (WFD). The analytical performance has been successfully demonstrated. Furthermore, in the present work, the environmental friendliness of the procedure has been quantified by means of the implementation of the carbon footprint calculation of the analytical procedure and the comparison with other methodologies previously reported. Under the optimum conditions, the method presents good linearity over the range assayed, 0.05-10μg/L for irgarol-1051 and 0.7-10μg/L for diuron. The LODs were 0.015μg/L and 0.2μg/L for irgarol-1051 and diuron, respectively. Precision was also satisfactory (relative standard deviation, RSD<3.5%). The proposed methodology was applied to monitor water samples, taking into account the EQS standards for these compounds. The carbon footprint values for the proposed procedure consolidate the operational efficiency (analytical and environmental performance) of in-tube SPME-CapLC-DAD, in general, and in particular for determining irgarol-1051 and diuron in water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluorescence Spectroscopy for the Monitoring of Food Processes.

PubMed

Ahmad, Muhammad Haseeb; Sahar, Amna; Hitzmann, Bernd

Different analytical techniques have been used to examine the complexity of food samples. Among them, fluorescence spectroscopy cannot be ignored in developing rapid and non-invasive analytical methodologies. It is one of the most sensitive spectroscopic approaches employed in identification, classification, authentication, quantification, and optimization of different parameters during food handling, processing, and storage and uses different chemometric tools. Chemometrics helps to retrieve useful information from spectral data utilized in the characterization of food samples. This contribution discusses in detail the potential of fluorescence spectroscopy of different foods, such as dairy, meat, fish, eggs, edible oil, cereals, fruit, vegetables, etc., for qualitative and quantitative analysis with different chemometric approaches.

Supercritical fluid extraction and ultra performance liquid chromatography of respiratory quinones for microbial community analysis in environmental and biological samples.

PubMed

Hanif, Muhammad; Atsuta, Yoichi; Fujie, Koichi; Daimon, Hiroyuki

2012-03-05

Microbial community structure plays a significant role in environmental assessment and animal health management. The development of a superior analytical strategy for the characterization of microbial community structure is an ongoing challenge. In this study, we developed an effective supercritical fluid extraction (SFE) and ultra performance liquid chromatography (UPLC) method for the analysis of bacterial respiratory quinones (RQ) in environmental and biological samples. RQ profile analysis is one of the most widely used culture-independent tools for characterizing microbial community structure. A UPLC equipped with a photo diode array (PDA) detector was successfully applied to the simultaneous determination of ubiquinones (UQ) and menaquinones (MK) without tedious pretreatment. Supercritical carbon dioxide (scCO(2)) extraction with the solid-phase cartridge trap proved to be a more effective and rapid method for extracting respiratory quinones, compared to a conventional organic solvent extraction method. This methodology leads to a successful analytical procedure that involves a significant reduction in the complexity and sample preparation time. Application of the optimized methodology to characterize microbial communities based on the RQ profile was demonstrated for a variety of environmental samples (activated sludge, digested sludge, and compost) and biological samples (swine and Japanese quail feces).

Meta-Analysis of Coefficient Alpha

ERIC Educational Resources Information Center

Rodriguez, Michael C.; Maeda, Yukiko

2006-01-01

The meta-analysis of coefficient alpha across many studies is becoming more common in psychology by a methodology labeled reliability generalization. Existing reliability generalization studies have not used the sampling distribution of coefficient alpha for precision weighting and other common meta-analytic procedures. A framework is provided for…

Enantiomer fractions of polychlorinated biphenyls in three selected Standard Reference Materials.

PubMed

Morrissey, Joshua A; Bleackley, Derek S; Warner, Nicholas A; Wong, Charles S

2007-01-01

The enantiomer composition of six chiral polychlorinated biphenyls (PCBs) were measured in three different certified Standard Reference Materials (SRMs) from the US National Institute of Standards and Technology (NIST): SRM 1946 (Lake Superior fish tissue), SRM 1939a (PCB Congeners in Hudson River Sediment), and SRM 2978 (organic contaminants in mussel tissue--Raritan Bay, New Jersey) to aid in quality assurance/quality control methodologies in the study of chiral pollutants in sediments and biota. Enantiomer fractions (EFs) of PCBs 91, 95, 136, 149, 174, and 183 were measured using a suite of chiral columns by gas chromatography/mass spectrometry. Concentrations of target analytes were in agreement with certified values. Target analyte EFs in reference materials were measured precisely (<2% relative standard deviation), indicating the utility of SRM in quality assurance/control methodologies for analyses of chiral compounds in environmental samples. Measured EFs were also in agreement with previously published analyses of similar samples, indicating that similar enantioselective processes were taking place in these environmental matrices.

Marine anthropogenic radiotracers in the Southern Hemisphere: New sampling and analytical strategies

NASA Astrophysics Data System (ADS)

Levy, I.; Povinec, P. P.; Aoyama, M.; Hirose, K.; Sanchez-Cabeza, J. A.; Comanducci, J.-F.; Gastaud, J.; Eriksson, M.; Hamajima, Y.; Kim, C. S.; Komura, K.; Osvath, I.; Roos, P.; Yim, S. A.

2011-04-01

The Japan Agency for Marine Earth Science and Technology conducted in 2003-2004 the Blue Earth Global Expedition (BEAGLE2003) around the Southern Hemisphere Oceans, which was a rare opportunity to collect many seawater samples for anthropogenic radionuclide studies. We describe here sampling and analytical methodologies based on radiochemical separations of Cs and Pu from seawater, as well as radiometric and mass spectrometry measurements. Several laboratories took part in radionuclide analyses using different techniques. The intercomparison exercises and analyses of certified reference materials showed a reasonable agreement between the participating laboratories. The obtained data on the distribution of 137Cs and plutonium isotopes in seawater represent the most comprehensive results available for the Southern Hemisphere Oceans.

Surrogate matrix and surrogate analyte approaches for definitive quantitation of endogenous biomolecules.

PubMed

Jones, Barry R; Schultz, Gary A; Eckstein, James A; Ackermann, Bradley L

2012-10-01

Quantitation of biomarkers by LC-MS/MS is complicated by the presence of endogenous analytes. This challenge is most commonly overcome by calibration using an authentic standard spiked into a surrogate matrix devoid of the target analyte. A second approach involves use of a stable-isotope-labeled standard as a surrogate analyte to allow calibration in the actual biological matrix. For both methods, parallelism between calibration standards and the target analyte in biological matrix must be demonstrated in order to ensure accurate quantitation. In this communication, the surrogate matrix and surrogate analyte approaches are compared for the analysis of five amino acids in human plasma: alanine, valine, methionine, leucine and isoleucine. In addition, methodology based on standard addition is introduced, which enables a robust examination of parallelism in both surrogate analyte and surrogate matrix methods prior to formal validation. Results from additional assays are presented to introduce the standard-addition methodology and to highlight the strengths and weaknesses of each approach. For the analysis of amino acids in human plasma, comparable precision and accuracy were obtained by the surrogate matrix and surrogate analyte methods. Both assays were well within tolerances prescribed by regulatory guidance for validation of xenobiotic assays. When stable-isotope-labeled standards are readily available, the surrogate analyte approach allows for facile method development. By comparison, the surrogate matrix method requires greater up-front method development; however, this deficit is offset by the long-term advantage of simplified sample analysis.

Evaluation of analytical methodology for hydrocarbons in high pressure air and nitrogen systems. [data aquisition

NASA Technical Reports Server (NTRS)

1977-01-01

Information regarding the safety limits of hydrocarbons in liquid and gaseous oxygen, the steps taken for hydrocarbon removal from liquified gases, and the analysis of the contaminants was searched and the results are presented. The safety of hydrocarbons in gaseous systems was studied, and the latest hydrocarbon test equipment and methodology is reviewed. A detailed sampling and analysis plan is proposed to evaluate high pressure GN2 and LOX systems.

A novel statistical methodology to overcome sampling irregularities in the forest inventory data and to model forest changes under dynamic disturbance regimes

Treesearch

Nikolay Strigul; Jean Lienard

2015-01-01

Forest inventory datasets offer unprecedented opportunities to model forest dynamics under evolving environmental conditions but they are analytically challenging due to irregular sampling time intervals of the same plot, across the years. We propose here a novel method to model dynamic changes in forest biomass and basal area using forest inventory data. Our...

Hydraulic Fracturing Fluid Analysis for Regulatory Parameters - A Progress Report

EPA Pesticide Factsheets

This presentation is a progress report on the analysis of Hydraulic Fracturing Fluids for regulatory compounds outlined in the various US EPA methodologies. Fracturing fluids vary significantly in consistency and viscosity prior to fracturing. Due to the nature of the fluids the analytical challenges will have to be addressed. This presentation also outlines the sampling issues associated with the collection of dissolved gas samples.

Analytical methodology for sampling and analysing eight siloxanes and trimethylsilanol in biogas from different wastewater treatment plants in Europe.

PubMed

Raich-Montiu, J; Ribas-Font, C; de Arespacochaga, N; Roig-Torres, E; Broto-Puig, F; Crest, M; Bouchy, L; Cortina, J L

2014-02-17

Siloxanes and trimethylsilanol belong to a family of organic silicone compounds that are currently used extensively in industry. Those that are prone to volatilisation become minor compounds in biogas adversely affecting energetic applications. However, non-standard analytical methodologies are available to analyse biogas-based gaseous matrixes. To this end, different sampling techniques (adsorbent tubes, impingers and tedlar bags) were compared using two different configurations: sampling directly from the biogas source or from a 200 L tedlar bag filled with biogas and homogenised. No significant differences were apparent between the two sampling configurations. The adsorbent tubes performed better than the tedlar bags and impingers, particularly for quantifying low concentrations. A method for the speciation of silicon compounds in biogas was developed using gas chromatography coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimised conditions could separate and quantify eight siloxane compounds (L2, L3, L4, L5, D3, D4, D5 and D6) and trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain, France and England was sampled and analysed using the developed methodology. The siloxane concentrations in the biogas samples were influenced by the anaerobic digestion temperature, as well as the nature and composition of the sewage inlet. Siloxanes D4 and D5 were the most abundant, ranging in concentration from 1.5 to 10.1 and 10.8 to 124.0 mg Nm(-3), respectively, and exceeding the tolerance limit of most energy conversion systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of endocrine-disrupting chemicals in human milk by dispersive liquid-liquid microextraction.

PubMed

Vela-Soria, Fernando; Jiménez-Díaz, Inmaculada; Díaz, Caridad; Pérez, José; Iribarne-Durán, Luz María; Serrano-López, Laura; Arrebola, Juan Pedro; Fernández, Mariana Fátima; Olea, Nicolás

2016-09-01

Human populations are widely exposed to numerous so-called endocrine-disrupting chemicals, exogenous compounds able to interfere with the endocrine system. This exposure has been associated with several health disorders. New analytical procedures are needed for biomonitoring these xenobiotics in human matrices. A quick and inexpensive methodological procedure, based on sample treatment by dispersive liquid-liquid microextraction, is proposed for the determination of bisphenols, parabens and benzophenones in samples. LOQs ranged from 0.4 to 0.7 ng ml(-1) and RSDs from 4.3 to 14.8%. This methodology was satisfactorily applied in the simultaneous determination of a wide range of endocrine-disrupting chemicals in human milk samples and is suitable for application in biomonitoring studies.

Tank Vapor Characterization Project: Tank 241-S-102 fourth temporal study: Headspace gas and vapor characterization results from samples collected on December 19, 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pool, K.H.; Evans, J.C.; Olsen, K.B.

1997-08-01

This report presents the results from analyses of samples taken from the headspace of waste storage tank 241-S-102 (Tank S-102) at the Hanford Site in Washington State. Tank headspace samples collected by SGN Eurisys Service Corporation (SESC) were analyzed by Pacific Northwest National Laboratory (PNNL) to determine headspace concentrations of selected non-radioactive analytes. Analyses were performed by the Vapor Analytical Laboratory (VAL) at PNNL. Vapor concentrations from sorbent trap samples are based on measured sample volumes provided by SESC. Ammonia was determined to be above the immediate notification limit of 150 ppm as specified by the sampling and analysis planmore » (SAP). Hydrogen was the principal flammable constituent of the Tank S-102 headspace, determined to be present at approximately 2.410% of its lower flammability limit (LFL). Total headspace flammability was estimated to be <2.973% of its lower flammability limit (LFL). Total headspace flammability was estimated to be <2.973% of the LFL. Average measured concentrations of targeted gases, inorganic vapors, and selected organic vapors are provided in Table S.1. A summary of experimental methods, including sampling methodology, analytical procedures, and quality assurance and control methods are presented in Section 2.0. Detailed descriptions of the analytical results are provided in Section 3.0.« less

Maybe Small Is Too Small a Term: Introduction to Advancing Small Sample Prevention Science.

PubMed

Fok, Carlotta Ching Ting; Henry, David; Allen, James

2015-10-01

Prevention research addressing health disparities often involves work with small population groups experiencing such disparities. The goals of this special section are to (1) address the question of what constitutes a small sample; (2) identify some of the key research design and analytic issues that arise in prevention research with small samples; (3) develop applied, problem-oriented, and methodologically innovative solutions to these design and analytic issues; and (4) evaluate the potential role of these innovative solutions in describing phenomena, testing theory, and evaluating interventions in prevention research. Through these efforts, we hope to promote broader application of these methodological innovations. We also seek whenever possible, to explore their implications in more general problems that appear in research with small samples but concern all areas of prevention research. This special section includes two sections. The first section aims to provide input for researchers at the design phase, while the second focuses on analysis. Each article describes an innovative solution to one or more challenges posed by the analysis of small samples, with special emphasis on testing for intervention effects in prevention research. A concluding article summarizes some of their broader implications, along with conclusions regarding future directions in research with small samples in prevention science. Finally, a commentary provides the perspective of the federal agencies that sponsored the conference that gave rise to this special section.

Temperature-controlled micro-TLC: a versatile green chemistry and fast analytical tool for separation and preliminary screening of steroids fraction from biological and environmental samples.

PubMed

Zarzycki, Paweł K; Slączka, Magdalena M; Zarzycka, Magdalena B; Bartoszuk, Małgorzata A; Włodarczyk, Elżbieta; Baran, Michał J

2011-11-01

This paper is a continuation of our previous research focusing on development of micro-TLC methodology under temperature-controlled conditions. The main goal of present paper is to demonstrate separation and detection capability of micro-TLC technique involving simple analytical protocols without multi-steps sample pre-purification. One of the advantages of planar chromatography over its column counterpart is that each TLC run can be performed using non-previously used stationary phase. Therefore, it is possible to fractionate or separate complex samples characterized by heavy biological matrix loading. In present studies components of interest, mainly steroids, were isolated from biological samples like fish bile using single pre-treatment steps involving direct organic liquid extraction and/or deproteinization by freeze-drying method. Low-molecular mass compounds with polarity ranging from estetrol to progesterone derived from the environmental samples (lake water, untreated and treated sewage waters) were concentrated using optimized solid-phase extraction (SPE). Specific bands patterns for samples derived from surface water of the Middle Pomerania in northern part of Poland can be easily observed on obtained micro-TLC chromatograms. This approach can be useful as simple and non-expensive complementary method for fast control and screening of treated sewage water discharged by the municipal wastewater treatment plants. Moreover, our experimental results show the potential of micro-TLC as an efficient tool for retention measurements of a wide range of steroids under reversed-phase (RP) chromatographic conditions. These data can be used for further optimalization of SPE or HPLC systems working under RP conditions. Furthermore, we also demonstrated that micro-TLC based analytical approach can be applied as an effective method for the internal standard (IS) substance search. Generally, described methodology can be applied for fast fractionation or screening of the whole range of target substances as well as chemo-taxonomic studies and fingerprinting of complex mixtures, which are present in biological or environmental samples. Due to low consumption of eluent (usually 0.3-1mL/run) mainly composed of water-alcohol binary mixtures, this method can be considered as environmentally friendly and green chemistry focused analytical tool, supplementary to analytical protocols involving column chromatography or planar micro-fluidic devices. Copyright © 2011 Elsevier Ltd. All rights reserved.

Multi-center evaluation of analytical performance of the Beckman Coulter AU5822 chemistry analyzer.

PubMed

Zimmerman, M K; Friesen, L R; Nice, A; Vollmer, P A; Dockery, E A; Rankin, J D; Zmuda, K; Wong, S H

2015-09-01

Our three academic institutions, Indiana University, Northwestern Memorial Hospital, and Wake Forest, were among the first in the United States to implement the Beckman Coulter AU5822 series chemistry analyzers. We undertook this post-hoc multi-center study by merging our data to determine performance characteristics and the impact of methodology changes on analyte measurement. We independently completed performance validation studies including precision, linearity/analytical measurement range, method comparison, and reference range verification. Complete data sets were available from at least one institution for 66 analytes with the following groups: 51 from all three institutions, and 15 from 1 or 2 institutions for a total sample size of 12,064. Precision was similar among institutions. Coefficients of variation (CV) were <10% for 97%. Analytes with CVs >10% included direct bilirubin and digoxin. All analytes exhibited linearity over the analytical measurement range. Method comparison data showed slopes between 0.900-1.100 for 87.9% of the analytes. Slopes for amylase, tobramycin and urine amylase were <0.8; the slope for lipase was >1.5, due to known methodology or standardization differences. Consequently, reference ranges of amylase, urine amylase and lipase required only minor or no modification. The four AU5822 analyzers independently evaluated at three sites showed consistent precision, linearity, and correlation results. Since installations, the test results had been well received by clinicians from all three institutions. Copyright © 2015. Published by Elsevier Inc.

1990 National Water Quality Laboratory Services Catalog

USGS Publications Warehouse

Pritt, Jeffrey; Jones, Berwyn E.

1989-01-01

PREFACE This catalog provides information about analytical services available from the National Water Quality Laboratory (NWQL) to support programs of the Water Resources Division of the U.S. Geological Survey. To assist personnel in the selection of analytical services, the catalog lists cost, sample volume, applicable concentration range, detection level, precision of analysis, and preservation techniques for samples to be submitted for analysis. Prices for services reflect operationa1 costs, the complexity of each analytical procedure, and the costs to ensure analytical quality control. The catalog consists of five parts. Part 1 is a glossary of terminology; Part 2 lists the bottles, containers, solutions, and other materials that are available through the NWQL; Part 3 describes the field processing of samples to be submitted for analysis; Part 4 describes analytical services that are available; and Part 5 contains indices of analytical methodology and Chemical Abstract Services (CAS) numbers. Nomenclature used in the catalog is consistent with WATSTORE and STORET. The user is provided with laboratory codes and schedules that consist of groupings of parameters which are measured together in the NWQL. In cases where more than one analytical range is offered for a single element or compound, different laboratory codes are given. Book 5 of the series 'Techniques of Water Resources Investigations of the U.S. Geological Survey' should be consulted for more information about the analytical procedures included in the tabulations. This catalog supersedes U.S. Geological Survey Open-File Report 86-232 '1986-87-88 National Water Quality Laboratory Services Catalog', October 1985.

Testing Crites' Model of Career Maturity: A Hierarchical Strategy.

ERIC Educational Resources Information Center

Wallbrown, Fred H.; And Others

1986-01-01

Investigated the construct validity of Crites' model of career maturity and the Career Maturity Inventory (CMI). Results from a nationwide sample of adolescents, using hierarchical factor analytic methodology, indicated confirmatory support for the multidimensionality of Crites' model of career maturity, and the construct validity of the CMI as a…

Simultaneous stable carbon isotopic analysis of wine glycerol and ethanol by liquid chromatography coupled to isotope ratio mass spectrometry.

PubMed

Cabañero, Ana I; Recio, Jose L; Rupérez, Mercedes

2010-01-27

A novel procedure was established for the simultaneous characterization of wine glycerol and ethanol (13)C/(12)C isotope ratio, using liquid chromatography/isotope ratio mass spectrometry (LC-IRMS). Several parameters influencing separation of glycerol and ethanol from wine matrix were optimized. Results obtained for 35 Spanish samples exposed no significant differences and very strong correlations (r = 0.99) between the glycerol (13)C/(12)C ratios obtained by an alternative method (gas chromatography/isotope ratio mass spectrometry) and the proposed new methodology, and between the ethanol (13)C/(12)C ratios obtained by the official method (elemental analyzer/isotope ratio mass spectrometry) and the proposed new methodology. The accuracy of the proposed method varied from 0.01 to 0.19 per thousand, and the analytical precision was better than 0.25 per thousand. The new developed LC-IRMS method it is the first isotopic method that allows (13)C/(12)C determination of both analytes in the same run directly from a liquid sample with no previous glycerol or ethanol isolation, overcoming technical difficulties associated with complex sample treatment and improving in terms of simplicity and speed.

HPLC-PFD determination of priority pollutant PAHs in water, sediment, and semipermeable membrane devices

USGS Publications Warehouse

Williamson, K.S.; Petty, J.D.; Huckins, J.N.; Lebo, J.A.; Kaiser, E.M.

2002-01-01

High performance liquid chromatography coupled with programmable fluorescence detection was employed for the determination of 15 priority pollutant polycyclic aromatic hydrocarbons (PPPAHs) in water, sediment, and semipermeable membrane devices (SPMDs). Chromatographic separation using this analytical method facilitates selectivity, sensitivity (ppt levels), and can serve as a non-destructive technique for subsequent analysis by other chromatographic and spectroscopic techniques. Extraction and sample cleanup procedures were also developed for water, sediment, and SPMDs using various chromatographic and wet chemical methods. The focus of this publication is to examine the enrichment techniques and the analytical methodologies used in the isolation, characterization, and quantitation of 15 PPPAHs in different sample matrices.

Fast single run of vanilla fingerprint markers on microfluidic-electrochemistry chip for confirmation of common frauds.

PubMed

Avila, Mónica; Zougagh, Mohammed; Escarpa, Alberto; Ríos, Angel

2009-10-01

A new strategy based on the fast separation of the fingerprint markers of Vanilla planifolia extracts and vanilla-related samples on microfluidic-electrochemistry chip is proposed. This methodology allowed the detection of all required markers for confirmation of common frauds in this field. The elution order was strategically connected with sequential sample screening and analyte confirmation steps, where first ethyl vanillin was detected to distinguish natural from adultered samples; second, vanillin as prominent marker in V. planifolia, but frequently added in its synthetic form; and third, the final detection of the fingerprint markers (p-hydroxybenzaldehyde, vanillic acid, and p-hydroxybenzoic acid) of V. planifolia with confirmation purposes. The reliability of the proposed methodology was demonstrated in the confirmation the natural or non-natural origin of vanilla in samples using V. planifolia extracts and other selected food samples containing this flavor.

A novel method for the determination of chemical purity and assay of menaquinone-7. Comparison with the methods from the official USP monograph.

PubMed

Jedynak, Łukasz; Jedynak, Maria; Kossykowska, Magdalena; Zagrodzka, Joanna

2017-02-20

An HPLC method with UV detection and separation with the use of a C30 reversed phase analytical column for the determination of chemical purity and assay of menaquinone-7 (MK7) in one chromatographic run was developed. The method is superior to the methods published in the USP Monograph in terms of selectivity, sensitivity and accuracy, as well as time, solvent and sample consumption. The developed methodology was applied to MK7 samples of active pharmaceutical ingredient (API) purity, MK7 samples of lower quality and crude MK7 samples before purification. The comparison of the results revealed that the use of USP methodology could lead to serious overestimation (up to a few percent) of both purity and MK7 assay in menaquinone-7 samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Diversity of Staphylococcus aureus strains colonizing various niches of the human body.

PubMed

Muenks, Carol E; Hogan, Patrick G; Wang, Jeffrey W; Eisenstein, Kimberly A; Burnham, Carey-Ann D; Fritz, Stephanie A

2016-06-01

As individuals may be colonized with multiple strains of Staphylococcus aureus at different body sites, the objectives of this study were to determine whether S. aureus polyclonal colonization exists within one body niche and the optimal sampling sites and culture methodology to capture the diversity of S. aureus strains in community-dwelling individuals. Swabs were collected from the nares, axillae, and inguinal folds of 3 children with community-associated S. aureus infections and 11 household contacts, all with known S. aureus colonization. S. aureus isolates were recovered from each body niche using 4 culture methods and evaluated for polyclonality using phenotypic and genotypic strain characterization methodologies. Within individuals, the mean (range) number of phenotypes and genotypes was 2.4 (1-4) and 3.1 (1-6), respectively. Six (43%) and 10 (71%) participants exhibited phenotypic and genotypic polyclonality within one body niche, respectively. Broth enrichment yielded the highest analytical sensitivity for S. aureus recovery, while direct plating to blood agar yielded the highest genotypic strain diversity. This study revealed S. aureus polyclonality within a single body niche. Culture methodology and sampling sites influenced the analytical sensitivity of S. aureus colonization detection and the robustness of phenotypic and genotypic strain recovery. Copyright © 2016 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Methodological quality of behavioural weight loss studies: a systematic review

PubMed Central

Lemon, S. C.; Wang, M. L.; Haughton, C. F.; Estabrook, D. P.; Frisard, C. F.; Pagoto, S. L.

2018-01-01

Summary This systematic review assessed the methodological quality of behavioural weight loss intervention studies conducted among adults and associations between quality and statistically significant weight loss outcome, strength of intervention effectiveness and sample size. Searches for trials published between January, 2009 and December, 2014 were conducted using PUBMED, MEDLINE and PSYCINFO and identified ninety studies. Methodological quality indicators included study design, anthropometric measurement approach, sample size calculations, intent-to-treat (ITT) analysis, loss to follow-up rate, missing data strategy, sampling strategy, report of treatment receipt and report of intervention fidelity (mean = 6.3). Indicators most commonly utilized included randomized design (100%), objectively measured anthropometrics (96.7%), ITT analysis (86.7%) and reporting treatment adherence (76.7%). Most studies (62.2%) had a follow-up rate >75% and reported a loss to follow-up analytic strategy or minimal missing data (69.9%). Describing intervention fidelity (34.4%) and sampling from a known population (41.1%) were least common. Methodological quality was not associated with reporting a statistically significant result, effect size or sample size. This review found the published literature of behavioural weight loss trials to be of high quality for specific indicators, including study design and measurement. Identified for improvement include utilization of more rigorous statistical approaches to loss to follow up and better fidelity reporting. PMID:27071775

Solid sorbent air sampling and analytical procedure for methyl-, dimethyl-, ethyl-, and diethylamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elskamp, C.J.; Schultz, G.R.

1986-01-01

A sampling and analytical procedure for methyl-, dimethyl-, ethyl-, and diethylamine was developed in order to avoid problems typically encountered in the sampling and analysis of low molecular weight aliphatic amines. Samples are collected with adsorbent tubes containing Amberlite XAD-7 resin coated with the derivatizing reagent, NBD chloride (7-chloro-4-nitrobenzo-2-oxa-1,3-diazole). Analysis is performed by high performance liquid chromatography with the use of a fluorescence and/or UV/visible detector. All four amines can be monitored simultaneously, and neither collection nor storage is affected by humidity. Samples are stable at room temperature for at least two weeks. The methodology has been tested for eachmore » of the four amines at sample loadings equivalent to air concentration ranges of 0.5 to 30 ppm for a sample volume of 10 liters. The method shows promise for determining other airborne primary and secondary low molecular weight aliphatic amines.« less

Gas chromatography coupled to tunable pulsed glow discharge time-of-flight mass spectrometry for environmental analysis.

PubMed

Solà-Vázquez, Auristela; Lara-Gonzalo, Azucena; Costa-Fernández, José M; Pereiro, Rosario; Sanz-Medel, Alfredo

2010-05-01

A tuneable microsecond pulsed direct current glow discharge (GD)-time-of-flight mass spectrometer MS(TOF) developed in our laboratory was coupled to a gas chromatograph (GC) to obtain sequential collection of the mass spectra, at different temporal regimes occurring in the GD pulses, during elution of the analytes. The capabilities of this set-up were explored using a mixture of volatile organic compounds of environmental concern: BrClCH, Cl(3)CH, Cl(4)C, BrCl(2)CH, Br(2)ClCH, Br(3)CH. The experimental parameters of the GC-pulsed GD-MS(TOF) prototype were optimized in order to separate appropriately and analyze the six selected organic compounds, and two GC carrier gases, helium and nitrogen, were evaluated. Mass spectra for all analytes were obtained in the prepeak, plateau and afterpeak temporal regimes of the pulsed GD. Results showed that helium offered the best elemental sensitivity, while nitrogen provided higher signal intensities for fragments and molecular peaks. The analytical performance characteristics were also worked out for each analyte. Absolute detection limits obtained were in the order of ng. In a second step, headspace solid phase microextraction (HS SPME), as sample preparation and preconcentration technique, was evaluated for the quantification of the compounds under study, in order to achieve the required analytical sensitivity for trihalomethanes European Union (EU) environmental legislation. The analytical figures of merit obtained using the proposed methodology showed rather good detection limits (between 2 and 13 microg L(-1) depending on the analyte). In fact, the developed methodology met the EU legislation requirements (the maximum level permitted in tap water for the "total trihalomethanes" is set at 100 microg L(-1)). Real analysis of drinking water and river water were successfully carried out. To our knowledge this is the first application of GC-pulsed GD-MS(TOF) for the analysis of real samples. Its ability to provide elemental, fragments and molecular information of the organic compounds is demonstrated.

High-throughput analysis using non-depletive SPME: challenges and applications to the determination of free and total concentrations in small sample volumes.

PubMed

Boyacı, Ezel; Bojko, Barbara; Reyes-Garcés, Nathaly; Poole, Justen J; Gómez-Ríos, Germán Augusto; Teixeira, Alexandre; Nicol, Beate; Pawliszyn, Janusz

2018-01-18

In vitro high-throughput non-depletive quantitation of chemicals in biofluids is of growing interest in many areas. Some of the challenges facing researchers include the limited volume of biofluids, rapid and high-throughput sampling requirements, and the lack of reliable methods. Coupled to the above, growing interest in the monitoring of kinetics and dynamics of miniaturized biosystems has spurred the demand for development of novel and revolutionary methodologies for analysis of biofluids. The applicability of solid-phase microextraction (SPME) is investigated as a potential technology to fulfill the aforementioned requirements. As analytes with sufficient diversity in their physicochemical features, nicotine, N,N-Diethyl-meta-toluamide, and diclofenac were selected as test compounds for the study. The objective was to develop methodologies that would allow repeated non-depletive sampling from 96-well plates, using 100 µL of sample. Initially, thin film-SPME was investigated. Results revealed substantial depletion and consequent disruption in the system. Therefore, new ultra-thin coated fibers were developed. The applicability of this device to the described sampling scenario was tested by determining the protein binding of the analytes. Results showed good agreement with rapid equilibrium dialysis. The presented method allows high-throughput analysis using small volumes, enabling fast reliable free and total concentration determinations without disruption of system equilibrium.

Comprehensive analytical methodology to determine hydrocarbons in marine waters using extraction disks coupled to glass fiber filters and compound-specific isotope analyses.

PubMed

Ternon, Eva; Tolosa, Imma

2015-07-24

Solid-phase extraction of both aliphatic (AHs) and aromatic polycyclic hydrocarbons (PAHs) from seawater samples was evaluated using a GFF filter stacked upon an octadecyl bonded silica (C18) disk. Stable-isotope measurements were developed on hydrocarbons extracted from both GFF and C18-disks in order to characterize the source of hydrocarbons. A clear partition of hydrocarbon compounds between the dissolved and the particulate phase was highlighted. PAHs showed a higher affinity with the dissolved phase (recoveries efficiency of 48-71%) whereas AHs presented strong affinity with the particulate phase (up to 76% of extraction efficiency). Medium volumes of seawater samples were tested and no breakthrough was observed for a 5L sample. Isotopic fractionation was investigated within all analytical steps but none was evidenced. This method has been applied to harbor seawater samples and very low AH and PAH concentrations were achieved. Due to the low concentration levels of hydrocarbons in the samples, the source of hydrocarbons was determined by molecular indices rather than isotopic measurements and a pyrolytic origin was evidenced. The aliphatic profile also revealed the presence of long-chain linear alkylbenzenes (LABs). The methodology presented here would better fit to polluted coastal environments affected by recent oil spills. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitation of DNA adducts by stable isotope dilution mass spectrometry

PubMed Central

Tretyakova, Natalia; Goggin, Melissa; Janis, Gregory

2012-01-01

Exposure to endogenous and exogenous chemicals can lead to the formation of structurally modified DNA bases (DNA adducts). If not repaired, these nucleobase lesions can cause polymerase errors during DNA replication, leading to heritable mutations potentially contributing to the development of cancer. Due to their critical role in cancer initiation, DNA adducts represent mechanism-based biomarkers of carcinogen exposure, and their quantitation is particularly useful for cancer risk assessment. DNA adducts are also valuable in mechanistic studies linking tumorigenic effects of environmental and industrial carcinogens to specific electrophilic species generated from their metabolism. While multiple experimental methodologies have been developed for DNA adduct analysis in biological samples – including immunoassay, HPLC, and 32P-postlabeling – isotope dilution high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) generally has superior selectivity, sensitivity, accuracy, and reproducibility. As typical DNA adducts concentrations in biological samples are between 0.01 – 10 adducts per 108 normal nucleotides, ultrasensitive HPLC-ESI-MS/MS methodologies are required for their analysis. Recent developments in analytical separations and biological mass spectrometry – especially nanoflow HPLC, nanospray ionization MS, chip-MS, and high resolution MS – have pushed the limits of analytical HPLC-ESI-MS/MS methodologies for DNA adducts, allowing researchers to accurately measure their concentrations in biological samples from patients treated with DNA alkylating drugs and in populations exposed to carcinogens from urban air, drinking water, cooked food, alcohol, and cigarette smoke. PMID:22827593

Quantitative Determination of Noa (Naturally Occurring Asbestos) in Rocks : Comparison Between Pcom and SEM Analysis

NASA Astrophysics Data System (ADS)

Baietto, Oliviero; Amodeo, Francesco; Giorgis, Ilaria; Vitaliti, Martina

2017-04-01

The quantification of NOA (Naturally Occurring Asbestos) in a rock or soil matrix is complex and subject to numerous errors. The purpose of this study is to compare two fundamental methodologies used for the analysis: the first one uses Phase Contrast Optical Microscope (PCOM) while the second one uses Scanning Electron Microscope (SEM). The two methods, although they provide the same result, which is the asbestos mass to total mass ratio, have completely different characteristics and both present pros and cons. The current legislation in Italy involves the use of SEM, DRX, FTIR, PCOM (DM 6/9/94) for the quantification of asbestos in bulk materials and soils and the threshold beyond which the material is considered as hazardous waste is a concentration of asbestos fiber of 1000 mg/kg.(DM 161/2012). The most used technology is the SEM which is the one among these with the better analytical sensitivity.(120mg/Kg DM 6 /9/94) The fundamental differences among the analyses are mainly: - Amount of analyzed sample portion - Representativeness of the sample - Resolution - Analytical precision - Uncertainty of the methodology - Operator errors Due to the problem of quantification of DRX and FTIR (1% DM 6/9/94) our Asbestos Laboratory (DIATI POLITO) since more than twenty years apply the PCOM methodology and in the last years the SEM methodology for quantification of asbestos content. The aim of our research is to compare the results obtained from a PCOM analysis with the results provided by SEM analysis on the base of more than 100 natural samples both from cores (tunnel-boring or explorative-drilling) and from tunnelling excavation . The results obtained show, in most cases, a good correlation between the two techniques. Of particular relevance is the fact that both techniques are reliable for very low quantities of asbestos, even lower than the analytical sensitivity. This work highlights the comparison between the two techniques emphasizing strengths and weaknesses of the two procedures and suggests how an integrated approach, together with the skills and experience of the operator may be the best way forward in order to obtain a constructive improvement of analysis techniques.

Analytical methods in sphingolipidomics: Quantitative and profiling approaches in food analysis.

PubMed

Canela, Núria; Herrero, Pol; Mariné, Sílvia; Nadal, Pedro; Ras, Maria Rosa; Rodríguez, Miguel Ángel; Arola, Lluís

2016-01-08

In recent years, sphingolipidomics has emerged as an interesting omic science that encompasses the study of the full sphingolipidome characterization, content, structure and activity in cells, tissues or organisms. Like other omics, it has the potential to impact biomarker discovery, drug development and systems biology knowledge. Concretely, dietary food sphingolipids have gained considerable importance due to their extensively reported bioactivity. Because of the complexity of this lipid family and their diversity among foods, powerful analytical methodologies are needed for their study. The analytical tools developed in the past have been improved with the enormous advances made in recent years in mass spectrometry (MS) and chromatography, which allow the convenient and sensitive identification and quantitation of sphingolipid classes and form the basis of current sphingolipidomics methodologies. In addition, novel hyphenated nuclear magnetic resonance (NMR) strategies, new ionization strategies, and MS imaging are outlined as promising technologies to shape the future of sphingolipid analyses. This review traces the analytical methods of sphingolipidomics in food analysis concerning sample extraction, chromatographic separation, the identification and quantification of sphingolipids by MS and their structural elucidation by NMR. Copyright © 2015 Elsevier B.V. All rights reserved.

4-Nonylphenol (NP) in food-contact materials: analytical methodology and occurrence.

PubMed

Fernandes, A R; Rose, M; Charlton, C

2008-03-01

Nonylphenol is a recognized environmental contaminant, but it is unclear whether its occurrence in food arises only through environmental pathways or also during the processing or packaging of food, as there are reports that indicate that materials in contact with food such as rubber products and polyvinylchloride wraps can contain nonylphenol. A review of the literature has highlighted the scarcity of robust analytical methodology or data on the occurrence of nonylphenol in packaging materials. This paper describes a methodology for the determination of nonylphenol in a variety of packaging materials, which includes plastics, paper and rubber. The method uses either Soxhlet extraction or dissolution followed by solvent extraction (depending on the material type), followed by purification using adsorption chromatography. Procedures were internally standardized using 13C-labelled nonylphenol and the analytes were measured by gas chromatography-mass spectrometry. The method is validated and data relating to quality parameters such as limits of detection, recovery, precision and linearity of measurement are provided. Analysis of a range of 25 food-contact materials found nonylphenol at concentrations of 64-287 microg g(-1) in some polystyrene and polyvinylchloride samples. Far lower concentrations (<0.03-1.4 microg g(-1)) were detected in the other materials. It is possible that occurrence at the higher levels has the potential for migration to food.

New approaches to wipe sampling methods for antineoplastic and other hazardous drugs in healthcare settings.

PubMed

Connor, Thomas H; Smith, Jerome P

2016-09-01

At the present time, the method of choice to determine surface contamination of the workplace with antineoplastic and other hazardous drugs is surface wipe sampling and subsequent sample analysis with a variety of analytical techniques. The purpose of this article is to review current methodology for determining the level of surface contamination with hazardous drugs in healthcare settings and to discuss recent advances in this area. In addition it will provide some guidance for conducting surface wipe sampling and sample analysis for these drugs in healthcare settings. Published studies on the use of wipe sampling to measure hazardous drugs on surfaces in healthcare settings drugs were reviewed. These studies include the use of well-documented chromatographic techniques for sample analysis in addition to newly evolving technology that provides rapid analysis of specific antineoplastic. Methodology for the analysis of surface wipe samples for hazardous drugs are reviewed, including the purposes, technical factors, sampling strategy, materials required, and limitations. The use of lateral flow immunoassay (LFIA) and fluorescence covalent microbead immunosorbent assay (FCMIA) for surface wipe sample evaluation is also discussed. Current recommendations are that all healthc a re settings where antineoplastic and other hazardous drugs are handled include surface wipe sampling as part of a comprehensive hazardous drug-safe handling program. Surface wipe sampling may be used as a method to characterize potential occupational dermal exposure risk and to evaluate the effectiveness of implemented controls and the overall safety program. New technology, although currently limited in scope, may make wipe sampling for hazardous drugs more routine, less costly, and provide a shorter response time than classical analytical techniques now in use.

Automation of static and dynamic non-dispersive liquid phase microextraction. Part 1: Approaches based on extractant drop-, plug-, film- and microflow-formation.

PubMed

Alexovič, Michal; Horstkotte, Burkhard; Solich, Petr; Sabo, Ján

2016-02-04

Simplicity, effectiveness, swiftness, and environmental friendliness - these are the typical requirements for the state of the art development of green analytical techniques. Liquid phase microextraction (LPME) stands for a family of elegant sample pretreatment and analyte preconcentration techniques preserving these principles in numerous applications. By using only fractions of solvent and sample compared to classical liquid-liquid extraction, the extraction kinetics, the preconcentration factor, and the cost efficiency can be increased. Moreover, significant improvements can be made by automation, which is still a hot topic in analytical chemistry. This review surveys comprehensively and in two parts the developments of automation of non-dispersive LPME methodologies performed in static and dynamic modes. Their advantages and limitations and the reported analytical performances are discussed and put into perspective with the corresponding manual procedures. The automation strategies, techniques, and their operation advantages as well as their potentials are further described and discussed. In this first part, an introduction to LPME and their static and dynamic operation modes as well as their automation methodologies is given. The LPME techniques are classified according to the different approaches of protection of the extraction solvent using either a tip-like (needle/tube/rod) support (drop-based approaches), a wall support (film-based approaches), or microfluidic devices. In the second part, the LPME techniques based on porous supports for the extraction solvent such as membranes and porous media are overviewed. An outlook on future demands and perspectives in this promising area of analytical chemistry is finally given. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative SIMS Imaging of Agar-Based Microbial Communities.

PubMed

Dunham, Sage J B; Ellis, Joseph F; Baig, Nameera F; Morales-Soto, Nydia; Cao, Tianyuan; Shrout, Joshua D; Bohn, Paul W; Sweedler, Jonathan V

2018-05-01

After several decades of widespread use for mapping elemental ions and small molecular fragments in surface science, secondary ion mass spectrometry (SIMS) has emerged as a powerful analytical tool for molecular imaging in biology. Biomolecular SIMS imaging has primarily been used as a qualitative technique; although the distribution of a single analyte can be accurately determined, it is difficult to map the absolute quantity of a compound or even to compare the relative abundance of one molecular species to that of another. We describe a method for quantitative SIMS imaging of small molecules in agar-based microbial communities. The microbes are cultivated on a thin film of agar, dried under nitrogen, and imaged directly with SIMS. By use of optical microscopy, we show that the area of the agar is reduced by 26 ± 2% (standard deviation) during dehydration, but the overall biofilm morphology and analyte distribution are largely retained. We detail a quantitative imaging methodology, in which the ion intensity of each analyte is (1) normalized to an external quadratic regression curve, (2) corrected for isomeric interference, and (3) filtered for sample-specific noise and lower and upper limits of quantitation. The end result is a two-dimensional surface density image for each analyte. The sample preparation and quantitation methods are validated by quantitatively imaging four alkyl-quinolone and alkyl-quinoline N-oxide signaling molecules (including Pseudomonas quinolone signal) in Pseudomonas aeruginosa colony biofilms. We show that the relative surface densities of the target biomolecules are substantially different from values inferred through direct intensity comparison and that the developed methodologies can be used to quantitatively compare as many ions as there are available standards.

Estimating Children’s Soil/Dust Ingestion Rates through Retrospective Analyses of Blood Lead Biomonitoring from the Bunker Hill Superfund Site in Idaho

EPA Science Inventory

Background: Soil/dust ingestion rates are important variables in assessing children’s health risks in contaminated environments. Current estimates are based largely on soil tracer methodology, which is limited by analytical uncertainty, small sample size, and short study du...

Linking Teacher Competences to Organizational Citizenship Behaviour: The Role of Empowerment

ERIC Educational Resources Information Center

Kasekende, Francis; Munene, John C.; Otengei, Samson Omuudu; Ntayi, Joseph Mpeera

2016-01-01

Purpose: The purpose of this paper is to examine relationship between teacher competences and organizational citizenship behavior (OCB) with empowerment as a mediating factor. Design/methodology/approach: The study took a cross-sectional descriptive and analytical design. Using cluster and random sampling procedures, data were obtained from 383…

Development of Sample Handling and Analytical Expertise For the Stardust Comet Sample Return

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, J; Bajt, S; Brennan, S

NASA's Stardust mission returned to Earth in January 2006 with ''fresh'' cometary particles from a young Jupiter family comet. The cometary particles were sampled during the spacecraft flyby of comet 81P/Wild-2 in January 2004, when they impacted low-density silica aerogel tiles and aluminum foils on the sample tray assembly at approximately 6.1 km/s. This LDRD project has developed extraction and sample recovery methodologies to maximize the scientific information that can be obtained from the analysis of natural and man-made nano-materials of relevance to the LLNL programs.

A LITERATURE REVIEW OF WIPE SAMPLING METHODS ...

EPA Pesticide Factsheets

Wipe sampling is an important technique for the estimation of contaminant deposition in buildings, homes, or outdoor surfaces as a source of possible human exposure. Numerousmethods of wipe sampling exist, and each method has its own specification for the type of wipe, wetting solvent, and determinative step to be used, depending upon the contaminant of concern. The objective of this report is to concisely summarize the findings of a literature review that was conducted to identify the state-of-the-art wipe sampling techniques for a target list of compounds. This report describes the methods used to perform the literature review; a brief review of wipe sampling techniques in general; an analysis of physical and chemical properties of each target analyte; an analysis of wipe sampling techniques for the target analyte list; and asummary of the wipe sampling techniques for the target analyte list, including existing data gaps. In general, no overwhelming consensus can be drawn from the current literature on how to collect a wipe sample for the chemical warfare agents, organophosphate pesticides, and other toxic industrial chemicals of interest to this study. Different methods, media, and wetting solvents have been recommended and used by various groups and different studies. For many of the compounds of interest, no specific wipe sampling methodology has been established for their collection. Before a wipe sampling method (or methods) can be established for the co

A Big Data Analytics Methodology Program in the Health Sector

ERIC Educational Resources Information Center

Lawler, James; Joseph, Anthony; Howell-Barber, H.

2016-01-01

The benefits of Big Data Analytics are cited frequently in the literature. However, the difficulties of implementing Big Data Analytics can limit the number of organizational projects. In this study, the authors evaluate business, procedural and technical factors in the implementation of Big Data Analytics, applying a methodology program. Focusing…

Validation of Rapid Radiochemical Method for Californium ...

EPA Pesticide Factsheets

Technical Brief In the event of a radiological/nuclear contamination event, the response community would need tools and methodologies to rapidly assess the nature and the extent of contamination. To characterize a radiologically contaminated outdoor area and to inform risk assessment, large numbers of environmental samples would be collected and analyzed over a short period of time. To address the challenge of quickly providing analytical results to the field, the U.S. EPA developed a robust analytical method. This method allows response officials to characterize contaminated areas and to assess the effectiveness of remediation efforts, both rapidly and accurately, in the intermediate and late phases of environmental cleanup. Improvement in sample processing and analysis leads to increased laboratory capacity to handle the analysis of a large number of samples following the intentional or unintentional release of a radiological/nuclear contaminant.

Selected reaction monitoring mass spectrometry: a methodology overview.

PubMed

Ebhardt, H Alexander

2014-01-01

Moving past the discovery phase of proteomics, the term targeted proteomics combines multiple approaches investigating a certain set of proteins in more detail. One such targeted proteomics approach is the combination of liquid chromatography and selected or multiple reaction monitoring mass spectrometry (SRM, MRM). SRM-MS requires prior knowledge of the fragmentation pattern of peptides, as the presence of the analyte in a sample is determined by measuring the m/z values of predefined precursor and fragment ions. Using scheduled SRM-MS, many analytes can robustly be monitored allowing for high-throughput sample analysis of the same set of proteins over many conditions. In this chapter, fundaments of SRM-MS are explained as well as an optimized SRM pipeline from assay generation to data analyzed.

Variable-centered and person-centered approaches to studying Mexican-origin mother-daughter cultural orientation dissonance.

PubMed

Bámaca-Colbert, Mayra Y; Gayles, Jochebed G

2010-11-01

The overall aim of the current study was to identify the methodological approach and corresponding analytic procedure that best elucidated the associations among Mexican-origin mother-daughter cultural orientation dissonance, family functioning, and adolescent adjustment. To do so, we employed, and compared, two methodological approaches (i.e., variable-centered and person-centered) via four analytic procedures (i.e., difference score, interactive, matched/mismatched grouping, and latent profiles). The sample consisted of 319 girls in the 7th or 10th grade and their mother or mother figure from a large Southwestern, metropolitan area in the US. Family factors were found to be important predictors of adolescent adjustment in all models. Although some findings were similar across all models, overall, findings suggested that the latent profile procedure best elucidated the associations among the variables examined in this study. In addition, associations were present across early and middle adolescents, with a few findings being only present for one group. Implications for using these analytic procedures in studying cultural and family processes are discussed.

Big Data Analytics Methodology in the Financial Industry

ERIC Educational Resources Information Center

Lawler, James; Joseph, Anthony

2017-01-01

Firms in industry continue to be attracted by the benefits of Big Data Analytics. The benefits of Big Data Analytics projects may not be as evident as frequently indicated in the literature. The authors of the study evaluate factors in a customized methodology that may increase the benefits of Big Data Analytics projects. Evaluating firms in the…

Fire Safety Aspects of Polymeric Materials. Volume 3. Smoke and Toxicity (Combustion Toxicology of Polymers)

DTIC Science & Technology

1978-01-01

Analytical Test Methodology Sampling and analysis of thermal decomposition products are formidable tasks (Rasbash, 1967; Gaskill, 1973; Bankston ...by a flowing solution. A Sample Gas Inlet B Alkali Solution Inlet C Gas and Solution Outlet D Specific Ion Electrode E Reference Electrode E D 1 0 1 2...of radiant heat (Zinn, Powell, Cassanova and Bankston , 1977) ° Seader and Ou have recently proposed a theory relating optical density to particulate

Single-particle mineralogy of Chinese soil particles by the combined use of low-Z particle electron probe X-ray microanalysis and attenuated total reflectance-FT-IR imaging techniques.

PubMed

Malek, Md Abdul; Kim, Bowha; Jung, Hae-Jin; Song, Young-Chul; Ro, Chul-Un

2011-10-15

Our previous work on the speciation of individual mineral particles of micrometer size by the combined use of attenuated total reflectance FT-IR (ATR-FT-IR) imaging and a quantitative energy-dispersive electron probe X-ray microanalysis technique (EPMA), low-Z particle EPMA, demonstrated that the combined use of these two techniques is a powerful approach for looking at the single-particle mineralogy of externally heterogeneous minerals. In this work, this analytical methodology was applied to characterize six soil samples collected at arid areas in China, in order to identify mineral types present in the samples. The six soil samples were collected from two types of soil, i.e., loess and desert soils, for which overall 665 particles were analyzed on a single particle basis. The six soil samples have different mineralogical characteristics, which were clearly differentiated in this work. As this analytical methodology provides complementary information, the ATR-FT-IR imaging on mineral types, and low-Z particle EPMA on the morphology and elemental concentrations, on the same individual particles, more detailed information can be obtained using this approach than when either low-Z particle EPMA or ATR-FT-IR imaging techniques are used alone, which has a great potential for the characterization of Asian dust and mineral dust particles. © 2011 American Chemical Society

ON-SITE SOLID PHRASE EXTRACTION AND LABORATORY ...

EPA Pesticide Factsheets

Fragrance materials, such as synthetic musks in aqueous samples, are normally analyzed by GC/MS in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. A I -L sample, however, usually provides too little analyte for full-scan data acquisition. An on-site extraction method for extracting synthetic musks from 60 L of wastewater effluent has been developed. Such a large sample volume permits high-quality, full-scan mass spectra to be obtained for various synthetic musk compounds. Quantification of these compounds was conveniently achieved from the full-scan data directly, without preparing SIM descriptors for each compound to acquire SIM data. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and more in-depth coverage of each project. Briefly, each project's objective is stated below.Subtask 1: To integrate state-of-the-art technologies (polar organic chemical integrative samplers, advanced solid-phase extraction methodologies with liquid chromatography/electrospray/mass spectrometry) and apply them to studying the sources and fate of a select list of PPCPs. Application and improvement of analytical methodologies that can detect non-volatile, polar, water-sol

IN SITU SOLID-PHASE EXTRACTION AND ANALYSIS OF ...

EPA Pesticide Factsheets

Fragrance materials, such as synthetic musks in aqueous samples, are normally analyzed by GC/MS in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of 1-L samples. A 1-L sample, however, usually provides too little analyte for full-scan data acquisition.We have developed an on-site extraction method for extracting synthetic musks from 60 L of wastewater effluent. Such a large sample volume permits high-quality, full-scan mass spectra to be obtained for various synthetic musk compounds. Quantification of these compounds was conveniently achieved from the full-scan data directly, without preparing SIM descriptors for each compound to acquire SIM data. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and more in-depth coverage of each project. Briefly, each project's objective is stated below.Subtask 1: To integrate state-of-the-art technologies (polar organic chemical integrative samplers, advanced solid-phase extraction methodologies with liquid chromatography/electrospray/mass spectrometry) and apply them to studying the sources and fate of a select list of PPCPs. Application and improvement of analytical methodologies that can detect non-volatile, polar, water-s

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikonomou, M.G.; Crewe, N.F.; Fischer, M.

It has been demonstrated that marine mammals accumulate high concentrations of lipophilic organochlorine contaminants in blubber. As predators of the high trophic level they have also been used to evaluate contamination in the marine environment. Sampling of living marine mammals using a microsample (100 to 200 mg) biopsy dart technique offers a potentially invaluable chronicle in assessing levels and types of persistent environmental pollutants from a sample in which age, sex and other genetic information can additionally be ascertained. The authors have explored analytical methodology based on a high sensitivity detection system (HRGC/HRMS) which provides multi-residue determinations from biopsy dartmore » microsamples. Lipid content and the concentrations of PCDDs, PCDFs and non-ortho and mono-ortho substituted PCBs were measured in 100 mg biopsy dart replicates taken from a killer whale carcass and in three strata of the blubber of that carcass. Statistically acceptable results were obtained from the dart replicates which compared very well with those of the blubber strata. Analytical data from 100 mg extractions from an established in house blubber CRM also compared well against a series of 2.5 g extractions of that CRM. The extraction and cleanup procedures used also allow for the determination of other organohalogen contaminants such as DDT and other pesticides, all the remaining PCBs, polychlorinated diphenylethers and brominated residues. The strengths and limitations of the analytical methodology and the biopsy dart as a sampling tool and pollution predicator will be illustrated in terms of method accuracy and precision, glassware and procedural blanks associated with each extraction batch, and the incorporation of an in house micro reference standard.« less

Handling Missing Data in Educational Research Using SPSS

ERIC Educational Resources Information Center

Cheema, Jehanzeb

2012-01-01

This study looked at the effect of a number of factors such as the choice of analytical method, the handling method for missing data, sample size, and proportion of missing data, in order to evaluate the effect of missing data treatment on accuracy of estimation. In order to accomplish this a methodological approach involving simulated data was…

40 CFR 141.23 - Inorganic chemical sampling and analytical requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Inorganic Contaminants Contaminant MCL (mg/l) Methodology Detection limit (mg/l) Antimony 0.006 Atomic... January 23, 2006. Unit then, the MCL is 0.05 mg/L. 7 The MDL reported for EPA method 200.9 (Atomic... higher. Using multiple depositions, EPA 200.9 is capable of obtaining MDL of 0.0001 mg/L. 8 Using...

Rock-forming and rare elements in lunar surface material from the Sea of Tranquillity and the Ocean of Storms

NASA Technical Reports Server (NTRS)

Shevaleyevskiy, I. D.; Chupakhin, M. S.

1974-01-01

Methodological and analytical capabilities associated with spark mass spectrometry and X-ray spectroscopy are presented for the determination of the elemental composition of samples of lunar regolith returned to the earth by Apollo 11 and Apollo 12. Using X-ray spectroscopy, the main constituents of samples of lunar surface material were determined, and using mass spectrometry -- the main admixtures. The principal difference of Apollo 11 samples from Apollo 12 samples was found for elements contained in microconcentrations. This is especially true of rare earth elements.

The importance of quality control in validating concentrations ...

EPA Pesticide Factsheets

A national-scale survey of 247 contaminants of emerging concern (CECs), including organic and inorganic chemical compounds, and microbial contaminants, was conducted in source and treated drinking water samples from 25 treatment plants across the United States. Multiple methods were used to determine these CECs, including six analytical methods to measure 174 pharmaceuticals, personal care products, and pesticides. A three-component quality assurance/quality control (QA/QC) program was designed for the subset of 174 CECs which allowed us to assess and compare performances of the methods used. The three components included: 1) a common field QA/QC protocol and sample design, 2) individual investigator-developed method-specific QA/QC protocols, and 3) a suite of 46 method comparison analytes that were determined in two or more analytical methods. Overall method performance for the 174 organic chemical CECs was assessed by comparing spiked recoveries in reagent, source, and treated water over a two-year period. In addition to the 247 CECs reported in the larger drinking water study, another 48 pharmaceutical compounds measured did not consistently meet predetermined quality standards. Methodologies that did not seem suitable for these analytes are overviewed. The need to exclude analytes based on method performance demonstrates the importance of additional QA/QC protocols. This paper compares the method performance of six analytical methods used to measure 174 emer

"Reagentless" flow injection determination of ammonia and urea using membrane separation and solid phase basification

NASA Technical Reports Server (NTRS)

Akse, J. R.; Thompson, J. O.; Sauer, R. L.; Atwater, J. E.

1998-01-01

Flow injection analysis instrumentation and methodology for the determination of ammonia and ammonium ions in an aqueous solution are described. Using in-line solid phase basification beds containing crystalline media. the speciation of ammoniacal nitrogen is shifted toward the un-ionized form. which diffuses in the gas phase across a hydrophobic microporous hollow fiber membrane into a pure-water-containing analytical stream. The two streams flow in a countercurrent configuration on opposite sides of the membrane. The neutral pH of the analytical stream promotes the formation of ammonium cations, which are detected using specific conductance. The methodology provides a lower limit of detection of 10 microgram/L and a dynamic concentration range spanning three orders of magnitude using a 315-microliters sample injection volume. Using immobilized urease to enzymatically promote the hydrolysis of urea to produce ammonia and carbon dioxide, the technique has been extended to the determination of urea.

Development of Gold Standard Ion-Selective Electrode-Based Methods for Fluoride Analysis

PubMed Central

Martínez-Mier, E.A.; Cury, J.A.; Heilman, J.R.; Katz, B.P.; Levy, S.M.; Li, Y.; Maguire, A.; Margineda, J.; O’Mullane, D.; Phantumvanit, P.; Soto-Rojas, A.E.; Stookey, G.K.; Villa, A.; Wefel, J.S.; Whelton, H.; Whitford, G.M.; Zero, D.T.; Zhang, W.; Zohouri, V.

2011-01-01

Background/Aims: Currently available techniques for fluoride analysis are not standardized. Therefore, this study was designed to develop standardized methods for analyzing fluoride in biological and nonbiological samples used for dental research. Methods A group of nine laboratories analyzed a set of standardized samples for fluoride concentration using their own methods. The group then reviewed existing analytical techniques for fluoride analysis, identified inconsistencies in the use of these techniques and conducted testing to resolve differences. Based on the results of the testing undertaken to define the best approaches for the analysis, the group developed recommendations for direct and microdiffusion methods using the fluoride ion-selective electrode. Results Initial results demonstrated that there was no consensus regarding the choice of analytical techniques for different types of samples. Although for several types of samples, the results of the fluoride analyses were similar among some laboratories, greater differences were observed for saliva, food and beverage samples. In spite of these initial differences, precise and true values of fluoride concentration, as well as smaller differences between laboratories, were obtained once the standardized methodologies were used. Intraclass correlation coefficients ranged from 0.90 to 0.93, for the analysis of a certified reference material, using the standardized methodologies. Conclusion The results of this study demonstrate that the development and use of standardized protocols for F analysis significantly decreased differences among laboratories and resulted in more precise and true values. PMID:21160184

The importance of quality control in validating concentrations of contaminants of emerging concern in source and treated drinking water samples.

PubMed

Batt, Angela L; Furlong, Edward T; Mash, Heath E; Glassmeyer, Susan T; Kolpin, Dana W

2017-02-01

A national-scale survey of 247 contaminants of emerging concern (CECs), including organic and inorganic chemical compounds, and microbial contaminants, was conducted in source and treated drinking water samples from 25 treatment plants across the United States. Multiple methods were used to determine these CECs, including six analytical methods to measure 174 pharmaceuticals, personal care products, and pesticides. A three-component quality assurance/quality control (QA/QC) program was designed for the subset of 174 CECs which allowed us to assess and compare performances of the methods used. The three components included: 1) a common field QA/QC protocol and sample design, 2) individual investigator-developed method-specific QA/QC protocols, and 3) a suite of 46 method comparison analytes that were determined in two or more analytical methods. Overall method performance for the 174 organic chemical CECs was assessed by comparing spiked recoveries in reagent, source, and treated water over a two-year period. In addition to the 247 CECs reported in the larger drinking water study, another 48 pharmaceutical compounds measured did not consistently meet predetermined quality standards. Methodologies that did not seem suitable for these analytes are overviewed. The need to exclude analytes based on method performance demonstrates the importance of additional QA/QC protocols. Published by Elsevier B.V.

Evaluation of capillary zone electrophoresis for the quality control of complex biologic samples: Application to snake venoms.

PubMed

Kpaibe, André P S; Ben-Ameur, Randa; Coussot, Gaëlle; Ladner, Yoann; Montels, Jérôme; Ake, Michèle; Perrin, Catherine

2017-08-01

Snake venoms constitute a very promising resource for the development of new medicines. They are mainly composed of very complex peptide and protein mixtures, which composition may vary significantly from batch to batch. This latter consideration is a challenge for routine quality control (QC) in the pharmaceutical industry. In this paper, we report the use of capillary zone electrophoresis for the development of an analytical fingerprint methodology to assess the quality of snake venoms. The analytical fingerprint concept is being widely used for the QC of herbal drugs but rarely for venoms QC so far. CZE was chosen for its intrinsic efficiency in the separation of protein and peptide mixtures. The analytical fingerprint methodology was first developed and evaluated for a particular snake venom, Lachesis muta. Optimal analysis conditions required the use of PDADMAC capillary coating to avoid protein and peptide adsorption. Same analytical conditions were then applied to other snake venom species. Different electrophoretic profiles were obtained for each venom. Excellent repeatability and intermediate precision was observed for each batch. Analysis of different batches of the same species revealed inherent qualitative and quantitative composition variations of the venoms between individuals. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2017 Workplace and Gender Relations Survey of Reserve Component Members: Statistical Methodology Report

DTIC Science & Technology

2018-04-30

2017 Workplace and Gender Relations Survey of Reserve Component Members Statistical Methodology Report Additional copies of this report...Survey of Reserve Component Members Statistical Methodology Report Office of People Analytics (OPA) 4800 Mark Center Drive, Suite...RESERVE COMPONENT MEMBERS STATISTICAL METHODOLOGY REPORT Introduction The Office of People Analytics’ Center for Health and Resilience (OPA[H&R

Size analysis of polyglutamine protein aggregates using fluorescence detection in an analytical ultracentrifuge.

PubMed

Polling, Saskia; Hatters, Danny M; Mok, Yee-Foong

2013-01-01

Defining the aggregation process of proteins formed by poly-amino acid repeats in cells remains a challenging task due to a lack of robust techniques for their isolation and quantitation. Sedimentation velocity methodology using fluorescence detected analytical ultracentrifugation is one approach that can offer significant insight into aggregation formation and kinetics. While this technique has traditionally been used with purified proteins, it is now possible for substantial information to be collected with studies using cell lysates expressing a GFP-tagged protein of interest. In this chapter, we describe protocols for sample preparation and setting up the fluorescence detection system in an analytical ultracentrifuge to perform sedimentation velocity experiments on cell lysates containing aggregates formed by poly-amino acid repeat proteins.

Analytical Chemistry Developmental Work Using a 243Am Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, Khalil J.; Stanley, Floyd E.; Porterfield, Donivan R.

2015-02-24

This project seeks to reestablish our analytical capability to characterize Am bulk material and develop a reference material suitable to characterizing the purity and assay of 241Am oxide for industrial use. The tasks associated with this phase of the project included conducting initial separations experiments, developing thermal ionization mass spectrometry capability using the 243Am isotope as an isotope dilution spike , optimizing the spike for the determination of 241Pu- 241 Am radiochemistry, and, additionally, developing and testing a methodology which can detect trace to ultra- trace levels of Pu (both assay and isotopics) in bulk Am samples .

Liquid chromatography-tandem mass spectrometry analysis of perfluorooctane sulfonate and perfluorooctanoic Acid in fish fillet samples.

PubMed

Paiano, Viviana; Fattore, Elena; Carrà, Andrea; Generoso, Caterina; Fanelli, Roberto; Bagnati, Renzo

2012-01-01

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic (PFOA) acid are persistent contaminants which can be found in environmental and biological samples. A new and fast analytical method is described here for the analysis of these compounds in the edible part of fish samples. The method uses a simple liquid extraction by sonication, followed by a direct determination using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The linearity of the instrumental response was good, with average regression coefficients of 0.9971 and 0.9979 for PFOS and PFOA, respectively, and the coefficients of variation (CV) of the method ranged from 8% to 20%. Limits of detection (LOD) were 0.04 ng/g for both the analytes and recoveries were 90% for PFOS and 76% for PFOA. The method was applied to samples of homogenized fillets of wild and farmed fish from the Mediterranean Sea. Most of the samples showed little or no contamination by perfluorooctane sulfonate and perfluorooctanoic acid, and the highest concentrations detected among the fish species analyzed were, respectively, 5.96 ng/g and 1.89 ng/g. The developed analytical methodology can be used as a tool to monitor and to assess human exposure to perfluorinated compounds through sea food consumption.

Plasma creatinine in dogs: intra- and inter-laboratory variation in 10 European veterinary laboratories

PubMed Central

2011-01-01

Background There is substantial variation in reported reference intervals for canine plasma creatinine among veterinary laboratories, thereby influencing the clinical assessment of analytical results. The aims of the study was to determine the inter- and intra-laboratory variation in plasma creatinine among 10 veterinary laboratories, and to compare results from each laboratory with the upper limit of its reference interval. Methods Samples were collected from 10 healthy dogs, 10 dogs with expected intermediate plasma creatinine concentrations, and 10 dogs with azotemia. Overlap was observed for the first two groups. The 30 samples were divided into 3 batches and shipped in random order by postal delivery for plasma creatinine determination. Statistical testing was performed in accordance with ISO standard methodology. Results Inter- and intra-laboratory variation was clinically acceptable as plasma creatinine values for most samples were usually of the same magnitude. A few extreme outliers caused three laboratories to fail statistical testing for consistency. Laboratory sample means above or below the overall sample mean, did not unequivocally reflect high or low reference intervals in that laboratory. Conclusions In spite of close analytical results, further standardization among laboratories is warranted. The discrepant reference intervals seem to largely reflect different populations used in establishing the reference intervals, rather than analytical variation due to different laboratory methods. PMID:21477356

Rapid methodology via mass spectrometry to quantify addition of soybean oil in extra virgin olive oil: A comparison with traditional methods adopted by food industry to identify fraud.

PubMed

da Silveira, Roberta; Vágula, Julianna Matias; de Lima Figueiredo, Ingrid; Claus, Thiago; Galuch, Marilia Bellanda; Santos Junior, Oscar Oliveira; Visentainer, Jesui Vergilio

2017-12-01

Fast and innovative methodology to monitors the addition of soybean oil in extra virgin olive oil was developed employing ESI-MS with ionization operating in positive mode. A certified extra virgin olive oil and refined soybean oil samples were analyzed by direct infusion, the identification of a natural lipid marker present only in soybean oil (m/z 886.68 [TAG+NH 4 ] + ) was possible. The certified extra virgin olive oil was purposely adulterated with soybean oil in different levels (1, 5, 10, 20, 50, 70, 90%) being possible to observe that the new methodology is able to detect even small fraud concentration, such as 1% (v/v). Additionally, commercial samples were analyzed and were observed the addition of soybean oil as a common fraud in this segment. This powerful analytical method proposed could be applied as routine analysis by control organization, as well as food industries, considering its pronounced advantages; simplicity, rapidity, elevated detectability and minor amounts of sample and solvent consumed. Copyright © 2017 Elsevier Ltd. All rights reserved.

An improved approach for flight readiness certification: Probabilistic models for flaw propagation and turbine blade failure. Volume 1: Methodology and applications

NASA Technical Reports Server (NTRS)

Moore, N. R.; Ebbeler, D. H.; Newlin, L. E.; Sutharshana, S.; Creager, M.

1992-01-01

An improved methodology for quantitatively evaluating failure risk of spaceflight systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with analytical modeling of failure phenomena to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in analytical modeling, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which analytical models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. State-of-the-art analytical models currently employed for designs failure prediction, or performance analysis are used in this methodology. The rationale for the statistical approach taken in the PFA methodology is discussed, the PFA methodology is described, and examples of its application to structural failure modes are presented. The engineering models and computer software used in fatigue crack growth and fatigue crack initiation applications are thoroughly documented.

Multi-analyte method development for analysis of brominated flame retardants (BFRs) and PBDE metabolites in human serum.

PubMed

Lu, Dasheng; Jin, Yu'e; Feng, Chao; Wang, Dongli; Lin, Yuanjie; Qiu, Xinlei; Xu, Qian; Wen, Yimin; She, Jianwen; Wang, Guoquan; Zhou, Zhijun

2017-09-01

Commonly, analytical methods measuring brominated flame retardants (BFRs) of different chemical polarities in human serum are labor consuming and tedious. Our study used acidified diatomaceous earth as solid-phase extraction (SPE) adsorbent and defatting material to simultaneously determine the most abundant BFRs and their metabolites with different polarities in human serum samples. The analytes include three types of commercial BFRs, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) isomers, and polybrominated biphenyl ethers (PBDEs), and dominant hydroxylated BDE (OH-PBDE) and methoxylated BDE (MeO-PBDE) metabolites of PBDEs. The sample eluents were sequentially analyzed for PBDEs and MeO-BDEs on online gel permeation chromatography/gas chromatography-electron capture-negative ionization mass spectrometry (online GPC GC-ECNI-MS) and for TBBPA, HBCD, and OH-BDEs on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Method recoveries were 67-134% with a relative standard deviation (RSD) of less than 20%. Method detection limits (MDLs) were 0.30-4.20 pg/mL fresh weight (f.w.) for all analytes, except for BDE-209 of 16 pg/mL f.w. The methodology was also applied in a pilot study, which analyzed ten real samples from healthy donors in China, and the majority of target analytes were detected with a detection rate of more than 80%. To our knowledge, it is the first time for us in effectively determining BFRs of most types in one aliquot of human serum samples. This new analytical method is more specific, sensitive, accurate, and time saving for routine biomonitoring of these BFRs and for integrated assessment of health risk of BFR exposure.

Fast, sensitive and reliable multi-residue method for routine determination of 34 pesticides from various chemical groups in water samples by using dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry.

PubMed

Tankiewicz, Maciej; Biziuk, Marek

2018-02-01

A simple and efficient dispersive liquid-liquid microextraction technique (DLLME) was developed by using a mixture of two solvents: 40 μL of tetrachlorethylene (extraction solvent) and 1.0 mL of methanol (disperser solvent), which was rapidly injected with a syringe into 10 mL of water sample. Some important parameters affecting the extraction efficiency, such as type and volume of solvents, water sample volume, extraction time, temperature, pH adjustment and salt addition effect were investigated. Simultaneous determination of 34 commonly used pesticides was performed by using gas chromatography coupled with mass spectrometry (GC-MS). The procedure has been validated in order to obtain the highest efficiency at the lowest concentration levels of analytes to fulfill the requirements of regulations on maximum residue limits. Under the optimum conditions, the linearity range was within 0.0096-100 μg L -1 . The limits of detection (LODs) of the developed DLLME-GC-MS methodology for all investigated pesticides were in the range of 0.0032 (endrin)-0.0174 (diazinon) μg L -1 and limits of quantification (LOQs) from 0.0096 to 0.052 μg L -1 . At lower concentration of 1 μg L -1 for each pesticide, recoveries ranged between 84% (tebufenpyrad) and 108% (deltamethrin) with relative standard deviations (RSDs) (n = 7) from 1.1% (metconazole) to 11% (parathion-mehtyl). This methodology was successfully applied to check contamination of environmental samples. The procedure has proved to be selective, sensitive and precise for the simultaneous determination of various pesticides. The optimized analytical method is very simple and rapid (less than 5 min). Graphical abstract Analytical procedure for testing water samples consists of dispersive liquid-liquid microextraction (DLLME) and gas chromatography coupled with mass spectrometry (GC-MS).

Forensic Investigation of Formaldehyde in Illicit Products for Hair Treatment by DAD-HPLC: A Case Study.

PubMed

Oiye, Erica N; Ribeiro, Maria Fernanda M; Okumura, Leonardo L; Saczk, Adelir A; Ciancaglini, Pietro; de Oliveira, Marcelo F

2016-07-01

The illegal use of formalin (commercial formaldehyde) in cosmetic products harms the health of individuals exposed to this substance. Over the last years, the commercial availability of these products, especially those containing irregular dosage of formaldehyde, has increased in Brazil. This work analyzes some products for hair treatment available in the Brazilian market and verifies their safety. The adopted analytical methodology involved sample derivatization with 2,4-dinitrophenylhydrazine, followed by high-performance liquid chromatography with ultraviolet detection (UV-VIS) at λ = 365 nm. The limit of quantification is 2.5 × 10 -3% w/w, and the recovery tests were around 93%. Some of the samples contained high and illegal formaldehyde levels ranging from 9% to 19% (w/w) and others presented suitable concentrations of the analyte. On the basis of the results, this work discusses the efficiency and practicality of this analytical method for forensic purposes. © 2016 American Academy of Forensic Sciences.

A framework for inference about carnivore density from unstructured spatial sampling of scat using detector dogs

Treesearch

Craig M. Thompson; J. Andrew Royle; James D. Garner

2012-01-01

Wildlife management often hinges upon an accurate assessment of population density. Although undeniably useful, many of the traditional approaches to density estimation such as visual counts, livetrapping, or mark–recapture suffer from a suite of methodological and analytical weaknesses. Rare, secretive, or highly mobile species exacerbate these problems through the...

Emerging Demands for Public Policies in Rio De Janeiro: Educational Prevention of Social Risks

ERIC Educational Resources Information Center

Gomes Da Silva, Magda Maria Ventura; Garcia, Maria del Pilar Quicios

2016-01-01

This paper disseminates some results of an international research on the social risk manifestations published in eight periodicals in Rio de Janeiro from July 2013 to December 2014. A sample of the research coincides with the population: 541 news, which constitutes 1255 analytical units. The methodology consisted of a content analysis of the news,…

Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium.

PubMed

Boiano, J M; Wallace, M E; Sieber, W K; Groff, J H; Wang, J; Ashley, K

2000-08-01

A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between results obtained from performance evaluation samples for the NIOSH field method and the OSHA laboratory method.

A Systematic Review of Published Respondent-Driven Sampling Surveys Collecting Behavioral and Biologic Data.

PubMed

Johnston, Lisa G; Hakim, Avi J; Dittrich, Samantha; Burnett, Janet; Kim, Evelyn; White, Richard G

2016-08-01

Reporting key details of respondent-driven sampling (RDS) survey implementation and analysis is essential for assessing the quality of RDS surveys. RDS is both a recruitment and analytic method and, as such, it is important to adequately describe both aspects in publications. We extracted data from peer-reviewed literature published through September, 2013 that reported collected biological specimens using RDS. We identified 151 eligible peer-reviewed articles describing 222 surveys conducted in seven regions throughout the world. Most published surveys reported basic implementation information such as survey city, country, year, population sampled, interview method, and final sample size. However, many surveys did not report essential methodological and analytical information for assessing RDS survey quality, including number of recruitment sites, seeds at start and end, maximum number of waves, and whether data were adjusted for network size. Understanding the quality of data collection and analysis in RDS is useful for effectively planning public health service delivery and funding priorities.

Plant gum identification in historic artworks

PubMed Central

Granzotto, Clara; Arslanoglu, Julie; Rolando, Christian; Tokarski, Caroline

2017-01-01

We describe an integrated and straightforward new analytical protocol that identifies plant gums from various sample sources including cultural heritage. Our approach is based on the identification of saccharidic fingerprints using mass spectrometry following controlled enzymatic hydrolysis. We developed an enzyme cocktail suitable for plant gums of unknown composition. Distinctive MS profiles of gums such as arabic, cherry and locust-bean gums were successfully identified. A wide range of oligosaccharidic combinations of pentose, hexose, deoxyhexose and hexuronic acid were accurately identified in gum arabic whereas cherry and locust bean gums showed respectively PentxHexy and Hexn profiles. Optimized for low sample quantities, the analytical protocol was successfully applied to contemporary and historic samples including ‘Colour Box Charles Roberson & Co’ dating 1870s and drawings from the American painter Arthur Dove (1880–1946). This is the first time that a gum is accurately identified in a cultural heritage sample using structural information. Furthermore, this methodology is applicable to other domains (food, cosmetic, pharmaceutical, biomedical). PMID:28425501

Determination of artificial sweeteners in beverages with green mobile phases and high temperature liquid chromatography-tandem mass spectrometry.

PubMed

Ordoñez, Edgar Y; Rodil, Rosario; Quintana, José Benito; Cela, Rafael

2015-02-15

A new analytical procedure involving the use of water and a low percentage of ethanol combined to high temperature liquid chromatography-tandem mass spectrometry has been developed for the determination of nine high-intensity sweeteners in a variety of drink samples. The method permitted the analysis in 23min (including column reequilibration) and consuming only 0.85mL of a green organic solvent (ethanol). This methodology provided limits of detection (after 50-fold dilution) in the 0.05-10mg/L range, with recoveries (obtained from five different types of beverages) being in the 86-110% range and relative standard deviation values lower than 12%. Finally, the method was applied to 25 different samples purchased in Spain, where acesulfame and sucralose were the most frequently detected analytes (>50% of the samples) and cyclamate was found over the legislation limit set by the European Union in a sample and at the regulation boundary in three others. Copyright © 2014 Elsevier Ltd. All rights reserved.

Estimation of the diagnostic threshold accounting for decision costs and sampling uncertainty.

PubMed

Skaltsa, Konstantina; Jover, Lluís; Carrasco, Josep Lluís

2010-10-01

Medical diagnostic tests are used to classify subjects as non-diseased or diseased. The classification rule usually consists of classifying subjects using the values of a continuous marker that is dichotomised by means of a threshold. Here, the optimum threshold estimate is found by minimising a cost function that accounts for both decision costs and sampling uncertainty. The cost function is optimised either analytically in a normal distribution setting or empirically in a free-distribution setting when the underlying probability distributions of diseased and non-diseased subjects are unknown. Inference of the threshold estimates is based on approximate analytically standard errors and bootstrap-based approaches. The performance of the proposed methodology is assessed by means of a simulation study, and the sample size required for a given confidence interval precision and sample size ratio is also calculated. Finally, a case example based on previously published data concerning the diagnosis of Alzheimer's patients is provided in order to illustrate the procedure.

Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis.

PubMed

Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel

2017-10-20

The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m 3 ) and benzene (1.7±0.5μg/m 3 ) is lower when using TGDE compared to methanol, which was previously used (385μg/m 3 for TCE and 130μg/m 3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ 13 C analysis. Due to a different analytical procedure, the method detection limit associated with δ 37 Cl analysis was found to be 156±6μg/m 3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling method without the need to determine the initial gas phase TCE concentration. The simplified field deployment approach of the solvent-based dissolution method combined with the conventional analytical procedure used for groundwater samples substantially facilitates the application of CSIA to gas phase studies. Copyright © 2017 Elsevier B.V. All rights reserved.

How Big of a Problem is Analytic Error in Secondary Analyses of Survey Data?

PubMed

West, Brady T; Sakshaug, Joseph W; Aurelien, Guy Alain S

2016-01-01

Secondary analyses of survey data collected from large probability samples of persons or establishments further scientific progress in many fields. The complex design features of these samples improve data collection efficiency, but also require analysts to account for these features when conducting analysis. Unfortunately, many secondary analysts from fields outside of statistics, biostatistics, and survey methodology do not have adequate training in this area, and as a result may apply incorrect statistical methods when analyzing these survey data sets. This in turn could lead to the publication of incorrect inferences based on the survey data that effectively negate the resources dedicated to these surveys. In this article, we build on the results of a preliminary meta-analysis of 100 peer-reviewed journal articles presenting analyses of data from a variety of national health surveys, which suggested that analytic errors may be extremely prevalent in these types of investigations. We first perform a meta-analysis of a stratified random sample of 145 additional research products analyzing survey data from the Scientists and Engineers Statistical Data System (SESTAT), which describes features of the U.S. Science and Engineering workforce, and examine trends in the prevalence of analytic error across the decades used to stratify the sample. We once again find that analytic errors appear to be quite prevalent in these studies. Next, we present several example analyses of real SESTAT data, and demonstrate that a failure to perform these analyses correctly can result in substantially biased estimates with standard errors that do not adequately reflect complex sample design features. Collectively, the results of this investigation suggest that reviewers of this type of research need to pay much closer attention to the analytic methods employed by researchers attempting to publish or present secondary analyses of survey data.

How Big of a Problem is Analytic Error in Secondary Analyses of Survey Data?

PubMed Central

West, Brady T.; Sakshaug, Joseph W.; Aurelien, Guy Alain S.

2016-01-01

Secondary analyses of survey data collected from large probability samples of persons or establishments further scientific progress in many fields. The complex design features of these samples improve data collection efficiency, but also require analysts to account for these features when conducting analysis. Unfortunately, many secondary analysts from fields outside of statistics, biostatistics, and survey methodology do not have adequate training in this area, and as a result may apply incorrect statistical methods when analyzing these survey data sets. This in turn could lead to the publication of incorrect inferences based on the survey data that effectively negate the resources dedicated to these surveys. In this article, we build on the results of a preliminary meta-analysis of 100 peer-reviewed journal articles presenting analyses of data from a variety of national health surveys, which suggested that analytic errors may be extremely prevalent in these types of investigations. We first perform a meta-analysis of a stratified random sample of 145 additional research products analyzing survey data from the Scientists and Engineers Statistical Data System (SESTAT), which describes features of the U.S. Science and Engineering workforce, and examine trends in the prevalence of analytic error across the decades used to stratify the sample. We once again find that analytic errors appear to be quite prevalent in these studies. Next, we present several example analyses of real SESTAT data, and demonstrate that a failure to perform these analyses correctly can result in substantially biased estimates with standard errors that do not adequately reflect complex sample design features. Collectively, the results of this investigation suggest that reviewers of this type of research need to pay much closer attention to the analytic methods employed by researchers attempting to publish or present secondary analyses of survey data. PMID:27355817

Educational Design as Conversation: A Conversation Analytical Perspective on Teacher Dialogue

ERIC Educational Resources Information Center

van Kruiningen, Jacqueline F.

2013-01-01

The aim of this methodological paper is to expound on and demonstrate the value of conversation-analytical research in the area of (informal) teacher learning. The author discusses some methodological issues in current research on interaction in teacher learning and holds a plea for conversation-analytical research on interactional processes in…

Conventional and Accelerated-Solvent Extractions of Green Tea (Camellia sinensis) for Metabolomics-based Chemometrics

PubMed Central

Kellogg, Joshua J.; Wallace, Emily D.; Graf, Tyler N.; Oberlies, Nicholas H.; Cech, Nadja B.

2018-01-01

Metabolomics has emerged as an important analytical technique for multiple applications. The value of information obtained from metabolomics analysis depends on the degree to which the entire metabolome is present and the reliability of sample treatment to ensure reproducibility across the study. The purpose of this study was to compare methods of preparing complex botanical extract samples prior to metabolomics profiling. Two extraction methodologies, accelerated solvent extraction and a conventional solvent maceration, were compared using commercial green tea [Camellia sinensis (L.) Kuntze (Theaceae)] products as a test case. The accelerated solvent protocol was first evaluated to ascertain critical factors influencing extraction using a D-optimal experimental design study. The accelerated solvent and conventional extraction methods yielded similar metabolite profiles for the green tea samples studied. The accelerated solvent extraction yielded higher total amounts of extracted catechins, was more reproducible, and required less active bench time to prepare the samples. This study demonstrates the effectiveness of accelerated solvent as an efficient methodology for metabolomics studies. PMID:28787673

An improved approach for flight readiness certification: Probabilistic models for flaw propagation and turbine blade failure. Volume 2: Software documentation

NASA Technical Reports Server (NTRS)

Moore, N. R.; Ebbeler, D. H.; Newlin, L. E.; Sutharshana, S.; Creager, M.

1992-01-01

An improved methodology for quantitatively evaluating failure risk of spaceflights systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with analytical modeling of failure phenomena to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in analytical modeling, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which analytical models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. State-of-the-art analytical models currently employed for design, failure prediction, or performance analysis are used in this methodology. The rationale for the statistical approach taken in the PFA methodology is discussed, the PFA methodology is described, and examples of its application to structural failure modes are presented. The engineering models and computer software used in fatigue crack growth and fatigue crack initiation applications are thoroughly documented.

Determination of the herbicide benfuresate by its photo-induced chemiluminescence using flow multicommutation methodology.

PubMed

Albert-García, J R; Calatayud, J Martínez

2008-05-15

The present paper deals with an analytical strategy based on coupling photo-induced chemiluminescence in a multicommutation continuous-flow methodology for the determination of the herbicide benfuresate. The solenoid valve inserted as small segments of the analyte solution was sequentially alternated with segments of the NaOH solution for adjusting the medium for the photodegradation. Both flow rates (sample and medium) were adjusted to required time for photodegradation, 90 s; and then, the resulting solution was also sequentially inserted as segments alternated with segments of the oxidizing solution system, hexacyanoferrate (III) in alkaline medium. The calibration range from 1 microg L(-1) to 95 mg L(-1), resulted in a linear behaviour over the range 1 microg L(-1) to 4 mg L(-1) and fitting the linear equation: I=4555.7x+284.2, correlation coefficient 0.9999. The limit of detection was 0.1 microg L(-1) (n=5, criteria 3 sigma) and the sample throughput was 22 h(-1). The consumption of solutions was very small; per peak were 0.66 mL, 0.16 mL and 0. 32 mL sample, medium and oxidant, respectively. Inter- and intra-day reproducibility resulted in a R.S.D. of 3.9% and 3.4%, respectively. After testing the influence of a large series of potential interferents the method is applied to water samples obtained from different places, human urine and to one formulation.

A simple and highly selective molecular imprinting polymer-based methodology for propylparaben monitoring in personal care products and industrial waste waters.

PubMed

Vicario, Ana; Aragón, Leslie; Wang, Chien C; Bertolino, Franco; Gomez, María R

2018-02-05

In this work, a novel molecularly imprinted polymer (MIP) proposed as solid phase extraction sorbent was developed for the determination of propylparaben (PP) in diverse cosmetic samples. The use of parabens (PAs) is authorized by regulatory agencies as microbiological preservative; however, recently several studies claim that large-scale use of these preservatives can be a potential health risk and harmful to the environment. Diverse factors that influence on polymer synthesis were studied, including template, functional monomer, porogen and crosslinker used. Morphological characterization of the MIP was performed using SEM and BET analysis. Parameters affecting the molecularly imprinted solid phase extraction (MISPE) and elution efficiency of PP were evaluated. After sample clean-up, the analyte was analyzed by high performance liquid chromatography (HPLC). The whole procedure was validated, showing satisfactory analytical parameters. After applying the MISPE methodology, the extraction recoveries were always better than 86.15%; the obtained precision expressed as RSD% was always lower than 2.19 for the corrected peak areas. Good linear relationship was obtained within the range 8-500ngmL -1 of PP, r 2 =0.99985. Lower limits of detection and quantification after MISPE procedure of 2.4 and 8ngmL -1 , respectively were reached, in comparison with previously reported methodologies. The development of MISPE-HPLC methodology provided a simple an economic way for accomplishing a clean-up/preconcentration step and the subsequent determination of PP in a complex matrix. The performance of the proposed method was compared against C-18 and silica solid phase extraction (SPE) cartridges. The recovery factors obtained after applying extraction methods were 96.6, 64.8 and 0.79 for MISPE, C18-SPE and silica-SPE procedures, respectively. The proposed methodology improves the retention capability of SPE material plus robustness and possibility of reutilization, enabling it to be used for PP routine monitoring in diverse personal care products (PCP) and environmental samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Green aspects, developments and perspectives of liquid phase microextraction techniques.

PubMed

Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek

2014-02-01

Determination of analytes at trace levels in complex samples (e.g. biological or contaminated water or soils) are often required for the environmental assessment and monitoring as well as for scientific research in the field of environmental pollution. A limited number of analytical techniques are sensitive enough for the direct determination of trace components in samples and, because of that, a preliminary step of the analyte isolation/enrichment prior to analysis is required in many cases. In this work the newest trends and innovations in liquid phase microextraction, like: single-drop microextraction (SDME), hollow fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) have been discussed, including their critical evaluation and possible application in analytical practice. The described modifications of extraction techniques deal with system miniaturization and/or automation, the use of ultrasound and physical agitation, and electrochemical methods. Particular attention was given to pro-ecological aspects therefore the possible use of novel, non-toxic extracting agents, inter alia, ionic liquids, coacervates, surfactant solutions and reverse micelles in the liquid phase microextraction techniques has been evaluated in depth. Also, new methodological solutions and the related instruments and devices for the efficient liquid phase micoextraction of analytes, which have found application at the stage of procedure prior to chromatographic determination, are presented. © 2013 Published by Elsevier B.V.

Rapid ultra-trace analysis of sucralose in multiple-origin aqueous samples by online solid-phase extraction coupled to high-resolution mass spectrometry.

PubMed

Batchu, Sudha Rani; Ramirez, Cesar E; Gardinali, Piero R

2015-05-01

Because of its widespread consumption and its persistence during wastewater treatment, the artificial sweetener sucralose has gained considerable interest as a proxy to detect wastewater intrusion into usable water resources. The molecular resilience of this compound dictates that coastal and oceanic waters are the final recipient of this compound with unknown effects on ecosystems. Furthermore, no suitable methodologies have been reported for routine, ultra-trace detection of sucralose in seawater as the sensitivity of traditional liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis is limited by a low yield of product ions upon collision-induced dissociation (CID). In this work, we report the development and field test of an alternative analysis tool for sucralose in environmental waters, with enough sensitivity for the proper quantitation and confirmation of this analyte in seawater. The methodology is based on automated online solid-phase extraction (SPE) and high-resolving-power orbitrap MS detection. Operating in full scan (no CID), detection of the unique isotopic pattern (100:96:31 for [M-H](-), [M-H+2](-), and [M-H+4](-), respectively) was used for ultra-trace quantitation and analyte identification. The method offers fast analysis (14 min per run) and low sample consumption (10 mL per sample) with method detection and confirmation limits (MDLs and MCLs) of 1.4 and 5.7 ng/L in seawater, respectively. The methodology involves low operating costs due to virtually no sample preparation steps or consumables. As an application example, samples were collected from 17 oceanic and estuarine sites in Broward County, FL, with varying salinity (6-40 PSU). Samples included the ocean outfall of the Southern Regional Wastewater Treatment Plant (WWTP) that serves Hollywood, FL. Sucralose was detected above MCL in 78% of the samples at concentrations ranging from 8 to 148 ng/L, with the exception of the WWTP ocean outfall (at pipe end, 28 m below the surface) where the measured concentration was 8418 ± 3813 ng/L. These results demonstrate the applicability of this monitoring tool for the trace-level detection of this wastewater marker in very dilute environmental waters.

MS-Based Analytical Techniques: Advances in Spray-Based Methods and EI-LC-MS Applications

PubMed Central

Medina, Isabel; Cappiello, Achille; Careri, Maria

2018-01-01

Mass spectrometry is the most powerful technique for the detection and identification of organic compounds. It can provide molecular weight information and a wealth of structural details that give a unique fingerprint for each analyte. Due to these characteristics, mass spectrometry-based analytical methods are showing an increasing interest in the scientific community, especially in food safety, environmental, and forensic investigation areas where the simultaneous detection of targeted and nontargeted compounds represents a key factor. In addition, safety risks can be identified at the early stage through online and real-time analytical methodologies. In this context, several efforts have been made to achieve analytical instrumentation able to perform real-time analysis in the native environment of samples and to generate highly informative spectra. This review article provides a survey of some instrumental innovations and their applications with particular attention to spray-based MS methods and food analysis issues. The survey will attempt to cover the state of the art from 2012 up to 2017. PMID:29850370

Long-term urine biobanking: storage stability of clinical chemical parameters under moderate freezing conditions without use of preservatives.

PubMed

Remer, Thomas; Montenegro-Bethancourt, Gabriela; Shi, Lijie

2014-12-01

To examine the long-term stability and validity of analyte concentrations of 21 clinical biochemistry parameters in 24-h urine samples stored for 12 or 15 yr at -22°C and preservative free. Healthy children's 24-h urine samples in which the respective analytes had been measured shortly after sample collection (baseline) were reanalyzed. Second measurement was performed after 12 yr (organic acids) and 15 yr (creatinine, urea, osmolality, iodine, nitrogen, anions, cations, acid-base parameters) with the same analytical methodology. Paired comparisons and correlations between the baseline and repeated measurements were done. Recovery rates were calculated. More than half of the analytes (creatinine, urea, iodine, nitrogen, sodium, potassium, magnesium, calcium, ammonium, bicarbonate, citric & uric acid) showed measurement values after >10 yr of storage not significantly different from baseline. 15 of the 21 parameters were highly correlated (r=0.99) between baseline and second measurement. Poorest correlation was r=0.77 for oxalate. Recovery ranged from 73% (oxalate) to 105% (phosphate). Our results suggest high long-term stability and measurement validity for numerous clinical chemistry parameters stored at -22°C without addition of any urine preservative. Prospective storage of urine aliquots at -22°C for periods even exceeding 10 yr, appears to be an acceptable and valid tool in epidemiological settings for later quantification of several urine analytes. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Quantification of endocrine disruptors and pesticides in water by gas chromatography-tandem mass spectrometry. Method validation using weighted linear regression schemes.

PubMed

Mansilha, C; Melo, A; Rebelo, H; Ferreira, I M P L V O; Pinho, O; Domingues, V; Pinho, C; Gameiro, P

2010-10-22

A multi-residue methodology based on a solid phase extraction followed by gas chromatography-tandem mass spectrometry was developed for trace analysis of 32 compounds in water matrices, including estrogens and several pesticides from different chemical families, some of them with endocrine disrupting properties. Matrix standard calibration solutions were prepared by adding known amounts of the analytes to a residue-free sample to compensate matrix-induced chromatographic response enhancement observed for certain pesticides. Validation was done mainly according to the International Conference on Harmonisation recommendations, as well as some European and American validation guidelines with specifications for pesticides analysis and/or GC-MS methodology. As the assumption of homoscedasticity was not met for analytical data, weighted least squares linear regression procedure was applied as a simple and effective way to counteract the greater influence of the greater concentrations on the fitted regression line, improving accuracy at the lower end of the calibration curve. The method was considered validated for 31 compounds after consistent evaluation of the key analytical parameters: specificity, linearity, limit of detection and quantification, range, precision, accuracy, extraction efficiency, stability and robustness. Copyright © 2010 Elsevier B.V. All rights reserved.

Subthreshold posttraumatic stress disorder: A meta-analytic review of DSM-IV prevalence and a proposed DSM-5 approach to measurement.

PubMed

Brancu, Mira; Mann-Wrobel, Monica; Beckham, Jean C; Wagner, H Ryan; Elliott, Alyssa; Robbins, Allison T; Wong, Madrianne; Berchuck, Ania E; Runnals, Jennifer J

2016-03-01

Subthreshold posttraumatic stress disorder (PTSD) is a chronic condition that is often ignored, the cumulative effects of which can negatively impact an individual's quality of life and overall health care costs. However, subthreshold PTSD prevalence rates and impairment remain unclear due to variations in research methodology. This study examined the existing literature in order to recommend approaches to standardize subthreshold PTSD assessment. We conducted (a) a meta-analysis of subthreshold PTSD prevalence rates and (b) compared functional impairment associated with the 3 most commonly studied subthreshold PTSD definitions. Meta-analytic results revealed that the average prevalence rate of subthreshold PTSD across studies was 14.7%, with a lower rate (12.6%) among the most methodologically rigorous studies and higher rate (15.6%) across less rigorous studies. There were significant methodological differences among reviewed studies with regard to definition, measurement, and population. Different definitions led to prevalence rates ranging between 13.7% and 16.4%. Variability in prevalence rates most related to population and sample composition, with trauma type and community (vs. epidemiological) samples significantly impacting heterogeneity. Qualitative information gathered from studies presenting functional correlates supported current evidence that psychological and behavioral parameters were worse among subthreshold PTSD groups compared with no-PTSD groups, but not as severe as impairment in PTSD groups. Several studies also reported significant increased risk of suicidality and hopelessness as well as higher health care utilization rates among those with subthreshold PTSD (compared with trauma exposed no-PTSD samples). Based on findings, we propose recommendations for developing a standard approach to evaluation of subthreshold PTSD. (c) 2016 APA, all rights reserved).

Miniaturized QuEChERS based methodology for multiresidue determination of pesticides in odonate nymphs as ecosystem biomonitors.

PubMed

Jesús, Florencia; Hladki, Ricardo; Gérez, Natalia; Besil, Natalia; Niell, Silvina; Fernández, Grisel; Heinzen, Horacio; Cesio, María Verónica

2018-02-01

The impacts of the modern, agrochemicals based agriculture that threatens the overall systems sustainability, need to be monitored and evaluated. Seeking for agroecosystems monitors, the present article focus in the occurrence and abundance of aquatic macroinvertebrates, that have been frequently used as bioindicators of water quality due to their relationship with land use. Some of these organisms are on the top of the food chain, where bioaccumulation and biomagnification processes can be observed, and they can turn into secondary pollution sources of systems and terrestrial organisms as well. Odonate nymphs, which belong to the functional group of predators, were selected for this study. A methodology to determine 73 pesticide residues in odonate nymphs by LC-MS/MS and GC-MS/MS was developed. A QuEChERS sample preparation strategy was adapted. As it is complex to obtain samples especially in disturbed ecosystems, the method was minimized to a sample size of 200mg of fresh nymphs. The method was validated and good recoveries (71-120%) with RSDs below 20% for the majority of the studied pesticides at least at two of the assayed levels 1, 10 and 50µgkg -1 were obtained. For 32 analytes the limit of quantitation was 1µgkg -1 and 10µgkg -1 for the others. The lineal range was observed between 1-100µgkg -1 in matrix-matched and solvent calibration curves for most of the assessed pesticides. LC-MS/MS matrix effects were evaluated, 40% of the analytes presented low or no signal suppression. Only flufenoxuron presented high matrix effects. The obtained methodology is adequate for pesticide multiresidue analysis in aquatic macroinvertebrates (odonates) aiming to contribute to the ecological state evaluation of freshwater ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous grouping and ranking with combination of SOM and TOPSIS for selection of preferable analytical procedure for furan determination in food.

PubMed

Jędrkiewicz, Renata; Tsakovski, Stefan; Lavenu, Aurore; Namieśnik, Jacek; Tobiszewski, Marek

2018-02-01

Novel methodology for grouping and ranking with application of self-organizing maps and multicriteria decision analysis is presented. The dataset consists of 22 objects that are analytical procedures applied to furan determination in food samples. They are described by 10 variables, referred to their analytical performance, environmental and economic aspects. Multivariate statistics analysis allows to limit the amount of input data for ranking analysis. Assessment results show that the most beneficial procedures are based on microextraction techniques with GC-MS final determination. It is presented how the information obtained from both tools complement each other. The applicability of combination of grouping and ranking is also discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholtz, Jean

A new field of research, visual analytics, has recently been introduced. This has been defined as “the science of analytical reasoning facilitated by visual interfaces." Visual analytic environments, therefore, support analytical reasoning using visual representations and interactions, with data representations and transformation capabilities, to support production, presentation and dissemination. As researchers begin to develop visual analytic environments, it will be advantageous to develop metrics and methodologies to help researchers measure the progress of their work and understand the impact their work will have on the users who will work in such environments. This paper presents five areas or aspects ofmore » visual analytic environments that should be considered as metrics and methodologies for evaluation are developed. Evaluation aspects need to include usability, but it is necessary to go beyond basic usability. The areas of situation awareness, collaboration, interaction, creativity, and utility are proposed as areas for initial consideration. The steps that need to be undertaken to develop systematic evaluation methodologies and metrics for visual analytic environments are outlined.« less

Evaluation and performance of desorption electrospray ionization using a triple quadrupole mass spectrometer for quantitation of pharmaceuticals in plasma.

PubMed

Kennedy, Joseph H; Wiseman, Justin M

2010-02-01

The present work describes the methodology and investigates the performance of desorption electrospray ionization (DESI) combined with a triple quadrupole mass spectrometer for the quantitation of small drug molecules in human plasma. Amoxepine, atenolol, carbamazepine, clozapine, prazosin, propranolol and verapamil were selected as target analytes while terfenadine was selected as the internal standard common to each of the analytes. Protein precipitation of human plasma using acetonitrile was utilized for all samples. Limits of detection were determined for all analytes in plasma and shown to be in the range 0.2-40 ng/mL. Quantitative analysis of amoxepine, prazosin and verapamil was performed over the range 20-7400 ng/mL and shown to be linear in all cases with R(2) >0.99. In most cases, the precision (relative standard deviation) and accuracy (relative error) of each method were less than or equal to 20%, respectively. The performance of the combined techniques made it possible to analyze each sample in 15 s illustrating DESI tandem mass spectrometry (MS/MS) as powerful tool for the quantitation of analytes in deproteinized human plasma. Copyright 2010 John Wiley & Sons, Ltd.

New robust bilinear least squares method for the analysis of spectral-pH matrix data.

PubMed

Goicoechea, Héctor C; Olivieri, Alejandro C

2005-07-01

A new second-order multivariate method has been developed for the analysis of spectral-pH matrix data, based on a bilinear least-squares (BLLS) model achieving the second-order advantage and handling multiple calibration standards. A simulated Monte Carlo study of synthetic absorbance-pH data allowed comparison of the newly proposed BLLS methodology with constrained parallel factor analysis (PARAFAC) and with the combination multivariate curve resolution-alternating least-squares (MCR-ALS) technique under different conditions of sample-to-sample pH mismatch and analyte-background ratio. The results indicate an improved prediction ability for the new method. Experimental data generated by measuring absorption spectra of several calibration standards of ascorbic acid and samples of orange juice were subjected to second-order calibration analysis with PARAFAC, MCR-ALS, and the new BLLS method. The results indicate that the latter method provides the best analytical results in regard to analyte recovery in samples of complex composition requiring strict adherence to the second-order advantage. Linear dependencies appear when multivariate data are produced by using the pH or a reaction time as one of the data dimensions, posing a challenge to classical multivariate calibration models. The presently discussed algorithm is useful for these latter systems.

Implementation of structural response sensitivity calculations in a large-scale finite-element analysis system

NASA Technical Reports Server (NTRS)

Giles, G. L.; Rogers, J. L., Jr.

1982-01-01

The methodology used to implement structural sensitivity calculations into a major, general-purpose finite-element analysis system (SPAR) is described. This implementation includes a generalized method for specifying element cross-sectional dimensions as design variables that can be used in analytically calculating derivatives of output quantities from static stress, vibration, and buckling analyses for both membrane and bending elements. Limited sample results for static displacements and stresses are presented to indicate the advantages of analytically calculating response derivatives compared to finite difference methods. Continuing developments to implement these procedures into an enhanced version of SPAR are also discussed.

[Enzymatic analysis of the quality of foodstuffs].

PubMed

Kolesnov, A Iu

1997-01-01

Enzymatic analysis is an independent and separate branch of enzymology and analytical chemistry. It has become one of the most important methodologies used in food analysis. Enzymatic analysis allows the quick, reliable determination of many food ingredients. Often these contents cannot be determined by conventional methods, or if methods are available, they are determined only with limited accuracy. Today, methods of enzymatic analysis are being increasingly used in the investigation of foodstuffs. Enzymatic measurement techniques are used in industry, scientific and food inspection laboratories for quality analysis. This article describes the requirements of an optimal analytical method: specificity, sample preparation, assay performance, precision, sensitivity, time requirement, analysis cost, safety of reagents.

Versatile electrophoresis-based self-test platform.

PubMed

Guijt, Rosanne M

2015-03-01

Lab on a Chip technology offers the possibility to extract chemical information from a complex sample in a simple, automated way without the need for a laboratory setting. In the health care sector, this chemical information could be used as a diagnostic tool for example to inform dosing. In this issue, the research underpinning a family of electrophoresis-based point-of-care devices for self-testing of ionic analytes in various sample matrices is described [Electrophoresis 2015, 36, 712-721.]. Hardware, software, and methodological chances made to improve the overall analytical performance in terms of accuracy, precision, detection limit, and reliability are discussed. In addition to the main focus of lithium monitoring, new applications including the use of the platform for veterinary purposes, sodium, and for creatinine measurements are included. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protocols for the analytical characterization of therapeutic monoclonal antibodies. II - Enzymatic and chemical sample preparation.

PubMed

Bobaly, Balazs; D'Atri, Valentina; Goyon, Alexandre; Colas, Olivier; Beck, Alain; Fekete, Szabolcs; Guillarme, Davy

2017-08-15

The analytical characterization of therapeutic monoclonal antibodies and related proteins usually incorporates various sample preparation methodologies. Indeed, quantitative and qualitative information can be enhanced by simplifying the sample, thanks to the removal of sources of heterogeneity (e.g. N-glycans) and/or by decreasing the molecular size of the tested protein by enzymatic or chemical fragmentation. These approaches make the sample more suitable for chromatographic and mass spectrometric analysis. Structural elucidation and quality control (QC) analysis of biopharmaceutics are usually performed at intact, subunit and peptide levels. In this paper, general sample preparation approaches used to attain peptide, subunit and glycan level analysis are overviewed. Protocols are described to perform tryptic proteolysis, IdeS and papain digestion, reduction as well as deglycosylation by PNGase F and EndoS2 enzymes. Both historical and modern sample preparation methods were compared and evaluated using rituximab and trastuzumab, two reference therapeutic mAb products approved by Food and Drug Administration (FDA) and European Medicines Agency (EMA). The described protocols may help analysts to develop sample preparation methods in the field of therapeutic protein analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a fast capillary electrophoresis method for determination of carbohydrates in honey samples.

PubMed

Rizelio, Viviane Maria; Tenfen, Laura; da Silveira, Roberta; Gonzaga, Luciano Valdemiro; Costa, Ana Carolina Oliveira; Fett, Roseane

2012-05-15

In this study, the determination of fructose, glucose and sucrose by capillary electrophoresis (CE) was investigated. The tendency of the analyte to undergo electromigration dispersion and the buffer capacity were evaluated using the Peakmaster(®) software and considered in the optimization of the background electrolyte, which was composed of 20 mmol L(-1) sorbic acid, 0.2 mmol L(-1) CTAB and 40 mmol L(-1) NaOH at pH 12.2. Under optimal CE conditions, the separation of the substances investigated was achieved in less than 2 min. The detection limits for the three analytes were in the range of 0.022 and 0.029 g L(-1) and precision measurements within 0.62-4.69% were achieved. The proposed methodology was applied in the quantitative analysis by direct injection of in honey samples to determine the main sugars presents. The samples were previously dissolved in deionized water and filtered with no other sample treatment. The mean values for fructose, glucose and sucrose were in the ranges of 33.65-45.46 g 100g(-1), 24.63-35.06 g 100g(-1) and <0.22-1.32 g 100g(-1), respectively. The good analytical performance of the method makes it suitable for implementation in food laboratories for the routine analysis of honey samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Applications of luminescent systems to infectious disease methodology

NASA Technical Reports Server (NTRS)

Picciolo, G. L.; Chappelle, E. W.; Deming, J. W.; Mcgarry, M. A.; Nibley, D. A.; Okrend, H.; Thomas, R. R.

1976-01-01

The characterization of a clinical sample by a simple, fast, accurate, automatable analytical measurement is important in the management of infectious disease. Luminescence assays offer methods rich with options for these measurements. The instrumentation is common to each assay, and the investment is reasonable. Three general procedures were developed to varying degrees of completeness which measure bacterial levels by measuring their ATP, FMN and iron porphyrins. Bacteriuria detection and antibiograms can be determined within half a day. The characterization of the sample for its soluble ATP, FMN or prophyrins was also performed.

New methodology for the analysis of volatile organic compounds (VOCs) in bioethanol by gas chromatography coupled to mass spectrometry

NASA Astrophysics Data System (ADS)

Campos, M. S. G.; Sarkis, J. E. S.

2018-03-01

The present study presents a new analytical methodology for the determination of 11 compounds present in ethanol samples through the gas chromatography coupled to mass spectrometry (GC-MS) technique using a medium polarity chromatography column composed of 6% cyanopropyl-phenyl and 94% dimethyl polysiloxane. The validation parameters were determined according to NBR ISO 17025:2005. The recovery rates of the studied compounds were 100.4% to 114.7%. The limits of quantification are between 2.4 mg.kg-1 and 5.8 mg.kg-1. The uncertainty of the measurement was estimate in circa of 8%.

Integrated fiducial sample mount and software for correlated microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timothy R McJunkin; Jill R. Scott; Tammy L. Trowbridge

2014-02-01

A novel design sample mount with integrated fiducials and software for assisting operators in easily and efficiently locating points of interest established in previous analytical sessions is described. The sample holder and software were evaluated with experiments to demonstrate the utility and ease of finding the same points of interest in two different microscopy instruments. Also, numerical analysis of expected errors in determining the same position with errors unbiased by a human operator was performed. Based on the results, issues related to acquiring reproducibility and best practices for using the sample mount and software were identified. Overall, the sample mountmore » methodology allows data to be efficiently and easily collected on different instruments for the same sample location.« less

Analytical Utility of Campylobacter Methodologies

USDA-ARS?s Scientific Manuscript database

The National Advisory Committee on Microbiological Criteria for Foods (NACMCF, or the Committee) was asked to address the analytical utility of Campylobacter methodologies in preparation for an upcoming United States Food Safety and Inspection Service (FSIS) baseline study to enumerate Campylobacter...

Optimal design of experiments applied to headspace solid phase microextraction for the quantification of vicinal diketones in beer through gas chromatography-mass spectrometric detection.

PubMed

Leça, João M; Pereira, Ana C; Vieira, Ana C; Reis, Marco S; Marques, José C

2015-08-05

Vicinal diketones, namely diacetyl (DC) and pentanedione (PN), are compounds naturally found in beer that play a key role in the definition of its aroma. In lager beer, they are responsible for off-flavors (buttery flavor) and therefore their presence and quantification is of paramount importance to beer producers. Aiming at developing an accurate quantitative monitoring scheme to follow these off-flavor compounds during beer production and in the final product, the head space solid-phase microextraction (HS-SPME) analytical procedure was tuned through experiments planned in an optimal way and the final settings were fully validated. Optimal design of experiments (O-DOE) is a computational, statistically-oriented approach for designing experiences that are most informative according to a well-defined criterion. This methodology was applied for HS-SPME optimization, leading to the following optimal extraction conditions for the quantification of VDK: use a CAR/PDMS fiber, 5 ml of samples in 20 ml vial, 5 min of pre-incubation time followed by 25 min of extraction at 30 °C, with agitation. The validation of the final analytical methodology was performed using a matrix-matched calibration, in order to minimize matrix effects. The following key features were obtained: linearity (R(2) > 0.999, both for diacetyl and 2,3-pentanedione), high sensitivity (LOD of 0.92 μg L(-1) and 2.80 μg L(-1), and LOQ of 3.30 μg L(-1) and 10.01 μg L(-1), for diacetyl and 2,3-pentanedione, respectively), recoveries of approximately 100% and suitable precision (repeatability and reproducibility lower than 3% and 7.5%, respectively). The applicability of the methodology was fully confirmed through an independent analysis of several beer samples, with analyte concentrations ranging from 4 to 200 g L(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

Strategy for design NIR calibration sets based on process spectrum and model space: An innovative approach for process analytical technology.

PubMed

Cárdenas, V; Cordobés, M; Blanco, M; Alcalà, M

2015-10-10

The pharmaceutical industry is under stringent regulations on quality control of their products because is critical for both, productive process and consumer safety. According to the framework of "process analytical technology" (PAT), a complete understanding of the process and a stepwise monitoring of manufacturing are required. Near infrared spectroscopy (NIRS) combined with chemometrics have lately performed efficient, useful and robust for pharmaceutical analysis. One crucial step in developing effective NIRS-based methodologies is selecting an appropriate calibration set to construct models affording accurate predictions. In this work, we developed calibration models for a pharmaceutical formulation during its three manufacturing stages: blending, compaction and coating. A novel methodology is proposed for selecting the calibration set -"process spectrum"-, into which physical changes in the samples at each stage are algebraically incorporated. Also, we established a "model space" defined by Hotelling's T(2) and Q-residuals statistics for outlier identification - inside/outside the defined space - in order to select objectively the factors to be used in calibration set construction. The results obtained confirm the efficacy of the proposed methodology for stepwise pharmaceutical quality control, and the relevance of the study as a guideline for the implementation of this easy and fast methodology in the pharma industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of biomass burning tracers in air samples by GC/MS

NASA Astrophysics Data System (ADS)

Janoszka, Katarzyna

2018-01-01

Levoglucosan (LG) as a main cellulose burning product at 300°C is a biomass burning tracer. LG characterize by relatively high molar mass and it is sorbed by particulate matter. In the study of air pollution monitoring LG is mainly analyzed in particulate matter, PM1 and PM2,5. The tracer create relatively high O-H…O bond and weaker C-H…O bond. Due to the hydrogen bond, LG dissolves very well in water. Analytical procedure of LG determination include: extraction, derivatization and analysis by gas chromatography coupled with mass spectrometry detector. In water samples levoglucosan is determined by liquid chromatography. The paper presents a methodology for particulate matter samples determination their analysis by gas chromatography coupled with a mass spectrometry detector. Determination of LG content in particulate matter was performed according to an analytical method based on simultaneous pyridine extraction and derivatization using N,O-bis (trimethylsilyl) trifluoroacetamide and trimethylchlorosilane mixture (BSTFA: TMCS, 99: 1).

Non-traditional applications of laser desorption/ionization mass spectrometry

NASA Astrophysics Data System (ADS)

McAlpin, Casey R.

Seven studies were carried out using laser desorption/ionization mass spectrometry (LDI MS) to develop enhanced methodologies for a variety of analyte systems by investigating analyte chemistries, ionization processes, and elimination of spectral interferences. Applications of LDI and matrix assisted laser/desorption/ionization (MALDI) have been previously limited by poorly understood ionization phenomena, and spectral interferences from matrices. Matrix assisted laser desorption ionization MS is well suited to the analysis of proteins. However, the proteins associated with bacteriophages often form complexes which are too massive for detection with a standard MALDI mass spectrometer. As such, methodologies for pretreatment of these samples are discussed in detail in the first chapter. Pretreatment of bacteriophage samples with reducing agents disrupted disulfide linkages and allowed enhanced detection of bacteriophage proteins. The second chapter focuses on the use of MALDI MS for lipid compounds whose molecular mass is significantly less than the proteins for which MALDI is most often applied. The use of MALDI MS for lipid analysis presented unique challenges such as matrix interference and differential ionization efficiencies. It was observed that optimization of the matrix system, and addition of cationization reagents mitigated these challenges and resulted in an enhanced methodology for MALDI MS of lipids. One of the challenges commonly encountered in efforts to expand MALDI MS applications is as previously mentioned interferences introduced by organic matrix molecules. The third chapter focuses on the development of a novel inorganic matrix replacement system called metal oxide laser ionization mass spectrometry (MOLI MS). In contrast to other matrix replacements, considerable effort was devoted to elucidating the ionization mechanism. It was shown that chemisorption of analytes to the metal oxide surface produced acidic adsorbed species which then protonated free analyte molecules. Expanded applications of MOLI MS were developed following description of the ionization mechanism. A series of experiments were carried out involving treatment of metal oxide surfaces with reagent molecules to expand MOLI MS and develop enhanced MOLI MS methodologies. It was found that treatment of the metal oxide surface with a small molecule to act as a proton source expanded MOLI MS to analytes which did not form acidic adsorbed species. Proton-source pretreated MOLI MS was then used for the analysis of oils obtained from the fast, anoxic pyrolysis of biomass (py-oil). These samples are complex and produce MOLI mass spectra with many peaks. In this experiment, methods of data reduction including Kendrick mass defects and nominal mass z*-scores, which are commonly used for the study of petroleum fractions, were used to interpret these spectra and identify the major constituencies of py-oils. Through data reduction and collision induced dissociation (CID), homologous series of compounds were rapidly identified. The final chapter involves using metal oxides to catalytically cleave the ester linkage on lipids containing fatty acids in addition to ionization. The cleavage process results in the production of spectra similar to those observed with saponification/methylation. Fatty acid profiles were generated for a variety of micro-organisms to differentiate between bacterial species. (Abstract shortened by UMI.)

Methodological considerations in using complex survey data: an applied example with the Head Start Family and Child Experiences Survey.

PubMed

Hahs-Vaughn, Debbie L; McWayne, Christine M; Bulotsky-Shearer, Rebecca J; Wen, Xiaoli; Faria, Ann-Marie

2011-06-01

Complex survey data are collected by means other than simple random samples. This creates two analytical issues: nonindependence and unequal selection probability. Failing to address these issues results in underestimated standard errors and biased parameter estimates. Using data from the nationally representative Head Start Family and Child Experiences Survey (FACES; 1997 and 2000 cohorts), three diverse multilevel models are presented that illustrate differences in results depending on addressing or ignoring the complex sampling issues. Limitations of using complex survey data are reported, along with recommendations for reporting complex sample results. © The Author(s) 2011

On-line solid phase extraction using the Prospekt-2 coupled with a liquid chromatography/tandem mass spectrometer for the determination of dextromethorphan, dextrorphan and guaifenesin in human plasma.

PubMed

Kuhlenbeck, Debbie L; Eichold, Thomas H; Hoke, Steven H; Baker, Timothy R; Mensen, Robert; Wehmeyer, Kenneth R

2005-01-01

An on-line liquid chromatography/tandem mass spectrometry (LC-MS/MS) procedure, using the Prospekt- 2 system, was developed and used for the determination of the levels of the active ingredients of cough/cold medications in human plasma matrix. The experimental configuration allows direct plasma injection by performing on- line solid phase extraction (SPE) on small cartridge columns prior to elution of the analyte(s) onto the analytical column and subsequent MS/MS detection. The quantitative analysis of three analytes with differing polarities, dextromethorphan (DEX), dextrorphan (DET) and guaifenesin (GG) in human plasma presented a significant challenge. Using stable-isotope-labeled internal standards for each analyte, the Prospekt-2 on-line methodology was evaluated for sensitivity, suppression, accuracy, precision, linearity, analyst time, analysis time, cost, carryover and ease of use. The lower limit of quantitation for the on-line SPE procedure for DEX, DET and GG was 0.05, 0.05 and 5.0 ng mL(-1), respectively, using a 0.1 mL sample volume. The linear range for DEX and DET was 0.05-50 ng mL(-1) and was 5-5,000 ng mL(-1) for GG. Accuracy and precision data for five different levels of QC samples were collected over three separate days. Accuracy ranged from 90% to 112% for all three analytes, while the precision, as measured by the %RSD, ranged from 1.5% to 16.0%

Fifteen years of external quality assessment in leukemia/lymphoma immunophenotyping in The Netherlands and Belgium: A way forward.

PubMed

Preijers, Frank W M B; van der Velden, Vincent H J; Preijers, Tim; Brooimans, Rik A; Marijt, Erik; Homburg, Christa; van Montfort, Kees; Gratama, Jan W

2016-05-01

In 1985, external quality assurance was initiated in the Netherlands to reduce the between-laboratory variability of leukemia/lymphoma immunophenotyping and to improve diagnostic conclusions. This program consisted of regular distributions of test samples followed by biannual plenary participant meetings in which results were presented and discussed. A scoring system was developed in which the quality of results was rated by systematically reviewing the pre-analytical, analytical, and post-analytical assay stages using three scores, i.e., correct (A), minor fault (B), and major fault (C). Here, we report on 90 consecutive samples distributed to 40-61 participating laboratories between 1998 and 2012. Most samples contained >20% aberrant cells, mainly selected from mature lymphoid malignancies (B or T cell) and acute leukemias (myeloid or lymphoblastic). In 2002, minimally required monoclonal antibody (mAb) panels were introduced, whilst methodological guidelines for all three assay stages were implemented. Retrospectively, we divided the study into subsequent periods of 4 ("initial"), 4 ("learning"), and 7 years ("consolidation") to detect "learning effects." Uni- and multivariate models showed that analytical performance declined since 2002, but that post-analytical performance improved during the entire period. These results emphasized the need to improve technical aspects of the assay, and reflected improved interpretational skills of the participants. A strong effect of participant affiliation in all three assay stages was observed: laboratories in academic and large peripheral hospitals performed significantly better than those in small hospitals. © 2015 International Clinical Cytometry Society. © 2015 International Clinical Cytometry Society.

Estimating the uncertainty from sampling in pollution crime investigation: The importance of metrology in the forensic interpretation of environmental data.

PubMed

Barazzetti Barbieri, Cristina; de Souza Sarkis, Jorge Eduardo

2018-07-01

The forensic interpretation of environmental analytical data is usually challenging due to the high geospatial variability of these data. The measurements' uncertainty includes contributions from the sampling and from the sample handling and preparation processes. These contributions are often disregarded in analytical techniques results' quality assurance. A pollution crime investigation case was used to carry out a methodology able to address these uncertainties in two different environmental compartments, freshwater sediments and landfill leachate. The methodology used to estimate the uncertainty was the duplicate method (that replicates predefined steps of the measurement procedure in order to assess its precision) and the parameters used to investigate the pollution were metals (Cr, Cu, Ni, and Zn) in the leachate, the suspect source, and in the sediment, the possible sink. The metal analysis results were compared to statutory limits and it was demonstrated that Cr and Ni concentrations in sediment samples exceeded the threshold levels at all sites downstream the pollution sources, considering the expanded uncertainty U of the measurements and a probability of contamination >0.975, at most sites. Cu and Zn concentrations were above the statutory limits at two sites, but the classification was inconclusive considering the uncertainties of the measurements. Metal analyses in leachate revealed that Cr concentrations were above the statutory limits with a probability of contamination >0.975 in all leachate ponds while the Cu, Ni and Zn probability of contamination was below 0.025. The results demonstrated that the estimation of the sampling uncertainty, which was the dominant component of the combined uncertainty, is required for a comprehensive interpretation of the environmental analyses results, particularly in forensic cases. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid monitoring of residual UV-stabilizers in seawater samples from beaches using fabric phase sorptive extraction and UHPLC-MS/MS.

PubMed

García-Guerra, Romualdo B; Montesdeoca-Esponda, Sarah; Sosa-Ferrera, Zoraida; Kabir, Abuzar; Furton, Kenneth G; Santana-Rodríguez, José Juan

2016-12-01

Benzotriazole UV stabilizers (BUVSs) are a group of compounds added to personal care products such as sunscreens, hair dyes, make up formulations, soaps or shampoos, among others. Direct input from beaches or another aquatic recreational areas is the main source of BUVSs incorporation to the environment, where they can be mutagenic, toxic, pseudo-persistent and bioaccumulative. Due to the low levels of concentration of these compounds found in environmental samples, an extraction process is required prior to their determination. Fabric phase sorptive extraction integrates the advanced material properties of sol-gel hybrid inorganic-organic sorbents with flexible, permeable and functionally active fabric substrates, being a highly responsive, efficient and cheap device that also can be reused. In this paper, we applied fabric phase sorptive extraction methodology to analyse six BUVSs in twenty-four seawater samples from different coastal areas of Gran Canaria Island (Spain). It was coupled to ultra high performance liquid chromatography with tandem mass spectrometry in order to achieve a fast, reliable and sensitive separation and determination of the analytes from different simple matrices, regardless of its complexity and composition. Under the optimum conditions, the proposed method provided enrichment factors of 25 times with limits of detection from 1.06 to 8.96 ng L -1 and limits of quantification from 3.54 to 29.9 ng L -1 for the analytes under study in spiked samples. Intra and inter-day relative standard deviations were between 3.97 and 20.8% for all compounds. The application of the optimized methodology to non-spiked seawater samples allows detecting and quantifying the UV 360 in the range from 41.12 to 544.9 ng L -1 . Copyright © 2016 Elsevier Ltd. All rights reserved.

Studies on the Presence of Mycotoxins in Biological Samples: An Overview

PubMed Central

Escrivá, Laura; Font, Guillermina; Manyes, Lara

2017-01-01

Mycotoxins are fungal secondary metabolites with bioaccumulation levels leading to their carry-over into animal fluids, organs, and tissues. As a consequence, mycotoxin determination in biological samples from humans and animals has been reported worldwide. Since most mycotoxins show toxic effects at low concentrations and considering the extremely low levels present in biological samples, the application of reliable detection methods is required. This review summarizes the information regarding the studies involving mycotoxin determination in biological samples over the last 10 years. Relevant data on extraction methodology, detection techniques, sample size, limits of detection, and quantitation are presented herein. Briefly, liquid-liquid extraction followed by LC-MS/MS determination was the most common technique. The most analyzed mycotoxin was ochratoxin A, followed by zearalenone and deoxynivalenol—including their metabolites, enniatins, fumonisins, aflatoxins, T-2 and HT-2 toxins. Moreover, the studies were classified by their purpose, mainly focused on the development of analytical methodologies, mycotoxin biomonitoring, and exposure assessment. The study of tissue distribution, bioaccumulation, carry-over, persistence and transference of mycotoxins, as well as, toxicokinetics and ADME (absorption, distribution, metabolism and excretion) were other proposed goals for biological sample analysis. Finally, an overview of risk assessment was discussed. PMID:28820481

Resolution of plasma sample mix-ups through comparison of patient antibody patterns to E. coli.

PubMed

Vetter, Beatrice N; Orlowski, Vanessa; Schüpbach, Jörg; Böni, Jürg; Rühe, Bettina; Huder, Jon B

2015-12-01

Accidental sample mix-ups and the need for their swift resolution is a challenge faced by every analytical laboratory. To this end, we developed a simple immunoblot-based method, making use of a patient's characteristic plasma antibody profile to Escherichia coli (E. coli) proteins. Nitrocellulose strips of size-separated proteins from E. coli whole-cell lysates were incubated with patient plasma and visualised with an enzyme-coupled secondary antibody and substrate. Plasma samples of 20 random patients as well as five longitudinal samples of three patients were analysed for antibody band patterns, to evaluate uniqueness and consistency over time, respectively. For sample mix-ups, antibody band patterns of questionable samples were compared with samples of known identity. Comparison of anti-E. coli antibody patterns of 20 random patients showed a unique antibody profile for each patient. Antibody profiles remained consistent over time, as shown for three patients over several years. Three example cases demonstrate the use of this methodology in mis-labelling or -pipetting incidences. Our simple method for resolving plasma sample mix-ups between non-related individuals can be performed with basic laboratory equipment and thus can easily be adopted by analytical laboratories. Copyright © 2015 Elsevier B.V. All rights reserved.

Recent Methodology in Ginseng Analysis

PubMed Central

Baek, Seung-Hoon; Bae, Ok-Nam; Park, Jeong Hill

2012-01-01

As much as the popularity of ginseng in herbal prescriptions or remedies, ginseng has become the focus of research in many scientific fields. Analytical methodologies for ginseng, referred to as ginseng analysis hereafter, have been developed for bioactive component discovery, phytochemical profiling, quality control, and pharmacokinetic studies. This review summarizes the most recent advances in ginseng analysis in the past half-decade including emerging techniques and analytical trends. Ginseng analysis includes all of the leading analytical tools and serves as a representative model for the analytical research of herbal medicines. PMID:23717112

Ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the determination of 4 designer benzodiazepines in urine samples by gas chromatography-triple quadrupole mass spectrometry.

PubMed

Meng, Liang; Zhu, Binling; Zheng, Kefang; Fu, Shanlin

2017-05-15

A novel microextraction technique based on ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) had been applied for the determination of 4 designer benzodiazepines (phenazepam, diclazepam, flubromazepam and etizolam) in urine samples by gas chromatography- triple quadrupole mass spectrometry (GC-QQQ-MS). Ethyl acetate (168μL) was added into the urine samples after adjusting pH to 11.3. The samples were sonicated in an ultrasonic bath for 5.5min to form a cloudy suspension. After centrifugation at 10000rpm for 3min, the supernatant extractant was withdrawn and injected into the GC-QQQ-MS for analysis. Parameters affecting the extraction efficiency have been investigated and optimized by means of single factor experiment and response surface methodology (Box-Behnken design). Under the optimum extraction conditions, a recovery of 73.8-85.5% were obtained for all analytes. The analytical method was linear for all analytes in the range from 0.003 to 10μg/mL with the correlation coefficient ranging from 0.9978 to 0.9990. The LODs were estimated to be 1-3ng/mL. The accuracy (expressed as mean relative error MRE) was within ±5.8% and the precision (expressed as relative standard error RSD) was less than 5.9%. UA-LDS-DLLME technique has the advantages of shorter extraction time and is suitable for simultaneous pretreatment of samples in batches. The combination of UA-LDS-DLLME with GC-QQQ-MS offers an alternative analytical approach for the sensitive detection of these designer benzodiazepines in urine matrix for clinical and medico-legal purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

Alzheimer's disease cerebrospinal fluid biomarkers are not influenced by gravity drip or aspiration extraction methodology.

PubMed

Rembach, Alan; Evered, Lisbeth A; Li, Qiao-Xin; Nash, Tabitha; Vidaurre, Lesley; Fowler, Christopher J; Pertile, Kelly K; Rumble, Rebecca L; Trounson, Brett O; Maher, Sarah; Mooney, Francis; Farrow, Maree; Taddei, Kevin; Rainey-Smith, Stephanie; Laws, Simon M; Macaulay, S Lance; Wilson, William; Darby, David G; Martins, Ralph N; Ames, David; Collins, Steven; Silbert, Brendan; Masters, Colin L; Doecke, James D

2015-11-19

Cerebrospinal fluid (CSF) biomarkers, although of established utility in the diagnostic evaluation of Alzheimer's disease (AD), are known to be sensitive to variation based on pre-analytical sample processing. We assessed whether gravity droplet collection versus syringe aspiration was another factor influencing CSF biomarker analyte concentrations and reproducibility. Standardized lumbar puncture using small calibre atraumatic spinal needles and CSF collection using gravity fed collection followed by syringe aspirated extraction was performed in a sample of elderly individuals participating in a large long-term observational research trial. Analyte assay concentrations were compared. For the 44 total paired samples of gravity collection and aspiration, reproducibility was high for biomarker CSF analyte assay concentrations (concordance correlation [95%CI]: beta-amyloid1-42 (Aβ42) 0.83 [0.71 - 0.90]), t-tau 0.99 [0.98 - 0.99], and phosphorylated tau (p-tau) 0.82 [95 % CI 0.71 - 0.89]) and Bonferroni corrected paired sample t-tests showed no significant differences (group means (SD): Aβ42 366.5 (86.8) vs 354.3 (82.6), p = 0.10; t-tau 83.9 (46.6) vs 84.7 (47.4) p = 0.49; p-tau 43.5 (22.8) vs 40.0 (17.7), p = 0.05). The mean duration of collection was 10.9 minutes for gravity collection and <1 minute for aspiration. Our results demonstrate that aspiration of CSF is comparable to gravity droplet collection for AD biomarker analyses but could considerably accelerate throughput and improve the procedural tolerability for assessment of CSF biomarkers.

Conventional and accelerated-solvent extractions of green tea (camellia sinensis) for metabolomics-based chemometrics.

PubMed

Kellogg, Joshua J; Wallace, Emily D; Graf, Tyler N; Oberlies, Nicholas H; Cech, Nadja B

2017-10-25

Metabolomics has emerged as an important analytical technique for multiple applications. The value of information obtained from metabolomics analysis depends on the degree to which the entire metabolome is present and the reliability of sample treatment to ensure reproducibility across the study. The purpose of this study was to compare methods of preparing complex botanical extract samples prior to metabolomics profiling. Two extraction methodologies, accelerated solvent extraction and a conventional solvent maceration, were compared using commercial green tea [Camellia sinensis (L.) Kuntze (Theaceae)] products as a test case. The accelerated solvent protocol was first evaluated to ascertain critical factors influencing extraction using a D-optimal experimental design study. The accelerated solvent and conventional extraction methods yielded similar metabolite profiles for the green tea samples studied. The accelerated solvent extraction yielded higher total amounts of extracted catechins, was more reproducible, and required less active bench time to prepare the samples. This study demonstrates the effectiveness of accelerated solvent as an efficient methodology for metabolomics studies. Copyright © 2017. Published by Elsevier B.V.

Speciated arsenic in air: measurement methodology and risk assessment considerations.

PubMed

Lewis, Ari S; Reid, Kim R; Pollock, Margaret C; Campleman, Sharan L

2012-01-01

Accurate measurement of arsenic (As) in air is critical to providing a more robust understanding of arsenic exposures and associated human health risks. Although there is extensive information available on total arsenic in air, less is known on the relative contribution of each arsenic species. To address this data gap, the authors conducted an in-depth review of available information on speciated arsenic in air. The evaluation included the type of species measured and the relative abundance, as well as an analysis of the limitations of current analytical methods. Despite inherent differences in the procedures, most techniques effectively separated arsenic species in the air samples. Common analytical techniques such as inductively coupled plasma mass spectrometry (ICP-MS) and/or hydride generation (HG)- or quartz furnace (GF)-atomic absorption spectrometry (AAS) were used for arsenic measurement in the extracts, and provided some of the most sensitive detection limits. The current analysis demonstrated that, despite limited comparability among studies due to differences in seasonal factors, study duration, sample collection methods, and analytical methods, research conducted to date is adequate to show that arsenic in air is mainly in the inorganic form. Reported average concentrations of As(III) and As(V) ranged up to 7.4 and 10.4 ng/m3, respectively, with As(V) being more prevalent than As(III) in most studies. Concentrations of the organic methylated arsenic compounds are negligible (in the pg/m3 range). However because of the variability in study methods and measurement methodology, the authors were unable to determine the variation in arsenic composition as a function of source or particulate matter (PM) fraction. In this work, the authors include the implications of arsenic speciation in air on potential exposure and risks. The authors conclude that it is important to synchronize sample collection, preparation, and analytical techniques in order to generate data more useful for arsenic inhalation risk assessment, and a more robust documentation of quality assurance/quality control (QA/QC) protocols is necessary to ensure accuracy, precision, representativeness, and comparability.

Evaluation of a handheld point-of-care analyser for measurement of creatinine in cats.

PubMed

Reeve, Jenny; Warman, Sheena; Lewis, Daniel; Watson, Natalie; Papasouliotis, Kostas

2017-02-01

Objectives The aim of the study was to evaluate whether a handheld creatinine analyser (StatSensor Xpress; SSXp), available for human patients, can be used to measure creatinine reliably in cats. Methods Analytical performance was evaluated by determining within- and between-run coefficient of variation (CV, %), total error observed (TE obs , %) and sigma metrics. Fifty client-owned cats presenting for investigation of clinical disease had creatinine measured simultaneously, using SSXp (whole blood and plasma) and a reference instrument (Konelab, serum); 48 paired samples were included in the study. Creatinine correlation between methodologies (SSXp vs Konelab) and sample types (SSXp whole blood vs SSXp plasma ) was assessed by Spearman's correlation coefficient and agreement was determined using Bland-Altman difference plots. Each creatinine value was assigned an IRIS stage (1-4); correlation and agreement between Konelab and SSXp IRIS stages were evaluated. Results Within-run CV (4.23-8.85%), between-run CV (8.95-11.72%), TE obs (22.15-34.92%) and sigma metrics (⩽3) did not meet desired analytical requirements. Correlation between sample types was high (SSXp whole blood vs SSXp plasma ; r = 0.89), and between instruments was high (SSXp whole blood vs Konelab serum ; r = 0.85) to very high (SSXp plasma vs Konelab serum ; r = 0.91). Konelab and SSXp whole blood IRIS scores exhibited high correlation ( r = 0.76). Packed cell volume did not significantly affect SSXp determination of creatinine. Bland-Altman difference plots identified a positive bias for the SSXp (7.13 μmol/l SSXp whole blood ; 20.23 μmol/l SSXp plasma ) compared with the Konelab. Outliers (1/48 whole blood; 2/48 plasma) occurred exclusively at very high creatinine concentrations. The SSXp failed to identify 2/21 azotaemic cats. Conclusions and relevance Analytical performance of the SSXp in feline patients is not considered acceptable. The SSXp exhibited a high to very high correlation compared with the reference methodology but the two instruments cannot be used interchangeably. Improvements in the SSXp analytical performance are needed before its use can be recommended in feline clinical practice.

Detection, characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples.

PubMed

Laborda, Francisco; Bolea, Eduardo; Cepriá, Gemma; Gómez, María T; Jiménez, María S; Pérez-Arantegui, Josefina; Castillo, Juan R

2016-01-21

The increasing demand of analytical information related to inorganic engineered nanomaterials requires the adaptation of existing techniques and methods, or the development of new ones. The challenge for the analytical sciences has been to consider the nanoparticles as a new sort of analytes, involving both chemical (composition, mass and number concentration) and physical information (e.g. size, shape, aggregation). Moreover, information about the species derived from the nanoparticles themselves and their transformations must also be supplied. Whereas techniques commonly used for nanoparticle characterization, such as light scattering techniques, show serious limitations when applied to complex samples, other well-established techniques, like electron microscopy and atomic spectrometry, can provide useful information in most cases. Furthermore, separation techniques, including flow field flow fractionation, capillary electrophoresis and hydrodynamic chromatography, are moving to the nano domain, mostly hyphenated to inductively coupled plasma mass spectrometry as element specific detector. Emerging techniques based on the detection of single nanoparticles by using ICP-MS, but also coulometry, are in their way to gain a position. Chemical sensors selective to nanoparticles are in their early stages, but they are very promising considering their portability and simplicity. Although the field is in continuous evolution, at this moment it is moving from proofs-of-concept in simple matrices to methods dealing with matrices of higher complexity and relevant analyte concentrations. To achieve this goal, sample preparation methods are essential to manage such complex situations. Apart from size fractionation methods, matrix digestion, extraction and concentration methods capable of preserving the nature of the nanoparticles are being developed. This review presents and discusses the state-of-the-art analytical techniques and sample preparation methods suitable for dealing with complex samples. Single- and multi-method approaches applied to solve the nanometrological challenges posed by a variety of stakeholders are also presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Analytical and Numerical Results for an Adhesively Bonded Joint Subjected to Pure Bending

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S., III; Lundgren, Eric

2006-01-01

A one-dimensional, semi-analytical methodology that was previously developed for evaluating adhesively bonded joints composed of anisotropic adherends and adhesives that exhibit inelastic material behavior is further verified in the present paper. A summary of the first-order differential equations and applied joint loading used to determine the adhesive response from the methodology are also presented. The method was previously verified against a variety of single-lap joint configurations from the literature that subjected the joints to cases of axial tension and pure bending. Using the same joint configuration and applied bending load presented in a study by Yang, the finite element analysis software ABAQUS was used to further verify the semi-analytical method. Linear static ABAQUS results are presented for two models, one with a coarse and one with a fine element meshing, that were used to verify convergence of the finite element analyses. Close agreement between the finite element results and the semi-analytical methodology were determined for both the shear and normal stress responses of the adhesive bondline. Thus, the semi-analytical methodology was successfully verified using the ABAQUS finite element software and a single-lap joint configuration subjected to pure bending.

Liquid chromatography-mass spectrometry platform for both small neurotransmitters and neuropeptides in blood, with automatic and robust solid phase extraction

NASA Astrophysics Data System (ADS)

Johnsen, Elin; Leknes, Siri; Wilson, Steven Ray; Lundanes, Elsa

2015-03-01

Neurons communicate via chemical signals called neurotransmitters (NTs). The numerous identified NTs can have very different physiochemical properties (solubility, charge, size etc.), so quantification of the various NT classes traditionally requires several analytical platforms/methodologies. We here report that a diverse range of NTs, e.g. peptides oxytocin and vasopressin, monoamines adrenaline and serotonin, and amino acid GABA, can be simultaneously identified/measured in small samples, using an analytical platform based on liquid chromatography and high-resolution mass spectrometry (LC-MS). The automated platform is cost-efficient as manual sample preparation steps and one-time-use equipment are kept to a minimum. Zwitter-ionic HILIC stationary phases were used for both on-line solid phase extraction (SPE) and liquid chromatography (capillary format, cLC). This approach enabled compounds from all NT classes to elute in small volumes producing sharp and symmetric signals, and allowing precise quantifications of small samples, demonstrated with whole blood (100 microliters per sample). An additional robustness-enhancing feature is automatic filtration/filter back-flushing (AFFL), allowing hundreds of samples to be analyzed without any parts needing replacement. The platform can be installed by simple modification of a conventional LC-MS system.

Robotic voltammetry with carbon nanotube-based sensors: a superb blend for convenient high-quality antimicrobial trace analysis.

PubMed

Theanponkrang, Somjai; Suginta, Wipa; Weingart, Helge; Winterhalter, Mathias; Schulte, Albert

2015-01-01

A new automated pharmacoanalytical technique for convenient quantification of redox-active antibiotics has been established by combining the benefits of a carbon nanotube (CNT) sensor modification with electrocatalytic activity for analyte detection with the merits of a robotic electrochemical device that is capable of sequential nonmanual sample measurements in 24-well microtiter plates. Norfloxacin (NFX) and ciprofloxacin (CFX), two standard fluoroquinolone antibiotics, were used in automated calibration measurements by differential pulse voltammetry (DPV) and accomplished were linear ranges of 1-10 μM and 2-100 μM for NFX and CFX, respectively. The lowest detectable levels were estimated to be 0.3±0.1 μM (n=7) for NFX and 1.6±0.1 μM (n=7) for CFX. In standard solutions or tablet samples of known content, both analytes could be quantified with the robotic DPV microtiter plate assay, with recoveries within ±4% of 100%. And recoveries were as good when NFX was evaluated in human serum samples with added NFX. The use of simple instrumentation, convenience in execution, and high effectiveness in analyte quantitation suggest the merger between automated microtiter plate voltammetry and CNT-supported electrochemical drug detection as a novel methodology for antibiotic testing in pharmaceutical and clinical research and quality control laboratories.

Validated analytical methodology for the simultaneous determination of a wide range of pesticides in human blood using GC-MS/MS and LC-ESI/MS/MS and its application in two poisoning cases.

PubMed

Luzardo, Octavio P; Almeida-González, Maira; Ruiz-Suárez, Norberto; Zumbado, Manuel; Henríquez-Hernández, Luis A; Meilán, María José; Camacho, María; Boada, Luis D

2015-09-01

Pesticides are frequently responsible for human poisoning and often the information on the involved substance is lacking. The great variety of pesticides that could be responsible for intoxication makes necessary the development of powerful and versatile analytical methodologies, which allows the identification of the unknown toxic substance. Here we developed a methodology for simultaneous identification and quantification in human blood of 109 highly toxic pesticides. The application of this analytical scheme would help in minimizing the cost of this type of chemical identification, maximizing the chances of identifying the pesticide involved. In the methodology that we present here, we use a liquid-liquid extraction, followed by one single purification step, and quantitation of analytes by a combination of liquid and gas chromatography, both coupled to triple quadrupole mass spectrometry, which is operated in the mode of multiple reaction monitoring. The methodology has been fully validated, and its applicability has been demonstrated in two recent cases involving one self-poisoning fatality and one non-fatal homicidal attempt. Copyright © 2015 The Chartered Society of Forensic Sciences. Published by Elsevier Ireland Ltd. All rights reserved.

Effects of Sampling Conditions and Environmental Factors on Fecal Volatile Organic Compound Analysis by an Electronic Nose Device

PubMed Central

Berkhout, Daniel J. C.; Benninga, Marc A.; van Stein, Ruby M.; Brinkman, Paul; Niemarkt, Hendrik J.; de Boer, Nanne K. H.; de Meij, Tim G. J.

2016-01-01

Prior to implementation of volatile organic compound (VOC) analysis in clinical practice, substantial challenges, including methodological, biological and analytical difficulties are faced. The aim of this study was to evaluate the influence of several sampling conditions and environmental factors on fecal VOC profiles, analyzed by an electronic nose (eNose). Effects of fecal sample mass, water content, duration of storage at room temperature, fecal sample temperature, number of freeze–thaw cycles and effect of sampling method (rectal swabs vs. fecal samples) on VOC profiles were assessed by analysis of totally 725 fecal samples by means of an eNose (Cyranose320®). Furthermore, fecal VOC profiles of totally 1285 fecal samples from 71 infants born at three different hospitals were compared to assess the influence of center of origin on VOC outcome. We observed that all analyzed variables significantly influenced fecal VOC composition. It was feasible to capture a VOC profile using rectal swabs, although this differed significantly from fecal VOC profiles of similar subjects. In addition, 1285 fecal VOC-profiles could significantly be discriminated based on center of birth. In conclusion, standardization of methodology is necessary before fecal VOC analysis can live up to its potential as diagnostic tool in clinical practice. PMID:27886068

The Identification of Factors Affecting the Development and Practice of School-Based Counseling in Different National Contexts: A Grounded Theory Study Using a Worldwide Sample of Descriptive Journal Articles and Book Chapters

ERIC Educational Resources Information Center

Martin, Ian; Lauterbach, Alexandra; Carey, John

2015-01-01

A grounded theory methodology was used to analyze articles and book chapters describing the development and practice of school-based counseling in 25 different countries in order to identify the factors that affect development and practice. An 11-factor analytic framework was developed. Factors include: Cultural Factors, National Needs, Larger…

Force 2025 and Beyond Strategic Force Design Analytic Model

DTIC Science & Technology

2017-01-12

depiction of the core ideas of our force design model. Figure 1: Description of Force Design Model Figure 2 shows an overview of our methodology ...the F2025B Force Design Analytic Model research conducted by TRAC- MTRY and the Naval Postgraduate School. Our research develops a methodology for...designs. We describe a data development methodology that characterizes the data required to construct a force design model using our approach. We

Test-Retest Reliability of Pediatric Heart Rate Variability: A Meta-Analysis.

PubMed

Weiner, Oren M; McGrath, Jennifer J

2017-01-01

Heart rate variability (HRV), an established index of autonomic cardiovascular modulation, is associated with health outcomes (e.g., obesity, diabetes) and mortality risk. Time- and frequency-domain HRV measures are commonly reported in longitudinal adult and pediatric studies of health. While test-retest reliability has been established among adults, less is known about the psychometric properties of HRV among infants, children, and adolescents. The objective was to conduct a meta-analysis of the test-retest reliability of time- and frequency-domain HRV measures from infancy to adolescence. Electronic searches (PubMed, PsycINFO; January 1970-December 2014) identified studies with nonclinical samples aged ≤ 18 years; ≥ 2 baseline HRV recordings separated by ≥ 1 day; and sufficient data for effect size computation. Forty-nine studies ( N = 5,170) met inclusion criteria. Methodological variables coded included factors relevant to study protocol, sample characteristics, electrocardiogram (ECG) signal acquisition and preprocessing, and HRV analytical decisions. Fisher's Z was derived as the common effect size. Analyses were age-stratified (infant/toddler < 5 years, n = 3,329; child/adolescent 5-18 years, n = 1,841) due to marked methodological differences across the pediatric literature. Meta-analytic results revealed HRV demonstrated moderate reliability; child/adolescent studies ( Z = 0.62, r = 0.55) had significantly higher reliability than infant/toddler studies ( Z = 0.42, r = 0.40). Relative to other reported measures, HF exhibited the highest reliability among infant/toddler studies ( Z = 0.42, r = 0.40), while rMSSD exhibited the highest reliability among child/adolescent studies ( Z = 1.00, r = 0.76). Moderator analyses indicated greater reliability with shorter test-retest interval length, reported exclusion criteria based on medical illness/condition, lower proportion of males, prerecording acclimatization period, and longer recording duration; differences were noted across age groups. HRV is reliable among pediatric samples. Reliability is sensitive to pertinent methodological decisions that require careful consideration by the researcher. Limited methodological reporting precluded several a priori moderator analyses. Suggestions for future research, including standards specified by Task Force Guidelines, are discussed.

Test-Retest Reliability of Pediatric Heart Rate Variability

PubMed Central

Weiner, Oren M.; McGrath, Jennifer J.

2017-01-01

Heart rate variability (HRV), an established index of autonomic cardiovascular modulation, is associated with health outcomes (e.g., obesity, diabetes) and mortality risk. Time- and frequency-domain HRV measures are commonly reported in longitudinal adult and pediatric studies of health. While test-retest reliability has been established among adults, less is known about the psychometric properties of HRV among infants, children, and adolescents. The objective was to conduct a meta-analysis of the test-retest reliability of time- and frequency-domain HRV measures from infancy to adolescence. Electronic searches (PubMed, PsycINFO; January 1970–December 2014) identified studies with nonclinical samples aged ≤ 18 years; ≥ 2 baseline HRV recordings separated by ≥ 1 day; and sufficient data for effect size computation. Forty-nine studies (N = 5,170) met inclusion criteria. Methodological variables coded included factors relevant to study protocol, sample characteristics, electrocardiogram (ECG) signal acquisition and preprocessing, and HRV analytical decisions. Fisher’s Z was derived as the common effect size. Analyses were age-stratified (infant/toddler < 5 years, n = 3,329; child/adolescent 5–18 years, n = 1,841) due to marked methodological differences across the pediatric literature. Meta-analytic results revealed HRV demonstrated moderate reliability; child/adolescent studies (Z = 0.62, r = 0.55) had significantly higher reliability than infant/toddler studies (Z = 0.42, r = 0.40). Relative to other reported measures, HF exhibited the highest reliability among infant/toddler studies (Z = 0.42, r = 0.40), while rMSSD exhibited the highest reliability among child/adolescent studies (Z = 1.00, r = 0.76). Moderator analyses indicated greater reliability with shorter test-retest interval length, reported exclusion criteria based on medical illness/condition, lower proportion of males, prerecording acclimatization period, and longer recording duration; differences were noted across age groups. HRV is reliable among pediatric samples. Reliability is sensitive to pertinent methodological decisions that require careful consideration by the researcher. Limited methodological reporting precluded several a priori moderator analyses. Suggestions for future research, including standards specified by Task Force Guidelines, are discussed. PMID:29307951

Microwave assisted solvent extraction and coupled-column reversed-phase liquid chromatography with UV detection use of an analytical restricted-access-medium column for the efficient multi-residue analysis of acidic pesticides in soils.

PubMed

Hogendoom, E A; Huls, R; Dijkman, E; Hoogerbrugge, R

2001-12-14

A screening method has been developed for the determination of acidic pesticides in various types of soils. Methodology is based on the use of microwave assisted solvent extraction (MASE) for fast and efficient extraction of the analytes from the soils and coupled-column reversed-phase liquid chromatography (LC-LC) with UV detection at 228 nm for the instrumental analysis of uncleaned extracts. Four types of soils, including sand, clay and peat, with a range in organic matter content of 0.3-13% and ten acidic pesticides of different chemical families (bentazone, bromoxynil, metsulfuron-methyl, 2,4-D, MCPA, MCPP, 2,4-DP, 2,4,5-T, 2,4-DB and MCPB) were selected as matrices and analytes, respectively. The method developed included the selection of suitable MASE and LC-LC conditions. The latter consisted of the selection of a 5-microm GFF-II internal surface reversed-phase (ISRP, Pinkerton) analytical column (50 x 4.6 mm, I.D.) as the first column in the RAM-C18 configuration in combination with an optimised linear gradient elution including on-line cleanup of sample extracts and reconditioning of the columns. The method was validated with the analysis of freshly spiked samples and samples with aged residues (120 days). The four types of soils were spiked with the ten acidic pesticides at levels between 20 and 200 microg/kg. Weighted regression of the recovery data showed for most analyte-matrix combinations, including freshly spiked samples and aged residues, that the method provides overall recoveries between 60 and 90% with relative standard deviations of the intra-laboratory reproducibility's between 5 and 25%; LODs were obtained between 5 and 50 microg/kg. Evaluation of the data set with principal component analysis revealed that the parameters (i) increase of organic matter content of the soil samples and (ii) aged residues negatively effect the recovery of the analytes.

Determination of residual acetone and acetone related impurities in drug product intermediates prepared as Spray Dried Dispersions (SDD) using gas chromatography with headspace autosampling (GCHS).

PubMed

Quirk, Emma; Doggett, Adrian; Bretnall, Alison

2014-08-05

Spray Dried Dispersions (SDD) are uniform mixtures of a specific ratio of amorphous active pharmaceutical ingredient (API) and polymer prepared via a spray drying process. Volatile solvents are employed during spray drying to facilitate the formation of the SDD material. Following manufacture, analytical methodology is required to determine residual levels of the spray drying solvent and its associated impurities. Due to the high level of polymer in the SDD samples, direct liquid injection with Gas Chromatography (GC) is not a viable option for analysis. This work describes the development and validation of an analytical approach to determine residual levels of acetone and acetone related impurities, mesityl oxide (MO) and diacetone alcohol (DAA), in drug product intermediates prepared as SDDs using GC with headspace (HS) autosampling. The method development for these analytes presented a number of analytical challenges which had to be overcome before the levels of the volatiles of interest could be accurately quantified. GCHS could be used after two critical factors were implemented; (1) calculation and application of conversion factors to 'correct' for the reactions occurring between acetone, MO and DAA during generation of the headspace volume for analysis, and the addition of an equivalent amount of polymer into all reference solutions used for quantitation to ensure comparability between the headspace volumes generated for both samples and external standards. This work describes the method development and optimisation of the standard preparation, the headspace autosampler operating parameters and the chromatographic conditions, together with a summary of the validation of the methodology. The approach has been demonstrated to be robust and suitable to accurately determine levels of acetone, MO and DAA in SDD materials over the linear concentration range 0.008-0.4μL/mL, with minimum quantitation limits of 20ppm for acetone and MO, and 80ppm for DAA. Copyright © 2014 Elsevier B.V. All rights reserved.

Research education: findings of a study of teaching-learning research using multiple analytical perspectives.

PubMed

Vandermause, Roxanne; Barbosa-Leiker, Celestina; Fritz, Roschelle

2014-12-01

This multimethod, qualitative study provides results for educators of nursing doctoral students to consider. Combining the expertise of an empirical analytical researcher (who uses statistical methods) and an interpretive phenomenological researcher (who uses hermeneutic methods), a course was designed that would place doctoral students in the midst of multiparadigmatic discussions while learning fundamental research methods. Field notes and iterative analytical discussions led to patterns and themes that highlight the value of this innovative pedagogical application. Using content analysis and interpretive phenomenological approaches, together with one of the students, data were analyzed from field notes recorded in real time over the period the course was offered. This article describes the course and the study analysis, and offers the pedagogical experience as transformative. A link to a sample syllabus is included in the article. The results encourage nurse educators of doctoral nursing students to focus educational practice on multiple methodological perspectives. Copyright 2014, SLACK Incorporated.

Normalized inverse characterization of sound absorbing rigid porous media.

PubMed

Zieliński, Tomasz G

2015-06-01

This paper presents a methodology for the inverse characterization of sound absorbing rigid porous media, based on standard measurements of the surface acoustic impedance of a porous sample. The model parameters need to be normalized to have a robust identification procedure which fits the model-predicted impedance curves with the measured ones. Such a normalization provides a substitute set of dimensionless (normalized) parameters unambiguously related to the original model parameters. Moreover, two scaling frequencies are introduced, however, they are not additional parameters and for different, yet reasonable, assumptions of their values, the identification procedure should eventually lead to the same solution. The proposed identification technique uses measured and computed impedance curves for a porous sample not only in the standard configuration, that is, set to the rigid termination piston in an impedance tube, but also with air gaps of known thicknesses between the sample and the piston. Therefore, all necessary analytical formulas for sound propagation in double-layered media are provided. The methodology is illustrated by one numerical test and by two examples based on the experimental measurements of the acoustic impedance and absorption of porous ceramic samples of different thicknesses and a sample of polyurethane foam.

Calculation of catalyst crust thickness from full elemental laser-induced breakdown spectroscopy images

NASA Astrophysics Data System (ADS)

Sorbier, L.; Trichard, F.; Moncayo, S.; Lienemann, C. P.; Motto-Ros, V.

2018-01-01

We propose a methodology to compute the crust thickness of an element in an egg-shell catalyst from a two-dimensional elemental map. The methodology handles two important catalyst shapes: infinite extrudates of arbitrary section and spheres. The methodology is validated with synthetic analytical profiles on simple shapes (cylinder and sphere). Its relative accuracy is shown close to few percent with a decrease inversely proportional to the square root of the number of sampled pixels. The crust thickness obtained by this method from quantitative Pd maps acquired by laser-induced breakdown spectroscopy are comparable with values obtained from electron-probe microanalysis profiles. Some discrepancies are found and are explained by the heterogeneity of the crust thickness within a grain. As a full map is more representative than a single profile, fast mapping and the methodology exposed in this paper are expected to become valuable tools for the development of new generations of egg-shell deposited catalysts.

Effect of modulation of the particle size distributions in the direct solid analysis by total-reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Fernández-Ruiz, Ramón; Friedrich K., E. Josue; Redrejo, M. J.

2018-02-01

The main goal of this work was to investigate, in a systematic way, the influence of the controlled modulation of the particle size distribution of a representative solid sample with respect to the more relevant analytical parameters of the Direct Solid Analysis (DSA) by Total-reflection X-Ray Fluorescence (TXRF) quantitative method. In particular, accuracy, uncertainty, linearity and detection limits were correlated with the main parameters of their size distributions for the following elements; Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Ba and Pb. In all cases strong correlations were finded. The main conclusion of this work can be resumed as follows; the modulation of particles shape to lower average sizes next to a minimization of the width of particle size distributions, produce a strong increment of accuracy, minimization of uncertainties and limit of detections for DSA-TXRF methodology. These achievements allow the future use of the DSA-TXRF analytical methodology for development of ISO norms and standardized protocols for the direct analysis of solids by mean of TXRF.

Analytical strategy for the assessment of the protein glycation status in uremic patients by high-performance liquid chromatography.

PubMed

Floridi, A; Trizza, V; Paolotti, P; Lucarelli, C

1999-06-18

We propose a newly integrated procedure for the analysis of furosine (early glycation product) and pentosidine (glycoxidation end-product) in plasma proteins and the simultaneous assessment of advanced glycation end-product (AGE) peptides and free pentosidine in plasma. In order to determine furosine and protein-linked pentosidine, plasma proteins were hydrolyzed in 8 M HCl and each analyte was purified by solid-phase extraction. Furosine was determined by ion-pair RP-HPLC methodology with isocratic elution and spectrophotometric detection at 280 nm and pentosidine by ion-pair RP-HPLC by using gradient elution and fluorimetric detection at 335/385 nm. To assess free pentosidine concentration and simultaneously evaluate the AGE peptides, an aliquot of plasma sample was diluted and ultrafiltered by using Centricon 10 M(r) < or = 10,000) ultrafiltration membranes. Free pentosidine and AGE peptides were analysed by ion-pair RP-HPLC, by using gradient elution and fluorimetric detection at 385 nm upon excitation at 335 nm. The HPLC methodology has been successfully used for the determination of glycation and glycoxidation protein status in uremic patients.

Hair analysis for abused drugs by capillary zone electrophoresis with field-amplified sample stacking.

PubMed

Tagliaro, F; Manetto, G; Crivellente, F; Scarcella, D; Marigo, M

1998-04-05

The present paper describes the methodological optimisation and validation of a capillary zone electrophoresis method for the determination of morphine, cocaine and 3,4-methylenedioxymethamphetamine (MDMA) in hair, with injection based on field-amplified sample stacking. Diode array UV absorption detection was used to improve analytical selectivity and identification power. Analytical conditions: running buffer 100 mM potassium phosphate adjusted to pH 2.5 with phosphoric acid, applied potential 10 kV, temperature 20 degrees C, injection by electromigration at 10 kV for 10 s, detection by UV absorption at the fixed wavelength of 200 nm or by recording the full spectrum between 190 and 400 nm. Injection conditions: the dried hair extracts were reconstituted with a low-conductivity solvent (0.1 mM formic acid), the injection end of the capillary was dipped in water for 5 s without applying pressure (external rinse step), then a plug of 0.1 mM phosphoric acid was loaded by applying 0.5 psi for 10 s and, finally, the sample was injected electrokinetically at 10 kV for 10 s. Under the described conditions, the limit of detection was 2 ng/ml for MDMA, 8 ng/ml for cocaine and 6 ng/ml for morphine (with a signal-to-noise ratio of 5). The lowest concentration suitable for recording interpretable spectra was about 10-20-times the limit of detection of each analyte. The intraday and day-to-day reproducibility of migration times (n = 6), with internal standardisation, was characterised by R.S.D. values < or = 0.6%; peak area R.S.D.s were better than 10% in intraday and than 15% in day-to-day experiments. Analytical linearity was good with R2 better than 0.9990 for all the analytes.

Defining and Measuring Engagement and Learning in Science: Conceptual, Theoretical, Methodological, and Analytical Issues

ERIC Educational Resources Information Center

Azevedo, Roger

2015-01-01

Engagement is one of the most widely misused and overgeneralized constructs found in the educational, learning, instructional, and psychological sciences. The articles in this special issue represent a wide range of traditions and highlight several key conceptual, theoretical, methodological, and analytical issues related to defining and measuring…

Potential of capillary-column-switching liquid chromatography-tandem mass spectrometry for the quantitative trace analysis of small molecules. Application to the on-line screening of drugs in water.

PubMed

Pitarch, Elena; Hernandez, Felix; ten Hove, Jan; Meiring, Hugo; Niesing, Willem; Dijkman, Ellen; Stolker, Linda; Hogendoorn, Elbert

2004-03-26

We have investigated the potential of capillary-column-switching liquid chromatography coupled to tandem mass spectrometry (cLC-MS-MS) for the quantitative on-line trace analysis of target compounds in aqueous solutions. The technical design of the nano-scale cLC system developed at our Institute for peptide and protein identification has been tested and evaluated for the direct trace analysis of drugs in water samples. Sulphametoxazole, bezafibrate, metoprolol, carbamazepine and bisoprolol occurring frequently in Dutch waters, were selected as test compounds. Adequate conditions for trapping, elution and MS-MS detection were investigated by employing laboratory made 200 microm i.d. capillary columns packed with 5 microm aqua C18 material. In the final cLC-MS-MS conditions, a 1 cm length trapping column and a 4 cm length analytical column were selected. Under these conditions, the target compounds could be directly determined in water down to a level of around 50 ng/l employing only 25 microl of water sample. Validation was done by recovery experiments in ground-, surface- and drinking-water matrices as well as by the analysis of water samples with incurred residues and previously analyzed with a conventional procedure involving off-line solid-phase extraction and narrow-bore LC with MS-MS detection. The new methodology provided recoveries (50-500 ng/l level) between 50 and 114% with RSDs (n = 3, each level) below 20% for most of the compounds. Despite the somewhat less analytical performance in comparison to the conventional procedure, the on-line approach of the new methodology is very suitable for screening of drugs in aqueous samples.

Occurrence of veterinary pharmaceuticals in the aquatic environment in Flanders

NASA Astrophysics Data System (ADS)

Servaes, K.; Vanermen, G.; Seuntjens, P.

2009-04-01

There is a growing interest in the occurrence of pharmaceuticals in the aquatic environment. Pharmaceuticals are classified as so-called ‘emerging pollutants'. ‘Emerging pollutants' are not necessarily new chemical compounds. Often these compounds are already present in the environment for a long time. But, their occurrence and especially their impact on the environment has only recently become clear. Consequently, data on their occurrence are rather scarce. In this study, we focus on the occurrence of veterinary pharmaceuticals in surface water in Flanders. We have only considered active substances administered to cattle, pigs and poultry. Based on the literature and information concerning the use in Belgium, a selection of 25 veterinary pharmaceuticals has been made. This selection consists of the most important antibiotics and antiparasitic substances applied in veterinary medicine in Belgium. We develop an analytical methodology based on UPLC-MS/MS for the detection of these veterinary pharmaceuticals in surface water. Therefore, the mass characteristics as well as the optimum LC conditions will be determined. To obtain limits of detection as low as possible, the samples are concentrated prior to analysis using solid phase extraction (SPE). Different SPE cartridges will be tested during the method development. At first, this SPE sample pre-treatment is performed off-line. In a next step, online SPE is optimized for this purpose. The analytical procedure will be subject to an in-house validation study, thereby determining recovery, repeatability (% RSD), limits of detection and limits of quantification. Finally, the developed methodology will be applied for monitoring the occurrence of veterinary pharmaceuticals in surface water and groundwater in Flanders. These water samples will be taken in areas characterized by intensive cattle breeding. Moreover, the samples will be collected during springtime. In this season, farmers apply manure, stored during winter, onto the fields.

Development of a gas chromatography-mass spectrometry method for the determination of pesticides in gaseous and particulate phases in the atmosphere.

PubMed

Borrás, E; Sánchez, P; Muñoz, A; Tortajada-Genaro, L A

2011-08-05

A reliable multi-residue method for determining gaseous and particulate phase pesticides in atmospheric samples has been developed. This method, based on full scan gas chromatography-mass spectrometry (GC-MS), allowed the proper determination of sixteen relevant pesticides, in a wide range of concentrations and without the influence of interferences. The pesticides were benfluralin, bitertanol, buprofezin, chlorfenvinphos, chlorpyrifos, chlorpyrifos-methyl, ethalfluralin, fenthion, lindane, malathion, methidathion, propachlor, propanil, pyriproxifen, tebuconazol and trifluralin. Comparisons of two types of sampling filters (quartz and glass fibre) and four types of solid-phase cartridges (XAD-2, XAD-4, Florisil and Orbo-49P) showed that the most suitable supports were glass fibre filter for particulate pesticides and XAD-2 and XAD-4 cartridges for gaseous pesticides (>95% recovery). Evaluations of elution solvents for ultrasonic-assisted extraction demonstrated that isooctane is better than ethylacetate, dichloromethane, methanol or a mixture of acetone:hexane (1:1). Recovery assays and the standard addition method were performed to validate the proposed methodology. Moreover, large simulator chamber experiments allowed the best study of the gas-particle partitioning of pesticides for testing the sampling efficiency for the validation of an analytical multiresidue method for pesticides in air. Satisfactory analytical parameters were obtained, with a repeatability of 5±1%, a reproducibility of 13±3% and detection limits of 0.05-0.18 pg m(-3) for the particulate phase and 26-88 pg m(-3) for the gaseous phase. Finally, the methodology was successfully applied to rural and agricultural samples in the Mediterranean area. Copyright © 2011 Elsevier B.V. All rights reserved.

Feasibility of corona discharge ion mobility spectrometry for direct analysis of samples extracted by dispersive liquid-liquid microextraction.

PubMed

Jafari, Mohammad T; Riahi, Farhad

2014-05-23

The capability of corona discharge ionization ion mobility spectrometry (CD-IMS) for direct analysis of the samples extracted by dispersive liquid-liquid microextraction (DLLME) was investigated and evaluated, for the first time. To that end, an appropriate new injection port was designed and constructed, resulting in possibility of direct injection of the known sample volume, without tedious sample preparation steps (e.g. derivatization, solvent evaporation, and re-solving in another solvent…). Malathion as a test compound was extracted from different matrices by a rapid and convenient DLLME method. The positive ion mobility spectra of the extracted malathion were obtained after direct injection of carbon tetrachloride or methanol solutions. The analyte responses were compared and the statistical results revealed the feasibility of direct analysis of the extracted samples in carbon tetrachloride, resulting in a convenient methodology. The coupled method of DLLME-CD-IMS was exhaustively validated in terms of sensitivity, dynamic range, recovery, and enrichment factor. Finally, various real samples of apple, river and underground water were analyzed, all verifying the feasibility and success of the proposed method for the easy extraction of the analyte using DLLME separation before the direct analysis by CD-IMS. Copyright © 2014 Elsevier B.V. All rights reserved.

Eco-analytical Methodology in Environmental Problems Monitoring

NASA Astrophysics Data System (ADS)

Agienko, M. I.; Bondareva, E. P.; Chistyakova, G. V.; Zhironkina, O. V.; Kalinina, O. I.

2017-01-01

Among the problems common to all mankind, which solutions influence the prospects of civilization, the problem of ecological situation monitoring takes very important place. Solution of this problem requires specific methodology based on eco-analytical comprehension of global issues. Eco-analytical methodology should help searching for the optimum balance between environmental problems and accelerating scientific and technical progress. The fact that Governments, corporations, scientists and nations focus on the production and consumption of material goods cause great damage to environment. As a result, the activity of environmentalists is developing quite spontaneously, as a complement to productive activities. Therefore, the challenge posed by the environmental problems for the science is the formation of geo-analytical reasoning and the monitoring of global problems common for the whole humanity. So it is expected to find the optimal trajectory of industrial development to prevent irreversible problems in the biosphere that could stop progress of civilization.

A new procedure of determination of alcohol sulfates and alcohol ethoxysulfates in agricultural soils.

PubMed

Fernández-Ramos, C; Ballesteros, O; Zafra-Gómez, A; Blanc, R; Navalón, A; Crovetto, G; Cantarero, S; Oliver-Rodríguez, B; Vílchez, J L

2013-09-01

The number of analytical methodologies that focus in the determination of alcohol sulfates (AS) and alcohol ethoxysulfates (AES) in terrestrial environment is very limited. In the present work, a new methodology to improve the extraction and determination of AS and AES in agricultural soil samples has been developed. Prior to instrumental analysis, an extraction procedure using pressurized liquid extraction with methanol (PLE) was carried out in order to obtain the highest recoveries and improve sensitivity. The most influential variables affecting the PLE procedure were optimized. Then, the separation and quantification of analytes were performed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The limits of detection (LOD) ranged from 0.03 to 0.08μgg(-1) for AS homologues and in the case of AES ethoxymers from 0.03 to 0.09μgg(-1) for AES-C12Ex and from 0.03 to 0.08μgg(-1) for AES-C14Ex. Matrix-matched calibration was used. Trueness was evaluated by using a spike recovery assay with spiked blank samples, and the recoveries ranged from 98.3% to 101.0% for AS and from 99.9% to 100.1% for AES. The method was satisfactorily applied in a field study designed to evaluate the environmental behavior of these compounds in agricultural soil. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Evaluation of the methods for the determination of nitrites in baby foods according Mexican legislation].

PubMed

Morales Guerrero, Josefina C; García Zepeda, Rodrigo A; Flores Ruvalcaba, Edgar; Martínez Michel, Lorelei

2012-09-01

We evaluated the two methods accepted by the Mexican norm for the determination of nitritesin infant meat-based food with vegetables. We determined the content of nitrites in the infant food, raw materials as well as products from the intermediate stages of production. A reagent blank and a reference sample were included at each analytical run. In addition, we determined the sensitivity, recovery percentage and accuracy of each methodology. Infant food results indicated an important difference in the nitrite content determined under each methodology, due to the persistent presence of turbidity in the extracts. Different treatments were proposed to eliminate the turbidity, but these only managed to reduce it. The turbidity was attributed to carbohydrates which disclosed concentration exhibit a wide dispersion and were below the quantifiable limit under both methodologies; therefore it is not recommended to apply these techniques with food suspected to contain traces of nitrites.

Quantitative Profiling of Endogenous Fat-Soluble Vitamins and Carotenoids in Human Plasma Using an Improved UHPSFC-ESI-MS Interface.

PubMed

Petruzziello, Filomena; Grand-Guillaume Perrenoud, Alexandre; Thorimbert, Anita; Fogwill, Michael; Rezzi, Serge

2017-07-18

Analytical solutions enabling the quantification of circulating levels of liposoluble micronutrients such as vitamins and carotenoids are currently limited to either single or a reduced panel of analytes. The requirement to use multiple approaches hampers the investigation of the biological variability on a large number of samples in a time and cost efficient manner. With the goal to develop high-throughput and robust quantitative methods for the profiling of micronutrients in human plasma, we introduce a novel, validated workflow for the determination of 14 fat-soluble vitamins and carotenoids in a single run. Automated supported liquid extraction was optimized and implemented to simultaneously parallelize 48 samples in 1 h, and the analytes were measured using ultrahigh-performance supercritical fluid chromatography coupled to tandem mass spectrometry in less than 8 min. An improved mass spectrometry interface hardware was built up to minimize the post-decompression volume and to allow better control of the chromatographic effluent density on its route toward and into the ion source. In addition, a specific make-up solvent condition was developed to ensure both analytes and matrix constituents solubility after mobile phase decompression. The optimized interface resulted in improved spray plume stability and conserved matrix compounds solubility leading to enhanced hyphenation robustness while ensuring both suitable analytical repeatability and improved the detection sensitivity. The overall developed methodology gives recoveries within 85-115%, as well as within and between-day coefficient of variation of 2 and 14%, respectively.

A new validated analytical method for the determination of tributyltin in water samples at the quantification level set by the European Union.

PubMed

Devos, Christophe; David, Frank; Sandra, Pat

2012-10-26

According to recent directives of the European Union (EU), limits of quantification (LOQ) for the determination of tributyltin (TBT) in surface waters should be ca. 60 pg/L (ppq). This put very stringent requirements on analytical methodologies; definitely when they have to be applied in a routine environment. Stir bar sorptive extraction (SBSE), followed by thermal desorption (TD) and capillary gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) can provide accurate and precise data at the 2 ng/L level (ppt). For lower concentrations, matrix and reagent interferences together with contamination may provide too high TBT values. A two-dimensional heart-cut GC method was developed to fractionate TBT from interferences. The GC-GC-MS/MS method shows excellent linearity in the range 50 pg/L-4 ng/L, good repeatability (RSD<20% at 200 pg/L), and a limit of detection of 11 pg/L. The method performance is demonstrated with representative samples i.e. harbor water and waste water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Analysis of polar and non-polar VOCs from ambient and source matrices: Development of a new canister autosampler which meets TO-15 QA/QC criteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnett, M.L.W.; Neal, D.; Uchtman, R.

1997-12-31

Approximately 108 of the Hazardous Air Pollutants (HAPs) specified in the 1990 Clean Air Act Amendments are classified as volatile organic compounds (VOCs). Of the 108 VOCs, nearly 35% are oxygenated or polar compounds. While more than one sample introduction technique exists for the analysis of these air toxics, SUMMA{reg_sign} canister sampling is suitable for the most complete range of analytes. A broad concentration range of polar and non-polar species can be analyzed from canisters. A new canister autosampler, the Tekmar AUTOCan{trademark} Elite autosampler, has been developed which incorporates the autosampler and concentrator into a single unit. Analysis of polarmore » and non-polar VOCs has been performed. This paper demonstrates adherence to the technical acceptance objectives outlined in the TO-15 methodology including initial calibration, daily calibration, blank analysis, method detection limits and laboratory control samples. The analytical system consists of a Tekmar AUTOCan{trademark} Elite autosampler interfaced to a Hewlett Packard{reg_sign} 5890/5972 MSD.« less

A methodology to enhance electromagnetic compatibility in joint military operations

NASA Astrophysics Data System (ADS)

Buckellew, William R.

The development and validation of an improved methodology to identify, characterize, and prioritize potential joint EMI (electromagnetic interference) interactions and identify and develop solutions to reduce the effects of the interference are discussed. The methodology identifies potential EMI problems using results from field operations, historical data bases, and analytical modeling. Operational expertise, engineering analysis, and testing are used to characterize and prioritize the potential EMI problems. Results can be used to resolve potential EMI during the development and acquisition of new systems and to develop engineering fixes and operational workarounds for systems already employed. The analytic modeling portion of the methodology is a predictive process that uses progressive refinement of the analysis and the operational electronic environment to eliminate noninterfering equipment pairs, defer further analysis on pairs lacking operational significance, and resolve the remaining EMI problems. Tests are conducted on equipment pairs to ensure that the analytical models provide a realistic description of the predicted interference.

Advances in stir bar sorptive extraction for the determination of acidic pharmaceuticals in environmental water matrices Comparison between polyurethane and polydimethylsiloxane polymeric phases.

PubMed

Silva, Ana Rita M; Portugal, Fátima C M; Nogueira, J M F

2008-10-31

Stir bar sorptive extraction with polyurethane (PU) and polydimethylsiloxane (PDMS) polymeric phases followed by high-performance liquid chromatography with diode array detection [SBSE(PU or PDMS)/HPLC-DAD] was studied for the determination of six acidic pharmaceuticals [o-acetylsalicylic acid (ACA), ibuprofen (IBU), diclofenac sodium (DIC), naproxen (NAP), mefenamic acid (MEF) and gemfibrozil (GEM)], selected as non-steroidal acidic anti-inflammatory drugs and lipid regulators model compounds in environmental water matrices. The main parameters affecting the efficiency of the proposed methodology are fully discussed. Assays performed on 25 mL of water samples spiked at the 10 microg L(-1) level under optimized experimental conditions, yielded recoveries ranging from 45.3+/-9.0% (ACA) to 90.6+/-7.2% (IBU) by SBSE(PU) and 9.8+/-1.6% (NAP) to 73.4+/-5.0% (GEM) by SBSE(PDMS), where the former polymeric phase presented a better affinity to extract these target analytes from water matrices at the trace level. The methodology showed also excellent linear dynamic ranges for the six acidic pharmaceuticals studied, with correlation coefficients higher than 0.9976, limits of detection and quantification between 0.40-1.7 microg L(-1) and 1.5-5.8 microg L(-1), respectively, and suitable precision (RSD <15%). Moreover, the developed methodology was applied for the determination of these target analytes in several environmental matrices, including river, sea and wastewater samples, having achieved good performance and moderate matrix effects. In short, the PU foams demonstrated to be an excellent alternative for the enrichment of the more polar metabolites from water matrices by SBSE, overcoming the limitations of the conventional PDMS phase.

Critical review of dog detection and the influences of physiology, training, and analytical methodologies.

PubMed

Hayes, J E; McGreevy, P D; Forbes, S L; Laing, G; Stuetz, R M

2018-08-01

Detection dogs serve a plethora of roles within modern society, and are relied upon to identify threats such as explosives and narcotics. Despite their importance, research and training regarding detection dogs has involved ambiguity. This is partially due to the fact that the assessment of effectiveness regarding detection dogs continues to be entrenched within a traditional, non-scientific understanding. Furthermore, the capabilities of detection dogs are also based on their olfactory physiology and training methodologies, both of which are hampered by knowledge gaps. Additionally, the future of detection dogs is strongly influenced by welfare and social implications. Most importantly however, is the emergence of progressively inexpensive and efficacious analytical methodologies including gas chromatography related techniques, "e-noses", and capillary electrophoresis. These analytical methodologies provide both an alternative and assistor for the detection dog industry, however the interrelationship between these two detection paradigms requires clarification. These factors, when considering their relative contributions, illustrate a need to address research gaps, formalise the detection dog industry and research process, as well as take into consideration analytical methodologies and their influence on the future status of detection dogs. This review offers an integrated assessment of the factors involved in order to determine the current and future status of detection dogs. Copyright © 2018 Elsevier B.V. All rights reserved.

Volatile organic compounds: sampling methods and their worldwide profile in ambient air.

PubMed

Kumar, Anuj; Víden, Ivan

2007-08-01

The atmosphere is a particularly difficult analytical system because of the very low levels of substances to be analysed, sharp variations in pollutant levels with time and location, differences in wind, temperature and humidity. This makes the selection of an efficient sampling technique for air analysis a key step to reliable results. Generally, methods for volatile organic compounds sampling include collection of the whole air or preconcentration of samples on adsorbents. All the methods vary from each other according to the sampling technique, type of sorbent, method of extraction and identification technique. In this review paper we discuss various important aspects for sampling of volatile organic compounds by the widely used and advanced sampling methods. Characteristics of various adsorbents used for VOCs sampling are also described. Furthermore, this paper makes an effort to comprehensively review the concentration levels of volatile organic compounds along with the methodology used for analysis, in major cities of the world.

A QC approach to the determination of day-to-day reproducibility and robustness of LC-MS methods for global metabolite profiling in metabonomics/metabolomics.

PubMed

Gika, Helen G; Theodoridis, Georgios A; Earll, Mark; Wilson, Ian D

2012-09-01

An approach to the determination of day-to-day analytical robustness of LC-MS-based methods for global metabolic profiling using a pooled QC sample is presented for the evaluation of metabonomic/metabolomic data. A set of 60 urine samples were repeatedly analyzed on five different days and the day-to-day reproducibility of the data obtained was determined. Multivariate statistical analysis was performed with the aim of evaluating variability and selected peaks were assessed and validated in terms of retention time stability, mass accuracy and intensity. The methodology enables the repeatability/reproducibility of extended analytical runs in large-scale studies to be determined, allowing the elimination of analytical (as opposed to biological) variability, in order to discover true patterns and correlations within the data. The day-to-day variability of the data revealed by this process suggested that, for this particular system, 3 days continuous operation was possible without the need for maintenance and cleaning. Variation was generally based on signal intensity changes over the 7-day period of the study, and was mainly a result of source contamination.

Critical evaluation of methodology commonly used in sample collection, storage and preparation for the analysis of pharmaceuticals and illicit drugs in surface water and wastewater by solid phase extraction and liquid chromatography-mass spectrometry.

PubMed

Baker, David R; Kasprzyk-Hordern, Barbara

2011-11-04

The main aim of this manuscript is to provide a comprehensive and critical verification of methodology commonly used for sample collection, storage and preparation in studies concerning the analysis of pharmaceuticals and illicit drugs in aqueous environmental samples with the usage of SPE-LC/MS techniques. This manuscript reports the results of investigations into several sample preparation parameters that to the authors' knowledge have not been reported or have received very little attention. This includes: (i) effect of evaporation temperature and (ii) solvent with regards to solid phase extraction (SPE) extracts; (iii) effect of silanising glassware; (iv) recovery of analytes during vacuum filtration through glass fibre filters and (v) pre LC-MS filter membranes. All of these parameters are vital to develop efficient and reliable extraction techniques; an essential factor given that target drug residues are often present in the aqueous environment at ng L(-1) levels. Presented is also the first comprehensive review of the stability of illicit drugs and pharmaceuticals in wastewater. Among the parameters studied are: time of storage, temperature and pH. Over 60 analytes were targeted including stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors, human urine indicators and their metabolites. The lack of stability of analytes in raw wastewater was found to be significant for many compounds. For instance, 34% of compounds studied reported a stability change >15% after only 12 h in raw wastewater stored at 2 °C; a very important finding given that wastewater is typically collected with the use of 24 h composite samplers. The stability of these compounds is also critical given the recent development of so-called 'sewage forensics' or 'sewage epidemiology' in which concentrations of target drug residues in wastewater are used to back-calculate drug consumption. Without an understanding of stability, under (or over) reporting of consumption estimations may take place. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of analytical methodology for the detection of hormones and their attenuation during aquifer recharge and recovery cycles.

PubMed

de Lima Stebbins, Daniela; Docs, Jon; Lowe, Paula; Cohen, Jason; Lei, Hongxia

2016-05-18

The hormones listed in the screening survey list 2 of the Unregulated Contaminant Monitoring Rule 3 (estrone, 17-β-estradiol, 17-α-ethynylestradiol, 16-α-hydroxyestradiol (estriol), equilin, testosterone and 4-androstene-3,17-dione) were analyzed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Two analytical methods were compared: EPA method 539 and the isotope dilution method. EPA method 539 was successfully utilized in river and drinking water matrices with fortified recoveries of 98.9 to 108.5%. Samples from the Hillsborough River reflected levels below the method detection limit (MDL) for the majority of the analytes, except estrone (E1), which was detected at very low concentrations (<0.5 to 1 ng L(-1)) in the majority of samples. No hormones were detected in drinking water samples. The isotope dilution method was used to analyze reclaimed and aquifer storage and recovery (ASR) water samples as a result of strong matrix/solid phase extraction (SPE) losses observed in these more complex matrices. Most of the compounds were not detected or found at relatively low concentrations in the ASR samples. Attenuation of 50 to 99.1% was observed as a result of the ASR recharge/recovery cycles for most of the hormones, except for estriol (E3). Relatively stable concentrations of E3 were found, with only 10% attenuation at one of the sites and no measureable attenuation at another location. These results have substantiated that while EPA method 539 works well for most environmental samples, the isotope dilution method is more robust when dealing with complex matrices such as reclaimed and ASR samples.

Analytical methodologies for the determination of benzodiazepines in biological samples.

PubMed

Persona, Karolina; Madej, Katarzyna; Knihnicki, Paweł; Piekoszewski, Wojciech

2015-09-10

Benzodiazepine drugs belong to important and most widely used medicaments. They demonstrate such therapeutic properties as anxiolytic, sedative, somnifacient, anticonvulsant, diastolic and muscle relaxant effects. However, despite the fact that benzodiazepines possess high therapeutic index and are considered to be relatively safe, their use can be dangerous when: (1) co-administered with alcohol, (2) co-administered with other medicaments like sedatives, antidepressants, neuroleptics or morphine like substances, (3) driving under their influence, (4) using benzodiazepines non-therapeutically as drugs of abuse or in drug-facilitated crimes. For these reasons benzodiazepines are still studied and determined in a variety of biological materials. In this article, sample preparation techniques which have been applied in analysis of benzodiazepine drugs in biological samples have been reviewed and presented. The next part of the article is focused on a review of analytical methods which have been employed for pharmacological, toxicological or forensic study of this group of drugs in the biological matrices. The review was preceded by a description of the physicochemical properties of the selected benzodiazepines and two, very often coexisting in the same analyzed samples, sedative-hypnotic drugs. Copyright © 2015. Published by Elsevier B.V.

Correlated Raman micro-spectroscopy and scanning electron microscopy analyses of flame retardants in environmental samples: a micro-analytical tool for probing chemical composition, origin and spatial distribution.

PubMed

Ghosal, Sutapa; Wagner, Jeff

2013-07-07

We present correlated application of two micro-analytical techniques: scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS) for the non-invasive characterization and molecular identification of flame retardants (FRs) in environmental dusts and consumer products. The SEM/EDS-RMS technique offers correlated, morphological, molecular, spatial distribution and semi-quantitative elemental concentration information at the individual particle level with micrometer spatial resolution and minimal sample preparation. The presented methodology uses SEM/EDS analyses for rapid detection of particles containing FR specific elements as potential indicators of FR presence in a sample followed by correlated RMS analyses of the same particles for characterization of the FR sub-regions and surrounding matrices. The spatially resolved characterization enabled by this approach provides insights into the distributional heterogeneity as well as potential transfer and exposure mechanisms for FRs in the environment that is typically not available through traditional FR analysis. We have used this methodology to reveal a heterogeneous distribution of highly concentrated deca-BDE particles in environmental dust, sometimes in association with identifiable consumer materials. The observed coexistence of deca-BDE with consumer material in dust is strongly indicative of its release into the environment via weathering/abrasion of consumer products. Ingestion of such enriched FR particles in dust represents a potential for instantaneous exposure to high FR concentrations. Therefore, correlated SEM/RMS analysis offers a novel investigative tool for addressing an area of important environmental concern.

Novel liquid chromatography method based on linear weighted regression for the fast determination of isoprostane isomers in plasma samples using sensitive tandem mass spectrometry detection.

PubMed

Aszyk, Justyna; Kot, Jacek; Tkachenko, Yurii; Woźniak, Michał; Bogucka-Kocka, Anna; Kot-Wasik, Agata

2017-04-15

A simple, fast, sensitive and accurate methodology based on a LLE followed by liquid chromatography-tandem mass spectrometry for simultaneous determination of four regioisomers (8-iso prostaglandin F 2α , 8-iso-15(R)-prostaglandin F 2α , 11β-prostaglandin F 2α , 15(R)-prostaglandin F 2α ) in routine analysis of human plasma samples was developed. Isoprostanes are stable products of arachidonic acid peroxidation and are regarded as the most reliable markers of oxidative stress in vivo. Validation of method was performed by evaluation of the key analytical parameters such as: matrix effect, analytical curve, trueness, precision, limits of detection and limits of quantification. As a homoscedasticity was not met for analytical data, weighted linear regression was applied in order to improve the accuracy at the lower end points of calibration curve. The detection limits (LODs) ranged from 1.0 to 2.1pg/mL. For plasma samples spiked with the isoprostanes at the level of 50pg/mL, intra-and interday repeatability ranged from 2.1 to 3.5% and 0.1 to 5.1%, respectively. The applicability of the proposed approach has been verified by monitoring of isoprostane isomers level in plasma samples collected from young patients (n=8) subjected to hyperbaric hyperoxia (100% oxygen at 280kPa(a) for 30min) in a multiplace hyperbaric chamber. Copyright © 2017 Elsevier B.V. All rights reserved.

[Methodological design for the National Survey Violence Against Women in Mexico].

PubMed

Olaiz, Gustavo; Franco, Aurora; Palma, Oswaldo; Echarri, Carlos; Valdez, Rosario; Herrera, Cristina

2006-01-01

To describe the methodology, the research designs used, the estimation and sample selection, variable definitions, collection instruments, and operative design and analytical procedures for the National Survey Violence Against Women in Mexico. A complex (two-step) cross-sectional study was designed and the qualitative design was carried out using in-depth interviews and participant observation in health care units. We obtained for the quantitative study a total of 26 240 interviews in women users of health services and 2 636 questionnaires for health workers; the survey is representative of the 32 Mexican states. For the qualitative study 26 in-depth interviews were conducted with female users and 60 interviews with health workers in the States of Quintana Roo, Coahuila and the Federal District.

Advances in bioanalytical techniques to measure steroid hormones in serum.

PubMed

French, Deborah

2016-06-01

Steroid hormones are measured clinically to determine if a patient has a pathological process occurring in the adrenal gland, or other hormone responsive organs. They are very similar in structure making them analytically challenging to measure. Additionally, these hormones have vast concentration differences in human serum adding to the measurement complexity. GC-MS was the gold standard methodology used to measure steroid hormones clinically, followed by radioimmunoassay, but that was replaced by immunoassay due to ease of use. LC-MS/MS has now become a popular alternative owing to simplified sample preparation than for GC-MS and increased specificity and sensitivity over immunoassay. This review will discuss these methodologies and some new developments that could simplify and improve steroid hormone analysis in serum.

New methodology for capillary electrophoresis with ESI-MS detection: Electrophoretic focusing on inverse electromigration dispersion gradient. High-sensitivity analysis of sulfonamides in waters.

PubMed

Malá, Zdena; Gebauer, Petr; Boček, Petr

2016-09-07

This article describes for the first time the combination of electrophoretic focusing on inverse electromigration dispersion (EMD) gradient, a new separation principle described in 2010, with electrospray-ionization (ESI) mass spectrometric detection. The separation of analytes along the electromigrating EMD profile proceeds so that each analyte is focused and concentrated within the profile at a particular position given by its pKa and ionic mobility. The proposed methodology combines this principle with the transport of the focused zones to the capillary end by superimposed electromigration, electroosmotic flow and ESI suction, and their detection by the MS detector. The designed electrolyte system based on maleic acid and 2,6-lutidine is suitable to create an inverse EMD gradient of required properties and its components are volatile enough to be compatible with the ESI interface. The characteristic properties of the proposed electrolyte system and of the formed inverse gradient are discussed in detail using calculated diagrams and computer simulations. It is shown that the system is surprisingly robust and allows sensitive analyses of trace amounts of weak acids in the pKa range between approx. 6 and 9. As a first practical application of electrophoretic focusing on inverse EMD gradient, the analysis of several sulfonamides in waters is reported. It demonstrates the potential of the developed methodology for fast and high-sensitivity analyses of ionic trace analytes, with reached LODs around 3 × 10(-9) M (0.8 ng mL(-1)) of sulfonamides in spiked drinking water without any sample pretreatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantification of furanic compounds in coated deep-fried products simulating normal preparation and consumption: optimisation of HS-SPME analytical conditions by response surface methodology.

PubMed

Pérez-Palacios, T; Petisca, C; Melo, A; Ferreira, I M P L V O

2012-12-01

The validation of a method for the simultaneous quantification of furanic compounds in coated deep-fried samples processed and handled as usually consumed is presented. The deep-fried food was grinded using a device that simulates the mastication, and immediately analysed by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry. Parameters affecting the efficiency of HS-SPME procedure were selected by response surface methodology, using a 2(3) full-factorial central composite design. Optimal conditions were achieved using 2g of sample, 3g of NaCl and 40min of absorption time at 37°C. Consistency between predicted and experimented values was observed and quality parameters of the method were established. As a result, furan, 2-furfural, furfuryl alcohol and 2-pentylfuran were, for the first time, simultaneously detected and quantified (5.59, 0.27, 10.48 and 1.77μgg(-1) sample, respectively) in coated deep-fried fish, contributing to a better understanding of the amounts of these compounds in food. Copyright © 2012 Elsevier Ltd. All rights reserved.

Towards a green analytical laboratory: microextraction techniques as a useful tool for the monitoring of polluted soils

NASA Astrophysics Data System (ADS)

Lopez-Garcia, Ignacio; Viñas, Pilar; Campillo, Natalia; Hernandez Cordoba, Manuel; Perez Sirvent, Carmen

2016-04-01

Microextraction techniques are a valuable tool at the analytical laboratory since they allow sensitive measurements of pollutants to be carried out by means of easily available instrumentation. There is a large number of such procedures involving miniaturized liquid-liquid or liquid-solid extractions with the common denominator of using very low amounts (only a few microliters) or even none of organic solvents. Since minimal amounts of reagents are involved, and the generation of residues is consequently minimized, the approach falls within the concept of Green Analytical Chemistry. This general methodology is useful both for inorganic and organic pollutants. Thus, low amounts of metallic ions can be measured without the need of using ICP-MS since this instrument can be replaced by a simple AAS spectrometer which is commonly present in any laboratory and involves low acquisition and maintenance costs. When dealing with organic pollutants, the microextracts obtained can be introduced into liquid or gas chromatographs equipped with common detectors and there is no need for the most sophisticated and expensive mass spectrometers. This communication reports an overview of the advantages of such a methodology, and gives examples for the determination of some particular contaminants in soil and water samples The authors are grateful to the Comunidad Autonóma de la Región de Murcia , Spain (Fundación Séneca, 19888/GERM/15) for financial support

Pressurized hot water extraction followed by miniaturized membrane assisted solvent extraction for the green analysis of alkylphenols in sediments.

PubMed

Salgueiro-González, N; Turnes-Carou, I; Muniategui-Lorenzo, S; López-Mahía, P; Prada-Rodríguez, D

2015-02-27

A novel and Green analytical methodology for the determination of alkylphenols (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol) in sediments was developed and validated. The method was based on pressurized hot water extraction (PHWE) followed by miniaturized membrane assisted solvent extraction (MASE) and liquid chromatography-electrospray ionization tandem mass spectrometry detection (LC-ESI-MS/MS). The extraction conditions were optimized by a Plackett-Burman design in order to minimize the number of assays according to Green principles. Matrix effect was studied and compensated using deuterated labeled standards as surrogate standards for the quantitation of the target compounds. The analytical features of the method were satisfactory: relative recoveries varied between 92 and 103% and repeatability and intermediate precision were <9% for all compounds. Quantitation limits of the method (MQL) ranged from 0.061 (4-n-nonylphenol) to 1.7ngg(-1) dry weight (nonylphenol). Sensitivity, selectivity, automaticity and fastness are the main advantages of the exposed methodology. Reagent consumption, analysis time and waste generation were minimized. The "greenness" of the proposed method was evaluated using an analytical Eco-Scale approach and satisfactory results were obtained. The applicability of the proposed method was demonstrated analysing sediment samples of Galicia coast (NW of Spain) and the ubiquity of alkylphenols in the environment was demonstrated. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of trace rare earth elements in gadolinium aluminate by inductively coupled plasma time of flight mass spectrometry

NASA Astrophysics Data System (ADS)

Saha, Abhijit; Deb, S. B.; Nagar, B. K.; Saxena, M. K.

An analytical methodology was developed for the precise quantification of ten trace rare earth elements (REEs), namely, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm, in gadolinium aluminate (GdAlO3) employing an ultrasonic nebulizer (USN)-desolvating device based inductively coupled plasma mass spectrometry (ICP-MS). A microwave digestion procedure was optimized for digesting 100 mg of the refractory oxide using a mixture of sulphuric acid (H2SO4), phosphoric acid (H3PO4) and water (H2O) with 1400 W power, 10 min ramp and 60 min hold time. An USN-desolvating sample introduction system was employed to enhance analyte sensitivities by minimizing their oxide ion formation in the plasma. Studies on the effect of various matrix concentrations on the analyte intensities revealed that precise quantification of the analytes was possible with matrix level of 250 mg L- 1. The possibility of using indium as an internal standard was explored and applied to correct for matrix effect and variation in analyte sensitivity under plasma operating conditions. Individual oxide ion formation yields were determined in matrix matched solution and employed for correcting polyatomic interferences of light REE (LREE) oxide ions on the intensities of middle and heavy rare earth elements (MREEs and HREEs). Recoveries of ≥ 90% were achieved for the analytes employing standard addition technique. Three real samples were analyzed for traces of REEs by the proposed method and cross validated for Eu and Nd by isotope dilution mass spectrometry (IDMS). The results show no significant difference in the values at 95% confidence level. The expanded uncertainty (coverage factor 1σ) in the determination of trace REEs in the samples were found to be between 3 and 8%. The instrument detection limits (IDLs) and the method detection limits (MDLs) for the ten REEs lie in the ranges 1-5 ng L- 1 and 7-64 μg kg- 1 respectively.

Multi-residue determination of the sorption of illicit drugs and pharmaceuticals to wastewater suspended particulate matter using pressurised liquid extraction, solid phase extraction and liquid chromatography coupled with tandem mass spectrometry.

PubMed

Baker, David R; Kasprzyk-Hordern, Barbara

2011-11-04

Presented is the first comprehensive study of drugs of abuse on suspended particulate matter (SPM) in wastewater. Analysis of SPM is crucial to prevent the under-reporting of the levels of analyte that may be present in wastewater. Analytical methods to date analyse the aqueous part of wastewater samples only, removing SPM through the use of filtration or centrifugation. The development of an analytical method to determine 60 compounds on SPM using a combination of pressurised liquid extraction, solid phase extraction and liquid chromatography coupled with tandem mass spectrometry (PLE-SPE-LC-MS/MS) is reported. The range of compounds monitored included stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors, and their metabolites. The method was successfully validated (parameters studied: linearity and range, recovery, accuracy, reproducibility, repeatability, matrix effects, and limits of detection and quantification). The developed methodology was applied to SPM samples collected at three wastewater treatment plants in the UK. The average proportion of analyte on SPM as opposed to in the aqueous phase was <5% for several compounds including cocaine, benzoylecgonine, MDMA, and ketamine; whereas the proportion was >10% with regard to methadone, EDDP, EMDP, BZP, fentanyl, nortramadol, norpropoxyphene, sildenafil and all antidepressants (dosulepin, amitriptyline, nortriptyline, fluoxetine and norfluoxetine). Consequently, the lack of SPM analysis in wastewater sampling protocol could lead to the under-reporting of the measured concentration of some compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

Analytical capabilities of high performance liquid chromatography - Atmospheric pressure photoionization - Orbitrap mass spectrometry (HPLC-APPI-Orbitrap-MS) for the trace determination of novel and emerging flame retardants in fish.

PubMed

Zacs, D; Bartkevics, V

2015-10-22

A new analytical method was established and validated for the analysis of 27 brominated flame retardants (BFRs), including so called "emerging" and "novel" BFRs (EBFRs and NBFRs) in fish samples. High performance liquid chromatography (HPLC) coupled to Orbitrap mass spectrometry (Orbitrap-MS) employing atmospheric pressure photoionization (APPI) interface operated in negative mode was used for the identification/quantitation of contaminants. HPLC-Orbitrap-MS analysis provided a fast separation of selected analytes within 14 min, thus demonstrating a high throughput processing of samples. The developed methodology was tested by intralaboratory validation in terms of recovery, repeatability, linear calibration ranges, instrumental and method limits of quantitation (i-LOQ and m-LOQ), and where possible, trueness was verified by analysis of certified reference materials (CRMs). Recoveries of analytes were between 80 and 119%, while the repeatability in terms of relative standard deviations (RSDs) was in the range from 1.2 to 15.5%. The measured values for both analyzed CRMs agreed with the provided consensus values, revealing the recovery of reference concentrations in 72-119% range. The elaborated method met the sensitivity criterion according to Commission Recommendation 2014/118/EU on monitoring of BFRs in food products for majority of the compounds. The concentrations of polybrominated diphenyl ethers (PBDEs) in real samples determined by HPLC-APPI-Orbitrap-MS method and validated gas chromatography-high-resolution mass spectrometry (GC-HRMS) method were found to be in a good agreement. Copyright © 2015 Elsevier B.V. All rights reserved.

Reagentless, Structure-Switching, Electrochemical Aptamer-Based Sensors

NASA Astrophysics Data System (ADS)

Schoukroun-Barnes, Lauren R.; Macazo, Florika C.; Gutierrez, Brenda; Lottermoser, Justine; Liu, Juan; White, Ryan J.

2016-06-01

The development of structure-switching, electrochemical, aptamer-based sensors over the past ˜10 years has led to a variety of reagentless sensors capable of analytical detection in a range of sample matrices. The crux of this methodology is the coupling of target-induced conformation changes of a redox-labeled aptamer with electrochemical detection of the resulting altered charge transfer rate between the redox molecule and electrode surface. Using aptamer recognition expands the highly sensitive detection ability of electrochemistry to a range of previously inaccessible analytes. In this review, we focus on the methods of sensor fabrication and how sensor signaling is affected by fabrication parameters. We then discuss recent studies addressing the fundamentals of sensor signaling as well as quantitative characterization of the analytical performance of electrochemical aptamer-based sensors. Although the limits of detection of reported electrochemical aptamer-based sensors do not often reach that of gold-standard methods such as enzyme-linked immunosorbent assays, the operational convenience of the sensor platform enables exciting analytical applications that we address. Using illustrative examples, we highlight recent advances in the field that impact important areas of analytical chemistry. Finally, we discuss the challenges and prospects for this class of sensors.

Comparative study of the vapor analytes of trinitrotoluene (TNT)

NASA Astrophysics Data System (ADS)

Edge, Cindy C.; Gibb, Julie; Dugan, Regina E.

1998-12-01

Trinitrotoluene (TNT) is a high explosive used in most antipersonnel and antitank landmines. The Institute for Biological Detection Systems (IBDS) has developed a quantitative vapor delivery system, termed olfactometer, for conducting canine olfactory research. The research is conducted utilizing dynamic conditions, therefore, it is imperative to evaluate the headspace of TNT to ensure consistency with the dynamic generation of vapor. This study quantified the vapor headspace of military- grade TNT utilizing two different vapor generated methodologies, static and dynamic, reflecting differences between field and laboratory environments. Static vapor collection, which closely mimics conditions found during field detection, is defined as vapor collected in an open-air environment at ambient temperature. Dynamic vapor collection incorporates trapping of gases from a high flow vapor generation cell used during olfactometer operation. Analysis of samples collected by the two methodologies was performed by gas chromatography/mass spectrometry and the results provided information with regard to the constituents detected. However, constituent concentration did vary between the sampling methods. This study provides essential information regarding the vapor constituents associated with the TNT sampled using different sampling methods. These differences may be important in determining the detection signature dogs use to recognize TNT.

Ultrasound-assisted emulsification microextraction for determination of 2,4,6-trichloroanisole in wine samples by gas chromatography tandem mass spectrometry.

PubMed

Fontana, Ariel R; Patil, Sangram H; Banerjee, Kaushik; Altamirano, Jorgelina C

2010-04-28

A fast and effective microextraction technique is proposed for preconcentration of 2,4,6-trichloroanisole (2,4,6-TCA) from wine samples prior gas chromatography tandem mass spectrometric (GC-MS/MS) analysis. The proposed technique is based on ultrasonication (US) for favoring the emulsification phenomenon during the extraction stage. Several variables influencing the relative response of the target analyte were studied and optimized. Under optimal experimental conditions, 2,4,6-TCA was quantitatively extracted achieving enhancement factors (EF) > or = 400 and limits of detection (LODs) 0.6-0.7 ng L(-1) with relative standard deviations (RSDs) < or = 11.3%, when 10 ng L(-1) 2,4,6-TCA standard-wine sample blend was analyzed. The calibration graphs for white and red wine were linear within the range of 5-1000 ng L(-1), and estimation coefficients (r(2)) were > or = 0.9995. Validation of the methodology was carried out by standard addition method at two concentrations (10 and 50 ng L(-1)) achieving recoveries >80% indicating satisfactory robustness of the method. The methodology was successfully applied for determination of 2,4,6-TCA in different wine samples.

A methodology for the assessment of manned flight simulator fidelity

NASA Technical Reports Server (NTRS)

Hess, Ronald A.; Malsbury, Terry N.

1989-01-01

A relatively simple analytical methodology for assessing the fidelity of manned flight simulators for specific vehicles and tasks is offered. The methodology is based upon an application of a structural model of the human pilot, including motion cue effects. In particular, predicted pilot/vehicle dynamic characteristics are obtained with and without simulator limitations. A procedure for selecting model parameters can be implemented, given a probable pilot control strategy. In analyzing a pair of piloting tasks for which flight and simulation data are available, the methodology correctly predicted the existence of simulator fidelity problems. The methodology permitted the analytical evaluation of a change in simulator characteristics and indicated that a major source of the fidelity problems was a visual time delay in the simulation.

Pre-analytical effects of blood sampling and handling in quantitative immunoassays for rheumatoid arthritis.

PubMed

Zhao, Xiaoyan; Qureshi, Ferhan; Eastman, P Scott; Manning, William C; Alexander, Claire; Robinson, William H; Hesterberg, Lyndal K

2012-04-30

Variability in pre-analytical blood sampling and handling can significantly impact results obtained in quantitative immunoassays. Understanding the impact of these variables is critical for accurate quantification and validation of biomarker measurements. Particularly, in the design and execution of large clinical trials, even small differences in sample processing and handling can have dramatic effects in analytical reliability, results interpretation, trial management and outcome. The effects of two common blood sampling methods (serum vs. plasma) and two widely-used serum handling methods (on the clot with ambient temperature shipping, "traditional", vs. centrifuged with cold chain shipping, "protocol") on protein and autoantibody concentrations were examined. Matched serum and plasma samples were collected from 32 rheumatoid arthritis (RA) patients representing a wide range of disease activity status. Additionally, a set of matched serum samples with two sample handling methods was collected. One tube was processed per manufacturer's instructions and shipped overnight on cold packs (protocol). The matched tube, without prior centrifugation, was simultaneously shipped overnight at ambient temperatures (traditional). Upon delivery, the traditional tube was centrifuged. All samples were subsequently aliquoted and frozen prior to analysis of protein and autoantibody biomarkers. Median correlation between paired serum and plasma across all autoantibody assays was 0.99 (0.98-1.00) with a median % difference of -3.3 (-7.5 to 6.0). In contrast, observed protein biomarker concentrations were significantly affected by sample types, with median correlation of 0.99 (0.33-1.00) and a median % difference of -10 (-55 to 23). When the two serum collection/handling methods were compared, the median correlation between paired samples for autoantibodies was 0.99 (0.91-1.00) with a median difference of 4%. In contrast, significant increases were observed in protein biomarker concentrations among certain biomarkers in samples processed with the 'traditional' method. Autoantibody quantification appears robust to both sample type (plasma vs. serum) and pre-analytical sample collection/handling methods (protocol vs. traditional). In contrast, for non-antibody protein biomarker concentrations, sample type had a significant impact; plasma samples generally exhibit decreased protein biomarker concentrations relative to serum. Similarly, sample handling significantly impacted the variability of protein biomarker concentrations. When biomarker concentrations are combined algorithmically into a single test score such as a multi-biomarker disease activity test for rheumatoid arthritis (MBDA), changes in protein biomarker concentrations may result in a bias of the score. These results illustrate the importance of characterizing pre-analytical methodology, sample type, sample processing and handling procedures for clinical testing in order to ensure test accuracy. Copyright © 2012 Elsevier B.V. All rights reserved.

Robotic voltammetry with carbon nanotube-based sensors: a superb blend for convenient high-quality antimicrobial trace analysis

PubMed Central

Theanponkrang, Somjai; Suginta, Wipa; Weingart, Helge; Winterhalter, Mathias; Schulte, Albert

2015-01-01

A new automated pharmacoanalytical technique for convenient quantification of redox-active antibiotics has been established by combining the benefits of a carbon nanotube (CNT) sensor modification with electrocatalytic activity for analyte detection with the merits of a robotic electrochemical device that is capable of sequential nonmanual sample measurements in 24-well microtiter plates. Norfloxacin (NFX) and ciprofloxacin (CFX), two standard fluoroquinolone antibiotics, were used in automated calibration measurements by differential pulse voltammetry (DPV) and accomplished were linear ranges of 1–10 μM and 2–100 μM for NFX and CFX, respectively. The lowest detectable levels were estimated to be 0.3±0.1 μM (n=7) for NFX and 1.6±0.1 μM (n=7) for CFX. In standard solutions or tablet samples of known content, both analytes could be quantified with the robotic DPV microtiter plate assay, with recoveries within ±4% of 100%. And recoveries were as good when NFX was evaluated in human serum samples with added NFX. The use of simple instrumentation, convenience in execution, and high effectiveness in analyte quantitation suggest the merger between automated microtiter plate voltammetry and CNT-supported electrochemical drug detection as a novel methodology for antibiotic testing in pharmaceutical and clinical research and quality control laboratories. PMID:25670899

Impurity profiling of a chemical weapon precursor for possible forensic signatures by comprehensive two-dimensional gas chromatography/mass spectrometry and chemometrics.

PubMed

Hoggard, Jamin C; Wahl, Jon H; Synovec, Robert E; Mong, Gary M; Fraga, Carlos G

2010-01-15

In this report we present the feasibility of using analytical and chemometric methodologies to reveal and exploit the chemical impurity profiles from commercial dimethyl methylphosphonate (DMMP) samples to illustrate the type of forensic information that may be obtained from chemical-attack evidence. Using DMMP as a model compound of a toxicant that may be used in a chemical attack, we used comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOF-MS) to detect and identify trace organic impurities in six samples of commercially acquired DMMP. The GC x GC/TOF-MS data was analyzed to produce impurity profiles for all six DMMP samples using 29 analyte impurities. The use of PARAFAC for the mathematical resolution of overlapped GC x GC peaks ensured clean spectra for the identification of many of the detected analytes by spectral library matching. The use of statistical pairwise comparison revealed that there were trace impurities that were quantitatively similar and different among five of the six DMMP samples. Two of the DMMP samples were revealed to have identical impurity profiles by this approach. The use of nonnegative matrix factorization indicated that there were five distinct DMMP sample types as illustrated by the clustering of the multiple DMMP analyses into five distinct clusters in the scores plots. The two indistinguishable DMMP samples were confirmed by their chemical supplier to be from the same bulk source. Sample information from the other chemical suppliers supported the idea that the other four DMMP samples were likely from different bulk sources. These results demonstrate that the matching of synthesized products from the same source is possible using impurity profiling. In addition, the identified impurities common to all six DMMP samples provide strong evidence that basic route information can be obtained from impurity profiles. Finally, impurities that may be unique to the sole bulk manufacturer of DMMP were found in some of the DMMP samples.

Determination of proline in honey: comparison between official methods, optimization and validation of the analytical methodology.

PubMed

Truzzi, Cristina; Annibaldi, Anna; Illuminati, Silvia; Finale, Carolina; Scarponi, Giuseppe

2014-05-01

The study compares official spectrophotometric methods for the determination of proline content in honey - those of the International Honey Commission (IHC) and the Association of Official Analytical Chemists (AOAC) - with the original Ough method. Results show that the extra time-consuming treatment stages added by the IHC method with respect to the Ough method are pointless. We demonstrate that the AOACs method proves to be the best in terms of accuracy and time saving. The optimized waiting time for the absorbance recording is set at 35min from the removal of reaction tubes from the boiling bath used in the sample treatment. The optimized method was validated in the matrix: linearity up to 1800mgL(-1), limit of detection 20mgL(-1), limit of quantification 61mgL(-1). The method was applied to 43 unifloral honey samples from the Marche region, Italy. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simple and clean determination of tetracyclines by flow injection analysis

NASA Astrophysics Data System (ADS)

Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo

2016-01-01

An environmentally reliable analytical methodology was developed for direct quantification of tetracycline (TC) and oxytetracycline (OTC) using continuous flow injection analysis with spectrophotometric detection. The method is based on the diazo coupling reaction between the tetracyclines and diazotized sulfanilic acid in a basic medium, resulting in the formation of an intense orange azo compound that presents maximum absorption at 434 nm. Experimental design was used to optimize the analytical conditions. The proposed technique was validated over the concentration range of 1 to 40 μg mL- 1, and was successfully applied to samples of commercial veterinary pharmaceuticals. The detection (LOD) and quantification (LOQ) limits were 0.40 and 1.35 μg mL- 1, respectively. The samples were also analyzed by an HPLC method, and the results showed agreement with the proposed technique. The new flow injection method can be immediately used for quality control purposes in the pharmaceutical industry, facilitating monitoring in real time during the production processes of tetracycline formulations for veterinary use.

Development of an analytical scheme for simazine and 2,4-D in soil and water runoff from ornamental plant nursery plots.

PubMed

Sutherland, Devon J; Stearman, G Kim; Wells, Martha J M

2003-01-01

The transport and fate of pesticides applied to ornamental plant nursery crops are not well documented. Methodology for analysis of soil and water runoff samples concomitantly containing the herbicides simazine (1-chloro-4,6-bis(ethylamino)-s-triazine) and 2,4-D ((2,4-dichlorophenoxy)acetic acid) was developed in this research to investigate the potential for runoff and leaching from ornamental nursery plots. Solid-phase extraction was used prior to analysis by gas chromatography and liquid chromatography. Chromatographic results were compared with determination by enzyme-linked immunoassay analysis. The significant analytical contributions of this research include (1) the development of a scheme using chromatographic mode sequencing for the fractionation of simazine and 2,4-D, (2) optimization of the homogeneous derivatization of 2,4-D using the methylating agent boron trifluoride in methanol as an alternative to in situ generation of diazomethane, and (3) the practical application of these techniques to field samples.

Analytical model for real time, noninvasive estimation of blood glucose level.

PubMed

Adhyapak, Anoop; Sidley, Matthew; Venkataraman, Jayanti

2014-01-01

The paper presents an analytical model to estimate blood glucose level from measurements made non-invasively and in real time by an antenna strapped to a patient's wrist. Some promising success has been shown by the RIT ETA Lab research group that an antenna's resonant frequency can track, in real time, changes in glucose concentration. Based on an in-vitro study of blood samples of diabetic patients, the paper presents a modified Cole-Cole model that incorporates a factor to represent the change in glucose level. A calibration technique using the input impedance technique is discussed and the results show a good estimation as compared to the glucose meter readings. An alternate calibration methodology has been developed that is based on the shift in the antenna resonant frequency using an equivalent circuit model containing a shunt capacitor to represent the shift in resonant frequency with changing glucose levels. Work under progress is the optimization of the technique with a larger sample of patients.

Lean six sigma methodologies improve clinical laboratory efficiency and reduce turnaround times.

PubMed

Inal, Tamer C; Goruroglu Ozturk, Ozlem; Kibar, Filiz; Cetiner, Salih; Matyar, Selcuk; Daglioglu, Gulcin; Yaman, Akgun

2018-01-01

Organizing work flow is a major task of laboratory management. Recently, clinical laboratories have started to adopt methodologies such as Lean Six Sigma and some successful implementations have been reported. This study used Lean Six Sigma to simplify the laboratory work process and decrease the turnaround time by eliminating non-value-adding steps. The five-stage Six Sigma system known as define, measure, analyze, improve, and control (DMAIC) is used to identify and solve problems. The laboratory turnaround time for individual tests, total delay time in the sample reception area, and percentage of steps involving risks of medical errors and biological hazards in the overall process are measured. The pre-analytical process in the reception area was improved by eliminating 3 h and 22.5 min of non-value-adding work. Turnaround time also improved for stat samples from 68 to 59 min after applying Lean. Steps prone to medical errors and posing potential biological hazards to receptionists were reduced from 30% to 3%. Successful implementation of Lean Six Sigma significantly improved all of the selected performance metrics. This quality-improvement methodology has the potential to significantly improve clinical laboratories. © 2017 Wiley Periodicals, Inc.

Screening for Triterpenoid Saponins in Plants Using Hyphenated Analytical Platforms.

PubMed

Khakimov, Bekzod; Tseng, Li Hong; Godejohann, Markus; Bak, Søren; Engelsen, Søren Balling

2016-11-24

Recently the number of studies investigating triterpenoid saponins has drastically increased due to their diverse and potentially attractive biological activities. Currently the literature contains chemical structures of few hundreds of triterpenoid saponins of plant and animal origin. Triterpenoid saponins consist of a triterpene aglycone with one or more sugar moieties attached to it. However, due to similar physico-chemical properties, isolation and identification of a large diversity of triterpenoid saponins remain challenging. This study demonstrates a methodology to screen saponins using hyphenated analytical platforms, GC-MS, LC-MS/MS, and LC-SPE-NMR/MS, in the example of two different phenotypes of the model plant Barbarea vulgaris (winter cress), glabrous (G) and pubescent (P) type that are known to differ by their insect resistance. The proposed methodology allows for detailed comparison of saponin profiles from intact plant extracts as well as saponin aglycone profiles from hydrolysed samples. Continuously measured 1D proton NMR data during LC separation along with mass spectrometry data revealed significant differences, including contents of saponins, types of aglycones and numbers of sugar moieties attached to the aglycone. A total of 49 peaks were tentatively identified as saponins from both plants; they are derived from eight types of aglycones and with 2-5 sugar moieties. Identification of two previously known insect-deterrent saponins, hederagenin cellobioside and oleanolic acid cellobioside, demonstrated the applicability of the methodology for relatively rapid screening of bioactive compounds.

The harmful chemistry behind "krokodil": Street-like synthesis and product analysis.

PubMed

Alves, Emanuele Amorim; Soares, José Xavier; Afonso, Carlos Manuel; Grund, Jean-Paul C; Agonia, Ana Sofia; Cravo, Sara Manuela; Netto, Annibal Duarte Pereira; Carvalho, Félix; Dinis-Oliveira, Ricardo Jorge

2015-12-01

"Krokodil" is the street name for a drug, which has been attracting media and researchers attention due to its increasing spread and extreme toxicity. "Krokodil" is a homemade injectable mixture being used as a cheap substitute for heroin. Its use begun in Russia and Ukraine, but it is being spread throughout other countries. The starting materials for "krokodil" synthesis are tablets containing codeine, caustic soda, gasoline, hydrochloric acid, iodine from disinfectants and red phosphorus from matchboxes, all of which are easily available in a retail market or drugstores. The resulting product is a light brown liquid that is injected without previous purification. Herein, we aimed to understand the chemistry behind "krokodil" synthesis by mimicking the steps followed by people who use this drug. The successful synthesis was assessed by the presence of desomorphine and other two morphinans. An analytical gas chromatography-electron impact/mass spectrometry (GC-EI/MS) methodology for quantification of desomorphine and codeine was also developed and validated. The methodologies presented herein provide a representative synthesis of "krokodil" street samples and the application of an effective analytical methodology for desomorphine quantification, which was the major morphinan found. Further studies are required in order to find other hypothetical by-products in "krokodil" since these may help to explain signs and symptoms presented by abusers. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Toxicological importance of human biomonitoring of metallic and metalloid elements in different biological samples.

PubMed

Gil, F; Hernández, A F

2015-06-01

Human biomonitoring has become an important tool for the assessment of internal doses of metallic and metalloid elements. These elements are of great significance because of their toxic properties and wide distribution in environmental compartments. Although blood and urine are the most used and accepted matrices for human biomonitoring, other non-conventional samples (saliva, placenta, meconium, hair, nails, teeth, breast milk) may have practical advantages and would provide additional information on health risk. Nevertheless, the analysis of these compounds in biological matrices other than blood and urine has not yet been accepted as a useful tool for biomonitoring. The validation of analytical procedures is absolutely necessary for a proper implementation of non-conventional samples in biomonitoring programs. However, the lack of reliable and useful analytical methodologies to assess exposure to metallic elements, and the potential interference of external contamination and variation in biological features of non-conventional samples are important limitations for setting health-based reference values. The influence of potential confounding factors on metallic concentration should always be considered. More research is needed to ascertain whether or not non-conventional matrices offer definitive advantages over the traditional samples and to broaden the available database for establishing worldwide accepted reference values in non-exposed populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protein Multiplexed Immunoassay Analysis with R.

PubMed

Breen, Edmond J

2017-01-01

Plasma samples from 177 control and type 2 diabetes patients collected at three Australian hospitals are screened for 14 analytes using six custom-made multiplex kits across 60 96-well plates. In total 354 samples were collected from the patients, representing one baseline and one end point sample from each patient. R methods and source code for analyzing the analyte fluorescence response obtained from these samples by Luminex Bio-Plex ® xMap multiplexed immunoassay technology are disclosed. Techniques and R procedures for reading Bio-Plex ® result files for statistical analysis and data visualization are also presented. The need for technical replicates and the number of technical replicates are addressed as well as plate layout design strategies. Multinomial regression is used to determine plate to sample covariate balance. Methods for matching clinical covariate information to Bio-Plex ® results and vice versa are given. As well as methods for measuring and inspecting the quality of the fluorescence responses are presented. Both fixed and mixed-effect approaches for immunoassay statistical differential analysis are presented and discussed. A random effect approach to outlier analysis and detection is also shown. The bioinformatics R methodology present here provides a foundation for rigorous and reproducible analysis of the fluorescence response obtained from multiplexed immunoassays.

SAN RAFAEL PRIMITIVE AREA, CALIFORNIA.

USGS Publications Warehouse

Gower, H.D.

1984-01-01

No mineral-resource potential was identified during studies of the San Rafael Primitive Area, located at the southern end of the Coast Ranges of California. No petroleum has been produced from the area and there is little promise for the occurrence of energy resources. Limestone occurs in the area but also is found in abundance outside the area. Inasmuch as sampling and analytical techniques have improved significantly since this study was completed a restudy of the area using new methodology is possibly warranted.

Problem Definition Study on Techniques and Methodologies for Evaluating the Chemical and Toxicological Properties of Combustion Products of Gun Systems. Volume 1.

DTIC Science & Technology

1988-03-01

methods that can resolve the various compounds are required. This chapter specifically focuses on analytical and sampling metho - dology used to determine...Salmonella typhimurium TA1538. Cancer Res. 35:2461-2468. Huy, N. D., R. Belleau, and P. E. Roy. 1975. Toxicity of marijuana and tobacco smoking in the... Medicine Division (HSHA-IPM) Fort Sam Houston, TX 78234 Commander U.S. Army Materiel Command ATTN: AMSCG 5001 Eisenhower Avenue Alexandria, VA 22333

Pushing the limits: Quantification of chromophores in real-world paper samples by GC-ECD and EI-GC-MS.

PubMed

Schedl, A; Zweckmair, T; Kikul, F; Bacher, M; Rosenau, T; Potthast, A

2018-03-01

Widening the methodology of chromophore analysis in pulp and paper science, a sensitive gas-chromatographic approach with electron-capture detection is presented and applied to model samples and real-world historic paper material. Trifluoroacetic anhydride was used for derivatization of the chromophore target compounds. The derivative formation was confirmed by NMR and accurate mass analysis. The method successfully detects and quantifies hydroxyquinones which are key chromophores in cellulosic matrices. The analytical figures of merit appeared to be in an acceptable range with an LOD down to approx. 60ng/g for each key chromophore, which allows for their successful detection in historic sample material. Copyright © 2017 Elsevier B.V. All rights reserved.

Extending religion-health research to secular minorities: issues and concerns.

PubMed

Hwang, Karen; Hammer, Joseph H; Cragun, Ryan T

2011-09-01

Claims about religion's beneficial effects on physical and psychological health have received substantial attention in popular media, but empirical support for these claims is mixed. Many of these claims are tenuous because they fail to address basic methodological issues relating to construct validity, sampling methods or analytical problems. A more conceptual problem has to do with the near universal lack of atheist control samples. While many studies include samples of individuals classified as "low spirituality" or religious "nones", these groups are heterogeneous and contain only a fraction of members who would be considered truly secular. We illustrate the importance of including an atheist control group whenever possible in the religiosity/spirituality and health research and discuss areas for further investigation.

WIPP waste characterization program sampling and analysis guidance manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-01-01

The Waste Isolation Pilot Plant (WIPP) Waste Characterization Program Sampling and Analysis Guidance Manual (Guidance Manual) provides a unified source of information on the sampling and analytical techniques that enable Department of Energy (DOE) facilities to comply with the requirements established in the current revision of the Quality Assurance Program Plan (QAPP) for the WIPP Experimental-Waste Characterization Program (the Program). This Guidance Manual includes all of the sampling and testing methodologies accepted by the WIPP Project Office (DOE/WPO) for use in implementing the Program requirements specified in the QAPP. This includes methods for characterizing representative samples of transuranic (TRU) wastesmore » at DOE generator sites with respect to the gas generation controlling variables defined in the WIPP bin-scale and alcove test plans, as well as waste container headspace gas sampling and analytical procedures to support waste characterization requirements under the WIPP test program and the Resource Conservation and Recovery Act (RCRA). The procedures in this Guidance Manual are comprehensive and detailed and are designed to provide the necessary guidance for the preparation of site specific procedures. The use of these procedures is intended to provide the necessary sensitivity, specificity, precision, and comparability of analyses and test results. The solutions to achieving specific program objectives will depend upon facility constraints, compliance with DOE Orders and DOE facilities' operating contractor requirements, and the knowledge and experience of the TRU waste handlers and analysts. With some analytical methods, such as gas chromatography/mass spectrometry, the Guidance Manual procedures may be used directly. With other methods, such as nondestructive/destructive characterization, the Guidance Manual provides guidance rather than a step-by-step procedure.« less

HPLC-DAD method development and validation for the quantification of hydroxymethylfurfural in corn chips by means of response surface optimisation.

PubMed

Salvatierra Virgen, Sara; Ceballos-Magaña, Silvia Guillermina; Salvatierra-Stamp, Vilma Del Carmen; Sumaya-Martínez, Maria Teresa; Martínez-Martínez, Francisco Javier; Muñiz-Valencia, Roberto

2017-12-01

In recent years, there has been an increased concern about the presence of toxic compounds derived from the Maillard reaction produced during food cooking at high temperatures. The main toxic compounds derived from this reaction are acrylamide and hydroxymethylfurfural (HMF). The majority of analytical methods require sample treatments using solvents which are highly polluting for the environment. The difficulty of quantifying HMF in complex fried food matrices encourages the development of new analytical methods. This paper provides a rapid, sensitive and environmentally-friendly analytical method for the quantification of HMF in corn chips using HPLC-DAD. Chromatographic separation resulted in a baseline separation for HMF in 3.7 min. Sample treatment for corn chip samples first involved a leaching process using water and afterwards a solid-phase extraction (SPE) using HLB-Oasis polymeric cartridges. Sample treatment optimisation was carried out by means of Box-Behnken fractional factorial design and Response Surface Methodolog y to examine the effects of four variables (sample weight, pH, sonication time and elution volume) on HMF extraction from corn chips. The SPE-HPLC-DAD method was validated. The limits of detection and quantification were 0.82 and 2.20 mg kg -1 , respectively. Method precision was evaluated in terms of repeatability and reproducibility as relative standard deviations (RSDs) using three concentration levels. For repeatability, RSD values were 6.9, 3.6 and 2.0%; and for reproducibility 18.8, 7.9 and 2.9%. For a ruggedness study the Yuden test was applied and the result demonstrated the method as robust. The method was successfully applied to different corn chip samples.

Effect of Geometry on Electrokinetic Characterization of Solid Surfaces.

PubMed

Kumar, Abhijeet; Kleinen, Jochen; Venzmer, Joachim; Gambaryan-Roisman, Tatiana

2017-08-01

An analytical approach is presented to describe pressure-driven streaming current (I str ) and streaming potential (U str ) generation in geometrically complex samples, for which the classical Helmholtz-Smoluchowski (H-S) equation is known to be inaccurate. The new approach is valid under the same prerequisite conditions that are used for the development of the H-S equation, that is, the electrical double layers (EDLs) are sufficiently thin and surface conductivity and electroviscous effects are negligible. The analytical methodology is developed using linear velocity profiles to describe liquid flow inside of EDLs and using simplifying approximations to describe macroscopic flow. At first, a general expression is obtained to describe the I str generated in different cross sections of an arbitrarily shaped sample. Thereafter, assuming that the generated U str varies only along the pressure-gradient direction, an expression describing the variation of generated U str along the sample length is obtained. These expressions describing I str and U str generation constitute the theoretical foundation of this work, which is first applied to a set of three nonuniform cross-sectional capillaries and thereafter to a square array of cylindrical fibers (model porous media) for both parallel and transverse fiber orientation cases. Although analytical solutions cannot be obtained for real porous substrates because of their random structure, the new theory provides useful insights into the effect of important factors such as fiber orientation, sample porosity, and sample dimensions. The solutions obtained for the model porous media are used to device strategies for more accurate zeta potential determination of porous fiber plugs. The new approach could be thus useful in resolving the long-standing problem of sample geometry dependence of zeta potential measurements.

Analytical methodologies for broad metabolite coverage of exhaled breath condensate.

PubMed

Aksenov, Alexander A; Zamuruyev, Konstantin O; Pasamontes, Alberto; Brown, Joshua F; Schivo, Michael; Foutouhi, Soraya; Weimer, Bart C; Kenyon, Nicholas J; Davis, Cristina E

2017-09-01

Breath analysis has been gaining popularity as a non-invasive technique that is amenable to a broad range of medical uses. One of the persistent problems hampering the wide application of the breath analysis method is measurement variability of metabolite abundances stemming from differences in both sampling and analysis methodologies used in various studies. Mass spectrometry has been a method of choice for comprehensive metabolomic analysis. For the first time in the present study, we juxtapose the most commonly employed mass spectrometry-based analysis methodologies and directly compare the resultant coverages of detected compounds in exhaled breath condensate in order to guide methodology choices for exhaled breath condensate analysis studies. Four methods were explored to broaden the range of measured compounds across both the volatile and non-volatile domain. Liquid phase sampling with polyacrylate Solid-Phase MicroExtraction fiber, liquid phase extraction with a polydimethylsiloxane patch, and headspace sampling using Carboxen/Polydimethylsiloxane Solid-Phase MicroExtraction (SPME) followed by gas chromatography mass spectrometry were tested for the analysis of volatile fraction. Hydrophilic interaction liquid chromatography and reversed-phase chromatography high performance liquid chromatography mass spectrometry were used for analysis of non-volatile fraction. We found that liquid phase breath condensate extraction was notably superior compared to headspace extraction and differences in employed sorbents manifested altered metabolite coverages. The most pronounced effect was substantially enhanced metabolite capture for larger, higher-boiling compounds using polyacrylate SPME liquid phase sampling. The analysis of the non-volatile fraction of breath condensate by hydrophilic and reverse phase high performance liquid chromatography mass spectrometry indicated orthogonal metabolite coverage by these chromatography modes. We found that the metabolite coverage could be enhanced significantly with the use of organic solvent as a device rinse after breath sampling to collect the non-aqueous fraction as opposed to neat breath condensate sample. Here, we show the detected ranges of compounds in each case and provide a practical guide for methodology selection for optimal detection of specific compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Performance-based, cost- and time-effective pcb analytical methodology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alvarado, J. S.

1998-06-11

Laboratory applications for the analysis of PCBs (polychlorinated biphenyls) in environmental matrices such as soil/sediment/sludge and oil/waste oil were evaluated for potential reduction in waste, source reduction, and alternative techniques for final determination. As a consequence, new procedures were studied for solvent substitution, miniaturization of extraction and cleanups, minimization of reagent consumption, reduction of cost per analysis, and reduction of time. These new procedures provide adequate data that meet all the performance requirements for the determination of PCBs. Use of the new procedures reduced costs for all sample preparation techniques. Time and cost were also reduced by combining the newmore » sample preparation procedures with the power of fast gas chromatography. Separation of Aroclor 1254 was achieved in less than 6 min by using DB-1 and SPB-608 columns. With the greatly shortened run times, reproducibility can be tested quickly and consequently with low cost. With performance-based methodology, the applications presented here can be applied now, without waiting for regulatory approval.« less

Determination of polycyclic aromatic hydrocarbons in kerosene and bio-kerosene soot.

PubMed

Andrade-Eiroa, Auréa; Leroy, Valérie; Dagaut, Philippe; Bedjanian, Yuri

2010-03-01

Here we report a new, efficient and reliable analytical methodology for sensitive and selective quantification of Polycyclic Aromatic Hydrocarbons (PAHs) in soot samples. The methodology developed is based on ultrasonic extraction of the soot-bound PAHs into small volumes of acetonitrile, purification of the extracts through C(18) Solid Phase Extraction (SPE) cartridges and analysis by Reverse Phase Liquid Chromatography (RPLC) with UV and fluorimetric detection. For the first time, we report the convenience of adapting the SPE procedure to the nature of the soot samples. As a matter of fact, extracts containing high percentage of unpolar material are recommended to be cleaned with acetone, whereas extracts poor in unpolar compounds can be efficiently cleaned with methanol. The method was satisfactorily applied to kerosene and bio-kerosene soot from atmospheric open diffusion flames (pool fires) and premixed flames achieving Quantification and Detection limits in the range ng mg(-1) soot and recoveries about 90% for most of the PAHs studied. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Strategies to address participant misrepresentation for eligibility in Web-based research.

PubMed

Kramer, Jessica; Rubin, Amy; Coster, Wendy; Helmuth, Eric; Hermos, John; Rosenbloom, David; Moed, Rich; Dooley, Meghan; Kao, Ying-Chia; Liljenquist, Kendra; Brief, Deborah; Enggasser, Justin; Keane, Terence; Roy, Monica; Lachowicz, Mark

2014-03-01

Emerging methodological research suggests that the World Wide Web ("Web") is an appropriate venue for survey data collection, and a promising area for delivering behavioral intervention. However, the use of the Web for research raises concerns regarding sample validity, particularly when the Web is used for recruitment and enrollment. The purpose of this paper is to describe the challenges experienced in two different Web-based studies in which participant misrepresentation threatened sample validity: a survey study and an online intervention study. The lessons learned from these experiences generated three types of strategies researchers can use to reduce the likelihood of participant misrepresentation for eligibility in Web-based research. Examples of procedural/design strategies, technical/software strategies and data analytic strategies are provided along with the methodological strengths and limitations of specific strategies. The discussion includes a series of considerations to guide researchers in the selection of strategies that may be most appropriate given the aims, resources and target population of their studies. Copyright © 2014 John Wiley & Sons, Ltd.

An easy, rapid and inexpensive method to monitor tributyltin (TBT) toxicity in the laboratory.

PubMed

Cruz, Andreia; Moreira, Rafael; Mendo, Sónia

2014-05-01

Tributyltin (TBT) contamination remains a major problem worldwide. Many laboratories are committed to the development of remediation methodologies that could help reduce the negative impact of this compound in the environment. Furthermore, it is important to have at hand simple methodologies for evaluating TBT toxicity in the laboratory, besides the use of complex and costly analytical instrumentation. With that purpose, a method was adapted that is based on the inhibition of growth of an indicator strain, Micrococcus luteus ATCC 9341, under TBT. Different types of matrices, of TBT concentrations and sample treatments were tested. The results herein reported show that the bioassay method can be applied for both aqueous and soil samples and also for a high range of TBT concentrations (at least up to 500 μmol/L). Besides being cheap and easy to perform, it can be performed in any laboratory. Additionally, one possible application of the method to monitor TBT degradation is presented as an example.

Antimony in the environment as a global pollutant: a review on analytical methodologies for its determination in atmospheric aerosols.

PubMed

Smichowski, Patricia

2008-03-15

This review summarizes and discusses the research carried out on the determination of antimony and its predominant chemical species in atmospheric aerosols. Environmental matrices such as airborne particulate matter, fly ash and volcanic ash present a number of complex analytical challenges as very sensitive analytical techniques and highly selective separation methodologies for speciation studies. Given the diversity of instrumental approaches and methodologies employed for the determination of antimony and its species in environmental matrices, the objective of this review is to briefly discuss the most relevant findings reported in the last years for this remarkable element and to identify the future needs and trends. The survey includes 92 references and covers principally the literature published over the last decade.

Analysis of environmental contamination resulting from catastrophic incidents: part 2. Building laboratory capability by selecting and developing analytical methodologies.

PubMed

Magnuson, Matthew; Campisano, Romy; Griggs, John; Fitz-James, Schatzi; Hall, Kathy; Mapp, Latisha; Mullins, Marissa; Nichols, Tonya; Shah, Sanjiv; Silvestri, Erin; Smith, Terry; Willison, Stuart; Ernst, Hiba

2014-11-01

Catastrophic incidents can generate a large number of samples of analytically diverse types, including forensic, clinical, environmental, food, and others. Environmental samples include water, wastewater, soil, air, urban building and infrastructure materials, and surface residue. Such samples may arise not only from contamination from the incident but also from the multitude of activities surrounding the response to the incident, including decontamination. This document summarizes a range of activities to help build laboratory capability in preparation for sample analysis following a catastrophic incident, including selection and development of fit-for-purpose analytical methods for chemical, biological, and radiological contaminants. Fit-for-purpose methods are those which have been selected to meet project specific data quality objectives. For example, methods could be fit for screening contamination in the early phases of investigation of contamination incidents because they are rapid and easily implemented, but those same methods may not be fit for the purpose of remediating the environment to acceptable levels when a more sensitive method is required. While the exact data quality objectives defining fitness-for-purpose can vary with each incident, a governing principle of the method selection and development process for environmental remediation and recovery is based on achieving high throughput while maintaining high quality analytical results. This paper illustrates the result of applying this principle, in the form of a compendium of analytical methods for contaminants of interest. The compendium is based on experience with actual incidents, where appropriate and available. This paper also discusses efforts aimed at adaptation of existing methods to increase fitness-for-purpose and development of innovative methods when necessary. The contaminants of interest are primarily those potentially released through catastrophes resulting from malicious activity. However, the same techniques discussed could also have application to catastrophes resulting from other incidents, such as natural disasters or industrial accidents. Further, the high sample throughput enabled by the techniques discussed could be employed for conventional environmental studies and compliance monitoring, potentially decreasing costs and/or increasing the quantity of data available to decision-makers. Published by Elsevier Ltd.

A Network Method of Measuring Affiliation-based Peer Influence: Assessing the Influences of Teammates’ Smoking on Adolescent Smoking

PubMed Central

Fujimoto, Kayo; Unger, Jennifer B.; Valente, Thomas W.

2011-01-01

Using a network analytic framework, this study introduces a new method to measure peer influence based on adolescents’ affiliations or two-mode social network data. Exposure based on affiliations is referred to as the “affiliation exposure model.” This study demonstrates the methodology using data on young adolescent smoking being influenced by joint participation in school-based organized sports activities with smokers. The analytic sample consisted of 1260 American adolescents from age 10 to 13 in middle schools, and the results of the longitudinal regression analyses showed that adolescents were more likely to smoke as they were increasingly exposed to teammates who smoke. This study illustrates the importance of peer influence via affiliation through team sports. PMID:22313152

Collaborative Visual Analytics: A Health Analytics Approach to Injury Prevention.

PubMed

Al-Hajj, Samar; Fisher, Brian; Smith, Jennifer; Pike, Ian

2017-09-12

Background : Accurate understanding of complex health data is critical in order to deal with wicked health problems and make timely decisions. Wicked problems refer to ill-structured and dynamic problems that combine multidimensional elements, which often preclude the conventional problem solving approach. This pilot study introduces visual analytics (VA) methods to multi-stakeholder decision-making sessions about child injury prevention; Methods : Inspired by the Delphi method, we introduced a novel methodology-group analytics (GA). GA was pilot-tested to evaluate the impact of collaborative visual analytics on facilitating problem solving and supporting decision-making. We conducted two GA sessions. Collected data included stakeholders' observations, audio and video recordings, questionnaires, and follow up interviews. The GA sessions were analyzed using the Joint Activity Theory protocol analysis methods; Results : The GA methodology triggered the emergence of ' common g round ' among stakeholders. This common ground evolved throughout the sessions to enhance stakeholders' verbal and non-verbal communication, as well as coordination of joint activities and ultimately collaboration on problem solving and decision-making; Conclusion s : Understanding complex health data is necessary for informed decisions. Equally important, in this case, is the use of the group analytics methodology to achieve ' common ground' among diverse stakeholders about health data and their implications.

Using design of experiments to optimize derivatization with methyl chloroformate for quantitative analysis of the aqueous phase from hydrothermal liquefaction of biomass.

PubMed

Madsen, René Bjerregaard; Jensen, Mads Mørk; Mørup, Anders Juul; Houlberg, Kasper; Christensen, Per Sigaard; Klemmer, Maika; Becker, Jacob; Iversen, Bo Brummerstedt; Glasius, Marianne

2016-03-01

Hydrothermal liquefaction is a promising technique for the production of bio-oil. The process produces an oil phase, a gas phase, a solid residue, and an aqueous phase. Gas chromatography coupled with mass spectrometry is used to analyze the complex aqueous phase. Especially small organic acids and nitrogen-containing compounds are of interest. The efficient derivatization reagent methyl chloroformate was used to make analysis of the complex aqueous phase from hydrothermal liquefaction of dried distillers grains with solubles possible. A circumscribed central composite design was used to optimize the responses of both derivatized and nonderivatized analytes, which included small organic acids, pyrazines, phenol, and cyclic ketones. Response surface methodology was used to visualize significant factors and identify optimized derivatization conditions (volumes of methyl chloroformate, NaOH solution, methanol, and pyridine). Twenty-nine analytes of small organic acids, pyrazines, phenol, and cyclic ketones were quantified. An additional three analytes were pseudoquantified with use of standards with similar mass spectra. Calibration curves with high correlation coefficients were obtained, in most cases R (2)  > 0.991. Method validation was evaluated with repeatability, and spike recoveries of all 29 analytes were obtained. The 32 analytes were quantified in samples from the commissioning of a continuous flow reactor and in samples from recirculation experiments involving the aqueous phase. The results indicated when the steady-state condition of the flow reactor was obtained and the effects of recirculation. The validated method will be especially useful for investigations of the effect of small organic acids on the hydrothermal liquefaction process.

Development of analytical methodologies to assess recalcitrant pesticide bioremediation in biobeds at laboratory scale.

PubMed

Rivero, Anisleidy; Niell, Silvina; Cerdeiras, M Pía; Heinzen, Horacio; Cesio, María Verónica

2016-06-01

To assess recalcitrant pesticide bioremediation it is necessary to gradually increase the complexity of the biological system used in order to design an effective biobed assembly. Each step towards this effective biobed design needs a suitable, validated analytical methodology that allows a correct evaluation of the dissipation and bioconvertion. Low recovery yielding methods could give a false idea of a successful biodegradation process. To address this situation, different methods were developed and validated for the simultaneous determination of endosulfan, its main three metabolites, and chlorpyrifos in increasingly complex matrices where the bioconvertor basidiomycete Abortiporus biennis could grow. The matrices were culture media, bran, and finally a laboratory biomix composed of bran, peat and soil. The methodology for the analysis of the first evaluated matrix has already been reported. The methodologies developed for the other two systems are presented in this work. The targeted analytes were extracted from fungi growing over bran in semisolid media YNB (Yeast Nitrogen Based) with acetonitrile using shaker assisted extraction, The salting-out step was performed with MgSO4 and NaCl, and the extracts analyzed by GC-ECD. The best methodology was fully validated for all the evaluated analytes at 1 and 25mgkg(-1) yielding recoveries between 72% and 109% and RSDs <11% in all cases. The application of this methodology proved that A. biennis is able to dissipate 94% of endosulfan and 87% of chlorpyrifos after 90 days. Having assessed that A. biennis growing over bran can metabolize the studied pesticides, the next step faced was the development and validation of an analytical procedure to evaluate the analytes in a laboratory scale biobed composed of 50% of bran, 25% of peat and 25% of soil together with fungal micelium. From the different procedures assayed, only ultrasound assisted extraction with ethyl acetate allowed recoveries between 80% and 110% with RSDs <18%. Linearity, recovery, precision, matrix effect and LODs/LOQs of each method were studied for all the analytes: endosulfan isomers (α & β) and its metabolites (endosulfan sulfate, ether and diol) as well as for chlorpyrifos. In the first laboratory evaluation of these biobeds endosulfan was bioconverted up to 87% and chlorpyrifos more than 79% after 27 days. Copyright © 2016 Elsevier B.V. All rights reserved.

How to improve the standardization and the diagnostic performance of the fecal egg count reduction test?

PubMed

Levecke, Bruno; Kaplan, Ray M; Thamsborg, Stig M; Torgerson, Paul R; Vercruysse, Jozef; Dobson, Robert J

2018-04-15

Although various studies have provided novel insights into how to best design, analyze and interpret a fecal egg count reduction test (FECRT), it is still not straightforward to provide guidance that allows improving both the standardization and the analytical performance of the FECRT across a variety of both animal and nematode species. For example, it has been suggested to recommend a minimum number of eggs to be counted under the microscope (not eggs per gram of feces), but we lack the evidence to recommend any number of eggs that would allow a reliable assessment of drug efficacy. Other aspects that need further research are the methodology of calculating uncertainty intervals (UIs; confidence intervals in case of frequentist methods and credible intervals in case of Bayesian methods) and the criteria of classifying drug efficacy into 'normal', 'suspected' and 'reduced'. The aim of this study is to provide complementary insights into the current knowledge, and to ultimately provide guidance in the development of new standardized guidelines for the FECRT. First, data were generated using a simulation in which the 'true' drug efficacy (TDE) was evaluated by the FECRT under varying scenarios of sample size, analytic sensitivity of the diagnostic technique, and level of both intensity and aggregation of egg excretion. Second, the obtained data were analyzed with the aim (i) to verify which classification criteria allow for reliable detection of reduced drug efficacy, (ii) to identify the UI methodology that yields the most reliable assessment of drug efficacy (coverage of TDE) and detection of reduced drug efficacy, and (iii) to determine the required sample size and number of eggs counted under the microscope that optimizes the detection of reduced efficacy. Our results confirm that the currently recommended criteria for classifying drug efficacy are the most appropriate. Additionally, the UI methodologies we tested varied in coverage and ability to detect reduced drug efficacy, thus a combination of UI methodologies is recommended to assess the uncertainty across all scenarios of drug efficacy estimates. Finally, based on our model estimates we were able to determine the required number of eggs to count for each sample size, enabling investigators to optimize the probability of correctly classifying a theoretical TDE while minimizing both financial and technical resources. Copyright © 2018 Elsevier B.V. All rights reserved.

Cork-based activated carbons as supported adsorbent materials for trace level analysis of ibuprofen and clofibric acid in environmental and biological matrices.

PubMed

Neng, N R; Mestre, A S; Carvalho, A P; Nogueira, J M F

2011-09-16

In this contribution, powdered activated carbons (ACs) from cork waste were supported for bar adsorptive micro-extraction (BAμE), as novel adsorbent phases for the analysis of polar compounds. By combining this approach with liquid desorption followed by high performance liquid chromatography with diode array detection (BAμE(AC)-LD/HPLC-DAD), good analytical performance was achieved using clofibric acid (CLOF) and ibuprofen (IBU) model compounds in environmental and biological matrices. Assays performed on 30 mL water samples spiked at the 25.0 μg L(-1) level yielded recoveries around 80% for CLOF and 95% for IBU, under optimized experimental conditions. The ACs textural and surface chemistry properties were correlated with the results obtained. The analytical performance showed good precision (<15%), suitable detection limits (0.24 and 0.78 μg L(-1) for CLOF and IBU, respectively) and good linear dynamic ranges (r(2)>0.9922) from 1.0 to 600.0 μg L(-1). By using the standard addition methodology, the application of the present approach to environmental water and urine matrices allowed remarkable performance at the trace level. The proposed methodology proved to be a viable alternative for acidic pharmaceuticals analysis, showing to be easy to implement, reliable, sensitive and requiring low sample volume to monitor these priority compounds in environmental and biological matrices. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of endocrine disruptor compounds in marine sediments by in cell clean up-pressurized liquid extraction-liquid chromatography tandem mass spectrometry determination.

PubMed

Salgueiro-González, N; Turnes-Carou, I; Muniategui-Lorenzo, S; López-Mahía, P; Prada-Rodríguez, D

2014-12-10

A less time-, solvent- and sorbent-consuming analytical methodology for the determination of bisphenol A and alkylphenols (4-tert-octylphenol, 4-octylphenol, 4-n-nonylphenol, nonylphenol) in marine sediment was developed and validated. The method was based on selective pressurized liquid extraction (SPLE) with a simultaneous in cell clean up combined with liquid chromatography-electrospray ionization tandem mass spectrometry in negative mode (LC-ESI-MS/MS). The SPLE extraction conditions were optimized by a Plackett-Burman design followed by a central composite design. Quantitation was performed by standard addition curves in order to correct matrix effects. The analytical features of the method were satisfactory: relative recoveries varied between 94 and 100% and repeatability and intermediate precision were <6% for all compounds. Uncertainty assessment of measurement was estimated on the basis of an in-house validation according to EURACHEM/CITAC guide. Quantitation limits of the method (MQL) ranged between 0.17 (4-n-nonylphenol) and 4.01 ng g(-1) dry weight (nonylphenol). Sensitivity, selectivity, automaticity and fastness are the main advantages of this green methodology. As an application, marine sediment samples from Galicia coast (NW of Spain) were analysed. Nonylphenol and 4-tert-octylphenol were measured in all samples at concentrations between 20.1 and 1409 ng g(-1) dry weight, respectively. Sediment toxicity was estimated and no risk to aquatic biota was found. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical-mineralogical characterization of C&D waste recycled aggregates from São Paulo, Brazil.

PubMed

Angulo, S C; Ulsen, C; John, V M; Kahn, H; Cincotto, M A

2009-02-01

This study presents a methodology for the characterization of construction and demolition (C&D) waste recycled aggregates based on a combination of analytical techniques (X-ray fluorescence (XRF), soluble ions, semi-quantitative X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTG) and hydrochloric acid (HCl) selective dissolution). These combined analytical techniques allow for the estimation of the amount of cement paste, its most important hydrated and carbonated phases, as well as the amount of clay and micas. Details of the methodology are presented here and the results of three representative C&D samples taken from the São Paulo region in Brazil are discussed. Chemical compositions of mixed C&D aggregate samples have mostly been influenced by particle size rather than the visual classification of C&D into red or grey and geographical origin. The amount of measured soluble salts in C&D aggregates (0.15-25.4mm) is lower than the usual limits for mortar and concrete production. The content of porous cement paste in the C&D aggregates is around 19.3% (w/w). However, this content is significantly lower than the 43% detected for the C&D powders (<0.15 mm). The clay content of the powders was also high, potentially resulting from soil intermixed with the C&D waste, as well as poorly burnt red ceramic. Since only about 50% of the measured CaO is combined with CO(2), the powders have potential use as raw materials for the cement industry.

Statistical methodology for estimating the mean difference in a meta-analysis without study-specific variance information.

PubMed

Sangnawakij, Patarawan; Böhning, Dankmar; Adams, Stephen; Stanton, Michael; Holling, Heinz

2017-04-30

Statistical inference for analyzing the results from several independent studies on the same quantity of interest has been investigated frequently in recent decades. Typically, any meta-analytic inference requires that the quantity of interest is available from each study together with an estimate of its variability. The current work is motivated by a meta-analysis on comparing two treatments (thoracoscopic and open) of congenital lung malformations in young children. Quantities of interest include continuous end-points such as length of operation or number of chest tube days. As studies only report mean values (and no standard errors or confidence intervals), the question arises how meta-analytic inference can be developed. We suggest two methods to estimate study-specific variances in such a meta-analysis, where only sample means and sample sizes are available in the treatment arms. A general likelihood ratio test is derived for testing equality of variances in two groups. By means of simulation studies, the bias and estimated standard error of the overall mean difference from both methodologies are evaluated and compared with two existing approaches: complete study analysis only and partial variance information. The performance of the test is evaluated in terms of type I error. Additionally, we illustrate these methods in the meta-analysis on comparing thoracoscopic and open surgery for congenital lung malformations and in a meta-analysis on the change in renal function after kidney donation. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Headspace-Solid-Phase Microextraction-Gas Chromatography as Analytical Methodology for the Determination of Volatiles in Wild Mushrooms and Evaluation of Modifications Occurring during Storage

PubMed Central

Costa, Rosaria; De Grazia, Selenia; Grasso, Elisa; Trozzi, Alessandra

2015-01-01

Mushrooms are sources of food, medicines, and agricultural means. Not much is reported in the literature about wild species of the Mediterranean flora, although many of them are traditionally collected for human consumption. The knowledge of their chemical constituents could represent a valid tool for both taxonomic and physiological characterizations. In this work, a headspace-solid-phase microextraction (HS-SPME) method coupled with GC-MS and GC-FID was developed to evaluate the volatile profiles of ten wild mushroom species collected in South Italy. In addition, in order to evaluate the potential of this analytical methodology for true quantitation of volatiles, samples of the cultivated species Agaricus bisporus were analyzed. The choice of this mushroom was dictated by its ease of availability in the food market, due to the consistent amounts required for SPME method development. For calibration of the main volatile compounds, the standard addition method was chosen. Finally, the assessed volatile composition of A. bisporus was monitored in order to evaluate compositional changes occurring during storage, which represents a relevant issue for such a wide consumption edible product. PMID:25945282

HS-SPME determination of volatile carbonyl and carboxylic compounds in different matrices.

PubMed

Stashenko, Elena E; Mora, Amanda L; Cervantes, Martha E; Martínez, Jairo R

2006-07-01

Specific chromatographic methodologies are developed for the analysis of carboxylic acids (C(2)-C(6), benzoic) and aldehydes (C(2)-C(10)) of low molecular weight in diverse matrices, such as air, automotive exhaust gases, human breath, and aqueous matrices. For carboxylic acids, the method is based on their reaction with pentafluorobenzyl bromide in aqueous solution, followed by the separation and identification of the resultant pentafluorobenzyl esters by means of headspace (HS)-solid-phase microextraction (SPME) combined with gas chromatography (GC) and electron capture detection (ECD). Detection limits in the microg/m(3) range are reached, with relative standard deviation (RSD) less than 10% and linear response (R(2) > 0.99) over two orders of magnitude. The analytical methodology for aldehydes is based on SPME with simultaneous derivatization of the analytes on the fiber, by reaction with pentafluorophenylhydrazine. The derivatization reagent is previously deposited on the SPME fiber, which is then exposed to the gaseous matrix or the HS of the sample solution. The pentafluorophenyl hydrazones formed on the fiber are analyzed selectively by means of GC-ECD, with detection limits in the ng/m(3) range, RSD less than 10%, and linear response (R(2) > 0.99) over two orders of magnitude.

Mycotoxin Analysis of Human Urine by LC-MS/MS: A Comparative Extraction Study

PubMed Central

Escrivá, Laura; Font, Guillermina

2017-01-01

The lower mycotoxin levels detected in urine make the development of sensitive and accurate analytical methods essential. Three extraction methods, namely salting-out liquid–liquid extraction (SALLE), miniQuEChERS (quick, easy, cheap, effective, rugged, and safe), and dispersive liquid–liquid microextraction (DLLME), were evaluated and compared based on analytical parameters for the quantitative LC-MS/MS measurement of 11 mycotoxins (AFB1, AFB2, AFG1, AFG2, OTA, ZEA, BEA, EN A, EN B, EN A1 and EN B1) in human urine. DLLME was selected as the most appropriate methodology, as it produced better validation results for recovery (79–113%), reproducibility (RSDs < 12%), and repeatability (RSDs < 15%) than miniQuEChERS (71–109%, RSDs <14% and <24%, respectively) and SALLE (70–108%, RSDs < 14% and < 24%, respectively). Moreover, the lowest detection (LODS) and quantitation limits (LOQS) were achieved with DLLME (LODs: 0.005–2 μg L−1, LOQs: 0.1–4 μg L−1). DLLME methodology was used for the analysis of 10 real urine samples from healthy volunteers showing the presence of ENs B, B1 and A1 at low concentrations. PMID:29048356

Methodological evaluation and comparison of five urinary albumin measurements.

PubMed

Liu, Rui; Li, Gang; Cui, Xiao-Fan; Zhang, Dong-Ling; Yang, Qing-Hong; Mu, Xiao-Yan; Pan, Wen-Jie

2011-01-01

Microalbuminuria is an indicator of kidney damage and a risk factor for the progression kidney disease, cardiovascular disease, and so on. Therefore, accurate and precise measurement of urinary albumin is critical. However, there are no reference measurement procedures and reference materials for urinary albumin. Nephelometry, turbidimetry, colloidal gold method, radioimmunoassay, and chemiluminescence immunoassay were performed for methodological evaluation, based on imprecision test, recovery rate, linearity, haemoglobin interference rate, and verified reference interval. Then we tested 40 urine samples from diabetic patients by each method, and compared the result between assays. The results indicate that nephelometry is the method with best analytical performance among the five methods, with an average intraassay coefficient of variation (CV) of 2.6%, an average interassay CV of 1.7%, a mean recovery of 99.6%, a linearity of R=1.00 from 2 to 250 mg/l, and an interference rate of <10% at haemoglobin concentrations of <1.82 g/l. The correlation (r) between assays was from 0.701 to 0.982, and the Bland-Altman plots indicated each assay provided significantly different results from each other. Nephelometry is the clinical urinary albumin method with best analytical performance in our study. © 2011 Wiley-Liss, Inc.

Selective trace enrichment of chlorotriazine pesticides from natural waters and sediment samples using terbuthylazine molecularly imprinted polymers

USGS Publications Warehouse

Ferrer, I.; Lanza, F.; Tolokan, A.; Horvath, V.; Sellergren, B.; Horvai, G.; Barcelo, D.

2000-01-01

Two molecularly imprinted polymers were synthesized using either dichloromethane or toluene as the porogen and terbuthylazine as the template and were used as solid-phase extraction cartridges for the enrichment of six chlorotriazines (deisopropylatrazine, deethylatrazine, simazine, atrazine, propazine, and terbuthylazine) in natural water and sediment samples. The extracted samples were analyzed by liquid chromatography/diode array detection (LC/DAD). Several washing solvents, as well as different volumes, were tested for their ability to remove the matrix components nonspecifically adsorbed on the sorbents. This cleanup step was shown to be of prime importance to the successful extraction of the pesticides from the aqueous samples. The optimal analytical conditions were obtained when the MIP imprinted using dichloromethane was the sorbent, 2 mL of dichloromethane was used in the washing step, and the preconcentrated analytes were eluted with 8 mL of methanol. The recoveries were higher than 80% for all the chlorotriazines except for propazine (53%) when 50- or 100-mL groundwater samples, spiked at 1 ??g/L level, were analyzed. The limits of detection varied from 0.05 to 0.2 ??g/L when preconcentrating a 100-mL groundwater sample. Natural sediment samples from the Ebre Delta area (Tarragona, Spain) containing atrazine and deethylatrazine were Soxhlet extracted and analyzed by the methodology developed in this work. No significant interferences from the sample matrix were noticed, thus indicating good selectivity of the MIP sorbents used.

An analytical procedure to assist decision-making in a government research organization

Treesearch

H. Dean Claxton; Giuseppe Rensi

1972-01-01

An analytical procedure to help management decision-making in planning government research is described. The objectives, activities, and restrictions of a government research organization are modeled in a consistent analytical framework. Theory and methodology is drawn from economics and mathe-matical programing. The major analytical aspects distinguishing research...

Analytical and simulator study of advanced transport

NASA Technical Reports Server (NTRS)

Levison, W. H.; Rickard, W. W.

1982-01-01

An analytic methodology, based on the optimal-control pilot model, was demonstrated for assessing longitidunal-axis handling qualities of transport aircraft in final approach. Calibration of the methodology is largely in terms of closed-loop performance requirements, rather than specific vehicle response characteristics, and is based on a combination of published criteria, pilot preferences, physical limitations, and engineering judgment. Six longitudinal-axis approach configurations were studied covering a range of handling qualities problems, including the presence of flexible aircraft modes. The analytical procedure was used to obtain predictions of Cooper-Harper ratings, a solar quadratic performance index, and rms excursions of important system variables.

LOX/hydrocarbon rocket engine analytical design methodology development and validation. Volume 1: Executive summary and technical narrative

NASA Technical Reports Server (NTRS)

Pieper, Jerry L.; Walker, Richard E.

1993-01-01

During the past three decades, an enormous amount of resources were expended in the design and development of Liquid Oxygen/Hydrocarbon and Hydrogen (LOX/HC and LOX/H2) rocket engines. A significant portion of these resources were used to develop and demonstrate the performance and combustion stability for each new engine. During these efforts, many analytical and empirical models were developed that characterize design parameters and combustion processes that influence performance and stability. Many of these models are suitable as design tools, but they have not been assembled into an industry-wide usable analytical design methodology. The objective of this program was to assemble existing performance and combustion stability models into a usable methodology capable of producing high performing and stable LOX/hydrocarbon and LOX/hydrogen propellant booster engines.

Application of person-centered analytic methodology in longitudinal research: exemplars from the Women's Health Initiative Clinical Trial data.

PubMed

Zaslavsky, Oleg; Cochrane, Barbara B; Herting, Jerald R; Thompson, Hilaire J; Woods, Nancy F; Lacroix, Andrea

2014-02-01

Despite the variety of available analytic methods, longitudinal research in nursing has been dominated by use of a variable-centered analytic approach. The purpose of this article is to present the utility of person-centered methodology using a large cohort of American women 65 and older enrolled in the Women's Health Initiative Clinical Trial (N = 19,891). Four distinct trajectories of energy/fatigue scores were identified. Levels of fatigue were closely linked to age, socio-demographic factors, comorbidities, health behaviors, and poor sleep quality. These findings were consistent regardless of the methodological framework. Finally, we demonstrated that energy/fatigue levels predicted future hospitalization in non-disabled elderly. Person-centered methods provide unique opportunities to explore and statistically model the effects of longitudinal heterogeneity within a population. © 2013 Wiley Periodicals, Inc.

Sample preparation and EFTEM of Meat Samples for Nanoparticle Analysis in Food

NASA Astrophysics Data System (ADS)

Lari, L.; Dudkiewicz, A.

2014-06-01

Nanoparticles are used in industry for personal care products and the preparation of food. In the latter application, their functions include the prevention of microbes' growth, increase of the foods nutritional value and sensory quality. EU regulations require a risk assessment of the nanoparticles used in foods and food contact materials before the products can reach the market. However, availability of validated analytical methodologies for detection and characterisation of the nanoparticles in food hampers appropriate risk assessment. As part of a research on the evaluation of the methods for screening and quantification of Ag nanoparticles in meat we have tested a new TEM sample preparation alternative to resin embedding and cryo-sectioning. Energy filtered TEM analysis was applied to evaluate thickness and the uniformity of thin meat layers acquired at increasing input of the sample demonstrating that the protocols used ensured good stability under the electron beam, reliable sample concentration and reproducibility.

Electrokinetic supercharging with a system-induced terminator and an optimized capillary versus electrode configuration for parts-per-trillion detection of rare-earth elements in CZE.

PubMed

Xu, Zhongqi; Kawahito, Kouji; Ye, Xiaoxue; Timerbaev, Andrei R; Hirokawa, Takeshi

2011-05-01

A further improvement of electrokinetic supercharging (EKS) methodology has been proposed, with the objective to enhance the sensitivity of the conventional CZE-UV method down to a single-digit part per trillion (ppt) level. The advanced EKS procedure is based on a novel phenomenon displaying the formation of a zone with an increased concentration of the hydrogen ion, capable to perform the function of a terminator, behind the sample zone upon electrokinetic injection. In combination with a visualizing co-ion of BGE, protonated 4-methylbenzylamine, acting as the leading ion, such system-induced terminator a effected the transient ITP state to efficiently concentrate cationic analytes prior to CZE. Furthermore, to amass more analyte ions within the effective electric field at the injection stage, a standard sample vial was replaced with an elongated vial that allowed the sample volume to be increased from 500 to 900 μL. Alongside, this replacement made the upright distance between the electrode and the capillary tips prolonged to 40.0 mm to achieve high-efficiency electrokinetic injection. The computer simulation was used for profiling analyte concentration, pH, and field strength in order to delineate formation of the terminator during sample injection. The proposed preconcentration strategy afforded an enrichment factor of 80,000 and thereby the LODs of rare-earth metal ions at the ppt level, e.g. 0.04 nM (6.7 ng/L) for erbium(III). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of endocrine disrupting compounds and their metabolites in fish bile.

PubMed

Ros, Oihana; Izaguirre, Jon Kepa; Olivares, Maitane; Bizarro, Cristina; Ortiz-Zarragoitia, Maren; Cajaraville, Miren Pilar; Etxebarria, Nestor; Prieto, Ailette; Vallejo, Asier

2015-12-01

This work describes a new methodology for the simultaneous determination of a large variety of emerging and persistent organic compounds and some of their metabolites in fish bile samples. The target compounds were musk fragrances, alkyl phenols, hormones, pesticides, phthalate esters and bisphenol-A, all of them with a known endocrine disrupting effect. To achieve the determination these three steps were optimized: i) an enzymatic hydrolysis of the metabolites to render the unconjugated compounds; ii) the solid phase extraction of the target analytes (Plexa cartridges 200-mg); and, iii) a clean-up of the extracts (Florisil cartridges 1-g). The samples were analyzed by gas-chromatography-mass spectrometry (GC-MS), though the polar fraction required a previous derivatization with O-bis (trimethylsilyl) trifluoroacetamide. Good apparent recoveries (63-122%), repeatability (<20%) and limits of detection (LODs) ranging between 0.04 and 459 ng/mL were obtained. This method was applied to the analysis of the target analytes in bile samples of thicklip grey mullets (Chelon labrosus) from five different populations of the Basque Coast (South East Bay of Biscay) during the period of May-June 2012. The target analytes were found at concentrations ranging from

Mind the gaps - the epidemiology of poor-quality anti-malarials in the malarious world - analysis of the WorldWide Antimalarial Resistance Network database

PubMed Central

2014-01-01

Background Poor quality medicines threaten the lives of millions of patients and are alarmingly common in many parts of the world. Nevertheless, the global extent of the problem remains unknown. Accurate estimates of the epidemiology of poor quality medicines are sparse and are influenced by sampling methodology and diverse chemical analysis techniques. In order to understand the existing data, the Antimalarial Quality Scientific Group at WWARN built a comprehensive, open-access, global database and linked Antimalarial Quality Surveyor, an online visualization tool. Analysis of the database is described here, the limitations of the studies and data reported, and their public health implications discussed. Methods The database collates customized summaries of 251 published anti-malarial quality reports in English, French and Spanish by time and location since 1946. It also includes information on assays to determine quality, sampling and medicine regulation. Results No publicly available reports for 60.6% (63) of the 104 malaria-endemic countries were found. Out of 9,348 anti-malarials sampled, 30.1% (2,813) failed chemical/packaging quality tests with 39.3% classified as falsified, 2.3% as substandard and 58.3% as poor quality without evidence available to categorize them as either substandard or falsified. Only 32.3% of the reports explicitly described their definitions of medicine quality and just 9.1% (855) of the samples collected in 4.6% (six) surveys were conducted using random sampling techniques. Packaging analysis was only described in 21.5% of publications and up to twenty wrong active ingredients were found in falsified anti-malarials. Conclusions There are severe neglected problems with anti-malarial quality but there are important caveats to accurately estimate the prevalence and distribution of poor quality anti-malarials. The lack of reports in many malaria-endemic areas, inadequate sampling techniques and inadequate chemical analytical methods and instrumental procedures emphasizes the need to interpret medicine quality results with caution. The available evidence demonstrates the need for more investment to improve both sampling and analytical methodology and to achieve consensus in defining different types of poor quality medicines. PMID:24712972

Human dermal exposure to galaxolide from personal care products.

PubMed

Correia, P; Cruz, A; Santos, L; Alves, A

2013-06-01

Musks are synthetic fragrances applied on personal care and household products as fixatives, by retarding the release of other fragrances with higher volatility. Galaxolide is the most used polycyclic musk since the 90th decade, and it has been detected in several environmental and biological matrices, particularly in human tissues and fluids. For exposure assessment purposes, large-monitoring data need to be obtained and rapid but reliable analytical techniques are requested. The main objective of this study is to develop and validate a new and fast analytical methodology to quantify galaxolide in personal care products and to apply this method to real matrices like skin care products (creams and lotions), shower products (soap bar), hair care products (shampoo and hair conditioner) and oral care products (toothpaste), to evaluate the human dermal exposure risk. A dispersive solid-phase extraction is proposed, using QuEChERS methodology, followed by HPLC with fluorescence detection. Some extraction parameters were studied, like the ratio of sample/solvent amounts, the homogenization time, the salt addition effect and the used sorbents. The validation parameters of the developed method were the following: a linearity range of 0.005-1.002 mg kg⁻¹ sample, a limit of detection of 0.001 mg kg⁻¹ sample, repeatability between 0.7% and 11.3% (variation coefficient of six standard injections), an intermediate precision of 2.5% (variation coefficient of six independent analysis of the same sample), mean recoveries ranging from 65% (soap bar) to 95% (body cream) and 3% of global uncertainty in most of the working range. The time of analysis, including the extraction steps, is 60 min, allowing a throughput of 4 samples h⁻¹ . Galaxolide was detected in all of the seven analysed products in concentrations ranging from 0.04 ± 0.01 mg kg⁻¹ sample (toothpaste) to 280.78 ± 8.19 mg kg⁻¹ sample (perfumed body cream), which may correspond to a significant estimated daily human dermal exposure of 904 μg day⁻¹. © 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Investigation of pharmaceuticals in processed animal by-products by liquid chromatography coupled to high-resolution mass spectrometry.

PubMed

Nácher-Mestre, Jaime; Ibáñez, María; Serrano, Roque; Boix, Clara; Bijlsma, Lubertus; Lunestad, Bjørn Tore; Hannisdal, Rita; Alm, Martin; Hernández, Félix; Berntssen, Marc H G

2016-07-01

There is an on-going trend for developing more sustainable salmon feed in which traditionally applied marine feed ingredients are replaced with alternatives. Processed animal products (PAPs) have been re-authorized as novel high quality protein ingredients in 2013. These PAPs may harbor undesirable substances such as pharmaceuticals and metabolites which are not previously associated with salmon farming, but might cause a potential risk for feed and food safety. To control these contaminants, an analytical strategy based on a generic extraction followed by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS) using quadrupole time-of-flight mass analyzer (QTOF MS) was applied for wide scope screening. Quality control samples, consisting of PAP commodities spiked at 0.02, 0.1 and 0.2 mg/kg with 150 analytes, were injected in every sample batch to verify the overall method performance. The methodology was applied to 19 commercially available PAP samples from six different types of matrices from the EU animal rendering industry. This strategy allows assessing possible emergent risk exposition of the salmon farming industry to 1005 undesirables, including pharmaceuticals, several dyes and relevant metabolites. Copyright © 2016 Elsevier Ltd. All rights reserved.

On estimation of linear transformation models with nested case–control sampling

PubMed Central

Liu, Mengling

2011-01-01

Nested case–control (NCC) sampling is widely used in large epidemiological cohort studies for its cost effectiveness, but its data analysis primarily relies on the Cox proportional hazards model. In this paper, we consider a family of linear transformation models for analyzing NCC data and propose an inverse selection probability weighted estimating equation method for inference. Consistency and asymptotic normality of our estimators for regression coefficients are established. We show that the asymptotic variance has a closed analytic form and can be easily estimated. Numerical studies are conducted to support the theory and an application to the Wilms’ Tumor Study is also given to illustrate the methodology. PMID:21912975

High-Precision In Situ 87Sr/86Sr Analyses through Microsampling on Solid Samples: Applications to Earth and Life Sciences

PubMed Central

Di Salvo, Sara; Casalini, Martina; Marchionni, Sara; Adani, Teresa; Ulivi, Maurizio; Tommasini, Simone; Avanzinelli, Riccardo; Mazza, Paul P. A.; Francalanci, Lorella

2018-01-01

An analytical protocol for high-precision, in situ microscale isotopic investigations is presented here, which combines the use of a high-performing mechanical microsampling device and high-precision TIMS measurements on micro-Sr samples, allowing for excellent results both in accuracy and precision. The present paper is a detailed methodological description of the whole analytical procedure from sampling to elemental purification and Sr-isotope measurements. The method offers the potential to attain isotope data at the microscale on a wide range of solid materials with the use of minimally invasive sampling. In addition, we present three significant case studies for geological and life sciences, as examples of the various applications of microscale 87Sr/86Sr isotope ratios, concerning (i) the pre-eruptive mechanisms triggering recent eruptions at Nisyros volcano (Greece), (ii) the dynamics involved with the initial magma ascent during Eyjafjallajökull volcano's (Iceland) 2010 eruption, which are usually related to the precursory signals of the eruption, and (iii) the environmental context of a MIS 3 cave bear, Ursus spelaeus. The studied cases show the robustness of the methods, which can be also be applied in other areas, such as cultural heritage, archaeology, petrology, and forensic sciences. PMID:29850369

Miniaturizing and automation of free acidity measurements for uranium (VI)-HNO3 solutions: Development of a new sequential injection analysis for a sustainable radio-analytical chemistry.

PubMed

Néri-Quiroz, José; Canto, Fabrice; Guillerme, Laurent; Couston, Laurent; Magnaldo, Alastair; Dugas, Vincent

2016-10-01

A miniaturized and automated approach for the determination of free acidity in solutions containing uranium (VI) is presented. The measurement technique is based on the concept of sequential injection analysis with on-line spectroscopic detection. The proposed methodology relies on the complexation and alkalimetric titration of nitric acid using a pH 5.6 sodium oxalate solution. The titration process is followed by UV/VIS detection at 650nm thanks to addition of Congo red as universal pH indicator. Mixing sequence as well as method validity was investigated by numerical simulation. This new analytical design allows fast (2.3min), reliable and accurate free acidity determination of low volume samples (10µL) containing uranium/[H(+)] moles ratio of 1:3 with relative standard deviation of <7.0% (n=11). The linearity range of the free nitric acid measurement is excellent up to 2.77molL(-1) with a correlation coefficient (R(2)) of 0.995. The method is specific, presence of actinide ions up to 0.54molL(-1) does not interfere on the determination of free nitric acid. In addition to automation, the developed sequential injection analysis method greatly improves the standard off-line oxalate complexation and alkalimetric titration method by reducing thousand fold the required sample volume, forty times the nuclear waste per analysis as well as the analysis time by eight fold. These analytical parameters are important especially in nuclear-related applications to improve laboratory safety, personnel exposure to radioactive samples and to drastically reduce environmental impacts or analytical radioactive waste. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect on cadaver blood DNA identification by the use of targeted and whole body post-mortem computed tomography angiography.

PubMed

Rutty, Guy N; Barber, Jade; Amoroso, Jasmin; Morgan, Bruno; Graham, Eleanor A M

2013-12-01

Post-mortem computed tomography angiography (PMCTA) involves the injection of contrast agents. This could have both a dilution effect on biological fluid samples and could affect subsequent post-contrast analytical laboratory processes. We undertook a small sample study of 10 targeted and 10 whole body PMCTA cases to consider whether or not these two methods of PMCTA could affect post-PMCTA cadaver blood based DNA identification. We used standard methodology to examine DNA from blood samples obtained before and after the PMCTA procedure. We illustrate that neither of these PMCTA methods had an effect on the alleles called following short tandem repeat based DNA profiling, and therefore the ability to undertake post-PMCTA blood based DNA identification.

Guidelines for reporting methodological challenges and evaluating potential bias in dementia research

PubMed Central

Weuve, Jennifer; Proust-Lima, Cécile; Power, Melinda C.; Gross, Alden L.; Hofer, Scott M.; Thiébaut, Rodolphe; Chêne, Geneviève; Glymour, M. Maria; Dufouil, Carole

2015-01-01

Clinical and population research on dementia and related neurologic conditions, including Alzheimer’s disease, faces several unique methodological challenges. Progress to identify preventive and therapeutic strategies rests on valid and rigorous analytic approaches, but the research literature reflects little consensus on “best practices.” We present findings from a large scientific working group on research methods for clinical and population studies of dementia, which identified five categories of methodological challenges as follows: (1) attrition/sample selection, including selective survival; (2) measurement, including uncertainty in diagnostic criteria, measurement error in neuropsychological assessments, and practice or retest effects; (3) specification of longitudinal models when participants are followed for months, years, or even decades; (4) time-varying measurements; and (5) high-dimensional data. We explain why each challenge is important in dementia research and how it could compromise the translation of research findings into effective prevention or care strategies. We advance a checklist of potential sources of bias that should be routinely addressed when reporting dementia research. PMID:26397878

The temporal structure of pollution levels in developed cities.

PubMed

Barrigón Morillas, Juan Miguel; Ortiz-Caraballo, Carmen; Prieto Gajardo, Carlos

2015-06-01

Currently, the need for mobility can cause significant pollution levels in cities, with important effects on health and quality of life. Any approach to the study of urban pollution and its effects requires an analysis of spatial distribution and temporal variability. It is a crucial dilemma to obtain proven methodologies that allow an increase in the quality of the prediction and the saving of resources in the spatial and temporal sampling. This work proposes a new analytical methodology in the study of temporal structure. As a result, a model for estimating annual levels of urban traffic noise was proposed. The average errors are less than one decibel in all acoustics indicators. A new working methodology of urban noise has begun. Additionally, a general application can be found for the study of the impacts of pollution associated with traffic, with implications for urban design and possibly in economic and sociological aspects. Copyright © 2015 Elsevier B.V. All rights reserved.

Fast methodology of analysing major steviol glycosides from Stevia rebaudiana leaves.

PubMed

Lorenzo, Cándida; Serrano-Díaz, Jéssica; Plaza, Miguel; Quintanilla, Carmen; Alonso, Gonzalo L

2014-08-15

The aim of this work is to propose an HPLC method for analysing major steviol glycosides as well as to optimise the extraction and clarification conditions for obtaining these compounds. Toward this aim, standards of stevioside and rebaudioside A with purities ⩾99.0%, commercial samples from different companies and Stevia rebaudiana Bertoni leaves from Paraguay supplied by Insobol, S.L., were used. The analytical method proposed is adequate in terms of selectivity, sensitivity and accuracy. Optimum extraction conditions and adequate clarification conditions have been set. Moreover, this methodology is safe and eco-friendly, as we use only water for extraction and do not use solid-phase extraction, which requires solvents that are banned in the food industry to condition the cartridge and elute the steviol glycosides. In addition, this methodology consumes little time as leaves are not ground and the filtration is faster, and the peak resolution is better as we used an HPLC method with gradient elution. Copyright © 2014 Elsevier Ltd. All rights reserved.

Estimation of the limit of detection using information theory measures.

PubMed

Fonollosa, Jordi; Vergara, Alexander; Huerta, Ramón; Marco, Santiago

2014-01-31

Definitions of the limit of detection (LOD) based on the probability of false positive and/or false negative errors have been proposed over the past years. Although such definitions are straightforward and valid for any kind of analytical system, proposed methodologies to estimate the LOD are usually simplified to signals with Gaussian noise. Additionally, there is a general misconception that two systems with the same LOD provide the same amount of information on the source regardless of the prior probability of presenting a blank/analyte sample. Based upon an analogy between an analytical system and a binary communication channel, in this paper we show that the amount of information that can be extracted from an analytical system depends on the probability of presenting the two different possible states. We propose a new definition of LOD utilizing information theory tools that deals with noise of any kind and allows the introduction of prior knowledge easily. Unlike most traditional LOD estimation approaches, the proposed definition is based on the amount of information that the chemical instrumentation system provides on the chemical information source. Our findings indicate that the benchmark of analytical systems based on the ability to provide information about the presence/absence of the analyte (our proposed approach) is a more general and proper framework, while converging to the usual values when dealing with Gaussian noise. Copyright © 2013 Elsevier B.V. All rights reserved.

SociAL Sensor Analytics: Measuring Phenomenology at Scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corley, Courtney D.; Dowling, Chase P.; Rose, Stuart J.

The objective of this paper is to present a system for interrogating immense social media streams through analytical methodologies that characterize topics and events critical to tactical and strategic planning. First, we propose a conceptual framework for interpreting social media as a sensor network. Time-series models and topic clustering algorithms are used to implement this concept into a functioning analytical system. Next, we address two scientific challenges: 1) to understand, quantify, and baseline phenomenology of social media at scale, and 2) to develop analytical methodologies to detect and investigate events of interest. This paper then documents computational methods and reportsmore » experimental findings that address these challenges. Ultimately, the ability to process billions of social media posts per week over a period of years enables the identification of patterns and predictors of tactical and strategic concerns at an unprecedented rate through SociAL Sensor Analytics (SALSA).« less

7 CFR 91.23 - Analytical methods.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 3 2014-01-01 2014-01-01 false Analytical methods. 91.23 Section 91.23 Agriculture... SERVICES AND GENERAL INFORMATION Method Manuals § 91.23 Analytical methods. Most analyses are performed according to approved procedures described in manuals of standardized methodology. These standard methods...

7 CFR 91.23 - Analytical methods.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 3 2011-01-01 2011-01-01 false Analytical methods. 91.23 Section 91.23 Agriculture... SERVICES AND GENERAL INFORMATION Method Manuals § 91.23 Analytical methods. Most analyses are performed according to approved procedures described in manuals of standardized methodology. These standard methods...

7 CFR 91.23 - Analytical methods.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 3 2013-01-01 2013-01-01 false Analytical methods. 91.23 Section 91.23 Agriculture... SERVICES AND GENERAL INFORMATION Method Manuals § 91.23 Analytical methods. Most analyses are performed according to approved procedures described in manuals of standardized methodology. These standard methods...

Analytical Chemistry Division annual progress report for period ending November 30, 1977

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyon, W.S.

1978-03-01

Activities for the year are summarized in sections on analytical methodology, mass and mass emission spectrometry, analytical services, bio-organic analysis, nuclear and radiochemical analysis, and quality assurance and safety. Presentations of research results in publications and reports are tabulated. (JRD)

A stepwise, 'test-all-positives' methodology to assess gluten-kernel contamination at the serving-size level in gluten-free (GF) oat production.

PubMed

Chen, Yumin; Fritz, Ronald D; Kock, Lindsay; Garg, Dinesh; Davis, R Mark; Kasturi, Prabhakar

2018-02-01

A step-wise, 'test-all-positive-gluten' analytical methodology has been developed and verified to assess kernel-based gluten contamination (i.e., wheat, barley and rye kernels) during gluten-free (GF) oat production. It targets GF claim compliance at the serving-size level (of a pouch or approximately 40-50g). Oat groats are collected from GF oat production following a robust attribute-based sampling plan then split into 75-g subsamples, and ground. R-Biopharm R5 sandwich ELISA R7001 is used for analysis of all the first15-g portions of the ground sample. A >20-ppm result disqualifies the production lot, while a >5 to <20-ppm result triggers complete analysis of the remaining 60-g of ground sample, analyzed in 15-g portions. If all five 15-g test results are <20ppm, and their average is <10.67ppm (since a 20-ppm contaminant in 40g of oats would dilute to 10.67ppm in 75-g), the lot is passed. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Novel analytical methods to assess the chemical and physical properties of liposomes.

PubMed

Kothalawala, Nuwan; Mudalige, Thilak K; Sisco, Patrick; Linder, Sean W

2018-08-01

Liposomes are used in commercial pharmaceutical formulations (PFs) and dietary supplements (DSs) as a carrier vehicle to protect the active ingredient from degradation and to increase the half-life of the injectable. Even as the commercialization of liposomal products has rapidly increased, characterization methodologies to evaluate physical and chemical properties of the liposomal products have not been well-established. Herein we develop rapid methodologies to evaluate chemical and selected physical properties of liposomal formulations. Chemical properties of liposomes are determined by their lipid composition. The lipid composition is evaluated by first screening of the lipids present in the sample using HPLC-ELSD followed by HPLC-MSMS analysis with high mass accuracy (<5 ppm), fragmentation pattern and lipid structure databases searching. Physical properties such as particle size and size distribution were investigated using Tunable Resistive Pulse Sensing (TRPS). The developed methods were used to analyze commercially available PFs and DSs. As results, PFs contain distinct number of lipids as indicated by the manufacture, but DSs were more complicated containing a large number of lipids belonging to different sub-classes. Commercially available liposomes have particles with wide size distribution based on size measurements performed by TRPS. The high mass accuracy as well as identification lipids using multiple fragment ions aided to accurately identify the lipids and differentiate them from other lipophilic molecules. The developed analytical methodologies were successfully adapted to measure the physiochemical properties of commercial liposomes. Copyright © 2018. Published by Elsevier B.V.

Analytical robustness of quantitative NIR chemical imaging for Islamic paper characterization

NASA Astrophysics Data System (ADS)

Mahgoub, Hend; Gilchrist, John R.; Fearn, Thomas; Strlič, Matija

2017-07-01

Recently, spectral imaging techniques such as Multispectral (MSI) and Hyperspectral Imaging (HSI) have gained importance in the field of heritage conservation. This paper explores the analytical robustness of quantitative chemical imaging for Islamic paper characterization by focusing on the effect of different measurement and processing parameters, i.e. acquisition conditions and calibration on the accuracy of the collected spectral data. This will provide a better understanding of the technique that can provide a measure of change in collections through imaging. For the quantitative model, special calibration target was devised using 105 samples from a well-characterized reference Islamic paper collection. Two material properties were of interest: starch sizing and cellulose degree of polymerization (DP). Multivariate data analysis methods were used to develop discrimination and regression models which were used as an evaluation methodology for the metrology of quantitative NIR chemical imaging. Spectral data were collected using a pushbroom HSI scanner (Gilden Photonics Ltd) in the 1000-2500 nm range with a spectral resolution of 6.3 nm using a mirror scanning setup and halogen illumination. Data were acquired at different measurement conditions and acquisition parameters. Preliminary results showed the potential of the evaluation methodology to show that measurement parameters such as the use of different lenses and different scanning backgrounds may not have a great influence on the quantitative results. Moreover, the evaluation methodology allowed for the selection of the best pre-treatment method to be applied to the data.

Diffusion orientation transform revisited.

PubMed

Canales-Rodríguez, Erick Jorge; Lin, Ching-Po; Iturria-Medina, Yasser; Yeh, Chun-Hung; Cho, Kuan-Hung; Melie-García, Lester

2010-01-15

Diffusion orientation transform (DOT) is a powerful imaging technique that allows the reconstruction of the microgeometry of fibrous tissues based on diffusion MRI data. The three main error sources involving this methodology are the finite sampling of the q-space, the practical truncation of the series of spherical harmonics and the use of a mono-exponential model for the attenuation of the measured signal. In this work, a detailed mathematical description that provides an extension to the DOT methodology is presented. In particular, the limitations implied by the use of measurements with a finite support in q-space are investigated and clarified as well as the impact of the harmonic series truncation. Near- and far-field analytical patterns for the diffusion propagator are examined. The near-field pattern makes available the direct computation of the probability of return to the origin. The far-field pattern allows probing the limitations of the mono-exponential model, which suggests the existence of a limit of validity for DOT. In the regimen from moderate to large displacement lengths the isosurfaces of the diffusion propagator reveal aberrations in form of artifactual peaks. Finally, the major contribution of this work is the derivation of analytical equations that facilitate the accurate reconstruction of some orientational distribution functions (ODFs) and skewness ODFs that are relatively immune to these artifacts. The new formalism was tested using synthetic and real data from a phantom of intersecting capillaries. The results support the hypothesis that the revisited DOT methodology could enhance the estimation of the microgeometry of fiber tissues.

Multiplex cytokine profiling with highly pathogenic material: use of formalin solution in luminex analysis.

PubMed

Dowall, Stuart D; Graham, Victoria A; Tipton, Thomas R W; Hewson, Roger

2009-08-31

Work with highly pathogenic material mandates the use of biological containment facilities, involving microbiological safety cabinets and specialist laboratory engineering structures typified by containment level 3 (CL3) and CL4 laboratories. Consequences of working in high containment are the practical difficulties associated with containing specialist assays and equipment often essential for experimental analyses. In an era of increased interest in biodefence pathogens and emerging diseases, immunological analysis has developed rapidly alongside traditional techniques in virology and molecular biology. For example, in order to maximise the use of small sample volumes, multiplexing has become a more popular and widespread approach to quantify multiple analytes simultaneously, such as cytokines and chemokines. The luminex microsphere system allows for the detection of many cytokines and chemokines in a single sample, but the detection method of using aligned lasers and fluidics means that samples often have to be analysed in low containment facilities. In order to perform cytokine analysis in materials from high containment (CL3 and CL4 laboratories), we have developed an appropriate inactivation methodology after staining steps, which although results in a reduction of median fluorescent intensity, produces statistically comparable outcomes when judged against non-inactivated samples. This methodology thus extends the use of luminex technology for material that contains highly pathogenic biological agents.

76 FR 55804 - Dicamba; Pesticide Tolerances

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-09

... Considerations A. Analytical Enforcement Methodology Adequate enforcement methodologies, Methods I and II--gas chromatography with electron capture detection (GC/ECD), are available to enforce the tolerance expression. The...

A Hybrid Coarse-graining Approach for Lipid Bilayers at Large Length and Time Scales

PubMed Central

Ayton, Gary S.; Voth, Gregory A.

2009-01-01

A hybrid analytic-systematic (HAS) coarse-grained (CG) lipid model is developed and employed in a large-scale simulation of a liposome. The methodology is termed hybrid analyticsystematic as one component of the interaction between CG sites is variationally determined from the multiscale coarse-graining (MS-CG) methodology, while the remaining component utilizes an analytic potential. The systematic component models the in-plane center of mass interaction of the lipids as determined from an atomistic-level MD simulation of a bilayer. The analytic component is based on the well known Gay-Berne ellipsoid of revolution liquid crystal model, and is designed to model the highly anisotropic interactions at a highly coarse-grained level. The HAS CG approach is the first step in an “aggressive” CG methodology designed to model multi-component biological membranes at very large length and timescales. PMID:19281167

FASP, an analytic resource appraisal program for petroleum play analysis

USGS Publications Warehouse

Crovelli, R.A.; Balay, R.H.

1986-01-01

An analytic probabilistic methodology for resource appraisal of undiscovered oil and gas resources in play analysis is presented in a FORTRAN program termed FASP. This play-analysis methodology is a geostochastic system for petroleum resource appraisal in explored as well as frontier areas. An established geologic model considers both the uncertainty of the presence of the assessed hydrocarbon and its amount if present. The program FASP produces resource estimates of crude oil, nonassociated gas, dissolved gas, and gas for a geologic play in terms of probability distributions. The analytic method is based upon conditional probability theory and many laws of expectation and variance. ?? 1986.

Reducing Conservatism of Analytic Transient Response Bounds via Shaping Filters

NASA Technical Reports Server (NTRS)

Kwan, Aiyueh; Bedrossian, Nazareth; Jan, Jiann-Woei; Grigoriadis, Karolos; Hua, Tuyen (Technical Monitor)

1999-01-01

Recent results show that the peak transient response of a linear system to bounded energy inputs can be computed using the energy-to-peak gain of the system. However, analytically computed peak response bound can be conservative for a class of class bounded energy signals, specifically pulse trains generated from jet firings encountered in space vehicles. In this paper, shaping filters are proposed as a Methodology to reduce the conservatism of peak response analytic bounds. This Methodology was applied to a realistic Space Station assembly operation subject to jet firings. The results indicate that shaping filters indeed reduce the predicted peak response bounds.

Determination of cocaine and its derivatives in hair samples by liquid phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS).

PubMed

Pego, A M F; Roveri, F L; Kuninari, R Y; Leyton, V; Miziara, I D; Yonamine, M

2017-05-01

Hair testing is a recognized approach when it comes to accessing historical drug use. According to the World Drug Report of United Nations Office on Drugs and Crime (UNODC) 2015, Brazil is the largest cocaine (COC) market in South America. New analytical methodologies to detect crack/cocaine analytes in hair samples are highly desirable. Here, a method consisting of a liquid-phase microextraction (LPME) as a clean-up step, followed by gas chromatography-mass spectrometry (GC-MS) analysis has been proposed. The new validated method consisted of a washing step; an overnight incubation with methanol and a quick derivatization with butylchloroformate. Once derivatized, the samples were then submitted to the LPME procedure. Limits of detection (LoD) and quantitation (LoQ) obtained were of 0.1 and 0.5ng/mg for COC 0.4 and 0.5ng/mg for anhydroecgonine methyl ester (AEME); 0.03 and 0.05 for cocaethylene (CE), respectively and 0.05ng/mg for both LoD and LoQ for benzoylecgonine (BZE). All calibration curves were linear over the scope applied, from LoQ up to 20ng/mg, with a r 2 >0.99. Precision and accuracy assays showed acceptable %RSD values, according to international guidelines. Twelve postmortem head hair samples stemming from the Institute of Legal Medicine of Sao Paulo (IML-SP) have been analyzed, from which seven have shown to be positive for COC (0.75->20ng/mg) and BZE (0.1->20ng/mg). Apart from COC's main metabolite, four samples were also positive for CE (0.1-3.9ng/mg) and three samples for AEME (0.5-4.9ng/mg). To conclude, the LPME technique together with GC-MS analysis have shown promising results and were able to meet the demand of the laboratory of analyzing postmortem hair samples to look for all four analytes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

MASS SPECTROMETRY FOR RISK MANAGEMENT OF DRINKING WATER TREATMENT; II. DISINFECTION BY-PRODUCTS: HALOACETIC ACIDS

EPA Science Inventory

Risk management of drinking water relies on quality analytical data. Analytical methodology can often be adapted from environmental monitoring sources. However, risk management sometimes presents special analytical challenges because data may be needed from a source for which n...

Microgenetic Learning Analytics Methods: Workshop Report

ERIC Educational Resources Information Center

Aghababyan, Ani; Martin, Taylor; Janisiewicz, Philip; Close, Kevin

2016-01-01

Learning analytics is an emerging discipline and, as such, benefits from new tools and methodological approaches. This work reviews and summarizes our workshop on microgenetic data analysis techniques using R, held at the second annual Learning Analytics Summer Institute in Cambridge, Massachusetts, on 30 June 2014. Specifically, this paper…

Ultrasound-assisted leaching-dispersive solid-phase extraction followed by liquid-liquid microextraction for the determination of polybrominated diphenyl ethers in sediment samples by gas chromatography-tandem mass spectrometry.

PubMed

Fontana, Ariel R; Lana, Nerina B; Martinez, Luis D; Altamirano, Jorgelina C

2010-06-30

Ultrasound-assisted leaching-dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction (USAL-DSPE-DLLME) technique has been developed as a new analytical approach for extracting, cleaning up and preconcentrating polybrominated diphenyl ethers (PBDEs) from sediment samples prior gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. In the first place, PBDEs were leached from sediment samples by using acetone. This extract was cleaned-up by DSPE using activated silica gel as sorbent material. After clean-up, PBDEs were preconcentrated by using DLLME technique. Thus, 1 mL acetone extract (disperser solvent) and 60 microL carbon tetrachloride (extraction solvent) were added to 5 mL ultrapure water and a DLLME technique was applied. Several variables that govern the proposed technique were studied and optimized. Under optimum conditions, the method detection limits (MDLs) of PBDEs calculated as three times the signal-to-noise ratio (S/N) were within the range 0.02-0.06 ng g(-1). The relative standard deviations (RSDs) for five replicates were <9.8%. The calibration graphs were linear within the concentration range of 0.07-1000 ng g(-1) for BDE-47, 0.09-1000 ng g(-1) for BDE-100, 0.10-1000 ng g(-1) for BDE-99 and 0.19-1000 ng g(-1) for BDE-153 and the coefficients of estimation were > or =0.9991. Validation of the methodology was carried out by standard addition method at two concentration levels (0.25 and 1 ng g(-1)) and by comparing with a reference Soxhlet technique. Recovery values were > or =80%, which showed a satisfactory robustness of the analytical methodology for determination of low PBDEs concentration in sediment samples. Copyright 2010 Elsevier B.V. All rights reserved.

Use of microextraction by packed sorbent directly coupled to an electron ionization single quadrupole mass spectrometer as an alternative for non-separative determinations.

PubMed

Casas Ferreira, Ana María; Moreno Cordero, Bernardo; Pérez Pavón, José Luis

2017-02-01

Sometimes it is not necessary to separate the individual compounds of a sample to resolve an analytical problem, it is enough to obtain a signal profile of the sample formed by all the components integrating it. Within this strategy, electronic noses based on the direct coupling of a headspace sampler with a mass spectrometer (HS-MS) have been proposed. Nevertheless, this coupling is not suitable for the analysis of non-volatile compounds. In order to propose an alternative to HS-MS determinations for non-volatile compounds, here we present the first 'proof of concept' use of the direct coupling of microextraction by packed sorbents (MEPS) to a mass spectrometer device using an electron ionization (EI) and a single quadrupole as ionization source and analyzer, respectively. As target compounds, a set of analytes with different physic-chemical properties were evaluated (2-ethyl-1-hexanol, styrene, 2-heptanone, among others). The use of MEPS extraction present many advantages, such as it is fast, simple, easy to automate and requires small volumes of sample and organic solvents. Moreover, MEPS cartridges are re-usable as samples can be extracted more than 100 times using the same syringe. In order to introduce into the system all the elution volume from the MEPS extraction, a programmable temperature vaporizer (PTV) is proposed as the injector device. Results obtained with the proposed methodology (MEPS-PTV/MS) were compared with the ones obtained based on the separative scheme, i.e. using gas chromatography separation (MEPS-PTV-GC/MS), and both methods provided similar results. Limits of detection were found to be between 3.26 and 146.6μgL -1 in the non-separative scheme and between 0.02 and 1.72μgL -1 when the separative methodology was used. Repeatability and reproducibility were evaluated with values below 17% in all cases. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of polyphosphates in fish and shrimps tissues by two different ion chromatography methods: implications on false-negative and -positive findings.

PubMed

Kaufmann, A; Maden, K; Leisser, W; Matera, M; Gude, T

2005-11-01

Inorganic polyphosphates (di-, tri- and higher polyphosphates) can be used to treat fish, fish fillets and shrimps in order to improve their water-binding capacity. The practical relevance of this treatment is a significant gain of weight caused by the retention/uptake of water and natural juice into the fish tissues. This practice is legal; however, the use of phosphates has to be declared. The routine control testing of fish for the presence of polyphosphates, produced some results that were difficult to explain. One of the two analytical methods used determined low diphosphate concentrations in a number of untreated samples, while the other ion chromatography (IC) method did not detect them. This initiated a number of investigations: results showed that polyphosphates in fish and shrimps tissue undergo a rapid enzymatic degradation, producing the ubiquitous orthophosphate. This led to the conclusion that sensitive analytical methods are required in order to detect previous polyphosphate treatment of a sample. The polyphosphate concentrations detected by one of the analytical methods could not be explained by the degradation of endogenous high-energy nucleotides like ATP into diphosphate, but by a coeluting compound. Further investigations by LC-MS-MS proved that the substance responsible for the observed peak was inosine monophsosphate (IMP) and not as thought the inorganic diphosphate. The method producing the false-positive result was modified and both methods were ultimately able to detect polyphosphates well separated from natural nucleotides. Polyphosphates could no longer be detected (<0.5 mg kg-1) after modification of the analytical methodology. The relevance of these findings lies in the fact that similar analytical methods are employed in various control laboratories, which might lead to false interpretation of measurements.

Automation practices in large molecule bioanalysis: recommendations from group L5 of the global bioanalytical consortium.

PubMed

Ahene, Ago; Calonder, Claudio; Davis, Scott; Kowalchick, Joseph; Nakamura, Takahiro; Nouri, Parya; Vostiar, Igor; Wang, Yang; Wang, Jin

2014-01-01

In recent years, the use of automated sample handling instrumentation has come to the forefront of bioanalytical analysis in order to ensure greater assay consistency and throughput. Since robotic systems are becoming part of everyday analytical procedures, the need for consistent guidance across the pharmaceutical industry has become increasingly important. Pre-existing regulations do not go into sufficient detail in regard to how to handle the use of robotic systems for use with analytical methods, especially large molecule bioanalysis. As a result, Global Bioanalytical Consortium (GBC) Group L5 has put forth specific recommendations for the validation, qualification, and use of robotic systems as part of large molecule bioanalytical analyses in the present white paper. The guidelines presented can be followed to ensure that there is a consistent, transparent methodology that will ensure that robotic systems can be effectively used and documented in a regulated bioanalytical laboratory setting. This will allow for consistent use of robotic sample handling instrumentation as part of large molecule bioanalysis across the globe.

Discovery and structural elucidation of the illegal azo dye Basic Red 46 in sumac spice.

PubMed

Ruf, J; Walter, P; Kandler, H; Kaufmann, A

2012-01-01

An unknown red dye was discovered in a sumac spice sample during routine analysis for Sudan dyes. LC-DAD and LC-MS/MS did not reveal the identity of the red substance. Nevertheless, using LC-high-resolution MS and isotope ratio comparisons the structure was identified as Basic Red 46. The identity of the dye was further confirmed by comparison with a commercial hair-staining product and two textile dye formulations containing Basic Red 46. Analogous to the Sudan dyes, Basic Red 46 is an azo dye. However, some of the sample clean-up methodology utilised for the analysis of Sudan dyes in food prevents its successful detection. In contrast to the Sudan dyes, Basic Red 46 is a cation. Its cationic properties make it bind strongly to gel permeation columns and silica solid-phase extraction cartridges and prevent elution with standard eluents. This is the first report of Basic Red 46 in food. The structure elucidation of this compound as well as the disadvantages of analytical methods focusing on a narrow group of targeted analytes are discussed.

Salting-out assisted liquid-liquid extraction coupled to ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of tetracycline residues in infant foods.

PubMed

Moreno-González, David; García-Campaña, Ana M

2017-04-15

The use of salting-out assisted liquid-liquid extraction (SALLE) combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) has been evaluated for the determination of tetracyclines in infant foods based on meat and vegetables or in milk. To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized. Analytical performances of the method were satisfactory, obtaining limits of quantification lower than 0.48μgkg -1 in all cases. The precision, expressed as relative standard deviation (%, RSD) was below 11.3%. The extraction efficiency for fortified samples ranged from 89.2 to 96.8%, with RSDs lower than 7.3%. Matrix effect was evaluated for all samples studied, being lower than |21|% in all cases. In relation to the low solvent consumption, the proposed methodology could be considered rapid, cheap and environmentally friendly. Its applicability has been successfully tested in a wide range of infant foods. Copyright © 2016 Elsevier Ltd. All rights reserved.

Portable laser-induced breakdown spectroscopy/diffuse reflectance hybrid spectrometer for analysis of inorganic pigments

NASA Astrophysics Data System (ADS)

Siozos, Panagiotis; Philippidis, Aggelos; Anglos, Demetrios

2017-11-01

A novel, portable spectrometer, combining two analytical techniques, laser-induced breakdown spectroscopy (LIBS) and diffuse reflectance spectroscopy, was developed with the aim to provide an enhanced instrumental and methodological approach with regard to the analysis of pigments in objects of cultural heritage. Technical details about the hybrid spectrometer and its operation are presented and examples are given relevant to the analysis of paint materials. Both LIBS and diffuse reflectance spectra in the visible and part of the near infrared, corresponding to several neat mineral pigment samples, were recorded and the complementary information was used to effectively distinguish different types of pigments even if they had similar colour or elemental composition. The spectrometer was also employed in the analysis of different paints on the surface of an ancient pottery sherd demonstrating the capabilities of the proposed hybrid diagnostic approach. Despite its instrumental simplicity and compact size, the spectrometer is capable of supporting analytical campaigns relevant to archaeological, historical or art historical investigations, particularly when quick data acquisition is required in the context of surveys of large numbers of objects and samples.

Evaluation of Aspergillus PCR protocols for testing serum specimens.

PubMed

White, P Lewis; Mengoli, Carlo; Bretagne, Stéphane; Cuenca-Estrella, Manuel; Finnstrom, Niklas; Klingspor, Lena; Melchers, Willem J G; McCulloch, Elaine; Barnes, Rosemary A; Donnelly, J Peter; Loeffler, Juergen

2011-11-01

A panel of human serum samples spiked with various amounts of Aspergillus fumigatus genomic DNA was distributed to 23 centers within the European Aspergillus PCR Initiative to determine analytical performance of PCR. Information regarding specific methodological components and PCR performance was requested. The information provided was made anonymous, and meta-regression analysis was performed to determine any procedural factors that significantly altered PCR performance. Ninety-seven percent of protocols were able to detect a threshold of 10 genomes/ml on at least one occasion, with 83% of protocols reproducibly detecting this concentration. Sensitivity and specificity were 86.1% and 93.6%, respectively. Positive associations between sensitivity and the use of larger sample volumes, an internal control PCR, and PCR targeting the internal transcribed spacer (ITS) region were shown. Negative associations between sensitivity and the use of larger elution volumes (≥100 μl) and PCR targeting the mitochondrial genes were demonstrated. Most Aspergillus PCR protocols used to test serum generate satisfactory analytical performance. Testing serum requires less standardization, and the specific recommendations shown in this article will only improve performance.

Evaluation of Aspergillus PCR Protocols for Testing Serum Specimens▿†

PubMed Central

White, P. Lewis; Mengoli, Carlo; Bretagne, Stéphane; Cuenca-Estrella, Manuel; Finnstrom, Niklas; Klingspor, Lena; Melchers, Willem J. G.; McCulloch, Elaine; Barnes, Rosemary A.; Donnelly, J. Peter; Loeffler, Juergen

2011-01-01

A panel of human serum samples spiked with various amounts of Aspergillus fumigatus genomic DNA was distributed to 23 centers within the European Aspergillus PCR Initiative to determine analytical performance of PCR. Information regarding specific methodological components and PCR performance was requested. The information provided was made anonymous, and meta-regression analysis was performed to determine any procedural factors that significantly altered PCR performance. Ninety-seven percent of protocols were able to detect a threshold of 10 genomes/ml on at least one occasion, with 83% of protocols reproducibly detecting this concentration. Sensitivity and specificity were 86.1% and 93.6%, respectively. Positive associations between sensitivity and the use of larger sample volumes, an internal control PCR, and PCR targeting the internal transcribed spacer (ITS) region were shown. Negative associations between sensitivity and the use of larger elution volumes (≥100 μl) and PCR targeting the mitochondrial genes were demonstrated. Most Aspergillus PCR protocols used to test serum generate satisfactory analytical performance. Testing serum requires less standardization, and the specific recommendations shown in this article will only improve performance. PMID:21940479

Analysis of Combined Data from Heterogeneous Study Designs: A Methodological Proposal from the Patient Navigation Research program

PubMed Central

Roetzheim, Richard G.; Freund, Karen M.; Corle, Don K.; Murray, David M.; Snyder, Frederick R.; Kronman, Andrea C.; Jean-Pierre, Pascal; Raich, Peter C.; Holden, Alan E. C.; Darnell, Julie S.; Warren-Mears, Victoria; Patierno, Steven; Design, PNRP; Committee, Analysis

2013-01-01

Background The Patient Navigation Research Program (PNRP) is a cooperative effort of nine research projects, each employing its own unique study design. To evaluate projects such as PNRP, it is desirable to perform a pooled analysis to increase power relative to the individual projects. There is no agreed upon prospective methodology, however, for analyzing combined data arising from different study designs. Expert opinions were thus solicited from members of the PNRP Design and Analysis Committee Purpose To review possible methodologies for analyzing combined data arising from heterogeneous study designs. Methods The Design and Analysis Committee critically reviewed the pros and cons of five potential methods for analyzing combined PNRP project data. Conclusions were based on simple consensus. The five approaches reviewed included: 1) Analyzing and reporting each project separately, 2) Combining data from all projects and performing an individual-level analysis, 3) Pooling data from projects having similar study designs, 4) Analyzing pooled data using a prospective meta analytic technique, 5) Analyzing pooled data utilizing a novel simulated group randomized design. Results Methodologies varied in their ability to incorporate data from all PNRP projects, to appropriately account for differing study designs, and in their impact from differing project sample sizes. Limitations The conclusions reached were based on expert opinion and not derived from actual analyses performed. Conclusions The ability to analyze pooled data arising from differing study designs may provide pertinent information to inform programmatic, budgetary, and policy perspectives. Multi-site community-based research may not lend itself well to the more stringent explanatory and pragmatic standards of a randomized controlled trial design. Given our growing interest in community-based population research, the challenges inherent in the analysis of heterogeneous study design are likely to become more salient. Discussion of the analytic issues faced by the PNRP and the methodological approaches we considered may be of value to other prospective community-based research programs. PMID:22273587

2016 Workplace and Gender Relations Survey of Active Duty Members: Statistical Methodology Report

DTIC Science & Technology

2017-03-01

2016 Workplace and Gender Relations Survey of Active Duty Members Statistical Methodology Report Additional copies of this report may be...MEMBERS: STATISTICAL METHODOLOGY REPORT Office of People Analytics (OPA) Defense Research, Surveys, and Statistics Center 4800 Mark Center Drive...20 1 2016 WORKPLACE AND GENDER RELATIONS SURVEY OF ACTIVE DUTY MEMBERS: STATISTICAL METHODOLOGY REPORT

Techniques used for the screening of hemoglobin levels in blood donors: current insights and future directions.

PubMed

Chaudhary, Rajendra; Dubey, Anju; Sonker, Atul

2017-01-01

Blood donor hemoglobin (Hb) estimation is an important donation test that is performed prior to blood donation. It serves the dual purpose of protecting the donors' health against anemia and ensuring good quality of blood components, which has an implication on recipients' health. Diverse cutoff criteria have been defined world over depending on population characteristics; however, no testing methodology and sample requirement have been specified for Hb screening. Besides the technique, there are several physiological and methodological factors that affect accuracy and reliability of Hb estimation. These include the anatomical source of blood sample, posture of the donor, timing of sample and several other biological factors. Qualitative copper sulfate gravimetric method has been the archaic time-tested method that is still used in resource-constrained settings. Portable hemoglobinometers are modern quantitative devices that have been further modified to reagent-free cuvettes. Furthermore, noninvasive spectrophotometry was introduced, mitigating pain to blood donor and eliminating risk of infection. Notwithstanding a tremendous evolution in terms of ease of operation, accuracy, mobility, rapidity and cost, a component of inherent variability persists, which may partly be attributed to pre-analytical variables. Hence, blood centers should pay due attention to validation of test methodology, competency of operating staff and regular proficiency testing of the outputs. In this article, we have reviewed various regulatory guidelines, described the variables that affect the measurements and compared the validated technologies for Hb screening of blood donors along with enumeration of their merits and limitations.

Comparative evaluation of liquid-liquid extraction, solid-phase extraction and solid-phase microextraction for the gas chromatography-mass spectrometry determination of multiclass priority organic contaminants in wastewater.

PubMed

Robles-Molina, José; Gilbert-López, Bienvenida; García-Reyes, Juan F; Molina-Díaz, Antonio

2013-12-15

The European Water Framework Directive (WFD) 2000/60/EC establishes guidelines to control the pollution of surface water by sorting out a list of priority substances that involves a significant risk to or via the aquatic systems. In this article, the analytical performance of three different sample preparation methodologies for the GC-MS/MS determination of multiclass organic contaminants-including priority comprounds from the WFD-in wastewater samples using gas chromatography-mass spectrometry was evaluated. The methodologies tested were: (a) liquid-liquid extraction (LLE) with n-hexane; (b) solid-phase extraction (SPE) with C18 cartridges and elution with ethyl acetate:dichloromethane (1:1 (v/v)), and (c) headspace solid-phase microextraction (HS-SPME) using two different fibers: polyacrylate and polydimethylsiloxane/carboxen/divinilbenzene. Identification and confirmation of the selected 57 compounds included in the study (comprising polycyclic aromatic hydrocarbons (PAHs), pesticides and other contaminants) were accomplished using gas chromatography tandem mass spectrometry (GC-MS/MS) with a triple quadrupole instrument operated in the multiple reaction monitoring (MRM) mode. Three MS/MS transitions were selected for unambiguous confirmation of the target chemicals. The different advantages and pitfalls of each method were discussed. In the case of both LLE and SPE procedures, the method was validated at two different concentration levels (15 and 150 ng L(-1)) obtaining recovery rates in the range 70-120% for most of the target compounds. In terms of analyte coverage, results with HS-SPME were not satisfactory, since 14 of the compounds tested were not properly recovered and the overall performance was worse than the other two methods tested. LLE, SPE and HS-SPME (using polyacrylate fiber) procedures also showed good linearity and precision. Using any of the three methodologies tested, limits of quantitation obtained for most of the detected compounds were in the low nanogram per liter range. © 2013 Elsevier B.V. All rights reserved.

Development of Carbotrap B-packed needle trap device for determination of volatile organic compounds in air.

PubMed

Poormohammadi, Ali; Bahrami, Abdulrahman; Farhadian, Maryam; Ghorbani Shahna, Farshid; Ghiasvand, Alireza

2017-12-08

Carbotrap B as a highly pure surface sorbent with excellent adsorption/desorption properties was packed into a stainless steel needle to develop a new needle trap device (NTD). The performance of the prepared NTD was investigated for sampling, pre-concentration and injection of benzene, toluene, ethyl benzene, o-xylene, and p-xylene (BTEX) into the column of gas chromatography-mass spectrometry (GC-MS) device. Response surface methodology (RSM) with central composite design (CCD) was also employed in two separate consecutive steps to optimize the sampling and device parameters. First, the sampling parameters such as sampling temperature and relative humidity were optimized. Afterwards, the RSM was used for optimizing the desorption parameters including desorption temperature and time. The results indicated that the peak area responses of the analytes of interest decreased with increasing sampling temperature and relative humidity. The optimum values of desorption temperature were in the range 265-273°C, and desorption time were in the range 3.4-3.8min. The limits of detection (LODs) and limits of quantitation (LOQs) of the studied analytes were found over the range of 0.03-0.04ng/mL, and 0.1-0.13ng/mL, respectively. These results demonstrated that the NTD packed with Carbotrap B offers a high sensitive procedure for sampling and analysis of BTEX in concentration range of 0.03-25ng/mL in air. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantitative evaluation of the CEEM soil sampling intercomparison.

PubMed

Wagner, G; Lischer, P; Theocharopoulos, S; Muntau, H; Desaules, A; Quevauviller, P

2001-01-08

The aim of the CEEM soil project was to compare and to test the soil sampling and sample preparation guidelines used in the member states of the European Union and Switzerland for investigations of background and large-scale contamination of soils, soil monitoring and environmental risk assessments. The results of the comparative evaluation of the sampling guidelines demonstrated that, in soil contamination studies carried out with different sampling strategies and methods, comparable results can hardly be expected. Therefore, a reference database (RDB) was established by the organisers, which acted as a basis for the quantitative comparison of the participants' results. The detected deviations were related to the methodological details of the individual strategies. The comparative evaluation concept consisted of three steps: The first step was a comparison of the participants' samples (which were both centrally and individually analysed) between each other, as well as with the reference data base (RDB) and some given soil quality standards on the level of concentrations present. The comparison was made using the example of the metals cadmium, copper, lead and zinc. As a second step, the absolute and relative deviations between the reference database and the participants' results (both centrally analysed under repeatability conditions) were calculated. The comparability of the samples with the RDB was categorised on four levels. Methods of exploratory statistical analysis were applied to estimate the differential method bias among the participants. The levels of error caused by sampling and sample preparation were compared with those caused by the analytical procedures. As a third step, the methodological profiles of the participants were compiled to concisely describe the different procedures used. They were related to the results to find out the main factors leading to their incomparability. The outcome of this evaluation process was a list of strategies and methods, which are problematic with respect to comparability, and should be standardised and/or specified in order to arrive at representative and comparable results in soil contamination studies throughout Europe. Pre-normative recommendations for harmonising European soil sampling guidelines and standard operating procedures have been outlined in Wagner G, Desules A, Muntau H, Theocharopoulos S. Comparative Evaluation of European Methods for Sampling and Sample Preparation of Soils for Inorganic Analysis (CEEM Soil). Final Report of the Contract SMT4-CT96-2085, Sci Total Environ 2001;264:181-186. Wagner G, Desaules A, Munatu H. Theocharopolous S, Quevauvaller Ph. Suggestions for harmonising sampling and sample pre-treatment procedures and improving quality assurance in pre-analytical steps of soil contamination studies. Paper 1.7 Sci Total Environ 2001b;264:103-118.

Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations

PubMed Central

PIÑEYRO-NELSON, A; VAN HEERWAARDEN, J; PERALES, H R; SERRATOS-HERNÁNDEZ, J A; RANGEL, A; HUFFORD, M B; GEPTS, P; GARAY-ARROYO, A; RIVERA-BUSTAMANTE, R; ÁLVAREZ-BUYLLA, E R

2009-01-01

A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces. PMID:19143938

Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations.

PubMed

Piñeyro-Nelson, A; Van Heerwaarden, J; Perales, H R; Serratos-Hernández, J A; Rangel, A; Hufford, M B; Gepts, P; Garay-Arroyo, A; Rivera-Bustamante, R; Alvarez-Buylla, E R

2009-02-01

A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces.

Hyperspectral imaging to investigate the distribution of organic matter and iron down the soil profile

NASA Astrophysics Data System (ADS)

Hobley, Eleanor; Kriegs, Stefanie; Steffens, Markus

2017-04-01

Obtaining reliable and accurate data regarding the spatial distribution of different soil components is difficult due to issues related with sampling scale and resolution on the one hand and laboratory analysis on the other. When investigating the chemical composition of soil, studies frequently limit themselves to two dimensional characterisations, e.g. spatial variability near the surface or depth distribution down the profile, but rarely combine both approaches due to limitations to sampling and analytical capacities. Furthermore, when assessing depth distributions, samples are taken according to horizon or depth increments, resulting in a mixed sample across the sampling depth. Whilst this facilitates mean content estimation per depth increment and therefore reduces analytical costs, the sample information content with regards to heterogeneity within the profile is lost. Hyperspectral imaging can overcome these sampling limitations, yielding high resolution spectral data of down the soil profile, greatly enhancing the information content of the samples. This can then be used to augment horizontal spatial characterisation of a site, yielding three dimensional information into the distribution of spectral characteristics across a site and down the profile. Soil spectral characteristics are associated with specific chemical components of soil, such as soil organic matter or iron contents. By correlating the content of these soil components with their spectral behaviour, high resolution multi-dimensional analysis of soil chemical composition can be obtained. Here we present a hyperspectral approach to the characterisation of soil organic matter and iron down different soil profiles, outlining advantages and issues associated with the methodology.

Direct Detection of Pharmaceuticals and Personal Care Products from Aqueous Samples with Thermally-Assisted Desorption Electrospray Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Campbell, Ian S.; Ton, Alain T.; Mulligan, Christopher C.

2011-07-01

An ambient mass spectrometric method based on desorption electrospray ionization (DESI) has been developed to allow rapid, direct analysis of contaminated water samples, and the technique was evaluated through analysis of a wide array of pharmaceutical and personal care product (PPCP) contaminants. Incorporating direct infusion of aqueous sample and thermal assistance into the source design has allowed low ppt detection limits for the target analytes in drinking water matrices. With this methodology, mass spectral information can be collected in less than 1 min, consuming ~100 μL of total sample. Quantitative ability was also demonstrated without the use of an internal standard, yielding decent linearity and reproducibility. Initial results suggest that this source configuration is resistant to carryover effects and robust towards multi-component samples. The rapid, continuous analysis afforded by this method offers advantages in terms of sample analysis time and throughput over traditional hyphenated mass spectrometric techniques.

Direct detection of pharmaceuticals and personal care products from aqueous samples with thermally-assisted desorption electrospray ionization mass spectrometry.

PubMed

Campbell, Ian S; Ton, Alain T; Mulligan, Christopher C

2011-07-01

An ambient mass spectrometric method based on desorption electrospray ionization (DESI) has been developed to allow rapid, direct analysis of contaminated water samples, and the technique was evaluated through analysis of a wide array of pharmaceutical and personal care product (PPCP) contaminants. Incorporating direct infusion of aqueous sample and thermal assistance into the source design has allowed low ppt detection limits for the target analytes in drinking water matrices. With this methodology, mass spectral information can be collected in less than 1 min, consuming ~100 μL of total sample. Quantitative ability was also demonstrated without the use of an internal standard, yielding decent linearity and reproducibility. Initial results suggest that this source configuration is resistant to carryover effects and robust towards multi-component samples. The rapid, continuous analysis afforded by this method offers advantages in terms of sample analysis time and throughput over traditional hyphenated mass spectrometric techniques.

Versatile fluid-mixing device for cell and tissue microgravity research applications.

PubMed

Wilfinger, W W; Baker, C S; Kunze, E L; Phillips, A T; Hammerstedt, R H

1996-01-01

Microgravity life-science research requires hardware that can be easily adapted to a variety of experimental designs and working environments. The Biomodule is a patented, computer-controlled fluid-mixing device that can accommodate these diverse requirements. A typical shuttle payload contains eight Biomodules with a total of 64 samples, a sealed containment vessel, and a NASA refrigeration-incubation module. Each Biomodule contains eight gas-permeable Silastic T tubes that are partitioned into three fluid-filled compartments. The fluids can be mixed at any user-specified time. Multiple investigators and complex experimental designs can be easily accommodated with the hardware. During flight, the Biomodules are sealed in a vessel that provides two levels of containment (liquids and gas) and a stable, investigator-controlled experimental environment that includes regulated temperature, internal pressure, humidity, and gas composition. A cell microencapsulation methodology has also been developed to streamline launch-site sample manipulation and accelerate postflight analysis through the use of fluorescent-activated cell sorting. The Biomodule flight hardware and analytical cell encapsulation methodology are ideally suited for temporal, qualitative, or quantitative life-science investigations.

Speciation analysis of organotin compounds in human urine by headspace solid-phase micro-extraction and gas chromatography with pulsed flame photometric detection.

PubMed

Valenzuela, Aníbal; Lespes, Gaëtane; Quiroz, Waldo; Aguilar, Luis F; Bravo, Manuel A

2014-07-01

A new headspace solid-phase micro-extraction (HS-SPME) method followed by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis has been developed for the simultaneous determination of 11 organotin compounds, including methyl-, butyl-, phenyl- and octyltin derivates, in human urine. The methodology has been validated by the analysis of urine samples fortified with all analytes at different concentration levels, and recovery rates above 87% and relative precisions between 2% and 7% were obtained. Additionally, an experimental-design approach has been used to model the storage stability of organotin compounds in human urine, demonstrating that organotins are highly degraded in this medium, although their stability is satisfactory during the first 4 days of storage at 4 °C and pH=4. Finally, this methodology was applied to urine samples collected from harbor workers exposed to antifouling paints; methyl- and butyltins were detected, confirming human exposure in this type of work environment. Copyright © 2014 Elsevier B.V. All rights reserved.

Elemental labelling combined with liquid chromatography inductively coupled plasma mass spectrometry for quantification of biomolecules: A review

PubMed Central

Kretschy, Daniela; Koellensperger, Gunda; Hann, Stephan

2012-01-01

This article reviews novel quantification concepts where elemental labelling is combined with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS) or liquid chromatography inductively coupled plasma mass spectrometry (LC–ICP-MS), and employed for quantification of biomolecules such as proteins, peptides and related molecules in challenging sample matrices. In the first sections an overview on general aspects of biomolecule quantification, as well as of labelling will be presented emphasizing the potential, which lies in such methodological approaches. In this context, ICP-MS as detector provides high sensitivity, selectivity and robustness in biological samples and offers the capability for multiplexing and isotope dilution mass spectrometry (IDMS). Fundamental methodology of elemental labelling will be highlighted and analytical, as well as biomedical applications will be presented. A special focus will lie on established applications underlining benefits and bottlenecks of such approaches for the implementation in real life analysis. Key research made in this field will be summarized and a perspective for future developments including sophisticated and innovative applications will given. PMID:23062431

Opening up openness: a theoretical sort following critical incidents methodology and a meta-analytic investigation of the trait family measures.

PubMed

Connelly, Brian S; Ones, Deniz S; Davies, Stacy E; Birkland, Adib

2014-01-01

Existing taxonomies of Openness's facet structure have produced widely divergent results, and there is limited comprehensive empirical evidence about how Openness-related scales on existing personality inventories align within the 5-factor framework. In Study 1, we used a critical incidents sorting methodology to identify 11 categories of Openness measures; in Study 2, we meta-analyzed the relationships of these categories with global markers of the Big Five traits (utilizing data from 106 samples with a total sample size of N = 35,886). Our results identified 4 true facets of Openness: aestheticism, openness to sensations, nontraditionalism, and introspection. Measures of these facets were unadulterated by variance from other Big Five traits. Many traits frequently conceptualized as facets of Openness (e.g., innovation/creativity, variety-seeking, and tolerance) emerged as trait compounds that, although related to Openness, are also dependent on other Big Five traits. We discuss how Openness should be conceptualized, measured, and studied in light of the empirically based, refined taxonomy emerging from this research.

A framework for inference about carnivore density from unstructured spatial sampling of scat using detector dogs

USGS Publications Warehouse

Thompson, Craig M.; Royle, J. Andrew; Garner, James D.

2012-01-01

Wildlife management often hinges upon an accurate assessment of population density. Although undeniably useful, many of the traditional approaches to density estimation such as visual counts, livetrapping, or mark–recapture suffer from a suite of methodological and analytical weaknesses. Rare, secretive, or highly mobile species exacerbate these problems through the reality of small sample sizes and movement on and off study sites. In response to these difficulties, there is growing interest in the use of non-invasive survey techniques, which provide the opportunity to collect larger samples with minimal increases in effort, as well as the application of analytical frameworks that are not reliant on large sample size arguments. One promising survey technique, the use of scat detecting dogs, offers a greatly enhanced probability of detection while at the same time generating new difficulties with respect to non-standard survey routes, variable search intensity, and the lack of a fixed survey point for characterizing non-detection. In order to account for these issues, we modified an existing spatially explicit, capture–recapture model for camera trap data to account for variable search intensity and the lack of fixed, georeferenced trap locations. We applied this modified model to a fisher (Martes pennanti) dataset from the Sierra National Forest, California, and compared the results (12.3 fishers/100 km2) to more traditional density estimates. We then evaluated model performance using simulations at 3 levels of population density. Simulation results indicated that estimates based on the posterior mode were relatively unbiased. We believe that this approach provides a flexible analytical framework for reconciling the inconsistencies between detector dog survey data and density estimation procedures.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products.

PubMed

Collier, J W; Shah, R B; Bryant, A R; Habib, M J; Khan, M A; Faustino, P J

2011-02-20

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. Published by Elsevier B.V.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

PubMed Central

Collier, J.W.; Shah, R.B.; Bryant, A.R.; Habib, M.J.; Khan, M.A.; Faustino, P.J.

2011-01-01

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (l-T4) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250mm × 3.9mm) using a 0.01 M phosphate buffer (pH 3.0)–methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 µL and the column temperature was maintained at 28 °C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r2 > 0.99) over the analytical range of 0.08–0.8 µg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for l-T4 over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. PMID:20947276

Unbiased Scanning Method and Data Banking Approach Using Ultra-High Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry for Quantitative Comparison of Metabolite Exposure in Plasma across Species Analyzed at Different Dates.

PubMed

Gao, Hongying; Deng, Shibing; Obach, R Scott

2015-12-01

An unbiased scanning methodology using ultra high-performance liquid chromatography coupled with high-resolution mass spectrometry was used to bank data and plasma samples for comparing the data generated at different dates. This method was applied to bank the data generated earlier in animal samples and then to compare the exposure to metabolites in animal versus human for safety assessment. With neither authentic standards nor prior knowledge of the identities and structures of metabolites, full scans for precursor ions and all ion fragments (AIF) were employed with a generic gradient LC method to analyze plasma samples at positive and negative polarity, respectively. In a total of 22 tested drugs and metabolites, 21 analytes were detected using this unbiased scanning method except that naproxen was not detected due to low sensitivity at negative polarity and interference at positive polarity; and 4'- or 5-hydroxy diclofenac was not separated by a generic UPLC method. Statistical analysis of the peak area ratios of the analytes versus the internal standard in five repetitive analyses over approximately 1 year demonstrated that the analysis variation was significantly different from sample instability. The confidence limits for comparing the exposure using peak area ratio of metabolites in animal plasma versus human plasma measured over approximately 1 year apart were comparable to the analysis undertaken side by side on the same days. These statistical analysis results showed it was feasible to compare data generated at different dates with neither authentic standards nor prior knowledge of the analytes.

Development of a highly sensitive methodology for quantitative determination of fexofenadine in a microdose study by multiple injection method using ultra-high performance liquid chromatography with tandem mass spectrometry.

PubMed

Tanaka, Yukari; Yoshikawa, Yutaka; Yasui, Hiroyuki

2012-01-01

An ultra high-sensitivity method for quantifying fexofenadine concentration in rat plasma samples by multiple injection method (MIM) was developed for a microdose study. In this study, MIM involved continuous injections of multiple samples containing the single compound into a column of the ultra-HPLC (UHPLC) system, and then, temporary trapping of the analyte at the column head. This was followed by elution of the compound from the column and detection by mass spectrometer. Fexofenadine, used as a model compound in this study, was extracted from the plasma samples by a protein precipitation method. Chromatographic separation was achieved on a reversed-phase C18 column by using a gradient method with 0.1% formic acid and 0.1% formic acid in acetonitrile as the mobile phase. The analyte was quantified in the positive-ion electrospray ionization mode using selected reaction monitoring. In this study, the analytical time per fexofenadine sample was approximately 2 min according to the UHPLC system. The method exhibited the linear dynamic ranges of 5-5000 pg/mL for fexofenadine in rat plasma. The intra-day precisions were from 3.2 to 8.7% and the accuracy range was 95.2-99.3%. The inter-day precisions and accuracies ranged from 3.5 to 8.4% and from 98.6 to 102.6%, respectively. The validated MIM was successfully applied to a microdose study in the rats that received oral administration of 100 µg/kg fexofenadine. We suggest that this method might be beneficial for the quantification of fexofenadine concentrations in a microdose clinical study.

Chemical-mineralogical characterization of C and D waste recycled aggregates from Sao Paulo, Brazil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angulo, S.C.; Ulsen, C.; John, V.M.

2009-02-15

This study presents a methodology for the characterization of construction and demolition (C and D) waste recycled aggregates based on a combination of analytical techniques (X-ray fluorescence (XRF), soluble ions, semi-quantitative X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTG) and hydrochloric acid (HCl) selective dissolution). These combined analytical techniques allow for the estimation of the amount of cement paste, its most important hydrated and carbonated phases, as well as the amount of clay and micas. Details of the methodology are presented here and the results of three representative C and D samples taken from the Sao Paulo region in Brazil are discussed.more » Chemical compositions of mixed C and D aggregate samples have mostly been influenced by particle size rather than the visual classification of C and D into red or grey and geographical origin. The amount of measured soluble salts in C and D aggregates (0.15-25.4 mm) is lower than the usual limits for mortar and concrete production. The content of porous cement paste in the C and D aggregates is around 19.3% (w/w). However, this content is significantly lower than the 43% detected for the C and D powders (<0.15 mm). The clay content of the powders was also high, potentially resulting from soil intermixed with the C and D waste, as well as poorly burnt red ceramic. Since only about 50% of the measured CaO is combined with CO{sub 2}, the powders have potential use as raw materials for the cement industry.« less

Optimization of the treatment of wheat samples for the determination of phytic acid by HPLC with refractive index detection.

PubMed

Amaro, Rosa; Murillo, Miguel; González, Zurima; Escalona, Andrés; Hernández, Luís

2009-01-01

The treatment of wheat samples was optimized before the determination of phytic acid by high-performance liquid chromatography with refractive index detection. Drying by lyophilization and oven drying were studied; drying by lyophilization gave better results, confirming that this step is critical in preventing significant loss of analyte. In the extraction step, washing of the residue and collection of this water before retention of the phytates in the NH2 Sep-Pak cartridge were important. The retention of phytates in the NH2 Sep-Pak cartridge and elimination of the HCI did not produce significant loss (P = 0.05) in the phytic acid content of the sample. Recoveries of phytic acid averaged 91%, which is a substantial improvement with respect to values reported by others using this methodology.

Recent Application of Solid Phase Based Techniques for Extraction and Preconcentration of Cyanotoxins in Environmental Matrices.

PubMed

Mashile, Geaneth Pertunia; Nomngongo, Philiswa N

2017-03-04

Cyanotoxins are toxic and are found in eutrophic, municipal, and residential water supplies. For this reason, their occurrence in drinking water systems has become a global concern. Therefore, monitoring, control, risk assessment, and prevention of these contaminants in the environmental bodies are important subjects associated with public health. Thus, rapid, sensitive, selective, simple, and accurate analytical methods for the identification and determination of cyanotoxins are required. In this paper, the sampling methodologies and applications of solid phase-based sample preparation methods for the determination of cyanotoxins in environmental matrices are reviewed. The sample preparation techniques mainly include solid phase micro-extraction (SPME), solid phase extraction (SPE), and solid phase adsorption toxin tracking technology (SPATT). In addition, advantages and disadvantages and future prospects of these methods have been discussed.

Health Insurance Dynamics: Methodological Considerations and a Comparison of Estimates from Two Surveys.

PubMed

Graves, John A; Mishra, Pranita

2016-10-01

To highlight key methodological issues in studying insurance dynamics and to compare estimates across two commonly used surveys. Nonelderly uninsured adults and children sampled between 2001 and 2011 in the Medical Expenditure Panel Survey and the Survey of Income and Program Participation. We utilized nonparametric Kaplan-Meier methods to estimate quantiles (25th, 50th, and 75th percentiles) in the distribution of uninsured spells. We compared estimates obtained across surveys and across different methodological approaches to address issues like attrition, seam bias, censoring and truncation, and survey weighting method. All data were drawn from publicly available household surveys. Estimated uninsured spell durations in the MEPS were longer than those observed in the SIPP. There were few changes in spell durations between 2001 and 2011, with median durations of 14 months among adults and 5-7 months among children in the MEPS, and 8 months (adults) and 4 months (children) in the SIPP. The use of panel survey data to study insurance dynamics presents a unique set of methodological challenges. Researchers should consider key analytic and survey design trade-offs when choosing which survey can best suit their research goals. © Health Research and Educational Trust.

Nationwide Multicenter Reference Interval Study for 28 Common Biochemical Analytes in China.

PubMed

Xia, Liangyu; Chen, Ming; Liu, Min; Tao, Zhihua; Li, Shijun; Wang, Liang; Cheng, Xinqi; Qin, Xuzhen; Han, Jianhua; Li, Pengchang; Hou, Li'an; Yu, Songlin; Ichihara, Kiyoshi; Qiu, Ling

2016-03-01

A nationwide multicenter study was conducted in the China to explore sources of variation of reference values and establish reference intervals for 28 common biochemical analytes, as a part of the International Federation of Clinical Chemistry and Laboratory Medicine, Committee on Reference Intervals and Decision Limits (IFCC/C-RIDL) global study on reference values. A total of 3148 apparently healthy volunteers were recruited in 6 cities covering a wide area in China. Blood samples were tested in 2 central laboratories using Beckman Coulter AU5800 chemistry analyzers. Certified reference materials and value-assigned serum panel were used for standardization of test results. Multiple regression analysis was performed to explore sources of variation. Need for partition of reference intervals was evaluated based on 3-level nested ANOVA. After secondary exclusion using the latent abnormal values exclusion method, reference intervals were derived by a parametric method using the modified Box-Cox formula. Test results of 20 analytes were made traceable to reference measurement procedures. By the ANOVA, significant sex-related and age-related differences were observed in 12 and 12 analytes, respectively. A small regional difference was observed in the results for albumin, glucose, and sodium. Multiple regression analysis revealed BMI-related changes in results of 9 analytes for man and 6 for woman. Reference intervals of 28 analytes were computed with 17 analytes partitioned by sex and/or age. In conclusion, reference intervals of 28 common chemistry analytes applicable to Chinese Han population were established by use of the latest methodology. Reference intervals of 20 analytes traceable to reference measurement procedures can be used as common reference intervals, whereas others can be used as the assay system-specific reference intervals in China.

Nationwide Multicenter Reference Interval Study for 28 Common Biochemical Analytes in China

PubMed Central

Xia, Liangyu; Chen, Ming; Liu, Min; Tao, Zhihua; Li, Shijun; Wang, Liang; Cheng, Xinqi; Qin, Xuzhen; Han, Jianhua; Li, Pengchang; Hou, Li’an; Yu, Songlin; Ichihara, Kiyoshi; Qiu, Ling

2016-01-01

Abstract A nationwide multicenter study was conducted in the China to explore sources of variation of reference values and establish reference intervals for 28 common biochemical analytes, as a part of the International Federation of Clinical Chemistry and Laboratory Medicine, Committee on Reference Intervals and Decision Limits (IFCC/C-RIDL) global study on reference values. A total of 3148 apparently healthy volunteers were recruited in 6 cities covering a wide area in China. Blood samples were tested in 2 central laboratories using Beckman Coulter AU5800 chemistry analyzers. Certified reference materials and value-assigned serum panel were used for standardization of test results. Multiple regression analysis was performed to explore sources of variation. Need for partition of reference intervals was evaluated based on 3-level nested ANOVA. After secondary exclusion using the latent abnormal values exclusion method, reference intervals were derived by a parametric method using the modified Box–Cox formula. Test results of 20 analytes were made traceable to reference measurement procedures. By the ANOVA, significant sex-related and age-related differences were observed in 12 and 12 analytes, respectively. A small regional difference was observed in the results for albumin, glucose, and sodium. Multiple regression analysis revealed BMI-related changes in results of 9 analytes for man and 6 for woman. Reference intervals of 28 analytes were computed with 17 analytes partitioned by sex and/or age. In conclusion, reference intervals of 28 common chemistry analytes applicable to Chinese Han population were established by use of the latest methodology. Reference intervals of 20 analytes traceable to reference measurement procedures can be used as common reference intervals, whereas others can be used as the assay system-specific reference intervals in China. PMID:26945390

Quality-control results for ground-water and surface-water data, Sacramento River Basin, California, National Water-Quality Assessment, 1996-1998

USGS Publications Warehouse

Munday, Cathy; Domagalski, Joseph L.

2003-01-01

Evaluating the extent that bias and variability affect the interpretation of ground- and surface-water data is necessary to meet the objectives of the National Water-Quality Assessment (NAWQA) Program. Quality-control samples used to evaluate the bias and variability include annual equipment blanks, field blanks, field matrix spikes, surrogates, and replicates. This report contains quality-control results for the constituents critical to the ground- and surface-water components of the Sacramento River Basin study unit of the NAWQA Program. A critical constituent is one that was detected frequently (more than 50 percent of the time in blank samples), was detected at amounts exceeding water-quality standards or goals, or was important for the interpretation of water-quality data. Quality-control samples were collected along with ground- and surface-water samples during the high intensity phase (cycle 1) of the Sacramento River Basin NAWQA beginning early in 1996 and ending in 1998. Ground-water field blanks indicated contamination of varying levels of significance when compared with concentrations detected in environmental ground-water samples for ammonia, dissolved organic carbon, aluminum, and copper. Concentrations of aluminum in surface-water field blanks were significant when compared with environmental samples. Field blank samples collected for pesticide and volatile organic compound analyses revealed no contamination in either ground- or surface-water samples that would effect the interpretation of environmental data, with the possible exception of the volatile organic compound trichloromethane (chloroform) in ground water. Replicate samples for ground water and surface water indicate that variability resulting from sample collection, processing, and analysis was generally low. Some of the larger maximum relative percentage differences calculated for replicate samples occurred between samples having lowest absolute concentration differences and(or) values near the reporting limit. Surrogate recoveries for pesticides analyzed by gas chromatography/mass spectrometry (GC/MS), pesticides analyzed by high performance liquid chromatography (HPLC), and volatile organic compounds in ground- and surface-water samples were within the acceptable limits of 70 to 130 percent and median recovery values between 82 and 113 percent. The recovery percentages for surrogate compounds analyzed by HPLC had the highest standard deviation, 20 percent for ground-water samples and 16 percent for surface-water samples, and the lowest median values, 82 percent for ground-water samples and 91 percent for surface-water samples. Results were consistent with the recovery results described for the analytical methods. Field matrix spike recoveries for pesticide compounds analyzed using GC/MS in ground- and surface-water samples were comparable with published recovery data. Recoveries of carbofuran, a critical constituent in ground- and surface-water studies, and desethyl atrazine, a critical constituent in the ground-water study, could not be calculated because of problems with the analytical method. Recoveries of pesticides analyzed using HPLC in ground- and surface-water samples were generally low and comparable with published recovery data. Other methodological problems for HPLC analytes included nondetection of the spike compounds and estimated values of spike concentrations. Recovery of field matrix spikes for volatile organic compounds generally were within the acceptable range, 70 and 130 percent for both ground- and surface-water samples, and median recoveries from 62 to 127 percent. High or low recoveries could be related to errors in the field, such as double spiking or using spike solution past its expiration date, rather than problems during analysis. The methodological changes in the field spike protocol during the course of the Sacramento River Basin study, which included decreasing the amount of spike solu

Determination of Ochratoxin A in wine by packed in-tube solid phase microextraction followed by high performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Andrade, Mariane A; Lanças, Fernando M

2017-04-14

Ochratoxin A (OTA), a widely studied mycotoxin, can be found in a variety of food matrices. As its concentration in food is generally low (in the order of μg kg -1 ), sample preparation techniques are necessary for the analyte purification and pre-concentration in order to achieve the required low detection limits. The separation and detection methods used for OTA analysis should also offer proper sensitivity in order to allow the adequate quantification of the analyte. This manuscript addresses the development of a methodology aiming the analysis of OTA in wine samples by packed in-tube SPME in flow through extraction mode coupled to HPLC-MS/MS. The in-tube SPME set up utilized a PEEK tube packed with C18 particles as the extraction column. The method was optimized by a central composite design 2 2 +3 extra central points, having as factors the percentage of ACN and time in the sample load step. The functionalities of the method were attested and its analytical conditions, enhanced by using 22% of ACN and 6min in the sample load step. Validation of the method was also accomplished prior to analyses of both dry red wine and dry white wine samples. The method demonstrated proper sensitivity, with detection and quantification limits equal to 0.02 and 0.05μgL -1 , respectively. Linearity and precision exhibited a 0.996 correlation coefficient and RSD under 6%, respectively. The method proved to be accurate at medium and higher concentration levels with a maximum recovery of 73% at higher concentration levels. OTA was not detected in either dry red and dry white wine samples evaluated in this work. If present, it would be at concentrations lower than the detection and quantification limits established for the proposed method, and considered not a potential danger to human health according to our present knowledge. Copyright © 2017 Elsevier B.V. All rights reserved.

Large-scale pesticide testing in olives by liquid chromatography-electrospray tandem mass spectrometry using two sample preparation methods based on matrix solid-phase dispersion and QuEChERS.

PubMed

Gilbert-López, Bienvenida; García-Reyes, Juan F; Lozano, Ana; Fernández-Alba, Amadeo R; Molina-Díaz, Antonio

2010-09-24

In this work we have evaluated the performance of two sample preparation methodologies for the large-scale multiresidue analysis of pesticides in olives using liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). The tested sample treatment methodologies were: (1) liquid-liquid partitioning with acetonitrile followed by dispersive solid-phase extraction clean-up using GCB, PSA and C18 sorbents (QuEChERS method - modified for fatty vegetables) and (2) matrix solid-phase dispersion (MSPD) using aminopropyl as sorbent material and a final clean-up performed in the elution step using Florisil. An LC-MS/MS method covering 104 multiclass pesticides was developed to examine the performance of these two protocols. The separation of the compounds from the olive extracts was achieved using a short C18 column (50 mm x 4.6 mm i.d.) with 1.8 microm particle size. The identification and confirmation of the compounds was based on retention time matching along with the presence (and ratio) of two typical MRM transitions. Limits of detection obtained were lower than 10 microgkg(-1) for 89% analytes using both sample treatment protocols. Recoveries studies performed on olives samples spiked at two concentration levels (10 and 100 microgkg(-1)) yielded average recoveries in the range 70-120% for most analytes when QuEChERS procedure is employed. When MSPD was the choice for sample extraction, recoveries obtained were in the range 50-70% for most of target compounds. The proposed methods were successfully applied to the analysis of real olives samples, revealing the presence of some of the target species in the microgkg(-1) range. Besides the evaluation of the sample preparation approaches, we also discuss the use of advanced software features associated to MRM method development that overcome several limitations and drawbacks associated to MS/MS methods (time segments boundaries, tedious method development/manual scheduling and acquisition limitations). This software feature recently offered by different vendors is based on an algorithm that associates retention time data for each individual MS/MS transition, so that the number of simultaneously traced transitions throughout the entire chromatographic run (dwell times and sensitivity) is maximized. Copyright 2010 Elsevier B.V. All rights reserved.

Immunological screening of drugs of abuse and gas chromatographic-mass spectrometric confirmation of opiates and cocaine in hair.

PubMed

Segura, J; Stramesi, C; Redón, A; Ventura, M; Sanchez, C J; González, G; San, L; Montagna, M

1999-03-05

The work presents an analytical strategy to detect drugs of abuse in hair. It involves two sequential steps: a screening by a simple enzyme-linked immunosorbent assay (ELISA) methodology to detect opiates, cocaine and its metabolites, and benzodiacepines, followed by confirmation of opiates and cocaine metabolites in positive samples by gas chromatography coupled to mass spectrometry (GC-MS). In the same GC-MS run other drugs for substitution therapy (e.g. methadone and its main metabolite) can also be detected. After a double washing of hair samples with dichloromethane, hair specimens were cut into small pieces and 10 mg samples were incubated in 2 ml of methanol-trifluoroacetic acid (9:1) mixture, overnight at 37 degrees C. Aliquots of the extract were then evaporated, reconstituted in buffer and analysed according to the ELISA procedure. Confirmation involved solid-phase extraction of another fraction of the extract kept at -20 degrees C, derivatization with heptafluorobutyric anhydride and hexafluoroisopropanol and detection of cocaine, benzoylecgonine, ecgonine methylester, cocaethylene, morphine, codeine, 6-monoacetylmorphine, methadone and 2-ethylidene-1.5-dimethyl-3,3-diphenylpirrolidine (methadone metabolite) by selective ion monitoring after gas chromatographic separation. During the development of the method it was verified that no more than 10% of cocaine, opiates and benzodiacepines were lost when dichloromethane was used to wash real samples. The results also confirmed the increase of extractability power of TFA when it was added to methanol: the recovery for the analytes (cocaine and its metabolites and opiates) added to methanol-TFA alone was of the order of 90% except for benzoylecgonine (75%), and the recovery for the analytes added to methanol-TFA extract of drug-free hair was about 90% for all analytes except for benzoylecgonine and 6-MAM (around 70%). Regarding the stability of labile compounds, only small amounts of ecgonine methylester (2.3%) and morphine (7.2%) were produced, from cocaine and 6-MAM respectively, after the whole extraction procedure and two weeks of storage of methanol-TFA extracts at -20 degrees C. Satisfactory results were obtained when the procedures were applied to the analysis of external proficiency testing hair samples and actual specimens from drug addicts.

Simultaneous LC-MS/MS determination of 40 legal and illegal psychoactive drugs in breast and bovine milk.

PubMed

López-García, Ester; Mastroianni, Nicola; Postigo, Cristina; Valcárcel, Yolanda; González-Alonso, Silvia; Barceló, Damia; López de Alda, Miren

2018-04-15

This work presents a fast, sensitive and reliable multi-residue methodology based on fat and protein precipitation and liquid chromatography-tandem mass spectrometry for the determination of common legal and illegal psychoactive drugs, and major metabolites, in breast milk. One-fourth of the 40 target analytes is investigated for the first time in this biological matrix. The method was validated in breast milk and also in various types of bovine milk, as tranquilizers are occasionally administered to food-producing animals. Absolute recoveries were satisfactory for 75% of the target analytes. The use of isotopically labeled compounds assisted in correcting analyte losses due to ionization suppression matrix effects (higher in whole milk than in the other investigated milk matrices) and ensured the reliability of the results. Average method limits of quantification ranged between 0.4 and 6.8 ng/mL. Application of the developed method showed the presence of caffeine in breast milk samples (12-179 ng/mL). Copyright © 2017 Elsevier Ltd. All rights reserved.

Generalized Subset Designs in Analytical Chemistry.

PubMed

Surowiec, Izabella; Vikström, Ludvig; Hector, Gustaf; Johansson, Erik; Vikström, Conny; Trygg, Johan

2017-06-20

Design of experiments (DOE) is an established methodology in research, development, manufacturing, and production for screening, optimization, and robustness testing. Two-level fractional factorial designs remain the preferred approach due to high information content while keeping the number of experiments low. These types of designs, however, have never been extended to a generalized multilevel reduced design type that would be capable to include both qualitative and quantitative factors. In this Article we describe a novel generalized fractional factorial design. In addition, it also provides complementary and balanced subdesigns analogous to a fold-over in two-level reduced factorial designs. We demonstrate how this design type can be applied with good results in three different applications in analytical chemistry including (a) multivariate calibration using microwave resonance spectroscopy for the determination of water in tablets, (b) stability study in drug product development, and (c) representative sample selection in clinical studies. This demonstrates the potential of generalized fractional factorial designs to be applied in many other areas of analytical chemistry where representative, balanced, and complementary subsets are required, especially when a combination of quantitative and qualitative factors at multiple levels exists.

Enantiomeric separation of non-protein amino acids by electrokinetic chromatography.

PubMed

Pérez-Míguez, Raquel; Marina, María Luisa; Castro-Puyana, María

2016-10-07

New analytical methodologies enabling the enantiomeric separation of a group of non-protein amino acids of interest in the pharmaceutical and food analysis fields were developed in this work using Electrokinetic Chromatography. The use of FMOC as derivatization reagent and the subsequent separation using acidic conditions (formate buffer at pH 2.0) and anionic cyclodextrins as chiral selectors allowed the chiral separation of eight from the ten non-protein amino acids studied. Pyroglutamic acid, norvaline, norleucine, 3,4-dihydroxyphenilalanine, 2-aminoadipic acid, and selenomethionine were enantiomericaly separated using sulfated-α-CD while sulfated-γ-CD enabled the enantiomeric separation of norvaline, 3,4-dihydroxyphenilalanine, 2-aminoadipic acid, selenomethionie, citrulline, and pipecolic acid. Moreover, the potential of the developed methodologies was demonstrated in the analysis of citrulline and its enantiomeric impurity in food supplements. For that purpose, experimental and instrumental variables were optimized and the analytical characteristics of the proposed method were evaluated. LODs of 2.1×10 -7 and 1.8×10 -7 M for d- and l-citrulline, respectively, were obtained. d-Cit was not detectable in any of the six food supplement samples analyzed showing that the effect of storage time on the racemization of citrulline was negligible. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative mass spectrometry of unconventional human biological matrices

NASA Astrophysics Data System (ADS)

Dutkiewicz, Ewelina P.; Urban, Pawel L.

2016-10-01

The development of sensitive and versatile mass spectrometric methodology has fuelled interest in the analysis of metabolites and drugs in unconventional biological specimens. Here, we discuss the analysis of eight human matrices-hair, nail, breath, saliva, tears, meibum, nasal mucus and skin excretions (including sweat)-by mass spectrometry (MS). The use of such specimens brings a number of advantages, the most important being non-invasive sampling, the limited risk of adulteration and the ability to obtain information that complements blood and urine tests. The most often studied matrices are hair, breath and saliva. This review primarily focuses on endogenous (e.g. potential biomarkers, hormones) and exogenous (e.g. drugs, environmental contaminants) small molecules. The majority of analytical methods used chromatographic separation prior to MS; however, such a hyphenated methodology greatly limits analytical throughput. On the other hand, the mass spectrometric methods that exclude chromatographic separation are fast but suffer from matrix interferences. To enable development of quantitative assays for unconventional matrices, it is desirable to standardize the protocols for the analysis of each specimen and create appropriate certified reference materials. Overcoming these challenges will make analysis of unconventional human biological matrices more common in a clinical setting. This article is part of the themed issue 'Quantitative mass spectrometry'.

Fast and Simple Discriminative Analysis of Anthocyanins-Containing Berries Using LC/MS Spectral Data.

PubMed

Yang, Heejung; Kim, Hyun Woo; Kwon, Yong Soo; Kim, Ho Kyong; Sung, Sang Hyun

2017-09-01

Anthocyanins are potent antioxidant agents that protect against many degenerative diseases; however, they are unstable because they are vulnerable to external stimuli including temperature, pH and light. This vulnerability hinders the quality control of anthocyanin-containing berries using classical high-performance liquid chromatography (HPLC) analytical methodologies based on UV or MS chromatograms. To develop an alternative approach for the quality assessment and discrimination of anthocyanin-containing berries, we used MS spectral data acquired in a short analytical time rather than UV or MS chromatograms. Mixtures of anthocyanins were separated from other components in a short gradient time (5 min) due to their higher polarity, and the representative MS spectrum was acquired from the MS chromatogram corresponding to the mixture of anthocyanins. The chemometric data from the representative MS spectra contained reliable information for the identification and relative quantification of anthocyanins in berries with good precision and accuracy. This fast and simple methodology, which consists of a simple sample preparation method and short gradient analysis, could be applied to reliably discriminate the species and geographical origins of different anthocyanin-containing berries. These features make the technique useful for the food industry. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

An Analytic Hierarchy Process for School Quality and Inspection: Model Development and Application

ERIC Educational Resources Information Center

Al Qubaisi, Amal; Badri, Masood; Mohaidat, Jihad; Al Dhaheri, Hamad; Yang, Guang; Al Rashedi, Asma; Greer, Kenneth

2016-01-01

Purpose: The purpose of this paper is to develop an analytic hierarchy planning-based framework to establish criteria weights and to develop a school performance system commonly called school inspections. Design/methodology/approach: The analytic hierarchy process (AHP) model uses pairwise comparisons and a measurement scale to generate the…

A Progressive Approach to Teaching Analytics in the Marketing Curriculum

ERIC Educational Resources Information Center

Liu, Yiyuan; Levin, Michael A.

2018-01-01

With the emerging use of analytics tools and methodologies in marketing, marketing educators have provided students training and experiences beyond the soft skills associated with understanding consumer behavior. Previous studies have only discussed how to apply analytics in course designs, tools, and related practices. However, there is a lack of…

Optimal designs for population pharmacokinetic studies of the partner drugs co-administered with artemisinin derivatives in patients with uncomplicated falciparum malaria.

PubMed

Jamsen, Kris M; Duffull, Stephen B; Tarning, Joel; Lindegardh, Niklas; White, Nicholas J; Simpson, Julie A

2012-07-11

Artemisinin-based combination therapy (ACT) is currently recommended as first-line treatment for uncomplicated malaria, but of concern, it has been observed that the effectiveness of the main artemisinin derivative, artesunate, has been diminished due to parasite resistance. This reduction in effect highlights the importance of the partner drugs in ACT and provides motivation to gain more knowledge of their pharmacokinetic (PK) properties via population PK studies. Optimal design methodology has been developed for population PK studies, which analytically determines a sampling schedule that is clinically feasible and yields precise estimation of model parameters. In this work, optimal design methodology was used to determine sampling designs for typical future population PK studies of the partner drugs (mefloquine, lumefantrine, piperaquine and amodiaquine) co-administered with artemisinin derivatives. The optimal designs were determined using freely available software and were based on structural PK models from the literature and the key specifications of 100 patients with five samples per patient, with one sample taken on the seventh day of treatment. The derived optimal designs were then evaluated via a simulation-estimation procedure. For all partner drugs, designs consisting of two sampling schedules (50 patients per schedule) with five samples per patient resulted in acceptable precision of the model parameter estimates. The sampling schedules proposed in this paper should be considered in future population pharmacokinetic studies where intensive sampling over many days or weeks of follow-up is not possible due to either ethical, logistic or economical reasons.

Analytical Methodology Used To Assess/Refine Observatory Thermal Vacuum Test Conditions For the Landsat 8 Data Continuity Mission

NASA Technical Reports Server (NTRS)

Fantano, Louis

2015-01-01

Thermal and Fluids Analysis Workshop Silver Spring, MD NCTS 21070-15 The Landsat 8 Data Continuity Mission, which is part of the United States Geologic Survey (USGS), launched February 11, 2013. A Landsat environmental test requirement mandated that test conditions bound worst-case flight thermal environments. This paper describes a rigorous analytical methodology applied to assess refine proposed thermal vacuum test conditions and the issues encountered attempting to satisfy this requirement.

Capillary Electrophoresis Sensitivity Enhancement Based on Adaptive Moving Average Method.

PubMed

Drevinskas, Tomas; Telksnys, Laimutis; Maruška, Audrius; Gorbatsova, Jelena; Kaljurand, Mihkel

2018-06-05

In the present work, we demonstrate a novel approach to improve the sensitivity of the "out of lab" portable capillary electrophoretic measurements. Nowadays, many signal enhancement methods are (i) underused (nonoptimal), (ii) overused (distorts the data), or (iii) inapplicable in field-portable instrumentation because of a lack of computational power. The described innovative migration velocity-adaptive moving average method uses an optimal averaging window size and can be easily implemented with a microcontroller. The contactless conductivity detection was used as a model for the development of a signal processing method and the demonstration of its impact on the sensitivity. The frequency characteristics of the recorded electropherograms and peaks were clarified. Higher electrophoretic mobility analytes exhibit higher-frequency peaks, whereas lower electrophoretic mobility analytes exhibit lower-frequency peaks. On the basis of the obtained data, a migration velocity-adaptive moving average algorithm was created, adapted, and programmed into capillary electrophoresis data-processing software. Employing the developed algorithm, each data point is processed depending on a certain migration time of the analyte. Because of the implemented migration velocity-adaptive moving average method, the signal-to-noise ratio improved up to 11 times for sampling frequency of 4.6 Hz and up to 22 times for sampling frequency of 25 Hz. This paper could potentially be used as a methodological guideline for the development of new smoothing algorithms that require adaptive conditions in capillary electrophoresis and other separation methods.

Multisyringe flow injection analysis hyphenated with liquid core waveguides for the development of cleaner spectroscopic analytical methods: improved determination of chloride in waters.

PubMed

Maya, Fernando; Estela, José Manuel; Cerdà, Víctor

2009-07-01

In this work, the hyphenation of the multisyringe flow injection analysis technique with a 100-cm-long pathlength liquid core waveguide has been accomplished. The Cl-/Hg(SCN)2/Fe3+ reaction system for the spectrophotometric determination of chloride (Cl(-)) in waters was used as chemical model. As a result, this classic analytical methodology has been improved, minimizing dramatically the consumption of reagents, in particular, that of the highly biotoxic chemical Hg(SCN)2. The proposed method features a linear dynamic range composed of two steps between (1) 0.2-2 and (2) 2-8 mg Cl- L(-1), thus extended applicability due to on-line sample dilution (up to 400 mg Cl- L(-1)). It also presents improved limits of detection and quantification of 0.06 and 0.20 mg Cl- L(-1), respectively. The coefficient of variation and the injection throughput were 1.3% (n = 10, 2 mg Cl- L(-1)) and 21 h(-1). Furthermore, a very low consumption of reagents per Cl- determination of 0.2 microg Hg(II) and 28 microg Fe3+ has been achieved. The method was successfully applied to the determination of Cl- in different types of water samples. Finally, the proposed system is critically compared from a green analytical chemistry point of view against other flow systems for the same purpose.

In vitro bioassays for detecting dioxin-like activity--application potentials and limits of detection, a review.

PubMed

Eichbaum, Kathrin; Brinkmann, Markus; Buchinger, Sebastian; Reifferscheid, Georg; Hecker, Markus; Giesy, John P; Engwall, Magnus; van Bavel, Bert; Hollert, Henner

2014-07-15

Use of in vitro assays as screening tool to characterize contamination of a variety of environmental matrices has become an increasingly popular and powerful toolbox in the field of environmental toxicology. While bioassays cannot entirely substitute analytical methods such as gas chromatography-mass spectrometry (GC-MS), the increasing improvement of cell lines and standardization of bioassay procedures enhance their utility as bioanalytical pre-screening tests prior to more targeted chemical analytical investigations. Dioxin-receptor-based assays provide a holistic characterization of exposure to dioxin-like compounds (DLCs) by integrating their overall toxic potential, including potentials of unknown DLCs not detectable via e.g. GC-MS. Hence, they provide important additional information with respect to environmental risk assessment of DLCs. This review summarizes different in vitro bioassay applications for detection of DLCs and considers the comparability of bioassay and chemical analytically derived toxicity equivalents (TEQs) of different approaches and various matrices. These range from complex samples such as sediments through single reference to compound mixtures. A summary of bioassay derived detection limits (LODs) showed a number of current bioassays to be equally sensitive as chemical methodologies, but moreover revealed that most of the bioanalytical studies conducted to date did not report their LODs, which represents a limitation with regard to low potency samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Current Technical Approaches for the Early Detection of Foodborne Pathogens: Challenges and Opportunities.

PubMed

Cho, Il-Hoon; Ku, Seockmo

2017-09-30

The development of novel and high-tech solutions for rapid, accurate, and non-laborious microbial detection methods is imperative to improve the global food supply. Such solutions have begun to address the need for microbial detection that is faster and more sensitive than existing methodologies (e.g., classic culture enrichment methods). Multiple reviews report the technical functions and structures of conventional microbial detection tools. These tools, used to detect pathogens in food and food homogenates, were designed via qualitative analysis methods. The inherent disadvantage of these analytical methods is the necessity for specimen preparation, which is a time-consuming process. While some literature describes the challenges and opportunities to overcome the technical issues related to food industry legal guidelines, there is a lack of reviews of the current trials to overcome technological limitations related to sample preparation and microbial detection via nano and micro technologies. In this review, we primarily explore current analytical technologies, including metallic and magnetic nanomaterials, optics, electrochemistry, and spectroscopy. These techniques rely on the early detection of pathogens via enhanced analytical sensitivity and specificity. In order to introduce the potential combination and comparative analysis of various advanced methods, we also reference a novel sample preparation protocol that uses microbial concentration and recovery technologies. This technology has the potential to expedite the pre-enrichment step that precedes the detection process.

Tennessee long-range transportation plan : project evaluation system

DOT National Transportation Integrated Search

2005-12-01

The Project Evaluation System (PES) Report is an analytical methodology to aid programming efforts and prioritize multimodal investments. The methodology consists of both quantitative and qualitative evaluation criteria built upon the Guiding Princip...

Towards automated human gait disease classification using phase space representation of intrinsic mode functions

NASA Astrophysics Data System (ADS)

Pratiher, Sawon; Patra, Sayantani; Pratiher, Souvik

2017-06-01

A novel analytical methodology for segregating healthy and neurological disorders from gait patterns is proposed by employing a set of oscillating components called intrinsic mode functions (IMF's). These IMF's are generated by the Empirical Mode Decomposition of the gait time series and the Hilbert transformed analytic signal representation forms the complex plane trace of the elliptical shaped analytic IMFs. The area measure and the relative change in the centroid position of the polygon formed by the Convex Hull of these analytic IMF's are taken as the discriminative features. Classification accuracy of 79.31% with Ensemble learning based Adaboost classifier validates the adequacy of the proposed methodology for a computer aided diagnostic (CAD) system for gait pattern identification. Also, the efficacy of several potential biomarkers like Bandwidth of Amplitude Modulation and Frequency Modulation IMF's and it's Mean Frequency from the Fourier-Bessel expansion from each of these analytic IMF's has been discussed for its potency in diagnosis of gait pattern identification and classification.

Extraction of toxic compounds from saliva by magnetic-stirring-assisted micro-solid-phase extraction step followed by headspace-gas chromatography-ion mobility spectrometry.

PubMed

Criado-García, Laura; Arce, Lourdes

2016-09-01

A new sample extraction procedure based on micro-solid-phase extraction (μSPE) using a mixture of sorbents of different polarities (polymeric reversed-phase sorbent HLB, silica-based sorbent C18, and multiwalled carbon nanotubes) was applied to extract benzene, toluene, butyraldehyde, benzaldehyde, and tolualdehyde present in saliva to avoid interference from moisture and matrix components and enhance sensitivity and selectivity of the ion mobility spectrometry (IMS) methodology proposed. The extraction of target analytes from saliva samples by using μSPE were followed by the desorption step carried out in the headspace vials placed in the autosampler of the IMS device. Then, 200 μL of headspace was injected into the GC column coupled to the IMS for its analysis. The method was fully validated in terms of sensitivity, precision, and recovery. The LODs and LOQs obtained, when analytes were dissolved in saliva samples to consider the matrix effect, were within the range of 0.38-0.49 and 1.26-1.66 μg mL(-1), respectively. The relative standard deviations were <3.5 % for retention time and drift time values, which indicate that the method proposed can be applied to determine toxic compounds in saliva samples. Graphical abstract Summary of steps followed in the experimental set up of this work.

Comparison of analytical methods for profiling N- and O-linked glycans from cultured cell lines

PubMed Central

Togayachi, Akira; Azadi, Parastoo; Ishihara, Mayumi; Geyer, Rudolf; Galuska, Christina; Geyer, Hildegard; Kakehi, Kazuaki; Kinoshita, Mitsuhiro; Karlsson, Niclas G.; Jin, Chunsheng; Kato, Koichi; Yagi, Hirokazu; Kondo, Sachiko; Kawasaki, Nana; Hashii, Noritaka; Kolarich, Daniel; Stavenhagen, Kathrin; Packer, Nicolle H.; Thaysen-Andersen, Morten; Nakano, Miyako; Taniguchi, Naoyuki; Kurimoto, Ayako; Wada, Yoshinao; Tajiri, Michiko; Yang, Pengyuan; Cao, Weiqian; Li, Hong; Rudd, Pauline M.; Narimatsu, Hisashi

2016-01-01

The Human Disease Glycomics/Proteome Initiative (HGPI) is an activity in the Human Proteome Organization (HUPO) supported by leading researchers from international institutes and aims at development of disease-related glycomics/glycoproteomics analysis techniques. Since 2004, the initiative has conducted three pilot studies. The first two were N- and O-glycan analyses of purified transferrin and immunoglobulin-G and assessed the most appropriate analytical approach employed at the time. This paper describes the third study, which was conducted to compare different approaches for quantitation of N- and O-linked glycans attached to proteins in crude biological samples. The preliminary analysis on cell pellets resulted in wildly varied glycan profiles, which was probably the consequence of variations in the pre-processing sample preparation methodologies. However, the reproducibility of the data was not improved dramatically in the subsequent analysis on cell lysate fractions prepared in a specified method by one lab. The study demonstrated the difficulty of carrying out a complete analysis of the glycome in crude samples by any single technology and the importance of rigorous optimization of the course of analysis from preprocessing to data interpretation. It suggests that another collaborative study employing the latest technologies in this rapidly evolving field will help to realize the requirements of carrying out the large-scale analysis of glycoproteins in complex cell samples. PMID:26511985

Single-step affinity purification of enzyme biotherapeutics: a platform methodology for accelerated process development.

PubMed

Brower, Kevin P; Ryakala, Venkat K; Bird, Ryan; Godawat, Rahul; Riske, Frank J; Konstantinov, Konstantin; Warikoo, Veena; Gamble, Jean

2014-01-01

Downstream sample purification for quality attribute analysis is a significant bottleneck in process development for non-antibody biologics. Multi-step chromatography process train purifications are typically required prior to many critical analytical tests. This prerequisite leads to limited throughput, long lead times to obtain purified product, and significant resource requirements. In this work, immunoaffinity purification technology has been leveraged to achieve single-step affinity purification of two different enzyme biotherapeutics (Fabrazyme® [agalsidase beta] and Enzyme 2) with polyclonal and monoclonal antibodies, respectively, as ligands. Target molecules were rapidly isolated from cell culture harvest in sufficient purity to enable analysis of critical quality attributes (CQAs). Most importantly, this is the first study that demonstrates the application of predictive analytics techniques to predict critical quality attributes of a commercial biologic. The data obtained using the affinity columns were used to generate appropriate models to predict quality attributes that would be obtained after traditional multi-step purification trains. These models empower process development decision-making with drug substance-equivalent product quality information without generation of actual drug substance. Optimization was performed to ensure maximum target recovery and minimal target protein degradation. The methodologies developed for Fabrazyme were successfully reapplied for Enzyme 2, indicating platform opportunities. The impact of the technology is significant, including reductions in time and personnel requirements, rapid product purification, and substantially increased throughput. Applications are discussed, including upstream and downstream process development support to achieve the principles of Quality by Design (QbD) as well as integration with bioprocesses as a process analytical technology (PAT). © 2014 American Institute of Chemical Engineers.

A dimensionless approach for the runoff peak assessment: effects of the rainfall event structure

NASA Astrophysics Data System (ADS)

Gnecco, Ilaria; Palla, Anna; La Barbera, Paolo

2018-02-01

The present paper proposes a dimensionless analytical framework to investigate the impact of the rainfall event structure on the hydrograph peak. To this end a methodology to describe the rainfall event structure is proposed based on the similarity with the depth-duration-frequency (DDF) curves. The rainfall input consists of a constant hyetograph where all the possible outcomes in the sample space of the rainfall structures can be condensed. Soil abstractions are modelled using the Soil Conservation Service method and the instantaneous unit hydrograph theory is undertaken to determine the dimensionless form of the hydrograph; the two-parameter gamma distribution is selected to test the proposed methodology. The dimensionless approach is introduced in order to implement the analytical framework to any study case (i.e. natural catchment) for which the model assumptions are valid (i.e. linear causative and time-invariant system). A set of analytical expressions are derived in the case of a constant-intensity hyetograph to assess the maximum runoff peak with respect to a given rainfall event structure irrespective of the specific catchment (such as the return period associated with the reference rainfall event). Looking at the results, the curve of the maximum values of the runoff peak reveals a local minimum point corresponding to the design hyetograph derived according to the statistical DDF curve. A specific catchment application is discussed in order to point out the dimensionless procedure implications and to provide some numerical examples of the rainfall structures with respect to observed rainfall events; finally their effects on the hydrograph peak are examined.

Sampling design for spatially distributed hydrogeologic and environmental processes

USGS Publications Warehouse

Christakos, G.; Olea, R.A.

1992-01-01

A methodology for the design of sampling networks over space is proposed. The methodology is based on spatial random field representations of nonhomogeneous natural processes, and on optimal spatial estimation techniques. One of the most important results of random field theory for physical sciences is its rationalization of correlations in spatial variability of natural processes. This correlation is extremely important both for interpreting spatially distributed observations and for predictive performance. The extent of site sampling and the types of data to be collected will depend on the relationship of subsurface variability to predictive uncertainty. While hypothesis formulation and initial identification of spatial variability characteristics are based on scientific understanding (such as knowledge of the physics of the underlying phenomena, geological interpretations, intuition and experience), the support offered by field data is statistically modelled. This model is not limited by the geometric nature of sampling and covers a wide range in subsurface uncertainties. A factorization scheme of the sampling error variance is derived, which possesses certain atttactive properties allowing significant savings in computations. By means of this scheme, a practical sampling design procedure providing suitable indices of the sampling error variance is established. These indices can be used by way of multiobjective decision criteria to obtain the best sampling strategy. Neither the actual implementation of the in-situ sampling nor the solution of the large spatial estimation systems of equations are necessary. The required values of the accuracy parameters involved in the network design are derived using reference charts (readily available for various combinations of data configurations and spatial variability parameters) and certain simple yet accurate analytical formulas. Insight is gained by applying the proposed sampling procedure to realistic examples related to sampling problems in two dimensions. ?? 1992.

Strategy for determination of LOD and LOQ values--some basic aspects.

PubMed

Uhrovčík, Jozef

2014-02-01

The paper is devoted to the evaluation of limit of detection (LOD) and limit of quantification (LOQ) values in concentration domain by using 4 different approaches; namely 3σ and 10σ approaches, ULA2 approach, PBA approach and MDL approach. Brief theoretical analyses of all above mentioned approaches are given together with directions for their practical use. Calculations and correct calibration design are exemplified by using of electrothermal atomic absorption spectrometry for determination of lead in drinking water sample. These validation parameters reached 1.6 μg L(-1) (LOD) and 5.4 μg L(-1) (LOQ) by using 3σ and 10σ approaches. For obtaining relevant values of analyte concentration the influence of calibration design and measurement methodology were examined. The most preferred technique has proven to be a method of preconcentration of the analyte on the surface of the graphite cuvette (boost cycle). © 2013 Elsevier B.V. All rights reserved.

Array-based sensing using nanoparticles: an alternative approach for cancer diagnostics.

PubMed

Le, Ngoc D B; Yazdani, Mahdieh; Rotello, Vincent M

2014-07-01

Array-based sensing using nanoparticles (NPs) provides an attractive alternative to specific biomarker-focused strategies for cancer diagnosis. The physical and chemical properties of NPs provide both the recognition and transduction capabilities required for biosensing. Array-based sensors utilize a combined response from the interactions between sensors and analytes to generate a distinct pattern (fingerprint) for each analyte. These interactions can be the result of either the combination of multiple specific biomarker recognition (specific binding) or multiple selective binding responses, known as chemical nose sensing. The versatility of the latter array-based sensing using NPs can facilitate the development of new personalized diagnostic methodologies in cancer diagnostics, a necessary evolution in the current healthcare system to better provide personalized treatments. This review will describe the basic principle of array-based sensors, along with providing examples of both invasive and noninvasive samples used in cancer diagnosis.

Multiple Reaction Monitoring Enables Precise Quantification of 97 Proteins in Dried Blood Spots*

PubMed Central

Chambers, Andrew G.; Percy, Andrew J.; Yang, Juncong; Borchers, Christoph H.

2015-01-01

The dried blood spot (DBS) methodology provides a minimally invasive approach to sample collection and enables room-temperature storage for most analytes. DBS samples have successfully been analyzed by liquid chromatography multiple reaction monitoring mass spectrometry (LC/MRM-MS) to quantify a large range of small molecule biomarkers and drugs; however, this strategy has only recently been explored for MS-based proteomics applications. Here we report the development of a highly multiplexed MRM assay to quantify endogenous proteins in human DBS samples. This assay uses matching stable isotope-labeled standard peptides for precise, relative quantification, and standard curves to characterize the analytical performance. A total of 169 peptides, corresponding to 97 proteins, were quantified in the final assay with an average linear dynamic range of 207-fold and an average R2 value of 0.987. The total range of this assay spanned almost 5 orders of magnitude from serum albumin (P02768) at 18.0 mg/ml down to cholinesterase (P06276) at 190 ng/ml. The average intra-assay and inter-assay precision for 6 biological samples ranged from 6.1–7.5% CV and 9.5–11.0% CV, respectively. The majority of peptide targets were stable after 154 days at storage temperatures from −20 °C to 37 °C. Furthermore, protein concentration ratios between matching DBS and whole blood samples were largely constant (<20% CV) across six biological samples. This assay represents the highest multiplexing yet achieved for targeted protein quantification in DBS samples and is suitable for biomedical research applications. PMID:26342038

Thawing as a critical pre-analytical step in the lipidomic profiling of plasma samples: New standardized protocol.

PubMed

Pizarro, Consuelo; Arenzana-Rámila, Irene; Pérez-del-Notario, Nuria; Pérez-Matute, Patricia; González-Sáiz, José María

2016-03-17

Lipid profiling is a promising tool for the discovery and subsequent identification of biomarkers associated with various diseases. However, data quality is quite dependent on the pre-analytical methods employed. To date, potential confounding factors that may affect lipid metabolite levels after the thawing of plasma for biomarker exploration studies have not been thoroughly evaluated. In this study, by means of experimental design methodology, we performed the first in-depth examination of the ways in which thawing conditions affect lipid metabolite levels. After the optimization stage, we concluded that temperature, sample volume and the thawing method were the determining factors that had to be exhaustively controlled in the thawing process to ensure the quality of biomarker discovery. Best thawing conditions were found to be: 4 °C, with 0.25 mL of human plasma and ultrasound (US) thawing. The new US proposed thawing method was quicker than the other methods we studied, allowed more features to be identified and increased the signal of the lipids. In view of its speed, efficiency and detectability, the US thawing method appears to be a simple, economical method for the thawing of plasma samples, which could easily be applied in clinical laboratories before lipid profiling studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an analytical method for antimony speciation in vegetables by HPLC-hydride generation-atomic fluorescence spectrometry.

PubMed

Olivares, David; Bravo, Manuel; Feldmann, Jorg; Raab, Andrea; Neaman, Alexander; Quiroz, Waldo

2012-01-01

A new method for antimony speciation in terrestrial edible vegetables (spinach, onions, and carrots) was developed using HPLC with hydride generation-atomic fluorescence spectrometry. Mechanical agitation and ultrasound were tested as extraction techniques. Different extraction reagents were evaluated and optimal conditions were determined using experimental design methodology, where EDTA (10 mmol/L, pH 2.5) was selected because this chelate solution produced the highest extraction yield and exhibited the best compatibility with the mobile phase. The results demonstrated that EDTA prevents oxidation of Sb(III) to Sb(V) and maintains the stability of antimony species during the entire analytical process. The LOD and precision (RSD values obtained) for Sb(V), Sb(III), and trimethyl Sb(V) were 0.08, 0.07, and 0.9 microg/L and 5.0, 5.2, and 4.7%, respectively, for a 100 microL sample volume. The application of this method to real samples allowed extraction of 50% of total antimony content from spinach, while antimony extracted from carrots and onion samples ranged between 50 and 60 and 54 and 70%, respectively. Only Sb(V) was detected in three roots (onion and spinach) that represented 60-70% of the total antimony in the extracts.

A dispersive liquid--liquid microextraction methodology for copper (II) in environmental samples prior to determination using microsample injection flame atomic absorption spectrometry.

PubMed

Alothman, Zeid A; Habila, Mohamed; Yilmaz, Erkan; Soylak, Mustafa

2013-01-01

A simple, environmentally friendly, and efficient dispersive liquid-liquid microextraction method combined with microsample injection flame atomic absorption spectrometry was developed for the separation and preconcentration of Cu(II). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was used to form a hydrophobic complex of Cu(II) ions in the aqueous phase before extraction. To extract the Cu(II)-5-Br-PADAP complex from the aqueous phase to the organic phase, 2.0 mL of acetone as a disperser solvent and 200 microL of chloroform as an extraction solvent were used. The influences of important analytical parameters, such as the pH, types and volumes of the extraction and disperser solvents, amount of chelating agent, sample volume, and matrix effects, on the microextraction procedure were evaluated and optimized. Using the optimal conditions, the LOD, LOQ, preconcentration factor, and RSD were determined to be 1.4 microg/L, 4.7 microg/L, 120, and 6.5%, respectively. The accuracy of the proposed method was investigated using standard addition/recovery tests. The analysis of certified reference materials produced satisfactory analytical results. The developed method was applied for the determination of Cu in real samples.

Aluminium sensitized spectrofluorimetric determination of fluoroquinolones in milk samples coupled with salting-out assisted liquid-liquid ultrasonic extraction

NASA Astrophysics Data System (ADS)

Xia, Qinghai; Yang, Yaling; Liu, Mousheng

2012-10-01

An aluminium sensitized spectrofluorimetric method coupled with salting-out assisted liquid-liquid ultrasonic extraction for the determination of four widely used fluoroquinolones (FQs) namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in bovine raw milk was described. The analytical procedure involves the fluorescence sensitization of aluminium (Al3+) by complexation with FQs, salting-out assisted liquid-liquid ultrasonic extraction (SALLUE), followed by spectrofluorometry. The influence of several parameters on the extraction (the salt species, the amount of salt, pH, temperature and phase volume ratio) was investigated. Under optimized experimental conditions, the detection limits of the method in milk varied from 0.009 μg/mL for NOR to 0.016 μg/mL for GAT (signal-to-noise ratio (S/N) = 3). The relative standard deviations (RSD) values were found to be relatively low (0.54-2.48% for four compounds). The calibration graph was linear from 0.015 to 2.25 μg/mL with coefficient of determinations not less than 0.9974. The methodology developed was applied to the determination of FQs in bovine raw milk samples. The main advantage of this method is simple, accurate and green. The method showed promising applications for analyzing polar analytes especially polar drugs in various sample matrices.

Development of a Terbium-Sensitized Fluorescence Method for Analysis of Silibinin.

PubMed

Ershadi, Saba; Jouyban, Abolghasem; Molavi, Ommoleila; Shayanfar, Ali

2017-05-01

Silibinin is a natural flavonoid with potent anticancer properties, as shown in both in vitro and in vivo experiments. Various methods have been used for silibinin analysis. Terbium-sensitized fluorescence methods have been widely used for the determination of drugs in pharmaceutical preparations and biological samples in recent years. The present work is aimed at providing a simple analytical method for the quantitative determination of silibinin in aqueous solutions based on the formation of a fluorescent complex with terbium ion. Terbium concentration, pH, and volume of buffer, the important effective parameters for the determination of silibinin by the proposed method, were optimized using response surface methodology. The fluorescence intensity of silibinin was measured at 545 nm using λex = 334 nm. The developed method was applied for the determination of silibinin in plasma samples after protein precipitation with acetone. Under optimum conditions, the method provided a linear range between 0.10 and 0.50 mg/L, with a coefficient of determination (R2) of 0.997. The LOD and LOQ were 0.034 and 0.112 mg/L, respectively. These results indicate that the developed method is a simple, low-cost, and suitable analytical method for the quantification of silibinin in aqueous solution and plasma samples.

Two-dimensional fingerprinting approach for comparison of complex substances analysed by HPLC-UV and fluorescence detection.

PubMed

Ni, Yongnian; Liu, Ying; Kokot, Serge

2011-02-07

This work is concerned with the research and development of methodology for analysis of complex mixtures such as pharmaceutical or food samples, which contain many analytes. Variously treated samples (swill washed, fried and scorched) of the Rhizoma atractylodis macrocephalae (RAM) traditional Chinese medicine (TCM) as well as the common substitute, Rhizoma atractylodis (RA) TCM were chosen as examples for analysis. A combined data matrix of chromatographic 2-D HPLC-DAD-FLD (two-dimensional high performance liquid chromatography with diode array and fluorescence detectors) fingerprint profiles was constructed with the use of the HPLC-DAD and HPLC-FLD individual data matrices; the purpose was to collect maximum information and to interpret this complex data with the use of various chemometrics methods e.g. the rank-ordering multi-criteria decision making (MCDM) PROMETHEE and GAIA, K-nearest neighbours (KNN), partial least squares (PLS), back propagation-artificial neural networks (BP-ANN) methods. The chemometrics analysis demonstrated that the combined 2-D HPLC-DAD-FLD data matrix does indeed provide more information and facilitates better performing classification/prediction models for the analysis of such complex samples as the RAM and RA ones noted above. It is suggested that this fingerprint approach is suitable for analysis of other complex, multi-analyte substances.

A shipboard comparison of analytic methods for ballast water compliance monitoring

NASA Astrophysics Data System (ADS)

Bradie, Johanna; Broeg, Katja; Gianoli, Claudio; He, Jianjun; Heitmüller, Susanne; Curto, Alberto Lo; Nakata, Akiko; Rolke, Manfred; Schillak, Lothar; Stehouwer, Peter; Vanden Byllaardt, Julie; Veldhuis, Marcel; Welschmeyer, Nick; Younan, Lawrence; Zaake, André; Bailey, Sarah

2018-03-01

Promising approaches for indicative analysis of ballast water samples have been developed that require study in the field to examine their utility for determining compliance with the International Convention for the Control and Management of Ships' Ballast Water and Sediments. To address this gap, a voyage was undertaken on board the RV Meteor, sailing the North Atlantic Ocean from Mindelo (Cape Verde) to Hamburg (Germany) during June 4-15, 2015. Trials were conducted on local sea water taken up by the ship's ballast system at multiple locations along the trip, including open ocean, North Sea, and coastal water, to evaluate a number of analytic methods that measure the numeric concentration or biomass of viable organisms according to two size categories (≥ 50 μm in minimum dimension: 7 techniques, ≥ 10 μm and < 50 μm: 9 techniques). Water samples were analyzed in parallel to determine whether results were similar between methods and whether rapid, indicative methods offer comparable results to standard, time- and labor-intensive detailed methods (e.g. microscopy) and high-end scientific approaches (e.g. flow cytometry). Several promising indicative methods were identified that showed high correlation with microscopy, but allow much quicker processing and require less expert knowledge. This study is the first to concurrently use a large number of analytic tools to examine a variety of ballast water samples on board an operational ship in the field. Results are useful to identify the merits of each method and can serve as a basis for further improvement and development of tools and methodologies for ballast water compliance monitoring.

Headspace gas chromatography based methodology for the analysis of aromatic substituted quaternary ammonium salts.

PubMed

van Boxtel, Niels; Wolfs, Kris; Palacín, Marta Guillén; Van Schepdael, Ann; Adams, Erwin

2016-12-09

The analysis of quaternary ammonium salts (QAS) using GC is often performed by "in injector" pyrolysis to create volatile degradation products for quantification purposes. Besides the risk of severe system contamination, the application of this approach on aqueous samples is problematic. In this work, the sample is treated in a vial with 2,2-dimethoxypropane (DMP) under acidic catalysis. In addition to the removal of water and sample enrichment, the QAS are decomposed. As HS transfers only volatile compounds to the GC system, contamination is avoided. It was found that depending on the presence of benzyl, phenyl or methyl groups on the quaternary nitrogen; benzyl chloride, N,N-dimethylaniline or chloromethane are formed respectively in the sealed vial. All these can be used as an analytical target. A calibration curve for benzyl chloride could be derived from the pure compound. Chloromethane was generated from pure benzyldimethyldecylammonium chloride (BEDIDE), a pure QAS with benzyl and methyl groups, to construct a secondary calibration curve using a back analysis approach. It has been proven that by quantifying the formed analytical targets, the mass balance for the QAS under investigation was close to 100%. The presented procedure allows the quantification of any aromatic substituted QAS without the need for a matching reference, which is a major advantage over existing CE and LC methods The proposed methodology was validated for mouth sprays containing benzethonium chloride (BZTCl) or benzoxonium chloride (BZOCl) and for denatonium benzoate (DB) in ethylene glycol (EG) based cooling liquids. Results showed that the approach provided excellent linearity (R 2 ≥0.999) and limits of detection around 0.01μg/vial for benzyl chloride. It was found that the reaction product of DMP and glycerol which was also present in the mouthspray and some cooling liquids, caused chromatographic interference with benzyl chloride. Treating those samples in the vial with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) after the enrichment step removes the interference and leaves a possible pathway for the simultaneous determination of glycerol in those samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Prevalence of Pre-Analytical Errors in Clinical Chemistry Diagnostic Labs in Sulaimani City of Iraqi Kurdistan

PubMed Central

2017-01-01

Background Laboratory testing is roughly divided into three phases: a pre-analytical phase, an analytical phase and a post-analytical phase. Most analytical errors have been attributed to the analytical phase. However, recent studies have shown that up to 70% of analytical errors reflect the pre-analytical phase. The pre-analytical phase comprises all processes from the time a laboratory request is made by a physician until the specimen is analyzed at the lab. Generally, the pre-analytical phase includes patient preparation, specimen transportation, specimen collection and storage. In the present study, we report the first comprehensive assessment of the frequency and types of pre-analytical errors at the Sulaimani diagnostic labs in Iraqi Kurdistan. Materials and Methods Over 2 months, 5500 venous blood samples were observed in 10 public diagnostic labs of Sulaimani City. The percentages of rejected samples and types of sample inappropriateness were evaluated. The percentage of each of the following pre-analytical errors were recorded: delay in sample transportation, clotted samples, expired reagents, hemolyzed samples, samples not on ice, incorrect sample identification, insufficient sample, tube broken in centrifuge, request procedure errors, sample mix-ups, communication conflicts, misinterpreted orders, lipemic samples, contaminated samples and missed physician’s request orders. The difference between the relative frequencies of errors observed in the hospitals considered was tested using a proportional Z test. In particular, the survey aimed to discover whether analytical errors were recorded and examine the types of platforms used in the selected diagnostic labs. Results The analysis showed a high prevalence of improper sample handling during the pre-analytical phase. In appropriate samples, the percentage error was as high as 39%. The major reasons for rejection were hemolyzed samples (9%), incorrect sample identification (8%) and clotted samples (6%). Most quality control schemes at Sulaimani hospitals focus only on the analytical phase, and none of the pre-analytical errors were recorded. Interestingly, none of the labs were internationally accredited; therefore, corrective actions are needed at these hospitals to ensure better health outcomes. Internal and External Quality Assessment Schemes (EQAS) for the pre-analytical phase at Sulaimani clinical laboratories should be implemented at public hospitals. Furthermore, lab personnel, particularly phlebotomists, need continuous training on the importance of sample quality to obtain accurate test results. PMID:28107395

Prevalence of Pre-Analytical Errors in Clinical Chemistry Diagnostic Labs in Sulaimani City of Iraqi Kurdistan.

PubMed

Najat, Dereen

2017-01-01

Laboratory testing is roughly divided into three phases: a pre-analytical phase, an analytical phase and a post-analytical phase. Most analytical errors have been attributed to the analytical phase. However, recent studies have shown that up to 70% of analytical errors reflect the pre-analytical phase. The pre-analytical phase comprises all processes from the time a laboratory request is made by a physician until the specimen is analyzed at the lab. Generally, the pre-analytical phase includes patient preparation, specimen transportation, specimen collection and storage. In the present study, we report the first comprehensive assessment of the frequency and types of pre-analytical errors at the Sulaimani diagnostic labs in Iraqi Kurdistan. Over 2 months, 5500 venous blood samples were observed in 10 public diagnostic labs of Sulaimani City. The percentages of rejected samples and types of sample inappropriateness were evaluated. The percentage of each of the following pre-analytical errors were recorded: delay in sample transportation, clotted samples, expired reagents, hemolyzed samples, samples not on ice, incorrect sample identification, insufficient sample, tube broken in centrifuge, request procedure errors, sample mix-ups, communication conflicts, misinterpreted orders, lipemic samples, contaminated samples and missed physician's request orders. The difference between the relative frequencies of errors observed in the hospitals considered was tested using a proportional Z test. In particular, the survey aimed to discover whether analytical errors were recorded and examine the types of platforms used in the selected diagnostic labs. The analysis showed a high prevalence of improper sample handling during the pre-analytical phase. In appropriate samples, the percentage error was as high as 39%. The major reasons for rejection were hemolyzed samples (9%), incorrect sample identification (8%) and clotted samples (6%). Most quality control schemes at Sulaimani hospitals focus only on the analytical phase, and none of the pre-analytical errors were recorded. Interestingly, none of the labs were internationally accredited; therefore, corrective actions are needed at these hospitals to ensure better health outcomes. Internal and External Quality Assessment Schemes (EQAS) for the pre-analytical phase at Sulaimani clinical laboratories should be implemented at public hospitals. Furthermore, lab personnel, particularly phlebotomists, need continuous training on the importance of sample quality to obtain accurate test results.

MS-based analytical methodologies to characterize genetically modified crops.

PubMed

García-Cañas, Virginia; Simó, Carolina; León, Carlos; Ibáñez, Elena; Cifuentes, Alejandro

2011-01-01

The development of genetically modified crops has had a great impact on the agriculture and food industries. However, the development of any genetically modified organism (GMO) requires the application of analytical procedures to confirm the equivalence of the GMO compared to its isogenic non-transgenic counterpart. Moreover, the use of GMOs in foods and agriculture faces numerous criticisms from consumers and ecological organizations that have led some countries to regulate their production, growth, and commercialization. These regulations have brought about the need of new and more powerful analytical methods to face the complexity of this topic. In this regard, MS-based technologies are increasingly used for GMOs analysis to provide very useful information on GMO composition (e.g., metabolites, proteins). This review focuses on the MS-based analytical methodologies used to characterize genetically modified crops (also called transgenic crops). First, an overview on genetically modified crops development is provided, together with the main difficulties of their analysis. Next, the different MS-based analytical approaches applied to characterize GM crops are critically discussed, and include "-omics" approaches and target-based approaches. These methodologies allow the study of intended and unintended effects that result from the genetic transformation. This information is considered to be essential to corroborate (or not) the equivalence of the GM crop with its isogenic non-transgenic counterpart. Copyright © 2010 Wiley Periodicals, Inc.

Dried Blood Spot Methodology in Combination With Liquid Chromatography/Tandem Mass Spectrometry Facilitates the Monitoring of Teriflunomide

PubMed Central

Lunven, Catherine; Turpault, Sandrine; Beyer, Yann-Joel; O'Brien, Amy; Delfolie, Astrid; Boyanova, Neli; Sanderink, Ger-Jan; Baldinetti, Francesca

2016-01-01

Background: Teriflunomide, a once-daily oral immunomodulator approved for treatment of relapsing-remitting multiple sclerosis, is eliminated slowly from plasma. If necessary to rapidly lower plasma concentrations of teriflunomide, an accelerated elimination procedure using cholestyramine or activated charcoal may be used. The current bioanalytical assay for determination of plasma teriflunomide concentration requires laboratory facilities for blood centrifugation and plasma storage. An alternative method, with potential for greater convenience, is dried blood spot (DBS) methodology. Analytical and clinical validations are required to switch from plasma to DBS (finger-prick sampling) methodology. Methods: Using blood samples from healthy subjects, an LC-MS/MS assay method for quantification of teriflunomide in DBS over a range of 0.01–10 mcg/mL was developed and validated for specificity, selectivity, accuracy, precision, reproducibility, and stability. Results were compared with those from the current plasma assay for determination of plasma teriflunomide concentration. Results: Method was specific and selective relative to endogenous compounds, with process efficiency ∼88%, and no matrix effect. Inaccuracy and imprecision for intraday and interday analyses were <15% at all concentrations tested. Quantification of teriflunomide in DBS assay was not affected by blood deposit volume and punch position within spot, and hematocrit level had a limited but acceptable effect on measurement accuracy. Teriflunomide was stable for at least 4 months at room temperature, and for at least 24 hours at 37°C with and without 95% relative humidity, to cover sampling, drying, and shipment conditions in the field. The correlation between DBS and plasma concentrations (R2 = 0.97), with an average blood to plasma ratio of 0.59, was concentration independent and constant over time. Conclusions: DBS sampling is a simple and practical method for monitoring teriflunomide concentrations. PMID:27015245

Multicriteria decision analysis in ranking of analytical procedures for aldrin determination in water.

PubMed

Tobiszewski, Marek; Orłowski, Aleksander

2015-03-27

The study presents the possibility of multi-criteria decision analysis (MCDA) application when choosing analytical procedures with low environmental impact. A type of MCDA, Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE), was chosen as versatile tool that meets all the analytical chemists--decision makers requirements. Twenty five analytical procedures for aldrin determination in water samples (as an example) were selected as input alternatives to MCDA analysis. Nine different criteria describing the alternatives were chosen from different groups--metrological, economical and the most importantly--environmental impact. The weights for each criterion were obtained from questionnaires that were sent to experts, giving three different scenarios for MCDA results. The results of analysis show that PROMETHEE is very promising tool to choose the analytical procedure with respect to its greenness. The rankings for all three scenarios placed solid phase microextraction and liquid phase microextraction--based procedures high, while liquid-liquid extraction, solid phase extraction and stir bar sorptive extraction--based procedures were placed low in the ranking. The results show that although some of the experts do not intentionally choose green analytical chemistry procedures, their MCDA choice is in accordance with green chemistry principles. The PROMETHEE ranking results were compared with more widely accepted green analytical chemistry tools--NEMI and Eco-Scale. As PROMETHEE involved more different factors than NEMI, the assessment results were only weakly correlated. Oppositely, the results of Eco-Scale assessment were well-correlated as both methodologies involved similar criteria of assessment. Copyright © 2015 Elsevier B.V. All rights reserved.

Validation of metabolomics analysis of human perilymph fluid using liquid chromatography-mass spectroscopy.

PubMed

Mavel, Sylvie; Lefèvre, Antoine; Bakhos, David; Dufour-Rainfray, Diane; Blasco, Hélène; Emond, Patrick

2018-05-22

Although there is some data from animal studies, the metabolome of inner ear fluid in humans remains unknown. Characterization of the metabolome of the perilymph would allow for better understanding of its role in auditory function and for identification of biomarkers that might allow prediction of response to therapeutics. There is a major technical challenge due to the small sample of perilymph fluid available for analysis (sub-microliter). The objectives of this study were to develop and validate a methodology for analysis of perilymph metabolome using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Due to the low availability of perilymph fluid; a methodological study was first performed using low volumes (0.8 μL) of cerebrospinal fluid (CSF) and optimized the LC-HRMS parameters using targeted and non-targeted metabolomics approaches. We obtained excellent parameters of reproducibility for about 100 metabolites. This methodology was then used to analyze perilymph fluid using two complementary chromatographic supports: reverse phase (RP-C18) and hydrophilic interaction liquid chromatography (HILIC). Both methods were highly robust and showed their complementarity, thus reinforcing the interest to combine these chromatographic supports. A fingerprinting was obtained from 98 robust metabolites (analytical variability <30%), where amino acids (e.g., asparagine, valine, glutamine, alanine, etc.), carboxylic acids and derivatives (e.g., lactate, carnitine, trigonelline, creatinine, etc.) were observed as first-order signals. This work lays the foundations of a robust analytical workflow for the exploration of the perilymph metabolome dedicated to the research of biomarkers for the diagnosis/prognosis of auditory pathologies. Copyright © 2018 Elsevier B.V. All rights reserved.

Durability predictions of adhesively bonded composite structures using accelerated characterization methods

NASA Technical Reports Server (NTRS)

Brinson, H. F.

1985-01-01

The utilization of adhesive bonding for composite structures is briefly assessed. The need for a method to determine damage initiation and propagation for such joints is outlined. Methods currently in use to analyze both adhesive joints and fiber reinforced plastics is mentioned and it is indicated that all methods require the input of the mechanical properties of the polymeric adhesive and composite matrix material. The mechanical properties of polymers are indicated to be viscoelastic and sensitive to environmental effects. A method to analytically characterize environmentally dependent linear and nonlinear viscoelastic properties is given. It is indicated that the methodology can be used to extrapolate short term data to long term design lifetimes. That is, the method can be used for long term durability predictions. Experimental results for near adhesive resins, polymers used as composite matrices and unidirectional composite laminates is given. The data is fitted well with the analytical durability methodology. Finally, suggestions are outlined for the development of an analytical methodology for the durability predictions of adhesively bonded composite structures.

Combining numerical simulations with time-domain random walk for pathogen risk assessment in groundwater

NASA Astrophysics Data System (ADS)

Cvetkovic, V.; Molin, S.

2012-02-01

We present a methodology that combines numerical simulations of groundwater flow and advective transport in heterogeneous porous media with analytical retention models for computing the infection risk probability from pathogens in aquifers. The methodology is based on the analytical results presented in [1,2] for utilising the colloid filtration theory in a time-domain random walk framework. It is shown that in uniform flow, the results from the numerical simulations of advection yield comparable results as the analytical TDRW model for generating advection segments. It is shown that spatial variability of the attachment rate may be significant, however, it appears to affect risk in a different manner depending on if the flow is uniform or radially converging. In spite of the fact that numerous issues remain open regarding pathogen transport in aquifers on the field scale, the methodology presented here may be useful for screening purposes, and may also serve as a basis for future studies that would include greater complexity.

An evaluation of benthic macroinvertebrate biomass methodology : Part 1. Laboratory analytical methods.

PubMed

Mason, W T; Lewis, P A; Weber, C I

1983-03-01

Evaluation of analytical methods employed for wet weight (live or preserved samples) of benthic macroinvertebrates reveals that centrifugation at 140 x gravity for one minute yields constant biomass estimates. Less relative centrifugal force increases chance of incomplete removal of body moisture and results in weighing error, while greater force may rupture fragile macroinvertebrates, such as mayflies. Duration of specimen exposure in ethanol, formalin, and formol (formaling-ethanol combinations) causes significant body weight loss with within 48 hr formalin and formol cause less body weight loss than ethanol. However, as all preservatives tested cause body weight loss, preservation time of samples collected for comparative purposes should be treated uniformly. Dry weight estimates of macroinvertebrates are not significantly affected by kind of preservative or duration of exposure. Constant dry weights are attained by oven drying at 103 °C at a minimum of four hours or vacuum oven drying (15 inches of mercury pressure) at 103 °C for a minimum of one hour. Although requiring more time in preparation than oven drying and inalterably changing specimen body shape, freeze drying (10 microns pressure, -55 °C, 24 hr) provides constant dry weights and is advantageous for long term sample storage by minimizing curatorial attention. Constant ash-free dry weights of macroinvertebrate samples are attained by igniting samples at 500-550 °C for a minimum of one hour with slow cooling to room temperature in desiccators before weighing.

Novel combination of non-aqueous capillary electrophoresis and multivariate curve resolution-alternating least squares to determine phenolic acids in virgin olive oil.

PubMed

Godoy-Caballero, María del Pilar; Culzoni, María Julia; Galeano-Díaz, Teresa; Acedo-Valenzuela, María Isabel

2013-02-06

This paper presents the development of a non-aqueous capillary electrophoresis method coupled to UV detection combined with multivariate curve resolution-alternating least-squares (MCR-ALS) to carry out the resolution and quantitation of a mixture of six phenolic acids in virgin olive oil samples. p-Coumaric, caffeic, ferulic, 3,4-dihydroxyphenylacetic, vanillic and 4-hydroxyphenilacetic acids have been the analytes under study. All of them present different absorption spectra and overlapped time profiles with the olive oil matrix interferences and between them. The modeling strategy involves the building of a single MCR-ALS model composed of matrices augmented in the temporal mode, namely spectra remain invariant while time profiles may change from sample to sample. So MCR-ALS was used to cope with the coeluting interferences, on accounting the second order advantage inherent to this algorithm which, in addition, is able to handle data sets deviating from trilinearity, like the data herein analyzed. The method was firstly applied to resolve standard mixtures of the analytes randomly prepared in 1-propanol and, secondly, in real virgin olive oil samples, getting recovery values near to 100% in all cases. The importance and novelty of this methodology relies on the combination of non-aqueous capillary electrophoresis second-order data and MCR-ALS algorithm which allows performing the resolution of these compounds simplifying the previous sample pretreatment stages. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of pyridostigmine bromide and its metabolites in biological samples.

PubMed

Zhao, Bin; Moochhala, Shabbir M; Lu, Jia; Tan, Donna; Lai, Mui Hoon

2006-01-01

Pyridostigmine bromide (PB) is a quartenary ammonium compound that inhibits the hydrolysis of acetylcholine by competitive reversible binding to acetylcholinesterase. PB is used for the symptomatic treatment of myasthenia gravis and has been applied as a prophylaxis against nerve agents. Many studies on PB have involved the reliance on techniques that extract and quantify PB in biological samples. This article presents an overview of the currently applied methodologies for the determination of PB and its metabolites in various biological samples. Articles published from January 1975 to the July 2005 were taken into consideration for the discussion of the metabolism and analytical method of PB. HPLC and GC methods have been used and discussed in most of the references cited in this review. Other methods such as RIA and CE that have been recently reported are also mentioned in this article. Basic information about the type of sample used for analysis, sample preparation, chromatographic column, mobile phase, detection mode and validation data are summarized in a table.

Integrated corridor management analysis, modeling and simulation (AMS) methodology.

DOT National Transportation Integrated Search

2008-03-01

This AMS Methodologies Document provides a discussion of potential ICM analytical approaches for the assessment of generic corridor operations. The AMS framework described in this report identifies strategies and procedures for tailoring AMS general ...

[Management of pre-analytical nonconformities].

PubMed

Berkane, Z; Dhondt, J L; Drouillard, I; Flourié, F; Giannoli, J M; Houlbert, C; Surgat, P; Szymanowicz, A

2010-12-01

The main nonconformities enumerated to facilitate consensual codification. In each case, an action is defined: refusal to realize the examination with request of a new sample, request of information or correction, results cancellation, nurse or physician information. A traceability of the curative, corrective and preventive actions is needed. Then, methodology and indicators are proposed to assess nonconformity and to follow the quality improvements. The laboratory information system can be used instead of dedicated software. Tools for the follow-up of nonconformities scores are proposed. Finally, we propose an organization and some tools allowing the management and control of the nonconformities occurring during the pre-examination phase.

Construcción de un catálogo de cúmulos de galaxias en proceso de colisión

NASA Astrophysics Data System (ADS)

de los Ríos, M.; Domínguez, M. J.; Paz, D.

2015-08-01

In this work we present first results of the identification of colliding galaxy clusters in galaxy catalogs with redshift measurements (SDSS, 2DF), and introduce the methodology. We calibrated a method by studying the merger trees of clusters in a mock catalog based on a full-blown semi-analytic model of galaxy formation on top of the Millenium cosmological simulation. We also discuss future actions for studding our sample of colliding galaxy clusters, including x-ray observations and mass reconstruction obtained by using weak gravitational lenses.

Safety of High Speed Ground Transportation Systems : Analytical Methodology for Safety Validation of Computer Controlled Subsystems : Volume 2. Development of a Safety Validation Methodology

DOT National Transportation Integrated Search

1995-01-01

This report describes the development of a methodology designed to assure that a sufficiently high level of safety is achieved and maintained in computer-based systems which perform safety cortical functions in high-speed rail or magnetic levitation ...

Analytical methodology for safety validation of computer controlled subsystems. Volume 1 : state-of-the-art and assessment of safety verification/validation methodologies

DOT National Transportation Integrated Search

1995-09-01

This report describes the development of a methodology designed to assure that a sufficiently high level of safety is achieved and maintained in computer-based systems which perform safety critical functions in high-speed rail or magnetic levitation ...

Analytical Electrochemistry: Methodology and Applications of Dynamic Techniques.

ERIC Educational Resources Information Center

Heineman, William R.; Kissinger, Peter T.

1980-01-01

Reports developments involving the experimental aspects of finite and current analytical electrochemistry including electrode materials (97 cited references), hydrodynamic techniques (56), spectroelectrochemistry (62), stripping voltammetry (70), voltammetric techniques (27), polarographic techniques (59), and miscellany (12). (CS)

Building a Three-Dimensional Nano-Bio Interface for Aptasensing: An Analytical Methodology Based on Steric Hindrance Initiated Signal Amplification Effect.

PubMed

Du, Xiaojiao; Jiang, Ding; Hao, Nan; Qian, Jing; Dai, Liming; Zhou, Lei; Hu, Jianping; Wang, Kun

2016-10-04

The development of novel detection methodologies in electrochemiluminescence (ECL) aptasensor fields with simplicity and ultrasensitivity is essential for constructing biosensing architectures. Herein, a facile, specific, and sensitive methodology was developed unprecedentedly for quantitative detection of microcystin-LR (MC-LR) based on three-dimensional boron and nitrogen codoped graphene hydrogels (BN-GHs) assisted steric hindrance amplifying effect between the aptamer and target analytes. The recognition reaction was monitored by quartz crystal microbalance (QCM) to validate the possible steric hindrance effect. First, the BN-GHs were synthesized via self-assembled hydrothermal method and then applied as the Ru(bpy) 3 2+ immobilization platform for further loading the biomolecule aptamers due to their nanoporous structure and large specific surface area. Interestingly, we discovered for the first time that, without the aid of conventional double-stranded DNA configuration, such three-dimensional nanomaterials can directly amplify the steric hindrance effect between the aptamer and target analytes to a detectable level, and this facile methodology could be for an exquisite assay. With the MC-LR as a model, this novel ECL biosensor showed a high sensitivity and a wide linear range. This strategy supplies a simple and versatile platform for specific and sensitive determination of a wide range of aptamer-related targets, implying that three-dimensional nanomaterials would play a crucial role in engineering and developing novel detection methodologies for ECL aptasensing fields.

Violent Video Game Effects on Aggression, Empathy, and Prosocial Behavior in Eastern and Western Countries: A Meta-Analytic Review

ERIC Educational Resources Information Center

Anderson, Craig A.; Shibuya, Akiko; Ihori, Nobuko; Swing, Edward L.; Bushman, Brad J.; Sakamoto, Akira; Rothstein, Hannah R.; Saleem, Muniba

2010-01-01

Meta-analytic procedures were used to test the effects of violent video games on aggressive behavior, aggressive cognition, aggressive affect, physiological arousal, empathy/desensitization, and prosocial behavior. Unique features of this meta-analytic review include (a) more restrictive methodological quality inclusion criteria than in past…

Guidelines for reporting methodological challenges and evaluating potential bias in dementia research.

PubMed

Weuve, Jennifer; Proust-Lima, Cécile; Power, Melinda C; Gross, Alden L; Hofer, Scott M; Thiébaut, Rodolphe; Chêne, Geneviève; Glymour, M Maria; Dufouil, Carole

2015-09-01

Clinical and population research on dementia and related neurologic conditions, including Alzheimer's disease, faces several unique methodological challenges. Progress to identify preventive and therapeutic strategies rests on valid and rigorous analytic approaches, but the research literature reflects little consensus on "best practices." We present findings from a large scientific working group on research methods for clinical and population studies of dementia, which identified five categories of methodological challenges as follows: (1) attrition/sample selection, including selective survival; (2) measurement, including uncertainty in diagnostic criteria, measurement error in neuropsychological assessments, and practice or retest effects; (3) specification of longitudinal models when participants are followed for months, years, or even decades; (4) time-varying measurements; and (5) high-dimensional data. We explain why each challenge is important in dementia research and how it could compromise the translation of research findings into effective prevention or care strategies. We advance a checklist of potential sources of bias that should be routinely addressed when reporting dementia research. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Determination of iodopropynyl butylcarbamate in cosmetic formulations utilizing pulsed splitless injection, gas chromatography with electron capture detector.

PubMed

Palmer, Kevin B; LaFon, William; Burford, Mark D

2017-09-22

Current analytical methodology for iodopropynyl butylcarbamate (IPBC) analysis focuses on the use of liquid chromatography and mass spectrometer (LC-MS), but the high instrumentation and operator investment required has resulted in the need for a cost effective alternative methodology. Past publications investigating gas chromatography with electron capture detector (GC-ECD) for IPBC quantitation proved largely unsuccessful, likely due to the preservatives limited thermal stability. The use of pulsed injection techniques commonly used for trace analysis of thermally labile pharmaceutical compounds was successfully adapted for IPBC analysis and utilizes the selectivity of GC-ECD analysis. System optimization and sample preparation improvements resulted in substantial performance and reproducibility gains. Cosmetic formulations preserved with IPBC (50-100ppm) were solvated in toluene/isopropyl alcohol and quantified over the 0.3-1.3μg/ml calibration range. The methodology was robust (relative standard deviation 4%), accurate (98% recovery), and sensitive (limit of detection 0.25ng/ml) for use in routine testing of cosmetic formulation preservation. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of a molecularly imprinted polymer for determination of steroids in goat milk by matrix solid phase dispersion.

PubMed

Gañán, Judith; Morante-Zarcero, Sonia; Gallego-Picó, Alejandrina; Garcinuño, Rosa María; Fernández-Hernando, Pilar; Sierra, Isabel

2014-08-01

A molecularly imprinted polymer-matrix solid-phase dispersion methodology for simultaneous determination of five steroids in goat milk samples was proposed. Factors affecting the extraction recovery such as sample/dispersant ratio and washing and elution solvents were investigated. The molecularly imprinted polymer used as dispersant in the matrix solid-phase dispersion procedure showed high affinity to steroids, and the obtained extracts were sufficiently cleaned to be directly analyzed. Analytical separation was performed by micellar electrokinetic chromatography using a capillary electrophoresis system equipped with a diode array detector. A background electrolyte composed of borate buffer (25mM, pH 9.3), sodium dodecyl sulfate (10mM) and acetonitrile (20%) was used. The developed MIP-MSPD methodology was applied for direct determination of testosterone (T), estrone (E1), 17β-estradiol (17β-E2), 17α-ethinylestradiol (EE2) and progesterone (P) in different goat milk samples. Mean recoveries obtained ranged from 81% to 110%, with relative standard deviations (RSD)≤12%. The molecularly imprinted polymer-matrix solid-phase dispersion method is fast, selective, cost-effective and environment-friendly compared with other pretreatment methods used for extraction of steroids in milk. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantitative 1H NMR: Development and Potential of an Analytical Method – an Update

PubMed Central

Pauli, Guido F.; Gödecke, Tanja; Jaki, Birgit U.; Lankin, David C.

2012-01-01

Covering the literature from mid-2004 until the end of 2011, this review continues a previous literature overview on quantitative 1H NMR (qHNMR) methodology and its applications in the analysis of natural products (NPs). Among the foremost advantages of qHNMR is its accurate function with external calibration, the lack of any requirement for identical reference materials, a high precision and accuracy when properly validated, and an ability to quantitate multiple analytes simultaneously. As a result of the inclusion of over 170 new references, this updated review summarizes a wealth of detailed experiential evidence and newly developed methodology that supports qHNMR as a valuable and unbiased analytical tool for natural product and other areas of research. PMID:22482996

Study of disulfide reduction and alkyl chloroformate derivatization of plasma sulfur amino acids using gas chromatography-mass spectrometry.

PubMed

Svagera, Zdeněk; Hanzlíková, Dagmar; Simek, Petr; Hušek, Petr

2012-03-01

Four disulfide-reducing agents, dithiothreitol (DTT), 2,3-dimercaptopropanesulfonate (DMPS), and the newly tested 2-mercaptoethanesulfonate (MESNA) and Tris(hydroxypropyl)phosphine (THP), were investigated in detail for release of sulfur amino acids in human plasma. After protein precipitation with trichloroacetic acid (TCA), the plasma supernatant was treated with methyl, ethyl, or propyl chloroformate via the well-proven derivatization-extraction technique and the products were subjected to gas chromatographic-mass spectrometric (GC-MS) analysis. All the tested agents proved to be rapid and effective reducing agents for the assay of plasma thiols. When compared with DTT, the novel reducing agents DMPS, MESNA, and THP provided much cleaner extracts and improved analytical performance. Quantification of homocysteine, cysteine, and methionine was performed using their deuterated analogues, whereas other analytes were quantified by means of 4-chlorophenylalanine. Precise and reliable assay of all examined analytes was achieved, irrespective of the chloroformate reagent used. Average relative standard deviations at each analyte level were ≤6%, quantification limits were 0.1-0.2 μmol L(-1), recoveries were 94-121%, and linearity was over three orders of magnitude (r(2) equal to 0.997-0.998). Validation performed with the THP agent and propyl chloroformate derivatization demonstrated the robustness and reliability of this simple sample-preparation methodology.

Determination of Polymer Additives-Antioxidants, Ultraviolet Stabilizers, Plasticizers and Photoinitiators in Plastic Food Package by Accelerated Solvent Extraction Coupled with High-Performance Liquid Chromatography.

PubMed

Li, Bo; Wang, Zhi-Wei; Lin, Qin-Bao; Hu, Chang-Ying; Su, Qi-Zhi; Wu, Yu-Mei

2015-07-01

An analytical method for the quantitative determination of 4 antioxidants, 9 ultraviolet (UV) stabilizers, 12 phthalate plasticizers and 2 photoinitiators in plastic food package using accelerated solvent extraction (ASE) coupled with high-performance liquid chromatography-photodiode array detector (HPLC-PDA) has been developed. Parameters affecting the efficiency in the process such as extraction and chromatographic conditions were studied in order to determine operating conditions. The analytical method of ASE-HPLC showed good linearity with good correlation coefficients (R ≥ 0.9833). The limits of detection and quantification were between 0.03 and 0.30 µg mL(-1) and between 0.10 and 1.00 µg mL(-1) for 27 analytes. Average spiked recoveries for most analytes in samples were >70.4% at 10, 20 and 40 µg g(-1) spiked levels, except UV-9 and Irganox 1010 (58.6 and 64.0% spiked at 10 µg g(-1), respectively), the relative standard deviations were in the range from 0.4 to 15.4%. The methodology has been proposed for the analysis of 27 polymer additives in plastic food package. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Absorption into fluorescence. A method to sense biologically relevant gas molecules

NASA Astrophysics Data System (ADS)

Strianese, Maria; Varriale, Antonio; Staiano, Maria; Pellecchia, Claudio; D'Auria, Sabato

2011-01-01

In this work we present an innovative optical sensing methodology based on the use of biomolecules as molecular gating nano-systems. Here, as an example, we report on the detection ofanalytes related to climate change. In particular, we focused our attention on the detection ofnitric oxide (NO) and oxygen (O2). Our methodology builds on the possibility of modulating the excitation intensity of a fluorescent probe used as a transducer and a sensor molecule whose absorption is strongly affected by the binding of an analyte of interest used as a filter. The two simple conditions that have to be fulfilled for the method to work are: (a) the absorption spectrum of the sensor placed inside the cuvette, and acting as the recognition element for the analyte of interest, should strongly change upon the binding of the analyte and (b) the fluorescence dye transducer should exhibit an excitation band which overlaps with one or more absorption bands of the sensor. The absorption band of the sensor affected by the binding of the specific analyte should overlap with the excitation band of the transducer. The high sensitivity of fluorescence detection combined with the use of proteins as highly selective sensors makes this method a powerful basis for the development of a new generation of analytical assays. Proof-of-principle results showing that cytochrome c peroxidase (CcP) for NO detection and myoglobin (Mb) for O2 detection can be successfully used by exploiting our new methodology are reported. The proposed technology can be easily expanded to the determination of different target analytes.

A Six Sigma Trial For Reduction of Error Rates in Pathology Laboratory.

PubMed

Tosuner, Zeynep; Gücin, Zühal; Kiran, Tuğçe; Büyükpinarbaşili, Nur; Turna, Seval; Taşkiran, Olcay; Arici, Dilek Sema

2016-01-01

A major target of quality assurance is the minimization of error rates in order to enhance patient safety. Six Sigma is a method targeting zero error (3.4 errors per million events) used in industry. The five main principles of Six Sigma are defining, measuring, analysis, improvement and control. Using this methodology, the causes of errors can be examined and process improvement strategies can be identified. The aim of our study was to evaluate the utility of Six Sigma methodology in error reduction in our pathology laboratory. The errors encountered between April 2014 and April 2015 were recorded by the pathology personnel. Error follow-up forms were examined by the quality control supervisor, administrative supervisor and the head of the department. Using Six Sigma methodology, the rate of errors was measured monthly and the distribution of errors at the preanalytic, analytic and postanalytical phases was analysed. Improvement strategies were reclaimed in the monthly intradepartmental meetings and the control of the units with high error rates was provided. Fifty-six (52.4%) of 107 recorded errors in total were at the pre-analytic phase. Forty-five errors (42%) were recorded as analytical and 6 errors (5.6%) as post-analytical. Two of the 45 errors were major irrevocable errors. The error rate was 6.8 per million in the first half of the year and 1.3 per million in the second half, decreasing by 79.77%. The Six Sigma trial in our pathology laboratory provided the reduction of the error rates mainly in the pre-analytic and analytic phases.

Sample preparation prior to the LC-MS-based metabolomics/metabonomics of blood-derived samples.

PubMed

Gika, Helen; Theodoridis, Georgios

2011-07-01

Blood represents a very important biological fluid and has been the target of continuous and extensive research for diagnostic, or health and drug monitoring reasons. Recently, metabonomics/metabolomics have emerged as a new and promising 'omics' platform that shows potential in biomarker discovery, especially in areas such as disease diagnosis, assessment of drug efficacy or toxicity. Blood is collected in various establishments in conditions that are not standardized. Next, the samples are prepared and analyzed using different methodologies or tools. When targeted analysis of key molecules (e.g., a drug or its metabolite[s]) is the aim, enforcement of certain measures or additional analyses may correct and harmonize these discrepancies. In omics fields such as those performed by holistic analytical approaches, no such rules or tools are available. As a result, comparison or correlation of results or data fusion becomes impractical. However, it becomes evident that such obstacles should be overcome in the near future to allow for large-scale studies that involve the assaying of samples from hundreds of individuals. In this case the effect of sample handling and preparation becomes very serious, in order to avoid wasting months of work from experts and expensive instrument time. The present review aims to cover the different methodologies applied to the pretreatment of blood prior to LC-MS metabolomic/metabonomic studies. The article tries to critically compare the methods and highlight issues that need to be addressed.

PTR-ToF-MS Coupled with an Automated Sampling System and Tailored Data Analysis for Food Studies: Bioprocess Monitoring, Screening and Nose-space Analysis.

PubMed

Capozzi, Vittorio; Yener, Sine; Khomenko, Iuliia; Farneti, Brian; Cappellin, Luca; Gasperi, Flavia; Scampicchio, Matteo; Biasioli, Franco

2017-05-11

Proton Transfer Reaction (PTR), combined with a Time-of-Flight (ToF) Mass Spectrometer (MS) is an analytical approach based on chemical ionization that belongs to the Direct-Injection Mass Spectrometric (DIMS) technologies. These techniques allow the rapid determination of volatile organic compounds (VOCs), assuring high sensitivity and accuracy. In general, PTR-MS requires neither sample preparation nor sample destruction, allowing real time and non-invasive analysis of samples. PTR-MS are exploited in many fields, from environmental and atmospheric chemistry to medical and biological sciences. More recently, we developed a methodology based on coupling PTR-ToF-MS with an automated sampler and tailored data analysis tools, to increase the degree of automation and, consequently, to enhance the potential of the technique. This approach allowed us to monitor bioprocesses (e.g. enzymatic oxidation, alcoholic fermentation), to screen large sample sets (e.g. different origins, entire germoplasms) and to analyze several experimental modes (e.g. different concentrations of a given ingredient, different intensities of a specific technological parameter) in terms of VOC content. Here, we report the experimental protocols exemplifying different possible applications of our methodology: i.e. the detection of VOCs released during lactic acid fermentation of yogurt (on-line bioprocess monitoring), the monitoring of VOCs associated with different apple cultivars (large-scale screening), and the in vivo study of retronasal VOC release during coffee drinking (nosespace analysis).

Radiometry in medicine and biology

NASA Astrophysics Data System (ADS)

Nahm, Kie-Bong; Choi, Eui Y.

2012-10-01

Diagnostics in medicine plays a critical role in helping medical professionals deliver proper diagnostic decisions. Most samples in this trade are of the human origin and a great portion of methodologies practiced in biology labs is shared in clinical diagnostic laboratories as well. Most clinical tests are quantitative in nature and recent increase in interests in preventive medicine requires the determination of minimal concentration of target analyte: they exist in small quantities at the early stage of various diseases. Radiometry or the use of optical radiation is the most trusted and reliable means of converting biologic concentrations into quantitative physical quantities. Since optical energy is readily available in varying energies (or wavelengths), the appropriate combination of light and the sample absorption properties provides reliable information about the sample concentration through Beer-Lambert law to a decent precision. In this article, the commonly practiced techniques in clinical and biology labs are reviewed from the standpoint of radiometry.

A Science and Risk-Based Pragmatic Methodology for Blend and Content Uniformity Assessment.

PubMed

Sayeed-Desta, Naheed; Pazhayattil, Ajay Babu; Collins, Jordan; Doshi, Chetan

2018-04-01

This paper describes a pragmatic approach that can be applied in assessing powder blend and unit dosage uniformity of solid dose products at Process Design, Process Performance Qualification, and Continued/Ongoing Process Verification stages of the Process Validation lifecycle. The statistically based sampling, testing, and assessment plan was developed due to the withdrawal of the FDA draft guidance for industry "Powder Blends and Finished Dosage Units-Stratified In-Process Dosage Unit Sampling and Assessment." This paper compares the proposed Grouped Area Variance Estimate (GAVE) method with an alternate approach outlining the practicality and statistical rationalization using traditional sampling and analytical methods. The approach is designed to fit solid dose processes assuring high statistical confidence in both powder blend uniformity and dosage unit uniformity during all three stages of the lifecycle complying with ASTM standards as recommended by the US FDA.

High-throughput simultaneous analysis of RNA, protein, and lipid biomarkers in heterogeneous tissue samples.

PubMed

Reiser, Vladimír; Smith, Ryan C; Xue, Jiyan; Kurtz, Marc M; Liu, Rong; Legrand, Cheryl; He, Xuanmin; Yu, Xiang; Wong, Peggy; Hinchcliffe, John S; Tanen, Michael R; Lazar, Gloria; Zieba, Renata; Ichetovkin, Marina; Chen, Zhu; O'Neill, Edward A; Tanaka, Wesley K; Marton, Matthew J; Liao, Jason; Morris, Mark; Hailman, Eric; Tokiwa, George Y; Plump, Andrew S

2011-11-01

With expanding biomarker discovery efforts and increasing costs of drug development, it is critical to maximize the value of mass-limited clinical samples. The main limitation of available methods is the inability to isolate and analyze, from a single sample, molecules requiring incompatible extraction methods. Thus, we developed a novel semiautomated method for tissue processing and tissue milling and division (TMAD). We used a SilverHawk atherectomy catheter to collect atherosclerotic plaques from patients requiring peripheral atherectomy. Tissue preservation by flash freezing was compared with immersion in RNAlater®, and tissue grinding by traditional mortar and pestle was compared with TMAD. Comparators were protein, RNA, and lipid yield and quality. Reproducibility of analyte yield from aliquots of the same tissue sample processed by TMAD was also measured. The quantity and quality of biomarkers extracted from tissue prepared by TMAD was at least as good as that extracted from tissue stored and prepared by traditional means. TMAD enabled parallel analysis of gene expression (quantitative reverse-transcription PCR, microarray), protein composition (ELISA), and lipid content (biochemical assay) from as little as 20 mg of tissue. The mean correlation was r = 0.97 in molecular composition (RNA, protein, or lipid) between aliquots of individual samples generated by TMAD. We also demonstrated that it is feasible to use TMAD in a large-scale clinical study setting. The TMAD methodology described here enables semiautomated, high-throughput sampling of small amounts of heterogeneous tissue specimens by multiple analytical techniques with generally improved quality of recovered biomolecules.

Evolved Gas Analysis and X-Ray Diffraction of Carbonate Samples from the 2009 Arctic Mars Analog Svalbard Expedition: Implications for Mineralogical Inferences from the Mars Science Laboratory

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Mahaffy, P. R.; Blake, D. F.; Ming, D. W.; Franz, H. B.; Eigenbrode, J. L.; Steele, A.

2010-01-01

The 2009 Arctic Mars Analog Svalbard Expedition (AMASE) investigated several geologic settings using methodologies and techniques being developed or considered for future Mars missions, such as the Mars Science Laboratory (MSL), ExoMars, and Mars Sample Return (MSR). AMASE-related research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions. The Sample Analysis at Mars (SAM) instrument suite, which will be part of the Analytical Laboratory on MSL, consists of a quadrupole mass spectrometer (QMS), a gas chromatograph (GC), and a tunable laser spectrometer (TLS). An Evolved Gas Analysis Mass Spectrometer (EGA-MS) was used during AMASE to represent part of the capabilities of SAM. The other instrument included in the MSL Analytical Laboratory is CheMin, which uses X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) to perform quantitative mineralogical characterization of samples. Field-portable versions of CheMin were used during the AMASE 2009. Here, we discuss the preliminary interpretation of EGA and XRD analyses of selected AMASE carbonate samples and implications for mineralogical interpretations from MSL. Though CheMin will be the primary mineralogical tool on MSL, SAM EGA could be used to support XRD identifications or indicate the presence of volatile-bearing minerals which may be near or below XRD detection limits. Data collected with instruments in the field and in comparable laboratory setups (e.g., the SAM breadboard) will be discussed.

Microextraction by Packed Sorbent (MEPS) and Solid-Phase Microextraction (SPME) as Sample Preparation Procedures for the Metabolomic Profiling of Urine

PubMed Central

Silva, Catarina; Cavaco, Carina; Perestrelo, Rosa; Pereira, Jorge; Câmara, José S.

2014-01-01

For a long time, sample preparation was unrecognized as a critical issue in the analytical methodology, thus limiting the performance that could be achieved. However, the improvement of microextraction techniques, particularly microextraction by packed sorbent (MEPS) and solid-phase microextraction (SPME), completely modified this scenario by introducing unprecedented control over this process. Urine is a biological fluid that is very interesting for metabolomics studies, allowing human health and disease characterization in a minimally invasive form. In this manuscript, we will critically review the most relevant and promising works in this field, highlighting how the metabolomic profiling of urine can be an extremely valuable tool for the early diagnosis of highly prevalent diseases, such as cardiovascular, oncologic and neurodegenerative ones. PMID:24958388

FTIR characterization of Mexican honey and its adulteration with sugar syrups by using chemometric methods

NASA Astrophysics Data System (ADS)

Rios-Corripio, M. A.; Rios-Leal, E.; Rojas-López, M.; Delgado-Macuil, R.

2011-01-01

A chemometric analysis of adulteration of Mexican honey by sugar syrups such as corn syrup and cane sugar syrup was realized. Fourier transform infrared spectroscopy (FTIR) was used to measure the absorption of a group of bee honey samples from central region of Mexico. Principal component analysis (PCA) was used to process FTIR spectra to determine the adulteration of bee honey. In addition to that, the content of individual sugars from honey samples: glucose, fructose, sucrose and monosaccharides was determined by using PLS-FTIR analysis validated by HPLC measurements. This analytical methodology which is based in infrared spectroscopy and chemometry can be an alternative technique to characterize and also to determine the purity and authenticity of nutritional products as bee honey and other natural products.

Determination of steroid sex hormones in water and urine matrices by stir bar sorptive extraction and liquid chromatography with diode array detection.

PubMed

Almeida, C; Nogueira, J M F

2006-06-16

In this study, stir bar sorptive extraction and liquid desorption followed by high performance liquid chromatography with diode array detection (SBSE-LD-HPLC/DAD) were combined for the simultaneous determination of nine steroid sex hormones (estrone, 17alpha-estradiol, 17beta-estradiol, 17alpha-ethynylestradiol, diethylstilbestrol, mestranol, progesterone, 19-norethisterone and norgestrel) in water and urine matrices. During the method development, it has been demonstrated that equilibrium time, ionic strength and back extraction solvents are the most important parameters to control, for determining the nine-hormones in water matrices, in which stir bars coated with 126 microl of polydimethylsiloxane were used. Assays performed on 30 ml water samples spiked at 10 microg/l levels under optimised experimental conditions, yielded recoveries ranging from 11.1+/-4.9% (17beta-estradiol) to 100.2+/-10.4% (mestranol), showed that the methodology is well described by the octanol-water partition coefficients (K(PDMS/W) approximately K(O/W)) for the latter, while pronounced deviations to the theoretical efficiency (K(PDMS/W) not equal K(O/W)) were observed for the remaining hormones. From calibration studies, a good analytical performance for all hormones was attained, including a suitable precision (2.1-17.1%), low limits of detection (0.3-1.0 microg/l) and an excellent linear dynamic range (1.25-50.0 microg/l). Assays on environmental water and urine matrices showed recovery yields in worthy good agreement with the spiking level (10 microg/l), and suitability for profiling low microg/l levels of natural hormones in urine samples taken from pregnant women. The present methodology is easy, reliable and sensitive at the trace level, only requiring a low sample volume, showing to be a good analytical alternative to routine quality control for environmental and biomedical laboratories.

High-Throughput Microbore UPLC-MS Metabolic Phenotyping of Urine for Large-Scale Epidemiology Studies.

PubMed

Gray, Nicola; Lewis, Matthew R; Plumb, Robert S; Wilson, Ian D; Nicholson, Jeremy K

2015-06-05

A new generation of metabolic phenotyping centers are being created to meet the increasing demands of personalized healthcare, and this has resulted in a major requirement for economical, high-throughput metabonomic analysis by liquid chromatography-mass spectrometry (LC-MS). Meeting these new demands represents an emerging bioanalytical problem that must be solved if metabolic phenotyping is to be successfully applied to large clinical and epidemiological sample sets. Ultraperformance (UP)LC-MS-based metabolic phenotyping, based on 2.1 mm i.d. LC columns, enables comprehensive metabolic phenotyping but, when employed for the analysis of thousands of samples, results in high solvent usage. The use of UPLC-MS employing 1 mm i.d. columns for metabolic phenotyping rather than the conventional 2.1 mm i.d. methodology shows that the resulting optimized microbore method provided equivalent or superior performance in terms of peak capacity, sensitivity, and robustness. On average, we also observed, when using the microbore scale separation, an increase in response of 2-3 fold over that obtained with the standard 2.1 mm scale method. When applied to the analysis of human urine, the 1 mm scale method showed no decline in performance over the course of 1000 analyses, illustrating that microbore UPLC-MS represents a viable alternative to conventional 2.1 mm i.d. formats for routine large-scale metabolic profiling studies while also resulting in a 75% reduction in solvent usage. The modest increase in sensitivity provided by this methodology also offers the potential to either reduce sample consumption or increase the number of metabolite features detected with confidence due to the increased signal-to-noise ratios obtained. Implementation of this miniaturized UPLC-MS method of metabolic phenotyping results in clear analytical, economic, and environmental benefits for large-scale metabolic profiling studies with similar or improved analytical performance compared to conventional UPLC-MS.

Design, Implementation, and Operational Methodologies for Sub-arcsecond Attitude Determination, Control, and Stabilization of the Super-pressure Balloon-Borne Imaging Telescope (SuperBIT)

NASA Astrophysics Data System (ADS)

Javier Romualdez, Luis

Scientific balloon-borne instrumentation offers an attractive, competitive, and effective alternative to space-borne missions when considering the overall scope, cost, and development timescale required to design and launch scientific instruments. In particular, the balloon-borne environment provides a near-space regime that is suitable for a number of modern astronomical and cosmological experiments, where the atmospheric interference suffered by ground-based instrumentation is negligible at stratospheric altitudes. This work is centered around the analytical strategies and implementation considerations for the attitude determination and control of SuperBIT, a scientific balloon-borne payload capable of meeting the strict sub-arcsecond pointing and image stability requirements demanded by modern cosmological experiments. Broadly speaking, the designed stability specifications of SuperBIT coupled with its observational efficiency, image quality, and accessibility rivals state-of-the-art astronomical observatories such as the Hubble Space Telescope. To this end, this work presents an end-to-end design methodology for precision pointing balloon-borne payloads such as SuperBIT within an analytical yet implementationally grounded context. Simulation models of SuperBIT are analytically derived to aid in pre-assembly trade-off and case studies that are pertinent to the dynamic balloon-borne environment. From these results, state estimation techniques and control methodologies are extensively developed, leveraging the analytical framework of simulation models and design studies. This pre-assembly design phase is physically validated during assembly, integration, and testing through implementation in real-time hardware and software, which bridges the gap between analytical results and practical application. SuperBIT attitude determination and control is demonstrated throughout two engineering test flights that verify pointing and image stability requirements in flight, where the post-flight results close the overall design loop by suggesting practical improvements to pre-design methodologies. Overall, the analytical and practical results presented in this work, though centered around the SuperBIT project, provide generically useful and implementationally viable methodologies for high precision balloon-borne instrumentation, all of which are validated, justified, and improved both theoretically and practically. As such, the continuing development of SuperBIT, built from the work presented in this thesis, strives to further the potential for scientific balloon-borne astronomy in the near future.

Understanding palliative care on the heart failure care team: an innovative research methodology.

PubMed

Lingard, Lorelei A; McDougall, Allan; Schulz, Valerie; Shadd, Joshua; Marshall, Denise; Strachan, Patricia H; Tait, Glendon R; Arnold, J Malcolm; Kimel, Gil

2013-05-01

There is a growing call to integrate palliative care for patients with advanced heart failure (HF). However, the knowledge to inform integration efforts comes largely from interview and survey research with individual patients and providers. This work has been critically important in raising awareness of the need for integration, but it is insufficient to inform solutions that must be enacted not by isolated individuals but by complex care teams. Research methods are urgently required to support systematic exploration of the experiences of patients with HF, family caregivers, and health care providers as they interact as a care team. To design a research methodology that can support systematic exploration of the experiences of patients with HF, caregivers, and health care providers as they interact as a care team. This article describes in detail a methodology that we have piloted and are currently using in a multisite study of HF care teams. We describe three aspects of the methodology: the theoretical framework, an innovative sampling strategy, and an iterative system of data collection and analysis that incorporates four data sources and four analytical steps. We anticipate that this innovative methodology will support groundbreaking research in both HF care and other team settings in which palliative integration efforts are emerging for patients with advanced nonmalignant disease. Copyright © 2013 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

Critical aspects of data analysis for quantification in laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Motto-Ros, V.; Syvilay, D.; Bassel, L.; Negre, E.; Trichard, F.; Pelascini, F.; El Haddad, J.; Harhira, A.; Moncayo, S.; Picard, J.; Devismes, D.; Bousquet, B.

2018-02-01

In this study, a collaborative contest focused on LIBS data processing has been conducted in an original way since the participants did not share the same samples to be analyzed on their own LIBS experiments but a set of LIBS spectra obtained from one single experiment. Each participant was asked to provide the predicted concentrations of several elements for two glass samples. The analytical contest revealed a wide diversity of results among participants, even when the same spectral lines were considered for the analysis. Then, a parametric study was conducted to investigate the influence of each step during the data processing. This study was based on several analytical figures of merit such as the determination coefficient, uncertainty, limit of quantification and prediction ability (i.e., trueness). Then, it was possible to interpret the results provided by the participants, emphasizing the fact that the type of data extraction, baseline modeling as well as the calibration model play key roles in the quantification performance of the technique. This work provides a set of recommendations based on a systematic evaluation of the quantification procedure with the aim of optimizing the methodological steps toward the standardization of LIBS.

Analytical strategies for organic food packaging contaminants.

PubMed

Sanchis, Yovana; Yusà, Vicent; Coscollà, Clara

2017-03-24

In this review, we present current approaches in the analysis of food-packaging contaminants. Gas and liquid chromatography coupled to mass spectrometry detection have been widely used in the analysis of some relevant families of these compounds such as primary aromatic amines, bisphenol A, bisphenol A diglycidyl ether and related compounds, UV-ink photoinitiators, perfluorinated compounds, phthalates and non-intentionally added substances. Main applications for sample treatment and different types of food-contact material migration studies have been also discussed. Pressurized Liquid Extraction, Solid-Phase Microextraction, Focused Ultrasound Solid-Liquid Extraction and Quechers have been mainly used in the extraction of food contact material (FCM) contaminants, due to the trend of minimising solvent consumption, automatization of sample preparation and integration of extraction and clean-up steps. Recent advances in analytical methodologies have allowed unequivocal identification and confirmation of these contaminants using Liquid Chromatography coupled to High Resolution Mass Spectrometry (LC-HRMS) through mass accuracy and isotopic pattern applying. LC-HRMS has been used in the target analysis of primary aromatic amines in different plastic materials, but few studies have been carried out applying this technique in post-target and non-target analysis of FCM contaminants. Copyright © 2017 Elsevier B.V. All rights reserved.

Incorporating Information Literacy Skills into Analytical Chemistry: An Evolutionary Step

ERIC Educational Resources Information Center

Walczak, Mary M.; Jackson, Paul T.

2007-01-01

The American Chemical Society (ACS) has recently decided to incorporate various information literacy skills for teaching analytical chemistry to the students. The methodology has been found to be extremely effective, as it provides better understanding to the students.

Critical review of the analysis of brominated flame retardants and their environmental levels in Africa.

PubMed

Brits, Martin; de Vos, Jayne; Weiss, Jana M; Rohwer, Egmont R; de Boer, Jacob

2016-12-01

World-wide, the prevalence of brominated flame retardants (BFRs) is well documented for routine analysis of environmental and biological matrices. There is, however, limited information on these compounds in the African environment and insufficient information on the analytical approaches used to obtain data. This paper presents a review on BFR levels in the African environment and the various analytical methodologies specifically applied in Africa for polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls and alternative-BFRs. The analyses include liquid sample preparation using liquid-liquid and solid phase extraction and solid sample preparation involving Soxhlet extraction, with ultrasound-assisted extraction increasingly being applied. Instrumental detection techniques were limited to gas chromatography coupled with electron capture detector and electron impact ionisation with single quadrupole mass spectrometers. Information on congener profile prevalence in indoor dust, soil, aquatic environment (water, sediment, and aquatic organisms), eggs, wastewater treatment plant compartments, landfills (leachate and sediment) and breast milk are presented. Although PBDEs were inconsistently detected, contamination was reported for all investigated matrices in the African environment. The manifestation in remote regions indicates the ubiquitous prevalence and long-range transport of these compounds. Levels in sediment, and breast milk from some African countries were higher than reported for Asia and Europe. Due to limited data or non-detection of alternative-BFRs, it is unclear whether banned formulations were replaced in Africa. Most of the data reported for BFR levels in Africa were obtained in non-African laboratories or in South Africa and formed the basis for our discussion of reported contamination levels and related methodologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Green approach using monolithic column for simultaneous determination of coformulated drugs.

PubMed

Yehia, Ali M; Mohamed, Heba M

2016-06-01

Green chemistry and sustainability is now entirely encompassed across the majority of pharmaceutical companies and research labs. Researchers' attention is careworn toward implementing the green analytical chemistry principles for more eco-friendly analytical methodologies. Solvents play a dominant role in determining the greenness of the analytical procedure. Using safer solvents, the greenness profile of the methodology could be increased remarkably. In this context, a green chromatographic method has been developed and validated for the simultaneous determination of phenylephrine, paracetamol, and guaifenesin in their ternary pharmaceutical mixture. The chromatographic separation was carried out using monolithic column and green solvents as mobile phase. The use of monolithic column allows efficient separation protocols at higher flow rates, which results in short time of analysis. Two-factor three-level experimental design was used to optimize the chromatographic conditions. The greenness profile of the proposed methodology was assessed using eco-scale as a green metrics and was found to be an excellent green method with regard to the usage and production of hazardous chemicals and solvents, energy consumption, and amount of produced waste. The proposed method improved the environmental impact without compromising the analytical performance criteria and could be used as a safer alternate for the routine analysis of the studied drugs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Assessment of analytical quality in Nordic clinical chemistry laboratories using data from contemporary national programs.

PubMed

Aronsson, T; Bjørnstad, P; Leskinen, E; Uldall, A; de Verdier, C H

1984-01-01

The aim of this investigation was primarily to assess analytical quality expressed as between-laboratory, within-laboratory, and total imprecision, not in order to detect laboratories with poor performance, but in the positive sense to provide data for improving critical steps in analytical methodology. The aim was also to establish the present state of the art in comparison with earlier investigations to see if improvement in analytical quality could be observed.

Prevalidation in pharmaceutical analysis. Part I. Fundamentals and critical discussion.

PubMed

Grdinić, Vladimir; Vuković, Jadranka

2004-05-28

A complete prevalidation, as a basic prevalidation strategy for quality control and standardization of analytical procedure was inaugurated. Fast and simple, the prevalidation methodology based on mathematical/statistical evaluation of a reduced number of experiments (N < or = 24) was elaborated and guidelines as well as algorithms were given in detail. This strategy has been produced for the pharmaceutical applications and dedicated to the preliminary evaluation of analytical methods where linear calibration model, which is very often occurred in practice, could be the most appropriate to fit experimental data. The requirements presented in this paper should therefore help the analyst to design and perform the minimum number of prevalidation experiments needed to obtain all the required information to evaluate and demonstrate the reliability of its analytical procedure. In complete prevalidation process, characterization of analytical groups, checking of two limiting groups, testing of data homogeneity, establishment of analytical functions, recognition of outliers, evaluation of limiting values and extraction of prevalidation parameters were included. Moreover, system of diagnosis for particular prevalidation step was suggested. As an illustrative example for demonstration of feasibility of prevalidation methodology, among great number of analytical procedures, Vis-spectrophotometric procedure for determination of tannins with Folin-Ciocalteu's phenol reagent was selected. Favourable metrological characteristics of this analytical procedure, as prevalidation figures of merit, recognized the metrological procedure as a valuable concept in preliminary evaluation of quality of analytical procedures.

Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

PubMed

van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

2015-12-18

The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of qualitative linguistic research--a pilot review integrating and generalizing findings on doctor-patient interaction.

PubMed

Nowak, Peter

2011-03-01

There is a broad range qualitative linguistic research (sequential analysis) on doctor-patient interaction that had only a marginal impact on clinical research and practice. At least in parts this is due to the lack of qualitative research synthesis in the field. Available research summaries are not systematic in their methodology. This paper proposes a synthesis methodology for qualitative, sequential analytic research on doctor-patient interaction. The presented methodology is not new but specifies standard methodology of qualitative research synthesis for sequential analytic research. This pilot review synthesizes twelve studies on German-speaking doctor-patient interactions, identifies 45 verbal actions of doctors and structures them in a systematics of eight interaction components. Three interaction components ("Listening", "Asking for information", and "Giving information") seem to be central and cover two thirds of the identified action types. This pilot review demonstrates that sequential analytic research can be synthesized in a consistent and meaningful way, thus providing a more comprehensive and unbiased integration of research. Future synthesis of qualitative research in the area of health communication research is very much needed. Qualitative research synthesis can support the development of quantitative research and of educational materials in medical training and patient training. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The Literature Review of Analytical Support to Defence Transformation: Lessons Learned from Turkish Air Force Transformation Activities

DTIC Science & Technology

2010-04-01

available [11]. Additionally, Table-3 is a guide for DMAIC methodology including 29 different methods [12]. RTO-MP-SAS-081 6 - 4 NATO UNCLASSIFIED NATO...Table 3: DMAIC Methodology (5-Phase Methodology). Define Measure Analyze Improve Control Project Charter Prioritization Matrix 5 Whys Analysis...Methodology Scope [13] DMAIC PDCA Develop performance priorities This is a preliminary stage that precedes specific improvement projects, and the aim

Model and Analytic Processes for Export License Assessments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Sandra E.; Whitney, Paul D.; Weimar, Mark R.

2011-09-29

This paper represents the Department of Energy Office of Nonproliferation Research and Development (NA-22) Simulations, Algorithms and Modeling (SAM) Program's first effort to identify and frame analytical methods and tools to aid export control professionals in effectively predicting proliferation intent; a complex, multi-step and multi-agency process. The report focuses on analytical modeling methodologies that alone, or combined, may improve the proliferation export control license approval process. It is a follow-up to an earlier paper describing information sources and environments related to international nuclear technology transfer. This report describes the decision criteria used to evaluate modeling techniques and tools to determinemore » which approaches will be investigated during the final 2 years of the project. The report also details the motivation for why new modeling techniques and tools are needed. The analytical modeling methodologies will enable analysts to evaluate the information environment for relevance to detecting proliferation intent, with specific focus on assessing risks associated with transferring dual-use technologies. Dual-use technologies can be used in both weapons and commercial enterprises. A decision-framework was developed to evaluate which of the different analytical modeling methodologies would be most appropriate conditional on the uniqueness of the approach, data availability, laboratory capabilities, relevance to NA-22 and Office of Arms Control and Nonproliferation (NA-24) research needs and the impact if successful. Modeling methodologies were divided into whether they could help micro-level assessments (e.g., help improve individual license assessments) or macro-level assessment. Macro-level assessment focuses on suppliers, technology, consumers, economies, and proliferation context. Macro-level assessment technologies scored higher in the area of uniqueness because less work has been done at the macro level. An approach to developing testable hypotheses for the macro-level assessment methodologies is provided. The outcome of this works suggests that we should develop a Bayes Net for micro-level analysis and continue to focus on Bayes Net, System Dynamics and Economic Input/Output models for assessing macro-level problems. Simultaneously, we need to develop metrics for assessing intent in export control, including the risks and consequences associated with all aspects of export control.« less

Method for Operating a Sensor to Differentiate Between Analytes in a Sample

DOEpatents

Kunt, Tekin; Cavicchi, Richard E; Semancik, Stephen; McAvoy, Thomas J

1998-07-28

Disclosed is a method for operating a sensor to differentiate between first and second analytes in a sample. The method comprises the steps of determining a input profile for the sensor which will enhance the difference in the output profiles of the sensor as between the first analyte and the second analyte; determining a first analyte output profile as observed when the input profile is applied to the sensor; determining a second analyte output profile as observed when the temperature profile is applied to the sensor; introducing the sensor to the sample while applying the temperature profile to the sensor, thereby obtaining a sample output profile; and evaluating the sample output profile as against the first and second analyte output profiles to thereby determine which of the analytes is present in the sample.

Analytical Comparison of In Vitro-Spiked Human Serum and Plasma for PCR-Based Detection of Aspergillus fumigatus DNA: a Study by the European Aspergillus PCR Initiative

PubMed Central

Mengoli, Carlo; Springer, Jan; Bretagne, Stéphane; Cuenca-Estrella, Manuel; Klingspor, Lena; Lagrou, Katrien; Melchers, Willem J. G.; Morton, C. Oliver; Barnes, Rosemary A.; Donnelly, J. Peter; White, P. Lewis

2015-01-01

The use of serum or plasma for Aspergillus PCR testing facilitates automated and standardized technology. Recommendations for serum testing are available, and while serum and plasma are regularly considered interchangeable for use in fungal diagnostics, differences in galactomannan enzyme immunoassay (GM-EIA) performance have been reported and are attributed to clot formation. Therefore, it is important to assess plasma PCR testing to determine if previous recommendations for serum are applicable and also to compare analytical performance with that of serum PCR. Molecular methods testing serum and plasma were compared through multicenter distribution of quality control panels, with additional studies to investigate the effect of clot formation and blood fractionation on DNA availability. Analytical sensitivity and time to positivity (TTP) were compared, and a regression analysis was performed to identify variables that enhanced plasma PCR performance. When testing plasma, sample volume, preextraction-to-postextraction volume ratio, PCR volume, duplicate testing, and the use of an internal control for PCR were positively associated with performance. When whole-blood samples were spiked and then fractionated, the analytical sensitivity and TTP were superior when testing plasma. Centrifugation had no effect on DNA availability, whereas the presence of clot material significantly lowered the concentration (P = 0.028). Technically, there are no major differences in the molecular processing of serum and plasma, but the formation of clot material potentially reduces available DNA in serum. During disease, Aspergillus DNA burdens in blood are often at the limits of PCR performance. Using plasma might improve performance while maintaining the methodological simplicity of serum testing. PMID:26085614

Methodological requirements for valid tissue-based biomarker studies that can be used in clinical practice.

PubMed

True, Lawrence D

2014-03-01

Paralleling the growth of ever more cost efficient methods to sequence the whole genome in minute fragments of tissue has been the identification of increasingly numerous molecular abnormalities in cancers--mutations, amplifications, insertions and deletions of genes, and patterns of differential gene expression, i.e., overexpression of growth factors and underexpression of tumor suppressor genes. These abnormalities can be translated into assays to be used in clinical decision making. In general terms, the result of such an assay is subject to a large number of variables regarding the characteristics of the available sample, particularities of the used assay, and the interpretation of the results. This review discusses the effects of these variables on assays of tissue-based biomarkers, classified by macromolecule--DNA, RNA (including micro RNA, messenger RNA, long noncoding RNA, protein, and phosphoprotein). Since the majority of clinically applicable biomarkers are immunohistochemically detectable proteins this review focuses on protein biomarkers. However, the principles outlined are mostly applicable to any other analyte. A variety of preanalytical variables impacts on the results obtained, including analyte stability (which is different for different analytes, i.e., DNA, RNA, or protein), period of warm and of cold ischemia, fixation time, tissue processing, sample storage time, and storage conditions. In addition, assay variables play an important role, including reagent specificity (notably but not uniquely an issue concerning antibodies used in immunohistochemistry), technical components of the assay, quantitation, and assay interpretation. Finally, appropriateness of an assay for clinical application is an important issue. Reference is made to publicly available guidelines to improve on biomarker development in general and requirements for clinical use in particular. Strategic goals are formulated in order to improve on the quality of biomarker reporting, including issues of analyte quality, experimental detail, assay efficiency and precision, and assay appropriateness.

Analytical Comparison of In Vitro-Spiked Human Serum and Plasma for PCR-Based Detection of Aspergillus fumigatus DNA: a Study by the European Aspergillus PCR Initiative.

PubMed

Loeffler, Juergen; Mengoli, Carlo; Springer, Jan; Bretagne, Stéphane; Cuenca-Estrella, Manuel; Klingspor, Lena; Lagrou, Katrien; Melchers, Willem J G; Morton, C Oliver; Barnes, Rosemary A; Donnelly, J Peter; White, P Lewis

2015-09-01

The use of serum or plasma for Aspergillus PCR testing facilitates automated and standardized technology. Recommendations for serum testing are available, and while serum and plasma are regularly considered interchangeable for use in fungal diagnostics, differences in galactomannan enzyme immunoassay (GM-EIA) performance have been reported and are attributed to clot formation. Therefore, it is important to assess plasma PCR testing to determine if previous recommendations for serum are applicable and also to compare analytical performance with that of serum PCR. Molecular methods testing serum and plasma were compared through multicenter distribution of quality control panels, with additional studies to investigate the effect of clot formation and blood fractionation on DNA availability. Analytical sensitivity and time to positivity (TTP) were compared, and a regression analysis was performed to identify variables that enhanced plasma PCR performance. When testing plasma, sample volume, preextraction-to-postextraction volume ratio, PCR volume, duplicate testing, and the use of an internal control for PCR were positively associated with performance. When whole-blood samples were spiked and then fractionated, the analytical sensitivity and TTP were superior when testing plasma. Centrifugation had no effect on DNA availability, whereas the presence of clot material significantly lowered the concentration (P = 0.028). Technically, there are no major differences in the molecular processing of serum and plasma, but the formation of clot material potentially reduces available DNA in serum. During disease, Aspergillus DNA burdens in blood are often at the limits of PCR performance. Using plasma might improve performance while maintaining the methodological simplicity of serum testing. Copyright © 2015 Loeffler et al.

Analysis of combined data from heterogeneous study designs: an applied example from the patient navigation research program.

PubMed

Roetzheim, Richard G; Freund, Karen M; Corle, Don K; Murray, David M; Snyder, Frederick R; Kronman, Andrea C; Jean-Pierre, Pascal; Raich, Peter C; Holden, Alan Ec; Darnell, Julie S; Warren-Mears, Victoria; Patierno, Steven

2012-04-01

The Patient Navigation Research Program (PNRP) is a cooperative effort of nine research projects, with similar clinical criteria but with different study designs. To evaluate projects such as PNRP, it is desirable to perform a pooled analysis to increase power relative to the individual projects. There is no agreed-upon prospective methodology, however, for analyzing combined data arising from different study designs. Expert opinions were thus solicited from the members of the PNRP Design and Analysis Committee. To review possible methodologies for analyzing combined data arising from heterogeneous study designs. The Design and Analysis Committee critically reviewed the pros and cons of five potential methods for analyzing combined PNRP project data. The conclusions were based on simple consensus. The five approaches reviewed included the following: (1) analyzing and reporting each project separately, (2) combining data from all projects and performing an individual-level analysis, (3) pooling data from projects having similar study designs, (4) analyzing pooled data using a prospective meta-analytic technique, and (5) analyzing pooled data utilizing a novel simulated group-randomized design. Methodologies varied in their ability to incorporate data from all PNRP projects, to appropriately account for differing study designs, and to accommodate differing project sample sizes. The conclusions reached were based on expert opinion and not derived from actual analyses performed. The ability to analyze pooled data arising from differing study designs may provide pertinent information to inform programmatic, budgetary, and policy perspectives. Multisite community-based research may not lend itself well to the more stringent explanatory and pragmatic standards of a randomized controlled trial design. Given our growing interest in community-based population research, the challenges inherent in the analysis of heterogeneous study design are likely to become more salient. Discussion of the analytic issues faced by the PNRP and the methodological approaches we considered may be of value to other prospective community-based research programs.

The application of headspace gas chromatography coupled to tandem quadrupole mass spectrometry for the analysis of furan in baby food samples.

PubMed

Pugajeva, Iveta; Rozentale, Irina; Viksna, Arturs; Bartkiene, Elena; Bartkevics, Vadims

2016-12-01

Selective methodology employing a tandem quadrupole mass spectrometer coupled to a gas chromatograph with headspace autosampler (HS-GC-MS/MS) was elaborated in this study. Application of the elaborated procedure resulted in a limit of detection of 0.021μgkg(-1) and a limit of quantification of 0.071μgkg(-1). The mean recoveries during in-house validation ranged from 89% to 109%, and coefficients of variation for repeatability ranged from 4% to 11%. The proposed analytical method was applied for monitoring the furan content of 30 commercial baby food samples available on the Latvian retail market. The level of furan found in these samples varied from 0.45 to 81.9μgkg(-1), indicating that infants whose sole diet comprises baby food sold in jars and cans are exposed constantly to furan. Samples containing vegetables and meat had higher levels of furan than those containing only fruits. Copyright © 2016 Elsevier Ltd. All rights reserved.

Passenger rail vehicle safety assessment methodology. Volume II, Detailed analyses and simulation results.

DOT National Transportation Integrated Search

2000-04-01

This report presents detailed analytic tools and results on dynamic response which are used to develop the safe dynamic performance limits of commuter passenger vehicles. The methodology consists of determining the critical parameters and characteris...

Xpey' Relational Environments: an analytic framework for conceptualizing Indigenous health equity.

PubMed

Kent, Alexandra; Loppie, Charlotte; Carriere, Jeannine; MacDonald, Marjorie; Pauly, Bernie

2017-12-01

Both health equity research and Indigenous health research are driven by the goal of promoting equitable health outcomes among marginalized and underserved populations. However, the two fields often operate independently, without collaboration. As a result, Indigenous populations are underrepresented in health equity research relative to the disproportionate burden of health inequities they experience. In this methodological article, we present Xpey' Relational Environments, an analytic framework that maps some of the barriers and facilitators to health equity for Indigenous peoples. Health equity research needs to include a focus on Indigenous populations and Indigenized methodologies, a shift that could fill gaps in knowledge with the potential to contribute to 'closing the gap' in Indigenous health. With this in mind, the Equity Lens in Public Health (ELPH) research program adopted the Xpey' Relational Environments framework to add a focus on Indigenous populations to our research on the prioritization and implementation of health equity. The analytic framework introduced an Indigenized health equity lens to our methodology, which facilitated the identification of social, structural and systemic determinants of Indigenous health. To test the framework, we conducted a pilot case study of one of British Columbia's regional health authorities, which included a review of core policies and plans as well as interviews and focus groups with frontline staff, managers and senior executives. ELPH's application of Xpey' Relational Environments serves as an example of the analytic framework's utility for exploring and conceptualizing Indigenous health equity in BC's public health system. Future applications of the framework should be embedded in Indigenous research methodologies.

Analytical technique characterizes all trace contaminants in water

NASA Technical Reports Server (NTRS)

Foster, J. N.; Lysyj, I.; Nelson, K. H.

1967-01-01

Properly programmed combination of advanced chemical and physical analytical techniques characterize critically all trace contaminants in both the potable and waste water from the Apollo Command Module. This methodology can also be applied to the investigation of the source of water pollution.

Distribution of Amino Acids in Lunar Regolith

NASA Technical Reports Server (NTRS)

Elsila, J. E.; Callahan, M. P.; Glavin, D. P.; Dworkin, J. P.; Noble, S. K.; Gibson, E. K., Jr.

2014-01-01

One of the most eagerly studied questions upon initial return of lunar samples was whether significant amounts of organic compounds, including amino acids, were present. Analyses during the 1970s produced only tentative and inconclusive identifications of indigenous amino acids. Those analyses were hampered by analytical difficulties including relative insensitivity to certain compounds, the inability to separate chiral enantiomers, and the lack of compound-specific isotopic measurements, which made it impossible to determine whether the detected amino acids were indigenous to the lunar samples or the results of contamination. Numerous advances have been made in instrumentation and methodology for amino acid characterization in extraterrestrial samples in the intervening years, yet the origin of amino acids in lunar regolith samples has been revisited only once for a single lunar sample, (3) and remains unclear. Here, we present initial data from the analyses of amino acid abundances in 12 lunar regolith samples. We discuss these abundances in the context of four potential amino acid sources: (1) terrestrial biological contamination; (2) contamination from lunar module (LM) exhaust; (3) derivation from solar windimplanted precursors; and (4) exogenous delivery from meteorites.

How Much Can We Learn from a Single Chromatographic Experiment? A Bayesian Perspective.

PubMed

Wiczling, Paweł; Kaliszan, Roman

2016-01-05

In this work, we proposed and investigated a Bayesian inference procedure to find the desired chromatographic conditions based on known analyte properties (lipophilicity, pKa, and polar surface area) using one preliminary experiment. A previously developed nonlinear mixed effect model was used to specify the prior information about a new analyte with known physicochemical properties. Further, the prior (no preliminary data) and posterior predictive distribution (prior + one experiment) were determined sequentially to search towards the desired separation. The following isocratic high-performance reversed-phase liquid chromatographic conditions were sought: (1) retention time of a single analyte within the range of 4-6 min and (2) baseline separation of two analytes with retention times within the range of 4-10 min. The empirical posterior Bayesian distribution of parameters was estimated using the "slice sampling" Markov Chain Monte Carlo (MCMC) algorithm implemented in Matlab. The simulations with artificial analytes and experimental data of ketoprofen and papaverine were used to test the proposed methodology. The simulation experiment showed that for a single and two randomly selected analytes, there is 97% and 74% probability of obtaining a successful chromatogram using none or one preliminary experiment. The desired separation for ketoprofen and papaverine was established based on a single experiment. It was confirmed that the search for a desired separation rarely requires a large number of chromatographic analyses at least for a simple optimization problem. The proposed Bayesian-based optimization scheme is a powerful method of finding a desired chromatographic separation based on a small number of preliminary experiments.

Quantifying construction and demolition waste: An analytical review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Zezhou; Yu, Ann T.W., E-mail: bsannyu@polyu.edu.hk; Shen, Liyin

2014-09-15

Highlights: • Prevailing C and D waste quantification methodologies are identified and compared. • One specific methodology cannot fulfill all waste quantification scenarios. • A relevance tree for appropriate quantification methodology selection is proposed. • More attentions should be paid to civil and infrastructural works. • Classified information is suggested for making an effective waste management plan. - Abstract: Quantifying construction and demolition (C and D) waste generation is regarded as a prerequisite for the implementation of successful waste management. In literature, various methods have been employed to quantify the C and D waste generation at both regional and projectmore » levels. However, an integrated review that systemically describes and analyses all the existing methods has yet to be conducted. To bridge this research gap, an analytical review is conducted. Fifty-seven papers are retrieved based on a set of rigorous procedures. The characteristics of the selected papers are classified according to the following criteria - waste generation activity, estimation level and quantification methodology. Six categories of existing C and D waste quantification methodologies are identified, including site visit method, waste generation rate method, lifetime analysis method, classification system accumulation method, variables modelling method and other particular methods. A critical comparison of the identified methods is given according to their characteristics and implementation constraints. Moreover, a decision tree is proposed for aiding the selection of the most appropriate quantification method in different scenarios. Based on the analytical review, limitations of previous studies and recommendations of potential future research directions are further suggested.« less

Differential global profiling as a new analytical strategy for revealing micropollutant treatment by-products: application to ethinylestradiol and chlorination water treatment.

PubMed

Gervais, Gaël; Bichon, Emmanuelle; Antignac, Jean-Philippe; Monteau, Fabrice; Leroy, Gaëla; Barritaud, Lauriane; Chachignon, Mathilde; Ingrand, Valérie; Roche, Pascal; Le Bizec, Bruno

2011-06-01

The detection and structural elucidation of micropollutants treatment by-products are major issues to estimate efficiencies of the processes employed for drinking water production versus endocrine disruptive compounds contamination. This issue was mainly investigated at the laboratory scale and in high concentration conditions. However, potential by-products generated after chlorination can be influenced by the dilution factor employed in real conditions. The present study proposes a new methodology borrowed to the metabolomic science, using liquid chromatography coupled to high-resolution mass spectrometry, in order to reveal potential chlorination by-products of ethinylestradiol in spiked real water samples at the part-per-billion level (5 μg L(-1)). Conventional targeted measurements first demonstrated that chlorination with sodium hypochlorite (0.8 mg L(-1)) led to removals of ethinylestradiol over 97%. Then, the developed differential global profiling approach permitted to reveal eight chlorination by-products of EE2, six of them being described for the first time. Among these eight halogenated compounds, five have been structurally identified, demonstrating the potential capabilities of this new methodology applied to environmental samples. Copyright © 2011 Elsevier Ltd. All rights reserved.

Monitoring the contents of six steroidal and phenolic endocrine disrupting chemicals in chicken, fish and aquaculture pond water samples using pre-column derivatization and dispersive liquid-liquid microextraction with the aid of experimental design methodology.

PubMed

Wu, Hongliang; Li, Guoliang; Liu, Shucheng; Hu, Na; Geng, Dandan; Chen, Guang; Sun, Zhiwei; Zhao, Xianen; Xia, Lian; You, Jinmao

2016-02-01

This research established a sensitive and efficient pre-column derivatization HPLC method based on dispersive liquid-liquid microextraction (DLLME) for the simultaneous determination of six steroidal and phenolic endocrine disrupting chemicals (EDCs). In this study, EDCs were firstly labeled by the derivatization reagent 2-(11H-benzo[a]carbazol-11-yl) ethyl carbonochloridate (BCEC-Cl) and then extracted by DLLME. The response surface methodology was employed to investigate the key parameters of pre-column derivatization and DLLME. Under the optimal conditions, a good linear relationship between the peak area and the concentration of analytes was observed with correlation coefficients of >0.9991. Limits of detection for all EDCs derivatives were achieved within the range of 0.02-0.07 μg L(-1). The proposed method has the advantages of simple operation, low consumption of organic solvent, saving time, low output limit and good selectivity. When applied to several food and water samples analysis, it demonstrated good applicability for the determination of EDCs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemical speciation of individual airborne particles by the combined use of quantitative energy-dispersive electron probe X-ray microanalysis and attenuated total reflection Fourier transform-infrared imaging techniques.

PubMed

Song, Young-Chul; Ryu, JiYeon; Malek, Md Abdul; Jung, Hae-Jin; Ro, Chul-Un

2010-10-01

In our previous work, it was demonstrated that the combined use of attenuated total reflectance (ATR) FT-IR imaging and quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), named low-Z particle EPMA, had the potential for characterization of individual aerosol particles. Additionally, the speciation of individual mineral particles was performed on a single particle level by the combined use of the two techniques, demonstrating that simultaneous use of the two single particle analytical techniques is powerful for the detailed characterization of externally heterogeneous mineral particle samples and has great potential for characterization of atmospheric mineral dust aerosols. These single particle analytical techniques provide complementary information on the physicochemical characteristics of the same individual particles, such as low-Z particle EPMA on morphology and elemental concentrations and the ATR-FT-IR imaging on molecular species, crystal structures, functional groups, and physical states. In this work, this analytical methodology was applied to characterize an atmospheric aerosol sample collected in Incheon, Korea. Overall, 118 individual particles were observed to be primarily NaNO(3)-containing, Ca- and/or Mg-containing, silicate, and carbonaceous particles, although internal mixing states of the individual particles proved complicated. This work demonstrates that more detailed physiochemical properties of individual airborne particles can be obtained using this approach than when either the low-Z particle EPMA or ATR-FT-IR imaging technique is used alone.

Evaluation of bioaccumulation kinetics of gold nanorods in vital mammalian organs by means of total reflection X-ray fluorescence spectrometry.

PubMed

Fernández-Ruiz, Ramón; Redrejo, María Jesús; Friedrich, Eberhardt Josué; Ramos, Milagros; Fernández, Tamara

2014-08-05

This work presents the first application of total-reflection X-ray fluorescence (TXRF) spectrometry, a new and powerful alternative analytical method, to evaluation of the bioaccumulation kinetics of gold nanorods (GNRs) in various tissues upon intravenous administration in mice. The analytical parameters for developed methodology by TXRF were evaluated by means of the parallel analysis of bovine liver certified reference material samples (BCR-185R) doped with 10 μg/g gold. The average values (n = 5) achieved for gold measurements in lyophilized tissue weight were as follows: recovery 99.7%, expanded uncertainty (k = 2) 7%, repeatability 1.7%, detection limit 112 ng/g, and quantification limit 370 ng/g. The GNR bioaccumulation kinetics was analyzed in several vital mammalian organs such as liver, spleen, brain, and lung at different times. Additionally, urine samples were analyzed to study the kinetics of elimination of the GNRs by this excretion route. The main achievement was clearly differentiating two kinds of behaviors. GNRs were quickly bioaccumulated by highly vascular filtration organs such as liver and spleen, while GNRs do not show a bioaccumulation rates in brain and lung for the period of time investigated. In parallel, urine also shows a lack of GNR accumulation. TXRF has proven to be a powerful, versatile, and precise analytical technique for the evaluation of GNRs content in biological systems and, in a more general way, for any kind of metallic nanoparticles.

Eco-friendly LC-MS/MS method for analysis of multi-class micropollutants in tap, fountain, and well water from northern Portugal.

PubMed

Barbosa, Marta O; Ribeiro, Ana R; Pereira, Manuel F R; Silva, Adrián M T

2016-11-01

Organic micropollutants present in drinking water (DW) may cause adverse effects for public health, and so reliable analytical methods are required to detect these pollutants at trace levels in DW. This work describes the first green analytical methodology for multi-class determination of 21 pollutants in DW: seven pesticides, an industrial compound, 12 pharmaceuticals, and a metabolite (some included in Directive 2013/39/EU or Decision 2015/495/EU). A solid-phase extraction procedure followed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (offline SPE-UHPLC-MS/MS) method was optimized using eco-friendly solvents, achieving detection limits below 0.20 ng L -1 . The validated analytical method was successfully applied to DW samples from different sources (tap, fountain, and well waters) from different locations in the north of Portugal, as well as before and after bench-scale UV and ozonation experiments in spiked tap water samples. Thirteen compounds were detected, many of them not regulated yet, in the following order of frequency: diclofenac > norfluoxetine > atrazine > simazine > warfarin > metoprolol > alachlor > chlorfenvinphos > trimethoprim > clarithromycin ≈ carbamazepine ≈ PFOS > citalopram. Hazard quotients were also estimated for the quantified substances and suggested no adverse effects to humans. Graphical Abstract Occurrence and removal of multi-class micropollutants in drinking water, analyzed by an eco-friendly LC-MS/MS method.

Comparison of two microextraction methods based on solidification of floating organic droplet for the determination of multiclass analytes in river water samples by liquid chromatography tandem mass spectrometry using Central Composite Design.

PubMed

Asati, Ankita; Satyanarayana, G N V; Patel, Devendra K

2017-09-01

Two low density organic solvents based liquid-liquid microextraction methods, namely Vortex assisted liquid-liquid microextraction based on solidification of floating organic droplet (VALLME-SFO) and Dispersive liquid-liquid microextraction based on solidification of floating organic droplet(DLLME-SFO) have been compared for the determination of multiclass analytes (pesticides, plasticizers, pharmaceuticals and personal care products) in river water samples by using liquid chromatography tandem mass spectrometry (LC-MS/MS). The effect of various experimental parameters on the efficiency of the two methods and their optimum values were studied with the aid of Central Composite Design (CCD) and Response Surface Methodology(RSM). Under optimal conditions, VALLME-SFO was validated in terms of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery for which the respective values were (0.011-0.219ngmL -1 ), (0.035-0.723ngmL -1 ), (0.050-0.500ngmL -1 ), (R 2 =0.992-0.999), (40-56), (80-106%). However, when the DLLME-SFO method was validated under optimal conditions, the range of values of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery were (0.025-0.377ngmL -1 ), (0.083-1.256ngmL -1 ), (0.100-1.000ngmL -1 ), (R 2 =0.990-0.999), (35-49), (69-98%) respectively. Interday and intraday precisions were calculated as percent relative standard deviation (%RSD) and the values were ≤15% for VALLME-SFO and DLLME-SFO methods. Both methods were successfully applied for determining multiclass analytes in river water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Ozone Modulation/Membrane Introduction Mass Spectrometry for Analysis of Hydrocarbon Pollutants in Air

NASA Astrophysics Data System (ADS)

Atkinson, D. B.

2001-12-01

Modulation of volatile hydrocarbons in two-component mixtures is demonstrated using an ozonolysis pretreatment with membrane introduction mass spectrometry (MIMS). The MIMS technique allows selective introduction of volatile and semivolatile analytes into a mass spectrometer via processes known collectively as pervaporation [Kotiaho and Cooks, 1992]. A semipermeable polymer membrane acts as an interface between the sample (vapor or solution) and the vacuum of the mass spectrometer. This technique has been demonstrated to allow for sensitive analysis of hydrocarbons and other non-polar volatile organic compounds (VOC`s) in air samples[Cisper et al., 1995] . The methodology has the advantages of no sample pretreatment and short analysis time, which are promising for online monitoring applications but the chief disadvantage of lack of a separation step for the different analytes in a mixture. Several approaches have been investigated to overcome this problem including use of selective chemical ionization [Bier and Cooks, 1987] and multivariate calibration techniques[Ketola et al., 1999] . A new approach is reported for the quantitative measurement of VOCs in complex matrices. The method seeks to reduce the complexity of mass spectra observed in hydrocarbon mixture analysis by selective pretreatment of the analyte mixture. In the current investigation, the rapid reaction of ozone with alkenes is used, producing oxygenated compounds which are suppressed by the MIMS system. This has the effect of removing signals due to unsaturated analytes from the compound mass spectra, and comparison of the spectra before and after the ozone treatment reveals the nature of the parent compounds. In preliminary investigations, ozone reacted completely with cyclohexene from a mixture of cylohexene and cyclohexane, and with β -pinene from a mixture of toluene and β -pinene, suppressing the ion signals from the olefins. A slight attenuation of the cyclohexane and toluene in those mixtures was also observed. Despite this problem, the hydrocarbon signal response can be calibrated and the method can be used for quantitative analysis of volatile hydrocarbon compounds in air samples. This methodology should augment the efficiency of the MIMS approach in online and onsite monitoring of VOC emissions. Bier, M.R., and R.G. Cooks, Membrane Interface for Selective Introduction of Volatile Compounds Directly into The Ionization Chamber of a Mass Spectrometer, Anal. Chem., 59 (4), 597, 1987. Cisper, M.E., C.G. Gill, L.E. Townsend, and P.H. Hemberger, On-Line Detection of Volatile Organic Compounds in Air at Parts-per-Trillion Levels by Membrane Introduction Mass Spectrometry, Anal. Chem., 67 (8), 1413-1417, 1995. Ketola, R.A., M. Ojala, and J. Heikkonen, A Non-linear Asymmetric Error Function-based Least Mean Square Approach for the Analysis of Multicomponent Mass Spectra Measured by Membrane Inlet Mass Spectrometry, Rapid Commun. Mass Spectrom., 13 (8), 654, 1999. Kotiaho, T., and R.G. Cooks, Membrane Introduction Mass Spectrometry in Environmental Analysis, in: J.J. Breen, M. J. Dellarco, (Eds), Pollution in Industrial processes, 126 pp., ACS Symp. Ser., Washington, D.C. 508, 1992.

High heating rate thermal desorption for molecular surface sampling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ovchinnikova, Olga S.; Van Berkel, Gary J.

2016-03-29

A method for analyzing a sample having at least one analyte includes the step of heating the sample at a rate of at least 10.sup.6 K/s to thermally desorb at least one analyte from the sample. The desorbed analyte is collected. The analyte can then be analyzed.

Enhanced spot preparation for liquid extractive sampling and analysis

DOEpatents

Van Berkel, Gary J.; King, Richard C.

2015-09-22

A method for performing surface sampling of an analyte, includes the step of placing the analyte on a stage with a material in molar excess to the analyte, such that analyte-analyte interactions are prevented and the analyte can be solubilized for further analysis. The material can be a matrix material that is mixed with the analyte. The material can be provided on a sample support. The analyte can then be contacted with a solvent to extract the analyte for further processing, such as by electrospray mass spectrometry.

Active Sampling Device for Determining Pollutants in Surface and Pore Water - the In Situ Sampler for Biphasic Water Monitoring

NASA Astrophysics Data System (ADS)

Supowit, Samuel D.; Roll, Isaac B.; Dang, Viet D.; Kroll, Kevin J.; Denslow, Nancy D.; Halden, Rolf U.

2016-02-01

We designed and evaluated an active sampling device, using as analytical targets a family of pesticides purported to contribute to honeybee colony collapse disorder. Simultaneous sampling of bulk water and pore water was accomplished using a low-flow, multi-channel pump to deliver water to an array of solid-phase extraction cartridges. Analytes were separated using either liquid or gas chromatography, and analysis was performed using tandem mass spectrometry (MS/MS). Achieved recoveries of fipronil and degradates in water spiked to nominal concentrations of 0.1, 1, and 10 ng/L ranged from 77 ± 12 to 110 ± 18%. Method detection limits (MDLs) were as low as 0.040-0.8 ng/L. Extraction and quantitation of total fiproles at a wastewater-receiving wetland yielded concentrations in surface water and pore water ranging from 9.9 ± 4.6 to 18.1 ± 4.6 ng/L and 9.1 ± 3.0 to 12.6 ± 2.1 ng/L, respectively. Detected concentrations were statistically indistinguishable from those determined by conventional, more laborious techniques (p > 0.2 for the three most abundant fiproles). Aside from offering time-averaged sampling capabilities for two phases simultaneously with picogram-per-liter MDLs, the novel methodology eliminates the need for water and sediment transport via in situ solid phase extraction.

Fast and selective pressurized liquid extraction with simultaneous in cell clean up for the analysis of alkylphenols and bisphenol A in bivalve molluscs.

PubMed

Salgueiro-González, N; Turnes-Carou, I; Muniategui-Lorenzoa, S; López-Mahía, P; Prada-Rodríguez, D

2012-12-28

A novel and green analytical methodology for the determination of alkylphenols (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol technical mixture) and bisphenol A in bivalve mollusc samples was developed and validated. The method was based on selective pressurized liquid extraction (SPLE) with a simultaneous in cell clean up combined with liquid chromatography–electrospray ionization tandem mass spectrometry in negative mode (LC–ESI-MS/MS). Quantitation was performed by standard addition curves in order to correct matrix effects. The analytical features of the method were satisfactory: relative recoveries varied between 80 and 107% and repeatability and intermediate precision were <20% for all compounds. Uncertainty assessment of measurement was estimated on the basis of an in-house validation according to EURACHEM/CITAC guide. Quantitation limits of the method (MQL) ranged between 0.34 (4-n-octylphenol) and 3.6 ng g(−1) dry weight (nonylphenol). The main advantages of the method are sensitivity, selectivity, automaticity, low volumes of solvents required and low sample analysis time (according with the principles of Green Chemistry). The method was applied to the analysis of mussel samples of Galicia coast (NW of Spain). Nonylphenol and 4-tert-octylphenol were measured in all samples at concentrations between 9.3 and 372 ng g(−1) dw. As an approach, the human daily intake of these compounds was estimated and no risk for human health was found.

Determination of trace levels of benzophenone-type ultra-violet filters in real matrices by bar adsorptive micro-extraction using selective sorbent phases.

PubMed

Almeida, C; Stępkowska, A; Alegre, A; Nogueira, J M F

2013-10-11

Bar adsorptive micro-extraction (BAμE), using selective sorbent phases, followed by liquid desorption in combination with high performance liquid chromatography-diode array detection (BAμE-LD/HPLC-DAD), is proposed for the determination of trace levels of four benzophenone-type UV filters (benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2,4-hydroxybenzophenone and 4-hydroxybenzophenone) in real matrices. By comparing three polymers (P1, P2 and P3) and five activated carbons (AC1, AC2, AC3, AC4 and AC5) phases, P2 (a modified pyrrolidone polymer) and AC4 coatings showed much higher selectivity and capacity through BAμE, where the former offers multiple mechanisms of interaction and faster equilibrium kinetics. Assays performed on 25mL of ultra-pure water samples spiked at the 8.0μg/L level, yielded recoveries ranging from 76.6±8.3% to 103.5±6.4% depending on the sorbent phase used (P2 or AC4), under optimized experimental conditions. The analytical performance showed convenient detection limits (0.3-0.5μg/L) and good linear dynamic ranges (1.0-24.0μg/L) with remarkable determination coefficients (r(2)>0.9969). Excellent repeatability was also achieved through intraday (RSD<13.0%) and interday (RSD<8.9%) experiments. By using the standard addition methodology, the application of the present analytical approach on sea water, wastewater, commercial cosmetic products and urine samples revealed good sensitivity, absence of matrix effects and the occurrence of levels of some benzophenones. The proposed methodology that uses nanostructured particles and operates under the floating sampling technology proved to be a sorption-based static micro-extraction alternative to monitor benzophenone-type UV filters in real matrices. Moreover, is easy to implement, reliable, sensitive, requiring low sample volume and the possibility to choose the most selective sorbent coating according to the target compounds involved. Copyright © 2013. Published by Elsevier B.V.

A Methodology for Conducting Integrative Mixed Methods Research and Data Analyses

PubMed Central

Castro, Felipe González; Kellison, Joshua G.; Boyd, Stephen J.; Kopak, Albert

2011-01-01

Mixed methods research has gained visibility within the last few years, although limitations persist regarding the scientific caliber of certain mixed methods research designs and methods. The need exists for rigorous mixed methods designs that integrate various data analytic procedures for a seamless transfer of evidence across qualitative and quantitative modalities. Such designs can offer the strength of confirmatory results drawn from quantitative multivariate analyses, along with “deep structure” explanatory descriptions as drawn from qualitative analyses. This article presents evidence generated from over a decade of pilot research in developing an integrative mixed methods methodology. It presents a conceptual framework and methodological and data analytic procedures for conducting mixed methods research studies, and it also presents illustrative examples from the authors' ongoing integrative mixed methods research studies. PMID:22167325

Selecting Health Care Improvement Projects: A Methodology Integrating Cause-and-Effect Diagram and Analytical Hierarchy Process.

PubMed

Testik, Özlem Müge; Shaygan, Amir; Dasdemir, Erdi; Soydan, Guray

It is often vital to identify, prioritize, and select quality improvement projects in a hospital. Yet, a methodology, which utilizes experts' opinions with different points of view, is needed for better decision making. The proposed methodology utilizes the cause-and-effect diagram to identify improvement projects and construct a project hierarchy for a problem. The right improvement projects are then prioritized and selected using a weighting scheme of analytical hierarchy process by aggregating experts' opinions. An approach for collecting data from experts and a graphical display for summarizing the obtained information are also provided. The methodology is implemented for improving a hospital appointment system. The top-ranked 2 major project categories for improvements were identified to be system- and accessibility-related causes (45%) and capacity-related causes (28%), respectively. For each of the major project category, subprojects were then ranked for selecting the improvement needs. The methodology is useful in cases where an aggregate decision based on experts' opinions is expected. Some suggestions for practical implementations are provided.

Fast, sensitive, and selective gas chromatography tandem mass spectrometry method for the target analysis of chemical secretions from femoral glands in lizards.

PubMed

Sáiz, Jorge; García-Roa, Roberto; Martín, José; Gómara, Belén

2017-09-08

Chemical signaling is a widespread mode of communication among living organisms that is used to establish social organization, territoriality and/or for mate choice. In lizards, femoral and precloacal glands are important sources of chemical signals. These glands protrude chemical secretions used to mark territories and also, to provide valuable information from the bearer to other individuals. Ecologists have studied these chemical secretions for decades in order to increase the knowledge of chemical communication in lizards. Although several studies have focused on the chemical analysis of these secretions, there is a lack of faster, more sensitive and more selective analytical methodologies for their study. In this work a new GC coupled to tandem triple quadrupole MS (GC-QqQ (MS/MS)) methodology is developed and proposed for the target study of 12 relevant compounds often found in lizard secretions (i.e. 1-hexadecanol, palmitic acid, 1-octadecanol, oleic acid, stearic acid, 1-tetracosanol, squalene, cholesta-3,5-diene, α-tocopherol, cholesterol, ergosterol and campesterol). The method baseline-separated the analytes in less than 7min, with instrumental limits of detection ranging from 0.04 to 6.0ng/mL. It was possible to identify differences in the composition of the samples from the lizards analyzed, which depended on the species, the habitat occupied and the diet of the individuals. Moreover, α-tocopherol has been determined for the first time in a lizard species, which was thought to lack its expression in chemical secretions. Globally, the methodology has been proven to be a valuable alternative to other published methods with important improvements in terms of analysis time, sensitivity, and selectivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Model Analytical Development for Physical, Chemical, and Biological Characterization of Momordica charantia Vegetable Drug

PubMed Central

Guimarães, Geovani Pereira; Santos, Ravely Lucena; Júnior, Fernando José de Lima Ramos; da Silva, Karla Monik Alves; de Souza, Fabio Santos

2016-01-01

Momordica charantia is a species cultivated throughout the world and widely used in folk medicine, and its medicinal benefits are well documented, especially its pharmacological properties, including antimicrobial activities. Analytical methods have been used to aid in the characterization of compounds derived from plant drug extracts and their products. This paper developed a methodological model to evaluate the integrity of the vegetable drug M. charantia in different particle sizes, using different analytical methods. M. charantia was collected in the semiarid region of Paraíba, Brazil. The herbal medicine raw material derived from the leaves and fruits in different particle sizes was analyzed using thermoanalytical techniques as thermogravimetry (TG) and differential thermal analysis (DTA), pyrolysis coupled to gas chromatography/mass spectrometry (PYR-GC/MS), and nuclear magnetic resonance (1H NMR), in addition to the determination of antimicrobial activity. The different particle surface area among the samples was differentiated by the techniques. DTA and TG were used for assessing thermal and kinetic parameters and PYR-GC/MS was used for degradation products chromatographic identification through the pyrograms. The infusions obtained from the fruit and leaves of Momordica charantia presented antimicrobial activity. PMID:27579215

Single-scan 2D NMR: An Emerging Tool in Analytical Spectroscopy

PubMed Central

Giraudeau, Patrick; Frydman, Lucio

2016-01-01

Two-dimensional Nuclear Magnetic Resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing an increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago a so-called “ultrafast” (UF) approach was proposed, capable to deliver arbitrary 2D NMR spectra involving any kind of homo- or hetero-nuclear correlations, in a single scan. During the intervening years the performance of this sub-second 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool witnessing an expanded scope of applications. The present reviews summarizes the principles and the main developments which have contributed to the success of this approach, and focuses on applications which have been recently demonstrated in various areas of analytical chemistry –from the real time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications. PMID:25014342

COMPARISON OF ANALYTICAL METHODS FOR THE MEASUREMENT OF NON-VIABLE BIOLOGICAL PM

EPA Science Inventory

The paper describes a preliminary research effort to develop a methodology for the measurement of non-viable biologically based particulate matter (PM), analyzing for mold, dust mite, and ragweed antigens and endotoxins. Using a comparison of analytical methods, the research obj...

Cognitive-Developmental and Behavior-Analytic Theories: Evolving into Complementarity

ERIC Educational Resources Information Center

Overton, Willis F.; Ennis, Michelle D.

2006-01-01

Historically, cognitive-developmental and behavior-analytic approaches to the study of human behavior change and development have been presented as incompatible alternative theoretical and methodological perspectives. This presumed incompatibility has been understood as arising from divergent sets of metatheoretical assumptions that take the form…

Bioinspired Methodology for Artificial Olfaction

PubMed Central

Raman, Baranidharan; Hertz, Joshua L.; Benkstein, Kurt D.; Semancik, Steve

2008-01-01

Artificial olfaction is a potential tool for noninvasive chemical monitoring. Application of “electronic noses” typically involves recognition of “pretrained” chemicals, while long-term operation and generalization of training to allow chemical classification of “unknown” analytes remain challenges. The latter analytical capability is critically important, as it is unfeasible to pre-expose the sensor to every analyte it might encounter. Here, we demonstrate a biologically inspired approach where the recognition and generalization problems are decoupled and resolved in a hierarchical fashion. Analyte composition is refined in a progression from general (e.g., target is a hydrocarbon) to precise (e.g., target is ethane), using highly optimized response features for each step. We validate this approach using a MEMS-based chemiresistive microsensor array. We show that this approach, a unique departure from existing methodologies in artificial olfaction, allows the recognition module to better mitigate sensor-aging effects and to better classify unknowns, enhancing the utility of chemical sensors for real-world applications. PMID:18855409

Analytical methodology for determination of helicopter IFR precision approach requirements. [pilot workload and acceptance level

NASA Technical Reports Server (NTRS)

Phatak, A. V.

1980-01-01

A systematic analytical approach to the determination of helicopter IFR precision approach requirements is formulated. The approach is based upon the hypothesis that pilot acceptance level or opinion rating of a given system is inversely related to the degree of pilot involvement in the control task. A nonlinear simulation of the helicopter approach to landing task incorporating appropriate models for UH-1H aircraft, the environmental disturbances and the human pilot was developed as a tool for evaluating the pilot acceptance hypothesis. The simulated pilot model is generic in nature and includes analytical representation of the human information acquisition, processing, and control strategies. Simulation analyses in the flight director mode indicate that the pilot model used is reasonable. Results of the simulation are used to identify candidate pilot workload metrics and to test the well known performance-work-load relationship. A pilot acceptance analytical methodology is formulated as a basis for further investigation, development and validation.

Introduction of agarose gel as a green membrane in electromembrane extraction: An efficient procedure for the extraction of basic drugs with a wide range of polarities.

PubMed

Tabani, Hadi; Asadi, Sakine; Nojavan, Saeed; Parsa, Mitra

2017-05-12

Developing green methods for analyte extraction is one of the most important topics in the field of sample preparation. In this study, for the first time, agarose gel was used as membrane in electromembrane extraction (EME) without using any organic solvent, for the extraction of four model basic drugs (rivastigmine (RIV), verapamil (VER), amlodipine (AML), and morphine (MOR)) with a wide polarity window (log P from 0.43 to 3.7). Different variables playing vital roles in the proposed method were evaluated and optimized. As a driving force, a 25V electrical field was applied to make the analyte migrate from sample solution with pH 7.0, through the agarose gel 3% (w/v) with 5mm thickness, into an acceptor phase (AP) with pH 2.0. The best extraction efficiency was obtained with an extraction duration of 25min. With this new methodology, MOR with high polarity (log P=0.43) was efficiently extracted without using any carrier or ion pair reagents. Limits of detection (LODs) and quantification (LOQs) were in the ranges of 1.5-1.8ngmL -1 and 5.0-6.0ngmL -1 , respectively. Finally, the proposed method was successfully applied to determine concentrations of the model drugs in the wastewater sample. Copyright © 2017 Elsevier B.V. All rights reserved.

Insufficient filling of vacuum tubes as a cause of microhemolysis and elevated serum lactate dehydrogenase levels. Use of a data-mining technique in evaluation of questionable laboratory test results.

PubMed

Tamechika, Yoshie; Iwatani, Yoshinori; Tohyama, Kaoru; Ichihara, Kiyoshi

2006-01-01

Experienced physicians noted unexpectedly elevated concentrations of lactate dehydrogenase in some patient samples, but quality control specimens showed no bias. To evaluate this problem, we used a "latent reference individual extraction method", designed to obtain reference intervals from a laboratory database by excluding individuals who have abnormal results for basic analytes other than the analyte in question, in this case lactate dehydrogenase. The reference interval derived for the suspected year was 264-530 U/L, while that of the previous year was 248-495 U/L. The only change we found was the introduction of an order entry system, which requests precise sampling volumes rather than complete filling of vacuum tubes. The effect of vacuum persistence was tested using ten freshly drawn blood samples. Compared with complete filling, 1/5 filling resulted in average elevations of lactate dehydrogenase, aspartic aminotransferase, and potassium levels of 8.0%, 3.8%, and 3.4%, respectively (all p<0.01). Microhemolysis was confirmed using a urine stick method. The length of time before centrifugation determined the degree of hemolysis, while vacuum during centrifugation did not affect it. Microhemolysis is the probable cause of the suspected pseudo-elevation noted by the physicians. Data-mining methodology represents a valuable tool for monitoring long-term bias in laboratory results.

Gas chromatographic–mass spectrometric fragmentation study of phytoestrogens as their trimethylsilyl derivatives: Identification in soy milk and wastewater samples

USGS Publications Warehouse

Ferrar, Imma; Barber, Larry B.; Thurman, E. Michael

2009-01-01

An analytical method for the identification of eight plant phytoestrogens (biochanin A, coumestrol, daidzein, equol, formononetin, glycitein, genistein and prunetin) in soy products and wastewater samples was developed using gas chromatography coupled with ion trap mass spectrometry (GC/MS–MS). The phytoestrogens were derivatized as their trimethylsilyl ethers with trimethylchlorosilane (TMCS) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). The phytoestrogens were isolated from all samples with liquid–liquid extraction using ethyl acetate. Daidzein-d4 and genistein-d4 labeled standards were used as internal standards before extraction and derivatization. The fragmentation patterns of the phytoestrogens were investigated by isolating and fragmenting the precursor ions in the ion-trap and a typical fragmentation involved the loss of a methyl and a carbonyl group. Two characteristic fragment ions for each analyte were chosen for identification and confirmation. The developed methodology was applied to the identification and confirmation of phytoestrogens in soy milk, in wastewater effluent from a soy-milk processing plant, and in wastewater (influent and effluent) from a treatment plant. Detected concentrations of genistein ranged from 50,000 μg/L and 2000 μg/L in soy milk and in wastewater from a soy-plant, respectively, to 20 μg/L and <1 μg/L for influent and effluent from a wastewater treatment plant, respectively.

Human exposure to Bisphenol A and liver health status: Quantification of urinary and circulating levels by LC-MS/MS.

PubMed

Nicolucci, Carla; Errico, Sonia; Federico, Alessandro; Dallio, Marcello; Loguercio, Carmelina; Diano, Nadia

2017-06-05

A selective and highly sensitive analytical methodology for determination of Bisphenol A in human plasma was developed and validated. The method was based on selective liquid/solid extraction, combined with liquid chromatography-electrospray ionization tandem mass spectrometry in the multiple reaction monitoring mode and negative ionization. The linearity of the detector response was verified in human plasma over the concentration range 0.100-200ngmL -1 . The detection limit was 0.03ngmL -1 and the quantification limit was 0.100ngmL -1 . The analytical features of the proposed in-house validated method were satisfactory: precision was <10% and recoveries were around 84-104%. The matrix effect was studied and compensated using deuterated labeled standard. The applicability of the proposed method was demonstrated analyzing human plasma samples from individuals affected by non-alcoholic fatty liver disease. Bisphenol A was detected above the detection limit in all samples. The data show a persistence of unconjugated Bisphenol A levels in plasma and indicate a chronic Bisphenol A exposure of the target organ, suggesting an association between liver health status and Bisphenol A exposure. The results from our study are valuable for further investigation with large sample size and longitudinal study designs, necessary to confirm the observed association. Copyright © 2017 Elsevier B.V. All rights reserved.

A highly selective nanocomposite based on MIP for curcumin trace levels quantification in food samples and human plasma following optimization by central composite design.

PubMed

Bahrani, Sonia; Ghaedi, Mehrorang; Khoshnood Mansoorkhani, Mohammad Javad; Ostovan, Abbas

2017-01-01

A selective and rapid method was developed for quantification of curcumin in human plasma and food samples using molecularly imprinted magnetic multiwalled carbon nanotubes (MMWCNTs) which was characterized with EDX and FESEM. The role of sorbent mass, volume of eluent and sonication time on response in solid phase microextraction procedure were optimized by central composite design (CCD) combined with response surface methodology (RSM) using Statistica. Preliminary experiments reveal that among different solvents, methanol:dimethyl sulfoxide (4:1V/V) led to efficient and quantitative elution of analyte. A reversed-phase high performance liquid chromatographic technique with UV detection (HPLC-UV) was applied for detection of curcumin content. The assay procedure involves chromatographic separation on analytical Nucleosil C18 column (250×4.6mm I.D., 5μm particle size) at ambient temperature with acetonitrile-water adjusted at pH=4.0 (20:80, v/v) as mobile phase at flow rate of 1.0mLmin -1 , while UV detector was set at 420nm. Under optimized conditions, the method demonstrated linear calibration curve with good detection limit (0.028ngmL -1 ) and R 2 =0.9983. The proposed method was successfully applied to biological fluid and food samples including ginger powder, curry powder, and turmeric powder. Copyright © 2016. Published by Elsevier B.V.

Bias Assessment of General Chemistry Analytes using Commutable Samples.

PubMed

Koerbin, Gus; Tate, Jillian R; Ryan, Julie; Jones, Graham Rd; Sikaris, Ken A; Kanowski, David; Reed, Maxine; Gill, Janice; Koumantakis, George; Yen, Tina; St John, Andrew; Hickman, Peter E; Simpson, Aaron; Graham, Peter

2014-11-01

Harmonisation of reference intervals for routine general chemistry analytes has been a goal for many years. Analytical bias may prevent this harmonisation. To determine if analytical bias is present when comparing methods, the use of commutable samples, or samples that have the same properties as the clinical samples routinely analysed, should be used as reference samples to eliminate the possibility of matrix effect. The use of commutable samples has improved the identification of unacceptable analytical performance in the Netherlands and Spain. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has undertaken a pilot study using commutable samples in an attempt to determine not only country specific reference intervals but to make them comparable between countries. Australia and New Zealand, through the Australasian Association of Clinical Biochemists (AACB), have also undertaken an assessment of analytical bias using commutable samples and determined that of the 27 general chemistry analytes studied, 19 showed sufficiently small between method biases as to not prevent harmonisation of reference intervals. Application of evidence based approaches including the determination of analytical bias using commutable material is necessary when seeking to harmonise reference intervals.

Microfluidic-Based sample chips for radioactive solutions

DOE PAGES

Tripp, J. L.; Law, J. D.; Smith, T. E.; ...

2015-01-01

Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument wouldmore » greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.« less

Assessment of concentrations of trace elements in ground water and soil at the Small-Arms Firing Range, Shaw Air Force Base, South Carolina

USGS Publications Warehouse

Landmeyer, J.E.

1994-01-01

Ground-water samples were collected from four shallow water-table aquifer observation wells beneath the Small-Arms Firing Range study area at Shaw Air Force Base. Water-chemistry analyses indicated that total lead concentrations in shallow ground water beneath the study area do not exceed the U.S. Environmental Protection Agency maximum contaminant level established for lead in drinking water (0.05 milligrams per liter). All other trace element total concentrations in ground water beneath the study area were at or below the detection limit of the analytical methodology.

Population Studies of Intact Vitamin D Binding Protein by Affinity Capture ESI-TOF-MS

PubMed Central

Borges, Chad R.; Jarvis, Jason W.; Oran, Paul E.; Rogers, Stephen P.; Nelson, Randall W.

2008-01-01

Blood plasma proteins with molecular weights greater than approximately 30 kDa are refractory to comprehensive, high-throughput qualitative characterization of microheterogeneity across human populations. Analytical techniques for obtaining high mass resolution for targeted, intact protein characterization and, separately, high sample throughput exist, but efficient means of coupling these assay characteristics remain rather limited. This article discusses the impetus for analyzing intact proteins in a targeted manner across populations and describes the methodology required to couple mass spectrometric immunoassay with electrospray ionization mass spectrometry for the purpose of qualitatively characterizing a prototypical large plasma protein, vitamin D binding protein, across populations. PMID:19137103

Closed-loop, pilot/vehicle analysis of the approach and landing task

NASA Technical Reports Server (NTRS)

Schmidt, D. K.; Anderson, M. R.

1985-01-01

Optimal-control-theoretic modeling and frequency-domain analysis is the methodology proposed to evaluate analytically the handling qualities of higher-order manually controlled dynamic systems. Fundamental to the methodology is evaluating the interplay between pilot workload and closed-loop pilot/vehicle performance and stability robustness. The model-based metric for pilot workload is the required pilot phase compensation. Pilot/vehicle performance and loop stability is then evaluated using frequency-domain techniques. When these techniques were applied to the flight-test data for thirty-two highly-augmented fighter configurations, strong correlation was obtained between the analytical and experimental results.

Hybrid experimental/analytical models of structural dynamics - Creation and use for predictions

NASA Technical Reports Server (NTRS)

Balmes, Etienne

1993-01-01

An original complete methodology for the construction of predictive models of damped structural vibrations is introduced. A consistent definition of normal and complex modes is given which leads to an original method to accurately identify non-proportionally damped normal mode models. A new method to create predictive hybrid experimental/analytical models of damped structures is introduced, and the ability of hybrid models to predict the response to system configuration changes is discussed. Finally a critical review of the overall methodology is made by application to the case of the MIT/SERC interferometer testbed.

Big data analytics in healthcare: promise and potential.

PubMed

Raghupathi, Wullianallur; Raghupathi, Viju

2014-01-01

To describe the promise and potential of big data analytics in healthcare. The paper describes the nascent field of big data analytics in healthcare, discusses the benefits, outlines an architectural framework and methodology, describes examples reported in the literature, briefly discusses the challenges, and offers conclusions. The paper provides a broad overview of big data analytics for healthcare researchers and practitioners. Big data analytics in healthcare is evolving into a promising field for providing insight from very large data sets and improving outcomes while reducing costs. Its potential is great; however there remain challenges to overcome.

Structural Sizing Methodology for the Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN) System

NASA Technical Reports Server (NTRS)

Jones, Thomas C.; Dorsey, John T.; Doggett, William R.

2015-01-01

The Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN) is a versatile long-reach robotic manipulator that is currently being tested at NASA Langley Research Center. TALISMAN is designed to be highly mass-efficient and multi-mission capable, with applications including asteroid retrieval and manipulation, in-space servicing, and astronaut and payload positioning. The manipulator uses a modular, periodic, tension-compression design that lends itself well to analytical modeling. Given the versatility of application for TALISMAN, a structural sizing methodology was developed that could rapidly assess mass and configuration sensitivities for any specified operating work space, applied loads and mission requirements. This methodology allows the systematic sizing of the key structural members of TALISMAN, which include the truss arm links, the spreaders and the tension elements. This paper summarizes the detailed analytical derivations and methodology that support the structural sizing approach and provides results from some recent TALISMAN designs developed for current and proposed mission architectures.

Background for Joint Systems Aspects of AIR 6000

DTIC Science & Technology

2000-04-01

Checkland’s Soft Systems Methodology [7, 8,9]. The analytical techniques that are proposed for joint systems work are based on calculating probability...Supporting Global Interests 21 DSTO-CR-0155 SLMP Structural Life Management Plan SOW Stand-Off Weapon SSM Soft Systems Methodology UAV Uninhabited Aerial... Systems Methodology in Action, John Wiley & Sons, Chichester, 1990. [101 Pearl, Judea, Probabilistic Reasoning in Intelligent Systems: Networks of Plausible

Defining And Characterizing Sample Representativeness For DWPF Melter Feed Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shine, E. P.; Poirier, M. R.

2013-10-29

Representative sampling is important throughout the Defense Waste Processing Facility (DWPF) process, and the demonstrated success of the DWPF process to achieve glass product quality over the past two decades is a direct result of the quality of information obtained from the process. The objective of this report was to present sampling methods that the Savannah River Site (SRS) used to qualify waste being dispositioned at the DWPF. The goal was to emphasize the methodology, not a list of outcomes from those studies. This methodology includes proven methods for taking representative samples, the use of controlled analytical methods, and datamore » interpretation and reporting that considers the uncertainty of all error sources. Numerous sampling studies were conducted during the development of the DWPF process and still continue to be performed in order to evaluate options for process improvement. Study designs were based on use of statistical tools applicable to the determination of uncertainties associated with the data needs. Successful designs are apt to be repeated, so this report chose only to include prototypic case studies that typify the characteristics of frequently used designs. Case studies have been presented for studying in-tank homogeneity, evaluating the suitability of sampler systems, determining factors that affect mixing and sampling, comparing the final waste glass product chemical composition and durability to that of the glass pour stream sample and other samples from process vessels, and assessing the uniformity of the chemical composition in the waste glass product. Many of these studies efficiently addressed more than one of these areas of concern associated with demonstrating sample representativeness and provide examples of statistical tools in use for DWPF. The time when many of these designs were implemented was in an age when the sampling ideas of Pierre Gy were not as widespread as they are today. Nonetheless, the engineers and statisticians used carefully thought out designs that systematically and economically provided plans for data collection from the DWPF process. Key shared features of the sampling designs used at DWPF and the Gy sampling methodology were the specification of a standard for sample representativeness, an investigation that produced data from the process to study the sampling function, and a decision framework used to assess whether the specification was met based on the data. Without going into detail with regard to the seven errors identified by Pierre Gy, as excellent summaries are readily available such as Pitard [1989] and Smith [2001], SRS engineers understood, for example, that samplers can be biased (Gy's extraction error), and developed plans to mitigate those biases. Experiments that compared installed samplers with more representative samples obtained directly from the tank may not have resulted in systematically partitioning sampling errors into the now well-known error categories of Gy, but did provide overall information on the suitability of sampling systems. Most of the designs in this report are related to the DWPF vessels, not the large SRS Tank Farm tanks. Samples from the DWPF Slurry Mix Evaporator (SME), which contains the feed to the DWPF melter, are characterized using standardized analytical methods with known uncertainty. The analytical error is combined with the established error from sampling and processing in DWPF to determine the melter feed composition. This composition is used with the known uncertainty of the models in the Product Composition Control System (PCCS) to ensure that the wasteform that is produced is comfortably within the acceptable processing and product performance region. Having the advantage of many years of processing that meets the waste glass product acceptance criteria, the DWPF process has provided a considerable amount of data about itself in addition to the data from many special studies. Demonstrating representative sampling directly from the large Tank Farm tanks is a difficult, if not unsolvable enterprise due to limited accessibility. However, the consistency and the adequacy of sampling and mixing at SRS could at least be studied under the controlled process conditions based on samples discussed by Ray and others [2012a] in Waste Form Qualification Report (WQR) Volume 2 and the transfers from Tanks 40H and 51H to the Sludge Receipt and Adjustment Tank (SRAT) within DWPF. It is important to realize that the need for sample representativeness becomes more stringent as the material gets closer to the melter, and the tanks within DWPF have been studied extensively to meet those needs.« less

Hierarchical Analytical Approaches for Unraveling the Composition of Proprietary Mixtures

EPA Pesticide Factsheets

The composition of commercial mixtures including pesticide inert ingredients, aircraft deicers, and aqueous film-forming foam (AFFF) formulations, and by analogy, fracking fluids, are proprietary. Quantitative analytical methodologies can only be developed for mixture components once their identities are known. Because proprietary mixtures may contain volatile and non-volatile components, a hierarchy of analytical methods is often required for the full identification of all proprietary mixture components.

Application of Characterization, Modeling, and Analytics Towards Understanding Process Structure Linkages in Metallic 3D Printing (Postprint)

DTIC Science & Technology

2017-08-01

of metallic additive manufacturing processes and show that combining experimental data with modelling and advanced data processing and analytics...manufacturing processes and show that combining experimental data with modelling and advanced data processing and analytics methods will accelerate that...geometries, we develop a methodology that couples experimental data and modelling to convert the scan paths into spatially resolved local thermal histories

Collaborative Visual Analytics: A Health Analytics Approach to Injury Prevention

PubMed Central

Fisher, Brian; Smith, Jennifer; Pike, Ian

2017-01-01

Background: Accurate understanding of complex health data is critical in order to deal with wicked health problems and make timely decisions. Wicked problems refer to ill-structured and dynamic problems that combine multidimensional elements, which often preclude the conventional problem solving approach. This pilot study introduces visual analytics (VA) methods to multi-stakeholder decision-making sessions about child injury prevention; Methods: Inspired by the Delphi method, we introduced a novel methodology—group analytics (GA). GA was pilot-tested to evaluate the impact of collaborative visual analytics on facilitating problem solving and supporting decision-making. We conducted two GA sessions. Collected data included stakeholders’ observations, audio and video recordings, questionnaires, and follow up interviews. The GA sessions were analyzed using the Joint Activity Theory protocol analysis methods; Results: The GA methodology triggered the emergence of ‘common ground’ among stakeholders. This common ground evolved throughout the sessions to enhance stakeholders’ verbal and non-verbal communication, as well as coordination of joint activities and ultimately collaboration on problem solving and decision-making; Conclusions: Understanding complex health data is necessary for informed decisions. Equally important, in this case, is the use of the group analytics methodology to achieve ‘common ground’ among diverse stakeholders about health data and their implications. PMID:28895928

Dental and dental hygiene students' diagnostic accuracy in oral radiology: effect of diagnostic strategy and instructional method.

PubMed

Baghdady, Mariam T; Carnahan, Heather; Lam, Ernest W N; Woods, Nicole N

2014-09-01

There has been much debate surrounding diagnostic strategies and the most appropriate training models for novices in oral radiology. It has been argued that an analytic approach, using a step-by-step analysis of the radiographic features of an abnormality, is ideal. Alternative research suggests that novices can successfully employ non-analytic reasoning. Many of these studies do not take instructional methodology into account. This study evaluated the effectiveness of non-analytic and analytic strategies in radiographic interpretation and explored the relationship between instructional methodology and diagnostic strategy. Second-year dental and dental hygiene students were taught four radiographic abnormalities using basic science instructions or a step-by-step algorithm. The students were tested on diagnostic accuracy and memory immediately after learning and one week later. A total of seventy-three students completed both immediate and delayed sessions and were included in the analysis. Students were randomly divided into two instructional conditions: one group provided a diagnostic hypothesis for the image and then identified specific features to support it, while the other group first identified features and then provided a diagnosis. Participants in the diagnosis-first condition (non-analytic reasoning) had higher diagnostic accuracy then those in the features-first condition (analytic reasoning), regardless of their learning condition. No main effect of learning condition or interaction with diagnostic strategy was observed. Educators should be mindful of the potential influence of analytic and non-analytic approaches on the effectiveness of the instructional method.

Advanced statistical methods for improved data analysis of NASA astrophysics missions

NASA Technical Reports Server (NTRS)

Feigelson, Eric D.

1992-01-01

The investigators under this grant studied ways to improve the statistical analysis of astronomical data. They looked at existing techniques, the development of new techniques, and the production and distribution of specialized software to the astronomical community. Abstracts of nine papers that were produced are included, as well as brief descriptions of four software packages. The articles that are abstracted discuss analytical and Monte Carlo comparisons of six different linear least squares fits, a (second) paper on linear regression in astronomy, two reviews of public domain software for the astronomer, subsample and half-sample methods for estimating sampling distributions, a nonparametric estimation of survival functions under dependent competing risks, censoring in astronomical data due to nondetections, an astronomy survival analysis computer package called ASURV, and improving the statistical methodology of astronomical data analysis.

Application of statistical experimental design to the optimisation of microextraction by packed sorbent for the analysis of nonsteroidal anti-inflammatory drugs in human urine by ultra-high pressure liquid chromatography.

PubMed

Magiera, Sylwia; Gülmez, Şefika; Michalik, Aleksandra; Baranowska, Irena

2013-08-23

A new approach based on microextraction by packed sorbent (MEPS) and a reversed-phase ultra-high pressure liquid chromatography (UHPLC) method was developed and validated for the determination and quantification of nonsteroidal anti-inflammatory drugs (NSAIDs) (acetylsalicylic acid, ketoprofen, diclofenac, naproxen and ibuprofen) in human urine. The important factors that could influence the extraction were previously screened using the Plackett-Burman design approach. The optimal MEPS extraction conditions were obtained using C18 phase as a sorbent, small sample volume (20μL) and a short time period (approximately 5min) for the entire sample preparation step. The analytes were separated on a core-shell column (Poroshell 120 EC-C18; 100mm×3.0mm; 2.7μm) using a binary mobile phase composed of aqueous 0.1% trifluoroacetic acid and acetonitrile in the gradient elution mode (4.5min of analysis time). The analytical method was fully validated based on linearity, limits of detection (LOD), limits of quantification (LOQ), inter- and intra-day precision and accuracy, and extraction yield. Under optimised conditions, excellent linearity (R(2)>0.9991), limits of detection (1.07-16.2ngmL(-1)) and precision (0.503-9.15% RSD) were observed for the target drugs. The average absolute recoveries of the analysed compounds extracted from the urine samples were 89.4-107%. The proposed method was also applied to the analysis of NSAIDs in human urine. The new approach offers an attractive alternative for the analysis of selected drugs from urine samples, providing several advantages including fewer sample preparation steps, faster sample throughput and ease of performance compared to traditional methodologies. Copyright © 2013 Elsevier B.V. All rights reserved.