Detecting declines in the abundance of a bull trout (Salvelinus confluentus) population: Understanding the accuracy, precision, and costs of our efforts

USGS Publications Warehouse

Al-Chokhachy, R.; Budy, P.; Conner, M.

2009-01-01

Using empirical field data for bull trout (Salvelinus confluentus), we evaluated the trade-off between power and sampling effort-cost using Monte Carlo simulations of commonly collected mark-recapture-resight and count data, and we estimated the power to detect changes in abundance across different time intervals. We also evaluated the effects of monitoring different components of a population and stratification methods on the precision of each method. Our results illustrate substantial variability in the relative precision, cost, and information gained from each approach. While grouping estimates by age or stage class substantially increased the precision of estimates, spatial stratification of sampling units resulted in limited increases in precision. Although mark-resight methods allowed for estimates of abundance versus indices of abundance, our results suggest snorkel surveys may be a more affordable monitoring approach across large spatial scales. Detecting a 25% decline in abundance after 5 years was not possible, regardless of technique (power = 0.80), without high sampling effort (48% of study site). Detecting a 25% decline was possible after 15 years, but still required high sampling efforts. Our results suggest detecting moderate changes in abundance of freshwater salmonids requires considerable resource and temporal commitments and highlight the difficulties of using abundance measures for monitoring bull trout populations.

Detection methods and performance criteria for genetically modified organisms.

PubMed

Bertheau, Yves; Diolez, Annick; Kobilinsky, André; Magin, Kimberly

2002-01-01

Detection methods for genetically modified organisms (GMOs) are necessary for many applications, from seed purity assessment to compliance of food labeling in several countries. Numerous analytical methods are currently used or under development to support these needs. The currently used methods are bioassays and protein- and DNA-based detection protocols. To avoid discrepancy of results between such largely different methods and, for instance, the potential resulting legal actions, compatibility of the methods is urgently needed. Performance criteria of methods allow evaluation against a common standard. The more-common performance criteria for detection methods are precision, accuracy, sensitivity, and specificity, which together specifically address other terms used to describe the performance of a method, such as applicability, selectivity, calibration, trueness, precision, recovery, operating range, limit of quantitation, limit of detection, and ruggedness. Performance criteria should provide objective tools to accept or reject specific methods, to validate them, to ensure compatibility between validated methods, and be used on a routine basis to reject data outside an acceptable range of variability. When selecting a method of detection, it is also important to consider its applicability, its field of applications, and its limitations, by including factors such as its ability to detect the target analyte in a given matrix, the duration of the analyses, its cost effectiveness, and the necessary sample sizes for testing. Thus, the current GMO detection methods should be evaluated against a common set of performance criteria.

Statistical behavior of ten million experimental detection limits

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-02-01

Using a lab-constructed laser-excited fluorimeter, together with bootstrapping methodology, the authors have generated many millions of experimental linear calibration curves for the detection of rhodamine 6G tetrafluoroborate in ethanol solutions. The detection limits computed from them are in excellent agreement with both previously published theory and with comprehensive Monte Carlo computer simulations. Currie decision levels and Currie detection limits, each in the theoretical, chemical content domain, were found to be simply scaled reciprocals of the non-centrality parameter of the non-central t distribution that characterizes univariate linear calibration curves that have homoscedastic, additive Gaussian white noise. Accurate and precise estimates of the theoretical, content domain Currie detection limit for the experimental system, with 5% (each) probabilities of false positives and false negatives, are presented.

Achieving the Heisenberg limit in quantum metrology using quantum error correction.

PubMed

Zhou, Sisi; Zhang, Mengzhen; Preskill, John; Jiang, Liang

2018-01-08

Quantum metrology has many important applications in science and technology, ranging from frequency spectroscopy to gravitational wave detection. Quantum mechanics imposes a fundamental limit on measurement precision, called the Heisenberg limit, which can be achieved for noiseless quantum systems, but is not achievable in general for systems subject to noise. Here we study how measurement precision can be enhanced through quantum error correction, a general method for protecting a quantum system from the damaging effects of noise. We find a necessary and sufficient condition for achieving the Heisenberg limit using quantum probes subject to Markovian noise, assuming that noiseless ancilla systems are available, and that fast, accurate quantum processing can be performed. When the sufficient condition is satisfied, a quantum error-correcting code can be constructed that suppresses the noise without obscuring the signal; the optimal code, achieving the best possible precision, can be found by solving a semidefinite program.

Achieving metrological precision limits through postselection

NASA Astrophysics Data System (ADS)

Alves, G. Bié; Pimentel, A.; Hor-Meyll, M.; Walborn, S. P.; Davidovich, L.; Filho, R. L. de Matos

2017-01-01

Postselection strategies have been proposed with the aim of amplifying weak signals, which may help to overcome detection thresholds associated with technical noise in high-precision measurements. Here we use an optical setup to experimentally explore two different postselection protocols for the estimation of a small parameter: a weak-value amplification procedure and an alternative method that does not provide amplification but nonetheless is shown to be more robust for the sake of parameter estimation. Each technique leads approximately to the saturation of quantum limits for the estimation precision, expressed by the Cramér-Rao bound. For both situations, we show that parameter estimation is improved when the postselection statistics are considered together with the measurement device.

BEAMing LAMP: single-molecule capture and on-bead isothermal amplification for digital detection of hepatitis C virus in plasma.

PubMed

Chen, Jiyun; Xu, Xiaomin; Huang, Zhimei; Luo, Yuan; Tang, Lijuan; Jiang, Jian-Hui

2018-01-02

A novel dNAD platform (BEAMing LAMP) by combining emulsion micro-reactors, single-molecule magnetic capture and on-bead loop-mediated isothermal amplification has been developed for DNA detection, which enables absolute and high-precision quantification of a target with a detection limit of 300 copies.

Quality control of test iodine in urine by spectrophotometry UV-Vis

NASA Astrophysics Data System (ADS)

Huda, Thorikul; Nafisah, Durotun; Kumorowulan, Suryati; Lestari, Sri

2017-12-01

A quality control of iodine test in with UV-Vis spectrophotometry has been done. The purpose of this research is to find out whether the test results of samples conducted by Clinical Office of Research and Development Of GAKI (BP2GAKI) laboratory are still controlled, feasible and reliable, and still consistent over time, as indicated by the control chart. Quality control parameters are linearity, precision, accuracy, limit of detection, and limit of quantification. Based on the quality control that has been done, obtained linearity (r)= -0.9974, the detection limit and the limit of quantitation are respectively 2.26 µg/L and 7.54 µg/L, while the accuracy is calculated by %recovery and precision with value % RSD are 97.4161% and 1.7136% respectively. The quality control of iodine test in urine using the control chart shows excellent or stable results for 30 days and no variation of the results is very different for each day.

Capacity and precision in an animal model of visual short-term memory.

PubMed

Lara, Antonio H; Wallis, Jonathan D

2012-03-14

Temporary storage of information in visual short-term memory (VSTM) is a key component of many complex cognitive abilities. However, it is highly limited in capacity. Understanding the neurophysiological nature of this capacity limit will require a valid animal model of VSTM. We used a multiple-item color change detection task to measure macaque monkeys' VSTM capacity. Subjects' performance deteriorated and reaction times increased as a function of the number of items in memory. Additionally, we measured the precision of the memory representations by varying the distance between sample and test colors. In trials with similar sample and test colors, subjects made more errors compared to trials with highly discriminable colors. We modeled the error distribution as a Gaussian function and used this to estimate the precision of VSTM representations. We found that as the number of items in memory increases the precision of the representations decreases dramatically. Additionally, we found that focusing attention on one of the objects increases the precision with which that object is stored and degrades the precision of the remaining. These results are in line with recent findings in human psychophysics and provide a solid foundation for understanding the neurophysiological nature of the capacity limit of VSTM.

Quantitative analysis of sitagliptin using the (19)F-NMR method: a universal technique for fluorinated compound detection.

PubMed

Zhang, Fen-Fen; Jiang, Meng-Hong; Sun, Lin-Lin; Zheng, Feng; Dong, Lei; Shah, Vishva; Shen, Wen-Bin; Ding, Ya

2015-01-07

To expand the application scope of nuclear magnetic resonance (NMR) technology in quantitative analysis of pharmaceutical ingredients, (19)F nuclear magnetic resonance ((19)F-NMR) spectroscopy has been employed as a simple, rapid, and reproducible approach for the detection of a fluorine-containing model drug, sitagliptin phosphate monohydrate (STG). ciprofloxacin (Cipro) has been used as the internal standard (IS). Influential factors, including the relaxation delay time (d1) and pulse angle, impacting the accuracy and precision of spectral data are systematically optimized. Method validation has been carried out in terms of precision and intermediate precision, linearity, limit of detection (LOD) and limit of quantification (LOQ), robustness, and stability. To validate the reliability and feasibility of the (19)F-NMR technology in quantitative analysis of pharmaceutical analytes, the assay result has been compared with that of (1)H-NMR. The statistical F-test and student t-test at 95% confidence level indicate that there is no significant difference between these two methods. Due to the advantages of (19)F-NMR, such as higher resolution and suitability for biological samples, it can be used as a universal technology for the quantitative analysis of other fluorine-containing pharmaceuticals and analytes.

Image overlay solution based on threshold detection for a compact near infrared fluorescence goggle system

NASA Astrophysics Data System (ADS)

Gao, Shengkui; Mondal, Suman B.; Zhu, Nan; Liang, RongGuang; Achilefu, Samuel; Gruev, Viktor

2015-01-01

Near infrared (NIR) fluorescence imaging has shown great potential for various clinical procedures, including intraoperative image guidance. However, existing NIR fluorescence imaging systems either have a large footprint or are handheld, which limits their usage in intraoperative applications. We present a compact NIR fluorescence imaging system (NFIS) with an image overlay solution based on threshold detection, which can be easily integrated with a goggle display system for intraoperative guidance. The proposed NFIS achieves compactness, light weight, hands-free operation, high-precision superimposition, and a real-time frame rate. In addition, the miniature and ultra-lightweight light-emitting diode tracking pod is easy to incorporate with NIR fluorescence imaging. Based on experimental evaluation, the proposed NFIS solution has a lower detection limit of 25 nM of indocyanine green at 27 fps and realizes a highly precise image overlay of NIR and visible images of mice in vivo. The overlay error is limited within a 2-mm scale at a 65-cm working distance, which is highly reliable for clinical study and surgical use.

Development and Validation of GC-ECD Method for the Determination of Metamitron in Soil

PubMed Central

Tandon, Shishir; Kumar, Satyendra; Sand, N. K.

2015-01-01

This paper aims at developing and validating a convenient, rapid, and sensitive method for estimation of metamitron from soil samples.Determination andquantification was carried out by Gas Chromatography on microcapillary column with an Electron Capture Detector source. The compound was extracted from soil using methanol and cleanup by C-18 SPE. After optimization, the method was validated by evaluating the analytical curves, linearity, limits of detection, and quantification, precision (repeatability and intermediate precision), and accuracy (recovery). Recovery values ranged from 89 to 93.5% within 0.05- 2.0 µg L−1 with average RSD 1.80%. The precision (repeatability) ranged from 1.7034 to 1.9144% and intermediate precision from 1.5685 to 2.1323%. Retention time was 6.3 minutes, and minimum detectable and quantifiable limits were 0.02 ng mL−1 and 0.05 ng g−1, respectively. Good linearity (R 2 = 0.998) of the calibration curves was obtained over the range from 0.05 to 2.0 µg L−1. Results indicated that the developed method is rapid and easy to perform, making it applicable for analysis in large pesticide monitoring programmes. PMID:25733978

A high-precision radial-velocity survey for other planetary systems

NASA Technical Reports Server (NTRS)

Cochran, William D.; Hatzes, Artie P.

1994-01-01

The precise measurement of variations in stellar radial velocities provides one of several promising methods of surveying a large sample of nearby solar type stars to detect planetary systems in orbit around them. The McDonald Observatory Planetary Search (MOPS) was started in 1987 September with the goal of detecting other nearby planetary systems. A stabilized I2 gas absorption cell placed in front of the entrance slit to the McDonald Observatory 2.7 m telescope coude spectrograph serves as the velocity metric. With this I2 cell we can achieve radial velocity measurement precision better than 10 m/s in an individual measurement. At this level we can detect a Jupiter-like planet around a solar-type star, and have some hope of detecting Saturn-like planets in a long-term survey. The detectability of planets is ultimately limited by stellar pulsation modes and photospheric motions. Monthly MOPS observing runs allow us to obtain at least 5 independent observations per year of the 33 solar-type (F5-K7) stars on our observing list. We present representative results from the first five years of the survey.

The elusive Heisenberg limit in quantum-enhanced metrology

PubMed Central

Demkowicz-Dobrzański, Rafał; Kołodyński, Jan; Guţă, Mădălin

2012-01-01

Quantum precision enhancement is of fundamental importance for the development of advanced metrological optical experiments, such as gravitational wave detection and frequency calibration with atomic clocks. Precision in these experiments is strongly limited by the 1/√N shot noise factor with N being the number of probes (photons, atoms) employed in the experiment. Quantum theory provides tools to overcome the bound by using entangled probes. In an idealized scenario this gives rise to the Heisenberg scaling of precision 1/N. Here we show that when decoherence is taken into account, the maximal possible quantum enhancement in the asymptotic limit of infinite N amounts generically to a constant factor rather than quadratic improvement. We provide efficient and intuitive tools for deriving the bounds based on the geometry of quantum channels and semi-definite programming. We apply these tools to derive bounds for models of decoherence relevant for metrological applications including: depolarization, dephasing, spontaneous emission and photon loss. PMID:22990859

Performance evaluation of the HepB Typer-Entecavir kit for detection of entecavir resistance mutations in chronic hepatitis B.

PubMed

Ahn, Sang Hoon; Chun, Ji-Yong; Shin, Soo-Kyung; Park, Jun Yong; Yoo, Wangdon; Hong, Sun Pyo; Kim, Soo-Ok; Han, Kwang-Hyub

2013-12-01

Molecular diagnostic methods have enabled the rapid diagnosis of drug-resistant mutations in hepatitis B virus (HBV) and have reduced both unnecessary therapeutic interventions and medical costs. In this study we evaluated the analytical and clinical performances of the HepB Typer-Entecavir kit (GeneMatrix, Korea) in detecting entecavir-resistance-associated mutations. The HepB Typer-Entecavir kit was evaluated for its limit of detection, interference, cross-reactivity, and precision using HBV reference standards made by diluting high-titer viral stocks in HBV-negative human serum. The performance of the HepB Typer-Entecavir kit for detecting mutations related to entecavir resistance was compared with direct sequencing for 396 clinical samples from 108 patients. Using the reference standards, the detection limit of the HepB Typer-Entecavir kit was found to be as low as 500 copies/mL. No cross-reactivity was observed, and elevated levels of various interfering substances did not adversely affect its analytical performance. The precision test conducted by repetitive analysis of 2,400 replicates with reference standards at various concentrations showed 99.9% agreement (2398/2400). The overall concordance rate between the HepB Typer-Entecavir kit and direct sequencing assays in 396 clinical samples was 99.5%. The HepB Typer-Entecavir kit showed high reliability and precision, and comparable sensitivity and specificity for detecting mutant virus populations in reference and clinical samples in comparison with direct sequencing. Therefore, this assay would be clinically useful in the diagnosis of entecavir-resistance-associated mutations in chronic hepatitis B.

Capacity and precision in an animal model of visual short-term memory

PubMed Central

Lara, Antonio H.; Wallis, Jonathan D.

2013-01-01

Temporary storage of information in visual short-term memory (VSTM) is a key component of many complex cognitive abilities. However, it is highly limited in capacity. Understanding the neurophysiological nature of this capacity limit will require a valid animal model of VSTM. We used a multiple-item color change detection task to measure macaque monkeys’ VSTM capacity. Subjects’ performance deteriorated and reaction times increased as a function of the number of items in memory. Additionally, we measured the precision of the memory representations by varying the distance between sample and test colors. In trials with similar sample and test colors, subjects made more errors compared to trials with highly discriminable colors. We modeled the error distribution as a Gaussian function and used this to estimate the precision of VSTM representations. We found that as the number of items in memory increases the precision of the representations decreases dramatically. Additionally, we found that focusing attention on one of the objects increases the precision with which that object is stored and degrading the precision of the remaining. These results are in line with recent findings in human psychophysics and provide a solid foundation for understanding the neurophysiological nature of the capacity limit of VSTM. PMID:22419756

Determination of rifampicin in human plasma by high-performance liquid chromatography coupled with ultraviolet detection after automatized solid-liquid extraction.

PubMed

Louveau, B; Fernandez, C; Zahr, N; Sauvageon-Martre, H; Maslanka, P; Faure, P; Mourah, S; Goldwirt, L

2016-12-01

A precise and accurate high-performance liquid chromatography (HPLC) quantification method of rifampicin in human plasma was developed and validated using ultraviolet detection after an automatized solid-phase extraction. The method was validated with respect to selectivity, extraction recovery, linearity, intra- and inter-day precision, accuracy, lower limit of quantification and stability. Chromatographic separation was performed on a Chromolith RP 8 column using a mixture of 0.05 m acetate buffer pH 5.7-acetonitrile (35:65, v/v) as mobile phase. The compounds were detected at a wavelength of 335 nm with a lower limit of quantification of 0.05 mg/L in human plasma. Retention times for rifampicin and 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline used as internal standard were respectively 3.77 and 4.81 min. This robust and exact method was successfully applied in routine for therapeutic drug monitoring in patients treated with rifampicin. Copyright © 2016 John Wiley & Sons, Ltd.

Rumsey and Walker_AMT_2016_Table 2.xlsx

EPA Pesticide Factsheets

Table summarizes instrument precision assessed by collocating the two sample boxes. Precision is quantified as the standard deviation of the residuals of an orthogonal least squares regression of concentrations from the two sample boxes. This allows for an estimation of gradient precision and ultimately gradient and flux detection limits. This dataset is associated with the following publication:Rumsey, I. Application of an online ion chromatography-based instrument for gradient flux measurements of speciated nitrogen and sulfur. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 9(6): 2581-2592, (2016).

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

USGS Publications Warehouse

McLain, B.J.

1993-01-01

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

Verification of spectrophotometric method for nitrate analysis in water samples

NASA Astrophysics Data System (ADS)

Kurniawati, Puji; Gusrianti, Reny; Dwisiwi, Bledug Bernanti; Purbaningtias, Tri Esti; Wiyantoko, Bayu

2017-12-01

The aim of this research was to verify the spectrophotometric method to analyze nitrate in water samples using APHA 2012 Section 4500 NO3-B method. The verification parameters used were: linearity, method detection limit, level of quantitation, level of linearity, accuracy and precision. Linearity was obtained by using 0 to 50 mg/L nitrate standard solution and the correlation coefficient of standard calibration linear regression equation was 0.9981. The method detection limit (MDL) was defined as 0,1294 mg/L and limit of quantitation (LOQ) was 0,4117 mg/L. The result of a level of linearity (LOL) was 50 mg/L and nitrate concentration 10 to 50 mg/L was linear with a level of confidence was 99%. The accuracy was determined through recovery value was 109.1907%. The precision value was observed using % relative standard deviation (%RSD) from repeatability and its result was 1.0886%. The tested performance criteria showed that the methodology was verified under the laboratory conditions.

Digital PCR methods improve detection sensitivity and measurement precision of low abundance mtDNA deletions.

PubMed

Belmonte, Frances R; Martin, James L; Frescura, Kristin; Damas, Joana; Pereira, Filipe; Tarnopolsky, Mark A; Kaufman, Brett A

2016-04-28

Mitochondrial DNA (mtDNA) mutations are a common cause of primary mitochondrial disorders, and have also been implicated in a broad collection of conditions, including aging, neurodegeneration, and cancer. Prevalent among these pathogenic variants are mtDNA deletions, which show a strong bias for the loss of sequence in the major arc between, but not including, the heavy and light strand origins of replication. Because individual mtDNA deletions can accumulate focally, occur with multiple mixed breakpoints, and in the presence of normal mtDNA sequences, methods that detect broad-spectrum mutations with enhanced sensitivity and limited costs have both research and clinical applications. In this study, we evaluated semi-quantitative and digital PCR-based methods of mtDNA deletion detection using double-stranded reference templates or biological samples. Our aim was to describe key experimental assay parameters that will enable the analysis of low levels or small differences in mtDNA deletion load during disease progression, with limited false-positive detection. We determined that the digital PCR method significantly improved mtDNA deletion detection sensitivity through absolute quantitation, improved precision and reduced assay standard error.

Digital PCR methods improve detection sensitivity and measurement precision of low abundance mtDNA deletions

PubMed Central

Belmonte, Frances R.; Martin, James L.; Frescura, Kristin; Damas, Joana; Pereira, Filipe; Tarnopolsky, Mark A.; Kaufman, Brett A.

2016-01-01

Mitochondrial DNA (mtDNA) mutations are a common cause of primary mitochondrial disorders, and have also been implicated in a broad collection of conditions, including aging, neurodegeneration, and cancer. Prevalent among these pathogenic variants are mtDNA deletions, which show a strong bias for the loss of sequence in the major arc between, but not including, the heavy and light strand origins of replication. Because individual mtDNA deletions can accumulate focally, occur with multiple mixed breakpoints, and in the presence of normal mtDNA sequences, methods that detect broad-spectrum mutations with enhanced sensitivity and limited costs have both research and clinical applications. In this study, we evaluated semi-quantitative and digital PCR-based methods of mtDNA deletion detection using double-stranded reference templates or biological samples. Our aim was to describe key experimental assay parameters that will enable the analysis of low levels or small differences in mtDNA deletion load during disease progression, with limited false-positive detection. We determined that the digital PCR method significantly improved mtDNA deletion detection sensitivity through absolute quantitation, improved precision and reduced assay standard error. PMID:27122135

An overview of LIGO and Virgo -- status and plans

NASA Astrophysics Data System (ADS)

Miller, John

2014-06-01

Interferometric gravitational-wave detectors, the most sensitive position meters ever operated, aim to detect the motion of massive bodies throughout the universe by pushing precision measurement to the standard quantum limit and beyond. A global network of these detectors is currently under construction, promising unprecedented sensitivity and the ability to determine the sky position of any detected signals. I will describe the current status and expected performance of this network with a focus on limiting noise sources and the techniques currently being developed to combat them.

Background-Free 3D Nanometric Localization and Sub-nm Asymmetry Detection of Single Plasmonic Nanoparticles by Four-Wave Mixing Interferometry with Optical Vortices

NASA Astrophysics Data System (ADS)

Zoriniants, George; Masia, Francesco; Giannakopoulou, Naya; Langbein, Wolfgang; Borri, Paola

2017-10-01

Single nanoparticle tracking using optical microscopy is a powerful technique with many applications in biology, chemistry, and material sciences. Despite significant advances, localizing objects with nanometric position precision in a scattering environment remains challenging. Applied methods to achieve contrast are dominantly fluorescence based, with fundamental limits in the emitted photon fluxes arising from the excited-state lifetime as well as photobleaching. Here, we show a new four-wave-mixing interferometry technique, whereby the position of a single nonfluorescing gold nanoparticle of 25-nm radius is determined with 16 nm precision in plane and 3 nm axially from rapid single-point measurements at 1-ms acquisition time by exploiting optical vortices. The precision in plane is consistent with the photon shot-noise, while axially it is limited by the nano-positioning sample stage, with an estimated photon shot-noise limit of 0.5 nm. The detection is background-free even inside biological cells. The technique is also uniquely sensitive to particle asymmetries of only 0.5% ellipticity, corresponding to a single atomic layer of gold, as well as particle orientation. This method opens new ways of unraveling single-particle trafficking within complex 3D architectures.

Measurement of atmospheric ozone by cavity ring-down spectroscopy.

PubMed

Washenfelder, R A; Wagner, N L; Dube, W P; Brown, S S

2011-04-01

Ozone plays a key role in both the Earth's radiative budget and photochemistry. Accurate, robust analytical techniques for measuring its atmospheric abundance are of critical importance. Cavity ring-down spectroscopy has been successfully used for sensitive and accurate measurements of many atmospheric species. However, this technique has not been used for atmospheric measurements of ozone, because the strongest ozone absorption bands occur in the ultraviolet spectral region, where Rayleigh and Mie scattering cause significant cavity losses and dielectric mirror reflectivities are limited. Here, we describe a compact instrument that measures O3 by chemical conversion to NO2 in excess NO, with subsequent detection by cavity ring-down spectroscopy. This method provides a simple, accurate, and high-precision measurement of atmospheric ozone. The instrument consists of two channels. The sum of NO2 and converted O3 (defined as Ox) is measured in the first channel, while NO2 alone is measured in the second channel. NO2 is directly detected in each channel by cavity ring-down spectroscopy with a laser diode light source at 404 nm. The limit of detection for O3 is 26 pptv (2 sigma precision) at 1 s time resolution. The accuracy of the measurement is ±2.2%, with the largest uncertainty being the effective NO2 absorption cross-section. The linear dynamic range of the instrument has been verified from the detection limit to above 200 ppbv (r2>99.99%). The observed precision on signal (2 sigma) with 41 ppbv O3 is 130 pptv in 1 s. Comparison of this instrument to UV absorbance instruments for ambient O3 concentrations shows linear agreement (r2=99.1%) with slope of 1.012±0.002.

Development and validation of an automated and marker-free CT-based spatial analysis method (CTSA) for assessment of femoral hip implant migration: In vitro accuracy and precision comparable to that of radiostereometric analysis (RSA).

PubMed

Scheerlinck, Thierry; Polfliet, Mathias; Deklerck, Rudi; Van Gompel, Gert; Buls, Nico; Vandemeulebroucke, Jef

2016-01-01

We developed a marker-free automated CT-based spatial analysis (CTSA) method to detect stem-bone migration in consecutive CT datasets and assessed the accuracy and precision in vitro. Our aim was to demonstrate that in vitro accuracy and precision of CTSA is comparable to that of radiostereometric analysis (RSA). Stem and bone were segmented in 2 CT datasets and both were registered pairwise. The resulting rigid transformations were compared and transferred to an anatomically sound coordinate system, taking the stem as reference. This resulted in 3 translation parameters and 3 rotation parameters describing the relative amount of stem-bone displacement, and it allowed calculation of the point of maximal stem migration. Accuracy was evaluated in 39 comparisons by imposing known stem migration on a stem-bone model. Precision was estimated in 20 comparisons based on a zero-migration model, and in 5 patients without stem loosening. Limits of the 95% tolerance intervals (TIs) for accuracy did not exceed 0.28 mm for translations and 0.20° for rotations (largest standard deviation of the signed error (SD(SE)): 0.081 mm and 0.057°). In vitro, limits of the 95% TI for precision in a clinically relevant setting (8 comparisons) were below 0.09 mm and 0.14° (largest SD(SE): 0.012 mm and 0.020°). In patients, the precision was lower, but acceptable, and dependent on CT scan resolution. CTSA allows detection of stem-bone migration with an accuracy and precision comparable to that of RSA. It could be valuable for evaluation of subtle stem loosening in clinical practice.

Digital photo monitoring for tree crown

Treesearch

Neil Clark; Sang-Mook Lee

2007-01-01

Assessing change in the amount of foliage within a tree’s crown is the goal of crown transparency estimation, a component in many forest health assessment programs. Many sources of variability limit analysis and interpretation of crown condition data. Increased precision is needed to detect more subtle changes that are important for detection of health problems....

Guidelines to indirectly measure and enhance detection efficiency of stationary PIT tag interrogation systems in streams

USGS Publications Warehouse

Connolly, Patrick J.; Wolf, Keith; O'Neal, Jennifer S.

2010-01-01

With increasing use of passive integrated transponder (PIT) tags and reliance on stationary PIT tag interrogation systems to monitor fish populations, guidelines are offered to inform users how best to use limited funding and human resources to create functional systems that maximize a desired level of detection and precision. The estimators of detection efficiency and their variability as described by Connolly et al. (2008) are explored over a span of likely performance metrics. These estimators were developed to estimate detection efficiency without relying on a known number of fish passing the system. I present graphical displays of the results derived from these estimators to show the potential efficiency and precision to be gained by adding an array or by increasing the number of PIT-tagged fish expected to move past an interrogation system.

Guidelines for calculating and enhancing detection efficiency of PIT tag interrogation systems

USGS Publications Warehouse

Connolly, Patrick J.

2010-01-01

With increasing use of passive integrated transponder (PIT) tags and reliance on stationary PIT tag interrogation systems to monitor fish populations, guidelines are offered to inform users how best to use limited funding and human resources to create functional systems that maximize a desired level of detection and precision. The estimators of detection efficiency and their variability as described by Connolly et al. (2008) are explored over a span of likely performance metrics. These estimators were developed to estimate detection efficiency without relying on a known number of fish passing the system. I present graphical displays of the results derived from these estimators to show the potential efficiency and precision to be gained by adding an array or by increasing the number of PIT-tagged fish expected to move past an interrogation system.

Performance evaluation of the HepB Typer-Entecavir kit for detection of entecavir resistance mutations in chronic hepatitis B

PubMed Central

Ahn, Sang Hoon; Chun, Ji-Yong; Shin, Soo-Kyung; Park, Jun Yong; Yoo, Wangdon; Hong, Sun Pyo; Han, Kwang-Hyub

2013-01-01

Background/Aims Molecular diagnostic methods have enabled the rapid diagnosis of drug-resistant mutations in hepatitis B virus (HBV) and have reduced both unnecessary therapeutic interventions and medical costs. In this study we evaluated the analytical and clinical performances of the HepB Typer-Entecavir kit (GeneMatrix, Korea) in detecting entecavir-resistance-associated mutations. Methods The HepB Typer-Entecavir kit was evaluated for its limit of detection, interference, cross-reactivity, and precision using HBV reference standards made by diluting high-titer viral stocks in HBV-negative human serum. The performance of the HepB Typer-Entecavir kit for detecting mutations related to entecavir resistance was compared with direct sequencing for 396 clinical samples from 108 patients. Results Using the reference standards, the detection limit of the HepB Typer-Entecavir kit was found to be as low as 500 copies/mL. No cross-reactivity was observed, and elevated levels of various interfering substances did not adversely affect its analytical performance. The precision test conducted by repetitive analysis of 2,400 replicates with reference standards at various concentrations showed 99.9% agreement (2398/2400). The overall concordance rate between the HepB Typer-Entecavir kit and direct sequencing assays in 396 clinical samples was 99.5%. Conclusions The HepB Typer-Entecavir kit showed high reliability and precision, and comparable sensitivity and specificity for detecting mutant virus populations in reference and clinical samples in comparison with direct sequencing. Therefore, this assay would be clinically useful in the diagnosis of entecavir-resistance-associated mutations in chronic hepatitis B. PMID:24459645

[Determination of vitamins D2, vitamin D3 in cosmetics by high performance liquid chromatography].

PubMed

Zhu, Ying; Yang, Yan-Wei; Wang, Xin

2005-09-01

A high performance liquid chromatography method was used to detect vitamins D2 and vitamin D3, which is useful to know the use of vitamins D2 and vitamin D3 in cosmetics, prohibit the influx of cosmetics containing vitamins D2 and vitamin D3 to cosmetic market, safeguard the health of consumers. A high performance liquid chromatography method was established for determination of vitamins D2 and vitamin D3 in cosmetics. The separation condition was optimized by trying different type of columns and mobile phases. The experiment goes on a Alltima C18 column (250 mm x 4.6 mm I. D., 5 microm)using methanol-acetonitrile (90: 10) as mobile phase at a flow rate of 1.0 ml/min, with the column temperature 25 degrees C and detection wave 265nm. The liner range is from 0.5 mg/L to 100 mg/L with good relationship. The detection limit of vitamin D2 is 0. 12 mg/L, the precision is less than 3.8% and recovery varies from 94.2% to 101.4%, while the detection limit of vitamin D3 is 0.06 mg/L, the precision is less than 3.5% and recovery varies from 91.6% to 97.2%. The method is simple, precise and accurate, which is suitable for the determination of vitamins D2 and vitamin D3 in cosmetics.

Extension of Fong and Alvarez: When is a lower limit of detection low enough

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

Potter, W.E.

1999-11-01

The work of Fong and Alvarez is easily extended for counting when varied counting is not employed. It remains true in the general case that the precision of a counting method can be no less than about 30% at the LLD and so it is desirable to have decision levels at least several times larger than the LLD so that measurements have sufficient precision to make valid decisions.

Extension of Fong and Alvarez: When is a lower limit of detection low enough?

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

Potter, W.E.

1999-11-01

The work of Fong and Alvarez is easily extended for counting when varied counting is not employed. It remains true in the general case that the precision of a counting method can be no less than about 30% at the LLD and so it is desirable to have decision levels at least several times larger than the LLD so that measurements have sufficient precision to make valid decisions.

Exposure to 4,4'-methylenediphenyl diisocyanate (MDI) during moulding of rigid polyurethane foam: determination of airborne MDI and urinary 4,4'-methylenedianiline (MDA).

PubMed

Kääriä, K; Hirvonen, A; Norppa, H; Piirilä, P; Vainio, H; Rosenberg, C

2001-04-01

Occupational exposure to 4,4'-methylenediphenyl diisocyanate (MDI) was measured during moulding of rigid polyurethane foam. The aim of the study was to find out whether an MDI-derived urinary amine metabolite could be detected in the urine of workers exposed to apparently low levels of MDI. Airborne MDI was sampled on 1-(2-methoxyphenyl)-piperazine (2MP)-impregnated glass fibre filters and determined by high-performance liquid chromatography (HPLC) using ultraviolet (UV) and electrochemical (EC) detection. The limit of detection of MDI was 3 ng ml-1 for a 20 microliters injection. The precision of sample preparation, expressed as relative standard deviation (RSD), was 1.3% with UV detection and 2.1% with EC detection at a concentration of 70 ng MDI ml-1 (n = 6). The 2MP-MDI derivative was stable at +4 degrees C up to eight weeks. The accuracy of the method was validated in an international quality control programme. Workers (n = 57) from three different factories participated in the study. Urinary 4,4'-methylenedianiline (MDA) metabolite was determined after acid hydrolysis as heptafluorobutyric anhydride derivatives by gas chromatography-mass spectrometry using chemical ionisation and monitoring negative ions. The limit of detection in urine was 0.2 nmol l-1. The precision of six analyses for a urine sample spiked to a concentration of 1 nmol l-1 was 29% (RSD). The MDI concentrations were below the limit of detection in most (64%) of the air samples collected in the worker's breathing zone. Still, detectable amounts of MDA were found in 97% of the urine samples. Monitoring of urinary MDA appears to be an appropriate method of assessing MDI exposure in work environments with low or undetectable MDI concentrations in the workplace air.

AW UMa observed with MOST satellite

NASA Astrophysics Data System (ADS)

Rucinski, S. M.; Matthews, J. M.; Cameron, C.; Guenther, D. B.; Kuschnig, R.; Moffat, A. F. J.; Rowe, J. F.; Sasselov, D.; Weiss, W. W.

2013-11-01

MOST observations were obtained to search for photometric non-radial oscillations; none was detected with an upper limit of 0.0001 in relative amplitude. A single, precise moment of the primary eclipse confirms the progressive shortening of the orbital period.

Assessing the detectability of antioxidants in two-dimensional high-performance liquid chromatography.

PubMed

Bassanese, Danielle N; Conlan, Xavier A; Barnett, Neil W; Stevenson, Paul G

2015-05-01

This paper explores the analytical figures of merit of two-dimensional high-performance liquid chromatography for the separation of antioxidant standards. The cumulative two-dimensional high-performance liquid chromatography peak area was calculated for 11 antioxidants by two different methods--the areas reported by the control software and by fitting the data with a Gaussian model; these methods were evaluated for precision and sensitivity. Both methods demonstrated excellent precision in regards to retention time in the second dimension (%RSD below 1.16%) and cumulative second dimension peak area (%RSD below 3.73% from the instrument software and 5.87% for the Gaussian method). Combining areas reported by the high-performance liquid chromatographic control software displayed superior limits of detection, in the order of 1 × 10(-6) M, almost an order of magnitude lower than the Gaussian method for some analytes. The introduction of the countergradient eliminated the strong solvent mismatch between dimensions, leading to a much improved peak shape and better detection limits for quantification. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Circulating tumor DNA as a liquid biopsy target for detection of pancreatic cancer

PubMed Central

Takai, Erina; Yachida, Shinichi

2016-01-01

Most pancreatic cancer patients present with advanced metastatic disease, resulting in extremely poor 5-year survival, mainly because of the lack of a reliable modality for early detection and limited therapeutic options for advanced disease. Therefore, there is a need for minimally-invasive diagnostic tools for detecting pancreatic cancer at an early stage, when curative surgery and also novel therapeutic approaches including precision medicine may be feasible. The “liquid biopsy” addresses these unmet clinical needs based on the concept that simple peripheral blood sampling and detection of circulating tumor DNA (ctDNA) could provide diagnostic information. In this review, we provide an overview of the current status of blood-based tests for diagnosis of pancreatic cancer and the potential utility of ctDNA for precision medicine. We also discuss challenges that remain to be addressed in developing practical ctDNA-based liquid biopsy approaches for early diagnosis of pancreatic cancer. PMID:27784960

Circulating tumor DNA as a liquid biopsy target for detection of pancreatic cancer.

PubMed

Takai, Erina; Yachida, Shinichi

2016-10-14

Most pancreatic cancer patients present with advanced metastatic disease, resulting in extremely poor 5-year survival, mainly because of the lack of a reliable modality for early detection and limited therapeutic options for advanced disease. Therefore, there is a need for minimally-invasive diagnostic tools for detecting pancreatic cancer at an early stage, when curative surgery and also novel therapeutic approaches including precision medicine may be feasible. The "liquid biopsy" addresses these unmet clinical needs based on the concept that simple peripheral blood sampling and detection of circulating tumor DNA (ctDNA) could provide diagnostic information. In this review, we provide an overview of the current status of blood-based tests for diagnosis of pancreatic cancer and the potential utility of ctDNA for precision medicine. We also discuss challenges that remain to be addressed in developing practical ctDNA-based liquid biopsy approaches for early diagnosis of pancreatic cancer.

Sample Introduction Using the Hildebrand Grid Nebulizer for Plasma Spectrometry

DTIC Science & Technology

1988-01-01

linear dynamic ranges, precision, and peak width were de- termined for elements in methanol and acetonitrile solutions. , (1)> The grid nebulizer was...FIA) with ICP-OES detection were evaluated. Detec- tion limits, linear dynamic ranges, precision, and peak width were de- termined for elements in...Concentration vs. Log Peak Area for Mn, 59 Cd, Zn, Au, Ni in Methanol (CMSC) 3-28 Log Concentration vs. Log Peak Area for Mn, 60 Cd, Au, Ni in

Validation of an analytical method for simultaneous high-precision measurements of greenhouse gas emissions from wastewater treatment plants using a gas chromatography-barrier discharge detector system.

PubMed

Pascale, Raffaella; Caivano, Marianna; Buchicchio, Alessandro; Mancini, Ignazio M; Bianco, Giuliana; Caniani, Donatella

2017-01-13

Wastewater treatment plants (WWTPs) emit CO 2 and N 2 O, which may lead to climate change and global warming. Over the last few years, awareness of greenhouse gas (GHG) emissions from WWTPs has increased. Moreover, the development of valid, reliable, and high-throughput analytical methods for simultaneous gas analysis is an essential requirement for environmental applications. In the present study, an analytical method based on a gas chromatograph (GC) equipped with a barrier ionization discharge (BID) detector was developed for the first time. This new method simultaneously analyses CO 2 and N 2 O and has a precision, measured in terms of relative standard of variation RSD%, equal to or less than 6.6% and 5.1%, respectively. The method's detection limits are 5.3ppm v for CO 2 and 62.0ppb v for N 2 O. The method's selectivity, linearity, accuracy, repeatability, intermediate precision, limit of detection and limit of quantification were good at trace concentration levels. After validation, the method was applied to a real case of N 2 O and CO 2 emissions from a WWTP, confirming its suitability as a standard procedure for simultaneous GHG analysis in environmental samples containing CO 2 levels less than 12,000mg/L. Copyright © 2016 Elsevier B.V. All rights reserved.

SAMPLING AND ANALYSIS OF MERCURY IN CRUDE OIL

EPA Science Inventory

Sampling and analytical procedures used to determine total mercury content in crude oils were examined. Three analytical methods were compared with respect to accuracy, precision and detection limit. The combustion method and a commercial extraction method were found adequate to...

Simultaneous determination of seven multiclass veterinary antibiotics in surface water samples in the Republic of Korea using liquid chromatography with tandem mass spectrometry.

PubMed

Chung, Hyung Suk; Choi, Jeong-Heui; Abd El-Aty, A M; Lee, Young-Jun; Lee, Han Sol; Kim, Sangdon; Jung, Hee-Jung; Kang, Tae-Woo; Shin, Ho-Chul; Shim, Jae-Han

2016-12-01

A simultaneous determination method using solid-phase extraction and liquid chromatography with tandem mass spectrometry was developed to detect and quantify the presence of seven multiclass veterinary antibiotics (13 compounds in total) in surface water samples, which included the effluents of livestock wastewater and sewage treatment plants, as well as the reservoir drainage areas from dense animal farms. The pH of all water samples was adjusted to 2 or 6 before solid-phase extraction using Oasis HLB cartridges. The developed method was fully validated in terms of linearity, method detection limit, method quantitation limit, accuracy, and precision. The linearity of all tested drugs was good, with R 2 determination coefficients ≥ 0.9931. The method detection limits and method quantitation limits were 0.1-74.3 and 0.5-236.6 ng/L, respectively. Accuracy and precision values were 71-120 and 1-17%, respectively. The determination method was successfully applied for monitoring water samples obtained from the Yeongsan River in 2015. The most frequently detected antibiotics were lincomycin (96%), sulfamethazine (90%), sulfamethoxazole (88%), and sulfathiazole (50%); the maximum concentrations of which were 398.9, 1151.3, 533.1, and 307.4 ng/L, respectively. Overall, the greatest numbers and concentrations of detected antibiotics were found in samples from the effluents of livestock wastewater, sewage treatment plants, and reservoir drainage areas. Diverse veterinary antibiotics were present, and their presence was dependent upon the commercial sales and environmental properties of the analytes, the geographical positions of the sampling points, and the origin of the water. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of quinolones and fluoroquinolones, tetracyclines and sulfonamides in bovine, swine and poultry liver using LC-MS/MS.

PubMed

Martins, Magda Targa; Barreto, Fabiano; Hoff, Rodrigo Barcelos; Jank, Louise; Arsand, Juliana Bazzan; Feijó, Tiago Correa; Schapoval, Elfrides Eva Scherman

2015-01-01

Antibacterials are widely used in veterinary medicine. Residues of these drugs can remain in food of animal origin, including bovine liver. This paper describes a fast and simple analytical method for the determination of quinolones and fluoroquinolones, tetracyclines and sulfonamides in bovine liver samples. Deuterated enrofloxacin, sulfapyridine and demeclocycline were used as internal standards. The homogenised liver samples were extracted with acidified acetonitrile. Steps of non-solid-phase extraction (SPE) clean-up and concentration were used in the presented method. The final extracts were analysed by sensitive and selective detection of all components in a single run using LC-MS/MS. Acceptable recoveries between 66% and 110% were obtained. Good linearity (r(2)) above 0.96, considering three different days, for all drugs was achieved in concentrations ranging from 0.0 to 2.0 × the maximum residue limit (MRL). Intraday precision with coefficient of variation (CV%) (n = 6) lower than 14.7% and inter-day precision lower than 18.8% in agreement with European Commission Decision 2002/657/EC were obtained in concentrations ranging from 0.5 to 1.5 MRL. Accuracy was between 86% and 110%. Limits of detection and quantitation, as well as decision limit (CCα) and detection capability (CCβ), were also evaluated.

Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Rudd, Van; Shald, Scott; Sandford, Stephen; Dimarcantonio, Albert

2014-01-01

In this paper, the development of a long range ladar system known as ExoSPEAR at NASA Langley Research Center for tracking rapidly moving resident space objects is discussed. Based on 100 W, nanosecond class, near-IR laser, this ladar system with coherent detection technique is currently being investigated for short dwell time measurements of resident space objects (RSOs) in LEO and beyond for space surveillance applications. This unique ladar architecture is configured using a continuously agile doublet-pulse waveform scheme coupled to a closed-loop tracking and control loop approach to simultaneously achieve mm class range precision and mm/s velocity precision and hence obtain unprecedented track accuracies. Salient features of the design architecture followed by performance modeling and engagement simulations illustrating the dependence of range and velocity precision in LEO orbits on ladar parameters are presented. Estimated limits on detectable optical cross sections of RSOs in LEO orbits are discussed.

Maximizing the Biochemical Resolving Power of Fluorescence Microscopy

PubMed Central

Esposito, Alessandro; Popleteeva, Marina; Venkitaraman, Ashok R.

2013-01-01

Most recent advances in fluorescence microscopy have focused on achieving spatial resolutions below the diffraction limit. However, the inherent capability of fluorescence microscopy to non-invasively resolve different biochemical or physical environments in biological samples has not yet been formally described, because an adequate and general theoretical framework is lacking. Here, we develop a mathematical characterization of the biochemical resolution in fluorescence detection with Fisher information analysis. To improve the precision and the resolution of quantitative imaging methods, we demonstrate strategies for the optimization of fluorescence lifetime, fluorescence anisotropy and hyperspectral detection, as well as different multi-dimensional techniques. We describe optimized imaging protocols, provide optimization algorithms and describe precision and resolving power in biochemical imaging thanks to the analysis of the general properties of Fisher information in fluorescence detection. These strategies enable the optimal use of the information content available within the limited photon-budget typically available in fluorescence microscopy. This theoretical foundation leads to a generalized strategy for the optimization of multi-dimensional optical detection, and demonstrates how the parallel detection of all properties of fluorescence can maximize the biochemical resolving power of fluorescence microscopy, an approach we term Hyper Dimensional Imaging Microscopy (HDIM). Our work provides a theoretical framework for the description of the biochemical resolution in fluorescence microscopy, irrespective of spatial resolution, and for the development of a new class of microscopes that exploit multi-parametric detection systems. PMID:24204821

A Self Contained Method for Safe and Precise Lunar Landing

NASA Technical Reports Server (NTRS)

Paschall, Stephen C., II; Brady, Tye; Cohanim, Babak; Sostaric, Ronald

2008-01-01

The return of humans to the Moon will require increased capability beyond that of the previous Apollo missions. Longer stay times and a greater flexibility with regards to landing locations are among the many improvements planned. A descent and landing system that can land the vehicle more accurately than Apollo with a greater ability to detect and avoid hazards is essential to the development of a Lunar Outpost, and also for increasing the number of potentially reachable Lunar Sortie locations. This descent and landing system should allow landings in more challenging terrain and provide more flexibility with regards to mission timing and lighting considerations, while maintaining safety as the top priority. The lunar landing system under development by the ALHAT (Autonomous precision Landing and Hazard detection Avoidance Technology) project is addressing this by providing terrain-relative navigation measurements to enhance global-scale precision, an onboard hazard-detection system to select safe landing locations, and an Autonomous GNC (Guidance, Navigation, and Control) capability to process these measurements and safely direct the vehicle to this landing location. This ALHAT landing system will enable safe and precise lunar landings without requiring lunar infrastructure in the form of navigation aids or a priori identified hazard-free landing locations. The safe landing capability provided by ALHAT uses onboard active sensing to detect hazards that are large enough to be a danger to the vehicle but too small to be detected from orbit, given currently planned orbital terrain resolution limits. Algorithms to interpret raw active sensor terrain data and generate hazard maps as well as identify safe sites and recalculate new trajectories to those sites are included as part of the ALHAT System. These improvements to descent and landing will help contribute to repeated safe and precise landings for a wide variety of terrain on the Moon.

Clinical proteomics-driven precision medicine for targeted cancer therapy: current overview and future perspectives.

PubMed

Zhou, Li; Wang, Kui; Li, Qifu; Nice, Edouard C; Zhang, Haiyuan; Huang, Canhua

2016-01-01

Cancer is a common disease that is a leading cause of death worldwide. Currently, early detection and novel therapeutic strategies are urgently needed for more effective management of cancer. Importantly, protein profiling using clinical proteomic strategies, with spectacular sensitivity and precision, offer excellent promise for the identification of potential biomarkers that would direct the development of targeted therapeutic anticancer drugs for precision medicine. In particular, clinical sample sources, including tumor tissues and body fluids (blood, feces, urine and saliva), have been widely investigated using modern high-throughput mass spectrometry-based proteomic approaches combined with bioinformatic analysis, to pursue the possibilities of precision medicine for targeted cancer therapy. Discussed in this review are the current advantages and limitations of clinical proteomics, the available strategies of clinical proteomics for the management of precision medicine, as well as the challenges and future perspectives of clinical proteomics-driven precision medicine for targeted cancer therapy.

The NASA Meter Class Autonomous Telescope: Ascension Island

DTIC Science & Technology

2013-09-01

understand the debris environment by providing high fidelity data in a timely manner to protect satellites and spacecraft in orbit around the Earth...gigabytes of image data nightly. With fainter detection limits, precision detection, acquisition and tracking of targets, multi-color photometry ...ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for

Simultaneous Determination of Potassium Clavulanate and Amoxicillin Trihydrate in Bulk, Pharmaceutical Formulations and in Human Urine Samples by UV Spectrophotometry

PubMed Central

Gujral, Rajinder Singh; Haque, Sk Manirul

2010-01-01

A simple and sensitive UV spectrophotometric method was developed and validated for the simultaneous determination of Potassium Clavulanate (PC) and Amoxicillin Trihydrate (AT) in bulk, pharmaceutical formulations and in human urine samples. The method was linear in the range of 0.2–8.5 μg/ml for PC and 6.4–33.6 μg/ml for AT. The absorbance was measured at 205 and 271 nm for PC and AT respectively. The method was validated with respect to accuracy, precision, specificity, ruggedness, robustness, limit of detection and limit of quantitation. This method was used successfully for the quality assessment of four PC and AT drug products and in human urine samples with good precision and accuracy. This is found to be simple, specific, precise, accurate, reproducible and low cost UV Spectrophotometric method. PMID:23675211

Convection in Cool Stars, as Seen Through Kepler's Eyes

NASA Astrophysics Data System (ADS)

Bastien, Fabienne A.

2015-01-01

Stellar surface processes represent a fundamental limit to the detection of extrasolar planets with the currently most heavily-used techniques. As such, considerable effort has gone into trying to mitigate the impact of these processes on planet detection, with most studies focusing on magnetic spots. Meanwhile, high-precision photometric planet surveys like CoRoT and Kepler have unveiled a wide variety of stellar variability at previously inaccessible levels. We demonstrate that these newly revealed variations are not solely magnetically driven but also trace surface convection through light curve ``flicker.'' We show that ``flicker'' not only yields a simple measurement of surface gravity with a precision of ˜0.1 dex, but it may also improve our knowledge of planet properties, enhance radial velocity planet detection and discovery, and provide new insights into stellar evolution.

Quantization and training of object detection networks with low-precision weights and activations

NASA Astrophysics Data System (ADS)

Yang, Bo; Liu, Jian; Zhou, Li; Wang, Yun; Chen, Jie

2018-01-01

As convolutional neural networks have demonstrated state-of-the-art performance in object recognition and detection, there is a growing need for deploying these systems on resource-constrained mobile platforms. However, the computational burden and energy consumption of inference for these networks are significantly higher than what most low-power devices can afford. To address these limitations, this paper proposes a method to train object detection networks with low-precision weights and activations. The probability density functions of weights and activations of each layer are first directly estimated using piecewise Gaussian models. Then, the optimal quantization intervals and step sizes for each convolution layer are adaptively determined according to the distribution of weights and activations. As the most computationally expensive convolutions can be replaced by effective fixed point operations, the proposed method can drastically reduce computation complexity and memory footprint. Performing on the tiny you only look once (YOLO) and YOLO architectures, the proposed method achieves comparable accuracy to their 32-bit counterparts. As an illustration, the proposed 4-bit and 8-bit quantized versions of the YOLO model achieve a mean average precision of 62.6% and 63.9%, respectively, on the Pascal visual object classes 2012 test dataset. The mAP of the 32-bit full-precision baseline model is 64.0%.

A Miniaturized Colorimeter with a Novel Design and High Precision for Photometric Detection.

PubMed

Yan, Jun-Chao; Chen, Yan; Pang, Yu; Slavik, Jan; Zhao, Yun-Fei; Wu, Xiao-Ming; Yang, Yi; Yang, Si-Fan; Ren, Tian-Ling

2018-03-08

Water quality detection plays an increasingly important role in environmental protection. In this work, a novel colorimeter based on the Beer-Lambert law was designed for chemical element detection in water with high precision and miniaturized structure. As an example, the colorimeter can detect phosphorus, which was accomplished in this article to evaluate the performance. Simultaneously, a modified algorithm was applied to extend the linear measurable range. The colorimeter encompassed a near infrared laser source, a microflow cell based on microfluidic technology and a light-sensitive detector, then Micro-Electro-Mechanical System (MEMS) processing technology was used to form a stable integrated structure. Experiments were performed based on the ammonium molybdate spectrophotometric method, including the preparation of phosphorus standard solution, reducing agent, chromogenic agent and color reaction. The device can obtain a wide linear response range (0.05 mg/L up to 7.60 mg/L), a wide reliable measuring range up to 10.16 mg/L after using a novel algorithm, and a low limit of detection (0.02 mg/L). The size of flow cell in this design is 18 mm × 2.0 mm × 800 μm, obtaining a low reagent consumption of 0.004 mg ascorbic acid and 0.011 mg ammonium molybdate per determination. Achieving these advantages of miniaturized volume, high precision and low cost, the design can also be used in automated in situ detection.

A Miniaturized Colorimeter with a Novel Design and High Precision for Photometric Detection

PubMed Central

Chen, Yan; Pang, Yu; Slavik, Jan; Zhao, Yun-Fei; Wu, Xiao-Ming; Yang, Yi; Yang, Si-Fan; Ren, Tian-Ling

2018-01-01

Water quality detection plays an increasingly important role in environmental protection. In this work, a novel colorimeter based on the Beer-Lambert law was designed for chemical element detection in water with high precision and miniaturized structure. As an example, the colorimeter can detect phosphorus, which was accomplished in this article to evaluate the performance. Simultaneously, a modified algorithm was applied to extend the linear measurable range. The colorimeter encompassed a near infrared laser source, a microflow cell based on microfluidic technology and a light-sensitive detector, then Micro-Electro-Mechanical System (MEMS) processing technology was used to form a stable integrated structure. Experiments were performed based on the ammonium molybdate spectrophotometric method, including the preparation of phosphorus standard solution, reducing agent, chromogenic agent and color reaction. The device can obtain a wide linear response range (0.05 mg/L up to 7.60 mg/L), a wide reliable measuring range up to 10.16 mg/L after using a novel algorithm, and a low limit of detection (0.02 mg/L). The size of flow cell in this design is 18 mm × 2.0 mm × 800 μm, obtaining a low reagent consumption of 0.004 mg ascorbic acid and 0.011 mg ammonium molybdate per determination. Achieving these advantages of miniaturized volume, high precision and low cost, the design can also be used in automated in situ detection. PMID:29518059

Wide-Field Imaging Using Nitrogen Vacancies

NASA Technical Reports Server (NTRS)

Englund, Dirk Robert (Inventor); Trusheim, Matthew Edwin (Inventor)

2017-01-01

Nitrogen vacancies in bulk diamonds and nanodiamonds can be used to sense temperature, pressure, electromagnetic fields, and pH. Unfortunately, conventional sensing techniques use gated detection and confocal imaging, limiting the measurement sensitivity and precluding wide-field imaging. Conversely, the present sensing techniques do not require gated detection or confocal imaging and can therefore be used to image temperature, pressure, electromagnetic fields, and pH over wide fields of view. In some cases, wide-field imaging supports spatial localization of the NVs to precisions at or below the diffraction limit. Moreover, the measurement range can extend over extremely wide dynamic range at very high sensitivity.

SYSTEM OPTIMIZATION FOR THE AUTOMATIC SIMULTANEOUS DETERMINATION OF ARSENIC, SELENIUM, AND ANTIMONY, USING HYDRIDE GENERATION INTRODUCTION TO AN INDUCTIVELY COUPLED PLASMA.

USGS Publications Warehouse

Pyen, Grace S.; Browner, Richard F.; Long, Stephen

1986-01-01

A fixed-size simplex has been used to determine the optimum conditions for the simultaneous determination of arsenic, selenium, and antimony by hydride generation and inductively coupled plasma emission spectrometry. The variables selected for the simplex were carrier gas flow rate, rf power, viewing height, and reagent conditions. The detection limit for selenium was comparable to the preoptimized case, but there were twofold and fourfold improvements in the detection limits for arsenic and antimony, respectively. Precision of the technique was assessed with the use of artificially prepared water samples.

Censoring approach to the detection limits in X-ray fluorescence analysis

NASA Astrophysics Data System (ADS)

Pajek, M.; Kubala-Kukuś, A.

2004-10-01

We demonstrate that the effect of detection limits in the X-ray fluorescence analysis (XRF), which limits the determination of very low concentrations of trace elements and results in appearance of the so-called "nondetects", can be accounted for using the statistical concept of censoring. More precisely, the results of such measurements can be viewed as the left random censored data, which can further be analyzed using the Kaplan-Meier method correcting the data for the presence of nondetects. Using this approach, the results of measured, detection limit censored concentrations can be interpreted in a nonparametric manner including the correction for the nondetects, i.e. the measurements in which the concentrations were found to be below the actual detection limits. Moreover, using the Monte Carlo simulation technique we show that by using the Kaplan-Meier approach the corrected mean concentrations for a population of the samples can be estimated within a few percent uncertainties with respect of the simulated, uncensored data. This practically means that the final uncertainties of estimated mean values are limited in fact by the number of studied samples and not by the correction procedure itself. The discussed random-left censoring approach was applied to analyze the XRF detection-limit-censored concentration measurements of trace elements in biomedical samples.

Characterizing nonconstant instrumental variance in emerging miniaturized analytical techniques.

PubMed

Noblitt, Scott D; Berg, Kathleen E; Cate, David M; Henry, Charles S

2016-04-07

Measurement variance is a crucial aspect of quantitative chemical analysis. Variance directly affects important analytical figures of merit, including detection limit, quantitation limit, and confidence intervals. Most reported analyses for emerging analytical techniques implicitly assume constant variance (homoskedasticity) by using unweighted regression calibrations. Despite the assumption of constant variance, it is known that most instruments exhibit heteroskedasticity, where variance changes with signal intensity. Ignoring nonconstant variance results in suboptimal calibrations, invalid uncertainty estimates, and incorrect detection limits. Three techniques where homoskedasticity is often assumed were covered in this work to evaluate if heteroskedasticity had a significant quantitative impact-naked-eye, distance-based detection using paper-based analytical devices (PADs), cathodic stripping voltammetry (CSV) with disposable carbon-ink electrode devices, and microchip electrophoresis (MCE) with conductivity detection. Despite these techniques representing a wide range of chemistries and precision, heteroskedastic behavior was confirmed for each. The general variance forms were analyzed, and recommendations for accounting for nonconstant variance discussed. Monte Carlo simulations of instrument responses were performed to quantify the benefits of weighted regression, and the sensitivity to uncertainty in the variance function was tested. Results show that heteroskedasticity should be considered during development of new techniques; even moderate uncertainty (30%) in the variance function still results in weighted regression outperforming unweighted regressions. We recommend utilizing the power model of variance because it is easy to apply, requires little additional experimentation, and produces higher-precision results and more reliable uncertainty estimates than assuming homoskedasticity. Copyright © 2016 Elsevier B.V. All rights reserved.

Epidemiologic Evaluation of Measurement Data in the Presence of Detection Limits

PubMed Central

Lubin, Jay H.; Colt, Joanne S.; Camann, David; Davis, Scott; Cerhan, James R.; Severson, Richard K.; Bernstein, Leslie; Hartge, Patricia

2004-01-01

Quantitative measurements of environmental factors greatly improve the quality of epidemiologic studies but can pose challenges because of the presence of upper or lower detection limits or interfering compounds, which do not allow for precise measured values. We consider the regression of an environmental measurement (dependent variable) on several covariates (independent variables). Various strategies are commonly employed to impute values for interval-measured data, including assignment of one-half the detection limit to nondetected values or of “fill-in” values randomly selected from an appropriate distribution. On the basis of a limited simulation study, we found that the former approach can be biased unless the percentage of measurements below detection limits is small (5–10%). The fill-in approach generally produces unbiased parameter estimates but may produce biased variance estimates and thereby distort inference when 30% or more of the data are below detection limits. Truncated data methods (e.g., Tobit regression) and multiple imputation offer two unbiased approaches for analyzing measurement data with detection limits. If interest resides solely on regression parameters, then Tobit regression can be used. If individualized values for measurements below detection limits are needed for additional analysis, such as relative risk regression or graphical display, then multiple imputation produces unbiased estimates and nominal confidence intervals unless the proportion of missing data is extreme. We illustrate various approaches using measurements of pesticide residues in carpet dust in control subjects from a case–control study of non-Hodgkin lymphoma. PMID:15579415

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves.

PubMed

Katekhaye, S; Kale, M S; Laddha, K S

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C(18) column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r(2)>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves.

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves

PubMed Central

Katekhaye, S; Kale, M. S.; Laddha, K. S.

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C18 column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r2>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves. PMID:23204626

Single-spin stochastic optical reconstruction microscopy

PubMed Central

Pfender, Matthias; Aslam, Nabeel; Waldherr, Gerald; Neumann, Philipp; Wrachtrup, Jörg

2014-01-01

We experimentally demonstrate precision addressing of single-quantum emitters by combined optical microscopy and spin resonance techniques. To this end, we use nitrogen vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers, we are able to simultaneously perform sub–diffraction-limit imaging and optically detected spin resonance (ODMR) measurements on NV spins. This allows the assignment of spin resonance spectra to individual NV center locations with nanometer-scale resolution and thus further improves spatial discrimination. For example, we resolved formerly indistinguishable emitters by their spectra. Furthermore, ODMR spectra contain metrology information allowing for sub–diffraction-limit sensing of, for instance, magnetic or electric fields with inherently parallel data acquisition. As an example, we have detected nuclear spins with nanometer-scale precision. Finally, we give prospects of how this technique can evolve into a fully parallel quantum sensor for nanometer resolution imaging of delocalized quantum correlations. PMID:25267655

A sensitive and rapid determination of ranitidine in human plasma by HPLC with fluorescence detection and its application for a pharmacokinetic study.

PubMed

Ulu, Sevgi Tatar; Tuncel, Muzaffer

2012-04-01

A novel precolumn derivatization reversed-phase high-performance liquid chromatography method with fluorescence detection is described for the determination of ranitidine in human plasma. The method was based on the reaction of ranitidine with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole forming yellow colored fluorescent product. The separation was achieved on a C(18) column using methanol-water (60:40, v/v) mobile phase. Fluorescence detection was used at the excitation and emission of 458 and 521 nm, respectively. Lisinopril was utilized as an internal standard. The flow rate was 1.2 mL/min. Ranitidine and lisinopril appeared at 3.24 and 2.25 min, respectively. The method was validated for system suitability, precision, accuracy, linearity, limit of detection, limit of quantification, recovery and robustness. Intra- and inter-day precisions of the assays were in the range of 0.01-0.44%. The assay was linear over the concentration range of 50-2000 ng/mL. The mean recovery was determined to be 96.40 ± 0.02%. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (150 mg) of ranitidine. © The Author [2012]. Published by Oxford University Press. All rights reserved.

[Comparative data regarding two HPLC methods for determination of isoniazid].

PubMed

Gârbuleţ, Daniela; Spac, A F; Dorneanu, V

2009-01-01

For the determination of isoniazide (isonicotinic acid hydrazide - HIN) two different HPLC methods were developed and validated. Both experiments were performed using a Waters 2695 liquid chromatograph and a UV - Waters 2489 detector. The first method (I) used a Nucleosil 100-10 C18 column (250 x 4.6 mm), a mobile phase formed by a mixture of acetonitrile/10(-2) M oxalic acid (80/20) and a flow of 1.5 mL/ min; detection was done at 230 nm. The second method (II) used a Luna 100-5 C18 column (250 x 4.6 mm), a mobile phase formed by a mixture of methanol/acetate buffer, pH = 5.0 (20/ 80), a flow of 1 mL/min; detection was done at 270 nm. Both methods were validated, the correlation coefficients were 0.9998 (I) and 0.9999 (II), the detection limits were 0.6 microg/mL (I) and 0.055 microg/mL (II), the quantitation limits were 1.9 microg/mL (I) and 0.2 microg/ mL (II). There were also studied: the system precision (RSD = 0.1692% (I) and 0.2000% (II)), the method precision (RSD = 1.1844% (I) and 0.6170% (II)) and the intermediate precision (RSD = 1.8058% (I) and 0.5970% (II)). The accuracy was good, the calculated recoveries were 102.66% (I) and 101.36 (II). Both validated methods were applied for HIN determination from tablets with good and comparable results.

Validation of minicams for measuring concentrations of chemical agent in environmental air

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

Menton, R.G.; Hayes, T.L.; Chou, Y.L.

1993-05-13

Environmental monitoring for chemical agents is necessary to ensure that notification and appropriate action will be taken in the, event that there is a release exceeding control limits of such agents into the workplace outside of engineering controls. Prior to implementing new analytical procedures for environmental monitoring, precision and accuracy (PA) tests are conducted to ensure that an agent monitoring system performs according to specified accuracy, precision, and sensitivity requirements. This testing not only establishes the accuracy and precision of the method, but also determines what factors can affect the method's performance. Performance measures that are particularly important in agentmore » monitoring include the Detection Limit (DL), Decision Limit (DC), Found Action Level (FAL), and the Target Action Level (TAL). PA experiments were performed at Battelle's Medical Research and Evaluation Facility (MREF) to validate the use of the miniature chemical agent monitoring system (MINICAMs) for measuring environmental air concentrations of sulfur mustard (HD). This presentation discusses the experimental and statistical approaches for characterizing the performance of MINICAMS for measuring HD in air.« less

Evaluating the utility of syndromic surveillance algorithms for screening to detect potentially clonal hospital infection outbreaks

PubMed Central

Talbot, Thomas R; Schaffner, William; Bloch, Karen C; Daniels, Titus L; Miller, Randolph A

2011-01-01

Objective The authors evaluated algorithms commonly used in syndromic surveillance for use as screening tools to detect potentially clonal outbreaks for review by infection control practitioners. Design Study phase 1 applied four aberrancy detection algorithms (CUSUM, EWMA, space-time scan statistic, and WSARE) to retrospective microbiologic culture data, producing a list of past candidate outbreak clusters. In phase 2, four infectious disease physicians categorized the phase 1 algorithm-identified clusters to ascertain algorithm performance. In phase 3, project members combined the algorithms to create a unified screening system and conducted a retrospective pilot evaluation. Measurements The study calculated recall and precision for each algorithm, and created precision-recall curves for various methods of combining the algorithms into a unified screening tool. Results Individual algorithm recall and precision ranged from 0.21 to 0.31 and from 0.053 to 0.29, respectively. Few candidate outbreak clusters were identified by more than one algorithm. The best method of combining the algorithms yielded an area under the precision-recall curve of 0.553. The phase 3 combined system detected all infection control-confirmed outbreaks during the retrospective evaluation period. Limitations Lack of phase 2 reviewers' agreement indicates that subjective expert review was an imperfect gold standard. Less conservative filtering of culture results and alternate parameter selection for each algorithm might have improved algorithm performance. Conclusion Hospital outbreak detection presents different challenges than traditional syndromic surveillance. Nevertheless, algorithms developed for syndromic surveillance have potential to form the basis of a combined system that might perform clinically useful hospital outbreak screening. PMID:21606134

Development of the fast and efficient gamma detector using Cherenkov light for TOF-PET

NASA Astrophysics Data System (ADS)

Canot, C.; Alokhina, M.; Abbon, P.; Bard, J. P.; Tauzin, G.; Yvon, D.; Sharyy, V.

2017-12-01

In this paper we present two configurations of innovative gamma detectors using Cherenkov light for time-of-flight—Positron Emission Tomography (PET). The first uses heavy crystals as a Cherenkov radiator to develop a demonstrator for a whole body PET scanner with high detection efficiency. We demonstrated a 30% detection efficiency and a 180 ps (FWHM) time resolution, mainly limited by the time transit spread of the photomultiplier. The second configuration uses an innovative liquid, the TriMethyl Bismuth, to develop a high precision brain-scanning PET device with time-of-flight capability. According to Geant4 simulation, we expect to reach a precision of 150 ps (FWHM) and an efficiency of about 25%.

Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation

PubMed Central

Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

2014-01-01

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75 ÷ 12.50 μg·spot−1, and from 1.00 ÷ 2.50 μg·spot−1 for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1 and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia. PMID:24526880

Validation of a thin-layer chromatography for the determination of hydrocortisone acetate and lidocaine in a pharmaceutical preparation.

PubMed

Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

2014-01-01

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform+acetone+ammonia (25%) in volume composition 8:2:0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75÷12.50  μg·spot(-1), and from 1.00÷2.50  μg·spot(-1) for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198  μg·spot(-1) and LOD is 0.066  μg·spot(-1). LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090  μg·spot(-1), respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia.

Fiber Scrambling for Extreme Doppler Precision

NASA Astrophysics Data System (ADS)

Spronck, Julien; Kaplan, Z.; Fischer, D.

2011-09-01

The detection of Earth-like exoplanets with the radial velocity method requires extreme Doppler precision and long-term stability in order to measure tiny reflex velocities in the host star. Recent planet searches have led to the detection of so called “super-Earths” (up to a few Earth masses) that induce radial velocity changes of about 1 m/s. However, the detection of true Earth analogs requires a precision of 10 cm/s. One of the factors limiting Doppler precision is variation in the Point Spread Function (PSF) from observation to observation due to changes in the illumination of the slit and spectrograph optics. Thus, this stability has become a focus of current instrumentation work. Fiber optics have been used since the 1980’s to couple telescopes to high-precision spectrographs, initially for simpler mechanical design and control. However, fiber optics are also naturally efficient scramblers. Scrambling refers to a fiber’s ability to produce an output beam independent of input. Our research is focused on understanding the scrambling properties of fibers with different geometries (circular, square, octagonal), different lengths and fiber sizes. Another important parameter when it comes to fibers is the so-called focal ratio degradation (FRD), which accounts for a different (faster) focal ratio after the fiber than the one sent into the fiber. In this paper, we will present new insight on fiber scrambling, FRD and what we call fiber personality, which describes differing behaviors for supposedly identical fiber.

The combination design for open and endoscopic surgery using fluorescence molecular imaging technology

NASA Astrophysics Data System (ADS)

Mao, Yamin; Jiang, Shixin; Ye, Jinzuo; An, Yu; Yang, Xin; Chi, Chongwei; Tian, Jie

2015-03-01

For clinical surgery, it is still a challenge to objectively determine tumor margins during surgery. With the development of medical imaging technology, fluorescence molecular imaging (FMI) method can provide real-time intraoperative tumor margin information. Furthermore, surgical navigation system based on FMI technology plays an important role for the aid of surgeons' precise tumor margin decision. However, detection depth is the most limitation exists in the FMI technique and the method convenient for either macro superficial detection or micro deep tissue detection is needed. In this study, we combined advantages of both open surgery and endoscopic imaging systems with FMI technology. Indocyanine green (ICG) experiments were performed to confirm the feasibility of fluorescence detection in our system. Then, the ICG signal was photographed in the detection area with our system. When the system connected with endoscope lens, the minimum quantity of ICG detected by our system was 0.195 ug. For aspect of C mount lens, the sensitivity of ICG detection with our system was 0.195ug. Our experiments results proved that it was feasible to detect fluorescence images with this combination method. Our system shows great potential in the clinical applications of precise dissection of various tumors

An ATMND/SGI based label-free and fluorescence ratiometric aptasensor for rapid and highly sensitive detection of cocaine in biofluids.

PubMed

Wang, Jiamian; Song, Jie; Wang, Xiuyun; Wu, Shuo; Zhao, Yanqiu; Luo, Pinchen; Meng, Changgong

2016-12-01

A label-free ratiometric fluorescence aptasensor has been developed for the rapid and sensitive detection of cocaine in complex biofluids. The fluorescent aptasensor is composed of a non-labeled GC-38 cocaine aptamer which serves as a basic sensing unit and two fluorophores, 2-amino-5,6,7-trimethyl-1,8-naphthyridine (ATMND) and SYBR Green I (SGI) which serves as a signal reporter and a build-in reference, respectively. The detection principle is based on a specific cocaine mediated ATMND displacement reaction and the corresponding change in the fluorescence ratio of ATMND to SGI. Due to the high affinity of the non-labeled aptamer, the good precision originated from the ratiometric method, and the good fluorescence quantum yield of the fluorophore, the aptasensor shows good analytical performance with respect to cocaine detection. Under optimal conditions, the aptasensor shows a linear range of 0.10-10μM and a low limit of detection of 56nM, with a fast response of 20s. The low limit of detection is comparable to most of the fluorescent aptasensors with signal amplification strategies and much lower than all of the unamplified cocaine aptasensors. Practical sample analysis in a series of complex biofluids, including urine, saliva and serum, also indicates the good precision, stability, and high sensitivity of the aptasensor, which may have great potential for the point-of-care screening of cocaine in complex biofluids. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of cocaine, benzoylecgonine, cocaethylene and norcocaine in human hair using solid-phase extraction and liquid chromatography with tandem mass spectrometric detection.

PubMed

Moore, Christine; Coulter, Cynthia; Crompton, Katherine

2007-11-15

A quantitative analytical procedure for the determination of cocaine, benzoylecgonine and cocaethylene and norcocaine in hair has been developed and validated. The hair samples were washed, incubated, and any drugs present were quantified using mixed mode solid-phase extraction and liquid chromatography with tandem mass spectrometric detection in positive atmospheric pressure chemical ionization mode. For confirmation, two transitions were monitored and one ion ratio was determined, which was within 20% of that of the known calibration standards. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion limited the sensitivity of the assay, particularly for benzoylecgonine, however, the additional confidence in the final result as well as forensic defensibility were considered to be of greater importance. Even with simultaneous monitoring, the concentrations proposed by the United States Federal guidelines for hair analysis were achieved. The limits of quantitation were 50 pg/mg; the limit of detection was 25 pg/mg. The intra-day precision of the assays at 100 pg/mg (n=5) was 1.3%, 8.1%, 0.8% and 0.4%; inter-day precision 4.8%, 9.2%, 15.7% and 12.6% (n=10) for cocaine, benzoylecgonine, cocaethylene and norcocaine, respectively. The methods were applied to both proficiency specimens and to samples obtained during research studies in the USA.

Quantum state reconstruction and photon number statistics for low dimensional semiconductor opto-electronic devices

NASA Astrophysics Data System (ADS)

Böhm, Fabian; Grosse, Nicolai B.; Kolarczik, Mirco; Herzog, Bastian; Achtstein, Alexander; Owschimikow, Nina; Woggon, Ulrike

2017-09-01

Quantum state tomography and the reconstruction of the photon number distribution are techniques to extract the properties of a light field from measurements of its mean and fluctuations. These techniques are particularly useful when dealing with macroscopic or mesoscopic systems, where a description limited to the second order autocorrelation soon becomes inadequate. In particular, the emission of nonclassical light is expected from mesoscopic quantum dot systems strongly coupled to a cavity or in systems with large optical nonlinearities. We analyze the emission of a quantum dot-semiconductor optical amplifier system by quantifying the modifications of a femtosecond laser pulse propagating through the device. Using a balanced detection scheme in a self-heterodyning setup, we achieve precise measurements of the quadrature components and their fluctuations at the quantum noise limit1. We resolve the photon number distribution and the thermal-to-coherent evolution in the photon statistics of the emission. The interferometric detection achieves a high sensitivity in the few photon limit. From our data, we can also reconstruct the second order autocorrelation function with higher precision and time resolution compared with classical Hanbury Brown-Twiss experiments.

Rapid analysis of 3,4-methylenedioxymethamphetamine: a comparison of nonaqueous capillary electrophoresis/fluorescence detection with GC/MS.

PubMed

Fang, Ching; Chung, Yu-Lin; Liu, Ju-Tsung; Lin, Cheng-Huang

2002-02-18

Because of the increasing use of 3,4-methylenedioxymethamphetamine (3,4-MDMA), a rapid and sensitive analytical technique is required for its detection and determination. Using nonaqueous capillary electrophoresis/fluorescence spectroscopy (NACE/FS) detection, it is possible to determine this drug at the level 0.5 ppm without any pre-treatment in less than 5 min. After liquid-liquid extraction, the sample can be condensed and a detection limit of 3,4-MDMA in urine of 50 ppb (S/N = 3) can be achieved. The precision of the method was evaluated by measuring the repeatability and intermediate precision of migration time and the corrected peak height by comparison with a 3,4-MDMA-D5 internal standard. With the conventional GC/MS method, it is necessary to derivatize the 3,4-MDMA before injection and the GC migration time also is in excess of 20 min. Therefore, NACE/FS represents a good complementary method to GC/MS for use in forensic analysis.

Corkscrew point spread function for far-field three-dimensional nanoscale localization of pointlike objects

PubMed Central

Lew, Matthew D.; Lee, Steven F.; Badieirostami, Majid; Moerner, W. E.

2011-01-01

We describe the corkscrew point spread function (PSF), which can localize objects in three dimensions throughout a 3.2 µm depth of field with nanometer precision. The corkscrew PSF rotates as a function of the axial (z) position of an emitter. Fisher information calculations show that the corkscrew PSF can achieve nanometer localization precision with limited numbers of photons. We demonstrate three-dimensional super-resolution microscopy with the corkscrew PSF by imaging beads on the surface of a triangular polydimethylsiloxane (PDMS) grating. With 99,000 photons detected, the corkscrew PSF achieves a localization precision of 2.7 nm in x, 2.1 nm in y, and 5.7 nm in z. PMID:21263500

Corkscrew point spread function for far-field three-dimensional nanoscale localization of pointlike objects.

PubMed

Lew, Matthew D; Lee, Steven F; Badieirostami, Majid; Moerner, W E

2011-01-15

We describe the corkscrew point spread function (PSF), which can localize objects in three dimensions throughout a 3.2 μm depth of field with nanometer precision. The corkscrew PSF rotates as a function of the axial (z) position of an emitter. Fisher information calculations show that the corkscrew PSF can achieve nanometer localization precision with limited numbers of photons. We demonstrate three-dimensional super-resolution microscopy with the corkscrew PSF by imaging beads on the surface of a triangular polydimethylsiloxane (PDMS) grating. With 99,000 photons detected, the corkscrew PSF achieves a localization precision of 2.7 nm in x, 2.1 nm in y, and 5.7 nm in z.

Direct phase-locking of a 8.6-μm quantum cascade laser to a mid-IR optical frequency comb: application to precision spectroscopy of N2O.

PubMed

Gambetta, Alessio; Cassinerio, Marco; Coluccelli, Nicola; Fasci, Eugenio; Castrillo, Antonio; Gianfrani, Livio; Gatti, Davide; Marangoni, Marco; Laporta, Paolo; Galzerano, Gianluca

2015-02-01

We developed a high-precision spectroscopic system at 8.6 μm based on direct heterodyne detection and phase-locking of a room-temperature quantum-cascade-laser against an harmonic, 250-MHz mid-IR frequency comb obtained by difference-frequency generation. The ∼30  dB signal-to-noise ratio of the detected beat-note together with the achieved closed-loop locking bandwidth of ∼500  kHz allows for a residual integrated phase noise of 0.78 rad (1 Hz-5 MHz), for an ultimate resolution of ∼21  kHz, limited by the measured linewidth of the mid-IR comb. The system was used to perform absolute measurement of line-center frequencies for the rotational components of the ν2 vibrational band of N2O, with a relative precision of 3×10(-10).

The Kepler Mission: A Photometric Search for Earthlike Planets

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.; Borucki, William; Koch, David; Young, Richard E. (Technical Monitor)

1998-01-01

If Earth lies in or near the orbital plane of an extrasolar planet, that planet passes in front of the disk of its star once each orbit as viewed from Earth. Precise photometry can reveal such transits, which can be distinguished from rotationally-modulated starspots and intrinsic stellar variability by their periodicity, square-well shapes and relative spectral neutrality. Transit observations would provide the size and orbital period of the detected planet. Although geometrical considerations limit the fraction of planets detectable by this technique, many stars can be surveyed within the field of view of one telescope, so transit photometry is quite efficient. Scintillation in and variability of Earth's atmosphere limit photometric precision to roughly one-thousandth of a magnitude, allowing detection of transits by Jupiter-sized planets but not by Earth-sized planets from the ground. The COROT spacecraft will be able to detect Uranus-sized planets orbiting near stars. The Kepler Mission, which is being proposed to NASA's Discovery Program this year, will have a photometer with a larger aperture (1 meter) than will COROT, so it will be able to detect transits by planets as small as Earth. Moreover, the Kepler mission will examine the same star field for four years, allowing confirmation of planets with orbital periods of a year. If the Sun's planetary system is typical for single stars, Kepler should detect approximately 480 terrestrial planets. Assuming the statistics from radial velocity surveys are typical, Kepler should also detect transits of 150 inner giant planets and reflected light variations of 1400 giant planets with orbital periods of less than one week.

Stability Indicating Reverse Phase HPLC Method for Estimation of Rifampicin and Piperine in Pharmaceutical Dosage Form.

PubMed

Shah, Umang; Patel, Shraddha; Raval, Manan

2018-01-01

High performance liquid chromatography is an integral analytical tool in assessing drug product stability. HPLC methods should be able to separate, detect, and quantify the various drug-related degradants that can form on storage or manufacturing, plus detect any drug-related impurities that may be introduced during synthesis. A simple, economic, selective, precise, and stability-indicating HPLC method has been developed and validated for analysis of Rifampicin (RIFA) and Piperine (PIPE) in bulk drug and in the formulation. Reversed-phase chromatography was performed on a C18 column with Buffer (Potassium Dihydrogen Orthophosphate) pH 6.5 and Acetonitrile, 30:70), (%, v/v), as mobile phase at a flow rate of 1 mL min-1. The detection was performed at 341 nm and sharp peaks were obtained for RIFA and PIPE at retention time of 3.3 ± 0.01 min and 5.9 ± 0.01 min, respectively. The detection limits were found to be 2.385 ng/ml and 0.107 ng/ml and quantification limits were found to be 7.228ng/ml and 0.325ng/ml for RIFA and PIPE, respectively. The method was validated for accuracy, precision, reproducibility, specificity, robustness, and detection and quantification limits, in accordance with ICH guidelines. Stress study was performed on RIFA and PIPE and it was found that these degraded sufficiently in all applied chemical and physical conditions. Thus, the developed RP-HPLC method was found to be suitable for the determination of both the drugs in bulk as well as stability samples of capsule containing various excipients. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Application of HPLC with ELSD Detection for the Assessment of Azelaic Acid Impurities in Liposomal Formulation

PubMed Central

Han, Stanislaw; Karlowicz-Bodalska, Katarzyna; Ozimek, Lukasz

2013-01-01

In the course of research and development of a new pharmaceutical formulation of azelaic acid in the liposomal form, we developed a rapid and accurate method for the detection of impurities using high-performance liquid chromatography. A chromatographic column from Merck (Purospher Star RP C18, 250–4 mm (5 μm) was used in the assay, and the mobile phase gradient consisted of three phases: A—methanol : water (5 : 95) + 1.5% (v/v) acetic acid; B—water : methanol (5 : 95) + 1.5% (v/v) acetic acid; and C—chloroform. Detection of the impurities and the active substance was performed by an evaporative light-scattering detector. The method was validated for selectivity, system precision, method precision, limit of detection, and response rates. The proposed method can be used to detect impurities in the liposomal formulation of azelaic acid. The method enables separation of azelaic acid from the identified and unidentified impurities and from the excipients used in the drug form. PMID:24228008

Application of HPLC with ELSD detection for the assessment of azelaic acid impurities in liposomal formulation.

PubMed

Han, Stanislaw; Karlowicz-Bodalska, Katarzyna; Szura, Dorota; Ozimek, Lukasz; Musial, Witold

2013-01-01

In the course of research and development of a new pharmaceutical formulation of azelaic acid in the liposomal form, we developed a rapid and accurate method for the detection of impurities using high-performance liquid chromatography. A chromatographic column from Merck (Purospher Star RP C18, 250-4 mm (5 μm) was used in the assay, and the mobile phase gradient consisted of three phases: A--methanol : water (5 : 95) + 1.5% (v/v) acetic acid; B--water : methanol (5 : 95) + 1.5% (v/v) acetic acid; and C--chloroform. Detection of the impurities and the active substance was performed by an evaporative light-scattering detector. The method was validated for selectivity, system precision, method precision, limit of detection, and response rates. The proposed method can be used to detect impurities in the liposomal formulation of azelaic acid. The method enables separation of azelaic acid from the identified and unidentified impurities and from the excipients used in the drug form.

Determination of MDMA, MDEA and MDA in urine by high performance liquid chromatography with fluorescence detection.

PubMed

da Costa, José Luiz; da Matta Chasin, Alice Aparecida

2004-11-05

This paper describes the development and validation of analytical methodology for the determination of the use of MDMA, MDEA and MDA in urine. After a simple liquid extraction, the analyses were carried out on a high performance liquid chromatography (HPLC) in an octadecyl column, with fluorescence detection. The mobile phase using a sodium dodecyl sulfate ion-pairing reagent allows good separation and efficiency. The method showed good linearity and precision. Recovery was between 85 and 102% and detection limits were 10, 15 and 20 ng/ml for MDA, MDMA and MDEA, respectively. No interfering substances were detected with fluorescence detection.

One-step liquid-liquid extraction of cocaine from urine samples for gas chromatographic analysis.

PubMed

Farina, Marcelo; Yonamine, Maurício; Silva, Ovandir A

2002-07-17

An improved technique for cocaine extraction from urine samples for gas chromatographic (GC) analysis is described. Employing a simple liquid-liquid extraction (LLE) of cocaine with a mixture of ethyl ether:isopropanol (9:1) the method presents a mean recovery of 74.49%. Limit of detection (LOD) and limit of quantification (LOQ) were 5 and 20 ng/ml, respectively. The method is highly precise (coefficient of variation (CV) <8%) and linear from 20 to 2000 ng/ml. It can he applied to detect the presence of cocaine in urine as a marker of its recent use in drug abuse treatment protocols.

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

Bertucci, M.; Michelato, P.; Moretti, M.

X-ray fluorescence probe for detection of foreign material inclusions on the inner surface of superconducting cavities has been developed and tested. The setup detects trace element content such as a few micrograms of impurities responsible for thermal breakdown phenomena limiting the cavity performance. The setup has been customized for the geometry of 1.3 GHz TESLA-type niobium cavities and focuses on the surface of equator area at around 103 mm from the centre axis of the cavities with around 20 mm detection spot. More precise localization of inclusions can be reconstructed by means of angular or lateral displacement of the cavity.more » Preliminary tests confirmed a very low detection limit for elements laying in the high efficiency spectrum zone (from 5 to 10 keV), and a high angular resolution allowing an accurate localization of defects within the equator surface.« less

Fiber Scrambling for High Precision Spectrographs

NASA Astrophysics Data System (ADS)

Kaplan, Zachary; Spronck, J. F. P.; Fischer, D.

2011-05-01

The detection of Earth-like exoplanets with the radial velocity method requires extreme Doppler precision and long-term stability in order to measure tiny reflex velocities in the host star. Recent planet searches have led to the detection of so called "super-Earths” (up to a few Earth masses) that induce radial velocity changes of about 1 m/s. However, the detection of true Earth analogs requires a precision of 10 cm/s. One of the largest factors limiting Doppler precision is variation in the Point Spread Function (PSF) from observation to observation due to changes in the illumination of the slit and spectrograph optics. Thus, this stability has become a focus of current instrumentation work. Fiber optics have been used since the 1980's to couple telescopes to high-precision spectrographs, initially for simpler mechanical design and control. However, fiber optics are also naturally efficient scramblers. Scrambling refers to a fiber's ability to produce an output beam independent of input. Our research is focused on characterizing the scrambling properties of several types of fibers, including circular, square and octagonal fibers. By measuring the intensity distribution after the fiber as a function of input beam position, we can simulate guiding errors that occur at an observatory. Through this, we can determine which fibers produce the most uniform outputs for the severest guiding errors, improving the PSF and allowing sub-m/s precision. However, extensive testing of fibers of supposedly identical core diameter, length and shape from the same manufacturer has revealed the "personality” of individual fibers. Personality describes differing intensity patterns for supposedly duplicate fibers illuminated identically. Here, we present our results on scrambling characterization as a function of fiber type, while studying individual fiber personality.

Multimodal autofluorescence detection of cancer: from single cells to living organism

NASA Astrophysics Data System (ADS)

Horilova, J.; Cunderlikova, B.; Cagalinec, M.; Chorvat, D.; Marcek Chorvatova, A.

2018-02-01

Multimodal optical imaging of suspected tissues is showing to be a promising method for distinguishing suspected cancerous tissues from healthy ones. In particular, the combination of steady-state spectroscopic methods with timeresolved fluorescence provides more precise insight into native metabolism when focused on tissue autofluorescence. Cancer is linked to specific metabolic remodelation detectable spectroscopically. In this work, we evaluate possibilities and limitations of multimodal optical cancer detection in single cells, collagen-based 3D cell cultures and in living organisms (whole mice), as a representation of gradually increasing complexity of model systems.

Low level vapor verification of monomethyl hydrazine

NASA Technical Reports Server (NTRS)

Mehta, Narinder

1990-01-01

The vapor scrubbing system and the coulometric test procedure for the low level vapor verification of monomethyl hydrazine (MMH) are evaluated. Experimental data on precision, efficiency of the scrubbing liquid, instrument response, detection and reliable quantitation limits, stability of the vapor scrubbed solution, and interference were obtained to assess the applicability of the method for the low ppb level detection of the analyte vapor in air. The results indicated that the analyte vapor scrubbing system and the coulometric test procedure can be utilized for the quantitative detection of low ppb level vapor of MMH in air.

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica

PubMed Central

Naveen, P.; Lingaraju, H. B.; Prasad, K. Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica, is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica. RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography–mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica. SUMMARY The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica. The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica. Abbreviations Used: M. indica: Mangifera indica, RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification. PMID:28539748

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica.

PubMed

Naveen, P; Lingaraju, H B; Prasad, K Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica , is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica . RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography-mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica . The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica . The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica . Abbreviations Used: M. indica : Mangifera indica , RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification.

Comparison of low cost measurement techniques for long-term monitoring of atmospheric ammonia.

PubMed

Sutton, M A; Miners, B; Tang, Y S; Milford, C; Wyers, G P; Duyzer, J H; Fowler, D

2001-10-01

An inter-comparison of techniques for long-term sampling of atmospheric ammonia (NH3) was conducted with a view to establishing a national network with > 50 sites. Key requirements were for: a low cost system, simplicity and durability to enable a postal exchange with local site operators, a precision of < +/- 20% for monthly sampling at expected NH3 concentrations of 1-2 micrograms m-3, a detection limit sufficient to resolve the small NH3 concentrations (< 0.2 microgram m-3) expected in remote parts of the UK, and a quantitative means to establish quality control. Five sampling methods were compared: A, a commercially available membrane diffusion tube (exposed in triplicate), with membranes removed immediately after sampling; B, the above method, with the membranes left in place until analysis; C, open-ended diffusion tubes (exposed with 4 replicates); D, a new active sampling diffusion denuder system; and E, an active sampling bubbler system. Method D consisted of two 0.1 m acid coated glass denuders in series with sampling at approximately 0.3 l min-1. These methods were deployed at 6 locations in the UK and the Netherlands and compared against reference estimates. Method D was the most precise and sensitive of the techniques compared, with a detection limit of < 0.1 microgram m-3. The bubbler provided a less precise estimate of NH3 concentration, and also suffered several practical drawbacks. The diffusion tubes were found to correlate with the reference at high concentrations (> 3 micrograms m-3), but were less precise and overestimated NH3 at smaller concentrations. Of the passive methods, A was the most precise and C the least precise. On the basis of the results, method D has been implemented in the national network, together with application of method A to explore spatial variability in regions with expected high NH3 concentrations.

Analysis of the accuracy and precision of the McMaster method in detection of the eggs of Toxocara and Trichuris species (Nematoda) in dog faeces.

PubMed

Kochanowski, Maciej; Dabrowska, Joanna; Karamon, Jacek; Cencek, Tomasz; Osiński, Zbigniew

2013-07-01

The aim of this study was to determine the accuracy and precision of McMaster method with Raynaud's modification in the detection of the eggs of the nematodes Toxocara canis (Werner, 1782) and Trichuris ovis (Abildgaard, 1795) in faeces of dogs. Four variants of McMaster method were used for counting: in one grid, two grids, the whole McMaster chamber and flotation in the tube. One hundred sixty samples were prepared from dog faeces (20 repetitions for each egg quantity) containing 15, 25, 50, 100, 150, 200, 250 and 300 eggs of T. canis and T. ovis in 1 g of faeces. To compare the influence of kind of faeces on the results, samples of dog faeces were enriched at the same levels with the eggs of another nematode, Ascaris suum Goeze, 1782. In addition, 160 samples of pig faeces were prepared and enriched only with A. suum eggs in the same way. The highest limit of detection (the lowest level of eggs that were detected in at least 50% of repetitions) in all McMaster chamber variants were obtained for T. canis eggs (25-250 eggs/g faeces). In the variant with flotation in the tube, the highest limit of detection was obtained for T. ovis eggs (100 eggs/g). The best results of the limit of detection, sensitivity and the lowest coefficients of variation were obtained with the use of the whole McMaster chamber variant. There was no significant impact of properties of faeces on the obtained results. Multiplication factors for the whole chamber were calculated on the basis of the transformed equation of the regression line, illustrating the relationship between the number of detected eggs and that of the eggs added to the'sample. Multiplication factors calculated for T. canis and T. ovis eggs were higher than those expected using McMaster method with Raynaud modification.

Precision Orbit of δ Delphini and Prospects for Astrometric Detection of Exoplanets

NASA Astrophysics Data System (ADS)

Gardner, Tyler; Monnier, John D.; Fekel, Francis C.; Williamson, Mike; Duncan, Douglas K.; White, Timothy R.; Ireland, Michael; Adams, Fred C.; Barman, Travis; Baron, Fabien; ten Brummelaar, Theo; Che, Xiao; Huber, Daniel; Kraus, Stefan; Roettenbacher, Rachael M.; Schaefer, Gail; Sturmann, Judit; Sturmann, Laszlo; Swihart, Samuel J.; Zhao, Ming

2018-03-01

Combining visual and spectroscopic orbits of binary stars leads to a determination of the full 3D orbit, individual masses, and distance to the system. We present a full analysis of the evolved binary system δ Delphini using astrometric data from the MIRC and PAVO instruments on the CHARA long-baseline interferometer, 97 new spectra from the Fairborn Observatory, and 87 unpublished spectra from the Lick Observatory. We determine the full set of orbital elements for δ Del, along with masses of 1.78 ± 0.07 M ⊙ and 1.62 ± 0.07 M ⊙ for each component, and a distance of 63.61 ± 0.89 pc. These results are important in two contexts: for testing stellar evolution models and for defining the detection capabilities for future planet searches. We find that the evolutionary state of this system is puzzling, as our measured flux ratios, radii, and masses imply a ∼200 Myr age difference between the components, using standard stellar evolution models. Possible explanations for this age discrepancy include mass transfer scenarios with a now-ejected tertiary companion. For individual measurements taken over a span of two years, we achieve <10 μas precision on the differential position with 10 minute observations. The high precision of our astrometric orbit suggests that exoplanet detection capabilities are within reach of MIRC at CHARA. We compute exoplanet detection limits around δ Del and conclude that, if this precision is extended to wider systems, we should be able to detect most exoplanets >2 M J on orbits >0.75 au around individual components of hot binary stars via differential astrometry.

Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples.

PubMed

Pano-Farias, Norma S; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Jurado, José M; Muñiz-Valencia, Roberto

2015-04-01

To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 μg/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ˂450 μg/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multitemporal spectroscopy for crop stress detection using band selection methods

NASA Astrophysics Data System (ADS)

Mewes, Thorsten; Franke, Jonas; Menz, Gunter

2008-08-01

A fast and precise sensor-based identification of pathogen infestations in wheat stands is essential for the implementation of site-specific fungicide applications. Several works have shown possibilities and limitations for the detection of plant stress using spectral sensor data. Hyperspectral data provide the opportunity to collect spectral reflectance in contiguous bands over a broad range of the electromagnetic spectrum. Individual phenomena like the light absorption of leaf pigments can be examined in detail. The precise knowledge of stress-dependent shifting in certain spectral wavelengths provides great advantages in detecting fungal infections. This study focuses on band selection techniques for hyperspectral data to identify relevant and redundant information in spectra regarding a detection of plant stress caused by pathogens. In a laboratory experiment, five 1 sqm boxes with wheat were multitemporarily measured by a ASD Fieldspec® 3 FR spectroradiometer. Two stands were inoculated with Blumeria graminis - the pathogen causing powdery mildew - and one stand was used to simulate the effect of water deficiency. Two stands were kept healthy as control stands. Daily measurements of the spectral reflectance were taken over a 14-day period. Three ASD Pro Lamps were used to illuminate the plots with constant light. By applying band selection techniques, the three types of different wheat vitality could be accurately differentiated at certain stages. Hyperspectral data can provide precise information about pathogen infestations. The reduction of the spectral dimension of sensor data by means of band selection procedures is an appropriate method to speed up the data supply for precision agriculture.

The neuromechanics of hearing

NASA Astrophysics Data System (ADS)

Araya, Mussie K.; Brownell, William E.

2015-12-01

Hearing requires precise detection and coding of acoustic signals by the inner ear and equally precise communication of the information through the auditory brainstem. A membrane based motor in the outer hair cell lateral wall contributes to the transformation of sound into a precise neural code. Structural, molecular and energetic similarities between the outer hair cell and auditory brainstem neurons suggest that a similar membrane based motor may contribute to signal processing in the auditory CNS. Cooperative activation of voltage gated ion channels enhances neuronal temporal processing and increases the upper frequency limit for phase locking. We explore the possibility that membrane mechanics contribute to ion channel cooperativity as a consequence of the nearly instantaneous speed of electromechanical signaling and the fact that membrane composition and mechanics modulate ion channel function.

Detection of β-Lactams and Chloramphenicol Residues in Raw Milk-Development and Application of an HPLC-DAD Method in Comparison with Microbial Inhibition Assays.

PubMed

Karageorgou, Eftychia; Christoforidou, Sofia; Ioannidou, Maria; Psomas, Evdoxios; Samouris, Georgios

2018-06-01

The present study was carried out to assess the detection sensitivity of four microbial inhibition assays (MIAs) in comparison with the results obtained by the High Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) method for antibiotics of the β-lactam group and chloramphenicol in fortified raw milk samples. MIAs presented fairly good results when detecting β-lactams, whereas none were able to detect chloramphenicol at or above the permissible limits. HPLC analysis revealed high recoveries of examined compounds, whereas all detection limits observed were lower than their respective maximum residue limits (MRL) values. The extraction and clean-up procedure of antibiotics was performed by a modified matrix solid phase dispersion procedure using a mixture of Plexa by Agilent and QuEChERS as a sorbent. The HPLC method developed was validated, determining the accuracy, precision, linearity, decision limit, and detection capability. Both methods were used to monitor raw milk samples of several cows and sheep, obtained from producers in different regions of Greece, for the presence of examined antibiotic residues. Results obtained showed that MIAs could be used effectively and routinely to detect antibiotic residues in several milk types. However, in some cases, spoilage of milk samples revealed that the kits' sensitivity could be strongly affected, whereas this fact does not affect the effectiveness of HPLC-DAD analysis.

Development and validation of liquid chromatographic and UV derivative spectrophotometric methods for the determination of famciclovir in pharmaceutical dosage forms.

PubMed

Srinubabu, Gedela; Sudharani, Batchu; Sridhar, Lade; Rao, Jvln Seshagiri

2006-06-01

A high-performance liquid chromatographic method and a UV derivative spectrophotometric method for the determination of famciclovir, a highly active antiviral agent, in tablets were developed in the present work. The various parameters, such as linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. HPLC was carried out by using the reversed-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic phosphate buffer and methanol (50 : 50; v/v), adjusted to pH 3.05 with orthophosphoric acid. The mobile phase was pumped at a flow rate of 1 ml/min and detection was made at 242 nm with UV dual absorbance detector. The first derivative UV spectrophotometric method was performed at 226.5 nm. Statistical analysis was done by Student's t-test and F-test, which showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and therefore can be used for its Intended purpose.

Simultaneous Determination of Withanolide A and Bacoside A in Spansules by High-Performance Thin-Layer Chromatography

PubMed Central

Shinde, P B; Aragade, P D; Agrawal, M R; Deokate, U A; Khadabadi, S S

2011-01-01

The objective of this work was to develop and validate a simple, rapid, precise, and accurate high performance thin layer chromatography method for simultaneous determination of withanolide A and bacoside A in combined dosage form. The stationary phase used was silica gel G60F254. The mobile phase used was mixture of ethyl acetate: methanol: toluene: water (4:1:1:0.5 v/v/v/v). The detection of spots was carried out at 320 nm using absorbance reflectance mode. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 200 to 800 ng/spot for withanolide A and 50 to 350 ng/spot for bacoside A. The limit of detection and limit of quantification for the withanolide A were found to be 3.05 and 10.06 ng/spot, respectively and for bacoside A 8.3 and 27.39 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed formulation. PMID:22303073

Simultaneous determination of withanolide a and bacoside a in spansules by high-performance thin-layer chromatography.

PubMed

Shinde, P B; Aragade, P D; Agrawal, M R; Deokate, U A; Khadabadi, S S

2011-03-01

The objective of this work was to develop and validate a simple, rapid, precise, and accurate high performance thin layer chromatography method for simultaneous determination of withanolide A and bacoside A in combined dosage form. The stationary phase used was silica gel G60F(254). The mobile phase used was mixture of ethyl acetate: methanol: toluene: water (4:1:1:0.5 v/v/v/v). The detection of spots was carried out at 320 nm using absorbance reflectance mode. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 200 to 800 ng/spot for withanolide A and 50 to 350 ng/spot for bacoside A. The limit of detection and limit of quantification for the withanolide A were found to be 3.05 and 10.06 ng/spot, respectively and for bacoside A 8.3 and 27.39 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed formulation.

A fundamental study of laser-induced breakdown spectroscopy using fiber optics for remote measurements of trace metals. Interim progress report

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

Goode, S.R.; Angel, S.M.

1997-01-01

'The long-term goal of this project is to develop a system to measure the elemental composition of unprepared samples using laser-induced breakdown spectroscopy, LIBS, with a fiber-optic probe. From images shown in this report it is evident that the temporal and spatial behavior of laser-induced plasmas IS a complex process. However, through the use of spectral imaging, optimal conditions can be determined for collecting the atomic emission signal in these plasmas. By tailoring signal collection to the regions of the plasma that contain the highest emission signal with the least amount of background interference both the detection limits and themore » precision of LIBS measurements could be improved. The optimal regions for both gated and possibly non-gated LIBS measurements have been shown to correspond to the inner regions and outer regions, respectively, in an axial plasma. By using this data fiber-optic LIBS probe designs can be optimized for collecting plasma emission at the optimal regions for improved detection limits and precision in a LIBS measurement.'« less

Theoretical limitations of quantification for noncompetitive sandwich immunoassays.

PubMed

Woolley, Christine F; Hayes, Mark A; Mahanti, Prasun; Douglass Gilman, S; Taylor, Tom

2015-11-01

Immunoassays exploit the highly selective interaction between antibodies and antigens to provide a vital method for biomolecule detection at low concentrations. Developers and practitioners of immunoassays have long known that non-specific binding often restricts immunoassay limits of quantification (LOQs). Aside from non-specific binding, most efforts by analytical chemists to reduce the LOQ for these techniques have focused on improving the signal amplification methods and minimizing the limitations of the detection system. However, with detection technology now capable of sensing single-fluorescence molecules, this approach is unlikely to lead to dramatic improvements in the future. Here, fundamental interactions based on the law of mass action are analytically connected to signal generation, replacing the four- and five-parameter fittings commercially used to approximate sigmoidal immunoassay curves and allowing quantitative consideration of non-specific binding and statistical limitations in order to understand the ultimate detection capabilities of immunoassays. The restrictions imposed on limits of quantification by instrumental noise, non-specific binding, and counting statistics are discussed based on equilibrium relations for a sandwich immunoassay. Understanding the maximal capabilities of immunoassays for each of these regimes can greatly assist in the development and evaluation of immunoassay platforms. While many studies suggest that single molecule detection is possible through immunoassay techniques, here, it is demonstrated that the fundamental limit of quantification (precision of 10 % or better) for an immunoassay is approximately 131 molecules and this limit is based on fundamental and unavoidable statistical limitations.

A portable, stable and precise laser differential refractometer

NASA Astrophysics Data System (ADS)

Gong, Xiangjun; Ngai, To; Wu, Chi

2013-11-01

In this work, we present a portable laser differential refractometer with real-time detection and high precision based on the Snell's law and a 2f-2f optical design. The 2f-2f configuration solves a traditional position drifting problem of the laser beam and enhances the signal stability, where a small pinhole is illuminated by the laser light and imaged to the detector by lens placed in the middle between the detector and the pinhole. However, it also leads to a larger dimension of the instrument, limiting its applications and its sensitivity that is proportional to the optical path. Therefore, for a portable device on the basis of the 2f-2f design, a combination of a mirror and a lens was developed to minimize the optical path without affecting the 2f-2f design. Our simple and compact design reaches a resolution of 10-6 refractive index units (RIU). Moreover, the dimension of such a modified differential refractometer is significantly reduced to be portable. Owing to its real-time detection speed and high precision, this newly developed refractometer is particularly attractive when it is used as an independent and ultra-sensitive detector in many research and industrial applications wherein there is a time-dependent concentration change, e.g., the concentration determination, quality control, and study of kinetic processes in solution, including adsorption, sedimentation, and dissolution, to name few but not limited.

Use of experimental design for optimisation of the cold plasma ICP-MS determination of lithium, aluminum and iron in soft drinks and alcoholic beverages.

PubMed

Bianchi, F; Careri, M; Maffini, M; Mangia, A; Mucchino, C

2003-01-01

A sensitive method for the simultaneous determination of (7)Li, (27)Al and (56)Fe by cold plasma ICP-MS was developed and validated. Experimental design was used to investigate the effects of torch position, torch power, lens 2 voltage, and coolant flow. Regression models and desirability functions were applied to find the experimental conditions providing the highest global sensitivity in a multi-elemental analysis. Validation was performed in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity and precision. LODs were 1.4 and 159 ng L(-1) for (7)Li and (56)Fe, respectively; the highest LOD found being that for (27)Al (425 ng L(-1)). Linear ranges of 5 orders of magnitude for Li and 3 orders for Fe were statistically verified for each compound. Precision was evaluated by testing two concentration levels, and good results in terms of both intra-day repeatability and intermediate precision were obtained. RSD values lower than 4.8% at the lowest concentration level were calculated for intra-day repeatability. Commercially available soft drinks and alcoholic beverages contained in different packaging materials (TetraPack, polyethylene terephthalate (PET), commercial cans and glass) were analysed, and all the analytes were detected and quantitated. Copyright 2002 John Wiley & Sons, Ltd.

Use of Protein G Microcolumns in Chromatographic Immunoassays: A Comparison of Competitive Binding Formats

PubMed Central

Pfaunmiller, Erika L.; Anguizola, Jeanethe A.; Milanuk, Mitchell L.; Carter, NaTasha; Hage, David S.

2016-01-01

Affinity microcolumns containing protein G were used as general platforms for creating chromatographic-based competitive binding immunoassays. Human serum albumin (HSA) was used as a model target for this work and HSA tagged with a near infrared fluorescent dye was utilized as the label. The protein G microcolumns were evaluated for use in several assay formats, including both solution-based and column-based competitive binding immunoassays and simultaneous or sequential injection formats. All of these methods were characterized by using the same amounts of labeled HSA and anti-HSA antibodies per sample, as chosen for the analysis of a protein target in the low-to-mid ng/mL range. The results were used to compare these formats in terms of their response, precision, limits of detection, and analysis time. All these methods gave detection limits in the range of 8–19 ng/mL and precisions ranging from ± 5% to ± 10% when using an injection flow rate of 0.10 mL/min. The column-based sequential injection immunoassay provided the best limit of detection and the greatest change in response at low target concentrations, while the solution-based simultaneous injection method had the broadest linear and dynamic ranges. These results provided valuable guidelines that can be employed to develop and extend the use of protein G microcolumns and these competitive binding formats to other protein biomarkers or biological agents of clinical or pharmaceutical interest. PMID:26777776

Quantitative determination of insulin entrapment efficiency in triblock copolymeric nanoparticles by high-performance liquid chromatography.

PubMed

Xu, Xiongliang; Fu, Yao; Hu, Haiyan; Duan, Yourong; Zhang, Zhirong

2006-04-11

A rapid and effective isocratic chromatographic procedure was described in this paper for the determination of insulin entrapment efficiency (EE) in triblock copolymeric nanoparticles using reversed-phase high-performance liquid chromatography (RP-HPLC) with an ultraviolet/visible detector at low flow rate. The method has been developed on a Shimadzu Shim-pack VP-ODS column (150 mm x 4.6 mm, 5 microm, Chiyoda-Ku, Tokyo, Japan) using a mixture of 0.2 M sodium sulfate anhydrous solution adjusted to pH 2.3 with phosphoric acid and acetonitrile (73:27, v/v) as mobile phase at the flow rate of 0.8 ml min(-1) and a 214 nm detection. The method was validated in terms of selectivity, linearity, precision, accuracy, solution stability, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve was linear in the concentration range of 2.0-500.0 microg ml(-1), and the limits of detection and quantitation were 8 and 20 ng, respectively. The mean recovery of insulin from spiked samples, in a concentration range of 8-100 microg ml(-1), was 98.96% (R.S.D.= 2.51%, n = 9). The intra- and inter-assay coefficients of variation were less than 2.24%. The proposed method has the advantages of simple pretreatment, rapid isolation, high specificity and precision, which can be used for direct analysis of insulin in commercially available raw materials, formulations of nanoparticles, and drug release as well as stability studies.

Quantitative determination of methamphetamine in oral fluid by liquid-liquid extraction and gas chromatography/mass spectrometry.

PubMed

Bahmanabadi, L; Akhgari, M; Jokar, F; Sadeghi, H B

2017-02-01

Methamphetamine abuse is one of the most medical and social problems many countries face. In spite of the ban on the use of methamphetamine, it is widely available in Iran's drug black market. There are many analytical methods for the detection of methamphetamine in biological specimen. Oral fluid has become a popular specimen to test for the presence of methamphetamine. The purpose of the present study was to develop a method for the extraction and detection of methamphetamine in oral fluid samples using liquid-liquid extraction (LLE) and gas chromatography/mass spectrometry (GC/MS) methods. An analytical study was designed in that blank and 50 authentic oral fluid samples were collected to be first extracted by LLE and subsequently analysed by GC/MS. The method was fully validated and showed an excellent intra- and inter-assay precision (reflex sympathetic dystrophy ˂ 10%) for external quality control samples. Recovery with LLE methods was 96%. Limit of detection and limit of quantitation were 5 and 15 ng/mL, respectively. The method showed high selectivity, no additional peak due to interfering substances in samples was observed. The introduced method was sensitive, accurate and precise enough for the extraction of methamphetamine from oral fluid samples in forensic toxicology laboratories.

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

Gundlach-Graham, Alexander W.; Dennis, Elise; Ray, Steven J.

An inductively coupled plasma distance-of-flight mass spectrometer (ICP-DOFMS) has been coupled with laser-ablation (LA) sample introduction for the elemental analysis of solids. ICP-DOFMS is well suited for the analysis of laser-generated aerosols because it offers both high-speed mass analysis and simultaneous multi-elemental detection. Here, we evaluate the analytical performance of the LA-ICP-DOFMS instrument, equipped with a microchannel plate-based imaging detector, for the measurement of steady-state LA signals, as well as transient signals produced from single LA events. Steady-state detection limits are 1 mg g1, and absolute single-pulse LA detection limits are 200 fg for uranium; the system is shown capablemore » of performing time-resolved single-pulse LA analysis. By leveraging the benefits of simultaneous multi-elemental detection, we also attain a good shot-to-shot reproducibility of 6% relative standard deviation (RSD) and isotope-ratio precision of 0.3% RSD with a 10 s integration time.« less

A comparison of simultaneous plasma, atomic absorption, and iron colorimetric determinations of major and trace constituents in acid mine waters

USGS Publications Warehouse

Ball, J.W.; Nordstrom, D. Kirk

1994-01-01

Sixty-three water samples collected during June to October 1982 from the Leviathan/Bryant Creek drainage basin were originally analyzed by simultaneous multielement direct-current plasma (DCP) atomic-emission spectrometry, flame atomic-absorption spectrometry, graphite-furnace atomic-absorption spectrometry (GFAAS) (thallium only), ultraviolet-visible spectrometry, and hydride-generation atomic-absorption spectrometry.Determinations were made for the following metallic and semi-metallic constituents: AI, As, B, Ba, Be, Bi, Cd, Ca, Cr, Co, Cu, Fe(11), Fe(total), Li, Pb, Mg, Mn, Mo, Ni, K, Sb, Se, Si, Na, Sr, TI, V, and Zn. These samples were re-analyzed later by simultaneous multielement inductively coupled plasma (ICP) atomic-emission spectrometry and Zeeman-corrected GFAAS to determine the concentrations of many of the same constituents with improved accuracy, precision, and sensitivity. The result of this analysis has been the generation of comparative concentration values for a significant subset of the solute constituents. Many of the more recently determined values replace less-than-detection values for the trace metals; others constitute duplicate analyses for the major constituents. The multiple determinations have yielded a more complete, accurate, and precise set of analytical data. They also have resulted in an opportunity to compare the performance of the plasma-emission instruments operated in their respective simultaneous multielement modes. Flame atomic-absorption spectrometry was judged best for Na and K and hydride-generation atomic-absorption spectrometry was judged best for As because of their lower detection limit and relative freedom from interelement spectral effects. Colorimetric determination using ferrozine as the color agent was judged most accurate, precise, and sensitive for Fe. Cadmium, lead, and vanadium concentrations were too low in this set of samples to enable a determination of whether ICP or DCP is a more suitable technique. Of the remaining elements, Ba, Be, Ca, Cr, Mg, Mn, Sr, and Zn have roughly equivalent accuracy, precision, and detection limit by ICP and DCP. Cobalt and Ni were determined to be better analyzed by ICP, because of lower detection limits; B, Cu, Mo, and Si were determined to be better analyzed by DCP, because of relative freedom from interferences. The determination oral by DCP was far more sensitive, owing to the use of a more sensitive wavelength, compared with the ICP. However, there is a very serious potential interference from a strong Ca emission line near the 396.15 nanometer DCP wavelength. Thus, there is no clear choice between the plasma techniques tested, for the determination oral. The ICP and DCP detection limits are typically between 0.001 and 0.5 milligrams per liter in acid mine waters. For those metals best analyzed by ICP and/or DCP, but below these limits, GFAAS is the method of choice because of its relatively greater sensitivity and specificity. Six of the elements were not determined by DCP, ICP or Zeeman-corrected GFAAS, and are not discussed in this report. These elements are: Bi, Fe(11), Li, Sb, Se, and TI.

Sensitive and selective determination of methylenedioxylated amphetamines by high-performance liquid chromatography with fluorimetric detection.

PubMed

Sadeghipour, F; Veuthey, J L

1997-11-07

A rapid, sensitive and selective liquid chromatographic method with fluorimetric detection was developed for the separation and quantification of four methylenedioxylated amphetamines without interference of other drugs of abuse and common substances found in illicit tablets. The method was validated by examining linearity, precision and accuracy as well as detection and quantification limits. Methylenedioxylated amphetamines were quantified in eight tablets from illicit drug seizures and results were quantitatively compared to HPLC-UV analyses. To demonstrate the better sensitivity of the fluorimetric detection, methylenedioxylated amphetamines were analyzed in serum after a liquid-liquid extraction procedure and results were also compared to HPLC-UV analyses.

Development and validation of a reversed-phase HPLC method for simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet dosage form.

PubMed

Shaikh, K A; Patil, S D; Devkhile, A B

2008-12-15

A simple, precise and accurate reversed-phase liquid chromatographic method has been developed for the simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet formulations. The chromatographic separation was achieved on a Xterra RP18 (250 mm x 4.6 mm, 5 microm) analytical column. A Mixture of acetonitrile-dipotassium phosphate (30 mM) (50:50, v/v) (pH 9.0) was used as the mobile phase, at a flow rate of 1.7 ml/min and detector wavelength at 215 nm. The retention time of ambroxol and azithromycin was found to be 5.0 and 11.5 min, respectively. The validation of the proposed method was carried out for specificity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness. The linear dynamic ranges were from 30-180 to 250-1500 microg/ml for ambroxol hydrochloride and azithromycin, respectively. The percentage recovery obtained for ambroxol hydrochloride and azithromycin were 99.40 and 99.90%, respectively. Limit of detection and quantification for azithromycin were 0.8 and 2.3 microg/ml, for ambroxol hydrochloride 0.004 and 0.01 microg/ml, respectively. The developed method can be used for routine quality control analysis of titled drugs in combination in tablet formulation.

[Detection of rifampicin concentration in cerebrospinal fluid by online enrichment and restricted-access media coupled with high-performance liquid chromatography].

PubMed

Yang, Xiaoping; Zhang, Xiaohui; Huang, Yanping; Wang, Rong; Xia, Hua; Li, Wenbin; Guo, YouMin

2015-11-01

To establish a method for detecting rifampicin in human cerebrospinal fluid (CSF) with restricted access media coupled with high-performance liquid chromatography that allows online direct sample injection and enrichment. We used the column of restricted access media as the pre-treatment column and a C18 column as the analytical column. The mobile phase of pre-treatment column was water-methanol (95:5,V/V) and the flow rate was 1 mL/min; the mobile phase of the analytical column was methanol-acetonitrile-10 mmol/L ammonuium acetate (volume ratio of 60:5:35). The detection wavelength was 254 nm and the column temperature was set at 25 degrees celsius;. For an injection volume of 100 µL, the peak area of rifampicin was 5.33 times that for an injection volume of 20 µL, and the limit of detection was effectively improved. The calibration curve showed an excellent linear relationship (r=0.9997) between rifampicin concentrations and peak areas within the concentration range of 0.25 to 8 µg/mL in CSF. The limits of detection and quantification was 0.07 µg/mL and 0.25 µg/mL, respecetively, with intra-day and inter-day assay precisions and relative standard deviation (RSD%) all below 5%. The recoveries of rifampicin at 3 blank spiked levels (low, medium, and high) ranged from 87.69% to 102.11%. In patients taking oral rifampicin at the dose of 10 mg/kg, the average rifampicin concentration was 0.29 in the CSF at 2 h after medication. The method we established is simple and fast for detecting rifampicin in CSF and allows direct online injection and enrichment with good detection precisions and accuracies.

Bringing mirrors to rest: grating concepts for ultra-precise interferometry

NASA Astrophysics Data System (ADS)

Kroker, Stefanie; Kley, Ernst-Bernhard; Tünnermann, Andreas

2015-02-01

Experiments in the field of high precision metrology such as the detection of gravitational waves are crucially limited by the thermal fluctuations of the optical components. In this contribution we present the current state of knowledge of high contrast gratings (HCGs) as low-noise elements for gravitational wave interferometers. We discuss how the properties of HCGs can be tailored such that beside highly reflective mirrors also diffractive beam splitters can be realized. Further, we show the impact of such gratings on the sensitivity of future gravitational wave detectors which can pave the way for the new field of gravitational wave astronomy.

Detectability Thresholds and Optimal Algorithms for Community Structure in Dynamic Networks

NASA Astrophysics Data System (ADS)

Ghasemian, Amir; Zhang, Pan; Clauset, Aaron; Moore, Cristopher; Peel, Leto

2016-07-01

The detection of communities within a dynamic network is a common means for obtaining a coarse-grained view of a complex system and for investigating its underlying processes. While a number of methods have been proposed in the machine learning and physics literature, we lack a theoretical analysis of their strengths and weaknesses, or of the ultimate limits on when communities can be detected. Here, we study the fundamental limits of detecting community structure in dynamic networks. Specifically, we analyze the limits of detectability for a dynamic stochastic block model where nodes change their community memberships over time, but where edges are generated independently at each time step. Using the cavity method, we derive a precise detectability threshold as a function of the rate of change and the strength of the communities. Below this sharp threshold, we claim that no efficient algorithm can identify the communities better than chance. We then give two algorithms that are optimal in the sense that they succeed all the way down to this threshold. The first uses belief propagation, which gives asymptotically optimal accuracy, and the second is a fast spectral clustering algorithm, based on linearizing the belief propagation equations. These results extend our understanding of the limits of community detection in an important direction, and introduce new mathematical tools for similar extensions to networks with other types of auxiliary information.

Detection of small orientation changes and the precision of visual working memory.

PubMed

Salmela, Viljami R; Saarinen, Jussi

2013-01-14

We investigated the precision of orientation representations with two tasks, change detection and recall. Previously change detection has been measured only with relatively large orientation changes compared to psychophysical thresholds. In the first experiment, we measured the observers' ability (d') to detect small changes in orientation (5-30°) with 1-4 Gabor items. With one item even a 10° change was well detected (average d'=2.5). As the amount of change increased to 30°, the d' increased to 5.2. When the number of items was increased, the d's gradually decreased. In the second experiment, we used a recall task and the observers adjusted the orientation of a probe Gabor to match the orientation of a Gabor held in the memory. The standard deviation (s.d.) of errors was calculated from the Gaussian distribution fitted to the data. As the number of items increased from 1 to 6, the s.d. increased from 8.6° to 19.6°. Even with six items, the observers did not make any random adjustments. The results show a square root relation between the d'/s.d. and the number of items. The d' in change detection is directly proportional to the square root of (1/n) and the orientation change. The increase of the s.d. in recall task is inversely proportional to square root of (1/n). The results suggest that limited resources and precision of representations, without additional assumptions, determine the memory performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multi-resolution Gabor wavelet feature extraction for needle detection in 3D ultrasound

NASA Astrophysics Data System (ADS)

Pourtaherian, Arash; Zinger, Svitlana; Mihajlovic, Nenad; de With, Peter H. N.; Huang, Jinfeng; Ng, Gary C.; Korsten, Hendrikus H. M.

2015-12-01

Ultrasound imaging is employed for needle guidance in various minimally invasive procedures such as biopsy guidance, regional anesthesia and brachytherapy. Unfortunately, a needle guidance using 2D ultrasound is very challenging, due to a poor needle visibility and a limited field of view. Nowadays, 3D ultrasound systems are available and more widely used. Consequently, with an appropriate 3D image-based needle detection technique, needle guidance and interventions may significantly be improved and simplified. In this paper, we present a multi-resolution Gabor transformation for an automated and reliable extraction of the needle-like structures in a 3D ultrasound volume. We study and identify the best combination of the Gabor wavelet frequencies. High precision in detecting the needle voxels leads to a robust and accurate localization of the needle for the intervention support. Evaluation in several ex-vivo cases shows that the multi-resolution analysis significantly improves the precision of the needle voxel detection from 0.23 to 0.32 at a high recall rate of 0.75 (gain 40%), where a better robustness and confidence were confirmed in the practical experiments.

[Assessment of lymph node metastasis in gastric cancer: status quo, recent advances and new perspectives].

PubMed

Tu, Min; Zhu, Zhen-shu; Shi, Lin-sen; Jiang, Xi-qun; Wang, Hao; Guan, Wen-xian

2012-02-01

The precondition of accurate gastric cancer surgery is precise assessment of lymph node metastasis. To date, no imaging modality achieves both high sensitivity and high specificity in detecting lymph node metastasis in gastric cancer. Intraoperative sentinel node tracing and biopsy are the most popular method to identify the localization of tumor cell, but is limited to early gastric cancer. Nano-composite materials, designed for tumor imaging and tracing, show us a newly emerging domain for tumor detection in gastric cancer. The function of these nano-composite materials to detect lymph node metastasis in gastric cancer relies on the effective backflow of lymph system. However, the lymph vessels can be obstructed by tumor cells in advanced gastric cancer, which may restrain the application of these nanoparticles. Therefore, more methods to detect lymph node metastasis in gastric cancer should be explored. This review summarizes the characteristic of the targeted nanosphere. Based on the reported studies, a novel idea is conceived that targeted multifunctional nanosphere may be a potential method to achieve precise assessment of lymph node metastasis in gastric cancer.

Single photon detection and timing in the Lunar Laser Ranging Experiment.

NASA Technical Reports Server (NTRS)

Poultney, S. K.

1972-01-01

The goals of the Lunar Laser Ranging Experiment lead to the need for the measurement of a 2.5 sec time interval to an accuracy of a nanosecond or better. The systems analysis which included practical retroreflector arrays, available laser systems, and large telescopes led to the necessity of single photon detection. Operation under all background illumination conditions required auxiliary range gates and extremely narrow spectral and spatial filters in addition to the effective gate provided by the time resolution. Nanosecond timing precision at relatively high detection efficiency was obtained using the RCA C31000F photomultiplier and Ortec 270 constant fraction of pulse-height timing discriminator. The timing accuracy over the 2.5 sec interval was obtained using a digital interval with analog vernier ends. Both precision and accuracy are currently checked internally using a triggerable, nanosecond light pulser. Future measurements using sub-nanosecond laser pulses will be limited by the time resolution of single photon detectors.

Determination of Mercury in Milk by Cold Vapor Atomic Fluorescence: A Green Analytical Chemistry Laboratory Experiment

ERIC Educational Resources Information Center

Armenta, Sergio; de la Guardia, Miguel

2011-01-01

Green analytical chemistry principles were introduced to undergraduate students in a laboratory experiment focused on determining the mercury concentration in cow and goat milk. In addition to traditional goals, such as accuracy, precision, sensitivity, and limits of detection in method selection and development, attention was paid to the…

Ultra trace determination of 31 pesticides in water samples by direct injection-rapid resolution liquid chromatography-electrospray tandem mass spectrometry.

PubMed

Díaz, Laura; Llorca-Pórcel, Julio; Valor, Ignacio

2008-08-22

A liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method for the detection of pesticides in tap and treated wastewater was developed and validated according to the ISO/IEC 17025:1999. Key features of this method include direct injection of 100 microL of sample, an 11 min separation by means of a rapid resolution liquid chromatography system with a 4.6 mm x 50 mm, 1.8 microm particle size reverse phase column and detection by electrospray ionization (ESI) MS-MS. The limits of detection were below 15 ng L(-1) and correlation coefficients for the calibration curves in the range of 30-2000 ng L(-1) were higher than 0.99. Precision was always below 20% and accuracy was confirmed by external evaluation. The main advantages of this method are direct injection of sample without preparative procedures and low limits of detection that fulfill the requirements established by the current European regulations governing pesticide detection.

Advances in Multicollector ICPMS for precise and accurate isotope ratio measurements of Uranium isotopes

NASA Astrophysics Data System (ADS)

Bouman, C.; Lloyd, N. S.; Schwieters, J.

2011-12-01

The accurate and precise determination of uranium isotopes is challenging, because of the large dynamic range posed by the U isotope abundances and the limited available sample material. Various mass spectrometric techniques are used for the measurement of U isotopes, where TIMS is the most accepted and accurate one. Multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) can offer higher productivity compared to TIMS, but is traditionally limited by low efficiency of sample utilisation. This contribution will discuss progress in MC-ICPMS for detecting 234U, 235U, 236U and 238U in various uranium reference materials from IRMM and NBL. The Thermo Scientific NEPTUNE Plus with Jet Interface offers a modified dry plasma ICP interface using a large interface pump combined with a special set of sample and skimmer cones giving ultimate sensitivity for all elements across the mass range. For uranium, an ion yield of > 3 % was reported previously [1]. The NEPTUNE Plus also offers Multi Ion Counting using discrete dynode electron multipliers as well as two high abundance-sensitivity filters to discriminate against peak tailing effects on 234U and 236U originating from the major uranium beams. These improvements in sensitivity and dynamic range allow accurate measurements of 234U, 235U and 236U abundances on very small samples and at low concentration. In our approach, minor U isotopes 234U and 236U were detected on ion counters with high abundance sensitivity filters, whereas 235U and 238U were detected on Faraday Cups using a high gain current amplifier (10e12 Ohm) for 235U. Precisions and accuracies for 234U and 236U were down to ~1%. For 235U, subpermil levels were reached.

Automation of ⁹⁹Tc extraction by LOV prior ICP-MS detection: application to environmental samples.

PubMed

Rodríguez, Rogelio; Leal, Luz; Miranda, Silvia; Ferrer, Laura; Avivar, Jessica; García, Ariel; Cerdà, Víctor

2015-02-01

A new, fast, automated and inexpensive sample pre-treatment method for (99)Tc determination by inductively coupled plasma-mass spectrometry (ICP-MS) detection is presented. The miniaturized approach is based on a lab-on-valve (LOV) system, allowing automatic separation and preconcentration of (99)Tc. Selectivity is provided by the solid phase extraction system used (TEVA resin) which retains selectively pertechnetate ion in diluted nitric acid solution. The proposed system has some advantages such as minimization of sample handling, reduction of reagents volume, improvement of intermediate precision and sample throughput, offering a significant decrease of both time and cost per analysis in comparison to other flow techniques and batch methods. The proposed LOV system has been successfully applied to different samples of environmental interest (water and soil) with satisfactory recoveries, between 94% and 98%. The detection limit (LOD) of the developed method is 0.005 ng. The high durability of the resin and its low amount (32 mg), its good intermediate precision (RSD 3.8%) and repeatability (RSD 2%) and its high extraction frequency (up to 5 h(-1)) makes this method an inexpensive, high precision and fast tool for monitoring (99)Tc in environmental samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Scheme for efficient extraction of low-frequency signal beyond the quantum limit by frequency-shift detection.

PubMed

Yang, R G; Zhang, J; Zhai, Z H; Zhai, S Q; Liu, K; Gao, J R

2015-08-10

Low-frequency (Hz~kHz) squeezing is very important in many schemes of quantum precision measurement. But it is more difficult than that at megahertz-frequency because of the introduction of laser low-frequency technical noise. In this paper, we propose a scheme to obtain a low-frequency signal beyond the quantum limit from the frequency comb in a non-degenerate frequency and degenerate polarization optical parametric amplifier (NOPA) operating below threshold with type I phase matching by frequency-shift detection. Low-frequency squeezing immune to laser technical noise is obtained by a detection system with a local beam of two-frequency intense laser. Furthermore, the low-frequency squeezing can be used for phase measurement in Mach-Zehnder interferometer, and the signal-to-noise ratio (SNR) can be enhanced greatly.

A simple high performance liquid chromatography method for analyzing paraquat in soil solution samples.

PubMed

Ouyang, Ying; Mansell, Robert S; Nkedi-Kizza, Peter

2004-01-01

A high performance liquid chromatography (HPLC) method with UV detection was developed to analyze paraquat (1,1'-dimethyl-4,4'-dipyridinium dichloride) herbicide content in soil solution samples. The analytical method was compared with the liquid scintillation counting (LSC) method using 14C-paraquat. Agreement obtained between the two methods was reasonable. However, the detection limit for paraquat analysis was 0.5 mg L(-1) by the HPLC method and 0.05 mg L(-1) by the LSC method. The LSC method was, therefore, 10 times more precise than the HPLC method for solution concentrations less than 1 mg L(-1). In spite of the high detection limit, the UC (nonradioactive) HPLC method provides an inexpensive and environmentally safe means for determining paraquat concentration in soil solution compared with the 14C-LSC method.

A novel stability-indicating UPLC method development and validation for the determination of seven impurities in various diclofenac pharmaceutical dosage forms.

PubMed

Azougagh, M; Elkarbane, M; Bakhous, K; Issmaili, S; Skalli, A; Iben Moussad, S; Benaji, B

2016-09-01

An innovative simple, fast, precise and accurate ultra-high performance liquid chromatography (UPLC) method was developed for the determination of diclofenac (Dic) along with its impurities including the new dimer impurity in various pharmaceutical dosage forms. An Acquity HSS T3 (C18, 100×2.1mm, 1.8μm) column in gradient mode was used with mobile phase comprising of phosphoric acid, which has a pH value of 2.3 and methanol. The flow rate and the injection volume were set at 0.35ml·min(-1) and 1μl, respectively, and the UV detection was carried out at 254nm by using photodiode array detector. Dic was subjected to stress conditions from acid, base, hydrolytic, thermal, oxidative and photolytic degradation. The new developed method was successfully validated in accordance to the International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantitation, precision, linearity, accuracy and robustness. The degradation products were well resolved from main peak and its seven impurities, proving the specificity power of the method. The method showed good linearity with consistent recoveries for Dic content and its impurities. The relative percentage of standard deviation obtained for the repeatability and intermediate precision experiments was less than 3% and LOQ was less than 0.5μg·ml(-1) for all compounds. The new proposed method was found to be accurate, precise, specific, linear and robust. In addition, the method was successfully applied for the assay determination of Dic and its impurities in the several pharmaceutical dosage forms. Copyright © 2016 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

Ion chromatography for the precise analysis of chloride and sodium in sweat for the diagnosis of cystic fibrosis.

PubMed

Doorn, J; Storteboom, T T R; Mulder, A M; de Jong, W H A; Rottier, B L; Kema, I P

2015-07-01

Measurement of chloride in sweat is an essential part of the diagnostic algorithm for cystic fibrosis. The lack in sensitivity and reproducibility of current methods led us to develop an ion chromatography/high-performance liquid chromatography (IC/HPLC) method, suitable for the analysis of both chloride and sodium in small volumes of sweat. Precision, linearity and limit of detection of an in-house developed IC/HPLC method were established. Method comparison between the newly developed IC/HPLC method and the traditional Chlorocounter was performed, and trueness was determined using Passing Bablok method comparison with external quality assurance material (Royal College of Pathologists of Australasia). Precision and linearity fulfill criteria as established by UK guidelines are comparable with inductively coupled plasma-mass spectrometry methods. Passing Bablok analysis demonstrated excellent correlation between IC/HPLC measurements and external quality assessment target values, for both chloride and sodium. With a limit of quantitation of 0.95 mmol/L, our method is suitable for the analysis of small amounts of sweat and can thus be used in combination with the Macroduct collection system. Although a chromatographic application results in a somewhat more expensive test compared to a Chlorocounter test, more accurate measurements are achieved. In addition, simultaneous measurements of sodium concentrations will result in better detection of false positives, less test repeating and thus faster and more accurate and effective diagnosis. The described IC/HPLC method, therefore, provides a precise, relatively cheap and easy-to-handle application for the analysis of both chloride and sodium in sweat. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Fast fMRI can detect oscillatory neural activity in humans.

PubMed

Lewis, Laura D; Setsompop, Kawin; Rosen, Bruce R; Polimeni, Jonathan R

2016-10-25

Oscillatory neural dynamics play an important role in the coordination of large-scale brain networks. High-level cognitive processes depend on dynamics evolving over hundreds of milliseconds, so measuring neural activity in this frequency range is important for cognitive neuroscience. However, current noninvasive neuroimaging methods are not able to precisely localize oscillatory neural activity above 0.2 Hz. Electroencephalography and magnetoencephalography have limited spatial resolution, whereas fMRI has limited temporal resolution because it measures vascular responses rather than directly recording neural activity. We hypothesized that the recent development of fast fMRI techniques, combined with the extra sensitivity afforded by ultra-high-field systems, could enable precise localization of neural oscillations. We tested whether fMRI can detect neural oscillations using human visual cortex as a model system. We detected small oscillatory fMRI signals in response to stimuli oscillating at up to 0.75 Hz within single scan sessions, and these responses were an order of magnitude larger than predicted by canonical linear models. Simultaneous EEG-fMRI and simulations based on a biophysical model of the hemodynamic response to neuronal activity suggested that the blood oxygen level-dependent response becomes faster for rapidly varying stimuli, enabling the detection of higher frequencies than expected. Accounting for phase delays across voxels further improved detection, demonstrating that identifying vascular delays will be of increasing importance with higher-frequency activity. These results challenge the assumption that the hemodynamic response is slow, and demonstrate that fMRI has the potential to map neural oscillations directly throughout the brain.

Sensitivity and accuracy of high-throughput metabarcoding methods for early detection of invasive fish species

NASA Astrophysics Data System (ADS)

Hatzenbuhler, Chelsea; Kelly, John R.; Martinson, John; Okum, Sara; Pilgrim, Erik

2017-04-01

High-throughput DNA metabarcoding has gained recognition as a potentially powerful tool for biomonitoring, including early detection of aquatic invasive species (AIS). DNA based techniques are advancing, but our understanding of the limits to detection for metabarcoding complex samples is inadequate. For detecting AIS at an early stage of invasion when the species is rare, accuracy at low detection limits is key. To evaluate the utility of metabarcoding in future fish community monitoring programs, we conducted several experiments to determine the sensitivity and accuracy of routine metabarcoding methods. Experimental mixes used larval fish tissue from multiple “common” species spiked with varying proportions of tissue from an additional “rare” species. Pyrosequencing of genetic marker, COI (cytochrome c oxidase subunit I) and subsequent sequence data analysis provided experimental evidence of low-level detection of the target “rare” species at biomass percentages as low as 0.02% of total sample biomass. Limits to detection varied interspecifically and were susceptible to amplification bias. Moreover, results showed some data processing methods can skew sequence-based biodiversity measurements from corresponding relative biomass abundances and increase false absences. We suggest caution in interpreting presence/absence and relative abundance in larval fish assemblages until metabarcoding methods are optimized for accuracy and precision.

Cosmic ray measurements with LOPES: Status and recent results

NASA Astrophysics Data System (ADS)

Schröder, F. G.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.

2013-05-01

LOPES is a digital antenna array at the Karlsruhe Institute of Technology, Germany, for cosmic-ray air-shower measurements. Triggered by the co-located KASCADE-Grande air-shower array, LOPES detects the radio emission of air showers via digital radio interferometry. We summarize the status of LOPES and recent results. In particular, we present an update on the reconstruction of the primary-particle properties based on almost 500 events above 100PeV. With LOPES, the arrival direction can be reconstructed with a precision of at least 0.65°, and the energy with a precision of at least 20%, which, however, does not include systematic uncertainties on the absolute energy scale. For many particle and astrophysics questions the reconstruction of the atmospheric depth of the shower maximum, Xmax, is important, since it yields information on the type of the primary particle and its interaction with the atmosphere. Recently, we found experimental evidence that the slope of the radio lateral distribution is indeed sensitive to the longitudinal development of the air shower, but unfortunately, the Xmax precision at LOPES is limited by the high level of anthropogenic radio background. Nevertheless, the developed methods can be transferred to next generation experiments with lower background, which should provide an Xmax precision competitive to other detection technologies.

Limits of detection and decision. Part 3

NASA Astrophysics Data System (ADS)

Voigtman, E.

2008-02-01

It has been shown that the MARLAP (Multi-Agency Radiological Laboratory Analytical Protocols) for estimating the Currie detection limit, which is based on 'critical values of the non-centrality parameter of the non-central t distribution', is intrinsically biased, even if no calibration curve or regression is used. This completed the refutation of the method, begun in Part 2. With the field cleared of obstructions, the true theory underlying Currie's limits of decision, detection and quantification, as they apply in a simple linear chemical measurement system (CMS) having heteroscedastic, Gaussian measurement noise and using weighted least squares (WLS) processing, was then derived. Extensive Monte Carlo simulations were performed, on 900 million independent calibration curves, for linear, "hockey stick" and quadratic noise precision models (NPMs). With errorless NPM parameters, all the simulation results were found to be in excellent agreement with the derived theoretical expressions. Even with as much as 30% noise on all of the relevant NPM parameters, the worst absolute errors in rates of false positives and false negatives, was only 0.3%.

Determination of Minor and Trace Metals in Aluminum and Aluminum Alloys by ICP-AES; Evaluation of the Uncertainty and Limit of Quantitation from Interlaboratory Testing.

PubMed

Uemoto, Michihisa; Makino, Masanori; Ota, Yuji; Sakaguchi, Hiromi; Shimizu, Yukari; Sato, Kazuhiro

2018-01-01

Minor and trace metals in aluminum and aluminum alloys have been determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) as an interlaboratory testing toward standardization. The trueness of the measured data was successfully investigated to improve the analytical protocols, using certified reference materials of aluminum. Their precision could also be evaluated, feasible to estimate the uncertainties separately. The accuracy (trueness and precision) of the data were finally in good agreement with the certified values and assigned uncertainties. Repeated measurements of aluminum solutions with different concentrations of the analytes revealed the relative standard deviations of the measurements with concentrations, thus enabling their limits of quantitation. They differed separately and also showed slightly higher values with an aluminum matrix than those without one. In addition, the upper limit of the detectable concentration of silicon with simple acid digestion was estimated to be 0.03 % in the mass fraction.

Solid phase extraction with high polarity Carb/PSA as composite fillers prior to UPLC-MS/MS to determine six bisphenols and alkylphenols in trace level hotpot seasoning.

PubMed

Dong, Hao; Zeng, Xiaofang; Bai, Weidong

2018-08-30

The present study reports an ultra high-performance liquid chromatography tandem mass spectrometry method for the simultaneous determination of six bisphenols (bisphenol A, bisphenol B and bisphenol F) and alkylphenols (4-nonylphenol, 4-n-nonylphenol and octylphenol) in hotpot seasoning. Samples were dispersed in n-hexane after addition of internal standards bisphenol A-d 4 and 4-n-nonylphenol-d 4 . Sample solutions were then centrifuged, and the supernatants purified using solid phase extraction with high polarity Carb/PSA composite fillers. Six target analytes were separated on a Waters ACQUITY BEH C18 column by gradient elution with methanol and 0.05% ammonium hydroxide in water as the mobile phase, and determined under multiple reactions monitoring mode. The limits of detection and quantitation, matrix effect, recovery and precision of the method were investigated. Results were linear in the concentration range 0.1-250 µg/L for all compounds of interest, with R 2  > 0.9950. Limits of detection were in the range 0.1-0.4 μg/kg, and limits of quantitation were between 0.5 μg/kg and 1.0 μg/kg. The mean recoveries for negative samples at three spiked concentrations were in the range 87.9%-102.4%, and the intra-day precision and inter-day precision were in the ranges 2.1-8.2% and 4.8-11.2%, respectively. This method is accurate and sensitive, and had good clean-up characteristics, which might apply to screening and quantitation of target bisphenols and alkylphenols in hotpot seasoning. Copyright © 2018 Elsevier Ltd. All rights reserved.

Integrated multi-ISE arrays with improved sensitivity, accuracy and precision

NASA Astrophysics Data System (ADS)

Wang, Chunling; Yuan, Hongyan; Duan, Zhijuan; Xiao, Dan

2017-03-01

Increasing use of ion-selective electrodes (ISEs) in the biological and environmental fields has generated demand for high-sensitivity ISEs. However, improving the sensitivities of ISEs remains a challenge because of the limit of the Nernstian slope (59.2/n mV). Here, we present a universal ion detection method using an electronic integrated multi-electrode system (EIMES) that bypasses the Nernstian slope limit of 59.2/n mV, thereby enabling substantial enhancement of the sensitivity of ISEs. The results reveal that the response slope is greatly increased from 57.2 to 1711.3 mV, 57.3 to 564.7 mV and 57.7 to 576.2 mV by electronic integrated 30 Cl- electrodes, 10 F- electrodes and 10 glass pH electrodes, respectively. Thus, a tiny change in the ion concentration can be monitored, and correspondingly, the accuracy and precision are substantially improved. The EIMES is suited for all types of potentiometric sensors and may pave the way for monitoring of various ions with high accuracy and precision because of its high sensitivity.

DISENTANGLING CONFUSED STARS AT THE GALACTIC CENTER WITH LONG-BASELINE INFRARED INTERFEROMETRY

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

Stone, Jordan M.; Eisner, J. A.; Monnier, J. D.

2012-08-01

We present simulations of Keck Interferometer ASTRA and VLTI GRAVITY observations of mock star fields in orbit within {approx}50 mas of Sgr A*. Dual-field phase referencing techniques, as implemented on ASTRA and planned for GRAVITY, will provide the sensitivity to observe Sgr A* with long-baseline infrared interferometers. Our results show an improvement in the confusion noise limit over current astrometric surveys, opening a window to study stellar sources in the region. Since the Keck Interferometer has only a single baseline, the improvement in the confusion limit depends on source position angles. The GRAVITY instrument will yield a more compact andmore » symmetric point-spread function, providing an improvement in confusion noise which will not depend as strongly on position angle. Our Keck results show the ability to characterize the star field as containing zero, few, or many bright stellar sources. We are also able to detect and track a source down to m{sub K} {approx} 18 through the least confused regions of our field of view at a precision of {approx}200 {mu}as along the baseline direction. This level of precision improves with source brightness. Our GRAVITY results show the potential to detect and track multiple sources in the field. GRAVITY will perform {approx}10 {mu}as astrometry on an m{sub K} = 16.3 source and {approx}200 {mu}as astrometry on an m{sub K} = 18.8 source in 6 hr of monitoring a crowded field. Monitoring the orbits of several stars will provide the ability to distinguish between multiple post-Newtonian orbital effects, including those due to an extended mass distribution around Sgr A* and to low-order general relativistic effects. ASTRA and GRAVITY both have the potential to detect and monitor sources very close to Sgr A*. Early characterizations of the field by ASTRA, including the possibility of a precise source detection, could provide valuable information for future GRAVITY implementation and observation.« less

Design of the NDUV detection circuit for the NO concentration of the vehicle exhaust emissions

NASA Astrophysics Data System (ADS)

Zhang, Kai; Zhang, Yujun; He, Ying; You, Kun; Gao, Yanwei; Chen, Chen; Liu, Guohua; He, Chungui; Lu, Yibing; Liu, Wenqing

2016-10-01

With the increasing number of vehicles, the harm from NO to the environment becomes more and more prominent. So the monitoring of the NO concentration of the vehicle exhaust emissions is very important to assess the emission levels. In this paper, the NO detection system designing for vehicle exhaust emissions based on the non-dispersive ultraviolet principle (NDUV) has been researched. The technical indexes of the two-way modulation UV signal detection circuit are discussed in detail. And then a precision detection circuit is designed, which is composed of a trans-impedance amplifier and a lock-in amplifier, with which the output of the UV photoelectric detector can be amplified to a suitable voltage range, and the DC noise of the pre-stage amplifier is effectively removed by the lock-in amplifier. An experimental system was set up to test the designed circuit. To ensure the consistency of the two channels, the method of exchange calibration was adopted in the test. It's drawn that the designed circuit is of high SNR, measuring accuracy and a large dynamic range from the test results. The NO concentration detection limit of vehicle emissions can reach 1ppm, and the detection precision is +/-15ppm.

Automated and sensitive method for the determination of formoterol in human plasma by high-performance liquid chromatography and electrochemical detection.

PubMed

Campestrini, J; Lecaillon, J B; Godbillon, J

1997-12-19

An automated high-performance liquid chromatography (HPLC) method for the determination of formoterol in human plasma with improved sensitivity has been developed and validated. Formoterol and CGP 47086, the internal standard, were extracted from plasma (1 ml) using a cation-exchange solid-phase extraction (SPE) cartridge. The compounds were eluted with pH 6 buffer solution-methanol (70:30, v/v) and the eluate was further diluted with water. An aliquot of the extract solution was injected and analyzed by HPLC. The extraction, dilution, injection and chromatographic analysis were combined and automated using the automate (ASPEC) system. The chromatographic separations were achieved on a 5 microm, Hypersil ODS analytical column (200 mm x 3 mm I.D.), using (pH 6 phosphate buffer, 0.035 M + 20 mg/l EDTA)-MeOH-CH3CN (70:25:5, v/v/v) as the mobile phase at a flow-rate of 0.4 ml/min. The analytes were detected with electrochemical detection at an operating potential of +0.63 V. Intra-day accuracy and precision were assessed from the relative recoveries of calibration/quality control plasma samples in the concentration range of 7.14 to 238 pmol/l of formoterol base. The accuracy over the entire concentration range varied from 81 to 105%, and the precision (C.V.) ranged from 3 to 14%. Inter-day accuracy and precision were assessed in the concentration range of 11.9 to 238 pmol/l of formoterol base in plasma. The accuracy over the entire concentration range varied from 98 to 109%, and precision ranged from 8 to 19%. At the limit of quantitation (LOQ) of 11.9 pmol/l for inter-day measurements, the recovery value was 109% and C.V. was 19%. As shown from intra-day accuracy and precision results, favorable conditions (a newly used column, a newly washed detector cell and moderate residual cell current level) allowed us to reach a LOQ of 7.14 pmol/l of formoterol base (3 pg/ml of formoterol fumarate dihydrate). Improvement of the limit of detection by a factor of about 10 was reached as compared to the previously described methods. The method has been applied for quantifying formoterol in plasma after 120 microg drug inhalation to volunteers. Formoterol was still measurable at 24 h post-dosing in most subjects and a slow elimination of formoterol from plasma beyond 6-8 h after inhalation was demonstrated for the first time thanks to the sensitivity of the method.

A portable, stable and precise laser differential refractometer

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

Gong, Xiangjun, E-mail: xjgong@cuhk.edu.hk, E-mail: chiwu@cuhk.edu.hk; Ngai, To; Wu, Chi, E-mail: xjgong@cuhk.edu.hk, E-mail: chiwu@cuhk.edu.hk

In this work, we present a portable laser differential refractometer with real-time detection and high precision based on the Snell's law and a 2f-2f optical design. The 2f-2f configuration solves a traditional position drifting problem of the laser beam and enhances the signal stability, where a small pinhole is illuminated by the laser light and imaged to the detector by lens placed in the middle between the detector and the pinhole. However, it also leads to a larger dimension of the instrument, limiting its applications and its sensitivity that is proportional to the optical path. Therefore, for a portable devicemore » on the basis of the 2f-2f design, a combination of a mirror and a lens was developed to minimize the optical path without affecting the 2f-2f design. Our simple and compact design reaches a resolution of 10{sup −6} refractive index units (RIU). Moreover, the dimension of such a modified differential refractometer is significantly reduced to be portable. Owing to its real-time detection speed and high precision, this newly developed refractometer is particularly attractive when it is used as an independent and ultra-sensitive detector in many research and industrial applications wherein there is a time-dependent concentration change, e.g., the concentration determination, quality control, and study of kinetic processes in solution, including adsorption, sedimentation, and dissolution, to name few but not limited.« less

RP-HPLC method development and validation for simultaneous estimation of atorvastatin calcium and pioglitazone hydrochloride in pharmaceutical dosage form.

PubMed

Peraman, Ramalingam; Mallikarjuna, Sasikala; Ammineni, Pravalika; Kondreddy, Vinod kumar

2014-10-01

A simple, selective, rapid, precise and economical reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for simultaneous estimation of atorvastatin calcium (ATV) and pioglitazone hydrochloride (PIO) from pharmaceutical formulation. The method is carried out on a C8 (25 cm × 4.6 mm i.d., 5 μm) column with a mobile phase consisting of acetonitrile (ACN):water (pH adjusted to 6.2 using o-phosphoric acid) in the ratio of 45:55 (v/v). The retention time of ATV and PIO is 4.1 and 8.1 min, respectively, with the flow rate of 1 mL/min with diode array detector detection at 232 nm. The linear regression analysis data from the linearity plot showed good linear relationship with a correlation coefficient (R(2)) value for ATV and PIO of 0.9998 and 0.9997 in the concentration range of 10-80 µg mL(-1), respectively. The relative standard deviation for intraday precision has been found to be <2.0%. The method is validated according to the ICH guidelines. The developed method is validated in terms of specificity, selectivity, accuracy, precision, linearity, limit of detection, limit of quantitation and solution stability. The proposed method can be used for simultaneous estimation of these drugs in marketed dosage forms. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A rapid method for the simultaneous determination of 25 anti-hypertensive compounds in dietary supplements using ultra-high-pressure liquid chromatography.

PubMed

Heo, Seok; Yoo, Geum Joo; Choi, Ji Yeon; Park, Hyoung Joon; Park, Sung-Kwan; Baek, Sun Young

2016-11-01

A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20-1.00 and 0.60-3.00 μg ml -1 , respectively, while those of liquid samples were 0.30-1.20 and 0.90-3.60 μg ml -1 , respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15-6.48% and 0.28-8.67%, respectively. The intra- and inter-day accuracies were 82.25-111.42% and 80.70-115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market.

Laser microprobe and resonant laser ablation for depth profile measurements of hydrogen isotope atoms contained in graphite.

PubMed

Yorozu, M; Yanagida, T; Nakajyo, T; Okada, Y; Endo, A

2001-04-20

We measured the depth profile of hydrogen atoms in graphite by laser microprobing combined with resonant laser ablation. Deuterium-implanted graphite was employed for the measurements. The sample was ablated by a tunable laser with a wavelength corresponding to the resonant wavelength of 1S-2S of deuterium with two-photon excitation. The ablated deuterium was ionized by a 2 + 1 resonant ionization process. The ions were analyzed by a time-of-flight mass spectrometer. The deuterium ions were detected clearly with the resonant ablation. The detection limit was estimated to be less than 10(16) atoms/cm(3) in our experiments. We determined the depth profile by considering the etching profile and the etching rate. The depth profile agreed well with Monte Carlo simulations to within a precision of 23 mum for the center position and 4-mum precision for distributions for three different implantation depths.

Determination of cocaine, benzoylecgonine and cocaethylene in human hair by solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

de Toledo, Fernanda Crossi Pereira; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2003-12-25

The present work describes a highly precise and sensitive method developed to detect cocaine (COC), benzoylecgonine (BE, its main metabolite) and cocaethylene (CE, transesterification product of the coingestion of COC with ethanol) in human head hair samples. The method was based on an alkylchloroformate derivatization of benzoylecgonine and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification and detection (LOQ and LOD) were: 0.1 ng/mg for COC and CE, and 0.5 ng/mg for BE. Good inter- and intra-assay precision was observed. The dynamic range of the assay was 0.1-50 ng/mg. The method is not time consuming and was shown to be easy to perform.

Aircraft MSS data registration and vegetation classification of wetland change detection

USGS Publications Warehouse

Christensen, E.J.; Jensen, J.R.; Ramsey, Elijah W.; Mackey, H.E.

1988-01-01

Portions of the Savannah River floodplain swamp were evaluated for vegetation change using high resolution (5a??6 m) aircraft multispectral scanner (MSS) data. Image distortion from aircraft movement prevented precise image-to-image registration in some areas. However, when small scenes were used (200-250 ha), a first-order linear transformation provided registration accuracies of less than or equal to one pixel. A larger area was registered using a piecewise linear method. Five major wetland classes were identified and evaluated for change. Phenological differences and the variable distribution of vegetation limited wetland type discrimination. Using unsupervised methods and ground-collected vegetation data, overall classification accuracies ranged from 84 per cent to 87 per cent for each scene. Results suggest that high-resolution aircraft MSS data can be precisely registered, if small areas are used, and that wetland vegetation change can be accurately detected and monitored.

Determination of benzocaine in rainbow trout plasma

USGS Publications Warehouse

Bernardy, Jeffery A.; Coleman, K.S.; Stehly, G.R.; Gingerich, William H.

1996-01-01

A liquid chromatographic method is described for analysis of benzocaine (BZ), a proposed fish anesthetic, in rainbow trout plasma, Mean recoveries of BZ from plasma samples fortified at 44-10 100 ng/mL were 96-100%. The method detection limit is 10 ng/mL, and the limit of quantitation is 37 ng/mL. Acetylation of BZ occurs in whole blood after storage at room temperature (i.e., 21 degrees C) for 10 min. However, no acetylation of BZ was detected in plasma samples held at room temperature for 4 h, Mean method precision for plasma samples with incurred BZ residue is similar to that for fortified samples in the same concentration range (relative standard deviations of 0.9 and 1.2%, respectively).

Ion microscopy with resonant ionization mass spectrometry : time-of-flight depth profiling with improved isotopic precision.

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

Pellin, M. J.; Veryovkin, I. V.; Levine, J.

2010-01-01

There are four generally mutually exclusive requirements that plague many mass spectrometric measurements of trace constituents: (1) the small size (limited by the depth probed) of many interesting materials requires high useful yields to simply detect some trace elements, (2) the low concentrations of interesting elements require efficient discrimination from isobaric interferences, (3) it is often necessary to measure the depth distribution of elements with high surface and low bulk contributions, and (4) many applications require precise isotopic analysis. Resonant ionization mass spectrometry has made dramatic progress in addressing these difficulties over the past five years.

Improvement of a sample preparation procedure for multi-elemental determination in Brazil nuts by ICP-OES.

PubMed

Welna, Maja; Szymczycha-Madeja, Anna

2014-04-01

Various sample preparation procedures, such as common wet digestions and alternatives based on solubilisation in aqua regia or tetramethyl ammonium hydroxide, were compared for the determination of the total Ba, Ca, Cr, Cd, Cu, Fe, Mg, Mn, Ni, P, Pb, Se, Sr and Zn contents in Brazil nuts using inductively coupled plasma optical emission spectrometry (ICP-OES). For measurement of Se, a hydride generation technique was used. The performance of these procedures was measured in terms of precision, accuracy and limits of detection of the elements. It was found that solubilisation in aqua regia gave the best results, i.e. limits of detection from 0.60 to 41.9 ng ml(-1), precision of 1.0-3.9% and accuracy better than 5%. External calibration with simple standard solutions could be applied for the analysis. The proposed procedure is simple, reduces sample handling, and minimises the time and reagent consumption. Thus, this can be a vital alternative to traditional sample treatment approaches based on the total digestion with concentrated reagents. A phenomenon resulting from levels of Ba, Se and Sr in Brazil nuts was also discussed.

Validated enantiospecific LC method for determination of (R)-enantiomer impurity in (S)-efavirenz.

PubMed

Seshachalam, U; Narasimha Rao, D V L; Chandrasekhar, K B

2008-02-01

A high-performance liquid chromatographic method was developed for separation of the enantiomers of efavirenz. The developed method was applied for the determination of (R)-enantiomer in (S)-efavirenz and satisfactory results were achieved. The base line separation with a resolution of more than 4.0 was achieved on Chiralcel OD (250 mm x 4.6 mm, 10 microm) column containing tris-(3,5-dimethylphenylcarbomate) as stationary phase. The mobile phase consists of n-hexane: isopropyl alcohol (80:20 v/v) with 0.1% (v/v) of formic acid as additive. The flow rate was kept at 1.0 ml/min and the UV detection was monitored at 254 nm. The (R)-enantiomer was found linear over the range of 0.1 microg/ml--6 microg/ml. The limit of detection (LOD) was 0.03 microg/ml and the limit of quantification (LOQ) was 0.1 microg/ml (n=3. The precision of (R)-enantiomer at LOQ level was evaluated through six replicate injections and the RSD of the peak response was achieved as 1.34%. The results demonstrated that the developed LC method was simple, precise, robust and applicable for the purity determination of efavirenz.

Performance of a newly designed continuous soot monitoring system (COSMOS).

PubMed

Miyazaki, Yuzo; Kondo, Yutaka; Sahu, Lokesh K; Imaru, Junichi; Fukushima, Nobuhiko; Kano, Minoru

2008-10-01

We designed a continuous soot monitoring system (COSMOS) for fully automated, high-sensitivity, continuous measurement of light absorption by black carbon (BC) aerosols. The instrument monitors changes in transmittance across an automatically advancing quartz fiber filter tape using an LED at a 565 nm wavelength. To achieve measurements with high sensitivity and a lower detectable light absorption coefficient, COSMOS uses a double-convex lens and optical bundle pipes to maintain high light intensity and signal data are obtained at 1000 Hz. In addition, sampling flow rate and optical unit temperature are actively controlled. The inlet line for COSMOS is heated to 400 degrees C to effectively volatilize non-refractory aerosol components that are internally mixed with BC. In its current form, COSMOS provides BC light absorption measurements with a detection limit of 0.45 Mm(-1) (0.045 microg m(-3) for soot) for 10 min. The unit-to-unit variability is estimated to be within +/- 1%, demonstrating its high reproducibility. The absorption coefficients determined by COSMOS agreed with those by a particle soot absorption photometer (PSAP) to within 1% (r2 = 0.97). The precision (+/- 0.60 Mm(-1)) for 10 min integrated data was better than that of PSAP and an aethalometer under our operating conditions. These results showed that COSMOS achieved both an improved detection limit and higher precision for the filter-based light absorption measurements of BC compared to the existing methods.

Radio Detection of Cosmic Rays-Achievements and Future Potential

NASA Astrophysics Data System (ADS)

Huege, Tim

When modern efforts for radio detection of cosmic rays started about a decade ago, hopes were high but the true potential was unknown. Since then, we have achieved a detailed understanding of the radio emission physics and have consequently succeeded in developing sophisticated detection schemes and analysis approaches. In particular, we have demonstrated that the important air-shower parameters arrival direction, particle energy and depth of shower maximum can be reconstructed reliably from radio measurements, with a precision that is comparable with that of other detection techniques. At the same time, limitations inherent to the radio-emission mechanisms have become apparent. In this article, I shortly review the capabilities of radio detection in the very high-frequency band, and discuss the potential for future application in existing and new experiments for cosmic-ray detection.

Automatic stent strut detection in intravascular OCT images using image processing and classification technique

NASA Astrophysics Data System (ADS)

Lu, Hong; Gargesha, Madhusudhana; Wang, Zhao; Chamie, Daniel; Attizani, Guilherme F.; Kanaya, Tomoaki; Ray, Soumya; Costa, Marco A.; Rollins, Andrew M.; Bezerra, Hiram G.; Wilson, David L.

2013-02-01

Intravascular OCT (iOCT) is an imaging modality with ideal resolution and contrast to provide accurate in vivo assessments of tissue healing following stent implantation. Our Cardiovascular Imaging Core Laboratory has served >20 international stent clinical trials with >2000 stents analyzed. Each stent requires 6-16hrs of manual analysis time and we are developing highly automated software to reduce this extreme effort. Using classification technique, physically meaningful image features, forward feature selection to limit overtraining, and leave-one-stent-out cross validation, we detected stent struts. To determine tissue coverage areas, we estimated stent "contours" by fitting detected struts and interpolation points from linearly interpolated tissue depths to a periodic cubic spline. Tissue coverage area was obtained by subtracting lumen area from the stent area. Detection was compared against manual analysis of 40 pullbacks. We obtained recall = 90+/-3% and precision = 89+/-6%. When taking struts deemed not bright enough for manual analysis into consideration, precision improved to 94+/-6%. This approached inter-observer variability (recall = 93%, precision = 96%). Differences in stent and tissue coverage areas are 0.12 +/- 0.41 mm2 and 0.09 +/- 0.42 mm2, respectively. We are developing software which will enable visualization, review, and editing of automated results, so as to provide a comprehensive stent analysis package. This should enable better and cheaper stent clinical trials, so that manufacturers can optimize the myriad of parameters (drug, coverage, bioresorbable versus metal, etc.) for stent design.

Ultrahigh-Sensitivity Piezoresistive Pressure Sensors for Detection of Tiny Pressure.

PubMed

Li, Hongwei; Wu, Kunjie; Xu, Zeyang; Wang, Zhongwu; Meng, Yancheng; Li, Liqiang

2018-06-20

High-sensitivity pressure sensors are crucial for the ultrasensitive touch technology and E-skin, especially at the tiny-pressure range below 100 Pa. However, it is highly challenging to substantially promote sensitivity beyond the current level at several to 200 kPa -1 and to improve the detection limit lower than 0.1 Pa, which is significant for the development of pressure sensors toward ultrasensitive and highly precise detection. Here, we develop an efficient strategy to greatly improve the sensitivity near to 2000 kPa -1 using short-channel coplanar device structure and sharp microstructure, which is systematically proposed for the first time and rationalized by the mathematic calculation and analysis. Significantly, benefiting from the ultrahigh sensitivity, the detection limit is improved to be as small as 0.075 Pa. The sensitivity and detection limit are both superior to the current levels and far surpass the function of human skin. Furthermore, the sensor shows fast response time (50 μs), excellent reproducibility and stability, and low power consumption. Remarkably, the sensor shows excellent detection capacity in the tiny-pressure range, including light-emitting diode switching with a pressure of 7 Pa, ringtone (2-20 Pa) recognition, and ultrasensitive (0.1 Pa) electronic glove. This work represents a performance and strategic progress in the field of pressure sensing.

Method validation for the determination of ochratoxin A in green and soluble coffee by immunoaffinity column cleanup and liquid chromatography.

PubMed

Diaz, G J; Ariza, D; Perilla, N S

2004-06-01

A method was validated for the determination of ochratoxin A (OTA) in soluble and green coffee. Performance parameters evaluated included selectivity, accuracy, intermediate precision, linearity, limit of detection, limit of quantitation, and ruggedness. The method was found to be selective for OTA in both matrices tested. Recovery rates from soluble coffee samples ranged from 73.5 to 91.2%, and from green coffee samples from 68.7 to 84.5%. The intermediate precision (RSDr) was between 9.1 and 9.4% for soluble coffee and between 14.3 and 15.5% for green coffee analysis. The linearity of the standard calibration curve (r(2)) was <0.999 for OTA levels of 1.0-20.0 μg/kg in coffee samples. The limit of detection was determined to be 0.01 ng of OTA on column, while the limit of quantitation was found to be 0.03 ng on column. The limit of quantitation is equivalent to 0.6 μg/kg in soluble coffee samples and 0.3 μg/kg in green coffee samples. The results of the ruggedness trial showed two factors are critical for soluble coffee analysis: the extraction method, and the flow rate of the mobile phase. For green coffee analysis two critical factors detected were the extraction method and the storage temperature of the immunoaffinity column.Five samples of soluble coffee and 42 of green coffee were analysed using the validated method. All soluble coffee samples contained OTA at levels that ranged from 8.4 to 13.9 μg/kg. Six of the 42 green coffee samples analysed (14.3%) contained OTA at levels ranging from 0.9 to 19.4 μg/kg. The validated method can be used to monitor OTA levels in Colombian coffee for export or for local consumption.

[Automated analyzer of enzyme immunoassay].

PubMed

Osawa, S

1995-09-01

Automated analyzers for enzyme immunoassay can be classified by several points of view: the kind of labeled antibodies or enzymes, detection methods, the number of tests per unit time, analytical time and speed per run. In practice, it is important for us consider the several points such as detection limits, the number of tests per unit time, analytical range, and precision. Most of the automated analyzers on the market can randomly access and measure samples. I will describe the recent advance of automated analyzers reviewing their labeling antibodies and enzymes, the detection methods, the number of test per unit time and analytical time and speed per test.

Nanoscale temperature mapping in operating microelectronic devices

DOE PAGES

Mecklenburg, Matthew; Hubbard, William A.; White, E. R.; ...

2015-02-05

We report that modern microelectronic devices have nanoscale features that dissipate power nonuniformly, but fundamental physical limits frustrate efforts to detect the resulting temperature gradients. Contact thermometers disturb the temperature of a small system, while radiation thermometers struggle to beat the diffraction limit. Exploiting the same physics as Fahrenheit’s glass-bulb thermometer, we mapped the thermal expansion of Joule-heated, 80-nanometer-thick aluminum wires by precisely measuring changes in density. With a scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS), we quantified the local density via the energy of aluminum’s bulk plasmon. Rescaling density to temperature yields maps with amore » statistical precision of 3 kelvin/hertz ₋1/2, an accuracy of 10%, and nanometer-scale resolution. Lastly, many common metals and semiconductors have sufficiently sharp plasmon resonances to serve as their own thermometers.« less

Continuous-variable quantum probes for structured environments

NASA Astrophysics Data System (ADS)

Bina, Matteo; Grasselli, Federico; Paris, Matteo G. A.

2018-01-01

We address parameter estimation for structured environments and suggest an effective estimation scheme based on continuous-variables quantum probes. In particular, we investigate the use of a single bosonic mode as a probe for Ohmic reservoirs, and obtain the ultimate quantum limits to the precise estimation of their cutoff frequency. We assume the probe prepared in a Gaussian state and determine the optimal working regime, i.e., the conditions for the maximization of the quantum Fisher information in terms of the initial preparation, the reservoir temperature, and the interaction time. Upon investigating the Fisher information of feasible measurements, we arrive at a remarkable simple result: homodyne detection of canonical variables allows one to achieve the ultimate quantum limit to precision under suitable, mild, conditions. Finally, upon exploiting a perturbative approach, we find the invariant sweet spots of the (tunable) characteristic frequency of the probe, able to drive the probe towards the optimal working regime.

Precision of dehydroascorbic acid quantitation with the use of the subtraction method--validation of HPLC-DAD method for determination of total vitamin C in food.

PubMed

Mazurek, Artur; Jamroz, Jerzy

2015-04-15

In food analysis, a method for determination of vitamin C should enable measuring of total content of ascorbic acid (AA) and dehydroascorbic acid (DHAA) because both chemical forms exhibit biological activity. The aim of the work was to confirm applicability of HPLC-DAD method for analysis of total content of vitamin C (TC) and ascorbic acid in various types of food by determination of validation parameters such as: selectivity, precision, accuracy, linearity and limits of detection and quantitation. The results showed that the method applied for determination of TC and AA was selective, linear and precise. Precision of DHAA determination by the subtraction method was also evaluated. It was revealed that the results of DHAA determination obtained by the subtraction method were not precise which resulted directly from the assumption of this method and the principles of uncertainty propagation. The proposed chromatographic method should be recommended for routine determinations of total vitamin C in various food. Copyright © 2014 Elsevier Ltd. All rights reserved.

Atmospheric boundary layer CO2 remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source.

PubMed

Cadiou, Erwan; Mammez, Dominique; Dherbecourt, Jean-Baptiste; Gorju, Guillaume; Pelon, Jacques; Melkonian, Jean-Michel; Godard, Antoine; Raybaut, Myriam

2017-10-15

We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO 2 in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.

Non-Gaussian precision metrology via driving through quantum phase transitions

NASA Astrophysics Data System (ADS)

Huang, Jiahao; Zhuang, Min; Lee, Chaohong

2018-03-01

We propose a scheme to realize high-precision quantum interferometry with entangled non-Gaussian states by driving the system through quantum phase transitions. The beam splitting, in which an initial nondegenerate ground state evolves into a highly entangled state, is achieved by adiabatically driving the system from a nondegenerate regime to a degenerate one. Inversely, the beam recombination, in which the output state after interrogation becomes gradually disentangled, is accomplished by adiabatically driving the system from the degenerate regime to the nondegenerate one. The phase shift, which is accumulated in the interrogation process, can then be easily inferred via population measurement. We apply our scheme to Bose condensed atoms and trapped ions and find that Heisenberg-limited precision scalings can be approached. Our proposed scheme does not require single-particle resolved detection and is within the reach of current experiment techniques.

A Liquid Chromatography – Tandem Mass Spectrometry Approach for the Identification of Mebendazole Residue in Pork, Chicken, and Horse

PubMed Central

Lee, Ji Sun; Cho, Soo Hee; Lim, Chae Mi; Chang, Moon Ik; Joo, Hyun Jin; Park, Hyun Jin

2017-01-01

A confirmatory and quantitative method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of mebendazole and its hydrolyzed and reduced metabolites in pork, chicken, and horse muscles was developed and validated in this study. Anthelmintic compounds were extracted with ethyl acetate after sample mixture was made alkaline followed by liquid chromatographic separation using a reversed phase C18 column. Gradient elution was performed with a mobile phase consisting of water containing 10 mM ammonium formate and methanol. This confirmatory method was validated according to EU requirements. Evaluated validation parameters included specificity, accuracy, precision (repeatability and within-laboratory reproducibility), analytical limits (decision limit and detection limit), and applicability. Most parameters were proved to be conforming to the EU requirements. The decision limit (CCα) and detection capability (CCβ) for all analytes ranged from 15.84 to 17.96 μgkg-1. The limit of detection (LOD) and the limit of quantification (LOQ) for all analytes were 0.07 μgkg-1 and 0.2 μgkg-1, respectively. The developed method was successfully applied to monitoring samples collected from the markets in major cities and proven great potential to be used as a regulatory tool to determine mebendazole residues in animal based foods. PMID:28085912

Direct liquid chromatography method for the simultaneous quantification of hydroxytyrosol and tyrosol in red wines.

PubMed

Piñeiro, Zulema; Cantos-Villar, Emma; Palma, Miguel; Puertas, Belen

2011-11-09

A validated HPLC method with fluorescence detection for the simultaneous quantification of hydroxytyrosol and tyrosol in red wines is described. Detection conditions for both compounds were optimized (excitation at 279 and 278 and emission at 631 and 598 nm for hydroxytyrosol and tyrosol, respectively). The validation of the analytical method was based on selectivity, linearity, robustness, detection and quantification limits, repeatability, and recovery. The detection and quantification limits in red wines were set at 0.023 and 0.076 mg L(-1) for hydroxytyrosol and at 0.007 and 0.024 mg L(-1) for tyrosol determination, respectively. Precision values, both within-day and between-day (n = 5), remained below 3% for both compounds. In addition, a fractional factorial experimental design was developed to analyze the influence of six different conditions on analysis. The final optimized HPLC-fluorescence method allowed the analysis of 30 nonpretreated Spanish red wines to evaluate their hydroxytyrosol and tyrosol contents.

An automatic device for detection and classification of malaria parasite species in thick blood film.

PubMed

Kaewkamnerd, Saowaluck; Uthaipibull, Chairat; Intarapanich, Apichart; Pannarut, Montri; Chaotheing, Sastra; Tongsima, Sissades

2012-01-01

Current malaria diagnosis relies primarily on microscopic examination of Giemsa-stained thick and thin blood films. This method requires vigorously trained technicians to efficiently detect and classify the malaria parasite species such as Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) for an appropriate drug administration. However, accurate classification of parasite species is difficult to achieve because of inherent technical limitations and human inconsistency. To improve performance of malaria parasite classification, many researchers have proposed automated malaria detection devices using digital image analysis. These image processing tools, however, focus on detection of parasites on thin blood films, which may not detect the existence of parasites due to the parasite scarcity on the thin blood film. The problem is aggravated with low parasitemia condition. Automated detection and classification of parasites on thick blood films, which contain more numbers of parasite per detection area, would address the previous limitation. The prototype of an automatic malaria parasite identification system is equipped with mountable motorized units for controlling the movements of objective lens and microscope stage. This unit was tested for its precision to move objective lens (vertical movement, z-axis) and microscope stage (in x- and y-horizontal movements). The average precision of x-, y- and z-axes movements were 71.481 ± 7.266 μm, 40.009 ± 0.000 μm, and 7.540 ± 0.889 nm, respectively. Classification of parasites on 60 Giemsa-stained thick blood films (40 blood films containing infected red blood cells and 20 control blood films of normal red blood cells) was tested using the image analysis module. By comparing our results with the ones verified by trained malaria microscopists, the prototype detected parasite-positive and parasite-negative blood films at the rate of 95% and 68.5% accuracy, respectively. For classification performance, the thick blood films with Pv parasite was correctly classified with the success rate of 75% while the accuracy of Pf classification was 90%. This work presents an automatic device for both detection and classification of malaria parasite species on thick blood film. The system is based on digital image analysis and featured with motorized stage units, designed to easily be mounted on most conventional light microscopes used in the endemic areas. The constructed motorized module could control the movements of objective lens and microscope stage at high precision for effective acquisition of quality images for analysis. The analysis program could accurately classify parasite species, into Pf or Pv, based on distribution of chromatin size.

Simple, fast and reliable liquid chromatographic and spectrophotometric methods for the determination of theophylline in urine, saliva and plasma samples.

PubMed

Charehsaz, Mohammad; Gürbay, Aylin; Aydin, Ahmet; Sahin, Gönül

2014-01-01

In this study, a high-performance liquid chromatographic method (HPLC) and UV spectrophotometric method were developed, validated and applied for the determination of theophylline in biological fluids. Liquid- liquid extraction is performed for isolation of the drug and elimination of plasma and saliva interferences. Urine samples were applied without any extraction. The chromatographic separation was achieved on a C18 column by using 60:40 methanol:water as mobile phase under isocratic conditions at a flow rate of 0.75 mL/min with UV detection at 280 nm in HPLC method. UV spectrophotometric analysis was performed at 275 nm. the limit of quantification: 1.1 µg/mL for urine, 1.9 µg/mL for saliva, 3.1 µg/mL for plasma; recovery: 94.85% for plasma, 100.45% for saliva, 101.39% for urine; intra-day precision: 0.22-2.33%, inter-day precision: 3.17-13.12%. Spectrophotometric analysis results were as follows: the limit of quantitation: 5.23 µg/mL for plasma, 8.7 µg/mL for urine; recovery: 98.27% for plasma, 95.25% for urine; intra-day precision: 2.37 - 3.00%, inter-day precision: 5.43-7.91%. It can be concluded that this validated HPLC method is easy, precise, accurate, sensitive and selective for determination of theophylline in biological samples. Also spectrophotometric analysis can be used where it can be applicable.

Single Mode, Extreme Precision Doppler Spectrographs

NASA Astrophysics Data System (ADS)

Schwab, Christian; Leon-Saval, Sergio G.; Betters, Christopher H.; Bland-Hawthorn, Joss; Mahadevan, Suvrath

2014-04-01

The `holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Horton 2006, Bland-Hawthorn et al. 2010) and adaptive optics (AO) enable single mode fiber (SMF) fed, high resolution spectrographs, which can realize the next step in precision. SMF feeds have intrinsic advantages over multimode fiber or slit coupled spectrographs: The intensity distribution at the fiber exit is extremely stable, and as a result the line spread function of a well-designed spectrograph is fully decoupled from input coupling conditions, like guiding or seeing variations (Ihle et al. 2010). Modal noise, a limiting factor in current multimode fiber fed instruments (Baudrand & Walker 2001), can be eliminated by proper design, and the diffraction limited input to the spectrograph allows for very compact instrument designs, which provide excellent optomechanical stability. A SMF is the ideal interface for new, very precise wavelength calibrators, like laser frequency combs (Steinmetz et al. 2008, Osterman et al. 2012), or SMF based Fabry-Perot Etalons (Halverson et al. 2013). At near infrared wavelengths, these technologies are ready to be implemented in on-sky instruments, or already in use. We discuss a novel concept for such a spectrograph.

An analysis of I/O efficient order-statistic-based techniques for noise power estimation in the HRMS sky survey's operational system

NASA Technical Reports Server (NTRS)

Zimmerman, G. A.; Olsen, E. T.

1992-01-01

Noise power estimation in the High-Resolution Microwave Survey (HRMS) sky survey element is considered as an example of a constant false alarm rate (CFAR) signal detection problem. Order-statistic-based noise power estimators for CFAR detection are considered in terms of required estimator accuracy and estimator dynamic range. By limiting the dynamic range of the value to be estimated, the performance of an order-statistic estimator can be achieved by simpler techniques requiring only a single pass of the data. Simple threshold-and-count techniques are examined, and it is shown how several parallel threshold-and-count estimation devices can be used to expand the dynamic range to meet HRMS system requirements with minimal hardware complexity. An input/output (I/O) efficient limited-precision order-statistic estimator with wide but limited dynamic range is also examined.

Analysis of eight glycols in serum using LC-ESI-MS-MS.

PubMed

Imbert, Laurent; Saussereau, Elodie; Lacroix, Christian

2014-01-01

A liquid chromatography coupled with electrospray tandem mass spectrometry method was developed for the analysis of ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,2-butanediol, 2,3-butanediol, 1,2-propanediol and 1,3-propanediol, in serum after a Schotten-Baumann derivatization by benzoyl chloride. Usual validation parameters were tested: linearity, repeatability and intermediate precision, limits of detection and quantification, carry over and ion suppression. Limits of detection were between 0.18 and 1.1 mg/L, and limits of quantification were between 0.4 and 2.3 mg/L. Separation of isomers was possible either chromatographically or by selecting specific multiple reaction monitoring transitions. This method could be a useful tool in case of suspected intoxication with antifreeze agents, solvents, dietary supplements or some medical drug compounds. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Broadband noise limit in the photodetection of ultralow jitter optical pulses.

PubMed

Sun, Wenlu; Quinlan, Franklyn; Fortier, Tara M; Deschenes, Jean-Daniel; Fu, Yang; Diddams, Scott A; Campbell, Joe C

2014-11-14

Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption on the photocurrent noise of high-speed photodiodes when detecting ultralow jitter optical pulses. Despite its small contribution to the total photocurrent, this excess noise can determine the phase noise and timing jitter of microwave signals generated by detecting ultrashort optical pulses. A Monte Carlo simulation of the photodetection process is used to quantitatively estimate the excess noise. Simulated phase noise on the 10 GHz harmonic of a photodetected pulse train shows good agreement with previous experimental data, leading to the conclusion that the lowest phase noise photonically generated microwave signals are limited by photocarrier scattering well above the quantum limit of the optical pulse train.

[Radioactive cesium analysis in radiation-tainted beef by gamma-ray spectrometry with germanium semiconductor detector].

PubMed

Minatani, Tomiaki; Nagai, Hiroyuki; Nakamura, Masashi; Otsuka, Kimihito; Sakai, Yoshimichi

2012-01-01

The detection limit and precision of radioactive cesium measurement in beef by gamma-ray spectrometry with a germanium semiconductor detector were evaluated. Measurement for 2,000 seconds using a U-8 container (100 mL) provided a detection limit of radioactive cesium (the sum of 134Cs and 137Cs) of around 20 Bq/kg. The 99% confidence interval of the measurement of provisional maximum residue limit level (491 Bq/kg) samples ranged from 447 to 535 Bq/kg. Beef is heterogeneous, containing muscle and complex fat layers. Depending on the sampled parts, the measurement value is variable. It was found that radioactive cesium content of the muscle layer was clearly different from that of fat, and slight differences were observed among parts of the sample (SD=16.9 Bq/kg), even though the same region (neck block) of beef sample was analyzed.

Detection of Stimulus Displacements Across Saccades is Capacity-Limited and Biased in Favor of the Saccade Target

PubMed Central

Irwin, David E.; Robinson, Maria M.

2015-01-01

Retinal image displacements caused by saccadic eye movements are generally unnoticed. Recent theories have proposed that perceptual stability across saccades depends on a local evaluation process centered on the saccade target object rather than on remapping and evaluating the positions of all objects in a display. In three experiments, we examined whether objects other than the saccade target also influence perceptual stability by measuring displacement detection thresholds across saccades for saccade targets and a variable number of non-saccade objects. We found that the positions of multiple objects are maintained across saccades, but with variable precision, with the saccade target object having priority in the perception of displacement, most likely because it is the focus of attention before the saccade and resides near the fovea after the saccade. The perception of displacement of objects that are not the saccade target is affected by acuity limitations, attentional limitations, and limitations on memory capacity. Unlike previous studies that have found that a postsaccadic blank improves the detection of displacement direction across saccades, we found that postsaccadic blanking hurt the detection of displacement per se by increasing false alarms. Overall, our results are consistent with the hypothesis that visual working memory underlies the perception of stability across saccades. PMID:26640430

Analysis of metalaxyl racemate using high performance liquid chromatography coupled with four kinds of detectors.

PubMed

Chen, Tao; Fan, Jun; Gao, Ruiqi; Wang, Tai; Yu, Ying; Zhang, Weiguang

2016-10-07

Chiral stationary phase-high performance liquid chromatography coupled with various detectors has been one of most commonly used methods for analysis and separation of chiral compounds over the past decades. Various detectors exhibit different characteristics in qualitative and quantitative studies under different chromatographic conditions. Herein, a comparative evaluation of HPLC coupled with ultraviolet, optical rotation, refractive index, and evaporative light scattering detectors has been conducted for qualitative and quantitative analyses of metalaxyl racemate. Effects of separation conditions on the peak area ratio between two enantiomers, including sample concentration, column temperature, mobile phase composition, as well as flow rate, have been investigated in detail. In addition, the limits of detection, the limits of quantitation, quantitative range and precision for these two enantiomers by using four detectors have been also studied. As indicated, the chromatographic separation conditions have been slight effects on ultraviolet and refractive index detections and the peak area ratio between two enantiomers remains almost unchanged, but the evaporative light scattering detection has been significantly affected by the above-mentioned chromatographic conditions and the corresponding peak area ratios varied greatly. Moreover, the limits of detection, the limits of quantitation, and the quantitative ranges of two enantiomers with UV detection were remarkably lower by 1-2 magnitudes than the others. Copyright © 2016 Elsevier B.V. All rights reserved.

Standardization and performance evaluation of "modified" and "ultrasensitive" versions of the Abbott RealTime HIV-1 assay, adapted to quantify minimal residual viremia.

PubMed

Amendola, Alessandra; Bloisi, Maria; Marsella, Patrizia; Sabatini, Rosella; Bibbò, Angela; Angeletti, Claudio; Capobianchi, Maria Rosaria

2011-09-01

Numerous studies investigating clinical significance of HIV-1 minimal residual viremia (MRV) suggest potential utility of assays more sensitive than those routinely used to monitor viral suppression. However currently available methods, based on different technologies, show great variation in detection limit and input plasma volume, and generally suffer from lack of standardization. In order to establish new tools suitable for routine quantification of minimal residual viremia in patients under virological suppression, some modifications were introduced into standard procedure of the Abbott RealTime HIV-1 assay leading to a "modified" and an "ultrasensitive" protocols. The following modifications were introduced: calibration curve extended towards low HIV-1 RNA concentration; 4 fold increased sample volume by concentrating starting material; reduced volume of internal control; adoption of "open-mode" software for quantification. Analytical performances were evaluated using the HIV-1 RNA Working Reagent 1 for NAT assays (NIBSC). Both tests were applied to clinical samples from virologically suppressed patients. The "modified" and the "ultrasensitive" configurations of the assay reached a limit of detection of 18.8 (95% CI: 11.1-51.0 cp/mL) and 4.8 cp/mL (95% CI: 2.6-9.1 cp/mL), respectively, with high precision and accuracy. In clinical samples from virologically suppressed patients, "modified" and "ultrasensitive" protocols allowed to detect and quantify HIV RNA in 12.7% and 46.6%, respectively, of samples resulted "not-detectable", and in 70.0% and 69.5%, respectively, of samples "detected <40 cp/mL" in the standard assay. The "modified" and "ultrasensitive" assays are precise and accurate, and easily adoptable in routine diagnostic laboratories for measuring MRV. Copyright © 2011 Elsevier B.V. All rights reserved.

Multi-dynamic range compressional wave detection using optical-frequency comb

NASA Astrophysics Data System (ADS)

Minamikawa, Takeo; Masuoka, Takashi; Oe, Ryo; Nakajima, Yoshiaki; Yamaoka, Yoshihisa; Minoshima, Kaoru; Yasui, Takeshi

2018-02-01

Compressional wave detection is useful means for health monitoring of building, detection of abnormal vibration of moving objects, defect evaluation, and biomedical imaging such as echography and photoacoustic imaging. The frequency of the compressional wave is varied from quasi-static to a few tens of megahertz depending on applications. Since the dynamic range of general compressional wave detectors is limited, we need to choose a proper compressional wave detector depending on applications. For the compressional wave detection with wide dynamic range, two or more detectors with different detection ranges is required. However, these detectors with different detection ranges generally has different accuracy and precision, disabling the seamless detection over these detection ranges. In this study, we proposed a compressional wave detector employing optical frequency comb (OFC). The compressional wave was sensed with a part of an OFC cavity, being encoded into OFC. The spectrally encoded OFC was converted to radio-frequency by the frequency link nature of OFC. The compressional wave-encoded radio-frequency can therefore be directly measured with a high-speed photodetector. To enhance the dynamic range of the compressional wave detection, we developed a cavityfeedback-based system and a phase-sensitive detection system, both of which the accuracy and precision are coherently linked to these of the OFC. We provided a proof-of-principle demonstration of the detection of compressional wave from quasi-static to ultrasound wave by using the OFC-based compressional wave sensor. Our proposed approach will serve as a unique and powerful tool for detecting compressional wave versatile applications in the future.

Measurement device for high-precision spectral transmittance of solar blind filter

NASA Astrophysics Data System (ADS)

Wang, Yan; Qian, Yunsheng; Lv, Yang; Feng, Cheng; Liu, Jian

2017-02-01

In order to measure spectral transmittance of solar-blind filter ranging from ultraviolet to visible light accurately, a high-precision filter transmittance measuring system based on the ultraviolet photomultiplier is developed. The calibration method is mainly used to measure transmittance in this system, which mainly consists of an ultraviolet photomultiplier as core of the system and a lock-in amplifier combined with an optical modulator as the aided measurement for the system. The ultraviolet photomultiplier can amplify the current signal through the filter and have the characteristics of low dark current and high luminance gain. The optical modulator and the lock-in amplifier can obtain the signal from the photomultiplier and inhibit dark noise and spurious signal effectively. Through these two parts, the low light passing through the filters can be detected and we can calculate the transmittance by the optical power detected. Based on the proposed system, the limit detection of the transmittance can reach 10-12, while the result of the conventional approach is merely 10-6. Therefore, the system can make an effective assessment of solar blind ultraviolet filters.

Rapid determination of five antibiotic residues in swine wastewater by online solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Tagiri-Endo, Misako; Suzuki, Shigeru; Nakamura, Tomoyuki; Hatakeyama, Takashi; Kawamukai, Kazuo

2009-02-01

A simple and quick online solid-phase extraction (SPE) coupled to liquid chromatography (LC)/tandem mass spectrometry (MS/MS) for the determination of the five antibiotics (florfenicol, FF; lincomycin, LCM; oxytetracyclin, OTC; tylosin, TS; valnemulin, VLM) in swine wastewater has been developed. After filtration, aliquots (100 microl) of wastewater samples were directly injected to a column-switching LC system. Some matrix interference was removed by washing up SPE column with 0.2% formic acid solution and acetonitrile. Antibiotics eluted from SPE column were separated on analytical column by converting switching valve and were detected by MS/MS. Calibration curves using the method of standard addition had very good correlation coefficients (r > 0.99) in the range of 0.1 to 2 ng/ml. The intra-day precision of the method was less than 12% and the inter-day precision was between 6 to 17%. The detection limits were 0.01-0.1 ng/ml. When this method was applied to wastewater samples in swine facilities, four compounds (LCM, OTC, TS, and VLM) were detected.

An improved method for precise automatic co-registration of moderate and high-resolution spacecraft imagery

NASA Technical Reports Server (NTRS)

Bryant, Nevin A.; Logan, Thomas L.; Zobrist, Albert L.

2006-01-01

Improvements to the automated co-registration and change detection software package, AFIDS (Automatic Fusion of Image Data System) has recently completed development for and validation by NGA/GIAT. The improvements involve the integration of the AFIDS ultra-fine gridding technique for horizontal displacement compensation with the recently evolved use of Rational Polynomial Functions/ Coefficients (RPFs/RPCs) for image raster pixel position to Latitude/Longitude indexing. Mapping and orthorectification (correction for elevation effects) of satellite imagery defies exact projective solutions because the data are not obtained from a single point (like a camera), but as a continuous process from the orbital path. Standard image processing techniques can apply approximate solutions, but advances in the state-of-the-art had to be made for precision change-detection and time-series applications where relief offsets become a controlling factor. The earlier AFIDS procedure required the availability of a camera model and knowledge of the satellite platform ephemeredes. The recent design advances connect the spacecraft sensor Rational Polynomial Function, a deductively developed model, with the AFIDS ultrafine grid, an inductively developed representation of the relationship raster pixel position to latitude /longitude. As a result, RPCs can be updated by AFIDS, a situation often necessary due to the accuracy limits of spacecraft navigation systems. An example of precision change detection will be presented from Quickbird.

Enantioselective determination of the organochlorine pesticide bromocyclen in spiked fish tissue using solid-phase microextraction coupled to gas chromatography with ECD and ICP-MS detection.

PubMed

Fidalgo-Used, Natalia; Montes-Bayón, Maria; Blanco-González, Elisa; Sanz-Medel, Alfredo

2008-05-15

A method for enantioselective determination of bromocyclen enantiomers in fish tissue has been developed. The enantiomers were resolved by capillary gas chromatography (GC) using a commercial chiral column (CP-Chirasil-Dex CB) and a temperature program from 50 degrees C (held for 1 min), raised to 140 degrees C at 40 degrees C min(-1) and then raised at 0.2 degrees C min(-1) to 155 degrees C. This enantioselective gas chromatographic separation was combined with a clean-up/enrichment procedure based on solid-phase microextraction (SPME). Under SPME optimized conditions, precision, linearity range and detection limits of the developed SPME-enantioselective GC procedure were evaluated and compared using two different detection systems: a classical electron-capture detection (ECD) and an element specific detection using inductively coupled plasma mass spectrometry (ICP-MS). The SPME-GC-ECD method exhibited an excellent sensitivity, with detection limits of 0.2 ng L(-1) for each enantiomer of bromocyclen. Although ICP-MS offered poorer detection limits (7 ng L(-1) as Br, equivalent to 36 ng L(-1) of each enantiomer) than conventional ECD detector, it proved to be clearly superior in terms of selectivity. The relative potential and performance of the two compared methods for real-life analysis has been illustrated by the determination of enantiomers of bromocyclen in spiked tissue extracts of trout.

Technological advances in diagnostic testing for von Willebrand disease: new approaches and challenges.

PubMed

Hayward, C P M; Moffat, K A; Graf, L

2014-06-01

Diagnostic tests for von Willebrand disease (VWD) are important for the assessment of VWD, which is a commonly encountered bleeding disorder worldwide. Technical innovations have been applied to improve the precision and lower limit of detection of von Willebrand factor (VWF) assays, including the ristocetin cofactor activity assay (VWF:RCo) that uses the antibiotic ristocetin to induce plasma VWF binding to glycoprotein (GP) IbIXV on target platelets. VWF-collagen-binding assays, depending on the type of collagen used, can improve the detection of forms of VWD with high molecular weight VWF multimer loss, although the best method is debatable. A number of innovations have been applied to VWF:RCo (which is commonly performed on an aggregometer), including replacing the target platelets with immobilized GPIbα, and quantification by an enzyme-linked immunosorbent assay (ELISA), immunoturbidimetric, or chemiluminescent end-point. Some common polymorphisms in the VWF gene that do not cause bleeding are associated with falsely low VWF activity by ristocetin-dependent methods. To overcome the need for ristocetin, some new VWF activity assays use gain-of-function GPIbα mutants that bind VWF without the need for ristocetin, with an improved precision and lower limit of detection than measuring VWF:RCo by aggregometry. ELISA of VWF binding to mutated GPIbα shows promise as a method to identify gain-of-function defects from type 2B VWD. The performance characteristics of many new VWF activity assays suggest that the detection of VWD, and monitoring of VWD therapy, by clinical laboratories could be improved through adopting newer generation VWF assays. © 2014 John Wiley & Sons Ltd.

Simple determination of L-hydroxyproline in idiopathic pulmonary fibrosis lung tissues of rats using non-extractive high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization with novel synthetic 9-acetylimidazol-carbazole.

PubMed

Ren, Yan; Zhao, Juanjuan; Shi, Yanan; Chen, Caiyun; Chen, Xiangming; Lv, Changjun

2017-08-05

L-Hydroxyproline (L-Hyp) is an important biomarker for idiopathic pulmonary fibrosis (IPF). The quantitative methods based on high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization typically requires complicated derivatization conditions and obtains unstable derivatives. Here, a novel derivatization reagent, 9-acetylimidazol-carbazole, was synthesized for the first time to efficiently and rapidly label the amino groups of L-Hyp. The high-performance liquid chromatography method with pre-column derivatization was performed on an Agilent ZORBAX SB-C 18 column (4.6×250mm, 5μm). The product was measured using fluorescence detection at excitation and emission wavelengths of 232 and 370nm, respectively. The method was validated in specificity, linearity, limit of detection (66.7 fmol), limit of quantification (333.3fmol), intra-day precision (0.75%), inter-day precision (3.82%), stability (3.15%), and recovery (90.7-109.4%). The validated method was successfully applied to the determination of L-Hyp in the lung tissues of healthy and IPF rats. The results showed that the concentration of L-Hyp (3.64mg/g) in the IPF model was significantly higher than the concentration (2.33mg/g) in the healthy control group with P<0.01. This is a new method for the determination of L-Hyp and can be used for other amino acid-related studies in the future. Copyright © 2017. Published by Elsevier B.V.

Detection And Mapping (DAM) package. Volume 4B: Software System Manual, part 2

NASA Technical Reports Server (NTRS)

Schlosser, E. H.

1980-01-01

Computer programs, graphic devices, and an integrated set of manual procedures designed for efficient production of precisely registered and formatted maps from digital data are presented. The software can be used on any Univac 1100 series computer. The software includes pre-defined spectral limits for use in classifying and mapping surface water for LANDSAT-1, LANDSAT-2, and LANDSAT-3.

Border effect-based precise measurement of any frequency signal

NASA Astrophysics Data System (ADS)

Bai, Li-Na; Ye, Bo; Xuan, Mei-Na; Jin, Yu-Zhen; Zhou, Wei

2015-12-01

Limited detection resolution leads to fuzzy areas during the measurement, and the discrimination of the border of a fuzzy area helps to use the resolution stability. In this way, measurement precision is greatly improved, hence this phenomenon is named the border effect. The resolution fuzzy area and its application should be studied to realize high-resolution measurement. During the measurement of any frequency signal, the fuzzy areas of phase-coincidence detection are always discrete and irregular. In this paper the difficulty in capturing the border information of discrete fuzzy areas is overcome and extra-high resolution measurement is implemented. Measurement precision of any frequency-signal can easily reach better than 1 × 10-11/s in a wide range of frequencies, showing the great importance of the border effect. An in-depth study of this issue has great significance for frequency standard comparison, signal processing, telecommunication, and fundamental subjects. Project supported by the National Natural Science Foundation of China (Grant Nos. 10978017 and 61201288), the Natural Science Foundation of Research Plan Projects of Shaanxi Province, China (Grant No. 2014JM2-6128), and the Sino-Poland Science and Technology Cooperation Projects (Grant No. 36-33).

Characterization Of Nuclear Materials Using Time-Of-Flight ICP-MS

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

Buerger, Stefan; Riciputi, Lee R; Bostick, Debra A

2006-01-01

The investigation of illicit trafficking of nuclear materials, nuclear safeguards analysis, and non-proliferation control requires sensitive and isotope-selective detection methods to gain crucial nuclear forensic information like isotope 'fingerprints' and multi-element signatures. The advantage of time-of-flight (TOF) mass spectrometry - quasi-simultaneous multi-mass analysis - combined with an inductively coupled plasma (ICP) ion source provides an analytical instrument with multi-element and multi-isotope capability and good detection limits. A TOF-ICP-MS system thus appears to be an advantageous choice for the investigation and characterization of nuclear materials. We present here results using a GBC OptiMass 8000 time-of-flight ICP-MS for the isotope screening ofmore » solid samples by laser ablation and the multi-element determination of impurities in uranium ore concentrates using matrix matched standards. A laser ablation system (New Wave Research, UP 213) coupled to the TOF-ICP-MS instrument has been used to optimize the system for analysis of non-radioactive metal samples of natural isotopic composition for a variety of elements including Cu, Sr, Zr, Mo, Cd, In, Ba, Ta, W, Re, Pt, and Pb in pure metals, alloys, and glasses to explore precision, accuracy, and detection limits. Similar methods were then applied to measure uranium. When the laser system is optimized, no mass bias correction is required. Precision and accuracy for the determination of the isotopic composition is typically 1 - 3% for elemental concentrations of as little as 50 ppm in the matrix, with no requirement for sample preparation. The laser ablation precision and accuracy are within ~10x of the instrumental limits for liquid analysis (0.1%). We have investigated the capabilities of the TOF-ICP-MS for the analysis of impurities in uranium matrices. Matrix matching has been used to develop calibration curves for a range of impurities (alkaline, earth-alkaline, transition metals, and rare earth elements). These calibration curves have been used to measure impurities in a number of uranium samples. The results from the TOF-ICP-MS will be compared with other mass spectrometric methods.« less

Analytical Method Development and Validation for the Simultaneous Estimation of Abacavir and Lamivudine by Reversed-phase High-performance Liquid Chromatography in Bulk and Tablet Dosage Forms.

PubMed

Raees Ahmad, Sufiyan Ahmad; Patil, Lalit; Mohammed Usman, Mohammed Rageeb; Imran, Mohammad; Akhtar, Rashid

2018-01-01

A simple rapid, accurate, precise, and reproducible validated reverse phase high performance liquid chromatography (HPLC) method was developed for the determination of Abacavir (ABAC) and Lamivudine (LAMI) in bulk and tablet dosage forms. The quantification was carried out using Symmetry Premsil C18 (250 mm × 4.6 mm, 5 μm) column run in isocratic way using mobile phase comprising methanol: water (0.05% orthophosphoric acid with pH 3) 83:17 v/v and a detection wavelength of 245 nm and injection volume of 20 μl, with a flow rate of 1 ml/min. In the developed method, the retention times of ABAC and LAMI were found to be 3.5 min and 7.4 min, respectively. The method was validated in terms of linearity, precision, accuracy, limits of detection, limits of quantitation, and robustness in accordance with the International Conference on Harmonization guidelines. The assay of the proposed method was found to be 99% - 101%. The recovery studies were also carried out and mean % recovery was found to be 99% - 101%. The % relative standard deviation from reproducibility was found to be <2%. The proposed method was statistically evaluated and can be applied for routine quality control analysis of ABAC and LAMI in bulk and in tablet dosage form. Attempts were made to develop RP-HPLC method for simultaneous estimation of Abacavir and Lamivudine for the RP-HPLC method. The developed method was validated according to the ICH guidelines. The linearity, precision, range, robustness were within the limits as specified by the ICH guidelines. Hence the method was found to be simple, accurate, precise, economic and reproducible. So the proposed methods can be used for the routine quality control analysis of Abacavir and Lamivudine in bulk drug as well as in formulations. Abbreviations Used: HPLC: High-performance liquid chromatography, UV: Ultraviolet, ICH: International Conference on Harmonization, ABAC: Abacavir, LAMI: Lamivudine, HIV: Human immunodeficiency virus, AIDS: Acquired immunodeficiency syndrome, NRTI: Nucleoside reverse transcriptase inhibitors, ARV: Antiretroviral, RSD: Relative standard deviation, RT: Retention time, SD: Standard deviation.

Plasmodium vivax molecular diagnostics in community surveys: pitfalls and solutions.

PubMed

Gruenberg, Maria; Moniz, Clara Antunes; Hofmann, Natalie Ellen; Wampfler, Rahel; Koepfli, Cristian; Mueller, Ivo; Monteiro, Wuelton Marcelo; Lacerda, Marcus; de Melo, Gisely Cardoso; Kuehn, Andrea; Siqueira, Andre M; Felger, Ingrid

2018-01-30

A distinctive feature of Plasmodium vivax infections is the overall low parasite density in peripheral blood. Thus, identifying asymptomatic infected individuals in endemic communities requires diagnostic tests with high sensitivity. The detection limits of molecular diagnostic tests are primarily defined by the volume of blood analysed and by the copy number of the amplified molecular marker serving as the template for amplification. By using mitochondrial DNA as the multi-copy template, the detection limit can be improved more than tenfold, compared to standard 18S rRNA targets, thereby allowing detection of lower parasite densities. In a very low transmission area in Brazil, application of a mitochondrial DNA-based assay increased prevalence from 4.9 to 6.5%. The usefulness of molecular tests in malaria epidemiological studies is widely recognized, especially when precise prevalence rates are desired. Of concern, however, is the challenge of demonstrating test accuracy and quality control for samples with very low parasite densities. In this case, chance effects in template distribution around the detection limit constrain reproducibility. Rigorous assessment of false positive and false negative test results is, therefore, required to prevent over- or under-estimation of parasite prevalence in epidemiological studies or when monitoring interventions.

Simultaneous Proteomic Discovery and Targeted Monitoring using Liquid Chromatography, Ion Mobility Spectrometry, and Mass Spectrometry*

PubMed Central

Burnum-Johnson, Kristin E.; Nie, Song; Casey, Cameron P.; Monroe, Matthew E.; Orton, Daniel J.; Ibrahim, Yehia M.; Gritsenko, Marina A.; Clauss, Therese R. W.; Shukla, Anil K.; Moore, Ronald J.; Purvine, Samuel O.; Shi, Tujin; Qian, Weijun; Liu, Tao; Baker, Erin S.; Smith, Richard D.

2016-01-01

Current proteomic approaches include both broad discovery measurements and quantitative targeted analyses. In many cases, discovery measurements are initially used to identify potentially important proteins (e.g. candidate biomarkers) and then targeted studies are employed to quantify a limited number of selected proteins. Both approaches, however, suffer from limitations. Discovery measurements aim to sample the whole proteome but have lower sensitivity, accuracy, and quantitation precision than targeted approaches, whereas targeted measurements are significantly more sensitive but only sample a limited portion of the proteome. Herein, we describe a new approach that performs both discovery and targeted monitoring (DTM) in a single analysis by combining liquid chromatography, ion mobility spectrometry and mass spectrometry (LC-IMS-MS). In DTM, heavy labeled target peptides are spiked into tryptic digests and both the labeled and unlabeled peptides are detected using LC-IMS-MS instrumentation. Compared with the broad LC-MS discovery measurements, DTM yields greater peptide/protein coverage and detects lower abundance species. DTM also achieved detection limits similar to selected reaction monitoring (SRM) indicating its potential for combined high quality discovery and targeted analyses, which is a significant step toward the convergence of discovery and targeted approaches. PMID:27670688

Molecular Detection of 10 of the Most Unwanted Alien Forest Pathogens in Canada Using Real-Time PCR

PubMed Central

Lamarche, Josyanne; Potvin, Amélie; Pelletier, Gervais; Stewart, Don; Feau, Nicolas; Alayon, Dario I. O.; Dale, Angela L.; Coelho, Aaron; Uzunovic, Adnan; Bilodeau, Guillaume J.; Brière, Stephan C.; Hamelin, Richard C.; Tanguay, Philippe

2015-01-01

Invasive alien tree pathogens can cause significant economic losses as well as large-scale damage to natural ecosystems. Early detection to prevent their establishment and spread is an important approach used by several national plant protection organizations (NPPOs). Molecular detection tools targeting 10 of the most unwanted alien forest pathogens in Canada were developed as part of the TAIGA project (http://taigaforesthealth.com/). Forest pathogens were selected following an independent prioritization. Specific TaqMan real-time PCR detection assays were designed to function under homogeneous conditions so that they may be used in 96- or 384-well plate format arrays for high-throughput testing of large numbers of samples against multiple targets. Assays were validated for 1) specificity, 2) sensitivity, 3) precision, and 4) robustness on environmental samples. All assays were highly specific when evaluated against a panel of pure cultures of target and phylogenetically closely-related species. Sensitivity, evaluated by assessing the limit of detection (with a threshold of 95% of positive samples), was found to be between one and ten target gene region copies. Precision or repeatability of each assay revealed a mean coefficient of variation of 3.4%. All assays successfully allowed detection of target pathogen on positive environmental samples, without any non-specific amplification. These molecular detection tools will allow for rapid and reliable detection of 10 of the most unwanted alien forest pathogens in Canada. PMID:26274489

Performance evaluation of the automated nucleated red blood cell count of five commercial hematological analyzers.

PubMed

Da Rin, G; Vidali, M; Balboni, F; Benegiamo, A; Borin, M; Ciardelli, M L; Dima, F; Di Fabio, A; Fanelli, A; Fiorini, F; Francione, S; Germagnoli, L; Gioia, M; Lari, T; Lorubbio, M; Marini, A; Papa, A; Seghezzi, M; Solarino, L; Pipitone, S; Tilocca, E; Buoro, S

2017-12-01

Recent automated hematology analyzers (HAs) can identify and report nucleated red blood cells (NRBC) count as a separate population out of white blood cells (WBC). The aim of this study was to investigate the analytical performances of NRBC enumeration on five top of the range HAs. We evaluated the within-run and between-day precision, limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) of XE-2100 and XN-module (Sysmex), ADVIA 2120i (Siemens), BC-6800 (Mindray), and UniCel DxH 800 (Beckman Coulter). Automated NRBC counts were also compared with optical microscopy (OM). The limits of detection for NRBC of the BC-6800, XN-module, XE-2100, UniCel DxH 800, and ADVIA 2120i are 0.035×10 9 /L, 0.019×10 9 /L, 0.067×10 9 /L, 0.038×10 9 /L, and 0.167×10 9 /L, respectively. Our data indicated excellent performance in terms of precision. The agreement with OM was excellent for BC-6800, XN-module, and XE-2100 (Bias 0.023, 0.019, and 0.033×10 9 /L, respectively). ADVIA 2120i displayed a significant constant error and UniCel DxH 800 both proportional and small constant error. Regards to NRBC counting, the performances shown by BC-6800, XN-module, and XE-2100 are excellent also a low count, ADVIA 2120i and UniCel DxH 800 need to be improved. © 2017 John Wiley & Sons Ltd.

Development and validation of a UPLC method for the determination of duloxetine hydrochloride residues on pharmaceutical manufacturing equipment surfaces

PubMed Central

Kumar, Navneet; Sangeetha, D.; Balakrishna, P.

2011-01-01

Background: In pharmaceutical industries, it is very important to remove drug residues from the equipment and areas used. The cleaning procedure must be validated, so special attention must be devoted to the methods used for analysis of trace amounts of drugs. A rapid, sensitive, and specific reverse phase ultra-performance liquid chromatographic (UPLC) method was developed for the quantitative determination of duloxetine in cleaning validation swab samples. Material and Methods: The method was validated using an Acquity UPLC™ HSS T3 (100 × 2.1 mm2) 1.8 μm column with a isocratic mobile phase containing a mixture of 0.01 M potassium dihydrogen orthophosphate, pH adjusted to 3.0 with orthophosphoric acid and acetonitrile (60:40 v/v). The flow rate of the mobile phase was 0.4 ml/min with a column temperature of 40°C and detection wavelength at 230 nm. Cotton swabs, moisten with extraction solution (90% methanol and 10% water), were used to remove any residue of drug from stainless steel, glass and silica surfaces, and give recoveries >80% at four concentration levels. Results: The precision of the results, reported as the relative standard deviation, were below 1.5%. The calibration curve was linear over a concentration range from 0.02 to 5.0 μg/ml with a correlation coefficient of 0.999. The detection limit and quantitation limit were 0.006 and 0.02 μg/ml, respectively. The method was validated over a concentration range of 0.05–5.0 μg/ml. Conclusion: The developed method was validated with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness. PMID:23781449

[Determination of doping in human urine by gas chromatography-high resolution mass spectrometry].

PubMed

Xing, Yan-Yi; Liu, Xin; Zhang, Yu-Mei; Wang, Xiao-Bing; Xu, You-Xuan

2012-12-01

A method was evaluated for determination of twenty-one doping (including nandrolone, boldenone and methandienone) in human urine by gas chromatography-high resolution mass spectrometry. Samples were prepared by liquid-liquid extraction, concentrated, TMS derivatization and limit of detection at ng x mL(-1) by MID/GC/HRMS. According to the code of the World Anti-Doping Agency (WADA), precision and recoveries of the procedure were evaluated by replicate analysis (n = 6), the recoveries in the range of 66%-103%, with the RSD below 10.0%. The precision within the day of the method with three different concentrations was also determined RSD were less than 9.5%, 10.0% and 9.7%.

Determination of Vitamin E in Cereal Products and Biscuits by GC-FID.

PubMed

Pasias, Ioannis N; Kiriakou, Ioannis K; Papakonstantinou, Lila; Proestos, Charalampos

2018-01-01

A rapid, precise and accurate method for the determination of vitamin E (α-tocopherol) in cereal products and biscuits has been developed. The uncertainty was calculated for the first time, and the methods were performed for different cereal products and biscuits, characterized as "superfoods". The limits of detection and quantification were calculated. The accuracy and precision were estimated using the certified reference material FAPAS T10112QC, and the determined values were in good accordance with the certified values. The health claims according to the daily reference values for vitamin E were calculated, and the results proved that the majority of the samples examined showed a percentage daily value higher than 15%.

Determination of Vitamin E in Cereal Products and Biscuits by GC-FID

PubMed Central

Kiriakou, Ioannis K.; Papakonstantinou, Lila

2018-01-01

A rapid, precise and accurate method for the determination of vitamin E (α-tocopherol) in cereal products and biscuits has been developed. The uncertainty was calculated for the first time, and the methods were performed for different cereal products and biscuits, characterized as “superfoods”. The limits of detection and quantification were calculated. The accuracy and precision were estimated using the certified reference material FAPAS T10112QC, and the determined values were in good accordance with the certified values. The health claims according to the daily reference values for vitamin E were calculated, and the results proved that the majority of the samples examined showed a percentage daily value higher than 15%. PMID:29301245

Validation of high throughput screening of human sera for detection of anti-PA IgG by Enzyme-Linked Immunosorbent Assay (ELISA) as an emergency response to an anthrax incident

PubMed Central

Semenova, Vera A.; Steward-Clark, Evelene; Maniatis, Panagiotis; Epperson, Monica; Sabnis, Amit; Schiffer, Jarad

2017-01-01

To improve surge testing capability for a response to a release of Bacillus anthracis, the CDC anti-Protective Antigen (PA) IgG Enzyme-Linked Immunosorbent Assay (ELISA) was re-designed into a high throughput screening format. The following assay performance parameters were evaluated: goodness of fit (measured as the mean reference standard r2), accuracy (measured as percent error), precision (measured as coefficient of variance (CV)), lower limit of detection (LLOD), lower limit of quantification (LLOQ), dilutional linearity, diagnostic sensitivity (DSN) and diagnostic specificity (DSP). The paired sets of data for each sample were evaluated by Concordance Correlation Coefficient (CCC) analysis. The goodness of fit was 0.999; percent error between the expected and observed concentration for each sample ranged from −4.6% to 14.4%. The coefficient of variance ranged from 9.0% to 21.2%. The assay LLOQ was 2.6 μg/mL. The regression analysis results for dilutional linearity data were r2 = 0.952, slope = 1.02 and intercept = −0.03. CCC between assays was 0.974 for the median concentration of serum samples. The accuracy and precision components of CCC were 0.997 and 0.977, respectively. This high throughput screening assay is precise, accurate, sensitive and specific. Anti-PA IgG concentrations determined using two different assays proved high levels of agreement. The method will improve surge testing capability 18-fold from 4 to 72 sera per assay plate. PMID:27814939

Validation of high throughput screening of human sera for detection of anti-PA IgG by Enzyme-Linked Immunosorbent Assay (ELISA) as an emergency response to an anthrax incident.

PubMed

Semenova, Vera A; Steward-Clark, Evelene; Maniatis, Panagiotis; Epperson, Monica; Sabnis, Amit; Schiffer, Jarad

2017-01-01

To improve surge testing capability for a response to a release of Bacillus anthracis, the CDC anti-Protective Antigen (PA) IgG Enzyme-Linked Immunosorbent Assay (ELISA) was re-designed into a high throughput screening format. The following assay performance parameters were evaluated: goodness of fit (measured as the mean reference standard r 2 ), accuracy (measured as percent error), precision (measured as coefficient of variance (CV)), lower limit of detection (LLOD), lower limit of quantification (LLOQ), dilutional linearity, diagnostic sensitivity (DSN) and diagnostic specificity (DSP). The paired sets of data for each sample were evaluated by Concordance Correlation Coefficient (CCC) analysis. The goodness of fit was 0.999; percent error between the expected and observed concentration for each sample ranged from -4.6% to 14.4%. The coefficient of variance ranged from 9.0% to 21.2%. The assay LLOQ was 2.6 μg/mL. The regression analysis results for dilutional linearity data were r 2  = 0.952, slope = 1.02 and intercept = -0.03. CCC between assays was 0.974 for the median concentration of serum samples. The accuracy and precision components of CCC were 0.997 and 0.977, respectively. This high throughput screening assay is precise, accurate, sensitive and specific. Anti-PA IgG concentrations determined using two different assays proved high levels of agreement. The method will improve surge testing capability 18-fold from 4 to 72 sera per assay plate. Published by Elsevier Ltd.

Evaluation of a method for determining concentrations of isoeugenol, an AQUI-S residue, in fillet tissue from freshwater fish species.

USGS Publications Warehouse

Meinertz, J.R.; Schreier, Theresa M.; Bernardy, J.A.

2008-01-01

AQUI-S is a fish anesthetic/sedative that is approved for use in a number of countries throughout the world and has the potential for use in the United States. The active ingredient in AQUI-S is isoeugenol. A method for determining isoeugenol concentrations in edible fillet tissue is needed for regulatory purposes, including surveillance and potential use in studies fulfilling human food safety data requirements if U.S. Food and Drug Administration approval is pursued. A method was developed and evaluated for determining isoeugenol concentrations in fillet tissue using relatively common procedures and equipment. The method produced accurate and precise results with fillet tissue from 10 freshwater fish species. The percentage of isoeugenol recovered from samples fortified with isoeugenol at nominal concentrations of 1, 50, and 100 microg/g for all species was always >80 and <97%. Within-day precision for samples fortified at those same concentrations was < or =10%, and day-to-day precision was < or =4.0%. Method precision with fillet tissue containing biologically incurred isoeugenol was < or =8.1%. There were no or minimal chromatographic interferences in control fillet tissue extracts from 9 of the 10 species. The method detection limits for all but one species ranged from 0.004 to 0.014 microg/g, and the quantitation limits ranged from 0.012 to 0.048 microg/g.

[Determination of four bisphenolic compounds in drinking water by liquid chromatography-tandem mass spectrometry].

PubMed

Hu, Xiaojian; Zhang, Haijing; Wang, Xiaohong; Ding, Changming; Lin, Shaobin

2015-05-01

To simultaneously determine the four bisphenolic compounds (bisphenol F, bisphenol A, tetrachlorobisphenol A and tetrabromobisphenol A) in drinking water by liquid chromatography tandem mass spectrometry. 200 ml water sample was extracted by solid-phase extraction, eluted with methanol and analyzed by liquid chromatography tandem mass spectrometry under the MRM mode. The separation was carried out on a T3 column (2.1 mm x 150 mm, 3 μm). The limits of detection for the four bisphenolic compounds were in the range of 0.20 - 5.5 ng/L. The mean recoveries at the two spiked levels were 87.1% - 109.0% with the intra-day precision between 6.3% - 12.4% and inter-day precision between 4.5% - 15.4%. The method was applied for determination of 15 water samples. The method was sensitive, precise and accurate.

Validation of the LacTek test applied to spiked extracts of tissue samples: determination of performance characteristics.

PubMed

Mitchell, J M; Yee, A J; McNab, W B; Griffiths, M W; McEwen, S A

1999-01-01

LacTek tests are competitive enzyme-linked immunosorbent assays intended for rapid detection of antimicrobial residues in bovine milk. In this study, the LacTek test protocol was modified for use with extracts of bovine tissue to detect beta-lactam, tetracycline, and sulfamethazine residues. Test performance characteristics--precision, accuracy, ruggedness, practicability, and analytical specificity and sensitivity--were investigated. Results suggest that LacTek tests can be easily adapted to detect antimicrobial residues in extracts of lean ground beef. However, positive samples may not contain residues at violative concentrations (i.e., Canadian maximum residue limits), and therefore, additional analysis would be required for final confirmation and quantitation (e.g., chromatography).

Application of 3D Laser Scanning Technology in Inspection and Dynamic Reserves Detection of Open-Pit Mine

NASA Astrophysics Data System (ADS)

Hu, Zhumin; Wei, Shiyu; Jiang, Jun

2017-10-01

The traditional open-pit mine mining rights verification and dynamic reserve detection means rely on the total station and RTK to collect the results of the turning point coordinates of mining surface contours. It resulted in obtaining the results of low precision and large error in the means that is limited by the traditional measurement equipment accuracy and measurement methods. The three-dimensional scanning technology can obtain the three-dimensional coordinate data of the surface of the measured object in a large area at high resolution. This paper expounds the commonly used application of 3D scanning technology in the inspection and dynamic reserve detection of open mine mining rights.

Digital PCR analysis of circulating nucleic acids.

PubMed

Hudecova, Irena

2015-10-01

Detection of plasma circulating nucleic acids (CNAs) requires the use of extremely sensitive and precise methods. The commonly used quantitative real-time polymerase chain reaction (PCR) poses certain technical limitations in relation to the precise measurement of CNAs whereas the costs of massively parallel sequencing are still relatively high. Digital PCR (dPCR) now represents an affordable and powerful single molecule counting strategy to detect minute amounts of genetic material with performance surpassing many quantitative methods. Microfluidic (chip) and emulsion (droplet)-based technologies have already been integrated into platforms offering hundreds to millions of nanoliter- or even picoliter-scale reaction partitions. The compelling observations reported in the field of cancer research, prenatal testing, transplantation medicine and virology support translation of this technology into routine use. Extremely sensitive plasma detection of rare mutations originating from tumor or placental cells among a large background of homologous sequences facilitates unraveling of the early stages of cancer or the detection of fetal mutations. Digital measurement of quantitative changes in plasma CNAs associated with cancer or graft rejection provides valuable information on the monitoring of disease burden or the recipient's immune response and subsequent therapy treatment. Furthermore, careful quantitative assessment of the viral load offers great value for effective monitoring of antiviral therapy for immunosuppressed or transplant patients. The present review describes the inherent features of dPCR that make it exceptionally robust in precise and sensitive quantification of CNAs. Moreover, I provide an insight into the types of potential clinical applications that have been developed by researchers to date. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Crowded field photometry with deconvolved images.

NASA Astrophysics Data System (ADS)

Linde, P.; Spännare, S.

A local implementation of the Lucy-Richardson algorithm has been used to deconvolve a set of crowded stellar field images. The effects of deconvolution on detection limits as well as on photometric and astrometric properties have been investigated as a function of the number of deconvolution iterations. Results show that deconvolution improves detection of faint stars, although artifacts are also found. Deconvolution provides more stars measurable without significant degradation of positional accuracy. The photometric precision is affected by deconvolution in several ways. Errors due to unresolved images are notably reduced, while flux redistribution between stars and background increases the errors.

Early detection and longitudinal imaging of cancer micrometastases using biofunctionalized rare-earth albumin nanocomposites

NASA Astrophysics Data System (ADS)

Zevon, M.; Kantamneni, H.; Ganapathy, V.; Higgins, L.; Mingozzi, M.; Pierce, M.; Riman, R.; Roth, C. M.; Moghe, P. V.

2016-05-01

Success of personalized medicine in cancer therapy depends on the ability to identify and molecularly phenotype tumors. Current clinical imaging techniques cannot be integrated with precision molecular medicine at the level of single cells or microlesions due to limited resolution. In this work we use molecularly targeted infrared emitting optical probes to identify and characterize metastatic microlesions prior to their detection with clinically relevant imaging modalities. These contrast agents form the basis of an in vivo optical imaging system capable of resolving internal microlesions, filling a critical unmet need in cancer imaging.

Development of a method for the simultaneous determination of multi-class pesticides in earthworms by liquid chromatography coupled to tandem electrospray mass spectrometry.

PubMed

Daniele, Gaëlle; Lafay, Florent; Pelosi, Céline; Fritsch, Clémentine; Vulliet, Emmanuelle

2018-06-04

Agricultural intensification, and in particular the use of pesticides, leads over the years to a loss of biodiversity and a decline of ecosystem services in cultivated zones and agricultural landscapes. Among the animal communities involved in the functioning of agro-ecosystems, earthworms are ubiquitous and recognized as indicators of land uses and cultural practices. However, little data is available on the levels of pesticides in such organisms in natura, which would allow estimating their actual exposure and the potentially resulting impacts. Thus, the objective of this study was to develop a sensitive analytical methodology to detect and quantify 27 currently used pesticides in earthworms (Allolobophora chlorotica). A modified QuEChERS extraction was implemented on individual earthworms. This step was followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The whole analytical method was validated on spiked earthworm blank samples, with regard to linearity (from 1 to 100 method limit of quantification, r 2  > 0.95), intra-day precision (relative standard deviation (RSD) < 15%), inter-day precision (RSD < 20%), recoveries (mainly in the range 70-110%), and limits of detection and of quantification (inferior to 5 ng/g for most of the pesticides). The developed method was successfully applied to determine the concentrations of pesticides in nine individuals collected in natura. Up to five of the selected pesticides have been detected in one individual. Graphical abstract.

Digital PCR provides absolute quantitation of viral load for an occult RNA virus.

PubMed

White, Richard Allen; Quake, Stephen R; Curr, Kenneth

2012-01-01

Using a multiplexed LNA-based Taqman assay, RT-digital PCR (RT-dPCR) was performed in a prefabricated microfluidic device that monitored absolute viral load in native and immortalized cell lines, overall precision of detection, and the absolute detection limit of an occult RNA virus GB Virus Type C (GBV-C). RT-dPCR had on average a 10% lower overall coefficient of variation (CV, a measurement of precision) for viral load testing than RT-qPCR and had a higher overall detection limit, able to quantify as low as three 5'-UTR molecules of GBV-C genome. Two commercial high-yield in vitro transcription kits (T7 Ribomax Express by Promega and Ampliscribe T7 Flash by Epicentre) were compared to amplify GBV-C RNA genome with T7-mediated amplification. The Ampliscribe T7 Flash outperformed the T7 Ribomax Express in yield of full-length GBV-C RNA genome. THP-1 cells (a model of monocytic derived cells) were transfected with GBV-C, yielding infectious virions that replicated over a 120h time course and could be infected directly. This study provides the first evidence of GBV-C replication in monocytic derived clonal cells. Thus far, it is the only study using a microfluidic device that measures directly viral load of mammalian RNA virus in a digital format without need for a standard curve. Copyright © 2011 Elsevier B.V. All rights reserved.

Surveying Nearby M dwarfs with Gaia: A Treasure Trove for Exoplanet Astrophysics

NASA Astrophysics Data System (ADS)

Sozzetti, A.; Tinetti, G.; Lattanzi, M. G.; Micela, G.; Morbidelli, R.; Giacobbe, P.

2011-10-01

Cool, nearby M dwarfs within a few tens of parsecs from the Sun are today becoming the focus of dedicated experiments in the realm of exoplanets astrophysics. This is due to the shift in theoretical paradigms in light of new observations, and thanks to the improved understanding of the observational opportunities for planet detection and characterization provided by this sample. Gaia, in its all-sky survey, will deliver precision astrometry for a magnitude-limited (V=20) sample of M dwarfs in the vicinity of the Sun, providing an inventory of cool nearby stars with a much higher degree of completeness (particularly for late sub-types) with respect to currently available catalogs. We gauge the Gaia potential for precision astrometry of exoplanets orbiting a sample of actual M stars within 30 pc from the Sun. The stellar reservoir is carefully selected based on cross-correlation among catalogs in the literature (e.g., Lepine, PMSU).We express Gaia sensitivity thresholds as a function of system parameters and in view of the latest mission profile, including the most up-to-date astrometric error model. The simulations also provide insight on the capability of high-precision astrometry to reconstruct the underlying orbital elements and mass distributions of the generated companions. We investigate the synergy between the Gaia data on nearby M dwarfs and other ground-based and spaceborne programs for planet detection and characterization, with a particular focus on: a) the improvements in the determination of transiting planet parameters thanks to the exquisitely precise stellar distances determined by Gaia; b) the betterment in orbit modeling when Gaia astrometry and precision radial-velocities are available for the same targets; and c) the ability of Gaia to carefully predict the ephemerides of detected (transiting and non-transiting) planets aroundM stars, for the purpose of spectroscopic characterization of their atmospheres with dedicated observatories in space, such as EChO.

Reverse phase HPLC method for detection and quantification of lupin seed γ-conglutin.

PubMed

Mane, Sharmilee; Bringans, Scott; Johnson, Stuart; Pareek, Vishnu; Utikar, Ranjeet

2017-09-15

A simple, selective and accurate reverse phase HPLC method was developed for detection and quantitation of γ-conglutin from lupin seed extract. A linear gradient of water and acetonitrile containing trifluoroacetic acid (TFA) on a reverse phase column (Agilent Zorbax 300SB C-18), with a flow rate of 0.8ml/min was able to produce a sharp and symmetric peak of γ-conglutin with a retention time at 29.16min. The identity of γ-conglutin in the peak was confirmed by mass spectrometry (MS/MS identification) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The data obtained from MS/MS analysis was matched against the specified database to obtain the exact match for the protein of interest. The proposed method was validated in terms of specificity, linearity, sensitivity, precision, recovery and accuracy. The analytical parameters revealed that the validated method was capable of selectively performing a good chromatographic separation of γ-conglutin from the lupin seed extract with no interference of the matrix. The detection and quantitation limit of γ-conglutin were found to be 2.68μg/ml and 8.12μg/ml respectively. The accuracy (precision and recovery) analysis of the method was conducted under repeatable conditions on different days. Intra-day and inter-day precision values less than 0.5% and recovery greater than 97% indicated high precision and accuracy of the method for analysis of γ-conglutin. The method validation findings were reproducible and can be successfully applied for routine analysis of γ-conglutin from lupin seed extract. Copyright © 2017 Elsevier B.V. All rights reserved.

Liquid electrode plasma-optical emission spectrometry combined with solid-phase preconcentration for on-site analysis of lead.

PubMed

Barua, Suman; Rahman, Ismail M M; Alam, Iftakharul; Miyaguchi, Maho; Sawai, Hikaru; Maki, Teruya; Hasegawa, Hiroshi

2017-08-15

A relatively rapid and precise method is presented for the determination of lead in aqueous matrix. The method consists of analyte quantitation using the liquid electrode plasma-optical emission spectrometry (LEP-OES) coupled with selective separation/preconcentration by solid-phase extraction (SPE). The impact of operating variables on the retention of lead in SPEs such as pH, flow rate of the sample solution; type, volume, flow rate of the eluent; and matrix effects were investigated. Selective SPE-separation/preconcentration minimized the interfering effect due to manganese in solution and limitations in lead-detection in low-concentration samples by LEP-OES. The LEP-OES operating parameters such as the electrical conductivity of sample solution; applied voltage; on-time, off-time, pulse count for applied voltage; number of measurements; and matrix effects have also been optimized to obtain a distinct peak for the lead at λ max =405.8nm. The limit of detection (3σ) and the limit of quantification (10σ) for lead determination using the technique were found as 1.9 and 6.5ng mL -1 , respectively. The precision, as relative standard deviation, was lower than 5% at 0.1μg mL -1 Pb, and the preconcentration factor was found to be 187. The proposed method was applied to the analysis of lead contents in the natural aqueous matrix (recovery rate:>95%). The method accuracy was verified using certified reference material of wastewaters: SPS-WW1 and ERM-CA713. The results from LEP-OES were in good agreement with inductively coupled plasma optical emission spectrometry measurements of the same samples. The application of the method is rapid (≤5min, without preconcentration) with a reliable detection limit at trace levels. Copyright © 2017 Elsevier B.V. All rights reserved.

sFIDA automation yields sub-femtomolar limit of detection for Aβ aggregates in body fluids.

PubMed

Herrmann, Yvonne; Kulawik, Andreas; Kühbach, Katja; Hülsemann, Maren; Peters, Luriano; Bujnicki, Tuyen; Kravchenko, Kateryna; Linnartz, Christina; Willbold, Johannes; Zafiu, Christian; Bannach, Oliver; Willbold, Dieter

2017-03-01

Alzheimer's disease (AD) is a neurodegenerative disorder with yet non-existent therapeutic and limited diagnostic options. Reliable biomarker-based AD diagnostics are of utmost importance for the development and application of therapeutic substances. We have previously introduced a platform technology designated 'sFIDA' for the quantitation of amyloid β peptide (Aβ) aggregates as AD biomarker. In this study we implemented the sFIDA assay on an automated platform to enhance robustness and performance of the assay. In sFIDA (surface-based fluorescence intensity distribution analysis) Aβ species are immobilized by a capture antibody to a glass surface. Aβ aggregates are then multiply loaded with fluorescent antibodies and quantitated by high resolution fluorescence microscopy. As a model system for Aβ aggregates, we used Aβ-conjugated silica nanoparticles (Aβ-SiNaPs) diluted in PBS buffer and cerebrospinal fluid, respectively. Automation of the assay was realized on a liquid handling system in combination with a microplate washer. The automation of the sFIDA assay results in improved intra-assay precision, linearity and sensitivity in comparison to the manual application, and achieved a limit of detection in the sub-femtomolar range. Automation improves the precision and sensitivity of the sFIDA assay, which is a prerequisite for high-throughput measurements and future application of the technology in routine AD diagnostics. Copyright © 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

GAMETES: a fast, direct algorithm for generating pure, strict, epistatic models with random architectures.

PubMed

Urbanowicz, Ryan J; Kiralis, Jeff; Sinnott-Armstrong, Nicholas A; Heberling, Tamra; Fisher, Jonathan M; Moore, Jason H

2012-10-01

Geneticists who look beyond single locus disease associations require additional strategies for the detection of complex multi-locus effects. Epistasis, a multi-locus masking effect, presents a particular challenge, and has been the target of bioinformatic development. Thorough evaluation of new algorithms calls for simulation studies in which known disease models are sought. To date, the best methods for generating simulated multi-locus epistatic models rely on genetic algorithms. However, such methods are computationally expensive, difficult to adapt to multiple objectives, and unlikely to yield models with a precise form of epistasis which we refer to as pure and strict. Purely and strictly epistatic models constitute the worst-case in terms of detecting disease associations, since such associations may only be observed if all n-loci are included in the disease model. This makes them an attractive gold standard for simulation studies considering complex multi-locus effects. We introduce GAMETES, a user-friendly software package and algorithm which generates complex biallelic single nucleotide polymorphism (SNP) disease models for simulation studies. GAMETES rapidly and precisely generates random, pure, strict n-locus models with specified genetic constraints. These constraints include heritability, minor allele frequencies of the SNPs, and population prevalence. GAMETES also includes a simple dataset simulation strategy which may be utilized to rapidly generate an archive of simulated datasets for given genetic models. We highlight the utility and limitations of GAMETES with an example simulation study using MDR, an algorithm designed to detect epistasis. GAMETES is a fast, flexible, and precise tool for generating complex n-locus models with random architectures. While GAMETES has a limited ability to generate models with higher heritabilities, it is proficient at generating the lower heritability models typically used in simulation studies evaluating new algorithms. In addition, the GAMETES modeling strategy may be flexibly combined with any dataset simulation strategy. Beyond dataset simulation, GAMETES could be employed to pursue theoretical characterization of genetic models and epistasis.

Development and practical application of accelerated solvent extraction for the isolation of cocaine/crack biomarkers in meconium samples.

PubMed

Mantovani, Cínthia de Carvalho; Lima, Marcela Bittar; Oliveira, Carolina Dizioli Rodrigues de; Menck, Rafael de Almeida; Diniz, Edna Maria de Albuquerque; Yonamine, Mauricio

2014-04-15

A method using accelerated solvent extraction (ASE) for the isolation of cocaine/crack biomarkers in meconium samples, followed by solid phase extraction (SPE) and the simultaneous quantification by gas chromatography-mass spectrometry (GC-MS) was developed and validated. Initially, meconium samples were submitted to an ASE procedure, which was followed by SPE with Bond Elut Certify I cartridges. The analytes were derivatizated with PFP/PFPA and analyzed by GC-MS. The limits of detection (LOD) were between 11 and 17ng/g for all analytes. The limits of quantification (LOQ) were 30ng/g for anhydroecgonine methyl ester, and 20ng/g for cocaine, benzoylecgonine, ecgonine methyl ester and cocaethylene. Linearity ranged from the LOQ to 1500ng/g for all analytes, with a coefficients of determination greater than 0.991, except for m-hydroxybenzoylecgonine, which was only qualitatively detected. Precision and accuracy were evaluated at three concentration levels. For all analytes, inter-assay precision ranged from 3.2 to 18.1%, and intra-assay precision did not exceed 12.7%. The accuracy results were between 84.5 and 114.2% and the average recovery ranged from 17 to 84%. The method was applied to 342 meconium samples randomly collected in the University Hospital-University of São Paulo (HU-USP), Brazil. Cocaine biomarkers were detected in 19 samples, which represent 5.6% of exposure prevalence. Significantly lower birth weight, length and head circumference were found for the exposed newborns compared with the non-exposed group. This is the first report in which ASE was used as a sample preparation technique to extract cocaine biomarkers from a complex biological matrix such as meconium samples. The advantages of the developed method are the smaller demand for organic solvents and the minor sample handling, which allows a faster and accurate procedure, appropriate to confirm fetal exposure to cocaine/crack. Copyright © 2014 Elsevier B.V. All rights reserved.

Ppb-level mid-infrared ethane detection based on three measurement schemes using a 3.34-μm continuous-wave interband cascade laser

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

Li, Chunguang; Zheng, Chuantao; Dong, Lei

A ppb-level mid-infrared ethane (C 2H 6) sensor was developed using a continuous-wave, thermoelectrically cooled, distributed feedback interband cascade laser emitting at 3.34 μm and a miniature dense patterned multipass gas cell with a 54.6-m optical path length. The performance of the sensor was investigated using two different techniques based on the tunable interband cascade laser: direct absorption spectroscopy (DAS) and second-harmonic wavelength modulation spectroscopy (2f-WMS). Three measurement schemes, DAS, WMS and quasi-simultaneous DAS and WMS, were realized based on the same optical sensor core. A detection limit of ~7.92 ppbv with a precision of ±30 ppbv for the separatemore » DAS scheme with an averaging time of 1 s and a detection limit of ~1.19 ppbv with a precision of about ±4 ppbv for the separate WMS scheme with a 4-s averaging time were achieved. An Allan–Werle variance analysis indicated that the precisions can be further improved to 777 pptv @ 166 s for the separate DAS scheme and 269 pptv @ 108 s for the WMS scheme, respectively. For the quasi-simultaneous DAS and WMS scheme, both the 2f signal and the direct absorption signal were simultaneously extracted using a LabVIEW platform, and four C 2H 6 samples (0, 30, 60 and 90 ppbv with nitrogen as the balance gas) were used as the target gases to assess the sensor performance. A detailed comparison of the three measurement schemes is reported. Here, atmospheric C 2H 6 measurements on the Rice University campus and a field test at a compressed natural gas station in Houston, TX, were conducted to evaluate the performance of the sensor system as a robust and reliable field-deployable sensor system.« less

Ppb-level mid-infrared ethane detection based on three measurement schemes using a 3.34-μm continuous-wave interband cascade laser

DOE PAGES

Li, Chunguang; Zheng, Chuantao; Dong, Lei; ...

2016-06-20

A ppb-level mid-infrared ethane (C 2H 6) sensor was developed using a continuous-wave, thermoelectrically cooled, distributed feedback interband cascade laser emitting at 3.34 μm and a miniature dense patterned multipass gas cell with a 54.6-m optical path length. The performance of the sensor was investigated using two different techniques based on the tunable interband cascade laser: direct absorption spectroscopy (DAS) and second-harmonic wavelength modulation spectroscopy (2f-WMS). Three measurement schemes, DAS, WMS and quasi-simultaneous DAS and WMS, were realized based on the same optical sensor core. A detection limit of ~7.92 ppbv with a precision of ±30 ppbv for the separatemore » DAS scheme with an averaging time of 1 s and a detection limit of ~1.19 ppbv with a precision of about ±4 ppbv for the separate WMS scheme with a 4-s averaging time were achieved. An Allan–Werle variance analysis indicated that the precisions can be further improved to 777 pptv @ 166 s for the separate DAS scheme and 269 pptv @ 108 s for the WMS scheme, respectively. For the quasi-simultaneous DAS and WMS scheme, both the 2f signal and the direct absorption signal were simultaneously extracted using a LabVIEW platform, and four C 2H 6 samples (0, 30, 60 and 90 ppbv with nitrogen as the balance gas) were used as the target gases to assess the sensor performance. A detailed comparison of the three measurement schemes is reported. Here, atmospheric C 2H 6 measurements on the Rice University campus and a field test at a compressed natural gas station in Houston, TX, were conducted to evaluate the performance of the sensor system as a robust and reliable field-deployable sensor system.« less

Validation of a rapid micellar electrokinetic capillary chromatographic method for the simultaneous determination of isoniazid and pyridoxine hydrochloride in pharmaceutical formulation.

PubMed

Nemutlu, E; Celebier, M; Uyar, B; Altinöz, S

2007-07-01

An efficient and reliable micellar electrokinetic capillary chromatography (MEKC) method has been developed for the simultaneous determination of isoniazid (ISO) and pyridoxine hydrochloride (PYR) in pharmaceutical formulations. A chemometric two level full factorial design approach was used to search for the optimum conditions of separation. Three parameters were selected for this study: the buffer pH, the buffer concentration and sodium dodecyl sulphate (SDS) concentrations. Resolution, peak symmetry and analysis time were established as response. The two analytes were separated within 6 min with the optimized conditions: 50 mM borate buffer, 25 mM SDS pH 7.8, 35 degrees C, at 50 mbar 4s injection and 30 kV by using a fused silica capillary (72 cm effective length, 50 microm i.d.). The detection wavelength was set to 205 nm. Meloxicam was used as internal standard. The method was validated with respect to stability, linearity range, limit of quantitation and detection, precision, accuracy, specificity and robustness. The detection limits of the method were 1.0 microg mL(-1) for ISO and 0.40 microg mL(-1) for PYR and the method was linear at least in the range of 3.0-100 microg mL(-1) for ISO and 1.0-100 microg mL(-1) for PYR with excellent correlation coefficients (0.9995 for ISO and 0.9998 for PYR). Relative standard deviations (R.S.D.s) of the described method ranged between 0.54 and 2.27% for intra-day precision and between 0.65 and 2.69% for inter-day precision. The developed method was applied to the tablet form of ISO and PYR-containing the pharmaceutical preparations and the data were compared with obtained from the standard addition method. No statistically significant difference was found.

Comparison of the Detection Characteristics of Trace Species Using Laser-Induced Breakdown Spectroscopy and Laser Breakdown Time-of-Flight Mass Spectrometry

PubMed Central

Wang, Zhenzhen; Deguchi, Yoshihiro; Yan, Junjie; Liu, Jiping

2015-01-01

The rapid and precise element measurement of trace species, such as mercury, iodine, strontium, cesium, etc. is imperative for various applications, especially for industrial needs. The elements mercury and iodine were measured by two detection methods for comparison of the corresponding detection features. A laser beam was focused to induce plasma. Emission and ion signals were detected using laser-induced breakdown spectroscopy (LIBS) and laser breakdown time-of-flight mass spectrometry (LB-TOFMS). Multi-photon ionization and electron impact ionization in the plasma generation process can be controlled by the pressure and pulse width. The effect of electron impact ionization on continuum emission, coexisting molecular and atomic emissions became weakened in low pressure condition. When the pressure was less than 1 Pa, the plasma was induced by laser dissociation and multi-photon ionization in LB-TOFMS. According to the experimental results, the detection limits of mercury and iodine in N2 were 3.5 ppb and 60 ppb using low pressure LIBS. The mercury and iodine detection limits using LB-TOFMS were 1.2 ppb and 9.0 ppb, which were enhanced due to different detection features. The detection systems of LIBS and LB-TOFMS can be selected depending on the condition of each application. PMID:25769051

Video-rate or high-precision: a flexible range imaging camera

NASA Astrophysics Data System (ADS)

Dorrington, Adrian A.; Cree, Michael J.; Carnegie, Dale A.; Payne, Andrew D.; Conroy, Richard M.; Godbaz, John P.; Jongenelen, Adrian P. P.

2008-02-01

A range imaging camera produces an output similar to a digital photograph, but every pixel in the image contains distance information as well as intensity. This is useful for measuring the shape, size and location of objects in a scene, hence is well suited to certain machine vision applications. Previously we demonstrated a heterodyne range imaging system operating in a relatively high resolution (512-by-512) pixels and high precision (0.4 mm best case) configuration, but with a slow measurement rate (one every 10 s). Although this high precision range imaging is useful for some applications, the low acquisition speed is limiting in many situations. The system's frame rate and length of acquisition is fully configurable in software, which means the measurement rate can be increased by compromising precision and image resolution. In this paper we demonstrate the flexibility of our range imaging system by showing examples of high precision ranging at slow acquisition speeds and video-rate ranging with reduced ranging precision and image resolution. We also show that the heterodyne approach and the use of more than four samples per beat cycle provides better linearity than the traditional homodyne quadrature detection approach. Finally, we comment on practical issues of frame rate and beat signal frequency selection.

Detection of active transposable elements in Arabidopsis thaliana using Oxford Nanopore Sequencing technology.

PubMed

Debladis, Emilie; Llauro, Christel; Carpentier, Marie-Christine; Mirouze, Marie; Panaud, Olivier

2017-07-17

Transposables elements (TEs) contribute to both structural and functional dynamics of most eukaryotic genomes. Because of their propensity to densely populate plant and animal genomes, the precise estimation of the impact of transposition on genomic diversity has been considered as one of the main challenges of today's genomics. The recent development of NGS (next generation sequencing) technologies has open new perspectives in population genomics by providing new methods for high throughput detection of Transposable Elements-associated Structural Variants (TEASV). However, these have relied on Illumina platform that generates short reads (up to 350 nucleotides). This limitation in size of sequence reads can cause high false discovery rate (FDR) and therefore limit the power of detection of TEASVs, especially in the case of large, complex genomes. The newest sequencing technologies, such as Oxford Nanopore Technologies (ONT) can generate kilobases-long reads thus representing a promising tool for TEASV detection in plant and animals. We present the results of a pilot experiment for TEASV detection on the model plant species Arabidopsis thaliana using ONT sequencing and show that it can be used efficiently to detect TE movements. We generated a ~0.8X genome coverage of a met1-derived epigenetic recombinant inbred line (epiRIL) using a MinIon device with R7 chemistry. We were able to detect nine new copies of the LTR-retrotransposon Evadé (EVD). We also evidenced the activity of the DNA transposon CACTA, CAC1. Even at a low sequence coverage (0.8X), ONT sequencing allowed us to reliably detect several TE insertions in Arabidopsis thaliana genome. The long read length allowed a precise and un-ambiguous mapping of the structural variations caused by the activity of TEs. This suggests that the trade-off between read length and genome coverage for TEASV detection may be in favor of the former. Should the technology be further improved both in terms of lower error rate and operation costs, it could be efficiently used in diversity studies at population level.

An environmentally-friendly, highly efficient, gas pressure-assisted sample introduction system for ICP-MS and its application to detection of cadmium and lead in human plasma.

PubMed

Cao, Yupin; Deng, Biyang; Yan, Lizhen; Huang, Hongli

2017-05-15

An environmentally friendly and highly efficient gas pressure-assisted sample introduction system (GPASIS) was developed for inductively-coupled plasma mass spectrometry. A GPASIS consisting of a gas-pressure control device, a customized nebulizer, and a custom-made spray chamber was fabricated. The advantages of this GPASIS derive from its high nebulization efficiencies, small sample volume requirements, low memory effects, good precision, and zero waste emission. A GPASIS can continuously, and stably, nebulize 10% NaCl solution for more than an hour without clogging. Sensitivity, detection limits, precision, long-term stability, double charge and oxide ion levels, nebulization efficiencies, and matrix effects of the sample introduction system were evaluated. Experimental results indicated that the performance of this GPASIS, was equivalent to, or better than, those obtained by conventional sample introduction systems. This GPASIS was successfully used to determine Cd and Pb by ICP-MS in human plasma. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of three steroidal saponins from Ophiopogon japonicus (Liliaceae) via high-performance liquid chromatography with mass spectrometry.

PubMed

Wang, Yongyi; Xu, Jinzhong; Qu, Haibin

2013-01-01

A simple and accurate analytical method was developed for simultaneous quantification of three steroidal saponins in the roots of Ophiopogon japonicus via high-performance liquid chromatography (HPLC) with mass spectrometry (MS) in this study. Separation was performed on a Tigerkin C(18) column and detection was performed by mass spectrometry. A mobile phase consisted of 0.02% formic acid in water (v/v) and 0.02% formic acid in acetonitrile (v/v) was used with a flow rate of 0.5 mL min(-1). The quantitative HPLC-MS method was validated for linearity, precision, repeatability, stability, recovery, limits of detection and quantification. This developed method provides good linearity (r >0.9993), intra- and inter-day precisions (RSD <4.18%), repeatability (RSD <5.05%), stability (RSD <2.08%) and recovery (93.82-102.84%) for three steroidal saponins. It could be considered as a suitable quality control method for O. japonicus.

Rapid method for the determination of 14 isoflavones in food using UHPLC coupled to photo diode array detection.

PubMed

Shim, You-Shin; Yoon, Won-Jin; Hwang, Jin-Bong; Park, Hyun-Jin; Seo, Dongwon; Ha, Jaeho

2015-11-15

A rapid method for the determination of 14 types of isoflavones in food using ultra-high performance liquid chromatography (UHPLC) was validated in terms of precision, accuracy, sensitivity and linearity. The UHPLC separation was performed on a reverse-phase C18 column (particle size 2 μm, i.d. 2 mm, length 100 mm) using a photo diode array detector that was fixed to 260 nm. The limits of detection and quantification of the UHPLC analyses ranged from 0.03 to 0.33 mg kg(-1). The intra-day and inter-day precision of the individual isoflavones were less than 11.77% and calibration curves exhibited good linearity (r(2) = 0.99) within the tested ranges. These results suggest that the rapid method used in this study could be available to determine of 14 types of isoflavones in a variety of food such as soy bean, black bean, red bean and soybean paste. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ppb-level formaldehyde detection using a CW room-temperature interband cascade laser and a miniature dense pattern multipass gas cell

DOE PAGES

Dong, Lei; Yu, Yajun; Li, Chunguang; ...

2015-07-27

A ppb-level formaldehyde (H 2CO) sensor was developed using a thermoelectrically cooled (TEC), continuous-wave (CW) room temperature interband cascade laser (ICL) emitting at 3.59 μm and a miniature dense pattern multipass gas cell with >50 m optical path length. Performance of the sensor was investigated with two measurement schemes: direct absorption (DAS) and wavelength modulation spectroscopy (WMS). With an integration time of less than 1.5 second, a detection limit of ~3 ppbv for H 2CO measurement with precision of 1.25 ppbv for DAS and 0.58 ppbv for WMS, respectively, was achieved without zero air based background subtraction. An Allan-Werle variancemore » analysis indicated that the precisions can be further improved to 0.26 ppbv @ 300s for DAS and 69 pptv @ 90 s for WMS, respectively. Finally, a side-by-side comparison between two measurement schemes is also discussed in detail.« less

Prenatal diagnosis in a cystic fibrosis family: a combined molecular strategy for a precise diagnosis.

PubMed

Chávez-Saldaña, Margarita; García-Cavazos, Ricardo; Vigueras, Rosa María; Orozco, Lorena

2011-01-01

The high genetic heterogeneity in populations with a wide spectrum of mutations in the CF transmembrane conductance regulator gene (CFTR), makes the detection of mutations a very hard and difficult task, thereby limiting the accurate diagnosis of the disease, mainly in patients with uncharacterized mutations. Molecular strategies, like targeted identification of the most frequent CFTR mutations in Mexican population combined with linkage analysis using markers, is very useful for carrier detection and for prenatal diagnosis in affected families with CF. In this paper we show that the combination of methodologies was a crucial alternative to reach a precise prenatal CF diagnosis. We documented CF diagnosis in a 14th-week fetus combining the screening of the most common mutations in Mexican population with linkage analysis of two extragenic polymorphisms (XV2C/TaqI and KM19/PstI). We determined that the fetus inherited the PG542X mutation from its mother and an unknown mutation from its father through the chromosomal phases analysis.

Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

PubMed

Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

2014-01-01

A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples. Copyright © 2014 Elsevier Inc. All rights reserved.

Direction information in multiple object tracking is limited by a graded resource.

PubMed

Horowitz, Todd S; Cohen, Michael A

2010-10-01

Is multiple object tracking (MOT) limited by a fixed set of structures (slots), a limited but divisible resource, or both? Here, we answer this question by measuring the precision of the direction representation for tracked targets. The signature of a limited resource is a decrease in precision as the square root of the tracking load. The signature of fixed slots is a fixed precision. Hybrid models predict a rapid decrease to asymptotic precision. In two experiments, observers tracked moving disks and reported target motion direction by adjusting a probe arrow. We derived the precision of representation of correctly tracked targets using a mixture distribution analysis. Precision declined with target load according to the square-root law up to six targets. This finding is inconsistent with both pure and hybrid slot models. Instead, directional information in MOT appears to be limited by a continuously divisible resource.

Sensitive Precise p H Measurement with Large-Area Graphene Field-Effect Transistors at the Quantum-Capacitance Limit

NASA Astrophysics Data System (ADS)

Fakih, Ibrahim; Mahvash, Farzaneh; Siaj, Mohamed; Szkopek, Thomas

2017-10-01

A challenge for p H sensing is decreasing the minimum measurable p H per unit bandwidth in an economical fashion. Minimizing noise to reach the inherent limit imposed by charge fluctuation remains an obstacle. We demonstrate here graphene-based ion-sensing field-effect transistors that saturate the physical limit of sensitivity, defined here as the change in electrical response with respect to p H , and achieve a precision limited by charge-fluctuation noise at the sensing layer. We present a model outlining the necessity for maximizing the device carrier mobility, active sensing area, and capacitive coupling in order to minimize noise. We encapsulate large-area graphene with an ultrathin layer of parylene, a hydrophobic polymer, and deposit an ultrathin, stoichiometric p H -sensing layer of either aluminum oxide or tantalum pentoxide. With these structures, we achieve gate capacitances ˜0.6 μ F /cm2 , approaching the quantum-capacitance limit inherent to graphene, along with a near-Nernstian p H response of ˜55 ±2 mV /p H . We observe field-effect mobilities as high as 7000 cm2 V-1 s-1 with minimal hysteresis as a result of the parylene encapsulation. A detection limit of 0.1 m p H in a 60-Hz electrical bandwidth is observed in optimized graphene transistors.

Study of gamma detection capabilities of the REWARD mobile spectroscopic system

NASA Astrophysics Data System (ADS)

Balbuena, J. P.; Baptista, M.; Barros, S.; Dambacher, M.; Disch, C.; Fiederle, M.; Kuehn, S.; Parzefall, U.

2017-07-01

REWARD is a novel mobile spectroscopic radiation detector system for Homeland Security applications. The system integrates gamma and neutron detection equipped with wireless communication. A comprehensive simulation study on its gamma detection capabilities in different radioactive scenarios is presented in this work. The gamma detection unit consists of a precise energy resolution system based on two stacked (Cd,Zn)Te sensors working in coincidence sum mode. The volume of each of these CZT sensors is 1 cm3. The investigated energy windows used to determine the detection capabilities of the detector correspond to the gamma emissions from 137Cs and 60Co radioactive sources (662 keV and 1173/1333 keV respectively). Monte Carlo and Technology Computer-Aided Design (TCAD) simulations are combined to determine its sensing capabilities for different radiation sources and estimate the limits of detection of the sensing unit as a function of source activity for several shielding materials.

Measuring xenon in human plasma and blood by gas chromatography/mass spectrometry.

PubMed

Thevis, Mario; Piper, Thomas; Geyer, Hans; Thomas, Andreas; Schaefer, Maximilian S; Kienbaum, Peter; Schänzer, Wilhelm

2014-07-15

Due to the favorable pharmacokinetic properties and minimal side effects of xenon, its use in modern anesthesia has been well accepted, and recent studies further demonstrated the intra- and postoperative neuro-, cardio-, and reno-protective action of the noble gas. Since the production of the hypoxia-inducible factor 1α (HIF-1α) and its downstream effector erythropoietin as well as noradrenalin reuptake inhibition have been found to play key roles in this context, the question arose as to whether the use of xenon is a matter for doping controls and preventive doping research. The aim of the present study was hence to evaluate whether the (ab)use of xenon can be detected from doping control samples with the instrumentation commonly available in sports drug testing laboratories. Plasma was saturated with xenon according to reported protocols, and the target analyte was measured by means of gas chromatography/time-of-flight and triple quadrupole mass spectrometry with headspace injection. Recording the accurate mass of three major xenon isotopes at m/z 128.9048, 130.9045 and 131.9042 allowed for the unequivocal identification of the analyte and the detection assay was characterized concerning limit of detection (LOD), intraday precision, and specificity as well as analyte recovery under different storage conditions. Xenon was detected in fortified plasma samples with detection limits of approximately 0.5 nmol/mL to 50 nmol/mL, depending on the type of mass spectrometer used. The method characteristics of intraday precision (coefficient of variation <20%) and specificity demonstrated the fitness-for-purpose of the analytical approach to unambiguously detect xenon at non-physiological concentrations in human plasma and blood. Eventually, authentic plasma and blood samples collected pre-, intra-, and post-operative (4, 8, and 24 h) were positively analyzed after storage for up to 30 h, and provided proof-of-concept for the developed assay. If relevant to doping controls, xenon can be determined from plasma and blood samples, i.e. common specimens of routine sports drug testing in the context of Athlete Biological Passport (ABP) analyses. Optimization of sampling and analytical procedures will allow the detection limit to be further improved and potentially enable accurate quantification of the anesthetic agent. Copyright © 2014 John Wiley & Sons, Ltd.

Detection of BCG bacteria using a magnetoresistive biosensor: A step towards a fully electronic platform for tuberculosis point-of-care detection.

PubMed

Barroso, Teresa G; Martins, Rui C; Fernandes, Elisabete; Cardoso, Susana; Rivas, José; Freitas, Paulo P

2018-02-15

Tuberculosis is one of the major public health concerns. This highly contagious disease affects more than 10.4 million people, being a leading cause of morbidity by infection. Tuberculosis is diagnosed at the point-of-care by the Ziehl-Neelsen sputum smear microscopy test. Ziehl-Neelsen is laborious, prone to human error and infection risk, with a limit of detection of 10 4 cells/mL. In resource-poor nations, a more practical test, with lower detection limit, is paramount. This work uses a magnetoresistive biosensor to detect BCG bacteria for tuberculosis diagnosis. Herein we report: i) nanoparticle assembly method and specificity for tuberculosis detection; ii) demonstration of proportionality between BCG cell concentration and magnetoresistive voltage signal; iii) application of multiplicative signal correction for systematic effects removal; iv) investigation of calibration effectiveness using chemometrics methods; and v) comparison with state-of-the-art point-of-care tuberculosis biosensors. Results present a clear correspondence between voltage signal and cell concentration. Multiplicative signal correction removes baseline shifts within and between biochip sensors, allowing accurate and precise voltage signal between different biochips. The corrected signal was used for multivariate regression models, which significantly decreased the calibration standard error from 0.50 to 0.03log 10 (cells/mL). Results show that Ziehl-Neelsen detection limits and below are achievable with the magnetoresistive biochip, when pre-processing and chemometrics are used. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of dasatinib in the tablet dosage form by ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis.

PubMed

Gonzalez, Aroa Garcia; Taraba, Lukáš; Hraníček, Jakub; Kozlík, Petr; Coufal, Pavel

2017-01-01

Dasatinib is a novel oral prescription drug proposed for treating adult patients with chronic myeloid leukemia. Three analytical methods, namely ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis, were developed, validated, and compared for determination of the drug in the tablet dosage form. The total analysis time of optimized ultra high performance liquid chromatography and capillary zone electrophoresis methods was 2.0 and 2.2 min, respectively. Direct ultraviolet detection with detection wavelength of 322 nm was employed in both cases. The optimized sequential injection analysis method was based on spectrophotometric detection of dasatinib after a simple colorimetric reaction with folin ciocalteau reagent forming a blue-colored complex with an absorbance maximum at 745 nm. The total analysis time was 2.5 min. The ultra high performance liquid chromatography method provided the lowest detection and quantitation limits and the most precise and accurate results. All three newly developed methods were demonstrated to be specific, linear, sensitive, precise, and accurate, providing results satisfactorily meeting the requirements of the pharmaceutical industry, and can be employed for the routine determination of the active pharmaceutical ingredient in the tablet dosage form. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estimate of within population incremental selection through branch imbalance in lineage trees

PubMed Central

Liberman, Gilad; Benichou, Jennifer I.C.; Maman, Yaakov; Glanville, Jacob; Alter, Idan; Louzoun, Yoram

2016-01-01

Incremental selection within a population, defined as limited fitness changes following mutation, is an important aspect of many evolutionary processes. Strongly advantageous or deleterious mutations are detected using the synonymous to non-synonymous mutations ratio. However, there are currently no precise methods to estimate incremental selection. We here provide for the first time such a detailed method and show its precision in multiple cases of micro-evolution. The proposed method is a novel mixed lineage tree/sequence based method to detect within population selection as defined by the effect of mutations on the average number of offspring. Specifically, we propose to measure the log of the ratio between the number of leaves in lineage trees branches following synonymous and non-synonymous mutations. The method requires a high enough number of sequences, and a large enough number of independent mutations. It assumes that all mutations are independent events. It does not require of a baseline model and is practically not affected by sampling biases. We show the method's wide applicability by testing it on multiple cases of micro-evolution. We show that it can detect genes and inter-genic regions using the selection rate and detect selection pressures in viral proteins and in the immune response to pathogens. PMID:26586802

Rapid Detection of Human Immunodeficiency Virus Types 1 and 2 by Use of an Improved Piezoelectric Biosensor

PubMed Central

Severns, Virginia; Branch, Darren W.; Edwards, Thayne L.; Larson, Richard S.

2013-01-01

Disasters can create situations in which blood donations can save lives. However, in emergency situations and when resources are depleted, on-site blood donations require the rapid and accurate detection of blood-borne pathogens, including human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). Techniques such as PCR and antibody capture by an enzyme-linked immunosorbent assay (ELISA) for HIV-1 and HIV-2 are precise but time-consuming and require sophisticated equipment that is not compatible with emergency point-of-care requirements. We describe here a prototype biosensor based on piezoelectric materials functionalized with specific antibodies against HIV-1 and HIV-2. We show the rapid and accurate detection of HIV-1 and HIV-2 in both simple and complex solutions, including human serum, and in the presence of a cross-confounding virus. We report detection limits of 12 50% tissue culture infective doses (TCID50s) for HIV-1 and 87 TCID50s for HIV-2. The accuracy, precision of measurements, and operation of the prototype biosensor compared favorably to those for nucleic acid amplification. We conclude that the biosensor has significant promise as a successful point-of-care diagnostic device for use in emergency field applications requiring rapid and reliable testing for blood-borne pathogens. PMID:23515541

Improved quality control of [18F]fluoromethylcholine.

PubMed

Nader, Michael; Reindl, Dietmar; Eichinger, Reinhard; Beheshti, Mohsen; Langsteger, Werner

2011-11-01

With respect to the broad application of [(18)F-methyl]fluorocholine (FCH), there is a need for a safe, but also efficient and convenient way for routine quality control of FCH. Therefore, a GC- method should be developed and validated which allows the simultaneous quantitation of all chemical impurities and residual solvents such as acetonitrile, ethanol, dibromomethane and N,N-dimethylaminoethanol. Analytical GC has been performed with a GC-capillary column Optima 1701 (50 m×0.32 mm), and a pre-column deactivated capillary column phenyl-Sil (10 m×0.32) in line with a flame ionization detector (FID) was used. The validation includes the following tests: specificity, range, accuracy, linearity, precision, limit of detection (LOD) and limit of quantitation (LOQ) of all listed substances. The described GC method has been successfully used for the quantitation of the listed chemical impurities. The specificity of the GC separation has been proven by demonstrating that the appearing peaks are completely separated from each other and that a resolution R≥1.5 for the separation of the peaks could be achieved. The specified range confirmed that the analytical procedure provides an acceptable degree of linearity, accuracy and precision. For each substance, a range from 2% to 120% of the specification limit could be demonstrated. The corresponding LOD values were determined and were much lower than the specification limits. An efficient and convenient GC method for the quality control of FCH has been developed and validated which meets all acceptance criteria in terms of linearity, specificity, precision, accuracy, LOD and LOQ. Copyright © 2011 Elsevier Inc. All rights reserved.

Determination of selected anions in water by ion chromatography

USGS Publications Warehouse

Fishman, Marvin J.; Pyen, Grace

1979-01-01

Ion chromatography is a rapid, sensitive, precise, and accurate method for the determination of major anions in rain water and surface waters. Simultaneous analyses of a single sample for bromide, chloride, fluoride, nitrate, nitrite, orthophosphate, and sulfate require approximately 20 minutes to obtain a chromatogram.Minimum detection limits range from 0.01 milligrams per liter for fluoride to 0.20 milligrams per liter for chloride and sulfate. Percent relative standard deviations were less than nine percent for all anions except nitrite in Standard Reference Water Samples. Only one reference sample contained nitrite and its concentration was near the minimum level of detection. Similar precision was found for chloride, nitrate, and sulfate at concentrations less than 5 milligrams per liter in rainfall samples. Precision for fluoride ranged from 12 to 22 percent, but is attributed to the low concentrations in these samples. The other anions were not detected.To determine accuracy of results, several samples were spiked with known concentrations of fluoride, chloride, nitrate, and sulfate; recoveries ranged from 96 to 103 percent. Known amounts of bromide and phosphate were added, separately, to several other waters, which contained bromide or phosphate. Recovery of added bromide and phosphate ranged from approximately 95 to 104 percent. No recovery data were obtained for nitrite.Chloride, nitrate, nitrite, orthophosphate, and sulfate, in several samples, were also determined independently by automated colorimetric procedures. An automated ion-selective electrode method was used to determine fluoride. Results are in agreement with results obtained by ion chromatography.

A newly validated high-performance liquid chromatography method with diode array ultraviolet detection for analysis of the antimalarial drug primaquine in the blood plasma.

PubMed

Carmo, Ana Paula Barbosa do; Borborema, Manoella; Ribeiro, Stephan; De-Oliveira, Ana Cecilia Xavier; Paumgartten, Francisco Jose Roma; Moreira, Davyson de Lima

2017-01-01

Primaquine (PQ) diphosphate is an 8-aminoquinoline antimalarial drug with unique therapeutic properties. It is the only drug that prevents relapses of Plasmodium vivax or Plasmodium ovale infections. In this study, a fast, sensitive, cost-effective, and robust method for the extraction and high-performance liquid chromatography with diode array ultraviolet detection (HPLC-DAD-UV ) analysis of PQ in the blood plasma was developed and validated. After plasma protein precipitation, PQ was obtained by liquid-liquid extraction and analyzed by HPLC-DAD-UV with a modified-silica cyanopropyl column (250mm × 4.6mm i.d. × 5μm) as the stationary phase and a mixture of acetonitrile and 10mM ammonium acetate buffer (pH = 3.80) (45:55) as the mobile phase. The flow rate was 1.0mL·min-1, the oven temperature was 50OC, and absorbance was measured at 264nm. The method was validated for linearity, intra-day and inter-day precision, accuracy, recovery, and robustness. The detection (LOD) and quantification (LOQ) limits were 1.0 and 3.5ng·mL-1, respectively. The method was used to analyze the plasma of female DBA-2 mice treated with 20mg.kg-1 (oral) PQ diphosphate. By combining a simple, low-cost extraction procedure with a sensitive, precise, accurate, and robust method, it was possible to analyze PQ in small volumes of plasma. The new method presents lower LOD and LOQ limits and requires a shorter analysis time and smaller plasma volumes than those of previously reported HPLC methods with DAD-UV detection. The new validated method is suitable for kinetic studies of PQ in small rodents, including mouse models for the study of malaria.

Performance of the cobas Hepatitis B virus (HBV) test using the cobas 4800 system and comparison of HBV DNA quantification ability between the COBAS AmpliPrep/COBAS TaqMan HBV test version 2.0 and cobas HBV test.

PubMed

Shin, Kyung-Hwa; Lee, Hyun-Ji; Chang, Chulhun L; Kim, Hyung-Hoi

2018-04-01

Hepatitis B virus (HBV) DNA levels are used to predict the response to therapy, determine therapy initiation, monitor resistance to therapy, and establish treatment success. To verify the performance of the cobas HBV test using the cobas 4800 system for HBV DNA quantification and to compare the HBV DNA quantification ability between the cobas HBV test and COBAS AmpliPrep/COBAS TaqMan HBV version 2.0 (CAP/CTM v2.0). The precision, linearity, and limit of detection of the cobas HBV test were evaluated using the 4th World Health Organization International Standard material and plasma samples. Clinical samples that yielded quantitative results using the CAP/CTM v2.0 and cobas HBV tests were subjected to correlational analysis. Three hundred forty-nine samples were subjected to correlational analysis, among which 114 samples showed results above the lower limit of quantification. Comparable results were obtained ([cobas HBV test] = 1.038 × [CAP/CTM v2.0]-0.173, r = 0.914) in 114 samples, which yielded values above the lower limit of quantification. The results for 86.8% of the samples obtained using the cobas HBV test were within 0.5 log 10 IU/mL of the CAP/CTM v2.0 results. The total precision values against the low and high positive controls were 1.4% (mean level: 2.25 log 10 IU/mL) and 3.2% (mean level: 6.23 log 10 IU/mL), respectively. The cobas HBV test demonstrated linearity (1.15-6.75 log 10 IU/mL, y = 0.95 × 6 + 0.17, r 2  = 0.994). The cobas HBV test showed good correlation with CAP/CTM v2.0, and had good precision and an acceptable limit of detection. The cobas HBV test using the cobas 4800 is a reliable method for quantifying HBV DNA levels in the clinical setting. Copyright © 2018. Published by Elsevier B.V.

Far-infrared photometry of compact extragalactic objects - Detection of 3C 345

NASA Technical Reports Server (NTRS)

Harvey, P. M.; Wilking, B. A.; Joy, M.

1982-01-01

The first detection of a quasar between 10 and 1000 microns is reported. The observation permits (1) the determination of the intersection of the optical/infrared and millimeter continua; (2) more precise determination of the total luminosity; (3) the placing of limits on the contribution of any thermal dust emission to the total luminosity. The quasar is the first object ever to have been observed whose energy distribution peaks at wavelength of about 100 microns without a large contribution to the total luminosity from thermal dust emission. The observed flux density of 2.2 + or - 0.5 Jy at 100 microns and an upper limit of 0.5 + or - 0.6 Jy at 50 microns clearly define the overall energy distribution and show the quasar to be a powerful far-infrared source.

Is biomedical nuclear magnetic resonance limited by a revisitable paradigm in physics?

PubMed

de Certaines, J D

2005-12-14

The history of nuclear magnetic resonance (NMR) can be divided generally into two phases: before the Second World War, molecular beam methods made it possible to detect the whole set of spins. However, these methods were destructive for the sample and had a very low precision. The publications of F. Bloch and E. Purcell in 1946 opened up a second phase for NMR with the study of condensed matter, but at the expense of an enormous loss in theoretical sensitivity. During more than half a century, the method of Bloch and Purcell, based on inductive detection of the NMR signal, has allowed many developments in biomedicine. But, curiously, this severely constraining limitation on sensitivity has not been called into question during this half-century, as if the pioneers of the pre-war period had been forgotten.

Rapid Surface Enhanced Raman Scattering (SERS) Detection of Sibutramine Hydrochloride in Pharmaceutical Capsules with a β-Cyclodextrin- Ag/Polyvivnyl Alcohol Hydrogel Substrate.

PubMed

Ouyang, Lei; Jiang, Zuyan; Wang, Nan; Zhu, Lihua; Tang, Heqing

2017-07-10

Sibutramine hydrochloride (SH) is a banned weight-loss drug, but its illegal addition to health products is still rampant. This suggests a very urgent need for a fast and precise detection method for SH. Surface Enhanced Raman Scattering (SERS) is a promising candidate for this purpose, but the weak affinity between SH and bare metal limits its direct SERS detection. In the present work, β-cyclodextrin was capped in situ onto the surface of Ag nanoparticles to function as a scaffold to capture SH. The obtained Ag nanoparticles were encapsulated into polyvinyl alcohol (PVA) to fabricate a SERS active hydrogel with excellent reproducibility. A facile SERS strategy based on such substrate was proposed for trace SH quantification with a linear range of 7.0-150.0 µg·mL -1 , and a detection limit low to 3.0 µg·mL -1 . It was applied to analyze seven types of commercial slimming capsules with satisfactory results, showing good prospect for real applications.

Rapid Surface Enhanced Raman Scattering (SERS) Detection of Sibutramine Hydrochloride in Pharmaceutical Capsules with a β-Cyclodextrin- Ag/Polyvivnyl Alcohol Hydrogel Substrate

PubMed Central

Ouyang, Lei; Jiang, Zuyan; Wang, Nan; Zhu, Lihua; Tang, Heqing

2017-01-01

Sibutramine hydrochloride (SH) is a banned weight-loss drug, but its illegal addition to health products is still rampant. This suggests a very urgent need for a fast and precise detection method for SH. Surface Enhanced Raman Scattering (SERS) is a promising candidate for this purpose, but the weak affinity between SH and bare metal limits its direct SERS detection. In the present work, β-cyclodextrin was capped in situ onto the surface of Ag nanoparticles to function as a scaffold to capture SH. The obtained Ag nanoparticles were encapsulated into polyvinyl alcohol (PVA) to fabricate a SERS active hydrogel with excellent reproducibility. A facile SERS strategy based on such substrate was proposed for trace SH quantification with a linear range of 7.0–150.0 µg·mL–1, and a detection limit low to 3.0 µg·mL−1. It was applied to analyze seven types of commercial slimming capsules with satisfactory results, showing good prospect for real applications. PMID:28698502

Precision spectroscopy of the 2S-4P transition in atomic hydrogen

NASA Astrophysics Data System (ADS)

Maisenbacher, Lothar; Beyer, Axel; Matveev, Arthur; Grinin, Alexey; Pohl, Randolf; Khabarova, Ksenia; Kolachevsky, Nikolai; Hänsch, Theodor W.; Udem, Thomas

2017-04-01

Precision measurements of atomic hydrogen have long been successfully used to extract fundamental constants and to test bound-state QED. However, both these applications are limited by measurements of hydrogen lines other than the very precisely known 1S-2S transition. Moreover, the proton r.m.s.charge radius rp extracted from electronic hydrogen measurements currently disagrees by 4 σ with the much more precise value extracted from muonic hydrogen spectroscopy. We have measured the 2S-4P transition in atomic hydrogen using a cryogenic beam of hydrogen atoms optically excited to the initial 2S state. The first order Doppler shift of the one-photon 2S-4P transition is suppressed by actively stabilized counter-propagating laser beams and time-of-flight resolved detection. Quantum interference between excitation paths can lead to significant line distortions in our system. We use an experimentally verified, simple line shape model to take these distortions into account. With this, we can extract a new value for rp and the Rydberg constant R∞ with comparable accuracy as the combined previous H world data.

Development and validation of an LC-UV method for the determination of sulfonamides in animal feeds.

PubMed

Kumar, P; Companyó, R

2012-05-01

A simple LC-UV method was developed for the determination of residues of eight sulfonamides (sulfachloropyridazine, sulfadiazine, sulfadimidine, sulfadoxine, sulfamethoxypyridazine, sulfaquinoxaline, sulfamethoxazole, and sulfadimethoxine) in six types of animal feed. C18, Oasis HLB, Plexa and Plexa PCX stationary phases were assessed for the clean-up step and the latter was chosen as it showed greater efficiency in the clean-up of interferences. Feed samples spiked with sulfonamides at 2 mg/kg were used to assess the trueness (recovery %) and precision of the method. Mean recovery values ranged from 47% to 66%, intra-day precision (RSD %) from 4% to 15% and inter-day precision (RSD %) from 7% to 18% in pig feed. Recoveries and intra-day precisions were also evaluated in rabbit, hen, cow, chicken and piglet feed matrices. Calibration curves with standards prepared in mobile phase and matrix-matched calibration curves were compared and the matrix effects were ascertained. The limits of detection and quantification in the feeds ranged from 74 to 265 µg/kg and from 265 to 868 µg/kg, respectively. Copyright © 2011 John Wiley & Sons, Ltd.

A high-throughput LC-MS/MS screen for GHRP in equine and human urine, featuring peptide derivatization for improved chromatography.

PubMed

Timms, Mark; Hall, Nikki; Levina, Vita; Vine, John; Steel, Rohan

2014-10-01

The growth hormone releasing peptides (GHRPs) hexarelin, ipamorelin, alexamorelin, GHRP-1, GHRP-2, GHRP-4, GHRP-5, and GHRP-6 are all synthetic met-enkephalin analogues that include unnatural D-amino acids. They were designed specifically for their ability to stimulate growth hormone release and may serve as performance enhancing drugs. To regulate the use of these peptides within the horse racing industry and by human athletes, a method is presented for the extraction, derivatization, and detection of GHRPs from equine and human urine. This method takes advantage of a highly specific solid-phase extraction combined with a novel derivatization method to improve the chromatography of basic peptides. The method was validated with respect to linearity, repeatability, intermediate precision, specificity, limits of detection, limits of confirmation, ion suppression, and stability. As proof of principle, all eight GHRPs or their metabolites could be detected in urine collected from rats after intravenous administration. Copyright © 2014 John Wiley & Sons, Ltd.

Determination of patulin in commercial apple juice by micellar electrokinetic chromatography.

PubMed

Murillo, M; González-Peñas, E; Amézqueta, S

2008-01-01

A novel and validated micellar electrokinetic capillary chromatography (MEKC) method using ultraviolet detection (UV) has been applied to the quantitative analysis of patulin (PAT) in commercial apple juice. Patulin was extracted from samples with an ethylacetate solution. The micellar electrokinetic capillary chromatography (MECK) parameters studied for method optimization were buffer composition, voltage, temperature, and a separation between PAT and 5-hydroxymethylfurfural (HMF) (main interference in apple juice PAT analysis) peaks until reaching baseline. The method passes a series of validation tests including selectivity, linearity, limit of detection and quantification (0.7 and 2.5 microgL(-1), respectively), precision (within and between-day variability) and recovery (80.2% RSD=4%), accuracy, and robustness. This method was successfully applied to the measurement of 20 apple juice samples obtained from different supermarkets. One hundred percent of the samples were contaminated with a level greater than the limit of detection, with mean and median values of 41.3 and 35.7 microgL(-1), respectively.

Determination of seven flavonoids in Ixeridium gracile (DC.) Shih by high-performance liquid chromatography.

PubMed

Chen, Juan; Ma, Xue-Mei; Shi, Yan-Ping

2009-01-01

A high-performance liquid chromatographic technique coupled with photodiode array detection was proposed for the simultaneous determination of 7 flavonoids, i.e., quercetin, kaempferol, 7-hydroxyflavanone, 7-methoxyflavanone, 2',4'-dihydroxychalcone, 2',4'-dihydroxydihydrochalcone, and 7,2'-dihydroxy-3', 4'-dimethoxyisoflavane, in extracts of the plant Ixeridium gracile. Optimum separation was obtained by using a reversed-phase C18 method. Because of the different UV characteristics of these components, 5 detection wavelengths were used for the quantitative analysis. All of the flavonoids showed good linearity (r > 0.9999). The limit of detection and limit of quantitation values for the analytes ranged from 0.06 to 0.46 microg/mL and from 0.18 to 1.48 microg/mL, respectively. The method was validated by evaluating repeatability, precision, stability, and accuracy. Five different extraction and purification procedures were investigated for preparation of the sample solution. The optimized method was applied to the determination of flavonoids in I. gracile and was found to be efficient.

Natural occurrence of alternariol and alternariol monomethyl ether in soya beans.

PubMed

Oviedo, M S; Barros, G G; Chulze, S N; Ramirez, M L

2012-08-01

The natural occurrence of alternariol (AOH) and alternariol monomethyl ether (AME) in soya beans harvested in Argentina was evaluated. Both toxins were simultaneously detected by using HPLC analysis coupled with a solid phase extraction column clean-up. Characteristics of this in-house method such as accuracy, precision and detection and quantification limits were defined by means of recovery test with spiked soya bean samples. Out of 50 soya bean samples, 60% showed contamination with the mycotoxins analyzed; among them, 16% were only contaminated with AOH and 14% just with AME. Fifteen of the positive samples showed co-occurrence of both mycotoxins analyzed. AOH was detected in concentrations ranging from 25 to 211 ng/g, whereas AME was found in concentrations ranging from 62 to 1,153 ng/g. Although a limited number of samples were evaluated, this is the first report on the natural occurrence of Alternaria toxins in soya beans and is relevant from the point of view of animal public health.

Reversed phase HPLC for strontium ranelate: Method development and validation applying experimental design.

PubMed

Kovács, Béla; Kántor, Lajos Kristóf; Croitoru, Mircea Dumitru; Kelemen, Éva Katalin; Obreja, Mona; Nagy, Előd Ernő; Székely-Szentmiklósi, Blanka; Gyéresi, Árpád

2018-06-01

A reverse-phase HPLC (RP-HPLC) method was developed for strontium ranelate using a full factorial, screening experimental design. The analytical procedure was validated according to international guidelines for linearity, selectivity, sensitivity, accuracy and precision. A separate experimental design was used to demonstrate the robustness of the method. Strontium ranelate was eluted at 4.4 minutes and showed no interference with the excipients used in the formulation, at 321 nm. The method is linear in the range of 20-320 μg mL-1 (R2 = 0.99998). Recovery, tested in the range of 40-120 μg mL-1, was found to be 96.1-102.1 %. Intra-day and intermediate precision RSDs ranged from 1.0-1.4 and 1.2-1.4 %, resp. The limit of detection and limit of quantitation were 0.06 and 0.20 μg mL-1, resp. The proposed technique is fast, cost-effective, reliable and reproducible, and is proposed for the routine analysis of strontium ranelate.

Simultaneous quantification of withanolides in Withania somnifera by a validated high-performance thin-layer chromatographic method.

PubMed

Srivastava, Pooja; Tiwari, Neerja; Yadav, Akhilesh K; Kumar, Vijendra; Shanker, Karuna; Verma, Ram K; Gupta, Madan M; Gupta, Anil K; Khanuja, Suman P S

2008-01-01

This paper describes a sensitive, selective, specific, robust, and validated densitometric high-performance thin-layer chromatographic (HPTLC) method for the simultaneous determination of 3 key withanolides, namely, withaferin-A, 12-deoxywithastramonolide, and withanolide-A, in Ashwagandha (Withania somnifera) plant samples. The separation was performed on aluminum-backed silica gel 60F254 HPTLC plates using dichloromethane-methanol-acetone-diethyl ether (15 + 1 + 1 + 1, v/v/v/v) as the mobile phase. The withanolides were quantified by densitometry in the reflection/absorption mode at 230 nm. Precise and accurate quantification could be performed in the linear working concentration range of 66-330 ng/band with good correlation (r2 = 0.997, 0.999, and 0.996, respectively). The method was validated for recovery, precision, accuracy, robustness, limit of detection, limit of quantitation, and specificity according to International Conference on Harmonization guidelines. Specificity of quantification was confirmed using retention factor (Rf) values, UV-Vis spectral correlation, and electrospray ionization mass spectra of marker compounds in sample tracks.

Determination of the neuropharmacological drug nodakenin in rat plasma and brain tissues by liquid chromatography tandem mass spectrometry: Application to pharmacokinetic studies.

PubMed

Song, Yingshi; Yan, Huiyu; Xu, Jingbo; Ma, Hongxi

2017-09-01

A rapid and sensitive liquid chromatography tandem mass spectrometry detection using selected reaction monitoring in positive ionization mode was developed and validated for the quantification of nodakenin in rat plasma and brain. Pareruptorin A was used as internal standard. A single step liquid-liquid extraction was used for plasma and brain sample preparation. The method was validated with respect to selectivity, precision, accuracy, linearity, limit of quantification, recovery, matrix effect and stability. Lower limit of quantification of nodakenin was 2.0 ng/mL in plasma and brain tissue homogenates. Linear calibration curves were obtained over concentration ranges of 2.0-1000 ng/mL in plasma and brain tissue homogenates for nodakenin. Intra-day and inter-day precisions (relative standard deviation, RSD) were <15% in both biological media. This assay was successfully applied to plasma and brain pharmacokinetic studies of nodakenin in rats after intravenous administration. Copyright © 2017 John Wiley & Sons, Ltd.

Multinode acoustic focusing for parallel flow cytometry

PubMed Central

Piyasena, Menake E.; Suthanthiraraj, Pearlson P. Austin; Applegate, Robert W.; Goumas, Andrew M.; Woods, Travis A.; López, Gabriel P.; Graves, Steven W.

2012-01-01

Flow cytometry can simultaneously measure and analyze multiple properties of single cells or particles with high sensitivity and precision. Yet, conventional flow cytometers have fundamental limitations with regards to analyzing particles larger than about 70 microns, analyzing at flow rates greater than a few hundred microliters per minute, and providing analysis rates greater than 50,000 per second. To overcome these limits, we have developed multi-node acoustic focusing flow cells that can position particles (as small as a red blood cell and as large as 107 microns in diameter) into as many as 37 parallel flow streams. We demonstrate the potential of such flow cells for the development of high throughput, parallel flow cytometers by precision focusing of flow cytometry alignment microspheres, red blood cells, and the analysis of CD4+ cellular immunophenotyping assay. This approach will have significant impact towards the creation of high throughput flow cytometers for rare cell detection applications (e.g. circulating tumor cells), applications requiring large particle analysis, and high volume flow cytometry. PMID:22239072

Static headspace gas chromatographic method for quantitative determination of residual solvents in pharmaceutical drug substances according to european pharmacopoeia requirements.

PubMed

Otero, Raquel; Carrera, Guillem; Dulsat, Joan Francesc; Fábregas, José Luís; Claramunt, Juan

2004-11-19

A static headspace (HS) gas chromatographic method for quantitative determination of residual solvents in a drug substance has been developed according to European Pharmacopoeia general procedure. A water-dimethylformamide mixture is proposed as sample solvent to obtain good sensitivity and recovery. The standard addition technique with internal standard quantitation was used for ethanol, tetrahydrofuran and toluene determination. Validation was performed within the requirements of ICH validation guidelines Q2A and Q2B. Selectivity was tested for 36 solvents, and system suitability requirements described in the European Pharmacopoeia were checked. Limits of detection and quantitation, precision, linearity, accuracy, intermediate precision and robustness were determined, and excellent results were obtained.

Optical Links and RF Distribution for Antenna Arrays

NASA Technical Reports Server (NTRS)

Huang, Shouhua; Calhoun, Malcolm; Tjoelker, Robert

2006-01-01

An array of three antennas has recently been developed at the NASA Jet Propulsion Laboratory capable of detecting signals at X and Ka band. The array requires a common frequency reference and high precision phase alignment to correlate received signals. Frequency and timing references are presently provided from a remotely located hydrogen maser and clock through a combination of commercially and custom developed optical links. The selected laser, photodetector, and fiber components have been tested under anticipated thermal and simulated antenna rotation conditions. The resulting stability limitations due to thermal perturbations or induced stress on the optical fiber have been characterized. Distribution of the X band local oscillator includes a loop back and precision phase monitor to enable correlation of signals received from each antenna.

Multidetection of antibiotics in liver tissue by ultra-high-pressure-liquid-chromatography-tandem mass spectrometry.

PubMed

Freitas, Andreia; Barbosa, Jorge; Ramos, Fernando

2015-01-22

A multiresidue quantitative screening method covering 39 antibiotics from 7 different families by ultra-high-pressure-liquid-chromatography-tandem mass spectrometry (UHPLC-MS/MS) is described. Sulfonamides, trimethoprim, tetracyclines, macrolides, quinolones, penicillins and chloramphenicol are simultaneously detected in liver tissue. A simple sample treatment method consisting of extraction with a mixture of acetonitrile and ethylenediaminetetraacetic acid (EDTA) followed by solid-phase extraction (SPE) with a hydrophilic-lipophilic balanced (HLB) cartridge was developed. The methodology was validated, in accordance with Decision 2002/657/EC, by evaluating the following required parameters: decision limit (CCα), detection capability (CCβ), specificity, repeatability and reproducibility. The precision, in terms of the relative standard deviation, was under 22% for all of the compounds, and the recoveries were between 80% and 110%. The CCα and CCβ were determined according to the maximum residue limit (MRL) or the minimum required performance limit (MRPL), when established. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of alkyl phosphates in petroleum samples by comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection and post-column Deans switching.

PubMed

Nizio, Katie D; Harynuk, James J

2012-08-24

Alkyl phosphate based gellants used as viscosity builders for fracturing fluids used in the process of hydraulic fracturing have been implicated in numerous refinery-fouling incidents in North America. In response, industry developed an inductively coupled plasma optical emission spectroscopy (ICP-OES) based method for the analysis of total volatile phosphorus in distillate fractions of crude oil; however, this method is plagued by poor precision and a high limit of detection (0.5±1μg phosphorus mL(-1)). Furthermore this method cannot provide speciation information, which is critical for developing an understanding of the challenge of alkyl phosphates at a molecular level. An approach using comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection (GC×GC-NPD) and post-column Deans switching is presented. This method provides qualitative and quantitative profiles of alkyl phosphates in industrial petroleum samples with increased precision and at levels comparable to or below those achievable by ICP-OES. A recovery study in a fracturing fluid sample and a profiling study of alkyl phosphates in four recovered fracturing fluid/crude oil mixtures (flowback) are also presented. Copyright © 2012 Elsevier B.V. All rights reserved.

A diagnostic biochip for the comprehensive analysis of MLL translocations in acute leukemia.

PubMed

Maroc, N; Morel, A; Beillard, E; De La Chapelle, A L; Fund, X; Mozziconacci, M-J; Dupont, M; Cayuela, J-M; Gabert, J; Koki, A; Fert, V; Hermitte, F

2004-09-01

Reciprocal rearrangements of the MLL gene are among the most common chromosomal abnormalities in both Acute Lymphoblastic and Myeloid Leukemia. The MLL gene, located on the 11q23 chromosomal band, is involved in more than 40 recurrent translocations. In the present study, we describe the development and validation of a biochip-based assay designed to provide a comprehensive molecular analysis of MLL rearrangements when used in a standard clinical pathology laboratory. A retrospective blind study was run with cell lines (n=5), and MLL positive and negative patient samples (n=31), to evaluate assay performance. The limits of detection determined on cell line data were 10(-1), and the precision studies yielded 100% repeatability and 98% reproducibility. The study shows that the device can detect frequent (AF4, AF6, AF10, ELL or ENL) as well as rare partner genes (AF17, MSF). The identified fusion transcripts can then be used as molecular phenotypic markers of disease for the precise evaluation of minimal residual disease by RQ-PCR. This biochip-based molecular diagnostic tool allows, in a single experiment, rapid and accurate identification of MLL gene rearrangements among 32 different fusion gene (FG) partners, precise breakpoint positioning and comprehensive screening of all currently characterized MLL FGs.

QuEChERS-based purification method coupled to ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine six quaternary ammonium compounds (QACs) in dairy products.

PubMed

Xian, Yanping; Dong, Hao; Wu, Yuluan; Guo, Xindong; Hou, Xiangchang; Wang, Bin

2016-12-01

QuEChERS-based purification coupled with UPLC-MS/MS method, was developed for six quaternary ammonium compounds (QACs) determination in dairy products. Powder samples were firstly dispersed by water. Protein in liquid milk was precipitated and sample solution was extracted by acetonitrile. QuEChERS-based purification was used to purify the solution. QACs were finally separated by HILIC column and detected in MRM mode of MS/MS under ESI(+). The stable isotope benzyl-2,3,4,5,6-d5-dimethyltetradecylammonium bromide (C14-BAC-d5) was used as an internal standard. This method was validated in terms of linearity, sensitivity, precision, accuracy. Linear relations were favorable for QACs over the selected concentration ranges of 0.2-50μg/L, with correlation coefficients greater than 0.999. The limits of detection (LODs) were in the range of 0.4-14.5μg/kg. Recoveries were between 91.2% and 115% with RSDs of 2.8-7.5% for intra-day precision and 3.7-6.7% for inter-day precision. This validated method was successfully applied to determine the QACs concentrations in dairy products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Unambiguous quantum-state filtering

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

Takeoka, Masahiro; Sasaki, Masahide; CREST, Japan Science and Technology Corporation, Tokyo,

2003-07-01

In this paper, we consider a generalized measurement where one particular quantum signal is unambiguously extracted from a set of noncommutative quantum signals and the other signals are filtered out. Simple expressions for the maximum detection probability and its positive operator valued measure are derived. We apply such unambiguous quantum state filtering to evaluation of the sensing of decoherence channels. The bounds of the precision limit for a given quantum state of probes and possible device implementations are discussed.

Flow injection method for sulphide determination using an organic mercury compound

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

Yaqoob, M.; Anwar, M.; Masood, A.S.

1991-04-01

A simple flow injection analysis method is described for the determination of soluble sulfide, based on the complexation of sulfide with p-hydroxymercurbenzoic acid, in the presence of dithizone used as an indicator. The reaction is very rapid, with a sampling rate of 90/hr. and requires a very short length post injection reaction coil. The detection limit and precision are 0.01 mM and 0.7%, respectively.

Statistical analysis of water-quality data containing multiple detection limits II: S-language software for nonparametric distribution modeling and hypothesis testing

USGS Publications Warehouse

Lee, L.; Helsel, D.

2007-01-01

Analysis of low concentrations of trace contaminants in environmental media often results in left-censored data that are below some limit of analytical precision. Interpretation of values becomes complicated when there are multiple detection limits in the data-perhaps as a result of changing analytical precision over time. Parametric and semi-parametric methods, such as maximum likelihood estimation and robust regression on order statistics, can be employed to model distributions of multiply censored data and provide estimates of summary statistics. However, these methods are based on assumptions about the underlying distribution of data. Nonparametric methods provide an alternative that does not require such assumptions. A standard nonparametric method for estimating summary statistics of multiply-censored data is the Kaplan-Meier (K-M) method. This method has seen widespread usage in the medical sciences within a general framework termed "survival analysis" where it is employed with right-censored time-to-failure data. However, K-M methods are equally valid for the left-censored data common in the geosciences. Our S-language software provides an analytical framework based on K-M methods that is tailored to the needs of the earth and environmental sciences community. This includes routines for the generation of empirical cumulative distribution functions, prediction or exceedance probabilities, and related confidence limits computation. Additionally, our software contains K-M-based routines for nonparametric hypothesis testing among an unlimited number of grouping variables. A primary characteristic of K-M methods is that they do not perform extrapolation and interpolation. Thus, these routines cannot be used to model statistics beyond the observed data range or when linear interpolation is desired. For such applications, the aforementioned parametric and semi-parametric methods must be used.

Spectrofluorimetric determination of tobramycin in human serum and pharmaceutical preparations by derivatization with fluorescamine.

PubMed

Tekkeli, Serife Evrim Kepekci; Önal, Armağan; Sağırlı, A Olcay

2014-02-01

A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of tobramycin (TOB) in human serum and pharmaceutical preparations. The method is based on the reaction between the primary amino group of TOB and fluorescamine in borate buffer, pH 8.5, to give a highly fluorescent derivative which is measured at 469 nm after excitation at 388 nm. The fluorescence intensity was directly proportional to the concentration over the range 300-1500 ng/mL, with a limit of detection of 65 ng/mL and limit of quantitation of 215 ng/mL. All variables were investigated to optimize the reaction conditions. The method was validated according to International Conference on Harmonization guidelines in terms of specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. Good recoveries were obtained ranging from 97.4 to 100.64%, indicating that no interference was observed from concomitants usually present in pharmaceutical dosage forms. The method was successfully, applied for the analysis of the drug substance in its pharmaceutical preparations and spiked serum samples. Copyright © 2013 John Wiley & Sons, Ltd.

NearSense - Advances Towards a Silicon-Based Terahertz Near-Field Imaging Sensor for Ex Vivo Breast Tumour Identification

NASA Astrophysics Data System (ADS)

Mavarani, Laven; Hillger, Philipp; Bücher, Thomas; Grzyb, Janusz; Pfeiffer, Ullrich R.; Cassar, Quentin; Al-Ibadi, Amel; Zimmer, Thomas; Guillet, Jean-Paul; Mounaix, Patrick; MacGrogan, Gaëtan

2018-03-01

Breast Cancer is one of the most frequently diagnosed cancer diseases worldwide, and the most common invasive tumour for women. As with all cancers, early detection plays a major role in reducing the mortality and morbidity rate. Currently, most breast cancers are detected due to clinical symptoms, or by screening mammography. The limitations of these techniques have resulted in research of alternative methods for imaging and detecting breast cancer. Apart from this, it is essential to define precise tumour margins during breast-conserving surgeries to reduce the re-excision rate. This study presents the advances in the development of a silicon-based THz sub-wavelength imager usable in life science applications, especially for tumour margin identification.

Overcoming the detection bandwidth limit in precision spectroscopy: The analytical apparatus function for a stepped frequency scan

NASA Astrophysics Data System (ADS)

Rohart, François

2017-01-01

In a previous paper [Rohart et al., Phys Rev A 2014;90(042506)], the influence of detection-bandwidth properties on observed line-shapes in precision spectroscopy was theoretically modeled for the first time using the basic model of a continuous sweeping of the laser frequency. Specific experiments confirmed general theoretical trends but also revealed several insufficiencies of the model in case of stepped frequency scans. As a consequence in as much as up-to-date experiments use step-by-step frequency-swept lasers, a new model of the influence of the detection-bandwidth is developed, including a realistic timing of signal sampling and frequency changes. Using Fourier transform techniques, the resulting time domain apparatus function gets a simple analytical form that can be easily implemented in line-shape fitting codes without any significant increase of computation durations. This new model is then considered in details for detection systems characterized by 1st and 2nd order bandwidths, underlining the importance of the ratio of detection time constant to frequency step duration, namely for the measurement of line frequencies. It also allows a straightforward analysis of corresponding systematic deviations on retrieved line frequencies and broadenings. Finally, a special attention is paid to consequences of a finite detection-bandwidth in Doppler Broadening Thermometry, namely to experimental adjustments required for a spectroscopic determination of the Boltzmann constant at the 1-ppm level of accuracy. In this respect, the interest of implementing a Butterworth 2nd order filter is emphasized.

An event-specific method for the detection and quantification of ML01, a genetically modified Saccharomyces cerevisiae wine strain, using quantitative PCR.

PubMed

Vaudano, Enrico; Costantini, Antonella; Garcia-Moruno, Emilia

2016-10-03

The availability of genetically modified (GM) yeasts for winemaking and, in particular, transgenic strains based on the integration of genetic constructs deriving from other organisms into the genome of Saccharomyces cerevisiae, has been a reality for several years. Despite this, their use is only authorized in a few countries and limited to two strains: ML01, able to convert malic acid into lactic acid during alcoholic fermentation, and ECMo01 suitable for reducing the risk of carbamate production. In this work we propose a quali-quantitative culture-independent method for the detection of GM yeast ML01 in commercial preparations of ADY (Active Dry Yeast) consisting of efficient extraction of DNA and qPCR (quantitative PCR) analysis based on event-specific assay targeting MLC (malolactic cassette), and a taxon-specific S. cerevisiae assay detecting the MRP2 gene. The ADY DNA extraction methodology has been shown to provide good purity DNA suitable for subsequent qPCR. The MLC and MRP2 qPCR assay showed characteristics of specificity, dynamic range, limit of quantification (LOQ) limit of detection (LOD), precision and trueness, which were fully compliant with international reference guidelines. The method has been shown to reliably detect 0.005% (mass/mass) of GM ML01 S. cerevisiae in commercial preparations of ADY. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous Proteomic Discovery and Targeted Monitoring using Liquid Chromatography, Ion Mobility Spectrometry, and Mass Spectrometry.

PubMed

Burnum-Johnson, Kristin E; Nie, Song; Casey, Cameron P; Monroe, Matthew E; Orton, Daniel J; Ibrahim, Yehia M; Gritsenko, Marina A; Clauss, Therese R W; Shukla, Anil K; Moore, Ronald J; Purvine, Samuel O; Shi, Tujin; Qian, Weijun; Liu, Tao; Baker, Erin S; Smith, Richard D

2016-12-01

Current proteomic approaches include both broad discovery measurements and quantitative targeted analyses. In many cases, discovery measurements are initially used to identify potentially important proteins (e.g. candidate biomarkers) and then targeted studies are employed to quantify a limited number of selected proteins. Both approaches, however, suffer from limitations. Discovery measurements aim to sample the whole proteome but have lower sensitivity, accuracy, and quantitation precision than targeted approaches, whereas targeted measurements are significantly more sensitive but only sample a limited portion of the proteome. Herein, we describe a new approach that performs both discovery and targeted monitoring (DTM) in a single analysis by combining liquid chromatography, ion mobility spectrometry and mass spectrometry (LC-IMS-MS). In DTM, heavy labeled target peptides are spiked into tryptic digests and both the labeled and unlabeled peptides are detected using LC-IMS-MS instrumentation. Compared with the broad LC-MS discovery measurements, DTM yields greater peptide/protein coverage and detects lower abundance species. DTM also achieved detection limits similar to selected reaction monitoring (SRM) indicating its potential for combined high quality discovery and targeted analyses, which is a significant step toward the convergence of discovery and targeted approaches. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Simultaneous determination of related substances of telmisartan and hydrochlorothiazide in tablet dosage form by using reversed phase high performance liquid chromatographic method

PubMed Central

Mukhopadhyay, Sutirtho; Kadam, Kiran; Sawant, Laxman; Nachane, Dhanashree; Pandita, Nancy

2011-01-01

Objective: Telmisartan is a potent, long-lasting, nonpeptide antagonist of the angiotensin II type-1 (AT1) receptor that is indicated for the treatment of essential hypertension. Hydrochlorothiazide is a widely prescribed diuretic and it is indicated for the treatment of edema, control of essential hypertension and management of diabetes insipidus. In the current article a new, accurate, sensitive, precise, rapid, reversed phase high performance liquid chromatography (RP-HPLC) method was developed for determination of related substances of Telmisartan and Hydrochlorthiazide in tablet dosage form. Materials and Methods: Simultaneous determination of related substances was performed on Kromasil C18 analytical column (250 × 4.6 mm; 5μm pertical size) column at 40°C employing a gradient elution. Mobile phase consisting of solvent A (solution containing 2.0 g of potassium dihydrogen phosphate anhydrous and 1.04 g of Sodium 1- Hexane sulphonic acid monohydrate per liter of water, adjusted to pH 3.0 with orthophosphoric acid) and solvent B (mixture of Acetonitrile: Methanol in the ratio 80:20 v/v) was used at a flow rate of 1.0 ml min–1. UV detection was performed at 270 nm. Results: During method validation parameter such as precision, linearity, accuracy, specificity, limit of detection and quantification were evaluated, which remained within acceptable limits. Conclusions: HPLC analytical method is linear, accurate, precise, robust and specific, being able to separate the main drug from its degradation products. It may find application for the routine analysis of the related substances of both Telmisartan and Hydrochlorthiazide in this combination tablets. PMID:21966158

How good a clock is rotation? The stellar rotation-mass-age relationship for old field stars

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

Epstein, Courtney R.; Pinsonneault, Marc H., E-mail: epstein@astronomy.ohio-state.edu, E-mail: pinsono@astronomy.ohio-state.edu

2014-01-10

The rotation-mass-age relationship offers a promising avenue for measuring the ages of field stars, assuming the attendant uncertainties to this technique can be well characterized. We model stellar angular momentum evolution starting with a rotation distribution from open cluster M37. Our predicted rotation-mass-age relationship shows significant zero-point offsets compared to an alternative angular momentum loss law and published gyrochronology relations. Systematic errors at the 30% level are permitted by current data, highlighting the need for empirical guidance. We identify two fundamental sources of uncertainty that limit the precision of rotation-based ages and quantify their impact. Stars are born with amore » range of rotation rates, which leads to an age range at fixed rotation period. We find that the inherent ambiguity from the initial conditions is important for all young stars, and remains large for old stars below 0.6 M {sub ☉}. Latitudinal surface differential rotation also introduces a minimum uncertainty into rotation period measurements and, by extension, rotation-based ages. Both models and the data from binary star systems 61 Cyg and α Cen demonstrate that latitudinal differential rotation is the limiting factor for rotation-based age precision among old field stars, inducing uncertainties at the ∼2 Gyr level. We also examine the relationship between variability amplitude, rotation period, and age. Existing ground-based surveys can detect field populations with ages as old as 1-2 Gyr, while space missions can detect stars as old as the Galactic disk. In comparison with other techniques for measuring the ages of lower main sequence stars, including geometric parallax and asteroseismology, rotation-based ages have the potential to be the most precise chronometer for 0.6-1.0 M {sub ☉} stars.« less

Laser absorption spectroscopy applied to monitoring of short-lived climate pollutants (SLCPs)

NASA Astrophysics Data System (ADS)

Wang, Gaoxuan; Shen, Fengjiao; Yi, Hongming; Hubert, Patrice; Deguine, Alexandre; Petitprez, Denis; Maamary, Rabih; Augustin, Patrick; Fourmentin, Marc; Fertein, Eric; Sigrist, Markus W.; Ba, Tong-Nguyen; Chen, Weidong

2018-06-01

Enhanced mitigation of short-lived climate pollutants (SLCPs) has been recently paid more attention in order to provide more sizeable short-term reductions of global warming effects over the next several decades. We overview in this article our recent progress in the development of spectroscopic instruments for optical monitoring of major SLCPs based on laser absorption spectroscopy. Methane (CH4) and black carbon (BC) are the most important SLCPs contributing to the human enhancement of the global greenhouse effect after CO2. We present optical sensing of these two climate-change related atmospheric species to illustrate how "classical" spectroscopy can help to address today's challenging issues: (1) Photoacoustic measurements of BC optical absorption coefficient in order to determine its radiative-forcing related optical parameters (such as mass absorption coefficient, absorption Ångström coefficient) with higher precision (∼7.4% compared to 12-30% for filter-based methods routinely used nowadays). The 1σ (SNR = 1) minimum measurable volumetric mass density of 21 ng/m3 (in 60 s) for black carbon. (2) Direct absorption spectroscopy-based monitoring of methane (CH4) in field campaign to identify pollution source in conjunction with air mass back-trajectory modeling. Using a White-type multipass cell (an effective path-length of 175 m), a 1σ detection limit of 33.3 ppb in 218 s was achieved with a relative measurement precision of 1.1% and an overall measurement uncertainty of about 5.1%. Performance of the custom, lab-based instruments (in terms of detection limits, measurement precision, temporal response, etc.), spectroscopic measurement aspects, experimental details, spectral data processing, analysis and modeling of the observed environmental episode will be presented and discussed.

Research progress of on-the-go soil parameter sensors based on NIRS

NASA Astrophysics Data System (ADS)

An, Xiaofei; Meng, Zhijun; Wu, Guangwei; Guo, Jianhua

2014-11-01

Both the ever-increasing prices of fertilizer and growing ecological concern over chemical run-off into sources of drinking water have brought the issues of precision agriculture and site-specific management to the forefront of present technological development within agriculture and ecology. Soil is an important and basic element in agriculture production. Acquisition of soil information plays an important role in precision agriculture. The soil parameters include soil total nitrogen, phosporus, potassium, soil organic matter, soil moisture, electrical conductivity and pH value and so on. Field rapid acquisition to all the kinds of soil physical and chemical parameters is one of the most important research directions. And soil parameter real-time monitoring is also the trend of future development in precision agriculture. While developments in precision agriculture and site-specific management procedures have made significant in-roads on these issues and many researchers have developed effective means to determine soil properties, routinely obtaining robust on-the-go measurements of soil properties which are reliable enough to drive effective fertilizer application remains a challenge. NIRS technology provides a new method to obtain soil parameter with low cost and rapid advantage. In this paper, research progresses of soil on-the-go spectral sensors at domestic and abroad was combed and analyzed. There is a need for the sensing system to perform at least six key indexes for any on-the-go soil spectral sensor to be successful. The six indexes are detection limit, specificity, robustness, accuracy, cost and easy-to-use. Both the research status and problems were discussed. Finally, combining the national conditions of china, development tendency of on-the-go soil spectral sensors was proposed. In the future, on-the-go soil spectral sensors with reliable enough, sensitive enough and continuous detection would become popular in precision agriculture.

Precise Quantitation of MicroRNA in a Single Cell with Droplet Digital PCR Based on Ligation Reaction.

PubMed

Tian, Hui; Sun, Yuanyuan; Liu, Chenghui; Duan, Xinrui; Tang, Wei; Li, Zhengping

2016-12-06

MicroRNA (miRNA) analysis in a single cell is extremely important because it allows deep understanding of the exact correlation between the miRNAs and cell functions. Herein, we wish to report a highly sensitive and precisely quantitative assay for miRNA detection based on ligation-based droplet digital polymerase chain reaction (ddPCR), which permits the quantitation of miRNA in a single cell. In this ligation-based ddPCR assay, two target-specific oligonucleotide probes can be simply designed to be complementary to the half-sequence of the target miRNA, respectively, which avoids the sophisticated design of reverse transcription and provides high specificity to discriminate a single-base difference among miRNAs with simple operations. After the miRNA-templated ligation, the ddPCR partitions individual ligated products into a water-in-oil droplet and digitally counts the fluorescence-positive and negative droplets after PCR amplification for quantification of the target molecules, which possesses the power of precise quantitation and robustness to variation in PCR efficiency. By integrating the advantages of the precise quantification of ddPCR and the simplicity of the ligation-based PCR, the proposed method can sensitively measure let-7a miRNA with a detection limit of 20 aM (12 copies per microliter), and even a single-base difference can be discriminated in let-7 family members. More importantly, due to its high selectivity and sensitivity, the proposed method can achieve precise quantitation of miRNAs in single-cell lysate. Therefore, the ligation-based ddPCR assay may serve as a useful tool to exactly reveal the miRNAs' actions in a single cell, which is of great importance for the study of miRNAs' biofunction as well as for the related biomedical studies.

Feasibility of precise navigation in high and low latitude regions under scintillation conditions

NASA Astrophysics Data System (ADS)

Juan, José Miguel; Sanz, Jaume; González-Casado, Guillermo; Rovira-Garcia, Adrià; Camps, Adriano; Riba, Jaume; Barbosa, José; Blanch, Estefania; Altadill, David; Orus, Raul

2018-02-01

Scintillation is one of the most challenging problems in Global Navigation Satellite Systems (GNSS) navigation. This phenomenon appears when the radio signal passes through ionospheric irregularities. These irregularities represent rapid changes on the refraction index and, depending on their size, they can produce also diffractive effects affecting the signal amplitude and, eventually producing cycle slips. In this work, we show that the scintillation effects on the GNSS signal are quite different in low and high latitudes. For low latitude receivers, the main effects, from the point of view of precise navigation, are the increase of the carrier phase noise (measured by σϕ) and the fade on the signal intensity (measured by S4) that can produce cycle slips in the GNSS signal. With several examples, we show that the detection of these cycle slips is the most challenging problem for precise navigation, in such a way that, if these cycle slips are detected, precise navigation can be achieved in these regions under scintillation conditions. For high-latitude receivers the situation differs. In this region the size of the irregularities is typically larger than the Fresnel length, so the main effects are related with the fast change on the refractive index associated to the fast movement of the irregularities (which can reach velocities up to several km/s). Consequently, the main effect on the GNSS signals is a fast fluctuation of the carrier phase (large σϕ), but with a moderate fade in the amplitude (moderate S4). Therefore, as shown through several examples, fluctuations at high-latitude usually do not produce cycle slips, being the effect quite limited on the ionosphere-free combination and, in general, precise navigation can be achieved also during strong scintillation conditions.

Modeling of direct detection Doppler wind lidar. I. The edge technique.

PubMed

McKay, J A

1998-09-20

Analytic models, based on a convolution of a Fabry-Perot etalon transfer function with a Gaussian spectral source, are developed for the shot-noise-limited measurement precision of Doppler wind lidars based on the edge filter technique by use of either molecular or aerosol atmospheric backscatter. The Rayleigh backscatter formulation yields a map of theoretical sensitivity versus etalon parameters, permitting design optimization and showing that the optimal system will have a Doppler measurement uncertainty no better than approximately 2.4 times that of a perfect, lossless receiver. An extension of the models to include the effect of limited etalon aperture leads to a condition for the minimum aperture required to match light collection optics. It is shown that, depending on the choice of operating point, the etalon aperture finesse must be 4-15 to avoid degradation of measurement precision. A convenient, closed-form expression for the measurement precision is obtained for spectrally narrow backscatter and is shown to be useful for backscatter that is spectrally broad as well. The models are extended to include extrinsic noise, such as solar background or the Rayleigh background on an aerosol Doppler lidar. A comparison of the model predictions with experiment has not yet been possible, but a comparison with detailed instrument modeling by McGill and Spinhirne shows satisfactory agreement. The models derived here will be more conveniently implemented than McGill and Spinhirne's and more readily permit physical insights to the optimization and limitations of the double-edge technique.

High-precision processing and detection of the high-caliber off-axis aspheric mirror

NASA Astrophysics Data System (ADS)

Dai, Chen; Li, Ang; Xu, Lingdi; Zhang, Yingjie

2017-10-01

To achieve the efficient, controllable, digital processing and high-precision detection of the high-caliber off-axis aspheric mirror, meeting the high-level development needs of the modern high-resolution, large field of space optical remote sensing camera, we carried out the research on high precision machining and testing technology of off-axis aspheric mirror. First, we forming the off-axis aspheric sample with diameter of 574mm × 302mm by milling it with milling machine, and then the intelligent robot equipment was used for off-axis aspheric high precision polishing. Surface detection of the sample will be proceed with the off-axis aspheric contact contour detection technology and offaxis non-spherical surface interference detection technology after its fine polishing using ion beam equipment. The final surface accuracy RMS is 12nm.

A continuous-flow denuder for the measurement of ambient concentrations and surface-exchange fluxes of ammonia

NASA Astrophysics Data System (ADS)

Wyers, G. P.; Otjes, R. P.; Slanina, J.

A new diffusion denuder is described for the continuous measurement of atmospheric ammonia. Ammonia is collected in an absorption solution in a rotating denuder, separated from interfering compounds by diffusion through a semi-permeable membrane and detected by conductometry. The method is free from interferences by other atmospheric gases, with the exception of volatile amines. The detection limit is 6 ng m -3 for a 30-min integration time. This compact instrument is fully automated and suited for routine deployment in field studies. The precision is sufficiently high for micrometeorological studies of air-surface exchange of ammonia.

Microlensing Constraints on the Mass of Single Stars from HST Astrometric Measurements

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

Kains, N.; Calamida, A.; Sahu, K. C.

Here, we report on the first results from a large-scale observing campaign aiming to use astrometric microlensing to detect and place limits on the mass of single objects, including stellar remnants. We used the Hubble Space Telescope to monitor stars near the Galactic Center for three years, and we measured the brightness and positions of ~2 million stars at each observing epoch. In addition to this, we monitored the same pointings using the VIMOS imager on the Very Large Telescope. The stars we monitored include several bright microlensing events observed from the ground by the OGLE collaboration. In this paper,more » we present the analysis of our photometric and astrometric measurements for six of these events, and derive mass constraints for the lens in each of them. Although these constraints are limited by the photometric precision of ground-based data, and our ability to determine the lens distance, we were able to constrain the size of the Einstein ring radius thanks to our precise astrometric measurements—the first routine measurements of this type from a large-scale observing program. In conclusion, this demonstrates the power of astrometric microlensing as a tool to constrain the masses of stars, stellar remnants, and, in the future, extrasolar planets, using precise ground- and space-based observations.« less

Microlensing Constraints on the Mass of Single Stars from HST Astrometric Measurements

DOE PAGES

Kains, N.; Calamida, A.; Sahu, K. C.; ...

2017-07-14

Here, we report on the first results from a large-scale observing campaign aiming to use astrometric microlensing to detect and place limits on the mass of single objects, including stellar remnants. We used the Hubble Space Telescope to monitor stars near the Galactic Center for three years, and we measured the brightness and positions of ~2 million stars at each observing epoch. In addition to this, we monitored the same pointings using the VIMOS imager on the Very Large Telescope. The stars we monitored include several bright microlensing events observed from the ground by the OGLE collaboration. In this paper,more » we present the analysis of our photometric and astrometric measurements for six of these events, and derive mass constraints for the lens in each of them. Although these constraints are limited by the photometric precision of ground-based data, and our ability to determine the lens distance, we were able to constrain the size of the Einstein ring radius thanks to our precise astrometric measurements—the first routine measurements of this type from a large-scale observing program. In conclusion, this demonstrates the power of astrometric microlensing as a tool to constrain the masses of stars, stellar remnants, and, in the future, extrasolar planets, using precise ground- and space-based observations.« less

Simultaneous Determination of Crypto-Chlorogenic Acid, Isoquercetin, and Astragalin Contents in Moringa oleifera Leaf Extracts by TLC-Densitometric Method.

PubMed

Vongsak, Boonyadist; Sithisarn, Pongtip; Gritsanapan, Wandee

2013-01-01

Moringa oleifera Lamarck (Moringaceae) is used as a multipurpose medicinal plant for the treatment of various diseases. Isoquercetin, astragalin, and crypto-chlorogenic acid have been previously found to be major active components in the leaves of this plant. In this study, a thin-layer-chromatography (TLC-)densitometric method was developed and validated for simultaneous quantification of these major components in the 70% ethanolic extracts of M. oleifera leaves collected from 12 locations. The average amounts of crypto-chlorogenic acid, isoquercetin, and astragalin were found to be 0.0473, 0.0427, and 0.0534% dry weight, respectively. The method was validated for linearity, precision, accuracy, limit of detection, limit of quantitation, and robustness. The linearity was obtained in the range of 100-500 ng/spot with a correlation coefficient (r) over 0.9961. Intraday and interday precisions demonstrated relative standard deviations of less than 5%. The accuracy of the method was confirmed by determining the recovery. The average recoveries of each component from the extracts were in the range of 98.28 to 99.65%. Additionally, the leaves from Chiang Mai province contained the highest amounts of all active components. The proposed TLC-densitometric method was simple, accurate, precise, and cost-effective for routine quality controlling of M. oleifera leaf extracts.

Development of a high-throughput method based on thin-film microextraction using a 96-well plate system with a cork coating for the extraction of emerging contaminants in river water samples.

PubMed

Morés, Lucas; Dias, Adriana Neves; Carasek, Eduardo

2018-02-01

In this study, a new method was developed in which a biosorbent material is used as the extractor phase in conjunction with a recently described sample preparation technique called thin-film microextraction and a 96-well plate system. The method was applied for the determination of emerging contaminants, such as 3-(4-methylbenzylidene) camphor, ethylparaben, triclocarban, and bisphenol A in water samples. The separation and detection of the analytes were performed by high-performance liquid chromatography with diode array detection. These contaminants are considered hazardous to human health and other living beings. Thus, the development of an analytical method to determine these compounds is of great interest. The extraction parameters were evaluated using multivariate and univariate optimization techniques. The optimum conditions for the method were 3 h of extraction time, 20 min of desorption with 300 μL of acetonitrile and methanol (50:50, v/v), and the addition of 5% w/v sodium chloride to the sample. The analytical figures of merit showed good results with linear correlation coefficients higher than 0.99, relative recoveries of 72-125%, interday precision (n = 3) of 4-18%, and intraday precision (n = 9) of 1-21%. The limit of detection was 0.3-5.5 μg/L, and the limit of quantification was 0.8-15 μg/L. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of an ion-pair HPLC method for investigation of energy charge changes in cerebral ischemia of mice and hypoxia of Neuro-2a cell line.

PubMed

Chen, Yunyun; Xing, Dongming; Wang, Wei; Ding, Yi; Du, Lijun

2007-06-01

The determination of adenine nucleotides and energy charge (EC) has great importance in the characterization of cerebral ischemic injury and post-ischemic recovery. An IP-HPLC method was developed for the quantification of AMP, ADP, ATP and EC in cerebral ischemia and hypoxia of the Neuro-2a cell line. The chromatographic conditions were: a Zorbax SB-C18 reversed-phase column; mobile phase 100 mM KH(2)PO(4), 1 mM tetrabutylammonium hydroxide, and 2.5% acetonitrile, brought to pH 7.0 with potassium hydroxide (4 M), filtered through a 0.45 microm Millipore filter and degassed prior to use. The flow-rate was 1.0 mL/min. The injection volume was 20 microL. Detection was performed at a wavelength of 254 nm under a constant temperature (27 +/- 1 degrees C). The method was validated by means of linearity, using calibration curves constructed with five concentration levels of each compound. The limit of detection was also determined. The system precision was calculated as the coefficient of variation for five injections for each compound tested. Cerebral tissue was homogenized (4 degrees C) in 1 mL of an ice-cold 6% trichloroacetic acid that contained ATPase inhibitor and obtained good recovery (>90%). The results show that the described method for the determination of adenine nucleotides by HPLC has good linearity, limit of detection, precision and specificity, and is simple and rapid to perform. Copyright 2007 John Wiley & Sons, Ltd.

Simultaneous determination of five major compounds in the traditional medicine Pyeongwee-San by high performance liquid chromatography-diode array detection and liquid chromatography-mass spectrometry/mass spectrometry.

PubMed

Lee, Bohyoung; Weon, Jin Bae; Yun, Bo-Ra; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Pyeongwee-San (PWS) has been widely used for treating acute gastritis, chronic, and gastritis. In this paper, simultaneous determination of five compounds (naringin, hesperidin, glycyrrhizin, atractylenolide III, and magnolol) from traditional medicine PWS using the high performance liquid chromatography (HPLC) was established for quality control. Optimum separations were obtained with a SHISEIDO C18 reverse-phase column by gradient elution with 0.1% Trifluoroacetic acid (TFA) water-acetonitrile as the mobile phase. The flow rate was 1 mL/min and detection wavelength was set at 205 nm and 250 nm. Validation of the analytical method was evaluated by linearity, precision, and accuracy test. The calibration curves were linear over the established range with R (2) > 0.9978. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.09 to 0.43 and 0.27 to 1.29 μg/mL. The method exhibited intra-day and inter-day precision range between 0.01-1.86% and 0.04-0.35% respectively. The recoveries of five compounds in PWS were in the range between 93.18-106.40%, and 0.20-1.51%. The application of this method was identified through the successful analysis of five compounds in 12 batches of PWS. In addition, identification of five compounds was confirmed by a liquid chromatography method and mass spectrometry. The HPLC method was could be accomplished to the quality control and stable experiment for the preparations consisted of five major compounds.

Comprehensive determination of flavouring additives and nicotine in e-cigarette refill solutions. Part I: Liquid chromatography-tandem mass spectrometry analysis.

PubMed

Aszyk, Justyna; Kubica, Paweł; Kot-Wasik, Agata; Namieśnik, Jacek; Wasik, Andrzej

2017-10-13

Liquid chromatography-tandem mass spectrometry with electrospray ionization (HPLC-ESI-MS/MS) methods were developed for the simultaneous determination of 42 flavouring compounds and nicotine in liquids for e-cigarettes. The chromatographic separation was performed using an Ace ® Ultracore™ SuperC18™ (100×2.1mm, 2.5μm) column in both acidic and alkaline pH conditions to separate all the compounds. A simple "dilute & shoot" approach was used for the sample preparation. The method validation was performed by evaluating key analytical parameters such as linearity, accuracy, selectivity, precision, limit of detection (LOD) and limit of quantification (LOQ). The calibration curves showed good linearity within the specific ranges for the investigated compounds with correlation coefficients greater than 0.990 in each case. The recovery for all the investigated compounds varied from 89% to 110%. The intra- and inter-day precision were within the acceptable limits (±15%) at all tested concentrations. The applicability of the methods was examined by analysing 25 liquid samples from e-cigarettes commercially available on the Polish market. Copyright © 2017 Elsevier B.V. All rights reserved.

Leaner and greener analysis of cannabinoids.

PubMed

Mudge, Elizabeth M; Murch, Susan J; Brown, Paula N

2017-05-01

There is an explosion in the number of labs analyzing cannabinoids in marijuana (Cannabis sativa L., Cannabaceae) but existing methods are inefficient, require expert analysts, and use large volumes of potentially environmentally damaging solvents. The objective of this work was to develop and validate an accurate method for analyzing cannabinoids in cannabis raw materials and finished products that is more efficient and uses fewer toxic solvents. An HPLC-DAD method was developed for eight cannabinoids in cannabis flowers and oils using a statistically guided optimization plan based on the principles of green chemistry. A single-laboratory validation determined the linearity, selectivity, accuracy, repeatability, intermediate precision, limit of detection, and limit of quantitation of the method. Amounts of individual cannabinoids above the limit of quantitation in the flowers ranged from 0.02 to 14.9% w/w, with repeatability ranging from 0.78 to 10.08% relative standard deviation. The intermediate precision determined using HorRat ratios ranged from 0.3 to 2.0. The LOQs for individual cannabinoids in flowers ranged from 0.02 to 0.17% w/w. This is a significant improvement over previous methods and is suitable for a wide range of applications including regulatory compliance, clinical studies, direct patient medical services, and commercial suppliers.

X-Ray Microanalysis and Electron Energy Loss Spectrometry in the Analytical Electron Microscope: Review and Future Directions

NASA Technical Reports Server (NTRS)

Goldstein, J. I.; Williams, D. B.

1992-01-01

This paper reviews and discusses future directions in analytical electron microscopy for microchemical analysis using X-ray and Electron Energy Loss Spectroscopy (EELS). The technique of X-ray microanalysis, using the ratio method and k(sub AB) factors, is outlined. The X-ray absorption correction is the major barrier to the objective of obtaining I% accuracy and precision in analysis. Spatial resolution and Minimum Detectability Limits (MDL) are considered with present limitations of spatial resolution in the 2 to 3 microns range and of MDL in the 0.1 to 0.2 wt. % range when a Field Emission Gun (FEG) system is used. Future directions of X-ray analysis include improvement in X-ray spatial resolution to the I to 2 microns range and MDL as low as 0.01 wt. %. With these improvements the detection of single atoms in the analysis volume will be possible. Other future improvements include the use of clean room techniques for thin specimen preparation, quantification available at the I% accuracy and precision level with light element analysis quantification available at better than the 10% accuracy and precision level, the incorporation of a compact wavelength dispersive spectrometer to improve X-ray spectral resolution, light element analysis and MDL, and instrument improvements including source stability, on-line probe current measurements, stage stability, and computerized stage control. The paper reviews the EELS technique, recognizing that it has been slow to develop and still remains firmly in research laboratories rather than in applications laboratories. Consideration of microanalysis with core-loss edges is given along with a discussion of the limitations such as specimen thickness. Spatial resolution and MDL are considered, recognizing that single atom detection is already possible. Plasmon loss analysis is discussed as well as fine structure analysis. New techniques for energy-loss imaging are also summarized. Future directions in the EELS technique will be the development of new spectrometers and improvements in thin specimen preparation. The microanalysis technique needs to be simplified and software developed so that the EELS technique approaches the relative simplicity of the X-ray technique. Finally, one can expect major improvements in EELS imaging as data storage and processing improvements occur.

Development of a novel low frequency GPR system for ultra-deep detection in Mine

NASA Astrophysics Data System (ADS)

Xu, Xianlei; Peng, Suping; Yang, Feng

2016-04-01

Mine disasters sources is the main source of the underground coal mine accidents in China. This paper describes the development of a novel explosion proof ground penetrating radar (GPR) for mine disasters sources detection, aiming to solve the current problems of the small detection range and low precision in the mine advanced detection in China. A high performance unipolar pulse transmitting unit is developed by using avalanche transistors, and an effective pulse excitation source network. And a new pluggable combined low-frequency antenna involving three frequencies with 12.5MHz, 25 MHz and 50MHz, is designed and developed. The plate-type structure is designed, aiming to enhance the directivity of the antenna, and the achievement of the antenna impedance matching is implemented in the feed point based on the extensions interface design, enhancing the antenna bandwidth and reducing the standing wave interference. Moreover, a high precision stepper delay circuit is designed by transforming the number of the operational amplifier step and using the differential compensation between the metal-oxide semiconductor field effect transistors, aiming to improve the accuracy of the signal acquisition system. In order to adapt to the mine environment, the explosion-proof design is implemented for the GPR system, including the host, transmitter, receiver, battery box, antenna, and other components.Mine detection experiments is carried out and the results show: the novel GPR system can effectively detect the location and depth of the geological disasters source with the depth greater than30 m and the diameter greater than 3m, the maximum detection depth can be up to 80m, which break the current detection depth limitations within 30m, providing an effective technical support for the ultra-deep mine disasters detection and the safety problems in coal mine production.

Detection of biological particles by the use of circular dichroism measurements improved by scattering theory

NASA Astrophysics Data System (ADS)

Rosen, David L.; Pendleton, J. David

1995-09-01

Light scattered from optically active spheres was theoretically analyzed for biodetection. The circularly polarized signal of near-forward scattering from circularly dichroic spheres was calculated. Both remote and point biodetection were considered. The analysis included the effect of a circular aperture and beam block at the detector. If the incident light is linearly polarized, a false signal would limit the sensitivity of the biodetector. If the incident light is randomly polarized, shot noise would limit the sensitivity. Suggested improvements to current techniques include a beam block, precise angular measurements, randomly polarized light, index-matching fluid, and larger apertures for large particles.

Reduction and possible elimination of coating thermal noise using a rigidly controlled cavity with a quantum-nondemolition technique.

PubMed

Somiya, Kentaro

2009-06-12

Thermal noise of a mirror is one of the most important issues in high-precision measurements such as gravitational-wave detection or cold damping experiments. It has been pointed out that thermal noise of a mirror with multilayer coatings can be reduced by mechanical separation of the layers. In this Letter, we introduce a way to further reduce thermal noise by locking the mechanically separated mirrors. The reduction is limited by the standard quantum limit of control noise, but it can be overcome with a quantum-nondemolition technique, which finally raises a possibility of complete elimination of coating thermal noise.

A real-time surface inspection system for precision steel balls based on machine vision

NASA Astrophysics Data System (ADS)

Chen, Yi-Ji; Tsai, Jhy-Cherng; Hsu, Ya-Chen

2016-07-01

Precision steel balls are one of the most fundament components for motion and power transmission parts and they are widely used in industrial machinery and the automotive industry. As precision balls are crucial for the quality of these products, there is an urgent need to develop a fast and robust system for inspecting defects of precision steel balls. In this paper, a real-time system for inspecting surface defects of precision steel balls is developed based on machine vision. The developed system integrates a dual-lighting system, an unfolding mechanism and inspection algorithms for real-time signal processing and defect detection. The developed system is tested under feeding speeds of 4 pcs s-1 with a detection rate of 99.94% and an error rate of 0.10%. The minimum detectable surface flaw area is 0.01 mm2, which meets the requirement for inspecting ISO grade 100 precision steel balls.

Validation of a QuEChERS-based gas chromatographic method for analysis of pesticide residues in Cassia angustifolia (senna).

PubMed

Tripathy, Vandana; Saha, Ajoy; Patel, Dilipkumar J; Basak, B B; Shah, Paresh G; Kumar, Jitendra

2016-08-02

A simple multi-residue method based on modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach was established for the determination of 17 organochlorine (OC), 15 organophosphorous (OP) and 7 synthetic pyrethroid (SP) pesticides in an economically important medicinal plant of India, Senna (Cassia angustifolia), by gas chromatography coupled to electron capture and flame thermionic detectors (GC/ECD/FTD) and confirmation of residues was done on gas chromatograph coupled with mass spectrometry (GC-MS). The developed method was validated by testing the following parameters: linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effect, accuracy-precision and measurement uncertainty; the validation study clearly demonstrated the suitability of the method for its intended application. All pesticides showed good linearity in the range 0.01-1.0 μg mL(-1) for OCs and OPs and 0.05-2.5 μg mL(-1) for SPs with correlation coefficients higher than 0.98. The method gave good recoveries for most of the pesticides (70-120%) with intra-day and inter-day precision < 20% in most of the cases. The limits of detection varied from 0.003 to 0.03 mg kg(-1), and the LOQs were determined as 0.01-0.049 mg kg(-1). The expanded uncertainties were <30%, which was distinctively less than a maximum default value of ±50%. The proposed method was successfully applied to determine pesticide residues in 12 commercial market samples obtained from different locations in India.

VaDiR: an integrated approach to Variant Detection in RNA.

PubMed

Neums, Lisa; Suenaga, Seiji; Beyerlein, Peter; Anders, Sara; Koestler, Devin; Mariani, Andrea; Chien, Jeremy

2018-02-01

Advances in next-generation DNA sequencing technologies are now enabling detailed characterization of sequence variations in cancer genomes. With whole-genome sequencing, variations in coding and non-coding sequences can be discovered. But the cost associated with it is currently limiting its general use in research. Whole-exome sequencing is used to characterize sequence variations in coding regions, but the cost associated with capture reagents and biases in capture rate limit its full use in research. Additional limitations include uncertainty in assigning the functional significance of the mutations when these mutations are observed in the non-coding region or in genes that are not expressed in cancer tissue. We investigated the feasibility of uncovering mutations from expressed genes using RNA sequencing datasets with a method called Variant Detection in RNA(VaDiR) that integrates 3 variant callers, namely: SNPiR, RVBoost, and MuTect2. The combination of all 3 methods, which we called Tier 1 variants, produced the highest precision with true positive mutations from RNA-seq that could be validated at the DNA level. We also found that the integration of Tier 1 variants with those called by MuTect2 and SNPiR produced the highest recall with acceptable precision. Finally, we observed a higher rate of mutation discovery in genes that are expressed at higher levels. Our method, VaDiR, provides a possibility of uncovering mutations from RNA sequencing datasets that could be useful in further functional analysis. In addition, our approach allows orthogonal validation of DNA-based mutation discovery by providing complementary sequence variation analysis from paired RNA/DNA sequencing datasets.

Development of an LC-MS/MS analytical method for the simultaneous measurement of aldehydes from polyunsaturated fatty acids degradation in animal feed.

PubMed

Douny, Caroline; Bayram, Pinar; Brose, François; Degand, Guy; Scippo, Marie-Louise

2016-05-01

Knowing that polyunsaturated fatty acids can lead to the formation of potentially toxic aldehydes as secondary oxidation products, an analytical method using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) detection was developed to measure the concentration of eight aldehydes in animal feed: malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), 4-hydroxy-2-hexenal (4-HHE), crotonaldehyde (CRT), benzaldehyde (BNZ), hexanal (HXL), 2,4-nonadienal, and 2,4-decadienal. The developed method was validated according to the criteria and procedure described in international standards. The evaluated parameters were specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, using the concept of accuracy profiles. These parameters were determined during experiments conducted over three different days with ground Kellogg's® Corn Flakes® cereals as model matrix for animal feed and spiked at different levels of concentration. Malondialdehyde, 4-HHE, 4-HNE, crotonaldehyde, benzaldehyde, and hexanal can be analyzed in the same run in animal feed with a very good accuracy, with recovery rates ranging from 86 to 109% for a working range going from 0.16 to 12.50 mg/kg. The analysis of 2,4-nonadienal and 2,4-decadienal can also be performed but in a limited range of concentration and with a limited degree of accuracy. Their recovery rates ranged between 54 and 114% and coefficient of variation for the intermediate precision between 11 and 25% for these two compounds. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Full-text automated detection of surgical site infections secondary to neurosurgery in Rennes, France.

PubMed

Campillo-Gimenez, Boris; Garcelon, Nicolas; Jarno, Pascal; Chapplain, Jean Marc; Cuggia, Marc

2013-01-01

The surveillance of Surgical Site Infections (SSI) contributes to the management of risk in French hospitals. Manual identification of infections is costly, time-consuming and limits the promotion of preventive procedures by the dedicated teams. The introduction of alternative methods using automated detection strategies is promising to improve this surveillance. The present study describes an automated detection strategy for SSI in neurosurgery, based on textual analysis of medical reports stored in a clinical data warehouse. The method consists firstly, of enrichment and concept extraction from full-text reports using NOMINDEX, and secondly, text similarity measurement using a vector space model. The text detection was compared to the conventional strategy based on self-declaration and to the automated detection using the diagnosis-related group database. The text-mining approach showed the best detection accuracy, with recall and precision equal to 92% and 40% respectively, and confirmed the interest of reusing full-text medical reports to perform automated detection of SSI.

[Analysis of Arsenic Compounds in Blood and Urine by HPLC-ICP-MS].

PubMed

Lin, L; Zhang, S J; Xu, W C; Luo, R X; Ma, D; Shen, M

2018-02-01

To establish an analysis method for the detection of 6 arsenic compounds [AsC, AsB, As（Ⅲ）, DMA, MMA and As（V）] in blood and urine by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry （HPLC-ICP-MS）, and apply it to real cases. Triton was used to damage cells, and then EDTA·2Na·2H2O was used to complex arsenic compounds in cells, and sonication and protein deposition by acetonitrile were performed for sample pretreatment. With the mobile phase consisted of ammonium carbonate and ultrapure water, gradient elution was performed for obtaining the arsenic compounds in samples, which were analysed by ICP-MS with Hamilton PRP-X100 column. The limits of detection in blood were 1.66-10 ng/mL, while the lower limits of quantitation in blood ranged from 5 to 30 ng/mL. The limits of detection in urine were 0.5-10 ng/mL, while the lower limits of quantitation in urine were 5-30 ng/mL. The relative standard deviation of inter-day and intra-day precisions was less than 10%. This method had been successfully applied to 3 cases. This study has established an analysis method for detecting 6 common arsenic compounds in blood and urine, which can be used to detect the arsenic compounds in the blood and urine from arsenic poisoning cases as well as the patients under arsenic treatment. Copyright© by the Editorial Department of Journal of Forensic Medicine.

The detection of planetary systems from Space Station - A star observation strategy

NASA Technical Reports Server (NTRS)

Mascy, Alfred C.; Nishioka, Ken; Jorgensen, Helen; Swenson, Byron L.

1987-01-01

A 10-20-yr star-observation program for the Space Station Astrometric Telescope Facility (ATF) is proposed and evaluated by means of computer simulations. The primary aim of the program is to detect stars with planetary systems by precise determination of their motion relative to reference stars. The designs proposed for the ATF are described and illustrated; the basic parameters of the 127 stars selected for the program are listed in a table; spacecraft and science constraints, telescope slewing rates, and the possibility of limiting the program sample to stars near the Galactic equator are discussed; and the effects of these constraints are investigated by simulating 1 yr of ATF operation. Viewing all sky regions, the ATF would have 81-percent active viewing time, observing each star about 200 times (56 h) per yr; only small decrements in this performance would result from limiting the viewing field.

Development and validation of a hydrophilic interaction chromatography-mass spectrometry assay for taurine and methionine in matrices rich in carbohydrates.

PubMed

de Person, Marine; Hazotte, Aurélie; Elfakir, Claire; Lafosse, Michel

2005-07-22

A new procedure based on hydrophilic interaction chromatography coupled to tandem mass spectrometry (ionisation process by pneumatically assisted electrospray in negative ion mode), is developed and validated for the simultaneous determination of underivatised taurine and methionine in beverages rich in carbohydrates such as energy drinks. No initial clean-up procedure and no sample derivatisation are required. Satisfactory analysis was obtained on an Astec apHera NH2 (150 mm x 4.6 mm; 5 microm) column with methanol-water (60/40) as mobile phase. The method was validated in terms of specificity, detection limits, linearity, accuracy, precision and stability, using threonine as internal standard. The potential effects of matrix and endogenous amino acid content were also examined. The limits of detection in the beverage varied from 20 microg L(-1) for taurine to 50 micro L(-1) for methionine.

Liquid chromatographic separation of zalcitabine and its stereoisomers.

PubMed

Scypinski, S; Ross, A J

1994-10-01

A liquid chromatographic method capable of separating and quantitating the stereoisomers of zalcitabine has been developed and validated. The separation was achieved with an Astec Cyclobond I--RSP column and a mobile phase of 0.25% triethylamine in water adjusted to a pH of 6.5 with glacial acetic acid. All enantiomers were found to exhibit a linear response in the range of 0.1-10% in the presence of 100% zalcitabine. Precision of analysis was found to be less than 1.5% at a level of 1% relative to zalcitabine. The limit of detection for two of the three enantiomeric impurities was determined to be 0.05% relative to zalcitabine. The detection limit for the third was found to be 0.1%. This method was successfully applied to the analysis of reference standards and several production scale batches. All of these materials were found to be stereochemically pure to a level of 99.8% or better.

ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes.

PubMed

Ghorbani, Ramin; Schmidt, Florian M

2017-05-29

We present a compact sensor for carbon monoxide (CO) in air and exhaled breath based on a room temperature interband cascade laser (ICL) operating at 4.69 µm, a low-volume circular multipass cell and wavelength modulation absorption spectroscopy. A fringe-limited (1σ) sensitivity of 6.5 × 10 -8 cm -1 Hz -1/2 and a detection limit of 9 ± 5 ppbv at 0.07 s acquisition time are achieved, which constitutes a 25-fold improvement compared to direct absorption spectroscopy. Integration over 10 s increases the precision to 0.6 ppbv. The setup also allows measuring the stable isotope 13 CO in breath. We demonstrate quantification of indoor air CO and real-time detection of CO expirograms from healthy non-smokers and a healthy smoker before and after smoking. Isotope ratio analysis indicates depletion of 13 CO in breath compared to natural abundance.

Environmental applications of single collector high resolution ICP-MS.

PubMed

Krachler, Michael

2007-08-01

The number of environmental applications of single collector high resolution ICP-MS (HR-ICP-MS) has increased rapidly in recent years. There are many factors that contribute to make HR-ICP-MS a very powerful tool in environmental analysis. They include the extremely low detection limits achievable, tremendously high sensitivity, the ability to separate ICP-MS signals of the analyte from spectral interferences, enabling the reliable determination of many trace elements, and the reasonable precision of isotope ratio measurements. These assets are improved even further using high efficiency sample introduction systems. Therefore, external factors such as the stability of laboratory blanks are frequently the limiting factor in HR-ICP-MS analysis rather than the detection power. This review aims to highlight the most recent applications of HR-ICP-MS in this sector, focusing on matrices and applications where the superior capabilities of the instrumental technique are most useful and often ultimately required.

Determination of enrofloxacin by room-temperature phosphorimetry after solid phase extraction on an acrylic polymer sorbent

NASA Astrophysics Data System (ADS)

de Souza, Cabrini F.; Martins, Renata K. S.; da Silva, Andrea R.; da Cunha, Alessandra L. M. C.; Aucélio, Ricardo Q.

A phosphorimetric method was developed to enable the determination of enrofloxacin using photochemical derivatization which was used to both improve detection limits and to minimize the uncertainty of measurements. Phosphorescence was induced on cellulose containing TlNO3. Absolute limit of detection at the ng range and linear analytical response over three orders of magnitude were achieved. A metrological study was made to obtain the combined uncertainty value and to identify that the precision was mainly affected by the changing of substrates when measuring the signal from each replicate. Pharmaceutical formulations containing enrofloxacin were successfully analyzed by the method and the results were similar to the ones achieved using a HPLC method. A solid phase extraction on an acrylic polymer was optimized to separate enrofloxacin from interferents such as diclofenac and other components from biological matrices, which allowed the successful use of the method in urine analysis.

High-performance liquid chromatographic assay for the determination of Aloe Emodin in mouse plasma.

PubMed

Zaffaroni, M; Mucignat, C; Pecere, T; Zagotto, G; Frapolli, R; D'Incalci, M; Zucchetti, M

2003-10-25

An isocratic high-performance liquid chromatography (HPLC) method was developed and validated to determine Aloe Emodin (AE) in mouse plasma. The analysis required 0.3 ml of plasma and involves extraction with dichloromethane. The HPLC separation was carried out on Symmetry Shield RP18, a mobile phase of methanol-water-acetic acid (65:35:0.2) and fluorescence detection at lambda(ex)=410 nm and lambda(em)=510 nm. The retention time of AE was 11.7 min. The assay was linear from 10 to 1,000 ng/ml (r2 > or = 0.999), showed intra- and inter-day precision within 7.8 and 4.7%, and accuracy of 87.3-105.7%. Detection limit (LOD) and quantification limit (LOQ) were 4.5 and 5 ng/ml, respectively. The method was applied to determine for the first time the pharmacokinetic of AE in mice.

Julius Edgar Lilienfeld Prize Talk: Measuring the Electron Magnetic Moment and the Fine Structure Constant

NASA Astrophysics Data System (ADS)

Gabrielse, Gerald

2011-05-01

The electron magnetic moment in Bohr magnetons has been measured to a precision of 3 parts in 1013. This measurement, with quantum electrodynamics (AED) theory, provides the most precise value of the fine structure constant. This measurement, with a value of the fine structure from other measurements, also tests QED and sets a limit on the internal structure of the electron. A one-electron quantum cyclotron is at the heart of the measurement -- an electron suspended in a magnetic field and cooled enough that its lowest cyclotron and spin quantum states can be deduced with quantum nondemolition (QND) measurements. A cylindrical Penning trap cavity inhibits spontaneous emission and feedback methods make the electron excite and sustain its own motion for detection. A new apparatus is being commissioned in pursuit of more precise measurements. Adapted methods are promising for observing a proton spin flip, which should make it possible to compare the antiproton and proton magnetic moments a million times more accurately than is currently possible.

GFAAS determination of selenium in infant formulas using a microwave digestion method.

PubMed

Alegria, A; Barbera, R; Farré, R; Moreno, A

1994-01-01

A method for determining the selenium content of infant formulas is proposed. It includes wet digestion with nitric acid and hydrogen peroxide in medium pressure teflon bombs in a microwave oven and determination by graphite furnace atomic absorption spectrometry (GFAAS). The absence of interferences is checked. Values obtained for the limit of detection (19.4 ng/g), precision (RSD = 2.2%) and accuracy by analysis of a reference material show that the method is reliable.

Simultaneous determination three phytosterol compounds, campesterol, stigmasterol and daucosterol in Artemisia apiacea by high performance liquid chromatography-diode array ultraviolet/visible detector.

PubMed

Lee, Jiwoo; Weon, Jin Bae; Yun, Bo-Ra; Eom, Min Rye; Ma, Choong Je

2015-01-01

Artemisia apiacea is a traditional herbal medicine using treatment of eczema and jaundice in Eastern Asia, including China, Korea, and Japan. An accurate and sensitive analysis method using high performance liquid chromatography-diode array ultraviolet/visible detector and liquid chromatography-mass spectrometry for the simultaneous determination of three phytosterol compounds, campesterol, stigmasterol and daucosterol in A. apiacea was established. The analytes were separated on a Shiseido C18 column (5 μm, 4.6 mm I.D. ×250 mm) with gradient elution of 0.1% trifluoroacetic acid and acetonitrile. The flow rate was 1 mL/min and detection wavelengths were set at 205 and 254 nm. Validation of the method was performed to demonstrate its linearity, precision and accuracy. The calibration curves showed good linearity (R (2) > 0.9994). The limits of detection and limits of quantification were within the ranges 0.55-7.07 μg/mL and 1.67-21.44 μg/mL, respectively. And, the relative standard deviations of intra- and inter-day precision were <2.93%. The recoveries were found to be in the range of 90.03-104.91%. The developed method has been successfully applied to the analysis for quality control of campesterol, stigmasterol and daucosterol in A. apiacea.

Magnetic graphene coated inorganic-organic hybrid nanocomposite for enhanced preconcentration of selected pesticides in tomato and grape.

PubMed

Rashidi Nodeh, Hamid; Sereshti, Hassan; Gaikani, Hamid; Kamboh, Muhammad Afzal; Afsharsaveh, Zahra

2017-08-04

The new magnetic graphene based hybrid silica-N-[3-(trimethoxysilyl)propyl]ethylenediamine (MG@SiO 2 -TMSPED) nanocomposite was synthesized via sol-gel process, and used as an effective adsorbent in magnetic solid phase extraction (MSPE) of three selected pesticides followed by gas chromatography micro-electron capture detection (GC-μECD). The adsorbent was characterized using Fourier transform-infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDXS) techniques. The analytical validity of the developed method was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 1-20μgkg -1 with good determination coefficients (R 2 =0.995-0.999); limits of detection (LODs), 0.23-0.30μgkg -1 (3×SD/m, n=3); and limits of quantitation (LOQ), 0.76-1.0μgkg -1 (10×SD/m, n=3). The precision (RSD%) of the proposed MSPE method was studied based on intra-day (3.43-8.83%, n=3) and inter-day (6.68-8.37%, n=12) precisions. Finally, the adsorbent was applied to determination of pesticides in tomato and grape samples and good recoveries were obtained in the range from 82 to 113% (RSDs 5.1-8.1%, n=3). Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination three phytosterol compounds, campesterol, stigmasterol and daucosterol in Artemisia apiacea by high performance liquid chromatography-diode array ultraviolet/visible detector

PubMed Central

Lee, Jiwoo; Weon, Jin Bae; Yun, Bo-Ra; Eom, Min Rye; Ma, Choong Je

2015-01-01

Background: Artemisia apiacea is a traditional herbal medicine using treatment of eczema and jaundice in Eastern Asia, including China, Korea, and Japan. Objective: An accurate and sensitive analysis method using high performance liquid chromatography-diode array ultraviolet/visible detector and liquid chromatography–mass spectrometry for the simultaneous determination of three phytosterol compounds, campesterol, stigmasterol and daucosterol in A. apiacea was established. Materials and Methods: The analytes were separated on a Shiseido C18 column (5 μm, 4.6 mm I.D. ×250 mm) with gradient elution of 0.1% trifluoroacetic acid and acetonitrile. The flow rate was 1 mL/min and detection wavelengths were set at 205 and 254 nm. Results: Validation of the method was performed to demonstrate its linearity, precision and accuracy. The calibration curves showed good linearity (R2 > 0.9994). The limits of detection and limits of quantification were within the ranges 0.55–7.07 μg/mL and 1.67–21.44 μg/mL, respectively. And, the relative standard deviations of intra- and inter-day precision were <2.93%. The recoveries were found to be in the range of 90.03–104.91%. Conclusion: The developed method has been successfully applied to the analysis for quality control of campesterol, stigmasterol and daucosterol in A. apiacea. PMID:25829768

Multimycotoxin LC-MS/MS Analysis in Tea Beverages after Dispersive Liquid-Liquid Microextraction (DLLME).

PubMed

Pallarés, Noelia; Font, Guillermina; Mañes, Jordi; Ferrer, Emilia

2017-11-29

The aim of the present study was to develop a multimycotoxin liquid chromatography tandem mass spectrometry (LC-MS/MS) method with a dispersive liquid-liquid microextraction procedure (DLLME) for the analysis of AFs, 3aDON, 15aDON, NIV, HT-2, T-2, ZEA, OTA, ENNs, and BEA in tea beverages and to evaluate their mycotoxin contents. The proposed method was characterized in terms of linearity, limits of detection (LODs), limits of quantification (LOQs), recoveries, repeatability (intraday precision), reproducibility (interday precision), and matrix effects to check suitability. The results show LODs in the range of 0.05-10 μg/L, LOQs in the range of 0.2-33 μg/L, and recoveries in the range of 65-127% (RSD < 20%). The method developed in this study was applied to 44 commercial samples of black tea, red tea, green tea, and green mint tea. The results show that, of the analyzed mycotoxins, AFB2, AFG2, 15aDON, AFG1, and ENB were detected in the samples. AFB2 (14.4-32.2 μg/L) and 15aDON (60.5-61 μg/L) presented the highest levels. Green mint tea contained the highest concentration of mycotoxins. The risk assessment study shows that the population is not much exposed to mycotoxins through the consumption of tea beverages.

Development and Validation of a Simultaneous RP-HPLCUV/DAD Method for Determination of Polyphenols in Gels Containing S. terebinthifolius Raddi (Anacardiaceae)

PubMed Central

Carvalho, Melina G.; Aragão, Cícero F. S; Raffin, Fernanda N.; de L. Moura, Túlio F. A.

2017-01-01

Topical gels containing extracts of Schinus terebinthifolius have been used to treat bacterial vaginosis. It has been reported that this species has antimicrobial, anti-inflammatory and anti-ulcerogenic properties, which can be attributed to the presence of phenolic compounds. In this work, a sensitive and selective reversed-phase HPLC-UV/DAD method for the simultaneous assay of six polyphenols that could be present in S. terebinthifolius was developed. The method was shown to be accurate and precise. Peak purity and similarity index both exceeded 0.99. Calibration curves were linear over the concentration range studied, with correlation coefficients between 0.9931 and 0.9974. This method was used to determine the polyphenol content of a hydroalcoholic extract and pharmacy-compounded vaginal gel. Although the method is useful to assess the 6 phenolic compounds, some compounds could not be detected in the products. SUMMARY A sensitive, selective, accurate and precise reversed-phase HPLC-UV/DAD method for the simultaneous assay of six polyphenols in S. terebinthifolius Raddi Abbreviations used: RP-HPLC-UV/DAD: Reverse Phase High Performance Liquid Chromatograph with Ultraviolet and Diode Array Detector, HPLC: High Performance Liquid Chromatograph, HPLC-UV: High Performance Liquid Chromatograph with Ultraviolet Detector, ANVISA: Brazilian National Health Surveillance Agency, LOD: Limit of detection, LOQ: Limit of quantitation PMID:28539726

Stability of suxamethonium in pharmaceutical solution for injection by validated stability-indicating chromatographic method.

PubMed

Beck, William; Kabiche, Sofiane; Balde, Issa-Bella; Carret, Sandra; Fontan, Jean-Eudes; Cisternino, Salvatore; Schlatter, Joël

2016-12-01

To assess the stability of pharmaceutical suxamethonium (succinylcholine) solution for injection by validated stability-indicating chromatographic method in vials stored at room temperature. The chromatographic assay was achieved by using a detector wavelength set at 218 nm, a C18 column, and an isocratic mobile phase (100% of water) at a flow rate of 0.6 mL/min for 5 minutes. The method was validated according to the International Conference on Harmonization guidelines with respect to the stability-indicating capacity of the method including linearity, limits of detection and quantitation, precision, accuracy, system suitability, robustness, and forced degradations. Linearity was achieved in the concentration range of 5 to 40 mg/mL with a correlation coefficient higher than 0.999. The limits of detection and quantification were 0.8 and 0.9 mg/mL, respectively. The percentage relative standard deviation for intraday (1.3-1.7) and interday (0.1-2.0) precision was found to be less than 2.1%. Accuracy was assessed by the recovery test of suxamethonium from solution for injection (99.5%-101.2%). Storage of suxamethonium solution for injection vials at ambient temperature (22°C-26°C) for 17 days demonstrated that at least 95% of original suxamethonium concentration remained stable. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of itopride hydrochloride in human plasma by RP-HPLC with fluorescence detection and its use in bioequivalence study.

PubMed

Ma, Jing; Yuan, Li-Hua; Ding, Mei-Juan; Zhang, Jun; Zhang, Qing; Xu, Qun-Wei; Zhou, Xue-Min

2009-03-01

A sensitive, selective and simple method using a precipitation of protein with 10% perchloric acid, followed by high-performance liquid chromatography (HPLC) with fluorescence detection was developed for the determination of itopride hydrochloride in human plasma, using levofloxacin as the internal standard (IS). Chromatographic separation was obtained within 7.0 min using a reverse phase Hypersil BDS C(18) (250 mm x 4.6 mm, 5 microm) column and an isocratic mobile phase, constituting of a mixture of 0.1 mol/l ammonium acetate-methanol (30:70, v/v) flowing at 1.1 ml/min. The excitation and emission wavelengths were set at 304 and 344 nm, respectively. The method was validated over the concentration range of 5 ng/ml to 1000.0 ng/ml. The lower limit of quantitation (LLOQ) was 5 ng/ml. The extractive recovery of itopride hydrochloride from the biological matrix was more than 80.77%. The intra-day accuracy of the drug containing serum samples was more than 82.94% with a precision of 2.81-4.37%. The inter-day accuracy was 82.91% or more, with a precision of 6.89-9.54%. The limit we have used (70-143%) is based on the local regulatory authority (SFDA). The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers.

Development of paper-based sensor coupled with smartphone detector for simple creatinine determination

NASA Astrophysics Data System (ADS)

Tambaru, David; Rupilu, Reski Helena; Nitti, Fidelis; Gauru, Imanuel; Suwari

2017-03-01

Creatinine level in urine is one of the most important indicators for kidney diseases. A routine assay for this compound is vital especially for those who suffer from kidney malfunction. However, the existing methods are mostly expensive, impractical and time consuming. Here in, we report a research on the development of sensor for creatinine analysis by using cheap materials such as paper and coupled with a smartphone as the detector leading to an inexpensive and free-instrument method. This research was done based on the Jaffe reaction in which the creatinine was reacted with picric acid in basic solution to form an orange-red creatinine-picric complex. The red-green-blue intensity of the complex, captured with a smartphone, was measured and then digitized with free-download Microsoft Visual c# 2010I Express applications, as the analytical response. This proposed method was evaluated based on its precision, accuracy, percent of recovery and limit of detection. It was found that the precision, accuracy, percent of recovery and limit of detection of this method were 5.55%, 0.74 %, 96.73 ± 6.12 % and 8.02 ppm, respectively. It can be concluded that the paper based sensors with digital imaging approach using Microsoft Visual c# 2010I Express,with its simplicity and affordabilitycan be applied for on-site determination of creatinine level.

Sternal instability measured with radiostereometric analysis. A study of method feasibility, accuracy and precision.

PubMed

Vestergaard, Rikke Falsig; Søballe, Kjeld; Hasenkam, John Michael; Stilling, Maiken

2018-05-18

A small, but unstable, saw-gap may hinder bone-bridging and induce development of painful sternal dehiscence. We propose the use of Radiostereometric Analysis (RSA) for evaluation of sternal instability and present a method validation. Four bone analogs (phantoms) were sternotomized and tantalum beads were inserted in each half. The models were reunited with wire cerclage and placed in a radiolucent separation device. Stereoradiographs (n = 48) of the phantoms in 3 positions were recorded at 4 imposed separation points. The accuracy and precision was compared statistically and presented as translations along the 3 orthogonal axes. 7 sternotomized patients were evaluated for clinical RSA precision by double-examination stereoradiographs (n = 28). In the phantom study, we found no systematic error (p > 0.3) between the three phantom positions, and precision for evaluation of sternal separation was 0.02 mm. Phantom accuracy was mean 0.13 mm (SD 0.25). In the clinical study, we found a detection limit of 0.42 mm for sternal separation and of 2 mm for anterior-posterior dislocation of the sternal halves for the individual patient. RSA is a precise and low-dose image modality feasible for clinical evaluation of sternal stability in research. ClinicalTrials.gov Identifier: NCT02738437 , retrospectively registered.

An in-house assay for BK polyomavirus quantification using the Abbott m2000 RealTime system.

PubMed

Muldrew, Kenneth L; Lovett, Jennie L

2013-11-01

BK polyomavirus (BKPyV) quantification is useful for monitoring renal transplant patient response to therapy. The Abbott m2000 RealTime System employed by some clinical laboratories to perform US Food and Drug Administration-approved assays can also be used to develop in-house assays such as the one presented here. This study aimed to validate an in-house quantitative real-time PCR assay targeting the BKPyV major capsid VP1 gene for assessment of viral load using the Abbott m2000 RealTime System. BKPyV load was measured in 95 urine and plasma samples previously tested for BKPyV by one of three laboratories (46 BKPyV-positive samples consisting of 35 plasma and 11 urine samples; 49 samples negative for BKPyV consisting of 47 plasma and two urine samples). Two additional plasma specimens from the College of American Pathologists proficiency testing survey were also analysed. Precision studies were performed by diluting a high-viral-titre patient sample into BKPyV-negative pooled plasma to create high-positive (6.16 log10 copies ml(-1)) and low-positive (3.16 log10 copies ml(-1)) samples. For precision studies of inter-assay variability, a high-positive (7.0 log10 copies ml(-1)) and a low-positive (3.0 log10 copies ml(-1)) sample were measured in 20 separate runs. The assay's limit of quantification and limit of detection were 2.70 and 2.25 log10 copies ml(-1), respectively. The assay was linear from 2.70 to 9.26 log10 copies ml(-1). Of the 48 known positives, 43 were detected as positive, with three reported by the reference laboratory as values lower than the limit of detection. Two known positives at 3.27 and 3.80 log10 copies ml(-1) tested negative by the m2000 BKPyV assay. Of the 49 known negative samples, 48 were negative by the m2000 BKPyV load assay, with one sample confirmed positive by a reference laboratory. Qualitative analysis prior to discrepancy testing demonstrated a sensitivity of 89.58 % and a specificity of 97.96 %. Precision studies demonstrated inter-assay coefficients of variation of 0.63 % (high positive) and 4.38 % (low positive). Genotyping was performed on 22 patient samples, of which 21 (95.45 %) were type I and one (4.55 %) was type II. In conclusion, the m2000 BKPyV viral load assay sensitivity, specificity, linear range, precision and cost effectiveness make it an attractive methodology for clinical laboratories using the Abbott m2000 RealTime System.

Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics.

PubMed

Inci, Fatih; Filippini, Chiara; Baday, Murat; Ozen, Mehmet Ozgun; Calamak, Semih; Durmus, Naside Gozde; Wang, ShuQi; Hanhauser, Emily; Hobbs, Kristen S; Juillard, Franceline; Kuang, Ping Ping; Vetter, Michael L; Carocci, Margot; Yamamoto, Hidemi S; Takagi, Yuko; Yildiz, Umit Hakan; Akin, Demir; Wesemann, Duane R; Singhal, Amit; Yang, Priscilla L; Nibert, Max L; Fichorova, Raina N; Lau, Daryl T-Y; Henrich, Timothy J; Kaye, Kenneth M; Schachter, Steven C; Kuritzkes, Daniel R; Steinmetz, Lars M; Gambhir, Sanjiv S; Davis, Ronald W; Demirci, Utkan

2015-08-11

Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE(2)RD), which addresses all these impediments on a single platform. The NE(2)RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE(2)RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE(2)RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients' homes.

Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics

PubMed Central

Inci, Fatih; Filippini, Chiara; Ozen, Mehmet Ozgun; Calamak, Semih; Durmus, Naside Gozde; Wang, ShuQi; Hanhauser, Emily; Hobbs, Kristen S.; Juillard, Franceline; Kuang, Ping Ping; Vetter, Michael L.; Carocci, Margot; Yamamoto, Hidemi S.; Takagi, Yuko; Yildiz, Umit Hakan; Akin, Demir; Wesemann, Duane R.; Singhal, Amit; Yang, Priscilla L.; Nibert, Max L.; Fichorova, Raina N.; Lau, Daryl T.-Y.; Henrich, Timothy J.; Kaye, Kenneth M.; Schachter, Steven C.; Kuritzkes, Daniel R.; Steinmetz, Lars M.; Gambhir, Sanjiv S.; Davis, Ronald W.; Demirci, Utkan

2015-01-01

Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients’ homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE2RD), which addresses all these impediments on a single platform. The NE2RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE2RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE2RD’s broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients’ homes. PMID:26195743

Resolving discrete pulsar spin-down states with current and future instrumentation

NASA Astrophysics Data System (ADS)

Shaw, B.; Stappers, B. W.; Weltevrede, P.

2018-04-01

An understanding of pulsar timing noise offers the potential to improve the timing precision of a large number of pulsars as well as facilitating our understanding of pulsar magnetospheres. For some sources, timing noise is attributable to a pulsar switching between two different spin-down rates (\\dot{ν }). Such transitions may be common but difficult to resolve using current techniques. In this work, we use simulations of \\dot{ν }-variable pulsars to investigate the likelihood of resolving individual \\dot{ν } transitions. We inject step changes in the value of \\dot{ν } with a wide range of amplitudes and switching time-scales. We then attempt to redetect these transitions using standard pulsar timing techniques. The pulse arrival-time precision and the observing cadence are varied. Limits on \\dot{ν } detectability based on the effects such transitions have on the timing residuals are derived. With the typical cadences and timing precision of current timing programmes, we find that we are insensitive to a large region of Δ \\dot{ν } parameter space that encompasses small, short time-scale switches. We find, where the rotation and emission states are correlated, that using changes to the pulse shape to estimate \\dot{ν } transition epochs can improve detectability in certain scenarios. The effects of cadence on Δ \\dot{ν } detectability are discussed, and we make comparisons with a known population of intermittent and mode-switching pulsars. We conclude that for short time-scale, small switches, cadence should not be compromised when new generations of ultra-sensitive radio telescopes are online.

UV Spectrophotometric Method for Estimation of Polypeptide-K in Bulk and Tablet Dosage Forms

NASA Astrophysics Data System (ADS)

Kaur, P.; Singh, S. Kumar; Gulati, M.; Vaidya, Y.

2016-01-01

An analytical method for estimation of polypeptide-k using UV spectrophotometry has been developed and validated for bulk as well as tablet dosage form. The developed method was validated for linearity, precision, accuracy, specificity, robustness, detection, and quantitation limits. The method has shown good linearity over the range from 100.0 to 300.0 μg/ml with a correlation coefficient of 0.9943. The percentage recovery of 99.88% showed that the method was highly accurate. The precision demonstrated relative standard deviation of less than 2.0%. The LOD and LOQ of the method were found to be 4.4 and 13.33, respectively. The study established that the proposed method is reliable, specific, reproducible, and cost-effective for the determination of polypeptide-k.

Detecting signals of detrimental prescribing cascades from social media.

PubMed

Hoang, Tao; Liu, Jixue; Pratt, Nicole; Zheng, Vincent W; Chang, Kevin C; Roughead, Elizabeth; Li, Jiuyong

2016-07-01

Prescribing cascade (PC) occurs when an adverse drug reaction (ADR) is misinterpreted as a new medical condition, leading to further prescriptions for treatment. Additional prescriptions, however, may worsen the existing condition or introduce additional adverse effects (AEs). Timely detection and prevention of detrimental PCs is essential as drug AEs are among the leading causes of hospitalization and deaths. Identifying detrimental PCs would enable warnings and contraindications to be disseminated and assist the detection of unknown drug AEs. Nonetheless, the detection is difficult and has been limited to case reports or case assessment using administrative health claims data. Social media is a promising source for detecting signals of detrimental PCs due to the public availability of many discussions regarding treatments and drug AEs. In this paper, we investigate the feasibility of detecting detrimental PCs from social media. The detection, however, is challenging due to the data uncertainty and data rarity in social media. We propose a framework to mine sequences of drugs and AEs that signal detrimental PCs, taking into account the data uncertainty and data rarity. We conduct experiments on two real-world datasets collected from Twitter and Patient health forum. Our framework achieves encouraging results in the validation against known detrimental PCs (F1=78% for Twitter and 68% for Patient) and the detection of unknown potential detrimental PCs (Precision@50=72% and NDCG@50=95% for Twitter, Precision@50=86% and NDCG@50=98% for Patient). In addition, the framework is efficient and scalable to large datasets. Our study demonstrates the feasibility of generating hypotheses of detrimental PCs from social media to reduce pharmacists' guesswork. Copyright © 2016 Elsevier B.V. All rights reserved.

Real-time breath gas analysis of CO and CO2 using an EC-QCL

NASA Astrophysics Data System (ADS)

Ghorbani, Ramin; Schmidt, Florian M.

2017-05-01

Real-time breath gas analysis is a promising, non-invasive tool in medical diagnostics, and well-suited to investigate the physiology of carbon monoxide (CO), a potential biomarker for oxidative stress and respiratory diseases. A sensor for precise, breath-cycle resolved, simultaneous detection of exhaled CO (eCO) and carbon dioxide (eCO2) was developed based on a continuous wave, external-cavity quantum cascade laser (EC-QCL), a low-volume multi-pass cell and wavelength modulation spectroscopy. The system achieves a noise-equivalent (1σ) sensitivity of 8.5 × 10-8 cm-1 Hz-1/2 and (2σ) detection limits of 9 ± 2 ppbv and 650 ± 7 ppmv at 0.14 s spectrum acquisition time for CO and CO2, respectively. Integration over 15 s yields a precision of 0.6 ppbv for CO. The fact that the eCO2 expirograms measured by capnography and laser spectroscopy have essentially identical shape confirms true real-time detection. It is found that the individual eCO exhalation profiles from healthy non-smokers have a slightly different shape than the eCO2 profiles and exhibit a clear dependence on exhalation flow rate and breath-holding time. Detection of indoor air CO and broadband breath profiling across the 93 cm-1 mode-hop-free tuning range of the EC-QCL are also demonstrated.

Rapid determination of letrozole, citalopram and their metabolites by high performance liquid chromatography-fluorescence detection in urine: Method validation and application to real samples.

PubMed

Rodríguez, J; Castañeda, G; Muñoz, L

2013-01-15

This work reports the validation of a high precision and accuracy method for the simultaneous determination of letrozole, citalopram and their metabolites in urine by high performance liquid chromatography with fluorescence detection. Dilution (urine:mobile phase, 1:2, v/v) was the only sample preparation step. The separation was carried out in a Kromasil C(18) (150mm×4.6mm) column, and the mobile phase was phosphate buffer 80mM (pH 3.0) and acetonitrile (65:35, v/v) at a flow rate of 1.0mL/min. The analytes were detected at 295nm after excitation at 230nm. Linearity was observed in the range of 1.0-1000ng/mL for letrozole and its metabolite and 2.5-1000ng/mL for citalopram and their metabolites, with limits of detection and quantification between 0.09-1.0 and 0.27-1.65ng/mL, respectively. The precisions were satisfactory with RSDs between 0.17 and 5.71%. The accuracy was studied by spiking three urines from healthy female volunteers, and the recoveries were from 85 to 103%. The method was applied to urine samples from women under treatment for breast cancer and depression diseases. Copyright © 2012 Elsevier B.V. All rights reserved.

Quantum sensing with arbitrary frequency resolution

NASA Astrophysics Data System (ADS)

Boss, J. M.; Cujia, K. S.; Zopes, J.; Degen, C. L.

2017-05-01

Quantum sensing takes advantage of well-controlled quantum systems for performing measurements with high sensitivity and precision. We have implemented a concept for quantum sensing with arbitrary frequency resolution, independent of the qubit probe and limited only by the stability of an external synchronization clock. Our concept makes use of quantum lock-in detection to continuously probe a signal of interest. Using the electronic spin of a single nitrogen-vacancy center in diamond, we demonstrate detection of oscillating magnetic fields with a frequency resolution of 70 microhertz over a megahertz bandwidth. The continuous sampling further guarantees an enhanced sensitivity, reaching a signal-to-noise ratio in excess of 104 for a 170-nanotesla test signal measured during a 1-hour interval. Our technique has applications in magnetic resonance spectroscopy, quantum simulation, and sensitive signal detection.

Adaptive distributed outlier detection for WSNs.

PubMed

De Paola, Alessandra; Gaglio, Salvatore; Lo Re, Giuseppe; Milazzo, Fabrizio; Ortolani, Marco

2015-05-01

The paradigm of pervasive computing is gaining more and more attention nowadays, thanks to the possibility of obtaining precise and continuous monitoring. Ease of deployment and adaptivity are typically implemented by adopting autonomous and cooperative sensory devices; however, for such systems to be of any practical use, reliability and fault tolerance must be guaranteed, for instance by detecting corrupted readings amidst the huge amount of gathered sensory data. This paper proposes an adaptive distributed Bayesian approach for detecting outliers in data collected by a wireless sensor network; our algorithm aims at optimizing classification accuracy, time complexity and communication complexity, and also considering externally imposed constraints on such conflicting goals. The performed experimental evaluation showed that our approach is able to improve the considered metrics for latency and energy consumption, with limited impact on classification accuracy.

Weighing Rocky Exoplanets with Improved Radial Velocimetry

NASA Astrophysics Data System (ADS)

Xuesong Wang, Sharon; Wright, Jason; California Planet Survey Consortium

2016-01-01

The synergy between Kepler and the ground-based radial velocity (RV) surveys have made numerous discoveries of small and rocky exoplanets, opening the age of Earth analogs. However, most (29/33) of the RV-detected exoplanets that are smaller than 3 Earth radii do not have their masses constrained to better than 20% - limited by the current RV precision (1-2 m/s). Our work improves the RV precision of the Keck telescope, which is responsible for most of the mass measurements for small Kepler exoplanets. We have discovered and verified, for the first time, two of the dominant terms in Keck's RV systematic error budget: modeling errors (mostly in deconvolution) and telluric contamination. These two terms contribute 1 m/s and 0.6 m/s, respectively, to the RV error budget (RMS in quadrature), and they create spurious signals at periods of one sidereal year and its harmonics with amplitudes of 0.2-1 m/s. Left untreated, these errors can mimic the signals of Earth-like or Super-Earth planets in the Habitable Zone. Removing these errors will bring better precision to ten-year worth of Keck data and better constraints on the masses and compositions of small Kepler planets. As more precise RV instruments coming online, we need advanced data analysis tools to overcome issues like these in order to detect the Earth twin (RV amplitude 8 cm/s). We are developing a new, open-source RV data analysis tool in Python, which uses Bayesian MCMC and Gaussian processes, to fully exploit the hardware improvements brought by new instruments like MINERVA and NASA's WIYN/EPDS.

The bias, accuracy and precision of faecal egg count reduction test results in cattle using McMaster, Cornell-Wisconsin and FLOTAC egg counting methods.

PubMed

Levecke, B; Rinaldi, L; Charlier, J; Maurelli, M P; Bosco, A; Vercruysse, J; Cringoli, G

2012-08-13

The faecal egg count reduction test (FECRT) is the recommended method to monitor anthelmintic drug efficacy in cattle. There is a large variation in faecal egg count (FEC) methods applied to determine FECRT. However, it remains unclear whether FEC methods with an equal analytic sensitivity, but with different methodologies, result in equal FECRT results. We therefore, compared the bias, accuracy and precision of FECRT results for Cornell-Wisconsin (analytic sensitivity = 1 egg per gram faeces (EPG)), FLOTAC (analytic sensitivity = 1 EPG) and McMaster method (analytic sensitivity = 10 EPG) across four levels of egg excretion (1-49 EPG; 50-149 EPG; 150-299 EPG; 300-600 EPG). Finally, we assessed the sensitivity of the FEC methods to detect a truly reduced efficacy. To this end, two different criteria were used to define reduced efficacy based on FECR, including those described in the WAAVP guidelines (FECRT <95% and lower limit of 95%CI <90%) (Coles et al., 1992) and those proposed by El-Abdellati et al. (2010) (upper limit of 95%CI <95%). There was no significant difference in bias and accuracy of FECRT results across the three methods. FLOTAC provided the most precise FECRT results. Cornell-Wisconsin and McMaster gave similar imprecise results. FECRT were significantly underestimated when baseline FEC were low and drugs were more efficacious. For all FEC methods, precision and accuracy of the FECRT improved as egg excretion increased, this effect was greatest for McMaster and least for Cornell-Wisconsin. The sensitivity of the three methods to detect a truly reduced efficacy was high (>90%). Yet, the sensitivity of McMaster and Cornell-Wisconsin may drop when drugs only show sub-optimal efficacy. Overall, the study indicates that the precision of FECRT is affected by the methodology of FEC, and that the level of egg excretion should be considered in the final interpretation of the FECRT. However, more comprehensive studies are required to provide more insights into the complex interplay of factors inherent to study design (sample size and FEC method) and host-parasite interactions (level of egg excretion and aggregation across the host population). Copyright © 2012 Elsevier B.V. All rights reserved.

Validation of the Cepheid GeneXpert for Detecting Ebola Virus in Semen.

PubMed

Loftis, Amy James; Quellie, Saturday; Chason, Kelly; Sumo, Emmanuel; Toukolon, Mason; Otieno, Yonnie; Ellerbrok, Heinzfried; Hobbs, Marcia M; Hoover, David; Dube, Karine; Wohl, David A; Fischer, William A

2017-02-01

Ebola virus (EBOV) RNA persistence in semen, reported sexual transmission, and sporadic clusters at the end of the 2013-2016 epidemic have prompted recommendations that male survivors refrain from unprotected sex unless their semen is confirmed to be EBOV free. However, there is no fully validated assay for EBOV detection in fluids other than blood. The Cepheid Xpert Ebola assay for EBOV RNA detection was validated for whole semen and blood using samples obtained from uninfected donors and spiked with inactivated EBOV. The validation procedure incorporated standards from Clinical and Laboratory Standards Institute and Good Clinical Laboratory Practices guidelines for evaluating molecular devices for use in infectious disease testing. The assay produced limits of detection of 1000 copies/mL in semen and 275 copies/mL in blood. Limits of detection for both semen and blood increased with longer intervals between collection and testing, with acceptable results obtained up to 72 hours after specimen collection. The Cepheid Xpert Ebola assay is accurate and precise for detecting EBOV in whole semen. A validated assay for EBOV RNA detection in semen informs the care of male survivors of Ebola, as well as recommendations for public health. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Phosphate determination in seawater: toward an autonomous electrochemical method.

PubMed

Jońca, Justyna; León Fernández, Violeta; Thouron, Danièle; Paulmier, Aurélien; Graco, Michelle; Garçon, Véronique

2011-12-15

Initial steps to create an autonomous in situ electrochemical sensor for orthophosphate determination in seawater are presented. First, the optimal conditions to form the molybdophosphate complex in artificial seawater medium were determined by addition of sulphuric acid and sodium molybdate to the solution containing orthophosphate. Secondly, the anodic oxidation of molybdenum to form molybdate ions and protons was used to create the molybdophosphate complex without addition of any liquid reagents. The molybdophosphate complex is detectable by amperometry with an average precision of 2.2% for the concentration range found in the open ocean and the detection limit is 0.12 μM. Three solutions are proposed to address the silicate interferences issue and one of these methods is used for the natural samples collected in the coastal waters offshore Peru during the Pelagico 1011-12-BIC OLAYA cruise in November-December 2010. Results showed a good precision with an average of 2.5% and a reasonable deviation of the amperometric analysis as compared with colorimetric measurements (4.9%). Copyright © 2011 Elsevier B.V. All rights reserved.

Immunoturbidimetric assay for estimating free light chains of immunoglobulins in urine and serum.

PubMed Central

Tillyer, C R; Iqbal, J; Raymond, J; Gore, M; McIlwain, T J

1991-01-01

An immunoturbidimetric assay for the assessment of free kappa and lambda light chains of immunoglobulins was developed using a commercial polyclonal antiserum with reactivity towards epitopes on the light chains, which are not expressed when they are bound to heavy chains. The assay, on a centrifugal analyser, is simple and rapid. The limit of detection is 5 mg/l of free light chain, with an assay range of 5-120 mg/l, intrabatch precisions from 1.5-6.4%, and interbatch precisions from 6.5-8.9%. The assay was only slightly less sensitive than colloidal gold staining of cellulose acetate electrophoreses for the detection of Bence-Jones protein in urine. For the serial monitoring of response to chemotherapy in patients with myeloma, the assay correlated well with serum paraprotein estimates obtained by densitometric scanning of Ponceau stained cellulose acetate electrophoreses, but not with serum beta-2 microglobulin measurements, even after correction for the effects of creatinine. These assays may prove to be of use for the monitoring of tumour response in the treatment of Bence-Jones myeloma. PMID:1906071

Detection of the lunar body tide by the Lunar Orbiter Laser Altimeter.

PubMed

Mazarico, Erwan; Barker, Michael K; Neumann, Gregory A; Zuber, Maria T; Smith, David E

2014-04-16

The Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter spacecraft collected more than 5 billion measurements in the nominal 50 km orbit over ∼10,000 orbits. The data precision, geodetic accuracy, and spatial distribution enable two-dimensional crossovers to be used to infer relative radial position corrections between tracks to better than ∼1 m. We use nearly 500,000 altimetric crossovers to separate remaining high-frequency spacecraft trajectory errors from the periodic radial surface tidal deformation. The unusual sampling of the lunar body tide from polar lunar orbit limits the size of the typical differential signal expected at ground track intersections to ∼10 cm. Nevertheless, we reliably detect the topographic tidal signal and estimate the associated Love number h 2 to be 0.0371 ± 0.0033, which is consistent with but lower than recent results from lunar laser ranging. Altimetric data are used to create radial constraints on the tidal deformationThe body tide amplitude is estimated from the crossover dataThe estimated Love number is consistent with previous estimates but more precise.

Direct and precise determination of environmental radionuclides in solid materials using a modified Marinelli beaker and a HPGe detector.

PubMed

Seo, B K; Lee, K Y; Yoon, Y Y; Lee, D W

2001-06-01

A simple but precise detection method was studied for the determination of natural radionuclides using a conventional HPGe detector. A new aluminium beaker instead of a plastic Marinelli beaker was constructed and examined to reach radioactive equilibrium conditions between radon and its daughter elements without the escape of gaseous radon. Using this beaker fifteen natural radionuclides from three natural decay series could be determined by direct gamma-ray measurement and sixteen radionuclides could be determined indirectly after radioactive equilibrium had been reached. Analytical results from ground water were compared with those from conventional alpha spectroscopy and the results agreed well within 12% difference. Nitrogen gas purge was used to replace the surrounding air of the detector to obtain a stable background and reducing the interference of radon daughter nuclides in the atmosphere. The use of nitrogen purging and the aluminium Marinelli beaker results in an approximately tenfold increase of sensitivity and a decrease of the detection limit of 226Ra to about 0.74 Bq kg(-1) in soil samples.

RP-HPLC Method Development and Validation for Determination of Eptifibatide Acetate in Bulk Drug Substance and Pharmaceutical Dosage Forms.

PubMed

Bavand Savadkouhi, Maryam; Vahidi, Hossein; Ayatollahi, Abdul Majid; Hooshfar, Shirin; Kobarfard, Farzad

2017-01-01

A new, rapid, economical and isocratic reverse phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of eptifibatide acetate, a small synthetic antiplatelet peptide, in bulk drug substance and pharmaceutical dosage forms. The developed method was validated as per of ICH guidelines. The chromatographic separation was achieved isocratically on C18 column (150 x 4.60 mm i.d., 5 µM particle size) at ambient temperature using acetonitrile (ACN), water and trifluoroacetic acid (TFA) as mobile phase at flow rate of 1 mL/min and UV detection at 275 nm. Eptifibatide acetate exhibited linearity over the concentration range of 0.15-2 mg/mL (r 2 =0.997) with limit of detection of 0.15 mg/mL The accuracy of the method was 96.4-103.8%. The intra-day and inter-day precision were between 0.052% and 0.598%, respectively. The present successfully validated method with excellent selectivity, linearity, sensitivity, precision and accuracy was applicable for the assay of eptifibatide acetate in bulk drug substance and pharmaceutical dosage forms.

A CO trace gas detection system based on continuous wave DFB-QCL

NASA Astrophysics Data System (ADS)

Dang, Jingmin; Yu, Haiye; Sun, Yujing; Wang, Yiding

2017-05-01

A compact and mobile system was demonstrated for the detection of carbon monoxide (CO) at trace level. This system adopted a high-power, continuous wave (CW), distributed feedback quantum cascade laser (DFB-QCL) operating at ∼22 °C as excitation source. Wavelength modulation spectroscopy (WMS) as well as second harmonic detection was used to isolate complex, overlapping spectral absorption features typical of ambient pressures and to achieve excellent specificity and high detection sensitivity. For the selected P(11) absorption line of CO molecule, located at 2099.083 cm-1, a limit of detection (LoD) of 26 ppb by volume (ppbv) at atmospheric pressure was achieved with a 1 s acquisition time. Allan deviation analysis was performed to investigate the long term performance of the CO detection system, and a measurement precision of 3.4 ppbv was observed with an optimal integration time of approximate 114 s, which verified the reliable and robust operation of the developed system.

Validation of PCR methods for quantitation of genetically modified plants in food.

PubMed

Hübner, P; Waiblinger, H U; Pietsch, K; Brodmann, P

2001-01-01

For enforcement of the recently introduced labeling threshold for genetically modified organisms (GMOs) in food ingredients, quantitative detection methods such as quantitative competitive (QC-PCR) and real-time PCR are applied by official food control laboratories. The experiences of 3 European food control laboratories in validating such methods were compared to describe realistic performance characteristics of quantitative PCR detection methods. The limit of quantitation (LOQ) of GMO-specific, real-time PCR was experimentally determined to reach 30-50 target molecules, which is close to theoretical prediction. Starting PCR with 200 ng genomic plant DNA, the LOQ depends primarily on the genome size of the target plant and ranges from 0.02% for rice to 0.7% for wheat. The precision of quantitative PCR detection methods, expressed as relative standard deviation (RSD), varied from 10 to 30%. Using Bt176 corn containing test samples and applying Bt176 specific QC-PCR, mean values deviated from true values by -7to 18%, with an average of 2+/-10%. Ruggedness of real-time PCR detection methods was assessed in an interlaboratory study analyzing commercial, homogeneous food samples. Roundup Ready soybean DNA contents were determined in the range of 0.3 to 36%, relative to soybean DNA, with RSDs of about 25%. Taking the precision of quantitative PCR detection methods into account, suitable sample plans and sample sizes for GMO analysis are suggested. Because quantitative GMO detection methods measure GMO contents of samples in relation to reference material (calibrants), high priority must be given to international agreements and standardization on certified reference materials.

Design and analysis of a spectro-angular surface plasmon resonance biosensor operating in the visible spectrum

NASA Astrophysics Data System (ADS)

Filion-Côté, Sandrine; Roche, Philip J. R.; Foudeh, Amir M.; Tabrizian, Maryam; Kirk, Andrew G.

2014-09-01

Surface plasmon resonance (SPR) sensing is one of the most widely used methods to implement biosensing due to its sensitivity and capacity for label-free detection. Whilst most commercial SPR sensors operate in the angular regime, it has recently been shown that an increase in sensitivity and a greater robustness against noise can be achieved by measuring the reflectivity when varying both the angle and wavelength simultaneously, in a so-called spectro-angular SPR biosensor. A single value decomposition method is used to project the two-dimensional spectro-angular reflection signal onto a basis set and allow the image obtained from an unknown refractive index sample to be compared very accurately with a pre-calculated reference set. Herein we demonstrate that a previously reported system operated in the near infra-red has a lower detection limit when operating in the visible spectrum due to the improved spatial resolution and numerical precision of the image sensor. The SPR biosensor presented here has an experimental detection limit of 9.8 × 10-7 refractive index unit. To validate the system as a biosensor, we also performed the detection of synthetic RNA from pathogenic Legionella pneumophila with the developed biosensing platform.

Phytohormone profiling of the sweet orange (Citrus sinensis (L.) Osbeck) leaves and roots using GC-MS-based method.

PubMed

Nehela, Yasser; Hijaz, Faraj; Elzaawely, Abdelnaser A; El-Zahaby, Hassan M; Killiny, Nabil

2016-07-20

Phytohormones mainly affect plant development and trigger varied responses to biotic and abiotic stresses. The sensitivity of methods used to profile phytohormones is a vital factor that affects the results. We used an improved GC-MS-based method in the selective ion-monitoring (SIM) mode to study the phytohormone profiling in citrus tissues. One extraction solvent mixture and two derivatization reagents were used, methyl chloroformate (MCF) and N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA). The method showed a low limit of detection and low limit of quantification with high extraction recovery percentage and reproducibility. Overall, we detected 13 phytohormones belonging to six different groups. Auxins, SAs, tJA, and ABA were detected after derivatization with MCF while cytokinins and GAs were detected after derivatization with MSTFA. Cytokinins, SAs, and gibberellins were found in all tissues while auxins and tJA were observed only in the leaves. ABA was found in leaves and roots, but not in root tips. The method we used is efficient, precise, and appropriate to study citrus phytohormonal profiles to understand their crosstalk and responses to environmental and biological stresses. Copyright © 2016 Elsevier GmbH. All rights reserved.

Detection of beryllium in digested autopsy tissues by inductively coupled plasma mass spectrometry using a high matrix interface configuration.

PubMed

Larivière, Dominic; Tremblay, Mélodie; Durand-Jézéquel, Myriam; Tolmachev, Sergei

2012-04-01

This article describes a robust methodology using the combination of instrumental design (high matrix interface-HMI), sample dilution and internal standardization for the quantification of beryllium (Be) in various digested autopsy tissues using inductively coupled plasma mass spectrometry. The applicability of rhodium as a proper internal standard for Be was demonstrated in three types of biological matrices (i.e., femur, hair, lung tissues). Using HMI, it was possible to achieve instrumental detection limits and sensitivity of 0.6 ng L(-1) and 157 cps L ng(-1), respectively. Resilience to high salt matrices of the HMI setup was also highlighted using bone mimicking solution ([Ca(2+)] = 26 to 1,400 mg L(-1)), providing a 14-fold increase in tolerance and a 2.7-fold decrease in method detection limit compared to optimized experimental conditions obtained without the HMI configuration. Precision of the methodology to detect low levels of Be in autopsy samples was demonstrated using hair and blood certified reference materials. Be concentration ranging from 0.015 to 255 μg kg(-1) in autopsy samples obtained from the U.S. Transuranium and Uranium Registries were measured using the methodology presented.

Compatibility of a Diffractive Pupil and Coronagraphic Imaging

NASA Technical Reports Server (NTRS)

Bendek, Eduardo; Belikov, Rusian; Pluzhnyk, Yevgeniy; Guyon, Olivier

2013-01-01

Detection and characterization of exo-earths require direct-imaging techniques that can deliver contrast ratios of 10(exp 10) at 100 milliarc-seconds or smaller angular separation. At the same time, astrometric data is required to measure planet masses and can help detect planets and constrain their orbital parameters. To minimize costs, a single space mission can be designed using a high efficiency coronograph to perform direct imaging and a diffractive pupil to calibrate wide-field distortions to enable high precision astrometric measurements. This paper reports the testing of a diffractive pupil on the high-contrast test bed at the NASA Ames Research Center to assess the compatibility of using a diffractive pupil with coronographic imaging systems. No diffractive contamination was found within our detectability limit of 2x10(exp -7) contrast outside a region of 12lambda/D and 2.5x10(exp -6) within a region spanning from 2 to 12lambda/D. Morphology of the image features suggests that no contamination exists even beyond the detectability limit specified or at smaller working angles. In the case that diffractive contamination is found beyond these stated levels, active wavefront control would be able to mitigate its intensity to 10(exp -7) or better contrast.

One-pot synthesis of a multi-template molecularly imprinted polymer for the extraction of six sulfonamide residues from milk before high-performance liquid chromatography with diode array detection.

PubMed

Kechagia, Maria; Samanidou, Victoria; Kabir, Abuzar; Furton, Kenneth G

2018-02-01

A highly selective molecularly imprinted polymer sorbent was synthesized and employed for the simultaneous determination of six sulfonamide antibiotic residues (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, and sulfamethizole) in milk samples. Multi-analyte imprinted particles were used as a sorbent in solid-phase extraction. Sulfonamides were separated on a high-performance liquid chromatography column (Merck-Lichrospher RP18e, 5 μm 250 × 4 mm) and further identified and quantified by diode array detection. Several parameters including required loading of the molecularly imprinted polymer sorbent, mass of milk, volume, and type of elution solvent, as well as time for absorption and elution were investigated to obtain optimal experimental conditions. For comparison purpose, a non-imprinted polymer was applied under the optimum conditions. The validation study according to the European Union Decision 2002/657/EC was based on the investigation of linearity, selectivity, stability, limits of detection and quantitation, decision limit, detection capability, trueness, precision, and ruggedness according to Youden's approach. The decision limit and detection capability values in the milk were achieved from 101.9 to 113.5 μg/kg and from 114.4 to 135.4 μg/kg, respectively, depending on the target sulfonamide drug. Finally, the optimized protocol was successfully applied to commercial milk samples and human breast milk. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antidepressants detection and quantification in whole blood samples by GC-MS/MS, for forensic purposes.

PubMed

Truta, Liliana; Castro, André L; Tarelho, Sónia; Costa, Pedro; Sales, M Goreti F; Teixeira, Helena M

2016-09-05

Depression is among the most prevalent psychiatric disorders of our society, leading to an increase in antidepressant drug consumption that needs to be accurately determined in whole blood samples in Forensic Toxicology Laboratories. For this purpose, this work presents a new gas chromatography tandem mass spectrometry (GC-MS/MS) method targeting the simultaneous and rapid determination of 14 common Antidepressants in whole blood: 13 Antidepressants (amitriptyline, citalopram, clomipramine, dothiepin, fluoxetine, imipramine, mianserin, mirtazapine, nortryptiline, paroxetine, sertraline, trimipramine and venlafaxine) and 1 Metabolite (N-desmethylclomipramine). Solid-phase extraction was used prior to chromatographic separation. Chromatographic and MS/MS parameters were selected to improve sensitivity, peak resolution and unequivocal identification of the eluted analyte. The detection was performed on a triple quadrupole tandem MS in selected ion monitoring (SIM) mode in tandem, using electronic impact ionization. Clomipramine-D3 and trimipramine-D3 were used as deutered internal standards. The validation parameters included linearity, limits of detection, lower limit of quantification, selectivity/specificity, extraction efficiency, carry-over, precision and robustness, and followed internationally accepted guidelines. Limits of quantification and detection were lower than therapeutic and sub-therapeutic concentration ranges. Overall, the method offered good selectivity, robustness and quick response (<16min) for typical concentration ranges, both for therapeutic and lethal levels. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative aspects of microchip isotachophoresis for high precision determination of main components in pharmaceuticals.

PubMed

Hradski, Jasna; Chorváthová, Mária Drusková; Bodor, Róbert; Sabo, Martin; Matejčík, Štefan; Masár, Marián

2016-12-01

Although microchip electrophoresis (MCE) is intended to provide reliable quantitative data, so far there is only limited attention paid to these important aspects. This study gives a general overview of key aspects to be followed to reach high-precise determination using isotachophoresis (ITP) on the microchip with conductivity detection. From the application point of view, the procedure for the determination of acetate, a main component in the pharmaceutical preparation buserelin acetate, was developed. Our results document that run-to-run fluctuations in the sample injection volume limit the reproducibility of quantitation based on the external calibration. The use of a suitable internal standard (succinate in this study) improved the repeatability of the precision of acetate determination from six to eight times. The robustness of the procedure was studied in terms of impact of fluctuations in various experimental parameters (driving current, concentration of the leading ions, pH of the leading electrolyte and buffer impurities) on the precision of the ITP determination. The use of computer simulation programs provided means to assess the ITP experiments using well-defined theoretical models. A long-term validity of the calibration curves on two microchips and two MCE equipments was verified. This favors ITP over other microchip electrophoresis techniques, when chip-to-chip or equipment-to-equipment transfer of the analytical method is required. The recovery values in the range of 98-101 % indicate very accurate determination of acetate in buserelin acetate, which is used in the treatment of hormone-dependent tumors. This study showed that microchip ITP is suitable for reliable determination of main components in pharmaceutical preparations.

Detection And Mapping (DAM) package. Volume 4A: Software System Manual, part 1

NASA Technical Reports Server (NTRS)

Schlosser, E. H.

1980-01-01

The package is an integrated set of manual procedures, computer programs, and graphic devices designed for efficient production of precisely registered and formatted maps from digital LANDSAT multispectral scanner (MSS) data. The software can be readily implemented on any Univac 1100 series computer with standard peripheral equipment. This version of the software includes predefined spectral limits for use in classifying and mapping surface water for LANDSAT-1, LANDSAT-2, and LANDSAT-3. Tape formats supported include X, AM, and PM.

Commissioning Cornell OSTs for SRF cavity testing at Jlab

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

Eremeev, Grigory

2011-07-01

Understanding the current quench limitations in SRF cavities is a topic essential for any SRF accelerator that requires high fields. This understanding crucially depends on correct and precise quench identification. Second sound quench detection in superfluid liquid helium with oscillating superleak transducers is a technique recently applied at Cornell University as a fast and versatile method for quench identification in SRF cavities. Having adopted Cornell design, we report in this contribution on our experience with OST for quench identification in different cavities at JLab.

Validation of an In Vitro Bioaccessibility Test Method for Estimation of Bioavailability of Arsenic from Soil and Sediment

DTIC Science & Technology

2012-12-01

calibrated using a certified mineral or pure metal standard and counting times are chosen to provide 3-sigma detection limits of between 100-200 ppm...also submit “blind” duplicates for analyses. The precision of the data generated by the “EMPA point count ” will be evaluated by calculating RPD values...important to consider the variation in results among all samples studied for a particular media, since the overall particle count is very large. Data

Collection of quantitative chemical release field data.

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

Demirgian, J.; Macha, S.; Loyola Univ.

1999-01-01

Detection and quantitation of chemicals in the environment requires Fourier-transform infrared (FTIR) instruments that are properly calibrated and tested. This calibration and testing requires field testing using matrices that are representative of actual instrument use conditions. Three methods commonly used for developing calibration files and training sets in the field are a closed optical cell or chamber, a large-scale chemical release, and a small-scale chemical release. There is no best method. The advantages and limitations of each method should be considered in evaluating field results. Proper calibration characterizes the sensitivity of an instrument, its ability to detect a component inmore » different matrices, and the quantitative accuracy and precision of the results.« less

Normal and polar-organic-phase high-performance liquid chromatographic enantioresolution of omeprazole, rabeprazole, lansoprazole and pantoprazole using monochloro-methylated cellulose-based chiral stationary phase and determination of dexrabeprazole.

PubMed

Dixit, Shuchi; Dubey, Rituraj; Bhushan, Ravi

2014-01-01

Enantioresolution of four anti-ulcer drugs (chiral sulfoxides), namely, omeprazole, rabeprazole, lansoprazole and pantoprazole, was carried out by high-performance liquid chromatography using a polysaccharide-based chiral stationary phase consisting of monochloromethylated cellulose (Lux cellulose-2) under normal and polar-organic-phase conditions with ultraviolet detection at 285 nm. The method was validated for linearity, accuracy, precision, robustness and limit of detection. The optimized enantioresolution method was compared for both the elution modes. The optimized method was further utilized to check the enantiomeric purity of dexrabeprazole. Copyright © 2013 John Wiley & Sons, Ltd.

Simultaneous Proteomic Discovery and Targeted Monitoring using Liquid Chromatography, Ion Mobility Spectrometry, and Mass Spectrometry

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

Burnum-Johnson, Kristin E.; Nie, Song; Casey, Cameron P.

Current proteomics approaches are comprised of both broad discovery measurements as well as more quantitative targeted measurements. These two different measurement types are used to initially identify potentially important proteins (e.g., candidate biomarkers) and then enable improved quantification for a limited number of selected proteins. However, both approaches suffer from limitations, particularly the lower sensitivity, accuracy, and quantitation precision for discovery approaches compared to targeted approaches, and the limited proteome coverage provided by targeted approaches. Herein, we describe a new proteomics approach that allows both discovery and targeted monitoring (DTM) in a single analysis using liquid chromatography, ion mobility spectrometrymore » and mass spectrometry (LC-IMS-MS). In DTM, heavy labeled peptides for target ions are spiked into tryptic digests and both the labeled and unlabeled peptides are broadly detected using LC-IMS-MS instrumentation, allowing the benefits of discovery and targeted approaches. To understand the possible improvement of the DTM approach, it was compared to LC-MS broad measurements using an accurate mass and time tag database and selected reaction monitoring (SRM) targeted measurements. The DTM results yielded greater peptide/protein coverage and a significant improvement in the detection of lower abundance species compared to LC-MS discovery measurements. DTM was also observed to have similar detection limits as SRM for the targeted measurements indicating its potential for combining the discovery and targeted approaches.« less

Development a low-cost carbon monoxide sensor using homemade CW-DFB QCL and board-level electronics

NASA Astrophysics Data System (ADS)

Dang, Jingmin; Yu, Haiye; Zheng, Chuantao; Wang, Lijun; Sui, Yuanyuan; Wang, Yiding

2018-05-01

A mid-infrared sensor was demonstrated for the detection of carbon monoxide (CO) at trace level. In order to reduce cost, a homemade continuous-wave mode distributed feedback quantum cascade laser (CW-DFB QCL), a mini gas cell with 1.6-m optical length, and some self-development electronic modules were adopted as excitation source, absorption pool, and signal controlling and processing tool, respectively. Wavelength modulation spectroscopy (WMS) and phase sensitive detection (PSD) techniques as well as wavelet filtering software algorithm were used to reduce the influence of light source fluctuation and system noise and to improve measurement precision and sensitivity. Under the selected P(11) absorption line located at 2099.083 cm-1, a limit of detection (LoD) of 26 parts per billion by volume (ppbv) at atmospheric pressure was achieved with a 1-s acquisition time. Allan deviation was used to characterize the long-term performance of the CO sensor, and a measurement precision of ∼3.4 ppbv was observed with an optimal integration time of ∼114 s. As a field measurement, a continuous monitoring on indoor CO concentration for a period of 24 h was conducted, which verified the reliable and robust operation of the developed sensor.

Status of air-shower measurements with sparse radio arrays

NASA Astrophysics Data System (ADS)

Schröder, Frank G.

2017-03-01

This proceeding gives a summary of the current status and open questions of the radio technique for cosmic-ray air showers, assuming that the reader is already familiar with the principles. It includes recent results of selected experiments not present at this conference, e.g., LOPES and TREND. Current radio arrays like AERA or Tunka-Rex have demonstrated that areas of several km2 can be instrumented for reasonable costs with antenna spacings of the order of 200m. For the energy of the primary particle such sparse antenna arrays can already compete in absolute accuracy with other precise techniques, like the detection of air-fluorescence or air-Cherenkov light. With further improvements in the antenna calibration, the radio detection might become even more accurate. For the atmospheric depth of the shower maximum, Xmax, currently only the dense array LOFAR features a precision similar to the fluorescence technique, but analysis methods for the radio measurement of Xmax are still under development. Moreover, the combination of radio and muon measurements is expected to increase the accuracy of the mass composition, and this around-the-clock recording is not limited to clear nights as are the light-detection methods. Consequently, radio antennas will be a valuable add-on for any air shower array targeting the energy range above 100 PeV.

Editorial

NASA Astrophysics Data System (ADS)

Buitink, S.; Hörandel, J. R.; de Jong, S.; Lahmann, R.; Nahnhauer, R.; Scholten, O.

2017-03-01

This proceeding gives a summary of the current status and open questions of the radio technique for cosmic-ray air showers, assuming that the reader is already familiar with the principles. It includes recent results of selected experiments not present at this conference, e.g., LOPES and TREND. Current radio arrays like AERA or Tunka-Rex have demonstrated that areas of several km2 can be instrumented for reasonable costs with antenna spacings of the order of 200m. For the energy of the primary particle such sparse antenna arrays can already compete in absolute accuracy with other precise techniques, like the detection of air-fluorescence or air-Cherenkov light. With further improvements in the antenna calibration, the radio detection might become even more accurate. For the atmospheric depth of the shower maximum, Xmax, currently only the dense array LOFAR features a precision similar to the fluorescence technique, but analysis methods for the radio measurement of Xmax are still under development. Moreover, the combination of radio and muon measurements is expected to increase the accuracy of the mass composition, and this around-the-clock recording is not limited to clear nights as are the light-detection methods. Consequently, radio antennas will be a valuable add-on for any air shower array targeting the energy range above 100 PeV.

Satellite Test of the Equivalence Principle as a Probe of Modified Newtonian Dynamics.

PubMed

Pereira, Jonas P; Overduin, James M; Poyneer, Alexander J

2016-08-12

The proposed satellite test of the equivalence principle (STEP) will detect possible violations of the weak equivalence principle by measuring relative accelerations between test masses of different composition with a precision of one part in 10^{18}. A serendipitous by-product of the experimental design is that the absolute or common-mode acceleration of the test masses is also measured to high precision as they oscillate along a common axis under the influence of restoring forces produced by the position sensor currents, which in drag-free mode lead to Newtonian accelerations as small as 10^{-14}  g. This is deep inside the low-acceleration regime where modified Newtonian dynamics (MOND) diverges strongly from the Newtonian limit of general relativity. We show that MOND theories (including those based on the widely used "n family" of interpolating functions as well as the covariant tensor-vector-scalar formulation) predict an easily detectable increase in the frequency of oscillations of the STEP test masses if the strong equivalence principle holds. If it does not hold, MOND predicts a cumulative increase in oscillation amplitude which is also detectable. STEP thus provides a new and potentially decisive test of Newton's law of inertia, as well as the equivalence principle in both its strong and weak forms.

Development and validation of a whole-exome sequencing test for simultaneous detection of point mutations, indels and copy-number alterations for precision cancer care

PubMed Central

Rennert, Hanna; Eng, Kenneth; Zhang, Tuo; Tan, Adrian; Xiang, Jenny; Romanel, Alessandro; Kim, Robert; Tam, Wayne; Liu, Yen-Chun; Bhinder, Bhavneet; Cyrta, Joanna; Beltran, Himisha; Robinson, Brian; Mosquera, Juan Miguel; Fernandes, Helen; Demichelis, Francesca; Sboner, Andrea; Kluk, Michael; Rubin, Mark A; Elemento, Olivier

2016-01-01

We describe Exome Cancer Test v1.0 (EXaCT-1), the first New York State-Department of Health-approved whole-exome sequencing (WES)-based test for precision cancer care. EXaCT-1 uses HaloPlex (Agilent) target enrichment followed by next-generation sequencing (Illumina) of tumour and matched constitutional control DNA. We present a detailed clinical development and validation pipeline suitable for simultaneous detection of somatic point/indel mutations and copy-number alterations (CNAs). A computational framework for data analysis, reporting and sign-out is also presented. For the validation, we tested EXaCT-1 on 57 tumours covering five distinct clinically relevant mutations. Results demonstrated elevated and uniform coverage compatible with clinical testing as well as complete concordance in variant quality metrics between formalin-fixed paraffin embedded and fresh-frozen tumours. Extensive sensitivity studies identified limits of detection threshold for point/indel mutations and CNAs. Prospective analysis of 337 cancer cases revealed mutations in clinically relevant genes in 82% of tumours, demonstrating that EXaCT-1 is an accurate and sensitive method for identifying actionable mutations, with reasonable costs and time, greatly expanding its utility for advanced cancer care. PMID:28781886

Policy implications of using a household consumption and expenditures survey versus an observed-weighed food record survey to design a food fortification program.

PubMed

Lividini, Keith; Fiedler, John L; Bermudez, Odilia I

2013-12-01

Observed-Weighed Food Record Surveys (OWFR) are regarded as the most precise dietary assessment methodology, despite their recognized shortcomings, which include limited availability, high cost, small samples with uncertain external validity that rarely include all household members, Hawthorne effects, and using only 1 or 2 days to identify "usual intake." Although Household Consumption and Expenditures Surveys (HCES) also have significant limitations, they are increasingly being used to inform nutrition policy To investigate differences in fortification simulations based on OWFR and HCES from Bangladesh. The pre- and postfortification nutrient intake levels from the two surveys were compared. The total population-based rank orderings of oil, wheat flour, and sugar coverage were identical for the two surveys. OWFR found differences in women's and children's coverage rates and average quantities consumed for all three foods that were not detected by HCES. Guided by the Food Fortification Formulator, we found that these differences did not result in differences in recommended fortification levels. Differences were found, however, in estimated impacts: although both surveys found that oil would be effective in reducing the prevalence of inadequate vitamin A intake among both subpopulations, only OWFR also found that sugar and wheat flour fortification would significantly reduce inadequate vitamin A intake among children. Despite the less precise measure of food consumption from HCES, the two surveys provide similar guidance for designing a fortification program. The external validity of these findings is limited. With relatively minor modifications, the precision of HCES in dietary assessment and the use ofHCES in fortification programming could be strengthened.

Simultaneous determination of flavonoids, isochlorogenic acids and triterpenoids in Ilex hainanensis Using high performance liquid chromatography coupled with diode array and evaporative light scattering detection.

PubMed

Peng, Bo; Qiao, Chun-Feng; Zhao, Jing; Huang, Wei-Hua; Hu, De-Jun; Liu, Hua-Gang; Li, Shao-Ping

2013-03-04

A high performance liquid chromatography coupled with diode array and evaporative light scattering detection (HPLC-DAD-ELSD) method for simultaneous determination of eight major bioactive compounds including two flavonoids (rutin and eriodictyol-7-O-β-D-glucopyranoside), two isochlorogenic acids (isochlorogenic acid A and isochlorogenic acid C) and four triterpenoids (ilexhainanoside D, ilexsaponin A1, ilexgenin A and ursolic acid) in Ilex hainanensis has been developed for the first time. The 283 nm wavelength was chosen for determination of two flavonoids and two isochlorogenic acids. ELSD was applied to determine four triterpenoids. The analysis was performed on an Agilent Zorbax SB-C18 column (250 × 4.6 mm i.d., 5 µm) with gradient elution of 0.2% formic acid in water and acetonitrile. The method was validated for linearity, limit of detection, limit of quantification, precision, repeatability and accuracy. The proposed method has been successfully applied for simultaneous quantification of the analytes in four samples of Ilex hainanensis, which is helpful for quality control of this plant.

Development and validation of an universal interface for compound-specific stable isotope analysis of chlorine (37Cl/35Cl) by GC-high-temperature conversion (HTC)-MS/IRMS.

PubMed

Renpenning, Julian; Hitzfeld, Kristina L; Gilevska, Tetyana; Nijenhuis, Ivonne; Gehre, Matthias; Richnow, Hans-Hermann

2015-03-03

A universal application of compound-specific isotope analysis of chlorine was thus far limited by the availability of suitable analysis techniques. In this study, gas chromatography in combination with a high-temperature conversion interface (GC-HTC), converting organic chlorine in the presence of H2 to gaseous HCl, was coupled to a dual-detection system, combining an ion trap mass spectrometer (MS) and isotope-ratio mass spectrometer (IRMS). The combination of the MS/IRMS detection enabled a detailed characterization, optimization, and online monitoring of the high-temperature conversion process via ion trap MS as well as a simultaneous chlorine isotope analysis by the IRMS. Using GC-HTC-MS/IRMS, chlorine isotope analysis at optimized conversion conditions resulted in very accurate isotope values (δ(37)Cl(SMOC)) for measured reference material with known isotope composition, including chlorinated ethylene, chloromethane, hexachlorocyclohexane, and trichloroacetic acids methyl ester. Respective detection limits were determined to be <15 nmol Cl on column with achieved precision of <0.3‰.

Dark field imaging system for size characterization of magnetic micromarkers

NASA Astrophysics Data System (ADS)

Malec, A.; Haiden, C.; Kokkinis, G.; Keplinger, F.; Giouroudi, I.

2017-05-01

In this paper we demonstrate a dark field video imaging system for the detection and size characterization of individual magnetic micromarkers suspended in liquid and the detection of pathogens utilizing magnetically labelled E.coli. The system follows dynamic processes and interactions of moving micro/nano objects close to or below the optical resolution limit, and is especially suitable for small sample volumes ( 10 μl). The developed detection method can be used to obtain clinical information about liquid contents when an additional biological protocol is provided, i.e., binding of microorganisms (e.g. E.coli) to specific magnetic markers. Some of the major advantages of our method are the increased sizing precision in the micro- and nano-range as well as the setup's simplicity making it a perfect candidate for miniaturized devices. Measurements can thus be carried out in a quick, inexpensive, and compact manner. A minor limitation is that the concentration range of micromarkers in a liquid sample needs to be adjusted in such a manner that the number of individual particles in the microscope's field of view is sufficient.

Multiresidue chromatographic method for the determination of macrolide residues in muscle by high-performance liquid chromatography with UV detection.

PubMed

Juhel-Gaugain, M; Anger, B; Laurentie, M

1999-01-01

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of tilmicosin, tylosin, spiramycin, and its major metabolite neospiramycin was developed that is suitable for porcine, bovine, and poultry muscles. Macrolide residues were extracted from muscle with acetonitrile, fat was removed by liquid-liquid extraction with isooctane, and the extract was then cleaned on Bond Elut C18 cartridges. The HPLC separation was performed on an Inertsil ODS3 C18 column (150 x 4 mm) with 0.05% trifluoroacetic acid-acetonitrile in a gradient mode. Two different chromatographic gradients were used for tilmicosin-tylosin and spiramycin-neospiramycin, and the detection wavelengths were 287 and 232 nm, respectively. The method was validated from 1/2 the maximum residue limit (MRL) to 4 times the MRL with pork muscle samples. Mean recoveries were 60, 63.5, 51, and 42% for tilmicosin, tylosin, spiramycin, and neospiramycin, respectively. The detection limits are 15 micrograms/kg for tilmicosin and tylosin, 30 micrograms/kg for spiramycin, and 25 micrograms/kg for neospiramycin. Linearity, precision, and accuracy of the method were also tested.

A search for methane in the atmosphere of Mars using ground-based mid infrared heterodyne spectroscopy

NASA Astrophysics Data System (ADS)

Sonnabend, G.; Stupar, D.; Sornig, M.; Stangier, T.; Kostiuk, T.; Livengood, T. A.

2013-09-01

We report our search for methane in the atmosphere of Mars using high-spectral resolution heterodyne spectroscopy in the 7.8 μm wavelength region. Resolving power and frequency precision of >106 of the technique enable identification and full resolution of a targeted spectral line in the terrestrial-Mars spectrum observed from the ground. Observations were carried out on two occasions, in April 2010 and May 2012 at the McMath-Pierce Solar Telescope and the NASA Infrared Telescope Facility, respectively. A single line in the ν4 band of methane at 1282.62448 cm-1 was targeted in both cases. No absorption due to methane was detected and only upper limits of ∼100 ppb for the martian atmospheric methane concentration were retrieved. Lack of observing time (due to weather) and telluric opacity greater than anticipated led to reduced signal-to-noise ratios (SNR). Based on current measurements and calculations, under proper viewing conditions, we estimate an achievable detection limit of ∼10 ppb using the infrared heterodyne technique - adequate for confirming reported detections of methane based on other techniques.

Chromatography related performance of the Monitor for AeRosols and GAses in ambient air (MARGA): laboratory and field-based evaluation

NASA Astrophysics Data System (ADS)

Chen, Xi; Walker, John T.; Geron, Chris

2017-10-01

Evaluation of the semi-continuous Monitor for AeRosols and GAses in ambient air (MARGA, Metrohm Applikon B.V.) was conducted with an emphasis on examination of accuracy and precision associated with processing of chromatograms. Using laboratory standards and atmospheric measurements, analytical accuracy, precision and method detection limits derived using the commercial MARGA software were compared to an alternative chromatography procedure consisting of a custom Java script to reformat raw MARGA conductivity data and Chromeleon (Thermo Scientific Dionex) software for peak integration. Our analysis revealed issues with accuracy and precision resulting from misidentification and misintegration of chromatograph peaks by the MARGA automated software as well as a systematic bias at low concentrations for anions. Reprocessing and calibration of raw MARGA data using the alternative chromatography method lowered method detection limits and reduced variability (precision) between parallel sampler boxes. Instrument performance was further evaluated during a 1-month intensive field campaign in the fall of 2014, including analysis of diurnal patterns of gaseous and particulate water-soluble species (NH3, SO2, HNO3, NH4+, SO42- and NO3-), gas-to-particle partitioning and particle neutralization state. At ambient concentrations below ˜ 1 µg m-3, concentrations determined using the MARGA software are biased +30 and +10 % for NO3- and SO42-, respectively, compared to concentrations determined using the alternative chromatography procedure. Differences between the two methods increase at lower concentrations. We demonstrate that positively biased NO3- and SO42- measurements result in overestimation of aerosol acidity and introduce nontrivial errors to ion balances of inorganic aerosol. Though the source of the bias is uncertain, it is not corrected by the MARGA online single-point internal LiBr standard. Our results show that calibration and verification of instrument accuracy by multilevel external standards is required to adequately control analytical accuracy. During the field intensive, the MARGA was able to capture rapid compositional changes in PM2.5 due to changes in meteorology and air mass history relative to known source regions of PM precursors, including a fine NO3- aerosol event associated with intrusion of Arctic air into the southeastern US.

GNSS Monitoring of Deformation within heavy civil infrastructure

NASA Astrophysics Data System (ADS)

Montillet, Jean-Philippe; Melbourne, Timothy; Szeliga, Walter; Schrock, Gavin

2015-04-01

The steady increase in precision simultaneous with the decreasing of continuous GPS monitoring has enabled the deployment of receivers for a host of new activities. Here we discuss the precision obtained from several multi-station installations operated over a five-year period on several heavy civil-engineered structures, including two earthen-fill dams and subsiding highway overpass damaged by seismic shaking. In the past 5 years, the Cascadia Hazards Institute (Pacific Northwest Geodetic Array) at Central Washington University together with the Washington department of public utilities (Land Survey) have been monitoring several structures around Seattle area including two dams (Howard Hansen and Tolt). One aim of this study is to test the use of continuous GNSS in order to detect any deformations due to rapid pool level rises or to monitor the safety of a structure when an Earthquake strikes it. In this study, data is processed using Real Time Kinematic GPS with short baseline (d < 500 m) and GPS daily position (PPP). However, multipath is the most limiting factor on accuracy for very precise positioning applications with GPS. It is very often present indoors and outdoors, especially in narrow valleys with a limited view of the sky. As a result, multipath can amount to an error of a few centimetres. Unfortunately, the accuracy requirements of precision deformation monitoring are generally at the sub centimetre level, which is presently a big challenge on an epoch-by-epoch basis with regular, carrier phase techniques. Thus, it needs to be properly mitigated. In this study, several stations are set up on the dams (4 stations on the Tolt reservoir and 10 stations on the Howard Hansen dam), and spatial filtering can then be used to mitigate multipath. In addition, several signal processing techniques are also investigated (i.e. Empirical mode decomposition, sidereal filtering, adaptive filtering). RTK GPS should allow to monitor rapid deformations, whereas GPS daily position is used to detect long-term deformations such as the pool level rises due to the melting of ice cap on surrounding mountains. Note that RTK measurements are processed with the MIT software TRACK and the GPS daily positions estimated with GAMIT-GLOBK.

Dissociations of the number and precision of visual short-term memory representations in change detection.

PubMed

Xie, Weizhen; Zhang, Weiwei

2017-11-01

The present study dissociated the number (i.e., quantity) and precision (i.e., quality) of visual short-term memory (STM) representations in change detection using receiver operating characteristic (ROC) and experimental manipulations. Across three experiments, participants performed both recognition and recall tests of visual STM using the change-detection task and the continuous color-wheel recall task, respectively. Experiment 1 demonstrated that the estimates of the number and precision of visual STM representations based on the ROC model of change-detection performance were robustly correlated with the corresponding estimates based on the mixture model of continuous-recall performance. Experiments 2 and 3 showed that the experimental manipulation of mnemonic precision using white-noise masking and the experimental manipulation of the number of encoded STM representations using consolidation masking produced selective effects on the corresponding measures of mnemonic precision and the number of encoded STM representations, respectively, in both change-detection and continuous-recall tasks. Altogether, using the individual-differences (Experiment 1) and experimental dissociation (Experiment 2 and 3) approaches, the present study demonstrated the some-or-none nature of visual STM representations across recall and recognition.

Detecting trihalomethanes using nanoporous-carbon coated surface-acoustic-wave sensors

DOE PAGES

Siegal, Michael P.; Mowry, Curtis D.; Pfeifer, Kent B.; ...

2015-03-07

We study nanoporous-carbon (NPC) grown via pulsed laser deposition (PLD) as a sorbent coating on 96.5-MHz surface-acoustic-wave (SAW) devices to detect trihalomethanes (THMs), regulated byproducts from the chemical treatment of drinking water. Using both insertion-loss and isothermal-response measurements from known quantities of chloroform, the highest vapor pressure THM, we optimize the NPC mass-density at 1.05 ± 0.08 g/cm3 by controlling the background argon pressure during PLD. Precise THM quantities in a chlorobenzene solvent are directly injected into a separation column and detected as the phase-angle shift of the SAW device output compared to the drive signal. Using optimized NPC-coated SAWs,more » we study the chloroform response as a function of operating temperatures ranging from 10–50°C. Finally, we demonstrate individual responses from complex mixtures of all four THMs, with masses ranging from 10–2000 ng, after gas chromatography separation. As a result, estimates for each THM detection limit using a simple peak-height response evaluation are 4.4 ng for chloroform and 1 ng for bromoform; using an integrated-peak area response analysis improves the detection limits to 0.73 ng for chloroform and 0.003 ng bromoform.« less

Validation of a high-performance liquid chromatographic method with UV detection for the determination of ethopabate residues in poultry liver.

PubMed

Granja, Rodrigo H M M; Niño, Alfredo M Montes; Zucchetti, Roberto A M; Niño, Rosario E Montes; Salerno, Alessandro G

2008-01-01

Ethopabate is frequently used in the prophylaxis and treatment of coccidiosis in poultry. Residues of this drug in food present a potential risk to consumers. A simple, rapid, and sensitive column high-performance liquid chromatographic (HPLC) method with UV detection for determination of ethopabate in poultry liver is presented. The drug is extracted with acetonitrile. After evaporation, the residue is dissolved with an acetone-hexane mixture and cleaned up by solid-phase extraction using Florisil columns. The analyte is then eluted with methanol. LC analysis is carried out on a C18 5 microm Gemini column, 15 cm x 4.6 mm. Ethopabate is quantified by means of UV detection at 270 nm. Parameters such as decision limit, detection capability, precision, recovery, ruggedness, and measurement uncertainty were calculated according to method validation guidelines provided in 2002/657/EC and ISO/IEC 17025:2005. Decision limit and detection capability were determined to be 2 and 3 microg/kg, respectively. Average recoveries from poultry samples fortified with 10, 15, and 20 microg/kg levels of ethopabate were 100-105%. A complete statistical analysis was performed on the results obtained, including an estimation of the method uncertainty. The method is to be implemented into Brazil's residue monitoring and control program for ethopabate.

A Review of Flow Analysis Methods for Determination of Radionuclides in Nuclear Wastes and Nuclear Reactor Coolants

DOE PAGES

Trojanowicz, Marek; Kolacinska, Kamila; Grate, Jay W.

2018-02-13

Here, the safety and security of nuclear power plant operations depend on the application of the most appropriate techniques and methods of chemical analysis, where modern flow analysis methods prevail. Nevertheless, the current status of the development of these methods is more limited than it might be expected based on their genuine advantages. The main aim of this paper is to review the automated flow analysis procedures developed with various detection methods for the nuclear energy industry. The flow analysis methods for the determination of radionuclides, that have been reported to date, are primarily focused on their environmental applications. Themore » benefits of the application of flow methods in both monitoring of the nuclear wastes and process analysis of the primary circuit coolants of light water nuclear reactors will also be discussed. The application of either continuous flow methods (CFA) or injection methods (FIA, SIA) of the flow analysis with the β–radiometric detection shortens the analysis time and improves the precision of determination due to mechanization of certain time-consuming operations of the sample processing. Compared to the radiometric detection, the mass spectrometry (MS) detection enables one to perform multicomponent analyses as well as the determination of transuranic isotopes with much better limits of detection.« less

A Review of Flow Analysis Methods for Determination of Radionuclides in Nuclear Wastes and Nuclear Reactor Coolants

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

Trojanowicz, Marek; Kolacinska, Kamila; Grate, Jay W.

Here, the safety and security of nuclear power plant operations depend on the application of the most appropriate techniques and methods of chemical analysis, where modern flow analysis methods prevail. Nevertheless, the current status of the development of these methods is more limited than it might be expected based on their genuine advantages. The main aim of this paper is to review the automated flow analysis procedures developed with various detection methods for the nuclear energy industry. The flow analysis methods for the determination of radionuclides, that have been reported to date, are primarily focused on their environmental applications. Themore » benefits of the application of flow methods in both monitoring of the nuclear wastes and process analysis of the primary circuit coolants of light water nuclear reactors will also be discussed. The application of either continuous flow methods (CFA) or injection methods (FIA, SIA) of the flow analysis with the β–radiometric detection shortens the analysis time and improves the precision of determination due to mechanization of certain time-consuming operations of the sample processing. Compared to the radiometric detection, the mass spectrometry (MS) detection enables one to perform multicomponent analyses as well as the determination of transuranic isotopes with much better limits of detection.« less

Simultaneous analysis of six aldehyde-DNA adducts in salivary DNA of nonsmokers and smokers using stable isotope dilution liquid chromatography electrospray ionization-tandem mass spectrometry.

PubMed

Li, Xiangyu; Liu, Lujuan; Wang, Hongjuan; Chen, Jian; Zhu, Beibei; Chen, Huan; Hou, Hongwei; Hu, Qingyuan

2017-08-15

A stable method, using isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS), to simultaneously determine six aldehyde-DNA adducts was developed and applied to the analysis of human salivary DNA samples. The detection limit of these six DNA adducts was in the range of 0.006-0.014ng/mL and that of the quantification limit was 0.017-0.026ng/mL. The intra-day and inter-day precision of all aldehyde-DNA adducts was <10%. The analysis was completed within 25min. Additionally, a noninvasive technique was used to collect the DNA samples from human saliva. The new method was successfully applied for the analysis of salivary DNA of nonsmokers and smokers. Five aldehyde-DNA adducts were detected in both smoker and nonsmoker salivary DNA, while α-Acr-dG was not detected in all the samples. Among these detected DNA adducts, no significant differences were found between smoker and nonsmoker (p>0.05). This may due to the individual detoxifying differences or environmental and endogenous exposure. Our study provides a rapid and selective method to simultaneously detect six aldehyde-DNA adducts and to assess potential DNA damage induced by aldehydes. Copyright © 2017 Elsevier B.V. All rights reserved.

Near-infrared spectroscopy for the detection and quantification of bacterial contaminations in pharmaceutical products.

PubMed

Quintelas, Cristina; Mesquita, Daniela P; Lopes, João A; Ferreira, Eugénio C; Sousa, Clara

2015-08-15

Accurate detection and quantification of microbiological contaminations remains an issue mainly due the lack of rapid and precise analytical techniques. Standard methods are expensive and time-consuming being associated to high economic losses and public health threats. In the context of pharmaceutical industry, the development of fast analytical techniques able to overcome these limitations is crucial and spectroscopic techniques might constitute a reliable alternative. In this work we proved the ability of Fourier transform near infrared spectroscopy (FT-NIRS) to detect and quantify bacteria (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens, Salmonella enterica, Staphylococcus epidermidis) from 10 to 10(8) CFUs/mL in sterile saline solutions (NaCl 0.9%). Partial least squares discriminant analysis (PLSDA) models showed that FT-NIRS was able to discriminate between sterile and contaminated solutions for all bacteria as well as to identify the contaminant bacteria. Partial least squares (PLS) models allowed bacterial quantification with limits of detection ranging from 5.1 to 9 CFU/mL for E. coli and B. subtilis, respectively. This methodology was successfully validated in three pharmaceutical preparations (contact lens solution, cough syrup and topic anti-inflammatory solution) proving that this technique possess a high potential to be routinely used for the detection and quantification of bacterial contaminations. Copyright © 2015 Elsevier B.V. All rights reserved.

A review of flow analysis methods for determination of radionuclides in nuclear wastes and nuclear reactor coolants.

PubMed

Trojanowicz, Marek; Kołacińska, Kamila; Grate, Jay W

2018-06-01

The safety and security of nuclear power plant operations depend on the application of the most appropriate techniques and methods of chemical analysis, where modern flow analysis methods prevail. Nevertheless, the current status of the development of these methods is more limited than it might be expected based on their genuine advantages. The main aim of this paper is to review the automated flow analysis procedures developed with various detection methods for the nuclear energy industry. The flow analysis methods for the determination of radionuclides, that have been reported to date, are primarily focused on their environmental applications. The benefits of the application of flow methods in both monitoring of the nuclear wastes and process analysis of the primary circuit coolants of light water nuclear reactors will also be discussed. The application of either continuous flow methods (CFA) or injection methods (FIA, SIA) of the flow analysis with the β-radiometric detection shortens the analysis time and improves the precision of determination due to mechanization of certain time-consuming operations of the sample processing. Compared to the radiometric detection, the mass spectrometry (MS) detection enables one to perform multicomponent analyses as well as the determination of transuranic isotopes with much better limits of detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Achieving quantum precision limit in adaptive qubit state tomography

NASA Astrophysics Data System (ADS)

Hou, Zhibo; Zhu, Huangjun; Xiang, Guo-Yong; Li, Chuan-Feng; Guo, Guang-Can

2016-02-01

The precision limit in quantum state tomography is of great interest not only to practical applications but also to foundational studies. However, little is known about this subject in the multiparameter setting even theoretically due to the subtle information trade-off among incompatible observables. In the case of a qubit, the theoretic precision limit was determined by Hayashi as well as Gill and Massar, but attaining the precision limit in experiments has remained a challenging task. Here we report the first experiment that achieves this precision limit in adaptive quantum state tomography on optical polarisation qubits. The two-step adaptive strategy used in our experiment is very easy to implement in practice. Yet it is surprisingly powerful in optimising most figures of merit of practical interest. Our study may have significant implications for multiparameter quantum estimation problems, such as quantum metrology. Meanwhile, it may promote our understanding about the complementarity principle and uncertainty relations from the information theoretic perspective.

Validation of HPLC and UV spectrophotometric methods for the determination of meropenem in pharmaceutical dosage form.

PubMed

Mendez, Andreas S L; Steppe, Martin; Schapoval, Elfrides E S

2003-12-04

A high-performance liquid chromatographic method and a UV spectrophotometric method for the quantitative determination of meropenem, a highly active carbapenem antibiotic, in powder for injection were developed in present work. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. Chromatography was carried out by reversed-phase technique on an RP-18 column with a mobile phase composed of 30 mM monobasic phosphate buffer and acetonitrile (90:10; v/v), adjusted to pH 3.0 with orthophosphoric acid. The UV spectrophotometric method was performed at 298 nm. The samples were prepared in water and the stability of meropenem in aqueous solution at 4 and 25 degrees C was studied. The results were satisfactory with good stability after 24 h at 4 degrees C. Statistical analysis by Student's t-test showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and can be used for the reliable quantitation of meropenem in pharmaceutical dosage form.

Towards collaboration between unmanned aerial and ground vehicles for precision agriculture

NASA Astrophysics Data System (ADS)

Bhandari, Subodh; Raheja, Amar; Green, Robert L.; Do, Dat

2017-05-01

This paper presents the work being conducted at Cal Poly Pomona on the collaboration between unmanned aerial and ground vehicles for precision agriculture. The unmanned aerial vehicles (UAVs), equipped with multispectral/hyperspectral cameras and RGB cameras, take images of the crops while flying autonomously. The images are post processed or can be processed onboard. The processed images are used in the detection of unhealthy plants. Aerial data can be used by the UAVs and unmanned ground vehicles (UGVs) for various purposes including care of crops, harvest estimation, etc. The images can also be useful for optimized harvesting by isolating low yielding plants. These vehicles can be operated autonomously with limited or no human intervention, thereby reducing cost and limiting human exposure to agricultural chemicals. The paper discuss the autonomous UAV and UGV platforms used for the research, sensor integration, and experimental testing. Methods for ground truthing the results obtained from the UAVs will be used. The paper will also discuss equipping the UGV with a robotic arm for removing the unhealthy plants and/or weeds.

The design of photoelectric signal processing system for a nuclear magnetic resonance gyroscope based on FPGA

NASA Astrophysics Data System (ADS)

Zhang, Xian; Zhou, Binquan; Li, Hong; Zhao, Xinghua; Mu, Weiwei; Wu, Wenfeng

2017-10-01

Navigation technology is crucial to the national defense and military, which can realize the measurement of orientation, positioning, attitude and speed for moving object. Inertial navigation is not only autonomous, real-time, continuous, hidden, undisturbed but also no time-limited and environment-limited. The gyroscope is the core component of the inertial navigation system, whose precision and size are the bottleneck of the performance. However, nuclear magnetic resonance gyroscope is characteristic of the advantage of high precision and small size. Nuclear magnetic resonance gyroscope can meet the urgent needs of high-tech weapons and equipment development of new generation. This paper mainly designs a set of photoelectric signal processing system for nuclear magnetic resonance gyroscope based on FPGA, which process and control the information of detecting laser .The photoelectric signal with high frequency carrier is demodulated by in-phase and quadrature demodulation method. Finally, the processing system of photoelectric signal can compensate the residual magnetism of the shielding barrel and provide the information of nuclear magnetic resonance gyroscope angular velocity.

Multifamily determination of pesticide residues in soya-based nutraceutical products by GC/MS-MS.

PubMed

Páleníková, Agneša; Martínez-Domínguez, Gerardo; Arrebola, Francisco Javier; Romero-González, Roberto; Hrouzková, Svetlana; Frenich, Antonia Garrido

2015-04-15

An analytical method based on a modified QuEChERS extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was evaluated for the determination of 177 pesticides in soya-based nutraceutical products. The QuEChERS method was optimised and different extraction solvents and clean-up approaches were tested, obtaining the most efficient conditions with a mixture of sorbents (PSA, C18, GBC and Zr-Sep(+)). Recoveries were evaluated at 10, 50 and 100 μg/kg and ranged between 70% and 120%. Precision was expressed as relative standard deviation (RSD), and it was evaluated for more than 160 pesticides as intra and inter-day precision, with values always below 20% and 25%, respectively. Limits of detection (LODs) ranged from 0.1 to 10 μg/kg, whereas limits of quantification (LOQs) from 0.5 to 20 μg/kg. The applicability of the method was proved by analysing soya-based nutraceuticals. Two pesticides were found in these samples, malathion and pyriproxyfen, at 11.1 and 1.5 μg/kg respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Automated GC-MS analysis of free amino acids in biological fluids.

PubMed

Kaspar, Hannelore; Dettmer, Katja; Gronwald, Wolfram; Oefner, Peter J

2008-07-15

A gas chromatography-mass spectrometry (GC-MS) method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate is carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acids, thereby allowing automation of the entire procedure, including addition of reagents, extraction and injection into the GC-MS. The total analysis time was 30 min and 30 amino acids could be reliably quantified using 19 stable isotope-labeled amino acids as internal standards. Limits of detection (LOD) and lower limits of quantification (LLOQ) were in the range of 0.03-12 microM and 0.3-30 microM, respectively. The method was validated using a certified amino acid standard and reference plasma, and its applicability to different biological fluids was shown. Intra-day precision for the analysis of human urine, blood plasma, and cell culture medium was 2.0-8.8%, 0.9-8.3%, and 2.0-14.3%, respectively, while the inter-day precision for human urine was 1.5-14.1%.

Integrating biology, field logistics, and simulations to optimize parameter estimation for imperiled species

USGS Publications Warehouse

Lanier, Wendy E.; Bailey, Larissa L.; Muths, Erin L.

2016-01-01

Conservation of imperiled species often requires knowledge of vital rates and population dynamics. However, these can be difficult to estimate for rare species and small populations. This problem is further exacerbated when individuals are not available for detection during some surveys due to limited access, delaying surveys and creating mismatches between the breeding behavior and survey timing. Here we use simulations to explore the impacts of this issue using four hypothetical boreal toad (Anaxyrus boreas boreas) populations, representing combinations of logistical access (accessible, inaccessible) and breeding behavior (synchronous, asynchronous). We examine the bias and precision of survival and breeding probability estimates generated by survey designs that differ in effort and timing for these populations. Our findings indicate that the logistical access of a site and mismatch between the breeding behavior and survey design can greatly limit the ability to yield accurate and precise estimates of survival and breeding probabilities. Simulations similar to what we have performed can help researchers determine an optimal survey design(s) for their system before initiating sampling efforts.

Development and validation of a HPTLC method for simultaneous estimation of lornoxicam and thiocolchicoside in combined dosage form.

PubMed

Sahoo, Madhusmita; Syal, Pratima; Hable, Asawaree A; Raut, Rahul P; Choudhari, Vishnu P; Kuchekar, Bhanudas S

2011-07-01

To develop a simple, precise, rapid and accurate HPTLC method for the simultaneous estimation of Lornoxicam (LOR) and Thiocolchicoside (THIO) in bulk and pharmaceutical dosage forms. The separation of the active compounds from pharmaceutical dosage form was carried out using methanol:chloroform:water (9.6:0.2:0.2 v/v/v) as the mobile phase and no immiscibility issues were found. The densitometric scanning was carried out at 377 nm. The method was validated for linearity, accuracy, precision, LOD (Limit of Detection), LOQ (Limit of Quantification), robustness and specificity. The Rf values (±SD) were found to be 0.84 ± 0.05 for LOR and 0.58 ± 0.05 for THIO. Linearity was obtained in the range of 60-360 ng/band for LOR and 30-180 ng/band for THIO with correlation coefficients r(2) = 0.998 and 0.999, respectively. The percentage recovery for both the analytes was in the range of 98.7-101.2 %. The proposed method was optimized and validated as per the ICH guidelines.

Development and Validation of High Performance Liquid Chromatography Method for Determination Atorvastatin in Tablet

NASA Astrophysics Data System (ADS)

Yugatama, A.; Rohmani, S.; Dewangga, A.

2018-03-01

Atorvastatin is the primary choice for dyslipidemia treatment. Due to patent expiration of atorvastatin, the pharmaceutical industry makes copy of the drug. Therefore, the development methods for tablet quality tests involving atorvastatin concentration on tablets needs to be performed. The purpose of this research was to develop and validate the simple atorvastatin tablet analytical method by HPLC. HPLC system used in this experiment consisted of column Cosmosil C18 (150 x 4,6 mm, 5 µm) as the stationary reverse phase chomatography, a mixture of methanol-water at pH 3 (80:20 v/v) as the mobile phase, flow rate of 1 mL/min, and UV detector at wavelength of 245 nm. Validation methods were including: selectivity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). The results of this study indicate that the developed method had good validation including selectivity, linearity, accuracy, precision, LOD, and LOQ for analysis of atorvastatin tablet content. LOD and LOQ were 0.2 and 0.7 ng/mL, and the linearity range were 20 - 120 ng/mL.

UV Spectrophotometric Determination and Validation of Hydroquinone in Liposome.

PubMed

Khoshneviszadeh, Rabea; Fazly Bazzaz, Bibi Sedigheh; Housaindokht, Mohammad Reza; Ebrahim-Habibi, Azadeh; Rajabi, Omid

2015-01-01

The method has been developed and validated for the determination of hydroquinone in liposomal formulation. The samples were dissolved in methanol and evaluated in 293 nm. The validation parameters such as linearity, accuracy, precision, specificity, limit of detection (LOD) and limit of quantitation (LOQ) were determined. The calibration curve was linear in 1-50 µg/mL range of hydroquinone analyte with a regression coefficient of 0.9998. This study showed that the liposomal hydroquinone composed of phospholipid (7.8 %), cholesterol (1.5 %), alpha ketopherol (0.17 %) and hydroquinone (0.5 %) did not absorb wavelength of 293 nm if it diluted 500 times by methanol. The concentration of hydroquinone reached 10 µg/mL after 500 times of dilution. Furthermore, various validation parameters as per ICH Q2B guideline were tested and found accordingly. The recovery percentages of liposomal hydroquinone were found 102 ± 0.8, 99 ± 0.2 and 98 ± 0.4 for 80%, 100% and 120% respectively. The relative standard deviation values of inter and intra-day precisions were <%2. LOD and LOQ were 0.24 and 0.72 µg/mL respectively.

Towards the identification of alkaline phosphatase binding ligands in Li-Dan-Hua-Shi pills: A Box-Behnken design optimized affinity selection approach tandem with UHPLC-Q-TOF/MS analysis.

PubMed

Tao, Yi; Huang, Surun; Gu, Xianghui; Li, Weidong; Cai, Baochang

2018-05-30

Alkaline phosphatase conjugated magnetic microspheres were synthesized via amide reaction, and employed as an effective adsorbent in affinity selection of binding ligands followed by UHPLC-Q-TOF/MS analysis. The analytical validity of the developed approach was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 0.01-0.5 g L -1 with good determination coefficients (R 2  = 0.9992); limits of detection (LODs), 0.003 g L -1 ; and limits of quantitation (LOQ), 0.01 g L -1 . The precision (RSD%) of the proposed affinity selection approach was studied based on intra-day (0.8%) and inter-day (1.3%) precisions. Finally, the adsorbent was successfully applied to identification of binding ligands in Li-Dan-Hua-Shi pills and good recoveries were obtained in the range from 96.9 to 99.4% (RSDs 1.6-3.0%). Copyright © 2018 Elsevier B.V. All rights reserved.

Improving OCD time to solution using Signal Response Metrology

NASA Astrophysics Data System (ADS)

Fang, Fang; Zhang, Xiaoxiao; Vaid, Alok; Pandev, Stilian; Sanko, Dimitry; Ramanathan, Vidya; Venkataraman, Kartik; Haupt, Ronny

2016-03-01

In recent technology nodes, advanced process and novel integration scheme have challenged the precision limits of conventional metrology; with critical dimensions (CD) of device reduce to sub-nanometer region. Optical metrology has proved its capability to precisely detect intricate details on the complex structures, however, conventional RCWA-based (rigorous coupled wave analysis) scatterometry has the limitations of long time-to-results and lack of flexibility to adapt to wide process variations. Signal Response Metrology (SRM) is a new metrology technique targeted to alleviate the consumption of engineering and computation resources by eliminating geometric/dispersion modeling and spectral simulation from the workflow. This is achieved by directly correlating the spectra acquired from a set of wafers with known process variations encoded. In SPIE 2015, we presented the results of SRM application in lithography metrology and control [1], accomplished the mission of setting up a new measurement recipe of focus/dose monitoring in hours. This work will demonstrate our recent field exploration of SRM implementation in 20nm technology and beyond, including focus metrology for scanner control; post etch geometric profile measurement, and actual device profile metrology.

Validation of an enzyme-linked immunosorbent assay screening method and a liquid chromatography-tandem mass spectrometry confirmation method for the identification and quantification of ketamine and norketamine in urine samples from Malaysia.

PubMed

Harun, Norlida; Anderson, Robert A; Miller, Eleanor I

2009-01-01

An ELISA and a liquid chromatography-tandem mass spectrometry (LC-MS-MS) confirmation method were developed and validated for the identification and quantitation of ketamine and its major metabolite norketamine in urine samples. The Neogen ketamine microplate ELISA was optimized with respect to sample and enzyme conjugate volumes and the sample preincubation time before addition of the enzyme conjugate. The ELISA kit was validated to include an assessment of the dose-response curve, intra- and interday precision, limit of detection (LOD), and cross-reactivity. The sensitivity and specificity were calculated by comparison to the results from the validated LC-MS-MS confirmation method. An LC-MS-MS method was developed and validated with respect to LOD, lower limit of quantitation (LLOQ), linearity, recovery, intra- and interday precision, and matrix effects. The ELISA dose-response curve was a typical S-shaped binding curve, with a linear portion of the graph observed between 25 and 500 ng/mL for ketamine. The cross-reactivity of 200 ng/mL norketamine to ketamine was 2.1%, and no cross-reactivity was detected with 13 common drugs tested at 10,000 ng/mL. The ELISA LOD was calculated to be 5 ng/mL. Both intra- (n = 10) and interday (n = 50) precisions were below 5.0% at 25 ng/mL. The LOD for ketamine and norketamine was calculated statistically to be 0.6 ng/mL. The LLOQ values were also calculated statistically and were 1.9 ng/mL and 2.1 ng/mL for ketamine and norketamine, respectively. The test linearity was 0-1200 ng/mL with correlation coefficient (R(2)) > 0.99 for both analytes. Recoveries at 50, 500, and 1000 ng/mL range from 97.9% to 113.3%. Intra- (n = 5) and interday (n = 25) precisions between extracts for ketamine and norketamine were excellent (< 10%). Matrix effects analysis showed an average ion suppression of 5.7% for ketamine and an average ion enhancement of 13.0% for norketamine for urine samples collected from six individuals. A comparison of ELISA and LC-MS-MS results demonstrated a sensitivity, specificity, and efficiency of 100%. These results indicated that a cutoff value of 25 ng/mL ketamine in the ELISA screen is particularly suitable and reliable for urine testing in a forensic toxicology setting. Furthermore, both ketamine and norketamine were detected in all 34 urine samples collected from individuals socializing in pubs by the Royal Malaysian Police. Ketamine concentrations detected by LC-MS-MS ranged from 22 to 31,670 ng/mL, and norketamine concentrations ranged from 25 to 10,990 ng/mL. The concentrations of ketamine and norketamine detected in the samples are most ikely indicative of ketamine abuse.

Sensitive spectrofluorimetric determination of tizanidine in pharmaceutical preparations, human plasma and urine through derivatization with dansyl chloride.

PubMed

Ulu, Sevgi Tatar

2012-01-01

A sensitive spectrofluorimetric method was developed for the determination of tizanidine in human plasma, urine and pharmaceutical preparations. The method is based on reaction of tizanidine with 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride) in an alkaline medium to form a highly fluorescent derivative that was measured at 511 nm after excitation at 383 nm. The different experimental parameters affecting the fluorescence intensity of tizanidine was carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges 50-500 and 20-300 ng/mL for plasma and urine, respectively, detection limits of 1.81 and 0.54 ng/mL and quantification limits of 5.43 and 1.62 ng/mL for plasma and urine, respectively. The method presents good performance in terms of linearity, detection and quantification limits, precision, accuracy and specificity. The proposed method was successfully applied for the determination of tizanidine in pharmaceutical preparations. The results obtained were compared with a reference method, using t- and F-tests. Copyright © 2011 John Wiley & Sons, Ltd.

Method validation using weighted linear regression models for quantification of UV filters in water samples.

PubMed

da Silva, Claudia Pereira; Emídio, Elissandro Soares; de Marchi, Mary Rosa Rodrigues

2015-01-01

This paper describes the validation of a method consisting of solid-phase extraction followed by gas chromatography-tandem mass spectrometry for the analysis of the ultraviolet (UV) filters benzophenone-3, ethylhexyl salicylate, ethylhexyl methoxycinnamate and octocrylene. The method validation criteria included evaluation of selectivity, analytical curve, trueness, precision, limits of detection and limits of quantification. The non-weighted linear regression model has traditionally been used for calibration, but it is not necessarily the optimal model in all cases. Because the assumption of homoscedasticity was not met for the analytical data in this work, a weighted least squares linear regression was used for the calibration method. The evaluated analytical parameters were satisfactory for the analytes and showed recoveries at four fortification levels between 62% and 107%, with relative standard deviations less than 14%. The detection limits ranged from 7.6 to 24.1 ng L(-1). The proposed method was used to determine the amount of UV filters in water samples from water treatment plants in Araraquara and Jau in São Paulo, Brazil. Copyright © 2014 Elsevier B.V. All rights reserved.

Marine chemical technology and sensors for marine waters: potentials and limits.

PubMed

Moore, Tommy S; Mullaugh, Katherine M; Holyoke, Rebecca R; Madison, Andrew S; Yücel, Mustafa; Luther, George W

2009-01-01

A significant need exists for in situ sensors that can measure chemical species involved in the major processes of primary production (photosynthesis and chemosynthesis) and respiration. Some key chemical species are O2, nutrients (N and P), micronutrients (metals), pCO2, dissolved inorganic carbon (DIC), pH, and sulfide. Sensors need to have excellent detection limits, precision, selectivity, response time, a large dynamic concentration range, low power consumption, robustness, and less variation of instrument response with temperature and pressure, as well as be free from fouling problems (biological, physical, and chemical). Here we review the principles of operation of most sensors used in marine waters. We also show that some sensors can be used in several different oceanic environments to detect the target chemical species, whereas others are useful in only one environment because of various limitations. Several sensors can be used truly in situ, whereas many others involve water brought into a flow cell via tubing to the analyzer in the environment or aboard ship. Multi-element sensors that measure many chemical species in the same water mass should be targeted for further development.

Offline solid-phase extraction for preconcentration of pharmaceuticals and personal care products in environmental water and their simultaneous determination using the reversed phase high-performance liquid chromatography method.

PubMed

G Archana; Dhodapkar, Rita; Kumar, Anupama

2016-09-01

The present study reports a precise and simple offline solid-phase extraction (SPE) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of five representative and commonly present pharmaceuticals and personal care products (PPCPs), a new class of emerging pollutants in the aquatic environment. The target list of analytes including ciprofloxacin, acetaminophen, caffeine benzophenone and irgasan were separated by a simple HPLC method. The column used was a reversed-phase C18 column, and the mobile phase was 1 % acetic acid and methanol (20:80 v/v) under isocratic conditions, at a flow rate of 1 mL min(-1). The analytes were separated and detected within 15 min using the photodiode array detector (PDA). The linearity of the calibration curves were obtained with correlation coefficients 0.98-0.99.The limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and ruggedness demonstrated the reproducibility, specificity and sensitivity of the developed method. Prior to the analysis, the SPE was performed using a C18 cartridge to preconcentrate the targeted analytes from the environmental water samples. The developed method was applied to evaluate and fingerprint PPCPs in sewage collected from a residential engineering college campus, polluted water bodies such as Nag river and Pili river and the influent and effluent samples from a sewage treatment plant (STP) situated at Nagpur city, in the peak summer season. This method is useful for estimation of pollutants present in microquantities in the surface water bodies and treated sewage as compared to nanolevel pollutants detected by mass spectrometry (MS) detectors.

Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin

PubMed Central

Porel, A.; Haty, Sanjukta; Kundu, A.

2011-01-01

The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 μl. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R2 >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup. PMID:22131621

Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin.

PubMed

Porel, A; Haty, Sanjukta; Kundu, A

2011-01-01

The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 μl. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R(2) >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup.

Quality Analysis of Chlorogenic Acid and Hyperoside in Crataegi fructus

PubMed Central

Weon, Jin Bae; Jung, Youn Sik; Ma, Choong Je

2016-01-01

Background: Crataegi fructus is a herbal medicine for strong stomach, sterilization, and alcohol detoxification. Chlorogenic acid and hyperoside are the major compounds in Crataegi fructus. Objective: In this study, we established novel high-performance liquid chromatography (HPLC)-diode array detection analysis method of chlorogenic acid and hyperoside for quality control of Crataegi fructus. Materials and Methods: HPLC analysis was achieved on a reverse-phase C18 column (5 μm, 4.6 mm × 250 mm) using water and acetonitrile as mobile phase with gradient system. The method was validated for linearity, precision, and accuracy. About 31 batches of Crataegi fructus samples collected from Korea and China were analyzed by using HPLC fingerprint of developed HPLC method. Then, the contents of chlorogenic acid and hyperoside were compared for quality evaluation of Crataegi fructus. Results: The results have shown that the average contents (w/w %) of chlorogenic acid and hyperoside in Crataegi fructus collected from Korea were 0.0438% and 0.0416%, respectively, and the average contents (w/w %) of 0.0399% and 0.0325%, respectively. Conclusion: In conclusion, established HPLC analysis method was stable and could provide efficient quality evaluation for monitoring of commercial Crataegi fructus. SUMMARY Quantitative analysis method of chlorogenic acid and hyperoside in Crataegi fructus is developed by high.performance liquid chromatography.(HPLC).diode array detectionEstablished HPLC analysis method is validated with linearity, precision, and accuracyThe developed method was successfully applied for quantitative analysis of Crataegi fructus sample collected from Korea and China. Abbreviations used: HPLC: High-performance liquid chromatography, GC: Gas chromatography, MS: Mass spectrometer, LOD: Limits of detection, LOQ: Limits of quantification, RSD: Relative standard deviation, RRT: Relative retention time, RPA: Relation peak area. PMID:27076744

Simultaneous determination of chromones and coumarins in Radix Saposhnikoviae by high performance liquid chromatography with diode array and tandem mass detectors.

PubMed

Kim, Min Kyung; Yang, Dong-Hyug; Jung, Mihye; Jung, Eun Ha; Eom, Han Young; Suh, Joon Hyuk; Min, Jung Won; Kim, Unyong; Min, Hyeyoung; Kim, Jinwoong; Han, Sang Beom

2011-09-16

Methods using high performance liquid chromatography with diode array detection (HPLC-DAD) and tandem mass spectrometry (HPLC-MS/MS) were developed and validated for the simultaneous determination of 5 chromones and 6 coumarins: prim-O-glucosylcimifugin (1), cimifugin (2), nodakenin (3), 4'-O-β-d-glucosyl-5-O-methylvisamminol (4), sec-O-glucosylhamaudol (5), psoralen (6), bergapten (7), imperatorin (8), phellopterin (9), 3'-O-angeloylhamaudol (10) and anomalin (11), in Radix Saposhnikoviae. The separation conditions for HPLC-DAD were optimized using an Ascentis Express C18 (4.6 mm×100 mm, 2.7 μm particle size) fused-core column. The mobile phase was composed of 10% aqueous acetonitrile (A) and 90% acetonitrile (B) and the elution was performed under a gradient mode at a flow rate of 1.0 mL/min. The detection wavelength was set at 300 nm. The HPLC-DAD method yielded a base line separation of the 11 components in 50% methanol extract of Radix Saposhnikoviae with no interfering peaks detected. The HPLC-DAD method was validated in terms of linearity, accuracy and precision (intra- and inter-day), limit of quantification (LOQ), recovery, and robustness. Specific determination of the 11 components was also accomplished by a triple quadrupole tandem mass spectrometer equipped with an electrospray ionization (ESI) source. This HPLC-MS/MS method was also validated by determining the linearity, limit of quantification, accuracy, and precision. Quantification of the 11 components in 51 commercial Radix Saposhnikoviae samples was successfully performed using the developed HPLC-DAD method. The identity, batch-to-batch consistency, and authenticity of Radix Saposhnikoviae were successfully monitored by the proposed HPLC-DAD and HPLC-MS/MS methods. Copyright © 2011 Elsevier B.V. All rights reserved.

Determination of carbamazepine in serum and saliva samples by high performance liquid chromatography with ultraviolet detection.

PubMed

Dordević, Snezana; Kilibarda, Vesna; Stojanović, Tomislav

2009-05-01

Carbamazepine is antiepileptic drug widely used for the treatment of epilepsy. Due to low therapeutic index of carbamazepine there is a need for routine measuring its concentrations in biological fluids. The aim of the study was to describe a method for concomitant determination of carbamazepine in the serum and saliva. Separation of the drug from matrix is achieved by reversed-phase chromatography on a C18 column, with a mobile phase of methanol-water-acetic acid (65:34:1) at a flow-rate of 1.0 ml/min. Detection was effected by ultra-violet absorption at 285 nm. The total run time was 5 min. Samples were prepared by alkaline extraction (pH 10) using chlorophorm. Calibration curves were in the range 0.1-5 microg/mL for serum and saliva samples. Mean recoveries of spiked serum and saliva were 97.59 and 92.30%, respectively. Limits of detection (LOD) of carbamazepine in serum and saliva were 0.166 and 0.178 microg/mL, respectively. Limits of quantification (LOQ) in the serum and saliva were 0.237 and 0.226 microg/mL, respectively. The method precision was carried out with coefficient of variation of 2.10% and 4.03% for the serum and saliva, respectively. The obtained data showed that there was a strong correlation between saliva and serum concentrations (r = 0.9481, p < 0.001). The method described here is rapid, precise, accurate and simple, and can be used for quantitative determination of carbamazepine in human serum and saliva after therapy applying. Saliva samples could be used as an alternative matrix for therapeutic drug monitoring of this antiepileptic drug.

Novel centrifugal technology for measuring sperm concentration in the home.

PubMed

Schaff, Ulrich Y; Fredriksen, Laura L; Epperson, Jon G; Quebral, Tiffany R; Naab, Sara; Sarno, Mark J; Eisenberg, Michael L; Sommer, Greg J

2017-02-01

To evaluate the analytical performance and usability of the Trak Male Fertility Testing System, a semiquantitative (categorical) device recently US Food and Drug Administration (FDA)-cleared for measuring sperm concentration in the home by untrained users. A three-site clinical trial comparing self-reported lay user results versus reference results obtained by computer-aided semen analysis (CASA). Simulated home use environments at fertility centers and urologist offices. A total of 239 untrained users. None. Sperm concentration results reported from self-testing lay users and laboratory reference method by CASA were evaluated semiquantitatively against the device's clinical cutoffs of 15 M/mL (current World Health Organization cutoff) and 55 M/mL (associated with faster time to pregnancy). Additional reported metrics include assay linearity, precision, limit of detection, and ease-of-use ratings from lay users. Lay users achieved an accuracy (versus the reference) of 93.3% (95% confidence interval [CI] 84.1%-97.4%) for results categorized as ≤15 M/mL, 82.4% (95% CI 73.3%-88.9%) for results categorized as 15-55 M/mL, and 95.5% (95% CI 88.9%-98.2%) for results categorized as >55 M/mL. When measured quantitatively, Trak results had a strong linear correlation with CASA measurements (r = 0.99). The precision and limit of detection studies show that the device has adequate reproducibility and detection range for home use. Subjects generally rated the device as easy to use. The Trak System is an accurate tool for semiquantitatively measuring sperm concentration in the home. The system may enable screening and longitudinal assessment of sperm concentration at home. ClinicalTrials.gov identifier: NCT02475395. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Simultaneous Determination of Crypto-Chlorogenic Acid, Isoquercetin, and Astragalin Contents in Moringa oleifera Leaf Extracts by TLC-Densitometric Method

PubMed Central

Vongsak, Boonyadist; Sithisarn, Pongtip; Gritsanapan, Wandee

2013-01-01

Moringa oleifera Lamarck (Moringaceae) is used as a multipurpose medicinal plant for the treatment of various diseases. Isoquercetin, astragalin, and crypto-chlorogenic acid have been previously found to be major active components in the leaves of this plant. In this study, a thin-layer-chromatography (TLC-)densitometric method was developed and validated for simultaneous quantification of these major components in the 70% ethanolic extracts of M. oleifera leaves collected from 12 locations. The average amounts of crypto-chlorogenic acid, isoquercetin, and astragalin were found to be 0.0473, 0.0427, and 0.0534% dry weight, respectively. The method was validated for linearity, precision, accuracy, limit of detection, limit of quantitation, and robustness. The linearity was obtained in the range of 100–500 ng/spot with a correlation coefficient (r) over 0.9961. Intraday and interday precisions demonstrated relative standard deviations of less than 5%. The accuracy of the method was confirmed by determining the recovery. The average recoveries of each component from the extracts were in the range of 98.28 to 99.65%. Additionally, the leaves from Chiang Mai province contained the highest amounts of all active components. The proposed TLC-densitometric method was simple, accurate, precise, and cost-effective for routine quality controlling of M. oleifera leaf extracts. PMID:23533530

Stereospecific analysis of sakuranetin by high-performance liquid chromatography: pharmacokinetic and botanical applications.

PubMed

Takemoto, Jody K; Remsberg, Connie M; Yáñez, Jaime A; Vega-Villa, Karina R; Davies, Neal M

2008-11-01

A stereospecific method for analysis of sakuranetin was developed. Separation was accomplished using a Chiralpak AD-RH column with UV (ultraviolet) detection at 288 nm. The stereospecific linear calibration curves ranged from 0.5 to 100 microg/mL. The mean extraction efficiency was >98%. Precision of the assay was <12% (relative standard deviation (R.S.D.)%), and within 10% at the limit of quantitation (0.5 microg/mL). Bias of the assay was lower than 10%, and within 5% at the limit of quantitation. The assay was applied successfully to pharmacokinetic quantification in rats, and the stereospecific quantification in oranges, grapefruit juice, and matico (Piper aduncum L.).

Trojans and Plutinos as probes of planet building

NASA Astrophysics Data System (ADS)

Alexandersen, Mike; Gladman, B.; Kavelaars, J. J.; Petit, J.; Gwyn, S.; Greenstreet, S.

2013-10-01

Planetesimals formed during planet formation are the building blocks of giant planet cores; some are preserved as large trans-neptunian objects (TNOs). Previous work has shown steep power-law distributions for TNOs of diameters > 100 km. Recent results claim a dramatic roll-over or divot in the size distribution of Neptunian Trojans and scattering TNOs, with a significant lack of intermediate-size D<100 km planetesimals. One theoretical explanation for this is that planetesimals were born big, skipping the intermediate sizes, contrary to the classical understanding of planetesimal formation. Exploration of the TNO size distribution requires more precisely calibrated detections in order to improve statistics on these results. We have searched a 32 sq.deg. area near RA=2 hr to a r-band limiting magnitude of m_r=24.6 using the Canada-France-Hawaii Telescope. This coverage was near the Neptunian L4 region to maximise our detection rate, as this is where Trojans reside and where Plutinos (and several other resonant populations) come to perihelion. Our program successfully detected, tracked and characterized 77 TNOs and Centaurs for up to 17 months, giving us the high-quality orbits needed for precise modelling. Among our detections were one Uranian Trojan (see Alexandersen et al. 2013 & abstract by Greenstreet et al.), two Neptunian Trojans, 18 Plutinos and many other resonant objects. This meticulously calibrated survey and the high-quality orbits obtained for the detected objects allow us to create and test models of TNO size and orbital distributions. We test these models using a survey simulator, which simulates the detectability of model objects, accounting for the constraints and biases of our survey. Thus, we set precise constraints on the size and orbital distributions of the Neptunian Trojans, Plutinos and other resonant populations. We show that the Plutino inclination distribution is dynamically colder than found by the Canada-France Ecliptic Plane Survey. We also show that the Plutino size distribution cannot continue with the same slope for diameters < 100 km; a best-fit alternative will be presented. This research was supported by the Canadian National Sciences and Engineering Research Council.

Laser fluorometric analysis of plants for uranium exploration

USGS Publications Warehouse

Harms, T.F.; Ward, F.N.; Erdman, J.A.

1981-01-01

A preliminary test of biogeochemical exploration for locating uranium occurrences in the Marfa Basin, Texas, was conducted in 1978. Only 6 of 74 plant samples (mostly catclaw mimosa, Mimosa biuncifera) contained uranium in amounts above the detection limit (0.4 ppm in the ash) of the conventional fluorometric method. The samples were then analyzed using a Scintrex UA-3 uranium analyzer* * Use of trade names in this paper is for descriptive purposes only and does not constitute endorsement by the U.S. Geological Survey. - an instrument designed for direct analysis of uranium in water, and which can be conveniently used in a mobile field laboratory. The detection limit for uranium in plant ash (0.05 ppm) by this method is almost an order of magnitude lower than with the fluorometric conventional method. Only 1 of the 74 samples contained uranium below the detection limit of the new method. Accuracy and precision were determined to be satisfactory. Samples of plants growing on mineralized soils and nonmineralized soils show a 15-fold difference in uranium content; whereas the soils themselves (analyzed by delayed neutron activation analysis) show only a 4-fold difference. The method involves acid digestion of ashed tissue, extraction of uranium into ethyl acetate, destruction of the ethyl acetate, dissolution of the residue in 0.005% nitric acid, and measurement. ?? 1981.

An improvement of the GPS buoy system for detecting tsunami at far offshore

NASA Astrophysics Data System (ADS)

Kato, T.; Terada, Y.; Nagai, T.; Kawaguchi, K.; Koshimura, S.; Matsushita, Y.

2012-12-01

We have developed a GPS buoy system for detecting a tsunami before its arrival at coasts and thereby mitigating tsunami disaster. The system was first deployed in 1997 for a short period in the Sagami bay, south of Tokyo, for basic experiments, and then deployed off Ofunato city, northeastern part of Japan, for the period 2001-2004. The system was then established at about 13km south of Cape Muroto, southwestern part of Japan, since 2004. Five tsunamis of about 10cm have been observed in these systems, including 2001 Peru earthquake (Mw8.3), 2003 Tokachi-oki earthquake (Mw8.3), 2004 Off Kii Peninsula earthquake (Mw7.4), 2010 Chile earthquake (Mw8.8), and 2011 Tohoku-Oki earthquake (Mw9.0). These experiments clearly showed that GPS buoy is capable of detecting tsunami with a few centimeter accuracy and can be monitored in near real time by applying an appropriate filter, real-time data transmission using radio and dissemination of obtained records of sea surface height changes through internet. Considering that the system is a powerful tool to monitor sea surface variations due to wind as well as tsunami, the Ministry of Land, Infrastructure, Transport and Tourism implemented the system in a part of the Nationwide Ocean Wave information network for Ports and HArbourS (NOWPHAS) system and deployed the system at 15 sites along the coasts around the Japanese Islands. The system detected the tsunami due to the 11th March 2011 Tohoku-Oki earthquake with higher than 6m of tsunami height at the site Off South Iwate (Kamaishi). The Japan Meteorological Agency that was monitoring the record updated the level of the tsunami warning to the greatest value due to the result. Currently, the GPS buoy system uses a RTK-GPS which requires a land base for obtaining precise location of the buoy by a baseline analysis. This algorithm limits the distance of the buoy to, at most, 20km from the coast as the accuracy of positioning gets much worse as the baseline distance becomes longer than 20km. This limits the lead time for letting coastal residents to evacuate from the coast only about 10 minutes after the detection of tsunami at a GPS buoy. This requires us to improve the system to put the buoy much farther from the coast. In order to solve this problem, we have introduced a new algorithm of precise point positioning with ambiguity resolution (PPP-AR) method and point precise variance detection (PVD) method for estimating the precise location of the buoy. As these method does not require land base station, it may allow us to deploy a buoy much farther than 100km offshore observation. Also, an open source program package (RTKLIB) is introduced for kinematic analysis for a long baseline. A new experiment using this system has started about 40km south off Cape Muroto in April 2012. One of buoys called as "Kuroshio Bokujo", which is used as a fish bed by Kochi Prefecture, is used for this purpose. The positioning results are exhibited in real time on the internet.

Using confidence intervals to evaluate the focus alignment of spectrograph detector arrays.

PubMed

Sawyer, Travis W; Hawkins, Kyle S; Damento, Michael

2017-06-20

High-resolution spectrographs extract detailed spectral information of a sample and are frequently used in astronomy, laser-induced breakdown spectroscopy, and Raman spectroscopy. These instruments employ dispersive elements such as prisms and diffraction gratings to spatially separate different wavelengths of light, which are then detected by a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) detector array. Precise alignment along the optical axis (focus position) of the detector array is critical to maximize the instrumental resolution; however, traditional approaches of scanning the detector through focus lack a quantitative measure of precision, limiting the repeatability and relying on one's experience. Here we propose a method to evaluate the focus alignment of spectrograph detector arrays by establishing confidence intervals to measure the alignment precision. We show that propagation of uncertainty can be used to estimate the variance in an alignment, thus providing a quantitative and repeatable means to evaluate the precision and confidence of an alignment. We test the approach by aligning the detector array of a prototype miniature echelle spectrograph. The results indicate that the procedure effectively quantifies alignment precision, enabling one to objectively determine when an alignment has reached an acceptable level. This quantitative approach also provides a foundation for further optimization, including automated alignment. Furthermore, the procedure introduced here can be extended to other alignment techniques that rely on numerically fitting data to a model, providing a general framework for evaluating the precision of alignment methods.

Optical Vector Receiver Operating Near the Quantum Limit

NASA Astrophysics Data System (ADS)

Vilnrotter, V. A.; Lau, C.-W.

2005-05-01

An optical receiver concept for binary signals with performance approaching the quantum limit at low average-signal energies is developed and analyzed. A conditionally nulling receiver that reaches the quantum limit in the absence of background photons has been devised by Dolinar. However, this receiver requires ideal optical combining and complicated real-time shaping of the local field; hence, it tends to be difficult to implement at high data rates. A simpler nulling receiver that approaches the quantum limit without complex optical processing, suitable for high-rate operation, had been suggested earlier by Kennedy. Here we formulate a vector receiver concept that incorporates the Kennedy receiver with a physical beamsplitter, but it also utilizes the reflected signal component to improve signal detection. It is found that augmenting the Kennedy receiver with classical coherent detection at the auxiliary beamsplitter output, and optimally processing the vector observations, always improves on the performance of the Kennedy receiver alone, significantly so at low average-photon rates. This is precisely the region of operation where modern codes approach channel capacity. It is also shown that the addition of background radiation has little effect on the performance of the coherent receiver component, suggesting a viable approach for near-quantum-limited performance in high background environments.

Extracting laboratory test information from biomedical text

PubMed Central

Kang, Yanna Shen; Kayaalp, Mehmet

2013-01-01

Background: No previous study reported the efficacy of current natural language processing (NLP) methods for extracting laboratory test information from narrative documents. This study investigates the pathology informatics question of how accurately such information can be extracted from text with the current tools and techniques, especially machine learning and symbolic NLP methods. The study data came from a text corpus maintained by the U.S. Food and Drug Administration, containing a rich set of information on laboratory tests and test devices. Methods: The authors developed a symbolic information extraction (SIE) system to extract device and test specific information about four types of laboratory test entities: Specimens, analytes, units of measures and detection limits. They compared the performance of SIE and three prominent machine learning based NLP systems, LingPipe, GATE and BANNER, each implementing a distinct supervised machine learning method, hidden Markov models, support vector machines and conditional random fields, respectively. Results: Machine learning systems recognized laboratory test entities with moderately high recall, but low precision rates. Their recall rates were relatively higher when the number of distinct entity values (e.g., the spectrum of specimens) was very limited or when lexical morphology of the entity was distinctive (as in units of measures), yet SIE outperformed them with statistically significant margins on extracting specimen, analyte and detection limit information in both precision and F-measure. Its high recall performance was statistically significant on analyte information extraction. Conclusions: Despite its shortcomings against machine learning methods, a well-tailored symbolic system may better discern relevancy among a pile of information of the same type and may outperform a machine learning system by tapping into lexically non-local contextual information such as the document structure. PMID:24083058

Improving quantitative gas chromatography-electron ionization mass spectrometry results using a modified ion source: demonstration for a pharmaceutical application.

PubMed

D'Autry, Ward; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Van Schepdael, Ann

2011-07-01

Gas chromatography-mass spectrometry is a well established analytical technique. However, mass spectrometers with electron ionization sources may suffer from signal drifts, hereby negatively influencing quantitative performance. To demonstrate this phenomenon for a real application, a static headspace-gas chromatography method in combination with electron ionization-quadrupole mass spectrometry was optimized for the determination of residual dichloromethane in coronary stent coatings. Validating the method, the quantitative performance of an original stainless steel ion source was compared to that of a modified ion source. Ion source modification included the application of a gold coating on the repeller and exit plate. Several validation aspects such as limit of detection, limit of quantification, linearity and precision were evaluated using both ion sources. It was found that, as expected, the stainless steel ion source suffered from signal drift. As a consequence, non-linearity and high RSD values for repeated analyses were obtained. An additional experiment was performed to check whether an internal standard compound would lead to better results. It was found that the signal drift patterns of the analyte and internal standard were different, consequently leading to high RSD values for the response factor. With the modified ion source however, a more stable signal was observed resulting in acceptable linearity and precision. Moreover, it was also found that sensitivity improved compared to the stainless steel ion source. Finally, the optimized method with the modified ion source was applied to determine residual dichloromethane in the coating of coronary stents. The solvent was detected but found to be below the limit of quantification. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

Development and validation of a method for mercury determination in seawater for the process control of a candidate certified reference material.

PubMed

Sánchez, Raquel; Snell, James; Held, Andrea; Emons, Hendrik

2015-08-01

A simple, robust and reliable method for mercury determination in seawater matrices based on the combination of cold vapour generation and inductively coupled plasma mass spectrometry (CV-ICP-MS) and its complete in-house validation are described. The method validation covers parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), trueness, repeatability, intermediate precision and robustness. A calibration curve covering the whole working range was achieved with coefficients of determination typically higher than 0.9992. The repeatability of the method (RSDrep) was 0.5 %, and the intermediate precision was 2.3 % at the target mass fraction of 20 ng/kg. Moreover, the method was robust with respect to the salinity of the seawater. The limit of quantification was 2.7 ng/kg, which corresponds to 13.5 % of the target mass fraction in the future certified reference material (20 ng/kg). An uncertainty budget for the measurement of mercury in seawater has been established. The relative expanded (k = 2) combined uncertainty is 6 %. The performance of the validated method was demonstrated by generating results for process control and a homogeneity study for the production of a candidate certified reference material.

Determination of some phenolic compounds in red wine by RP-HPLC: method development and validation.

PubMed

Burin, Vívian Maria; Arcari, Stefany Grützmann; Costa, Léa Luzia Freitas; Bordignon-Luiz, Marilde T

2011-09-01

A methodology employing reversed-phase high-performance liquid chromatography (RP-HPLC) was developed and validated for simultaneous determination of five phenolic compounds in red wine. The chromatographic separation was carried out in a C(18) column with water acidify with acetic acid (pH 2.6) (solvent A) and 20% solvent A and 80% acetonitrile (solvent B) as the mobile phase. The validation parameters included: selectivity, linearity, range, limits of detection and quantitation, precision and accuracy, using an internal standard. All calibration curves were linear (R(2) > 0.999) within the range, and good precision (RSD < 2.6%) and recovery (80-120%) was obtained for all compounds. This method was applied to quantify phenolics in red wine samples from Santa Catarina State, Brazil, and good separation peaks for phenolic compounds in these wines were observed.

Precision cosmology from future lensed gravitational wave and electromagnetic signals.

PubMed

Liao, Kai; Fan, Xi-Long; Ding, Xuheng; Biesiada, Marek; Zhu, Zong-Hong

2017-10-27

The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. The Einstein telescope is expected to produce 10 4 -10 5 gravitational wave detections per year, 50-100 of which will be lensed. Here, we report a waveform-independent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain. We demonstrate that just 10 such systems can provide a Hubble constant uncertainty of 0.68% for a flat lambda cold dark matter universe in the era of third-generation ground-based detectors.

Comparative evaluation of a laboratory developed real-time PCR assay and the RealStar® HHV-6 PCR Kit for quantitative detection of human herpesvirus 6.

PubMed

Yip, Cyril C Y; Sridhar, Siddharth; Cheng, Andrew K W; Fung, Ami M Y; Cheng, Vincent C C; Chan, Kwok-Hung; Yuen, Kwok-Yung

2017-08-01

HHV-6 reactivation in immunocompromised patients is common and may be associated with serious morbidity and mortality; therefore, early detection and initiation of therapy might be of benefit. Real-time PCR assays allow for early identification of HHV-6 reactivation to assist in providing a timely response. Thus, we compared the performance of an in-house developed HHV-6 quantitative PCR assay with a commercially available kit, the RealStar ® HHV-6 PCR Kit. The analytical sensitivity, analytical specificity, linearity, precision and accuracy of the in-house developed HHV-6 qPCR assay were evaluated. The diagnostic performance of the in-house HHV-6 qPCR assay was compared with the RealStar ® HHV-6 PCR Kit, using 72 clinical specimens and 17 proficiency testing samples. Linear regression analysis of the quantitative results showed a dynamic range from 2 to 10 log 10 copies/ml and a coefficient of determination (R 2 ) of 0.999 for the in-house assay. A dilution series demonstrated a limit of detection and a limit of quantification of 1.7 log 10 and 2 log 10 copies/ml, respectively. The precision of the assay was highly reproducible among runs with coefficients of variance (CV) ranging from 0.27% to 4.37%. A comparison of 27 matched samples showed an excellent correlation between the quantitative viral loads measured by the in-house HHV-6 qPCR assay and the RealStar ® HHV-6 PCR Kit (R 2 =0.926; P<0.0001), with an average bias of -0.24 log 10 copies/ml. The in-house developed HHV-6 qPCR method is a sensitive and reliable assay with lower cost for the detection and quantification of HHV-6 DNA when compared to the RealStar ® HHV-6 PCR Kit. Copyright © 2017 Elsevier B.V. All rights reserved.

A Robust Static Headspace GC-FID Method to Detect and Quantify Formaldehyde Impurity in Pharmaceutical Excipients

PubMed Central

Al-Khayat, Mohammad Ammar; Karabet, Francois; Al-Mardini, Mohammad Amer

2018-01-01

Formaldehyde is a highly reactive impurity that can be found in many pharmaceutical excipients. Trace levels of this impurity may affect drug product stability, safety, efficacy, and performance. A static headspace gas chromatographic method was developed and validated to determine formaldehyde in pharmaceutical excipients after an effective derivatization procedure using acidified ethanol. Diethoxymethane, the derivative of formaldehyde, was then directly analyzed by GC-FID. Despite the simplicity of the developed method, however, it is characterized by its specificity, accuracy, and precision. The limits of detection and quantification of formaldehyde in the samples were of 2.44 and 8.12 µg/g, respectively. This method is characterized by using simple and economic GC-FID technique instead of MS detection, and it is successfully used to analyze formaldehyde in commonly used pharmaceutical excipients. PMID:29686930

Liquid chromatographic determination of 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one in human plasma with fluorescence detection.

PubMed

Cheng, H; Pittman, K A; Dandekar, K A

1987-12-01

A simple and sensitive assay for quantitating 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (1; BMY 26517) in human plasma was developed using high-performance liquid chromatography with fluorescence detection. The method involves precipitation of protein and reversed-phase chromatography. The method is linear in the range of 4.3-429 ng/mL of 1, and the limit of detection is 0.4 ng/mL. The day-to-day precision values of this method at 25.7 and 386 ng/mL are 2.1 and 2.6%, respectively. The day-to-day accuracy values at these concentrations are 99.7 and 99.8%, respectively. The recovery of 1 is 98.3%.

μ-PADs for detection of chemical warfare agents.

PubMed

Pardasani, Deepak; Tak, Vijay; Purohit, Ajay K; Dubey, D K

2012-12-07

Conventional methods of detection of chemical warfare agents (CWAs) based on chromogenic reactions are time and solvent intensive. The development of cost, time and solvent effective microfluidic paper based analytical devices (μ-PADs) for the detection of nerve and vesicant agents is described. The detection of analytes was based upon their reactions with rhodamine hydroxamate and para-nitrobenzyl pyridine, producing red and blue colours respectively. Reactions were optimized on the μ-PADs to produce the limits of detection (LODs) as low as 100 μM for sulfur mustard in aqueous samples. Results were quantified with the help of a simple desktop scanner and Photoshop software. Sarin achieved a linear response in the two concentration ranges of 20-100 mM and 100-500 mM, whereas the response of sulfur mustard was found to be linear in the concentration range of 10-75 mM. Results were precise enough to establish the μ-PADs as a valuable tool for security personnel fighting against chemical terrorism.

Evaluation of a dual-probe real time PCR system for detection of mandarin in commercial orange juice.

PubMed

Pardo, Miguel Angel

2015-04-01

A dual-probe real time PCR assay, based on the simultaneous detection of two TaqMan® probes, was evaluated for the detection of mandarin in orange juice. A single conserved polymorphism, located at the 314 position of intron belongs to chloroplast trnL gene, was confirmed by sequencing in 30 mandarin, 28 orange cultivars and 13 hybrids. The assay was also successfully evaluated in a blind trial against analysing 60 samples from different industrial processes in different countries around the world. The detection limit of the assay was established in 1% presence of mandarin detectable in processed orange juice and with a 100% precision. The quantitative application of the assay on citrus mixtures was also investigated, pointing out that the number of chloroplast DNA copies is too variable for its possible use as quantitative analysis. This assay can be employed as a routine methodology to control the accidental mixing during industrial processes and to deter intentional fraud. Copyright © 2014 Elsevier Ltd. All rights reserved.

Liquid crystal based biosensors for bile acid detection

NASA Astrophysics Data System (ADS)

He, Sihui; Liang, Wenlang; Tanner, Colleen; Fang, Jiyu; Wu, Shin-Tson

2013-03-01

The concentration level of bile acids is a useful indicator for early diagnosis of liver diseases. The prevalent measurement method in detecting bile acids is the chromatography coupled with mass spectrometry, which is precise yet expensive. Here we present a biosensor platform based on liquid crystal (LC) films for the detection of cholic acid (CA). This platform has the advantage of low cost, label-free, solution phase detection and simple analysis. In this platform, LC film of 4-Cyano-4'-pentylbiphenyl (5CB) was hosted by a copper grid supported with a polyimide-coated glass substrate. By immersing into sodium dodecyl sulfate (SDS) solution, the LC film was coated with SDS which induced a homeotropic anchoring of 5CB. Addition of CA introduced competitive adsorption between CA and SDS at the interface, triggering a transition from homeotropic to homogeneous anchoring. The detection limit can be tuned by changing the pH value of the solution from 12uM to 170uM.

Quantification of ethanol in plasma by electrochemical detection with an unmodified screen printed carbon electrode

NASA Astrophysics Data System (ADS)

Tian, Gang; Zhang, Xiao-Qing; Zhu, Ming-Song; Zhang, Zhong; Shi, Zheng-Hu; Ding, Min

2016-03-01

Simple, rapid and accurate detection of ethanol concentration in blood is very crucial in the diagnosis and management of potential acute ethanol intoxication patients. A novel electrochemical detection method was developed for the quantification of ethanol in human plasma with disposable unmodified screen-printed carbon electrode (SPCE) without sample preparation procedure. Ethanol was detected indirectly by the reaction product of ethanol dehydrogenase (ADH) and cofactor nicotinamide adenine dinucleotide (NAD+). Method validation indicated good quantitation precisions with intra-day and inter-day relative standard deviations of ≤9.4% and 8.0%, respectively. Ethanol concentration in plasma is linear ranging from 0.10 to 3.20 mg/mL, and the detection limit is 40.0 μg/mL (S/N > 3). The method shows satisfactory correlation with the reference method of headspace gas chromatography in twenty human plasma samples (correlation coefficient 0.9311). The proposed method could be applied to diagnose acute ethanol toxicity or ethanol-related death.

Quantification of ethanol in plasma by electrochemical detection with an unmodified screen printed carbon electrode

PubMed Central

Tian, Gang; Zhang, Xiao-Qing; Zhu, Ming-Song; Zhang, Zhong; Shi, Zheng-Hu; Ding, Min

2016-01-01

Simple, rapid and accurate detection of ethanol concentration in blood is very crucial in the diagnosis and management of potential acute ethanol intoxication patients. A novel electrochemical detection method was developed for the quantification of ethanol in human plasma with disposable unmodified screen-printed carbon electrode (SPCE) without sample preparation procedure. Ethanol was detected indirectly by the reaction product of ethanol dehydrogenase (ADH) and cofactor nicotinamide adenine dinucleotide (NAD+). Method validation indicated good quantitation precisions with intra-day and inter-day relative standard deviations of ≤9.4% and 8.0%, respectively. Ethanol concentration in plasma is linear ranging from 0.10 to 3.20 mg/mL, and the detection limit is 40.0 μg/mL (S/N > 3). The method shows satisfactory correlation with the reference method of headspace gas chromatography in twenty human plasma samples (correlation coefficient 0.9311). The proposed method could be applied to diagnose acute ethanol toxicity or ethanol-related death. PMID:27006081

An Astronomical Test of CCD Photometric Precision

NASA Technical Reports Server (NTRS)

Koch, David G.; Dunham, Edward W.; Borucki, William J.; Jenkins, Jon M.

2001-01-01

Ground-based differential photometry is limited to a precision of order 10(exp -3) because of atmospheric effects. A space-based photometer should be limited only by the inherent instrument precision and shot noise. Laboratory tests have shown that a precision of order 10-5 is achievable with commercially available charged coupled devices (CCDs). We have proposed to take this one step further by performing measurements at a telescope using a Wollaston prism as a beam splitter First-order atmospheric effects (e.g., extinction) will appear to be identical in the two images of each star formed by the prism and will be removed in the data analysis. This arrangement can determine the precision that is achievable under the influence of second-order atmospheric effects (e.g., variable point-spread function (PSF) from seeing). These telescopic observations will thus provide a lower limit to the precision that can be realized by a space-based differential photometer.

Multiple-Baseline Detection of a Geostationary Satellite with the Navy Precision Optical Interferometer

DTIC Science & Technology

2015-01-01

Multiple-baseline detection of a geostationary satellite with the Navy Precision Optical Interferometer J. Thomas Armstronga, Ellyn K. Bainesa...observations of a geostationary satellite using the Navy Precision Optical Inter- ferometer (NPOI) during the glint season of March 2015. We succeeded in...the second night. These baseline lengths correspond to a resolution of ∼4 m at geostationary altitude. This is the first multiple-baseline

Simultaneous determination of four neuroprotective compounds of Tilia amurensis by high performance liquid chromatography coupled with diode array detector

PubMed Central

Lee, Bohyung; Weon, Jin Bae; Yun, Bo-Ra; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Background: Tilia amurensis consists of various compounds, such as flavonoids and terpenoids. Objective: A simple and reliable high performance liquid chromatography (HPLC) coupled with the diode array detector (DAD) method has been established for simultaneous determination of epicatechin, nudiposide, lyoniside, and scopoletin isolated from Tilia amurensis. Materials and Methods: Optimum separations were obtained with a SHISEIDO C18 column by gradient eluton, with 0.1% Trifluoroacetic acid (TFA) water-methanol as the mobile phase. The gradient elution system was completed within 40 minutes. The flow rate and detection wavelength were 1 mL/minute, 205 nm, 250 nm, and 280 nm, respectively. Results: Validation of the analytical method was evaluated by linearity, precision, and the accuracy test. The calibration curve was linear over the established range with R2 > 0.997. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01-15.20 μg/mL and 0.03-46.06 μg/mL. The method exhibited an intraday and interday precision range of 96.25-105.66% and 93.52-109.92%, respectively (RSD <2.80%). The recoveries and relative standard deviation (RSD) of the four compounds in Tilia amurensis were in the range of 90.42-104.84% and 0.2-2.58%. Conclusion: This developed method was accurate and reliable for the quality evaluation of the four compounds isolated from Tilia amurensis. PMID:25210303

Analysis of antithyroid drugs in surface water by using liquid chromatography-tandem mass spectrometry.

PubMed

Pérez-Fernández, Virginia; Marchese, Stefano; Gentili, Alessandra; García, María Ángeles; Curini, Roberta; Caretti, Fulvia; Perret, Daniela

2014-11-07

This paper describes development and validation of a new method for the simultaneous determination of six antithyroid drugs (ATDs) in surface waters by using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Target compounds include two ATD classes: thiouracil derivatives (thiouracil (TU), methyl-thiouracil (MTU), propyl-thiouracil (PTU), phenyl-thiouracil (PhTU)) and imidazole derivatives (tapazole (TAP), and mercaptobenzimidazole (MBI)). Sensitivity and selectivity of the LC-multiple reaction monitoring (MRM) analysis allowed applying a simple pre-concentration procedure and "shooting" the concentrated sample into the LC-MS/MS system without any other treatment. Recoveries were higher than 75% for all analytes. Intra-day precision and inter-day precision, calculated as relative standard deviation (RSD), were below 19 and 22%, respectively. Limits of detection (LODs) ranged from 0.05 to 0.25 μg/L; limits of quantitation (LOQs) varied between 0.15 and 0.75 μg/L. The validated method was successfully applied to the analysis of ATD residues in surface water samples collected from the Tiber River basin and three lakes of Lazio (central Italy). The analytes were quantified based on matrix-matched calibration curves with mercaptobenzimidazole-d4 (MBI-d4) as the internal standard (IS). The most widespread compound was TAP, one of the most common ATDs used in human medicine, but also TU and MBI were often detected in the analysed samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Stability-indicating method for simultaneous estimation of olmesartan medoxomile, amlodipine besylate and hydrochlorothiazide by RP-HPLC in tablet dosage form.

PubMed

Jain, P S; Patel, M K; Gorle, A P; Chaudhari, A J; Surana, S J

2012-09-01

A simple, specific, accurate and precise stability-indicating reversed-phase high-performance liquid chromatographic method was developed for simultaneous estimation of olmesartan medoxomile (OLME), amlodipine besylate (AMLO) and hydrochlorothiazide (HCTZ) in tablet dosage form. The method was developed using an RP C18 base deactivated silica column (250 × 4.6 mm, 5 µm) with a mobile phase consisting of triethylamine (pH 3.0) adjusted with orthophosphoric acid (A) and acetonitrile (B), with a timed gradient program of T/%B: 0/30, 7/70, 8/30, 10/30 with a flow rate of 1.4 mL/min. Ultraviolet detection was used at 236 nm. The retention times for OLME, AMLO and HCTZ were found to be 6.72, 4.28 and 2.30, respectively. The proposed method was validated for precision, accuracy, linearity, range, robustness, ruggedness and force degradation study. The calibration curves of OLME, AMLO and HCTZ were linear over the range of 50-150, 12.5-37.5 and 31-93 µg/mL, respectively. The method was found to be sensitive. The limits of detection of OLME, AMLO and HCTZ were determined 0.19, 0.16 and 0.22 µg/mL and limits of quantification of OLME, AMLO and HCTZ were determined 0.57, 0.49 and 0.66, respectively. Forced degradation study was performed according to International Conference on Harmonization guidelines.

Evaluation of Small Mass Spectrometer Systems

NASA Technical Reports Server (NTRS)

Arkin, C. Richard; Griffin, Timothy P.; Ottens, Andrew K.; Diaz, Jorge A.; Follistein, Duke W.; Adams, Fredrick W.; Helms, William R.; Voska, N. (Technical Monitor)

2002-01-01

This work is aimed at understanding the aspects of designing a miniature mass spectrometer (MS) system. A multitude of commercial and government sectors, such as the military, environmental agencies and industrial manufacturers of semiconductors, refrigerants, and petroleum products, would find a small, portable, rugged and reliable MS system beneficial. Several types of small MS systems are evaluated and discussed, including linear quadrupole, quadrupole ion trap, time of flight and sector. The performance of each system in terms of accuracy, precision, limits of detection, response time, recovery time, scan rate, volume and weight is assessed. A performance scale is setup to rank each systems and an overall performance score is given to each system. All experiments involved the analysis of hydrogen, helium, oxygen and argon in a nitrogen background with the concentrations of the components of interest ranging from 0-5000 part-per-million (ppm). The relative accuracies of the systems vary from < 1% to approx. 40% with an average below 10%. Relative precisions varied from 1% to 20%, with an average below 5%. The detection limits had a large distribution, ranging from 0.2 to 170 ppm. The systems had a diverse response time ranging from 4 s to 210 s as did the recovery time with a 6 s to 210 s distribution. Most instruments had scan times near, 1 s, however one instrument exceeded 13 s. System weights varied from 9 to 52 kg and sizes from 15 x 10(exp 3)cu cm to 110 x 10(exp 3) cu cm.

Combination of corona discharge ion mobility spectrometry with a novel reagent gas and two immiscible organic solvent liquid-liquid-liquid microextraction for analysis of clomipramine in biological samples.

PubMed

Saraji, Mohammad; Bidgoli, Ali Akbar Hajialiakbari; Khayamian, Taghi; Moradmand, Ali

2011-12-02

A novel and sensitive method based on combination of two immiscible organic solvents hollow fiber-based liquid-liquid-liquid microextraction and corona discharge ion mobility spectrometry (HF-LLLME-CD-IMS) was employed for the analysis of clomipramine in human urine and plasma. The effect of formic, acetic and propionic acid as the reagent gas (dopant) on the corona discharge ion mobility signal was investigated. The influence of dopant amount was also studied. Optimum mass flow rates of the dopants were 3.7, 1.1 and 1.0 μmol min(-1) for formic, acetic and propionic acid, respectively. Experimental parameters influencing the extraction efficiency of HF-LLLME, such as NaOH concentration as donor solution, ionic strength of the sample, stirring rate, and extraction time were investigated and optimized. Under the optimum conditions, analytical parameters such as linearity, precision and limit of detection were also evaluated. The linear dynamic range was from 1 to 100 μg L(-1) (r(2)=0.9980) and the limit of detection was 0.35 μg L(-1). Intra- and inter-day precisions were satisfactory with a relative standard deviation (RSD) of 5.9 and 6.7%, respectively. The proposed method was satisfactorily applied for the determination of clomipramine in human plasma and urine. Copyright © 2011 Elsevier B.V. All rights reserved.

QbD-Based Development and Validation of a Stability-Indicating HPLC Method for Estimating Ketoprofen in Bulk Drug and Proniosomal Vesicular System.

PubMed

Yadav, Nand K; Raghuvanshi, Ashish; Sharma, Gajanand; Beg, Sarwar; Katare, Om P; Nanda, Sanju

2016-03-01

The current studies entail systematic quality by design (QbD)-based development of simple, precise, cost-effective and stability-indicating high-performance liquid chromatography method for estimation of ketoprofen. Analytical target profile was defined and critical analytical attributes (CAAs) were selected. Chromatographic separation was accomplished with an isocratic, reversed-phase chromatography using C-18 column, pH 6.8, phosphate buffer-methanol (50 : 50v/v) as a mobile phase at a flow rate of 1.0 mL/min and UV detection at 258 nm. Systematic optimization of chromatographic method was performed using central composite design by evaluating theoretical plates and peak tailing as the CAAs. The method was validated as per International Conference on Harmonization guidelines with parameters such as high sensitivity, specificity of the method with linearity ranging between 0.05 and 250 µg/mL, detection limit of 0.025 µg/mL and quantification limit of 0.05 µg/mL. Precision was demonstrated using relative standard deviation of 1.21%. Stress degradation studies performed using acid, base, peroxide, thermal and photolytic methods helped in identifying the degradation products in the proniosome delivery systems. The results successfully demonstrated the utility of QbD for optimizing the chromatographic conditions for developing highly sensitive liquid chromatographic method for ketoprofen. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simultaneous determination of six active components by a single standard to determine multicomponents combined with fingerprint analysis for the quality control of Rhizoma Chuanxiong.

PubMed

He, Yufei; Li, Qing; Bi, Kaishun

2015-04-01

To control the quality of Rhizoma Chuanxiong, a method based on high-performance liquid chromatography method coupled with diode array detection was developed for the quantitative analysis of six active ingredients using a single standard to determine multi-components and chemical fingerprint analysis for the first time. The separation was performed on an Agilent Zorbax SB-C18 column by gradient elution with methanol and aqueous phase (containing 0.5% glacial acetic acid) at a flow rate of 1.0 mL/min. The UV wavelength was set at 274 nm. This assay was fully validated with respect to precision, repeatability, and accuracy. All calibration curves showed good linearity (R(2) > 0.9994) within test ranges. The limit of detection and limit of quantification were lower than 0.01 and 0.03 μg/mL, respectively. The relative standard deviation for repeatability and the intermediate precision of six analytes were less than 1.6 and 2.5%, respectively, the overall recovery was 96.1-103.1%. In addition, fingerprint chromatography using hierarchical clustering analysis and similarity analysis was performed to differentiate and classify the samples. The method described here could provide a more comprehensive and reasonable scientific assessment of the quality of Rhizoma Chuanxiong. Therefore, the strategy is feasible, credible, and is easily and effectively adapted for evaluating the quality control of Rhizoma Chuanxiong. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensorimotor responsiveness and resolution in the giraffe.

PubMed

More, Heather L; O'Connor, Shawn M; Brøndum, Emil; Wang, Tobias; Bertelsen, Mads F; Grøndahl, Carsten; Kastberg, Karin; Hørlyck, Arne; Funder, Jonas; Donelan, J Maxwell

2013-03-15

The ability of an animal to detect and respond to changes in the environment is crucial to its survival. However, two elements of sensorimotor control - the time required to respond to a stimulus (responsiveness) and the precision of stimulus detection and response production (resolution) - are inherently limited by a competition for space in peripheral nerves and muscles. These limitations only become more acute as animal size increases. In this paper, we investigated whether the physiology of giraffes has found unique solutions for maintaining sensorimotor performance in order to compensate for their extreme size. To examine responsiveness, we quantified three major sources of delay: nerve conduction delay, muscle electromechanical delay and force generation delay. To examine resolution, we quantified the number and size distribution of nerve fibers in the sciatic nerve. Rather than possessing a particularly unique sensorimotor system, we found that our measurements in giraffes were broadly comparable to size-dependent trends seen across other terrestrial mammals. Consequently, both giraffes and other large animals must contend with greater sensorimotor delays and lower innervation density in comparison to smaller animals. Because of their unconventional leg length, giraffes may experience even longer delays compared with other animals of the same mass when sensing distal stimuli. While there are certainly advantages to being tall, there appear to be challenges as well - our results suggest that giraffes are less able to precisely and accurately sense and respond to stimuli using feedback alone, particularly when moving quickly.

Determination of acetanilide herbicides in cereal crops using accelerated solvent extraction, solid-phase extraction and gas chromatography-electron capture detector.

PubMed

Zhang, Yaping; Yang, Jun; Shi, Ronghua; Su, Qingde; Yao, Li; Li, Panpan

2011-07-01

A method was developed to determine eight acetanilide herbicides from cereal crops based on accelerated solvent extraction (ASE) and solid-phase extraction (SPE) followed by gas chromatography-electron capture detector (GC-ECD) analysis. During the ASE process, the effect of four parameters (temperature, static time, static cycles and solvent) on the extraction efficiency was considered and compared with shake-flask extraction method. After extraction with ASE, four SPE tubes (graphitic carbon black/primary secondary amine (GCB/PSA), GCB, Florisil and alumina-N) were assayed for comparison to obtain the best clean-up efficiency. The results show that GCB/PSA cartridge gave the best recoveries and cleanest chromatograms. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, limit of detection (LOD), limit of quantitation (LOQ), precision and recovery were studied. At 0.05 mg/kg spiked level, recoveries and precision values for rice, wheat and maize were 82.3-115.8 and 1.1-13.6%, respectively. For all the herbicides, LOD and LOQ ranged from 0.8 to 1.7 μg/kg and from 2.4 to 5.3 μg/kg, respectively. The proposed analytical methodology was applied for the analysis of the targets in samples; only three herbicides, propyzamid, metolachlor and diflufenican, were detected in two samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Designing Successful Next-Generation Instruments to Detect the Epoch of Reionization

NASA Astrophysics Data System (ADS)

Thyagarajan, Nithyanandan; Hydrogen Epoch of Reionization Array (HERA) team, Murchison Widefield Array (MWA) team

2018-01-01

The Epoch of Reionization (EoR) signifies a period of intense evolution of the Inter-Galactic Medium (IGM) in the early Universe caused by the first generations of stars and galaxies, wherein they turned the neutral IGM to be completely ionized by redshift ≥ 6. This important epoch is poorly explored to date. Measurement of redshifted 21 cm line from neutral Hydrogen during the EoR is promising to provide the most direct constraints of this epoch. Ongoing experiments to detect redshifted 21 cm power spectrum during reionization, including the Murchison Widefield Array (MWA), Precision Array for Probing the Epoch of Reionization (PAPER), and the Low Frequency Array (LOFAR), appear to be severely affected by bright foregrounds and unaccounted instrumental systematics. For example, the spectral structure introduced by wide-field effects, aperture shapes and angular power patterns of the antennas, electrical and geometrical reflections in the antennas and electrical paths, and antenna position errors can be major limiting factors. These mimic the 21 cm signal and severely degrade the instrument performance. It is imperative for the next-generation of experiments to eliminate these systematics at their source via robust instrument design. I will discuss a generic framework to set cosmologically motivated antenna performance specifications and design strategies using the Precision Radio Interferometry Simulator (PRISim) -- a high-precision tool that I have developed for simulations of foregrounds and the instrument transfer function intended primarily for 21 cm EoR studies, but also broadly applicable to interferometer-based intensity mapping experiments. The Hydrogen Epoch of Reionization Array (HERA), designed in-part based on this framework, is expected to detect the 21 cm signal with high significance. I will present this framework and the simulations, and their potential for designing upcoming radio instruments such as HERA and the Square Kilometre Array (SKA).

Metabolism of levamisole and kinetics of levamisole and aminorex in urine by means of LC-QTOF-HRMS and LC-QqQ-MS.

PubMed

Hess, Cornelius; Ritke, Natalie; Broecker, Sebastian; Madea, Burkhard; Musshoff, Frank

2013-05-01

The antihelminthic drug Levamisole can enhance cocaine effects by conversion into the amphetamine-like drug aminorex. We describe an LC-MS method for the determination of levamisole and its metabolite aminorex in human urine. Selectivity is given, calibration curves were linear within the calibration range 2.5-250 ng/mL; limits of the method were LoD 0.51 ng/mL, LoQ 1.02 ng/mL for levamisole and LoD 0.65 ng/mL, LoQ 0.76 ng/mL for aminorex. Precision data was in accordance with the guidelines (intraday precision for aminorex ranged between 5.75 and 11.0 % for levamisole between 8.36 and 10.9 %; interday precision for levamisole 10.9-16.9 % and for aminorex 7.64-12.7 %; accuracy data for levamisole -1.96 to -14.3 % and for aminorex-11.9 to-18.5 %). The validated method was successfully applied to study the urinary excretion of levamisole after the administration of 100 mg of levamisole orally. Levamisole and aminorex could be detected in post-administration urine samples. Levamisole could be detected up to 39 h after ingestion, while aminorex was detectable up to 54 h. Maximum aminorex concentrations were 45 ng/mL urine. Further metabolites of levamisole after oral ingestion by means of liquid chromatography hybrid quadrupole time-of-flight high-resolution mass spectrometry (LC-QTOF-HRMS) were identified. Only 0.5 % of the ingested drug was quantified as unchanged levamisole in urine. Besides aminorex, five isomers of aminorex and 4 hydroxy-metabolites of aminorex or its isomers were found. Furthermore, levamisole is also hydroxylated and eliminated free or conjugated with sulfate or glucuronide into urine.

Digital PCR: A Sensitive and Precise Method for KIT D816V Quantification in Mastocytosis.

PubMed

Greiner, Georg; Gurbisz, Michael; Ratzinger, Franz; Witzeneder, Nadine; Simonitsch-Klupp, Ingrid; Mitterbauer-Hohendanner, Gerlinde; Mayerhofer, Matthias; Müllauer, Leonhard; Sperr, Wolfgang R; Valent, Peter; Hoermann, Gregor

2018-03-01

The analytically sensitive detection of KIT D816V in blood and bone marrow is important for diagnosing systemic mastocytosis (SM). Additionally, precise quantification of the KIT D816V variant allele fraction (VAF) is relevant clinically because it helps to predict multilineage involvement and prognosis in cases of advanced SM. Digital PCR (dPCR) is a promising new method for sensitive detection and accurate quantification of somatic mutations. We performed a validation study of dPCR for KIT D816V on 302 peripheral blood and bone marrow samples from 156 patients with mastocytosis for comparison with melting curve analysis after peptide nucleic acid-mediated PCR clamping (clamp-PCR) and allele-specific quantitative real-time PCR (qPCR). dPCR showed a limit of detection of 0.01% VAF with a mean CV of 8.5% and identified the mutation in 90% of patients compared with 70% for clamp-PCR ( P < 0.001). Moreover, dPCR for KIT D816V was highly concordant with qPCR without systematic deviation of results, and confirmed the clinical value of KIT D816V VAF measurements. Thus, patients with advanced SM showed a significantly higher KIT D816V VAF (median, 2.43%) compared with patients with indolent SM (median, 0.14%; P < 0.001). Moreover, dPCR confirmed the prognostic significance of a high KIT D816V VAF regarding survival ( P < 0.001). dPCR for KIT D816V provides a high degree of precision and sensitivity combined with the potential for interlaboratory standardization, which is crucial for the implementation of KIT D816V allele burden measurement. Thus, dPCR is suitable as a new method for KIT D816V testing in patients with mastocytosis. © 2017 American Association for Clinical Chemistry.

FPGA-Based X-Ray Detection and Measurement for an X-Ray Polarimeter

NASA Technical Reports Server (NTRS)

Gregory, Kyle; Hill, Joanne; Black, Kevin; Baumgartner, Wayne

2013-01-01

This technology enables detection and measurement of x-rays in an x-ray polarimeter using a field-programmable gate array (FPGA). The technology was developed for the Gravitational and Extreme Magnetism Small Explorer (GEMS) mission. It performs precision energy and timing measurements, as well as rejection of non-x-ray events. It enables the GEMS polarimeter to detect precisely when an event has taken place so that additional measurements can be made. The technology also enables this function to be performed in an FPGA using limited resources so that mass and power can be minimized while reliability for a space application is maximized and precise real-time operation is achieved. This design requires a low-noise, charge-sensitive preamplifier; a highspeed analog to digital converter (ADC); and an x-ray detector with a cathode terminal. It functions by computing a sum of differences for time-samples whose difference exceeds a programmable threshold. A state machine advances through states as a programmable number of consecutive samples exceeds or fails to exceed this threshold. The pulse height is recorded as the accumulated sum. The track length is also measured based on the time from the start to the end of accumulation. For track lengths longer than a certain length, the algorithm estimates the barycenter of charge deposit by comparing the accumulator value at the midpoint to the final accumulator value. The design also employs a number of techniques for rejecting background events. This innovation enables the function to be performed in space where it can operate autonomously with a rapid response time. This implementation combines advantages of computing system-based approaches with those of pure analog approaches. The result is an implementation that is highly reliable, performs in real-time, rejects background events, and consumes minimal power.

Sub-ppb, Autonomous, Real-time Detection of VOCs with iCRDS

NASA Astrophysics Data System (ADS)

Leen, J.; Gupta, M.; Baer, D. S.

2013-12-01

The continuous, real-time detection of sub-parts-per-billion (ppb) concentrations of volatile organic compounds (VOCs) such as trichloroethylene (TCE) and tetrachloroethylene (PCE) remains difficult, time consuming and expensive. In particular, short term exposure spikes and diurnal variations are difficult or impossible to detect with traditional TO-15 measurements. We present laboratory and field performance data from an instrument based on incoherent cavity ringdown spectroscopy (iCRDS) that operates in the mid-infrared (bands from 860-1060 cm-1 or 970-1280 cm-1) and is capable of detecting a broad range of VOCs, in situ, continuously and autonomously. We have demonstrated the measurement of TCE in zero air with a precision of 0.17 ppb (1σ in 4 minutes). PCE was measured with a precision of 0.15 ppb (1σ in 4 minutes). Both of these measured precisions exceed the EPA's commercial building action limit, which for TCE is 0.92 ppb (5 μg/m3) and for PCE is 0.29 ppb (2 μg/m3). Additionally, the instrument is capable of precisely measuring and quantifying BTEX compounds (benzene, toluene, ethylbenzene, xylene), including differentiation of xylene isomers. We have demonstrated the accurate, interference free measurement of Mountain View, California air doped with TCE concentrations ranging from 4.22 ppb (22.8 μg/m3) to 17.74 ppb (96 μg/m3) with a precision of 1.42 ppb (1σ in 4 minutes). Mountain View, California air doped with 10.83 ppb of PCE (74.0 μg/m3) was measured with a precision of 0.54 ppb (1σ in 4 minutes). Finally, the instrument was deployed to the Superfund site at Moffett Naval Air Station in Mountain View, California where contaminated ground water results in vapor intrusion of TCE and PCE. For two weeks, the instrument operated continuously and autonomously, successfully measuring TCE and PCE concentrations in both the breathing zone and steam tunnel air. TCE concentrations in the breathing zone averaged 0.186 × 0.669 ppb while tunnel air averaged 17.38 × 4.96 ppb, in excellent agreement with previous TO-15 8 hr averages. PCE concentrations in the breathing zone averaged 0.063 × 0.270 ppb while tunnel air averaged 0.755 × 0.359 ppb, again, in excellent agreement with previous TO-15 8 hr averages. The iCRDS instrument has shown the ability to continuously and autonomously measure sub-ppb levels of toxic VOCs in the field, offering an unprecedented picture of the short term dynamics associated with vapor intrusion and ground water pollution.

Comparison of ultraviolet detection and charged aerosol detection methods for liquid-chromatographic determination of protoescigenin.

PubMed

Filip, Katarzyna; Grynkiewicz, Grzegorz; Gruza, Mariusz; Jatczak, Kamil; Zagrodzki, Bogdan

2014-01-01

Escin, a complex mixture of pentacyclic triterpene saponins obtained from horse chestnut seeds extract (HCSE; Aesculus hippocastanum L.), constitutes a traditional herbal active substance of preparations (drugs) used for a treatment of chronic venous insufficiency and capillary blood vessel leakage. A new approach to exploitation of pharmacological potential of this saponin complex has been recently proposed, in which the β-escin mixture is perceived as a source of a hitherto unavailable raw material, pentacyclic triterpene aglycone-protoescigenin. Although many liquid chromatography methods are described in the literature for saponins determination, analysis of protoescigenin is barely mentioned. In this work, a new ultra-high performance liquid chromatography (UHPLC) method developed for protoescigenin quantification has been described. CAD (charged aerosol detection), as a relatively new detection method based on aerosol charging, has been applied in this method as an alternative to ultraviolet (UV) detection. The influence of individual parameters on CAD response and sensitivity was studied. The detection was performed using CAD and UV (200 nm) simultaneously and the results were compared with reference to linearity, accuracy, precision and limit of detection.

Scent Lure Effect on Camera-Trap Based Leopard Density Estimates

PubMed Central

Braczkowski, Alexander Richard; Balme, Guy Andrew; Dickman, Amy; Fattebert, Julien; Johnson, Paul; Dickerson, Tristan; Macdonald, David Whyte; Hunter, Luke

2016-01-01

Density estimates for large carnivores derived from camera surveys often have wide confidence intervals due to low detection rates. Such estimates are of limited value to authorities, which require precise population estimates to inform conservation strategies. Using lures can potentially increase detection, improving the precision of estimates. However, by altering the spatio-temporal patterning of individuals across the camera array, lures may violate closure, a fundamental assumption of capture-recapture. Here, we test the effect of scent lures on the precision and veracity of density estimates derived from camera-trap surveys of a protected African leopard population. We undertook two surveys (a ‘control’ and ‘treatment’ survey) on Phinda Game Reserve, South Africa. Survey design remained consistent except a scent lure was applied at camera-trap stations during the treatment survey. Lures did not affect the maximum movement distances (p = 0.96) or temporal activity of female (p = 0.12) or male leopards (p = 0.79), and the assumption of geographic closure was met for both surveys (p >0.05). The numbers of photographic captures were also similar for control and treatment surveys (p = 0.90). Accordingly, density estimates were comparable between surveys (although estimates derived using non-spatial methods (7.28–9.28 leopards/100km2) were considerably higher than estimates from spatially-explicit methods (3.40–3.65 leopards/100km2). The precision of estimates from the control and treatment surveys, were also comparable and this applied to both non-spatial and spatial methods of estimation. Our findings suggest that at least in the context of leopard research in productive habitats, the use of lures is not warranted. PMID:27050816

Laser ablation inductively coupled plasma mass spectrometry for direct isotope ratio measurements on solid samples

NASA Astrophysics Data System (ADS)

Pickhardt, Carola; Dietze, Hans-Joachim; Becker, J. Sabine

2005-04-01

Isotope ratio measurements have been increasingly used in quite different application fields, e.g., for the investigation of isotope variation in nature, in geoscience (geochemistry and geochronology), in cosmochemistry and planetary science, in environmental science, e.g., in environmental monitoring, or by the application of the isotope dilution technique for quantification purposes using stable or radioactive high-enriched isotope tracers. Due to its high sensitivity, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is today a challenging mass spectrometric technique for the direct determination of precise and accurate isotope ratios in solid samples. In comparison to laser ablation quadrupole ICP-MS (LA-ICP-QMS), laser ablation coupled to a double-focusing sector field ICP-MS (LA-ICP-SFMS) with single ion detection offers a significant improvement of sensitivity at low mass resolution, whereby isotope ratios can be measured with a precision to 0.1% relative standard deviation (R.S.D.). In LA-ICP-SFMS, many disturbing isobaric interferences of analyte and molecular ions can be separated at the required mass resolution (e.g., 40Ar16O+ and 56Fe+ for iron isotope ratio measurements). The precision on isotope ratio measurements was improved by one order of magnitude via the simultaneous detection of mass-separated ion currents of isotopes using multiple ion collectors in LA-ICP-MS (LA-MC-ICP-MS). The paper discusses the state of the art, the challenges and limits in isotope ratio measurements by LA-ICP-MS using different instrumentations at the trace and ultratrace level in different fields of application as in environmental and biological research, geochemistry and geochronology with respect to their precision and accuracy.

Determination of Tinopal CBS-X in rice papers and rice noodles using HPLC with fluorescence detection and LC-MS/MS.

PubMed

Ko, Kyung Yuk; Lee, Chae A; Choi, Jae Chon; Kim, Meehye

2014-01-01

To date there have been no reports of methods to determine Tinopal CBS-X. We developed a rapid and simple method to determine the Tinopal CBS-X content in rice noodles and rice papers using HPLC equipped with fluorescence detection. Heating the rice noodles and rice papers to 80°C after adding 75% methanol solution induced the release of Tinopal CBS-X from processed rice products. Tinopal CBS-X was separated using an isocratic mobile phase comprising 50% acetonitrile/water containing 0.4% tetrabutyl ammonium hydrogen sulphate at pH 8.0. The samples suspected to be positive by HPLC analysis were then confirmed by LC-MS/MS analysis. This study also investigated the Tinopal CBS-X content of three rice noodle products and two rice papers. The limits of quantification for rice papers and rice noodles were 1.58 and 1.51 µg kg(-1), respectively, and their correlation curves showed good linearity with r(2) ≥ 0.9997 and ≥ 0.9998, respectively. Moreover, rice papers had recoveries of 70.3-83.3% with precision ranging from 5.0% to 7.9%, whereas rice noodles had slightly lower recoveries of 63.4-78.7% and precisions of 8.5-11.5%. Only one rice noodle product contained Tinopal CBS-X, at around 2.1 mg kg(-1), whereas it was not detected in four other samples. Consequently, Tinopal CBS-X from rice noodles and rice papers can be successfully detected using the developed pre-treatment and ion-pairing HPLC system coupled with fluorescence detection.

Detection of new VOC compounds with iCRDS

NASA Astrophysics Data System (ADS)

Huang, H.; Leen, J. B.; Gardner, A.; Gupta, M.; Baer, D. S.

2015-12-01

The instrument at Los Gatos Research (a member of ABB Inc.) which is based on incoherent cavity ringdown spectroscopy (iCRDS) that operates in the mid-infrared (bands from 860-1060 cm-1 or 970-1280 cm-1) is capable of detecting a broad range of VOCs, in situ, continuously and autonomously, for example, BTEX compounds (benzene, toluene, ethylbenzene, xylene), including differentiation of xylene isomers. Previously, we have demonstrated the measurement of trichloroethylene (TCE) in zero air with a precision of 0.17 ppb (1σ in 4 minutes), and the measurement of tetrachloroethylene (PCE) with a precision of 0.15 ppb (1σ in 4 minutes). Both of these measured precisions exceed the EPA's commercial building action limit, which for TCE is 0.92 ppb (5 µg/m3) and for PCE is 0.29 ppb (2 µg/m3). This ability has been fully demonstrated by the deployment of the instrument to the Superfund site at Moffett Naval Air Station in Mountain View, California where contaminated ground water results in vapor intrusion of TCE and PCE. For two weeks, the instrument operated continuously and autonomously, successfully measuring TCE and PCE concentrations in both the breathing zone and steam tunnel air, in excellent agreement with previous TO-15 data. In this poster, we present laboratory performance data targeting new toxic molecules with the same instrument. We have demonstrated the measurement of trichlorofluolomethane (Freon 11) in zero air with a precision of 1 ppb (3σ at 1075cm-1), and hexafluoropropene in zero air with a precision of about 0.3 ppb (3σ per spectrum). The iCRDS instrument has shown the ability to continuously and autonomously measure sub-ppb levels of toxic VOCs in the lab/field, offering an unprecedented picture of the short term dynamics associated with vapor intrusion and ground water pollution.

The Gaia Astrometric Survey of Nearby M Dwarfs: A Treasure Trove for Exoplanet Astrophysics

NASA Astrophysics Data System (ADS)

Sozzetti, Alessandro; Giacobbe, P.; Lattanzi, M. G.; Micela, G.; Tinetti, G.

2011-09-01

Cool, nearby M dwarfs within a few tens of parsecs from the Sun are becoming the focus of dedicated experiments in the realm of exoplanets astrophysics. This is due to the shift in theoretical paradigms in light of new observations, and to the improved understanding of the observational opportunities for planet detection and characterization provided by this sample. Gaia, in its all-sky survey, will deliver precision astrometry for a magnitude-limited (V=20) sample of M dwarfs, providing an inventory of cool nearby stars with a much higher degree of completeness (particularly for late sub-types) with respect to currently available catalogs. We gauge the Gaia potential for precision astrometry of exoplanets orbiting a sample of already known dM stars within 30 pc from the Sun, carefully selected based on cross-correlation among catalogs in the literature (e.g., Lepine, PMSU). We express Gaia sensitivity thresholds as a function of system parameters and in view of the latest mission profile, including the most up-to-date astrometric error model. The simulations also provide insight on the capability of high-precision astrometry to reconstruct the underlying orbital elements and mass distributions of the generated companions. These results will help in evaluating the complete expected Gaia planet population around late-type stars. We investigate the synergy between the Gaia data on nearby M dwarfs and other ground-based and space-borne programs for planet detection and characterization, with a particular focus on: a) the improvements in the determination of transiting planet parameters thanks to the exquisitely precise stellar distances determined by Gaia; b) the betterment in orbit modeling when Gaia astrometry and precision radial-velocities are available for the same targets; and c) the ability of Gaia to carefully predict the ephemerides of (transiting and non-transiting) planets around M stars, for spectroscopic characterization of their atmospheres with dedicated observatories in space, such as EChO.

High Performance Thin layer Chromatography: Densitometry Method for Determination of Rubraxanthone in the Stem Bark Extract of Garcinia cowa Roxb.

PubMed

Hamidi, Dachriyanus; Aulia, Hilyatul; Susanti, Meri

2017-01-01

Garcinia cowa is a medicinal plant widely grown in Southeast Asia and tropical countries. Various parts of this plant have been used in traditional folk medicine. The bark, latex, and root have been used as an antipyretic agent, while fruit and leaves have been used as an expectorant, for indigestion and improvement of blood circulation. This study aims to determine the concentration of rubraxanthone found in ethyl acetate extract of the stem bark of G. cowa by the high-performance thin-layer chromatography (HPTLC). HPTLC method was performed on precoated silica gel G 60 F254 plates using an HPTLC system with a developed mobile-phase system of chloroform: ethyl acetate: methanol: formic acid (86:6:3:5). A volume of 5 μL of standard and sample solutions was applied to the chromatographic plates. The plates were developed in saturated mode of twin trough chamber at room temperature. The method was validated based on linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and specificity. The spots were observed at ultraviolet 243 nm. The linearity of rubraxanthone was obtained between 52.5 and 157.5 ppm/spot. The LOD and LOQ were found to be 4.03 and 13.42 ppm/spot, respectively. The proposed method showed good linearity, precision, accuracy, and high sensitivity. Therefore, it may be applied for the quantification of rubraxanthone in ethyl acetate extract of the stem bark of G. cowa . High performance thin layer chromatography (HPTLC) method provides rapid qualitative and quantitative estimation of rubraxanthone as a marker com¬pound in G. cowa extract used for commercial productRubraxanthone found in ethyl acetate extracts of G. cowa was successfully quantified using HPTLC method. Abbreviations Used : TLC: Thin-layer chromatography, HPTLC: High-performance thin-layer chromatography, LOD: Limit of detection, LOQ: Limit of quantification, ICH: International Conference on Harmonization.

Simultaneous determination of four 5-hydroxy polymethoxyflavones by reversed-phase high performance liquid chromatography with electrochemical detection.

PubMed

Dong, Ping; Qiu, Peiju; Zhu, Yi; Li, Shiming; Ho, Chi-Tang; McClements, David Julian; Xiao, Hang

2010-01-29

Accumulating evidence has suggested the potential health-promoting effects of 5-hydroxy polymethoxyflavones (5-OH-PMFs) naturally existing in citrus genus. However, research efforts are hampered by the lack of reliable and sensitive methods for their determination in plant materials and biological samples. Using reversed-phase high performance liquid chromatography (HPLC) equipped with electrochemical (EC) detection, we have developed a fast and highly sensitive method for quantification of four 5-OH-PMFs, namely 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, 5-hydroxy-6,7,4'-trimethoxyflavone, and 5-hydroxy-6,7,8,4'-tetramethoxyflavone. The method was fully validated in terms of linearity, accuracy and precision. The limit of detection (LOD) was determined as being between 0.65 and 1.8ng/mL (ppb), demonstrating an over 160 times higher sensitivity in comparison with the previously reported method using UV detection. The recovery rate of the method was between 96.17% and 110.82%, and the precision for the retention times and peak areas was all below 13%. The method was successfully used to quantify 5-OH-PMFs with a wide range of abundance in the citrus products and preparations, such as orange juice, citrus peel, and dried tangerine peel. The quantification method for 5-OH-PMFs developed herein could be useful for the nutritional and pharmacological studies of these compounds in future. Copyright (c) 2009 Elsevier B.V. All rights reserved.

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography.

PubMed

Shim, You-Shin; Yoon, Won-Jin; Kim, Dong-Man; Watanabe, Masaki; Park, Hyun-Jin; Jang, Hae Won; Lee, Jangho; Ha, Jaeho

2015-01-01

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography (UHPLC) coupled with the heating-block acidic hydrolysis method was validated through the precision, accuracy and linearity. The UHPLC separation was performed on a reversed-phase C18 column (particle size 2 μm, i.d. 2 mm, length 100 mm) with a photodiode-array detector. The limits of detection and quantification of the UHPLC analyses were 0.09 and 0.29 mg/kg for delphinidin, 0.08 and 0.24 mg/kg for cyanidin, 0.09 and 0.26 mg/kg for petunidin, 0.14 and 0.42 mg/kg for pelargonidin, 0.16 and 0.48 mg/kg for peonidin and 0.30 and 0.91 mg/kg for malvidin, respectively. The intra- and inter-day precisions of individual anthocyanidin aglycones were <10.3%. All calibration curves exhibited good linearity (r = 0.999) within the tested ranges. The total run time of UHPLC was 8 min. The simple preparation method with UHPLC detection in this study presented herein significantly improved the speed and the simplicity for preparation step of delphinidin, cyanidin, petunidin, pelargonidin, peonidin and malvidin in fruits. Especially, the UHPLC detection exhibited good resolution in spite of shorter run time about four times than conventional HPLC detection. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Query-by-example surgical activity detection.

PubMed

Gao, Yixin; Vedula, S Swaroop; Lee, Gyusung I; Lee, Mija R; Khudanpur, Sanjeev; Hager, Gregory D

2016-06-01

Easy acquisition of surgical data opens many opportunities to automate skill evaluation and teaching. Current technology to search tool motion data for surgical activity segments of interest is limited by the need for manual pre-processing, which can be prohibitive at scale. We developed a content-based information retrieval method, query-by-example (QBE), to automatically detect activity segments within surgical data recordings of long duration that match a query. The example segment of interest (query) and the surgical data recording (target trial) are time series of kinematics. Our approach includes an unsupervised feature learning module using a stacked denoising autoencoder (SDAE), two scoring modules based on asymmetric subsequence dynamic time warping (AS-DTW) and template matching, respectively, and a detection module. A distance matrix of the query against the trial is computed using the SDAE features, followed by AS-DTW combined with template scoring, to generate a ranked list of candidate subsequences (substrings). To evaluate the quality of the ranked list against the ground-truth, thresholding conventional DTW distances and bipartite matching are applied. We computed the recall, precision, F1-score, and a Jaccard index-based score on three experimental setups. We evaluated our QBE method using a suture throw maneuver as the query, on two tool motion datasets (JIGSAWS and MISTIC-SL) captured in a training laboratory. We observed a recall of 93, 90 and 87 % and a precision of 93, 91, and 88 % with same surgeon same trial (SSST), same surgeon different trial (SSDT) and different surgeon (DS) experiment setups on JIGSAWS, and a recall of 87, 81 and 75 % and a precision of 72, 61, and 53 % with SSST, SSDT and DS experiment setups on MISTIC-SL, respectively. We developed a novel, content-based information retrieval method to automatically detect multiple instances of an activity within long surgical recordings. Our method demonstrated adequate recall across different complexity datasets and experimental conditions.

Location precision analysis of stereo thermal anti-sniper detection system

NASA Astrophysics Data System (ADS)

He, Yuqing; Lu, Ya; Zhang, Xiaoyan; Jin, Weiqi

2012-06-01

Anti-sniper detection devices are the urgent requirement in modern warfare. The precision of the anti-sniper detection system is especially important. This paper discusses the location precision analysis of the anti-sniper detection system based on the dual-thermal imaging system. It mainly discusses the following two aspects which produce the error: the digital quantitative effects of the camera; effect of estimating the coordinate of bullet trajectory according to the infrared images in the process of image matching. The formula of the error analysis is deduced according to the method of stereovision model and digital quantitative effects of the camera. From this, we can get the relationship of the detecting accuracy corresponding to the system's parameters. The analysis in this paper provides the theory basis for the error compensation algorithms which are put forward to improve the accuracy of 3D reconstruction of the bullet trajectory in the anti-sniper detection devices.

Gravimetric Analysis of Particulate Matter using Air Samplers Housing Internal Filtration Capsules.

PubMed

O'Connor, Sean; O'Connor, Paula Fey; Feng, H Amy; Ashley, Kevin

2014-10-01

An evaluation was carried out to investigate the suitability of polyvinyl chloride (PVC) internal capsules, housed within air sampling devices, for gravimetric analysis of airborne particles collected in workplaces. Experiments were carried out using blank PVC capsules and PVC capsules spiked with 0,1 - 4 mg of National Institute of Standards and Technology Standard Reference Material ® (NIST SRM) 1648 (Urban Particulate Matter) and Arizona Road Dust (Air Cleaner Test Dust). The capsules were housed within plastic closed-face cassette samplers (CFCs). A method detection limit (MDL) of 0,075 mg per sample was estimated. Precision S r at 0,5 - 4 mg per sample was 0,031 and the estimated bias was 0,058. Weight stability over 28 days was verified for both blanks and spiked capsules. Independent laboratory testing on blanks and field samples verified long-term weight stability as well as sampling and analysis precision and bias estimates. An overall precision estimate Ŝ rt of 0,059 was obtained. An accuracy measure of ±15,5% was found for the gravimetric method using PVC internal capsules.

Gravimetric Analysis of Particulate Matter using Air Samplers Housing Internal Filtration Capsules

PubMed Central

O'Connor, Sean; O'Connor, Paula Fey; Feng, H. Amy

2015-01-01

Summary An evaluation was carried out to investigate the suitability of polyvinyl chloride (PVC) internal capsules, housed within air sampling devices, for gravimetric analysis of airborne particles collected in workplaces. Experiments were carried out using blank PVC capsules and PVC capsules spiked with 0,1 – 4 mg of National Institute of Standards and Technology Standard Reference Material® (NIST SRM) 1648 (Urban Particulate Matter) and Arizona Road Dust (Air Cleaner Test Dust). The capsules were housed within plastic closed-face cassette samplers (CFCs). A method detection limit (MDL) of 0,075 mg per sample was estimated. Precision Sr at 0,5 - 4 mg per sample was 0,031 and the estimated bias was 0,058. Weight stability over 28 days was verified for both blanks and spiked capsules. Independent laboratory testing on blanks and field samples verified long-term weight stability as well as sampling and analysis precision and bias estimates. An overall precision estimate Ŝrt of 0,059 was obtained. An accuracy measure of ±15,5% was found for the gravimetric method using PVC internal capsules. PMID:26435581

HADES RV Programme with HARPS-N at TNG. II. Data treatment and simulations

NASA Astrophysics Data System (ADS)

Perger, M.; García-Piquer, A.; Ribas, I.; Morales, J. C.; Affer, L.; Micela, G.; Damasso, M.; Suárez-Mascareño, A.; González-Hernández, J. I.; Rebolo, R.; Herrero, E.; Rosich, A.; Lafarga, M.; Bignamini, A.; Sozzetti, A.; Claudi, R.; Cosentino, R.; Molinari, E.; Maldonado, J.; Maggio, A.; Lanza, A. F.; Poretti, E.; Pagano, I.; Desidera, S.; Gratton, R.; Piotto, G.; Bonomo, A. S.; Martinez Fiorenzano, A. F.; Giacobbe, P.; Malavolta, L.; Nascimbeni, V.; Rainer, M.; Scandariato, G.

2017-02-01

Context. The distribution of exoplanets around low-mass stars is still not well understood. Such stars, however, present an excellent opportunity for reaching down to the rocky and habitable planet domains. The number of current detections used for statistical purposes remains relatively modest and different surveys, using both photometry and precise radial velocities, are searching for planets around M dwarfs. Aims: Our HARPS-N red dwarf exoplanet survey is aimed at the detection of new planets around a sample of 78 selected stars, together with the subsequent characterization of their activity properties. Here we investigate the survey performance and strategy. Methods: From 2700 observed spectra, we compare the radial velocity determinations of the HARPS-N DRS pipeline and the HARPS-TERRA code, calculate the mean activity jitter level, evaluate the planet detection expectations, and address the general question of how to define the strategy of spectroscopic surveys in order to be most efficient in the detection of planets. Results: We find that the HARPS-TERRA radial velocities show less scatter and we calculate a mean activity jitter of 2.3 m s-1 for our sample. For a general radial velocity survey with limited observing time, the number of observations per star is key for the detection efficiency. In the case of an early M-type target sample, we conclude that approximately 50 observations per star with exposure times of 900 s and precisions of approximately 1 ms-1 maximizes the number of planet detections. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC).

Using SPOT-5 images in rice farming for detecting BPH (Brown Plant Hopper)

NASA Astrophysics Data System (ADS)

Ghobadifar, F.; Wayayok, A.; Shattri, M.; Shafri, H.

2014-06-01

Infestation of rice plant-hopper such as Brown Plant Hopper (BPH) (Nilaparvata lugens) is one of the most notable risk in rice yield in tropical areas especially in Asia. In order to use visible and infrared images to detect stress in rice production caused by BPH infestation, several remote sensing techniques have been developed. Initial recognition of pest infestation by means of remote sensing will spreads, for precision farming practice. To address this issue, detection of sheath blight in rice farming was examined by using SPOT-5 images. Specific image indices such as Normalized decrease food production costs, limit environmental hazards, and enhance natural pest control before the problem Normalized Difference Vegetation Index (NDVI), Standard difference indices (SDI) and Ratio Vegetation Index (RVI) were used for analyses using ENVI 4.8 and SPSS software. Results showed that all the indices to recognize infected plants are significant at α = 0.01. Examination of the association between the disease indices indicated that band 3 (near infrared) and band 4 (mid infrared) have a relatively high correlation. The selected indices declared better association for detecting healthy plants from diseased ones. Consequently, these sorts of indices especially NDVI could be valued as indicators for developing techniques for detecting the sheath blight of rice by using remote sensing. This infers that they are useful for crop disease detection but the spectral resolution is probably not sufficient to distinguish plants with light infections (low severity level). Using the index as an indicator can clarify the threshold for zoning the outbreaks. Quick assessment information is very useful in precision farming to practice site specific management such as pesticide application.

A sensitive and selective liquid chromatography/tandem mass spectrometry method for quantitative analysis of efavirenz in human plasma.

PubMed

Srivastava, Praveen; Moorthy, Ganesh S; Gross, Robert; Barrett, Jeffrey S

2013-01-01

A selective and a highly sensitive method for the determination of the non-nucleoside reverse transcriptase inhibitor (NNRTI), efavirenz, in human plasma has been developed and fully validated based on high performance liquid chromatography tandem mass spectrometry (LC-MS/MS). Sample preparation involved protein precipitation followed by one to one dilution with water. The analyte, efavirenz was separated by high performance liquid chromatography and detected with tandem mass spectrometry in negative ionization mode with multiple reaction monitoring. Efavirenz and ¹³C₆-efavirenz (Internal Standard), respectively, were detected via the following MRM transitions: m/z 314.20243.90 and m/z 320.20249.90. A gradient program was used to elute the analytes using 0.1% formic acid in water and 0.1% formic acid in acetonitrile as mobile phase solvents, at a flow-rate of 0.3 mL/min. The total run time was 5 min and the retention times for the internal standard (¹³C₆-efavirenz) and efavirenz was approximately 2.6 min. The calibration curves showed linearity (coefficient of regression, r>0.99) over the concentration range of 1.0-2,500 ng/mL. The intraday precision based on the standard deviation of replicates of lower limit of quantification (LLOQ) was 9.24% and for quality control (QC) samples ranged from 2.41% to 6.42% and with accuracy from 112% and 100-111% for LLOQ and QC samples. The inter day precision was 12.3% and 3.03-9.18% for LLOQ and quality controls samples, and the accuracy was 108% and 95.2-108% for LLOQ and QC samples. Stability studies showed that efavirenz was stable during the expected conditions for sample preparation and storage. The lower limit of quantification for efavirenz was 1 ng/mL. The analytical method showed excellent sensitivity, precision, and accuracy. This method is robust and is being successfully applied for therapeutic drug monitoring and pharmacokinetic studies in HIV-infected patients.

Complexity in estimation of esomeprazole and its related impurities' stability in various stress conditions in low-dose aspirin and esomeprazole magnesium capsules.

PubMed

Reddy, Palavai Sripal; Hotha, Kishore Kumar; Sait, Shakil

2013-01-01

A complex, sensitive, and precise high-performance liquid chromatographic method for the profiling of impurities of esomeprazole in low-dose aspirin and esomeprazole capsules has been developed, validated, and used for the determination of impurities in pharmaceutical products. Esomeprazole and its related impurities' development in the presence of aspirin was traditionally difficult due to aspirin's sensitivity to basic conditions and esomeprazole's sensitivity to acidic conditions. When aspirin is under basic, humid, and extreme temperature conditions, it produces salicylic acid and acetic acid moieties. These two byproducts create an acidic environment for the esomeprazole. Due to the volatility and migration phenomenon of the produced acetic acid and salicylic acid from aspirin in the capsule dosage form, esomeprazole's purity, stability, and quantification are affected. The objective of the present research work was to develop a gradient reversed-phase liquid chromatographic method to separate all the degradation products and process-related impurities from the main peak. The impurities were well-separated on a RP8 column (150 mm × 4.6mm, X-terra, RP8, 3.5μm) by the gradient program using a glycine buffer (0.08 M, pH adjusted to 9.0 with 50% NaOH), acetonitrile, and methanol at a flow rate of 1.0 mL min(-1) with detection wavelength at 305 nm and column temperature at 30°C. The developed method was found to be specific, precise, linear, accurate, rugged, and robust. LOQ values for all of the known impurities were below reporting thresholds. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation in the presence of aspirin. The developed RP-HPLC method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, ruggedness, and robustness.

Development of a Stability-Indicating Stereoselective Method for Quantification of the Enantiomer in the Drug Substance and Pharmaceutical Dosage Form of Rosuvastatin Calcium by an Enhanced Approach

PubMed Central

Rajendra Reddy, Gangireddy; Ravindra Reddy, Papammagari; Siva Jyothi, Polisetty

2015-01-01

A novel, simple, precise, and stability-indicating stereoselective method was developed and validated for the accurate quantification of the enantiomer in the drug substance and pharmaceutical dosage forms of Rosuvastatin Calcium. The method is capable of quantifying the enantiomer in the presence of other related substances. The chromatographic separation was achieved with an immobilized cellulose stationary phase (Chiralpak IB) 250 mm x 4.6 mm x 5.0 μm particle size column with a mobile phase containing a mixture of n-hexane, dichloromethane, 2-propanol, and trifluoroacetic acid in the ratio 82:10:8:0.2 (v/v/v/v). The eluted compounds were monitored at 243 nm and the run time was 18 min. Multivariate analysis and statistical tools were used to develop this highly robust method in a short span of time. The stability-indicating power of the method was established by subjecting Rosuvastatin Calcium to the stress conditions (forced degradation) of acid, base, oxidative, thermal, humidity, and photolytic degradation. Major degradation products were identified and found to be well-resolved from the enantiomer peak, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection and limit of quantification, precision, linearity, accuracy, and robustness. The method exhibited consistent, high-quality recoveries (100 ± 10%) with a high precision for the enantiomer. Linear regression analysis revealed an excellent correlation between the peak responses and concentrations (r2 value of 0.9977) for the enantiomer. The method is sensitive enough to quantify the enantiomer above 0.04% and detect the enantiomer above 0.015% in Rosuvastatin Calcium. The stability tests were also performed on the drug substances as per ICH norms. PMID:26839815

Statistical precision of the intensities retrieved from constrained fitting of overlapping peaks in high-resolution mass spectra

DOE PAGES

Cubison, M. J.; Jimenez, J. L.

2015-06-05

Least-squares fitting of overlapping peaks is often needed to separately quantify ions in high-resolution mass spectrometer data. A statistical simulation approach is used to assess the statistical precision of the retrieved peak intensities. The sensitivity of the fitted peak intensities to statistical noise due to ion counting is probed for synthetic data systems consisting of two overlapping ion peaks whose positions are pre-defined and fixed in the fitting procedure. The fitted intensities are sensitive to imperfections in the m/Q calibration. These propagate as a limiting precision in the fitted intensities that may greatly exceed the precision arising from counting statistics.more » The precision on the fitted peak intensity falls into one of three regimes. In the "counting-limited regime" (regime I), above a peak separation χ ~ 2 to 3 half-widths at half-maximum (HWHM), the intensity precision is similar to that due to counting error for an isolated ion. For smaller χ and higher ion counts (~ 1000 and higher), the intensity precision rapidly degrades as the peak separation is reduced ("calibration-limited regime", regime II). Alternatively for χ < 1.6 but lower ion counts (e.g. 10–100) the intensity precision is dominated by the additional ion count noise from the overlapping ion and is not affected by the imprecision in the m/Q calibration ("overlapping-limited regime", regime III). The transition between the counting and m/Q calibration-limited regimes is shown to be weakly dependent on resolving power and data spacing and can thus be approximated by a simple parameterisation based only on peak intensity ratios and separation. A simple equation can be used to find potentially problematic ion pairs when evaluating results from fitted spectra containing many ions. Longer integration times can improve the precision in regimes I and III, but a given ion pair can only be moved out of regime II through increased spectrometer resolving power. As a result, studies presenting data obtained from least-squares fitting procedures applied to mass spectral peaks should explicitly consider these limits on statistical precision.« less

Simplified RP-HPLC method for multi-residue analysis of abamectin, emamectin benzoate and ivermectin in rice.

PubMed

Xie, Xianchuan; Gong, Shu; Wang, Xiaorong; Wu, Yinxing; Zhao, Li

2011-01-01

A rapid, reliable and sensitive reverse-phase high-performance liquid chromatography method with fluorescence detection (RP-FLD-HPLC) was developed and validated for simultaneous analysis of the abamectin (ABA), emamectin (EMA) benzoate and ivermectin (IVM) residues in rice. After extraction with acetonitrile/water (2 : 1) with sonication, the avermectin (AVMs) residues were directly derivatised by N-methylimidazole (N-NMIM) and trifluoroacetic anhydride (TFAA) and then analysed on RP-FLD-HPLC. A good linear relationship (r(2 )> 0.99) was obtained for three AVMs ranging from 0.01 to 5 microg ml(-1), i.e. 0.01-5.0 microg g(-1) in rice matrix. The limit of detection (LOD) and the limit of quantification (LOQ) were between 0.001 and 0.002 microg g(-1) and between 0.004 and 0.006 microg g(-1), respectively. Recoveries were from 81.9% to 105.4% and precision less than 12.4%. The proposed method was successfully applied to routine analysis of the AVMs residues in rice.

Establishment of a method for determination of arsenic species in seafood by LC-ICP-MS.

PubMed

Zmozinski, Ariane V; Llorente-Mirandes, Toni; López-Sánchez, José F; da Silva, Márcia M

2015-04-15

An analytical method for determination of arsenic species (inorganic arsenic (iAs), methylarsonic acid (MA), dimethylarsinic acid (DMA), arsenobetaine (AB), trimethylarsine oxide (TMAO) and arsenocholine (AC)) in Brazilian and Spanish seafood samples is reported. This study was focused on extraction and quantification of inorganic arsenic (iAs), the most toxic form. Arsenic speciation was carried out via LC with both anionic and cationic exchange with ICP-MS detection (LC-ICP-MS). The detection limits (LODs), quantification limits (LOQs), precision and accuracy for arsenic species were established. The proposed method was evaluated using eight reference materials (RMs). Arsenobetaine was the main species found in all samples. The total and iAs concentration in 22 seafood samples and RMs ranged between 0.27-35.2 and 0.02-0.71 mg As kg(-1), respectively. Recoveries ranging from 100% to 106% for iAs, based on spikes, were achieved. The proposed method provides reliable iAs data for future risk assessment analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development and validation of an MEKC method for determination of nitrogen-containing drugs in pharmaceutical preparations.

PubMed

Buiarelli, Francesca; Coccioli, Franco; Jasionowska, Renata; Terracciano, Alessandro

2008-09-01

A fast and accurate micellar electrokinetic capillary chromatography method was developed for quality control of pharmaceutical preparations containing cold remedies as acetaminophen, salicylamide, caffeine, phenylephrine, pseudoephedrine, norephedrine and chlorpheniramine. The method optimization was realized on a Beckman P/ACE System MDQ instrument. The baseline separation of seven analytes was performed in an uncoated fused silica capillary internal diameter (ID)=50 microm using tris-borate (20 mM, pH=8.5) containing sodium dodecyl sulphate 30 mM BGE. On line-UV detection at 214 nm was performed and the applied voltage was 10 kV. The operating temperature was 25 degrees C. After experimental conditions optimization, the proposed method was validated. The evaluated parameters were: precision of migration time and of corrected peak area ratio, linearity range, limit of detection, limit of quantification, accuracy (recovery), ruggedness and applicability. The method was then successfully applied for the analysis of three pharmaceutical preparations containing some of the analytes listed before.

Direct detection constraints on dark photon dark matter

NASA Astrophysics Data System (ADS)

An, Haipeng; Pospelov, Maxim; Pradler, Josef; Ritz, Adam

2015-07-01

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01- 100 keV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to O (10-15), assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity to dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. We also revisit indirect constraints from V → 3 γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ-ray flux.

Determination of Residual Solvents in Linezolid by Static Headspace GC

PubMed Central

Feng, Xiao-Zhen; Han, Guo-Cheng; Qin, Jianhe; Yin, Shi-min; Chen, Zhencheng

2016-01-01

A headspace gas chromatographic method was developed for the determination of residual solvents in linezolid active substances. The solvents include petroleum ether (60–90°C), acetone, tetrahydrofuran, ethyl acetate, methanol, dichloromethane (DCM) and pyridine. The method showed the possibility to detect the tested solvents with a linear determination correlation coefficient (r) greater than 0.9995 except for petroleum ether (0.9980). The limits of detection ranged between 0.12 μg/mL (petroleum ether) and 3.56 μg/mL (DCM), and the limits of quantity ranged between 0.41 μg/mL (petroleum ether) and 11.86 μg/mL (DCM). The method achieved good accuracy (recoveries ranging from 92.8 to 102.5%) and precision for both run-to-run and day-to-day assay (relative standard deviation ranging from 0.4 to 1.3%) for all seven solvents concerned, which were applied in the quality control of three batches of linezolid successfully. PMID:26657409

Precursor ion scan driven fast untargeted screening and semi-determination of caffeoylquinic acid derivatives in Cynara scolymus L.

PubMed

Shen, Qing; Lu, Yanbin; Dai, Zhiyuan; Cheung, Hon-Yeung

2015-01-01

A precursor ion scan (PIS) technique based strategy was developed for rapid screening and semi-determination of caffeoylquinic acid derivatives (CADs) in artichoke (Cynara scolymus L.) using ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry. 1,5-Dicaffeoylquinic acid and 5-caffeoylquinic acid were used for studying the fragmentation behaviour of two classes of CADs, setting m/z 191 as a diagnostic moiety. When it was applied to artichoke sample, ten CADs were detected and elucidated in a single PIS run. Furthermore, method validation was implemented including: specificity (no interference), linearity (≥0.9993), limit of detection (LOD<0.12 ng mL(-1)) and limit of quantification (LOQ<0.25 ng mL(-1)), precision (RSD≤3.6), recovery (91.4-95.9%) and stability (at least 12 h). This approach was proven to be a powerful, selective and sensitive tool for rapid screening and semi-determination of untargeted components in natural products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development and analytical performance evaluation of FREND-SAA and FREND-Hp

NASA Astrophysics Data System (ADS)

Choi, Eunha; Seong, Jihyun; Lee, Seiyoung; Han, Sunmi

2017-07-01

The FREND System is a portable cartridge reader, quantifying analytes by measuring laser-induced fluorescence in a single-use reagent cartridge. The objective of this study was to evaluate FREND-SAA and FREND-Hp assays. The FREND-SAA and Hp assays were standardized to the WHO and IFCC reference materials. Analytical performance studies of Precision, Linearity, Limits of Detections, Interferences, and Method Comparisons for both assays were performed according to the CLSI guidelines. Both assays demonstrated acceptable imprecision of %CV in three different levels of samples. The linearity of the assays was found to be acceptable (SAA 5 150 mg/L, Hp 30 400 mg/dL). The detection limits were 3.8 mg/L (SAA) and 10.2 mg/dL (Hp). No significant interference and no significant deviation from linearity was found in the both comparison studies. In conclusion, NanoEnTek's FREND-SAA and Hp assays represent rapid, accurate and convenient means to quantify SAA and Hp in human serum on FREND system.

Simultaneous HPTLC Determination of Rabeprazole and Itopride Hydrochloride From Their Combined Dosage Form.

PubMed

Suganthi, A; John, Sofiya; Ravi, T K

2008-01-01

A simple, precise, sensitive, rapid and reproducible HPTLC method for the simultaneous estimation of the rabeprazole and itopride hydrochloride in tablets was developed and validated. This method involves separation of the components by TLC on precoated silica gel G60F254 plate with solvent system of n-butanol, toluene and ammonia (8.5:0.5:1 v/v/v) and detection was carried out densitometrically using a UV detector at 288 nm in absorbance mode. This system was found to give compact spots for rabeprazole (Rf value of 0.23 0.02) and for itopride hydrochloride (Rf value of 0.75+/-0.02). Linearity was found to be in the range of 40-200 ng/spot and 300-1500 ng/spot for rabeprazole and itopride hydrochloride. The limit of detection and limit of quantification for rabeprazole were 10 and 20 ng/spot and for itopride hydrochloride were 50 and 100 ng/spot, respectively. The method was found to be beneficial for the routine analysis of combined dosage form.

Method of analysis at the U.S. Geological Survey California Water Science Center, Sacramento Laboratory - determination of haloacetic acid formation potential, method validation, and quality-control practices

USGS Publications Warehouse

Zazzi, Barbara C.; Crepeau, Kathryn L.; Fram, Miranda S.; Bergamaschi, Brian A.

2005-01-01

An analytical method for the determination of haloacetic acid formation potential of water samples has been developed by the U.S. Geological Survey California Water Science Center Sacramento Laboratory. The haloacetic acid formation potential is measured by dosing water samples with chlorine under specified conditions of pH, temperature, incubation time, darkness, and residual-free chlorine. The haloacetic acids formed are bromochloroacetic acid, bromodichloroacetic acid, dibromochloroacetic acid, dibromoacetic acid, dichloroacetic acid, monobromoacetic acid, monochloroacetic acid, tribromoacetic acid, and trichloroacetic acid. They are extracted, methylated, and then analyzed using a gas chromatograph equipped with an electron capture detector. Method validation experiments were performed to determine the method accuracy, precision, and detection limit for each of the compounds. Method detection limits for these nine haloacetic acids ranged from 0.11 to 0.45 microgram per liter. Quality-control practices include the use of blanks, quality-control samples, calibration verification standards, surrogate recovery, internal standard, matrix spikes, and duplicates.

Direct detection constraints on dark photon dark matter

DOE PAGES

An, Haipeng; Pospelov, Maxim; Pradler, Josef; ...

2015-06-11

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01–100KeV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to Ο(10 –15), assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity tomore » dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. As a result, we also revisit indirect constraints from V → 3γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ-ray flux.« less

On Detecting New Worlds: The Art of Doppler Spectroscopy with Iodine Cells

NASA Astrophysics Data System (ADS)

Wang, Sharon Xuesong

2016-08-01

The first discovery of an extra-solar planet (exoplanet) around a main-sequence star, 51 Peg b, discovered using Doppler spectroscopy, opened up the field of exoplanets. For more than a decade, the dominant way for finding exoplanets was using precise Doppler spectroscopy to measure the radial velocity (RV) changes of stars. Today, precise Doppler spectroscopy is still crucial for the discovery and characterization of exoplanets, and it has a great chance for finding the first rocky exoplanet in the Habitable Zone of its host star. However, such endeavor requires an exquisite precision of 10-50 cm/s while the current state of the art is 1 m/s. This thesis set out to improve the RV precision of two precise Doppler spectrometers on two 10-meter class telescopes: HET/HRS and Keck/HIRES. Both of these spectrometers use iodine cells as their wavelength calibration sources, and their spectral data are being analyzed via forward modeling to estimate stellar RVs. Neither HET/HRS or Keck/HIRES deliver an RV precision at the photon-limited level, meaning that there are additional RV systematic errors caused by instrumental changes or errors in the data analysis. HET/HRS has an RV precision of 3-5 m/s, while Keck/HIRES has about 1-2 m/s. I have found that the leading cause behind HET/HRS's "under-performance" in comparison to Keck/HIRES is temperature changes of the iodine gas cell (and thus an inaccurate iodine reference spectrum). Another reason is the insufficient modeling of the HET/HRS instrumental profile. While Keck/HIRES does not suffer from these problems, it also has several RV systematic error sources of con siderable sizes. The work in this thesis has revealed that the errors in Keck/HIRES's stellar reference spectrum add about 1 m/s to the error budget and are the major drivers behind the spurious RV signal at the period of a sidereal year and its harmonics. Telluric contamination and errors caused by the spectral fitting algorithm also contribute on the level of 20-50 cm/s. The strategies proposed and tested in this thesis will improve the RV precision of HET/HRS and Keck/HIRES, including their decade worth of archival data. This thesis also documents my work on characterizing exoplanet orbits using RV data and the discovery of HD 37605c. It concludes with a summary of major findings and an outline of future plans to use future precise Doppler spectrometers to move towards the goal of 10 cm/s and detecting Earth 2.0.

Dual linear structured support vector machine tracking method via scale correlation filter

NASA Astrophysics Data System (ADS)

Li, Weisheng; Chen, Yanquan; Xiao, Bin; Feng, Chen

2018-01-01

Adaptive tracking-by-detection methods based on structured support vector machine (SVM) performed well on recent visual tracking benchmarks. However, these methods did not adopt an effective strategy of object scale estimation, which limits the overall tracking performance. We present a tracking method based on a dual linear structured support vector machine (DLSSVM) with a discriminative scale correlation filter. The collaborative tracker comprised of a DLSSVM model and a scale correlation filter obtains good results in tracking target position and scale estimation. The fast Fourier transform is applied for detection. Extensive experiments show that our tracking approach outperforms many popular top-ranking trackers. On a benchmark including 100 challenging video sequences, the average precision of the proposed method is 82.8%.

Balancing precision and risk: should multiple detection methods be analyzed separately in N-mixture models?

USGS Publications Warehouse

Graves, Tabitha A.; Royle, J. Andrew; Kendall, Katherine C.; Beier, Paul; Stetz, Jeffrey B.; Macleod, Amy C.

2012-01-01

Using multiple detection methods can increase the number, kind, and distribution of individuals sampled, which may increase accuracy and precision and reduce cost of population abundance estimates. However, when variables influencing abundance are of interest, if individuals detected via different methods are influenced by the landscape differently, separate analysis of multiple detection methods may be more appropriate. We evaluated the effects of combining two detection methods on the identification of variables important to local abundance using detections of grizzly bears with hair traps (systematic) and bear rubs (opportunistic). We used hierarchical abundance models (N-mixture models) with separate model components for each detection method. If both methods sample the same population, the use of either data set alone should (1) lead to the selection of the same variables as important and (2) provide similar estimates of relative local abundance. We hypothesized that the inclusion of 2 detection methods versus either method alone should (3) yield more support for variables identified in single method analyses (i.e. fewer variables and models with greater weight), and (4) improve precision of covariate estimates for variables selected in both separate and combined analyses because sample size is larger. As expected, joint analysis of both methods increased precision as well as certainty in variable and model selection. However, the single-method analyses identified different variables and the resulting predicted abundances had different spatial distributions. We recommend comparing single-method and jointly modeled results to identify the presence of individual heterogeneity between detection methods in N-mixture models, along with consideration of detection probabilities, correlations among variables, and tolerance to risk of failing to identify variables important to a subset of the population. The benefits of increased precision should be weighed against those risks. The analysis framework presented here will be useful for other species exhibiting heterogeneity by detection method.

Application of 1013 ohm Faraday cup current amplifiers for boron isotopic analyses by solution mode and laser ablation multicollector inductively coupled plasma mass spectrometry.

PubMed

Lloyd, Nicholas S; Sadekov, Aleksey Yu; Misra, Sambuddha

2018-01-15

Boron isotope ratios (δ 11 B values) are used as a proxy for seawater paleo-pH, amongst several other applications. The analytical precision can be limited by the detection of low intensity ion beams from limited sample amounts. High-gain amplifiers offer improvements in signal/noise ratio and can be used to increase measurement precision and reduce sample amounts. 10 13 ohm amplifier technology has previously been applied to several radiogenic systems, but has thus far not been applied to non-traditional stable isotopes. Here we apply 10 13 ohm amplifier technology for the measurement of boron isotope ratios using solution mode MC-ICP-MS and laser ablation mode (LA-)MC-ICP-MS techniques. Precision is shown for reference materials as well as for low-volume foraminifera samples. The baseline uncertainty for a 0.1 pA 10 B + ion beam is reduced to <0.1 ‰ for a typical measurement period. The external precision is better than 0.2 ‰ (2SD) for δ 11 B measurements for solution samples containing as little as 0.8 ng total boron. For in situ microanalyses with LA-MC-ICP-MS, the external precision of 11 B/ 10 B from an in-house calcite standard was 1 ‰ (2SD) for individual spot analyses, and 0.3 ‰ for the mean of ≥10 replicate spot analyses. 10 13 ohm amplifier technology is demonstrated to offer advantages for the determination of δ 11 B values by both MC-ICP-MS and LA-MC-ICP-MS for small samples of biogenic carbonates, such as foraminifera shells. 10 13 ohm amplifier technology will also be of benefit to other non-traditional stable isotope measurements. Copyright © 2017 John Wiley & Sons, Ltd.

Quantitative determination of trigonelline in mouse serum by means of hydrophilic interaction liquid chromatography-MS/MS analysis: Application to a pharmacokinetic study.

PubMed

Szczesny, Damian; Bartosińska, Ewa; Jacyna, Julia; Patejko, Małgorzata; Siluk, Danuta; Kaliszan, Roman

2018-02-01

Trigonelline is a pyridine alkaloid found in fenugreek seeds and coffee beans. Most of the previous studies are concerned with the quantification of trigonelline along with other constituents in coffee herbs or beverages. Only a few have focused on its determination in animal or human tissues by applying different modes of HPLC with UV or MS detection. The aim of the study was to develop and validate a fast and simple method for trigonelline determination in serum by the use of hydrophilic interaction liquid chromatography (HILIC) with ESI-MS/MS detection. Separation of trigonelline was achieved on a Kinetex HILIC column operated at 35°C with acetonitrile-ammonium formate (10 mm, pH = 3) buffer mixture (55:45, v/v) as the mobile phase. The developed method was successfully applied to determine trigonelline concentration in mouse serum after intravenous administration of 10 mg/kg. The developed assay is sensitive (limit of detection = 1.5 ng/mL, limit of quantification = 5.0 ng/mL) and linear in a concentration range from 5.0 to 250.0 ng/mL. Sample preparation is limited to deproteinization, centrifugation and filtration. The application of the HILIC mode of chromatography with MS detection and selection of deuterated trigonelline as internal standard allowed a rapid and precise method of trigonelline quantification to be to developed. Copyright © 2017 John Wiley & Sons, Ltd.

Combining simplicity with cost-effectiveness: Investigation of potential counterfeit of proton pump inhibitors through simulated formulations using thin-layer chromatography.

PubMed

Bhatt, Nejal M; Chavada, Vijay D; Sanyal, Mallika; Shrivastav, Pranav S

2016-11-18

A simple, accurate and precise high-performance thin-layer chromatographic method has been developed and validated for the analysis of proton pump inhibitors (PPIs) and their co-formulated drugs, available as binary combination. Planar chromatographic separation was achieved using a single mobile phase comprising of toluene: iso-propranol: acetone: ammonia 5.0:2.3:2.5:0.2 (v/v/v/v) for the analysis of 14 analytes on aluminium-backed layer of silica gel 60 FG 254 . Densitometric determination of the separated spots was done at 290nm. The method was validated according to ICH guidelines for linearity, precision and accuracy, sensitivity, specificity and robustness. The method showed good linear response for the selected drugs as indicated by the high values of correlation coefficients (≥0.9993). The limit of detection and limit of quantiation were in the range of 6.9-159.2ng/band and 20.8-478.1ng/band respectively for all the analytes. The optimized conditions afforded adequate resolution of each PPI from their co-formulated drugs and provided unambiguous identification of the co-formulated drugs from their homologous retardation factors (hR f ). The only limitation of the method was the inability to separate two PPIs, rabeprazole and lansoprazole from each other. Nevertheless, it is proposed that peak spectra recording and comparison with standard drug spot can be a viable option for assignment of TLC spots. The method performance was assessed by analyzing different laboratory simulated mixtures and some marketed formulations of the selected drugs. The developed method was successfully used to investigate potential counterfeit of PPIs through a series of simulated formulations with good accuracy and precision. Copyright © 2016 Elsevier B.V. All rights reserved.

Measuring changes in Plasmodium falciparum transmission: Precision, accuracy and costs of metrics

PubMed Central

Tusting, Lucy S.; Bousema, Teun; Smith, David L.; Drakeley, Chris

2016-01-01

As malaria declines in parts of Africa and elsewhere, and as more countries move towards elimination, it is necessary to robustly evaluate the effect of interventions and control programmes on malaria transmission. To help guide the appropriate design of trials to evaluate transmission-reducing interventions, we review eleven metrics of malaria transmission, discussing their accuracy, precision, collection methods and costs, and presenting an overall critique. We also review the non-linear scaling relationships between five metrics of malaria transmission; the entomological inoculation rate, force of infection, sporozoite rate, parasite rate and the basic reproductive number, R0. Our review highlights that while the entomological inoculation rate is widely considered the gold standard metric of malaria transmission and may be necessary for measuring changes in transmission in highly endemic areas, it has limited precision and accuracy and more standardised methods for its collection are required. In areas of low transmission, parasite rate, sero-conversion rates and molecular metrics including MOI and mFOI may be most appropriate. When assessing a specific intervention, the most relevant effects will be detected by examining the metrics most directly affected by that intervention. Future work should aim to better quantify the precision and accuracy of malaria metrics and to improve methods for their collection. PMID:24480314

Accuracy or precision: Implications of sample design and methodology on abundance estimation

USGS Publications Warehouse

Kowalewski, Lucas K.; Chizinski, Christopher J.; Powell, Larkin A.; Pope, Kevin L.; Pegg, Mark A.

2015-01-01

Sampling by spatially replicated counts (point-count) is an increasingly popular method of estimating population size of organisms. Challenges exist when sampling by point-count method, and it is often impractical to sample entire area of interest and impossible to detect every individual present. Ecologists encounter logistical limitations that force them to sample either few large-sample units or many small sample-units, introducing biases to sample counts. We generated a computer environment and simulated sampling scenarios to test the role of number of samples, sample unit area, number of organisms, and distribution of organisms in the estimation of population sizes using N-mixture models. Many sample units of small area provided estimates that were consistently closer to true abundance than sample scenarios with few sample units of large area. However, sample scenarios with few sample units of large area provided more precise abundance estimates than abundance estimates derived from sample scenarios with many sample units of small area. It is important to consider accuracy and precision of abundance estimates during the sample design process with study goals and objectives fully recognized, although and with consequence, consideration of accuracy and precision of abundance estimates is often an afterthought that occurs during the data analysis process.

Object detection in cinematographic video sequences for automatic indexing

NASA Astrophysics Data System (ADS)

Stauder, Jurgen; Chupeau, Bertrand; Oisel, Lionel

2003-06-01

This paper presents an object detection framework applied to cinematographic post-processing of video sequences. Post-processing is done after production and before editing. At the beginning of each shot of a video, a slate (also called clapperboard) is shown. The slate contains notably an electronic audio timecode that is necessary for audio-visual synchronization. This paper presents an object detection framework to detect slates in video sequences for automatic indexing and post-processing. It is based on five steps. The first two steps aim to reduce drastically the video data to be analyzed. They ensure high recall rate but have low precision. The first step detects images at the beginning of a shot possibly showing up a slate while the second step searches in these images for candidates regions with color distribution similar to slates. The objective is to not miss any slate while eliminating long parts of video without slate appearance. The third and fourth steps are statistical classification and pattern matching to detected and precisely locate slates in candidate regions. These steps ensure high recall rate and high precision. The objective is to detect slates with very little false alarms to minimize interactive corrections. In a last step, electronic timecodes are read from slates to automize audio-visual synchronization. The presented slate detector has a recall rate of 89% and a precision of 97,5%. By temporal integration, much more than 89% of shots in dailies are detected. By timecode coherence analysis, the precision can be raised too. Issues for future work are to accelerate the system to be faster than real-time and to extend the framework for several slate types.

A Search for Transiting Neptune-Mass Extrasolar Planets in High-Precision Photometry of Solar-Type Stars

NASA Technical Reports Server (NTRS)

Henry, Stephen M.; Gillman, Amelie r.; Henry, Gregory W.

2005-01-01

Tennessee State University operates several automatic photometric telescopes (APTs) at Fairborn Observatory in southern Arizona. Four 0.8 m APTs have been dedicated to measuring subtle luminosity variations that accompany magnetic cycles in solar-type stars. Over 1000 program and comparison stars have been observed every clear night in this program for up to 12 years with a precision of approximately 0.0015 mag for a single observation. We have developed a transit-search algorithm, based on fitting a computed transit template for each trial period, and have used it to search our photometric database for transits of unknown companions. Extensive simulations with the APT data have shown that we can reliably recover transits with periods under 10 days as long as the transits have a depth of at least 0.0024 mag, or about 1.6 times the scatter in the photometric observations. Thus, due to our high photometric precision, we are sensitive to transits of possible short-period Neptune-mass planets that likely would have escaped detection by current radial velocity techniques. Our search of the APT data sets for 1087 program and comparison stars revealed no new transiting planets. However, the detection of several unknown grazing eclipsing binaries from among our comparison stars, with eclipse depths of only a few millimags, illustrates the success of our technique. We have used this negative result to place limits on the frequency of Neptune-mass planets in close orbits around solar-type stars in the Sun's vicinity.

A Miniaturized On-Chip Colorimeter for Detecting NPK Elements

PubMed Central

Liu, Rui-Tao; Tao, Lu-Qi; Liu, Bo; Tian, Xiang-Guang; Mohammad, Mohammad Ali; Yang, Yi; Ren, Tian-Ling

2016-01-01

Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source–microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications. PMID:27527177

A Miniaturized On-Chip Colorimeter for Detecting NPK Elements.

PubMed

Liu, Rui-Tao; Tao, Lu-Qi; Liu, Bo; Tian, Xiang-Guang; Mohammad, Mohammad Ali; Yang, Yi; Ren, Tian-Ling

2016-08-04

Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source-microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications.

Nonlethal evaluation of the physiological health of unionid mussels: Method for biopsy and glycogen analysis

USGS Publications Warehouse

Naimo, T.J.; Damschen, E.D.; Rada, R.G.; Monroe, E.M.

1998-01-01

In long-lived unionid mussels, many short-term measures of growth are of limited value. Changes in physiological condition may be an early indication of stress, because the increased energy demand associated with stress often results in a depletion of glycogen reserves, the principal storage form of carbohydrates in unionid mussels. Our goal was to nonlethally extract tissue from freshwater mussels and then to develop a rapid and dependable method for the analysis of glycogen in the tissue extracts. A biopsy technique was developed to remove between 5 and 10 mg of food tissue in Amblema plicata plicata. The survival rate did not differ between biopsied and non-biopsied mussels during a 581-d observation period, demonstrating that the biopsy technique will allow nonlethal evaluation of the physiological condition of individual mussels through measurement of changes in contaminant, genetic, and biochemical indicators in tissue. We also modified the standard alkaline digestion and phenol-sulfuric acid analysis of glycogen for use on the small samples of biopsied tissue and to reduce analysis time and cost. We present quality control data, including method detection limits and estimates of precision and bias. The modified analytical method is rapid and accurate and has a method detection limit of 0.014 mg glycogen. Glycogen content in the biopsied samples was well above the method detection limit; it ranged from 0.09 to 0.36 mg, indicating that the method should be applicable to native mussels.

Highly Sensitive Detection of UV Radiation Using a Uranium Coordination Polymer.

PubMed

Liu, Wei; Dai, Xing; Xie, Jian; Silver, Mark A; Zhang, Duo; Wang, Yanlong; Cai, Yawen; Diwu, Juan; Wang, Jian; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-02-07

The accurate detection of UV radiation is required in a wide range of chemical industries and environmental or biological related applications. Conventional methods taking advantage of semiconductor photodetectors suffer from several drawbacks such as sophisticated synthesis and manufacturing procedure, not being able to measure the accumulated UV dosage as well as high defect density in the material. Searching for new strategies or materials serving as precise UV dosage sensor with extremely low detection limit is still highly desirable. In this work, a radiation resistant uranium coordination polymer [UO 2 (L)(DMF)] (L = 5-nitroisophthalic acid, DMF = N,N-dimethylformamide, denoted as compound 1) was successfully synthesized through mild solvothermal method and investigated as a unique UV probe with the detection limit of 2.4 × 10 -7 J. On the basis of the UV dosage dependent luminescence spectra, EPR analysis, single crystal structure investigation, and the DFT calculation, the UV-induced radical quenching mechanism was confirmed. Importantly, the generated radicals are of significant stability which offers the opportunity for measuring the accumulated UV radiation dosage. Furthermore, the powder material of compound 1 was further upgraded into membrane material without loss in luminescence intensity to investigate the real application potentials. To the best of our knowledge, compound 1 represents the most sensitive coordination polymer based UV dosage probe reported to date.

[High throuput analysis of organophosphorus pesticide residues and their metabolites in animal original foods by dual gas chromatography-dual pulse flame photometric detection].

PubMed

Yang, Lixin; Li, Heli; Miao, Hong; Zeng, Fangang; Li, Ruifeng; Chen, Huijing; Zhao, Yunfeng; Wu, Yongning

2011-10-01

A method was established for the quantitative determination of 54 organophosphorus pesticide residues and their metabolites in foods of animal origin by dual gas chromatography-dual pulse flame photometric detection. Homogenized samples were extracted with acetone and methylene chloride, and cleaned-up by gel permeation chromatography (GPC). The response of each analyte showed a good linearity with a correlation coefficient not less than 0. 99. The recovery experiments were performed by a blank sample spiked at low, medium and high fortification levels. The recoveries for beef, mutton, pork, chicken were in the range of 50. 5% -128. 1% with the relative standard deviations (n = 6) of 1. 1% -25. 5%, which demonstrated the good precision and accuracy of the present method. The limits of detection for the analytes were in the range of 0. 001 -0. 170 mg/kg, and the limits of quantification were in the range of 0. 002 -0. 455 mg/kg. Animal food samples collected from markets such as meat, liver and kidney were analyzed, and the residues of dichlorovos and disulfoton-sulfoxide were found in the some samples. The established method is sensitive and selective enough to detect organophosphorus pesticide residues in animal foods.

Receptor binding assay for paralytic shellfish poisoning toxins: optimization and interlaboratory comparison.

PubMed

Ruberu, Shryamalie R; Liu, Yun-Gang; Wong, Carolyn T; Perera, S Kusum; Langlois, Gregg W; Doucette, Gregory J; Powell, Christine L

2003-01-01

A receptor binding assay (RBA) for detection of paralytic shellfish poisoning (PSP) toxins was formatted for use in a high throughput detection system using microplate scintillation counting. The RBA technology was transferred from the National Ocean Service, which uses a Wallac TriLux 1450 MicroBeta microplate scintillation counter, to the California Department of Health Services, which uses a Packard TopCount scintillation counter. Due to differences in the detector arrangement between these 2 counters, markedly different counting efficiencies were exhibited, requiring optimization of the RBA protocol for the TopCount instrument. Precision, accuracy, and sensitivity [limit of detection = 0.2 microg saxitoxin (STX) equiv/100 g shellfish tissue] of the modified protocol were equivalent to those of the original protocol. The RBA robustness and adaptability were demonstrated by an interlaboratory study, in which STX concentrations in shellfish generated by the TopCount were consistent with MicroBeta-derived values. Comparison of STX reference standards obtained from the U.S. Food and Drug Administration and the National Research Council, Canada, showed no observable differences. This study confirms the RBA's value as a rapid, high throughput screen prior to testing by the conventional mouse bioassay (MBA) and its suitability for providing an early warning of increasing PSP toxicity when toxin levels are below the MBA limit of detection.

A validated high-performance liquid chromatography method with diode array detection for simultaneous determination of nine flavonoids in Senecio cannabifolius Less.

PubMed

Niu, Tian-Zeng; Zhang, Yu-Wei; Bao, Yong-Li; Wu, Yin; Yu, Chun-Lei; Sun, Lu-Guo; Yi, Jing-Wen; Huang, Yan-Xin; Li, Yu-Xin

2013-03-25

A reversed phase high performance liquid chromatography method coupled with a diode array detector (HPLC-DAD) was developed for the first time for the simultaneous determination of 9 flavonoids in Senecio cannabifolius, a traditional Chinese medicinal herb. Agilent Zorbax SB-C18 column was used at room temperature and the mobile phase was a mixture of acetonitrile and 0.5% formic acid (v/v) in water in the gradient elution mode at a flow-rate of 1.0mlmin(-1), detected at 360nm. Validation of this method was performed to verify the linearity, precision, limits of detection and quantification, intra- and inter-day variabilities, reproducibility and recovery. The calibration curves showed good linearities (R(2)>0.9995) within the test ranges. The relative standard deviation (RSD) of the method was less than 3.0% for intra- and inter-day assays. The samples were stable for at least 96h, and the average recoveries were between 90.6% and 102.5%. High sensitivity was demonstrated with detection limits of 0.028-0.085μg/ml for flavonoids. The newly established HPLC method represents a powerful technique for the quality assurance of S. cannabifolius. Copyright © 2012 Elsevier B.V. All rights reserved.

A dynamical approach in exploring the unknown mass in the Solar system using pulsar timing arrays

NASA Astrophysics Data System (ADS)

Guo, Y. J.; Lee, K. J.; Caballero, R. N.

2018-04-01

The error in the Solar system ephemeris will lead to dipolar correlations in the residuals of pulsar timing array for widely separated pulsars. In this paper, we utilize such correlated signals, and construct a Bayesian data-analysis framework to detect the unknown mass in the Solar system and to measure the orbital parameters. The algorithm is designed to calculate the waveform of the induced pulsar-timing residuals due to the unmodelled objects following the Keplerian orbits in the Solar system. The algorithm incorporates a Bayesian-analysis suit used to simultaneously analyse the pulsar-timing data of multiple pulsars to search for coherent waveforms, evaluate the detection significance of unknown objects, and to measure their parameters. When the object is not detectable, our algorithm can be used to place upper limits on the mass. The algorithm is verified using simulated data sets, and cross-checked with analytical calculations. We also investigate the capability of future pulsar-timing-array experiments in detecting the unknown objects. We expect that the future pulsar-timing data can limit the unknown massive objects in the Solar system to be lighter than 10-11-10-12 M⊙, or measure the mass of Jovian system to a fractional precision of 10-8-10-9.

Capillary electrophoresis method with UV-detection for analysis of free amino acids concentrations in food.

PubMed

Omar, Mei Musa Ali; Elbashir, Abdalla Ahmed; Schmitz, Oliver J

2017-01-01

Simple and inexpensive capillary electrophoresis with UV-detection method (CE-UV) was optimized and validated for determination of six amino acids namely (alanine, asparagine, glutamine, proline, serine and valine) for Sudanese food. Amino acids in the samples were derivatized with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) prior to CE-UV analysis. Labeling reaction conditions (100mM borate buffer at pH 8.5, labeling reaction time 60min, temperature 70°C and NBD-Cl concentration 40mM) were systematically investigated. The optimal conditions for the separation were 100mM borate buffer at pH 9.7 and detected at 475nm. The method was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), precision (repeatability) (RSD%) and accuracy (recovery). Good linearity was achieved for all amino acids (r(2)>0.9981) in the concentration range of 2.5-40mg/L. The LODs in the range of 0.32-0.56mg/L were obtained. Recoveries of amino acids ranging from 85% to 108%, (n=3) were obtained. The validated method was successfully applied for the determination of amino acids for Sudanese food samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

An optimized method for neurotransmitters and their metabolites analysis in mouse hypothalamus by high performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry.

PubMed

Yang, Zong-Lin; Li, Hui; Wang, Bing; Liu, Shu-Ying

2016-02-15

Neurotransmitters (NTs) and their metabolites are known to play an essential role in maintaining various physiological functions in nervous system. However, there are many difficulties in the detection of NTs together with their metabolites in biological samples. A new method for NTs and their metabolites detection by high performance liquid chromatography coupled with Q Exactive hybrid quadruple-orbitrap high-resolution accurate mass spectrometry (HPLC-HRMS) was established in this paper. This method was a great development of the applying of Q Exactive MS in the quantitative analysis. This method enabled a rapid quantification of ten compounds within 18min. Good linearity was obtained with a correlation coefficient above 0.99. The concentration range of the limit of detection (LOD) and the limit of quantitation (LOQ) level were 0.0008-0.05nmol/mL and 0.002-25.0nmol/mL respectively. Precisions (relative standard deviation, RSD) of this method were at 0.36-12.70%. Recovery ranges were between 81.83% and 118.04%. Concentrations of these compounds in mouse hypothalamus were detected by Q Exactive LC-MS technology with this method. Copyright © 2016 Elsevier B.V. All rights reserved.

Implementation of a channelized Hotelling observer model to assess image quality of x-ray angiography systems.

PubMed

Favazza, Christopher P; Fetterly, Kenneth A; Hangiandreou, Nicholas J; Leng, Shuai; Schueler, Beth A

2015-01-01

Evaluation of flat-panel angiography equipment through conventional image quality metrics is limited by the scope of standard spatial-domain image quality metric(s), such as contrast-to-noise ratio and spatial resolution, or by restricted access to appropriate data to calculate Fourier domain measurements, such as modulation transfer function, noise power spectrum, and detective quantum efficiency. Observer models have been shown capable of overcoming these limitations and are able to comprehensively evaluate medical-imaging systems. We present a spatial domain-based channelized Hotelling observer model to calculate the detectability index (DI) of our different sized disks and compare the performance of different imaging conditions and angiography systems. When appropriate, changes in DIs were compared to expectations based on the classical Rose model of signal detection to assess linearity of the model with quantum signal-to-noise ratio (SNR) theory. For these experiments, the estimated uncertainty of the DIs was less than 3%, allowing for precise comparison of imaging systems or conditions. For most experimental variables, DI changes were linear with expectations based on quantum SNR theory. DIs calculated for the smallest objects demonstrated nonlinearity with quantum SNR theory due to system blur. Two angiography systems with different detector element sizes were shown to perform similarly across the majority of the detection tasks.

Development of an Ion-Pairing Reagent and HPLC-UV Method for the Detection and Quantification of Six Water-Soluble Vitamins in Animal Feed.

PubMed

Kim, Ho Jin

2016-01-01

A novel and simple method for detecting six water-soluble vitamins in animal feed using high performance liquid chromatography equipped with a photodiode array detector (HPLC/PDA) and ion-pairing reagent was developed. The chromatographic peaks of the six water-soluble vitamins were successfully identified by comparing their retention times and UV spectra with reference standards. The mobile phase was composed of buffers A (5 mM PICB-6 in 0.1% CH3COOH) and B (5 mM PICB-6 in 65% methanol). All peaks were detected using a wavelength of 270 nm. Method validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 25 to 197 μg/kg, and the limits of quantification (LOQs) ranged from 84 to 658 μg/kg. Average recoveries of the six water-soluble vitamins ranged from 82.3% to 98.9%. Method replication resulted in intraday and interday peak area variation of <5.6%. The developed method was specific and reliable and is therefore suitable for the routine analysis of water-soluble vitamins in animal feed.

Precision medicine for cancer with next-generation functional diagnostics.

PubMed

Friedman, Adam A; Letai, Anthony; Fisher, David E; Flaherty, Keith T

2015-12-01

Precision medicine is about matching the right drugs to the right patients. Although this approach is technology agnostic, in cancer there is a tendency to make precision medicine synonymous with genomics. However, genome-based cancer therapeutic matching is limited by incomplete biological understanding of the relationship between phenotype and cancer genotype. This limitation can be addressed by functional testing of live patient tumour cells exposed to potential therapies. Recently, several 'next-generation' functional diagnostic technologies have been reported, including novel methods for tumour manipulation, molecularly precise assays of tumour responses and device-based in situ approaches; these address the limitations of the older generation of chemosensitivity tests. The promise of these new technologies suggests a future diagnostic strategy that integrates functional testing with next-generation sequencing and immunoprofiling to precisely match combination therapies to individual cancer patients.

Liquid chromatographic determination of florfenicol in the plasma of multiple species of fish

USGS Publications Warehouse

Vue, C.; Schmidt, L.J.; Stehly, G.R.; Gingerich, W.H.

2002-01-01

A simple method was developed for determining florfenicol concentration in a small volume (250 mul) of plasma from five phylogenetically diverse species of freshwater fish. Florfenicol was isolated from the plasma matrix through C-18 solid-phase extraction and quantified by reversed-phase high-performance liquid chromatography with UV detection. The accuracy (84-104%), precision (%RSDless than or equal to8), and sensitivity (quantitation limit <30 ng/ml) of the method indicate its usefulness for conducting pharmacokinetic studies on a variety of freshwater fish. Published by Elsevier Science B.V.

A Facile Stable-Isotope Dilution Method for Determination of Sphingosine Phosphate Lyase Activity

PubMed Central

Suh, Jung H.; Eltanawy, Abeer; Rangan, Apoorva; Saba, Julie D.

2015-01-01

A new technique for quantifying sphingosine phosphate lyase activity in biological samples is described. In this procedure, 2-hydrazinoquinoline is used to convert (2E)-hexadecenal into the corresponding hydrazone derivative to improve ionization efficiency and selectivity of detection. Combined utilization of liquid chromatographic separation and multiple reaction monitoring-mass spectrometry allows for simultaneous quantification of the substrate S1P and product (2E)-hexadecenal. Incorporation of (2E)-d5-hexadecenal as an internal standard improves detection accuracy and precision. A simple one-step derivatization procedure eliminates the need for further extractions. Limits of quantification for (2E)-hexadecenal and sphingosine-1-phosphate are 100 and 50 fmol, respectively. The assay displays a wide dynamic detection range useful for detection of low basal sphingosine phosphate lyase activity in wild type cells, SPL-overexpressing cell lines, and wild type mouse tissues. Compared to current methods, the capacity for simultaneous detection of sphingosine-1-phosphate and (2E)-hexadecenal greatly improves the accuracy of results and shows excellent sensitivity and specificity for sphingosine phosphate lyase activity detection. PMID:26408264

The precision of wet atmospheric deposition data from national atmospheric deposition program/national trends network sites determined with collocated samplers

USGS Publications Warehouse

Nilles, M.A.; Gordon, J.D.; Schroder, L.J.

1994-01-01

A collocated, wet-deposition sampler program has been operated since October 1988 by the U.S. Geological Survey to estimate the overall sampling precision of wet atmospheric deposition data collected at selected sites in the National Atmospheric Deposition Program and National Trends Network (NADP/NTN). A duplicate set of wet-deposition sampling instruments was installed adjacent to existing sampling instruments at four different NADP/NTN sites for each year of the study. Wet-deposition samples from collocated sites were collected and analysed using standard NADP/NTN procedures. Laboratory analyses included determinations of pH, specific conductance, and concentrations of major cations and anions. The estimates of precision included all variability in the data-collection system, from the point of sample collection through storage in the NADP/NTN database. Sampling precision was determined from the absolute value of differences in the analytical results for the paired samples in terms of median relative and absolute difference. The median relative difference for Mg2+, Na+, K+ and NH4+ concentration and deposition was quite variable between sites and exceeded 10% at most sites. Relative error for analytes whose concentrations typically approached laboratory method detection limits were greater than for analytes that did not typically approach detection limits. The median relative difference for SO42- and NO3- concentration, specific conductance, and sample volume at all sites was less than 7%. Precision for H+ concentration and deposition ranged from less than 10% at sites with typically high levels of H+ concentration to greater than 30% at sites with low H+ concentration. Median difference for analyte concentration and deposition was typically 1.5-2-times greater for samples collected during the winter than during other seasons at two northern sites. Likewise, the median relative difference in sample volume for winter samples was more than double the annual median relative difference at the two northern sites. Bias accounted for less than 25% of the collocated variability in analyte concentration and deposition from weekly collocated precipitation samples at most sites.A collocated, wet-deposition sampler program has been operated since OCtober 1988 by the U.S Geological Survey to estimate the overall sampling precision of wet atmospheric deposition data collected at selected sites in the National Atmospheric Deposition Program and National Trends Network (NADP/NTN). A duplicate set of wet-deposition sampling instruments was installed adjacent to existing sampling instruments four different NADP/NTN sites for each year of the study. Wet-deposition samples from collocated sites were collected and analysed using standard NADP/NTN procedures. Laboratory analyses included determinations of pH, specific conductance, and concentrations of major cations and anions. The estimates of precision included all variability in the data-collection system, from the point of sample collection through storage in the NADP/NTN database.

Determination of plutonium in spent nuclear fuel using high resolution X-ray

DOE PAGES

McIntosh, Kathryn G.; Reilly, Sean D.; Havrilla, George J.

2015-05-30

Characterization of Pu is an essential aspect of safeguards operations at nuclear fuel reprocessing facilities. A novel analysis technique called hiRX (high resolution X-ray) has been developed for the direct measurement of Pu in spent nuclear fuel dissolver solutions. hiRX is based on monochromatic wavelength dispersive X-ray fluorescence (MWDXRF), which provides enhanced sensitivity and specificity compared with conventional XRF techniques. A breadboard setup of the hiRX instrument was calibrated using spiked surrogate spent fuel (SSF) standards prepared as dried residues. Samples of actual spent fuel were utilized to evaluate the performance of the hiRX. The direct detection of just 39more » ng of Pu is demonstrated. Initial quantitative results, with error of 4–27% and precision of 2% relative standard deviation (RSD), were obtained for spent fuel samples. The limit of detection for Pu (100 s) within an excitation spot of 200 μm diameter was 375 pg. This study demonstrates the potential for the hiRX technique to be utilized for the rapid, accurate, and precise determination of Pu. Moreover, the results highlight the analytical capability of hiRX for other applications requiring sensitive and selective nondestructive analyses.« less

Determination of short chain carboxylic acids in vegetable oils and fats using ion exclusion chromatography electrospray ionization mass spectrometry.

PubMed

Viidanoja, Jyrki

2015-02-27

A new method for quantification of short chain C1-C6 carboxylic acids in vegetable oils and fats by employing Liquid Chromatography Mass Spectrometry (LC-MS) has been developed. The method requires minor sample preparation and applies non-conventional Electrospray Ionization (ESI) liquid phase chemistry. Samples are first dissolved in chloroform and then extracted using water that has been spiked with stable isotope labeled internal standards that are used for signal normalization and absolute quantification of selected acids. The analytes are separated using Ion Exclusion Chromatography (IEC) and detected with Electrospray Ionization Mass Spectrometry (ESI-MS) as deprotonated molecules. Prior to ionization the eluent that contains hydrochloric acid is modified post-column to ensure good ionization efficiency of the analytes. The averaged within run precision and between run precision were generally lower than 8%. The accuracy was between 85 and 115% for most of the analytes. The Lower Limit of Quantification (LLOQ) ranged from 0.006 to 7mg/kg. It is shown that this method offers good selectivity in cases where UV detection fails to produce reliable results. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection of the lunar body tide by the Lunar Orbiter Laser Altimeter

PubMed Central

Mazarico, Erwan; Barker, Michael K; Neumann, Gregory A; Zuber, Maria T; Smith, David E

2014-01-01

The Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter spacecraft collected more than 5 billion measurements in the nominal 50 km orbit over ∼10,000 orbits. The data precision, geodetic accuracy, and spatial distribution enable two-dimensional crossovers to be used to infer relative radial position corrections between tracks to better than ∼1 m. We use nearly 500,000 altimetric crossovers to separate remaining high-frequency spacecraft trajectory errors from the periodic radial surface tidal deformation. The unusual sampling of the lunar body tide from polar lunar orbit limits the size of the typical differential signal expected at ground track intersections to ∼10 cm. Nevertheless, we reliably detect the topographic tidal signal and estimate the associated Love number h2 to be 0.0371 ± 0.0033, which is consistent with but lower than recent results from lunar laser ranging. Key Points Altimetric data are used to create radial constraints on the tidal deformationThe body tide amplitude is estimated from the crossover dataThe estimated Love number is consistent with previous estimates but more precise PMID:26074646

Intraoperative imaging-guided cancer surgery: from current fluorescence molecular imaging methods to future multi-modality imaging technology.

PubMed

Chi, Chongwei; Du, Yang; Ye, Jinzuo; Kou, Deqiang; Qiu, Jingdan; Wang, Jiandong; Tian, Jie; Chen, Xiaoyuan

2014-01-01

Cancer is a major threat to human health. Diagnosis and treatment using precision medicine is expected to be an effective method for preventing the initiation and progression of cancer. Although anatomical and functional imaging techniques such as radiography, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) have played an important role for accurate preoperative diagnostics, for the most part these techniques cannot be applied intraoperatively. Optical molecular imaging is a promising technique that provides a high degree of sensitivity and specificity in tumor margin detection. Furthermore, existing clinical applications have proven that optical molecular imaging is a powerful intraoperative tool for guiding surgeons performing precision procedures, thus enabling radical resection and improved survival rates. However, detection depth limitation exists in optical molecular imaging methods and further breakthroughs from optical to multi-modality intraoperative imaging methods are needed to develop more extensive and comprehensive intraoperative applications. Here, we review the current intraoperative optical molecular imaging technologies, focusing on contrast agents and surgical navigation systems, and then discuss the future prospects of multi-modality imaging technology for intraoperative imaging-guided cancer surgery.

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

McIntosh, Kathryn G.; Reilly, Sean D.; Havrilla, George J.

Characterization of Pu is an essential aspect of safeguards operations at nuclear fuel reprocessing facilities. A novel analysis technique called hiRX (high resolution X-ray) has been developed for the direct measurement of Pu in spent nuclear fuel dissolver solutions. hiRX is based on monochromatic wavelength dispersive X-ray fluorescence (MWDXRF), which provides enhanced sensitivity and specificity compared with conventional XRF techniques. A breadboard setup of the hiRX instrument was calibrated using spiked surrogate spent fuel (SSF) standards prepared as dried residues. Samples of actual spent fuel were utilized to evaluate the performance of the hiRX. The direct detection of just 39more » ng of Pu is demonstrated. Initial quantitative results, with error of 4–27% and precision of 2% relative standard deviation (RSD), were obtained for spent fuel samples. The limit of detection for Pu (100 s) within an excitation spot of 200 μm diameter was 375 pg. This study demonstrates the potential for the hiRX technique to be utilized for the rapid, accurate, and precise determination of Pu. Moreover, the results highlight the analytical capability of hiRX for other applications requiring sensitive and selective nondestructive analyses.« less

Intraoperative Imaging-Guided Cancer Surgery: From Current Fluorescence Molecular Imaging Methods to Future Multi-Modality Imaging Technology

PubMed Central

Chi, Chongwei; Du, Yang; Ye, Jinzuo; Kou, Deqiang; Qiu, Jingdan; Wang, Jiandong; Tian, Jie; Chen, Xiaoyuan

2014-01-01

Cancer is a major threat to human health. Diagnosis and treatment using precision medicine is expected to be an effective method for preventing the initiation and progression of cancer. Although anatomical and functional imaging techniques such as radiography, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) have played an important role for accurate preoperative diagnostics, for the most part these techniques cannot be applied intraoperatively. Optical molecular imaging is a promising technique that provides a high degree of sensitivity and specificity in tumor margin detection. Furthermore, existing clinical applications have proven that optical molecular imaging is a powerful intraoperative tool for guiding surgeons performing precision procedures, thus enabling radical resection and improved survival rates. However, detection depth limitation exists in optical molecular imaging methods and further breakthroughs from optical to multi-modality intraoperative imaging methods are needed to develop more extensive and comprehensive intraoperative applications. Here, we review the current intraoperative optical molecular imaging technologies, focusing on contrast agents and surgical navigation systems, and then discuss the future prospects of multi-modality imaging technology for intraoperative imaging-guided cancer surgery. PMID:25250092

RP-HPLC Method Development and Validation for Determination of Eptifibatide Acetate in Bulk Drug Substance and Pharmaceutical Dosage Forms

PubMed Central

Bavand Savadkouhi, Maryam; Vahidi, Hossein; Ayatollahi, Abdul Majid; Hooshfar, Shirin; Kobarfard, Farzad

2017-01-01

A new, rapid, economical and isocratic reverse phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of eptifibatide acetate, a small synthetic antiplatelet peptide, in bulk drug substance and pharmaceutical dosage forms. The developed method was validated as per of ICH guidelines. The chromatographic separation was achieved isocratically on C18 column (150 x 4.60 mm i.d., 5 µM particle size) at ambient temperature using acetonitrile (ACN), water and trifluoroacetic acid (TFA) as mobile phase at flow rate of 1 mL/min and UV detection at 275 nm. Eptifibatide acetate exhibited linearity over the concentration range of 0.15-2 mg/mL (r2=0.997) with limit of detection of 0.15 mg/mL The accuracy of the method was 96.4-103.8%. The intra-day and inter-day precision were between 0.052% and 0.598%, respectively. The present successfully validated method with excellent selectivity, linearity, sensitivity, precision and accuracy was applicable for the assay of eptifibatide acetate in bulk drug substance and pharmaceutical dosage forms. PMID:28979304

Development and validation of RP HPLC method to determine nandrolone phenylpropionate in different pharmaceutical formulations.

PubMed

Mukherjee, Jayanti; Das, Ayan; Chakrabarty, Uday Sankar; Sahoo, Bijay Kumar; Dey, Goutam; Choudhury, Hira; Pal, Tapan Kumar

2011-01-01

This study describes development and subsequent validation of a reversed phase high performance liquid chromatographic (RP-HPLC) method for the estimation of nandrolone phenylpropionate, an anabolic steroid, in bulk drug, in conventional parenteral dosage formulation and in prepared nanoparticle dosage form. The chromatographic system consisted of a Luna Phenomenex, CN (250 mm x 4.6 mm, 5 microm) column, an isocratic mobile phase comprising 10 mM phosphate buffer and acetonitrile (50:50, v/v) and UV detection at 240 nm. Nandrolone phenylpropionate was eluted about 6.3 min with no interfering peaks of excipients used for the preparation of dosage forms. The method was linear over the range from 0.050 to 25 microg/mL in raw drug (r2 = 0.9994). The intra-day and inter-day precision values were in the range of 0.219-0.609% and 0.441-0.875%, respectively. Limits of detection and quantitation were 0.010 microg/mL and 0.050 microg/mL, respectively. The results were validated according to International Conference on Harmonization (ICH) guidelines in parenteral and prepared nanoparticle formulation. The validated HPLC method is simple, sensitive, precise, accurate and reproducible.

Sensitive determination of tilmicosin, erythromycin ethylsuccinate and clindamycin by CE with electrochemiluminescence detection using azithromycin as internal standard and its applications.

PubMed

Liu, Yan-Ming; Shi, Yan-Mei; Liu, Zhuan-Li; Peng, Long-Fei

2010-05-01

A sensitive approach for the simultaneous determination of tilmicosin, erythromycin ethylsuccinate and clindamycin was developed by CE coupled with electrochemiluminescence detection with ionic liquid. The parameters for CE, electrochemiluminescence detection and the effect of ionic liquid were investigated systematically. The three analytes were well separated and detected within 8 min. The limits of detection (S/N=3) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.4x10(-9), 2.3x10(-8) and 1.3x10(-8) mol/L, respectively. The precisions (RSD%) of the peak area and the migration time are from 0.8 to 1.5% and from 0.2 to 0.5% within a day and from 1.8 to 2.7% and from 0.6 to 0.8% in 3 days, respectively. The limits of quantitation (S/N=10) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.2x10(-8), 2.9x10(-7) and 9.1x10(-8) mol/L in human urines and 5.5x10(-8), 3.2x10(-7) and 2.1x10(-7) mol/L in milk samples, respectively. The recoveries of three analytes at different concentration levels in urine, milk and drugs are between 90.0 and 104.7%. The proposed method was successfully applied to the determination of three analytes in human urine, milk and drugs.

Detection of trace nitric oxide concentrations using 1-D laser-induced fluorescence imaging

NASA Astrophysics Data System (ADS)

Yoo, J.; Lee, T.; Jeffries, J. B.; Hanson, R. K.

2008-06-01

Spectrally resolved laser-induced fluorescence (LIF) with one-dimensional spatial imaging was investigated as a technique for detection of trace concentrations of nitric oxide (NO) in high-pressure flames. Experiments were performed in the burnt gases of premixed methane/argon/oxygen flames with seeded NO (15 to 50 ppm), pressures of 10 to 60 bar, and an equivalence ratio of 0.9. LIF signals were dispersed with a spectrometer and recorded on a 2-D intensified CCD array yielding both spectral resolution and 1-D spatial resolution. This method allows isolation of NO-LIF from interference signals due to alternative species (mainly hot O2 and CO2) while providing spatial resolution along the line of the excitation laser. A fast data analysis strategy was developed to enable pulse-by-pulse NO concentration measurements from these images. Statistical analyses as a function of laser energy of these single-shot data were used to determine the detection limits for NO concentration as well as the measurement precision. Extrapolating these results to pulse energies of ˜ 16 mJ/pulse yielded a predicted detection limit of ˜ 10 ppm for pressures up to 60 bar. Quantitative 1-D LIF measurements were performed in CH4/air flames to validate capability for detection of nascent NO in flames at 10-60 bar.

Test of CCD Precision Limits for Differential Photometry

NASA Technical Reports Server (NTRS)

Borucki, W. J.; Dunham, E. W.; Wei, M. Z.; Robinson, L. B.; Ford, C. H.; Granados, A. F.

1995-01-01

Results of tests to demonstrate the very high differential-photometric stability of CCD light sensors are presented. The measurements reported here demonstrate that in a controlled laboratory environment, a front-illuminated CCD can provide differential-photometric measurements with reproducible precision approaching one part in 105. Practical limitations to the precision of differential-photometric measurements with CCDs and implications for spaceborne applications are discussed.