These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Exclusion Chromatography  

NSDL National Science Digital Library

This site contains a brief description of the separation mechanism in size exclusion chromatography. The picture helps visualize the separation, but the site features a simplified and idealized presentation useful for students new to the concept.

Kimball, John W.

2011-05-03

2

Instrumentation: Ion Chromatography.  

ERIC Educational Resources Information Center

Discusses the importance of ion chromatography in separating and measuring anions. The principles of ion exchange are presented, along with some applications of ion chromatography in industry. Ion chromatography systems are described, as well as ion pair and ion exclusion chromatography, column packings, detectors, and programming. (TW)

Fritz, James S.

1987-01-01

3

Determination of alcohols in pharmaceuticals by ion-exclusion chromatography.  

PubMed

Alcohols present in pharmaceutical intravenous solutions (e.g. propylene glycol and ethanol) are separated from each other and common matrix components by an ion-exclusion column with a dilute sulfuric acid mobile phase. Using refractive index detection, the assay is characterized by an absolute detection limit of 1 ng and a linear dynamic range for both area and height which spans three orders of magnitude. Chromatographic ruggedness is sufficiently high so that strict system suitability criteria can be met even after 600 injections have been made. Long-term detector stability is enhanced through the use of a flowing reference cell. PMID:3597584

Iwinski, G; Jenke, D R

1987-04-17

4

Ion chromatography  

Microsoft Academic Search

Ion chromatography makes it possible to separate and measure low concentrations of up to 8 or 10 different anions in a single chromatographic run that takes only a few minutes. The method also works well for cations. Alkali metal ions, ammonium, magnesium, calcium, strontium, and a growing list of other metal cations and amine cations can also be rapidly separated

James S. Fritz

1987-01-01

5

Ion Chromatography.  

ERIC Educational Resources Information Center

Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)

Mulik, James D.; Sawicki, Eugene

1979-01-01

6

Two separation modes combined in one column: sequential ion-exchange separation and size-exclusion chromatography of green fluorescent protein  

Microsoft Academic Search

Purification of green fluorescent protein from a crude solution has been investigated using a combined system of ion-exchange chromatography and size-exclusion chromatography packed into one column of a continuous annular chromatograph. Performing the chromatography with two different sorbents packed into a single column reduces transfer losses and the hold steps between the two separation steps can be eliminated. Appropriate running

Andrea Uretschlaeger; Alois Jungbauer

2002-01-01

7

A process for separating acid-sugar mixtures using ion exclusion chromatography  

SciTech Connect

Work using a low-temperature concentrated sulfuric acid hydrolysis process to convert the cellulosic fraction of corn stover to monomeric sugars demonstrated the high conversion efficiencies possible with that process. The TVA work also confirmed the need for a cost-effective acid-sugar separation process. A preparative-scale ion-exclusion chromatography (IEC) system was designed, constructed, and tested with a variety of synthetic solutions and actual hydrolyzates. Although significant dispersion was observed initially, design changes were effective in minimizing this phenomenon. Data collected during the operation of the preparative-scale system were used in the design and construction of an IEC miniplant capable of processing larger volumes of synthetic solutions or hydrolyzates and in the design of an extraction-assisted IEC system. The data were also used to assess the viability of a continuous feed IEC system. This paper includes a discussion of the IEC process, provides overall material balances for various IEC process scenarios, and presents a discussion on process economics.

Hester, R.D.; Hartfield, S.W. [University of Southern Mississippi, Hattiesburg, MS (United States); Farina, G.E. [Tennessee Valley Authority, Muscle Shoals, AL (United States)

1994-10-01

8

Continuous ion-exclusion chromatography system for acid/sugar separation  

SciTech Connect

A simulated moving bed ion exclusion chromatography system was constructed for the continuous separation of the components in an aqueous feed solution of sucrose and sulfuric acid. A system of 18 columns was arrayed about a central manifold system. Each column was packed with approximately 820 mL of porous cationic exchange resin. The system was designed for the flexibility to use fluid recycle loops and unrestricted placement of all inlet and outlet streams. Monitoring and control functions were performed using a Camile 2000 process controller integrated with a custom-built control computer. The aqueous feed solution, usually containing 10 wt.% sucrose and 10 wt.% sulfuric acid, was generally introduced into the system at a rate of roughly 2 L/hr. Approximately 4 L/hr of water was used to elute materials through the separation system. After optimization, the separation system allowed greater than 95% recovery of the feed sucrose in an exit stream containing 8.8 wt.% sucrose and 98% recovery of the feed acid in a second exit stream containing 5 wt.% acid.

Springfield, R.M.; Hester, R.D. [Univ. of Southern Mississippi, Hattiesburg, MS (United States)] [Univ. of Southern Mississippi, Hattiesburg, MS (United States)

1999-04-01

9

[Analysis of aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography].  

PubMed

The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid, perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection. The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column (TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column (TSKgel Super IC-A/C). Good separation was performed on the TSKgel SCX in shorter retention times. For the TSKgel Super IC-A/C, peak shape of the acids was sharp and symmetrical in spite of longer retention times. In addition, the mutual separation of the acids was good except for iso- and n-butyric acids. The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C connected in series), lower concentrations of PFBA and sulfuric acid as eluents, non-suppressed conductivity detection and UV detection at 210 nm. This analysis was applied to anaerobic digestion process waters. The chromatograms with conductivity detection were relatively simpler compared with those of UV detection. The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices. PMID:22799193

Ito, Kazuaki; Sakamoto, Jun; Nagaoka, Kazuya; Takayama, Yohichi; Kanahori, Takashi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

2012-04-01

10

Separation of acid and sugar by ion exclusion chromatography. An application in the conversion of cellulose to ethanol  

SciTech Connect

The production of fuel grade alcohol by fermentation from sugars obtained by the acid hydrolysis of cellulose has been hindered by costly methods of cleansing the acid in the sugar stream. An economical and environmentally acceptable acid-sugar separation process based on ion exclusion chromatography has been developed and analyzed. This process recovers the acid for reuse in hydrolysis without producing landfill waste allowing a concentrated acid hydrolysis process to be commercially feasible.

Hartfield, S.; Hester, R. [Univ. of Southern Mississippi, Hattiesburg, MS (United States)

1993-12-31

11

Qualitative analysis of some carboxylic acids by ion-exclusion chromatography with atmospheric pressure chemical ionization mass spectrometric detection.  

PubMed

A simple, selective and sensitive method for the determination of carboxylic acids has been developed. A mixture of formic, acetic, propionic, valeric, isovaleric, isobutyric, and isocaproic acids has been separated on a polymethacrylate-based weak acidic cation-exchange resin (TSK gel OA pak-A) based on an ion-exclusion chromatographic mechanism with detection using UV-photodiode array, conductivity and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). A mobile phase consisting of 0.85 mM benzoic acid in 10% aqueous methanol (pH 3.89) was used to separate the above carboxylic acids in about 40 min. For LC-MS, the APCI interface was used in the negative ionization mode. Linear plots of peak area versus concentration were obtained over the range 1-30 mM (r2=0.9982) and 1-30 mM (r2=0.9958) for conductimetric and MS detection, respectively. The detection limits of the target carboxylic acids calculated at S/N=3 ranged from 0.078 to 2.3 microM for conductimetric and photometric detection and from 0.66 to 3.82 microM for ion-exclusion chromatography-APCI-MS. The reproducibility of retention times was 0.12-0.16% relative standard deviation for ion-exclusion chromatography and 1.21-2.5% for ion-exclusion chromatography-APCI-MS. The method was applied to the determination of carboxylic acids in red wine, white wine, apple vinegar, and Japanese rice wine. PMID:12108651

Helale, Murad I H; Tanaka, Kazuhiko; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Haddad, Paul R

2002-05-17

12

Biosynthesis of Cd-bound phytochelatins by Phaeodactylum tricornutum and their speciation by size-exclusion chromatography and ion-pair chromatography coupled to ICP-MS.  

PubMed

Cd-bound phytochelatins (Cd-PCs) have been synthesised by incubation of Phaeodactylum tricornutum cell cultures with Cd and purified by size-exclusion chromatography-UV-Vis. These complexes, which were identified in previous work, have now been used as model substances to develop and optimise ion-pair chromatography (IPC) coupled to inductively coupled plasma-mass spectrometry (ICP-MS) for analysis of Cd-PCs. Subsequent analysis of samples taken from Silene vulgaris plants cultivated under heavy metal stress conditions revealed Cd signals but no Cd-PC signals. By use of isotopically enriched (116)Cd-PCs the sample preparation steps were verified to determine the stability of the analytes. We observed species transformation between Cd-PCs and other unidentified Cd complexes. Consequently, the kinetic and thermodynamic lability of Cd-PCs are decisive factors in their detection. PMID:16205894

Loreti, Valeria; Toncelli, Daniel; Morelli, Elisabetta; Scarano, Gioacchino; Bettmer, Jörg

2005-10-01

13

[Determination of organic acids in rice wine by ion-exclusion chromatography].  

PubMed

An ion-exclusion chromatographic method for the simultaneous determination of organic acids in rice wine was developed. An IC-Pak Ion Exclusion column (300 mm x 7.8 mm, 7 microm) was used at 50 degrees C. The mobile phases were H2SO4 (phase A) and acetonitrile (phase B) (98:2, v/v) at a flow rate of 0.5 mL/min. The gradient elution program was as follows: 0-40 min, 0.01 mol/L H2SO4 to 0.02 mol/L H2SO4; 40-50 min, 0.01 mol/L H2SO4. The injection volume was 10 microL. The detection wavelength was set at 210 nm. The results showed that oxalic acid, maleic acid, citric acid, tartaric acid, malic acid, ascorbic acid, succinic acid, lactic, fumaric acid, acetic acid, propionic acid, isobutyric acid and butyric acid were completely separated and determined in 30 min. The linear correlation coefficients were above 0.999 7 in the range of 0.001- 1.000 g/L. Under the optimized conditions, the recoveries of organic acids in rice wine were in the range of 93.4% - 103.8% with the relative standard deviations (RSDs, n = 5) of 0.1% - 1.5%. This method is feasible, convenient, fast, accurate and applicable for the quantitative analysis of the organic acids in rice wine. PMID:24984473

Lin, Xiaojie; Wei, Wei; He, Zhigang; Lin, Xiaozi

2014-03-01

14

Comparison of Various Preparation Methods for Determination of Organic Acids in Fruit Vinegars with a Simple Ion-Exclusion Liquid Chromatography  

Microsoft Academic Search

An ion-exclusion liquid chromatography with mobile phase 0.005 mol L?1 H2SO4 and step flow rate gradient (0.2 mL min?1 in the first 40 min and 0.5 mL min?1 from 41 to 60 min) was used to determine 20 organic acids simultaneously at 17 °C within 51 min. The peak resolutions (Rs)\\u000a were 0.45?3.02 and separation factors (?) were all higher than 1. Impurities in fruit vinegar executed with direct injection

Jau-Tien Lin; Shih-Chuan Liu; You-Cheng Shen; Deng-Jye Yang

15

Ion Chromatography: An Account of Its Conception and Early Development  

ERIC Educational Resources Information Center

The conception of ion chromatography and its development into a technique ready for commercialization is described. The pioneering development pointed the way to make ion exclusion an important member of the repertoire of IC methods.

Small, Hamish

2004-01-01

16

Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.  

PubMed

The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent. PMID:12830883

Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

2003-05-16

17

Precise determination of dissolved silica in seawater by ion-exclusion chromatography isotope dilution inductively coupled plasma mass spectrometry.  

PubMed

Ion exclusion chromatograph (IEC) isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS) (IEC-ID-ICP-MS) was developed for measurement of dissolved silica in seawater, which was applied to production of certified reference materials (CRMs) of three concentration levels of nutrients (high, medium and low levels). IEC-ICP-MS has been employed to separate dissolved silica from seawater matrix. In the present study, in order to solve substantial problems due to spectral interference in ICP-MS and to improve the accuracy of IEC-ICP-MS beyond standard addition or conventional calibration methods, ID method was coupled with ICP-sector field mass spectrometry (operated under medium resolution,i.e., m/?m=4000). In addition, effects of various operating parameters in ICP-MS on a silicon background level were also investigated to obtain lower background equivalent concentration (BEC). As a result, 3 ng g(-1) of the BEC and 0.5 % of relative standard uncertainties were achieved in the analyses of dissolved silica in seawater samples at concentration levels from 4.0 mg kg (-1) to 0.8 mg kg(-1) as silicon. The developed method was successfully validated by analyses of an artificial seawater containing a known amount of silicate and the seawater certified reference material MOOS-2 produced by the National Research Council Canada. PMID:25086888

Nonose, Naoko; Cheong, Chikako; Ishizawa, Yukari; Miura, Tsutomu; Hioki, Akiharu

2014-08-20

18

A novel ion-exclusion chromatography-mass spectrometry method to measure concentrations and cycling rates of carbohydrates and amino sugars in freshwaters.  

PubMed

The concentrations of free neutral carbohydrates and amino sugars were determined in freshwater samples of distinct matrix complexity, including meso-, eu- and dystrophic lakes and ponds, using high-performance ion-exclusion chromatography (HPIEC) coupled to mass spectrometry (MS). In contrast to other methods, our approach allowed the quantification of free neutral carbohydrates and amino sugars at low nM concentrations without derivatization, de-salting or pre-concentration. New sample preparation procedures were applied prior to injection employing syringe and hollow fiber filtration. Analytes were separated on a strong cation exchange resin under 100% aqueous conditions using 0.1% formic acid as a mobile phase. To minimize background noise in MS, analytes were detected in a multiple reaction monitoring scan mode with double ion filtering. Detection limits of carbohydrates and amino sugars ranged between 0.2 and 2nM at a signal-to-noise ratio >5. Error ranged between 1 and 12% at 0.5-500nM levels. Using a stable isotope dilution approach, both the utilization and recycling of glucose in Lake Zurich was observed. In contrast, N-acetyl-glucosamine was equally rapidly consumed but there was no visible de novo production. The simple and rapid sample preparation makes our protocol suitable for routine analyses of organic compounds in freshwater samples. Application of stable isotope tracers along with accurate measures of carbohydrate and amino sugar concentrations enables novel insights into the compound in situ dynamics. PMID:25242224

Hor?ák, Karel; Pernthaler, Jakob

2014-10-24

19

Characterization of Nanocrystalline CdSe by Size Exclusion Chromatography  

E-print Network

in solution. This paper demonstrates the application of high-performance size exclusion chromatography (HPSECCharacterization of Nanocrystalline CdSe by Size Exclusion Chromatography Karl M. Krueger, Ali M 6100 Main Street, Houston, Texas 77005 High-performance size exclusion chromatography (HPSEC

20

Soil & Water Lab, Ion Chromatography Procedure Page 1 Ion Chromatography Procedure  

E-print Network

Soil & Water Lab, Ion Chromatography Procedure Page 1 Ion Chromatography Procedure Last updated: 5.29.13 A. Introduction Ion chromatography (IC) is used to separate out various ions based on their charge if a new machine part is needed. D. Stock Solution Preparation #12;Soil & Water Lab, Ion Chromatography

Walter, M.Todd

21

Ion Exchange and Liquid Column Chromatography.  

ERIC Educational Resources Information Center

Emphasizes recent advances in principles and methodology in ion exchange and chromatography. Two tables list representative examples for inorganic ions and organic compounds. Cites 544 references. (CS)

Walton, Harold F.

1980-01-01

22

Principles and applications of steric exclusion chromatography.  

PubMed

We introduce a chromatography method for purification of large proteins and viruses that works by capturing them at a non-reactive hydrophilic surface by their mutual steric exclusion of polyethylene glycol (PEG). No direct chemical interaction between the surface and the target species is required. We refer to the technique as steric exclusion chromatography. Hydroxyl-substituted polymethacrylate monoliths provide a hydrophilic surface and support convective mass transport that is unaffected by the viscosity of the PEG. Elution is achieved by reducing PEG concentration. Selectivity correlates with molecular size, with larger species retained more strongly than smaller species. Retention increases with PEG size and concentration. Salts weaken retention in proportion to their concentration and Hofmeister ranking. Retention is enhanced near the isoelectric point of the target species. Virus binding capacity was measured at 9.9×10(12) plaque forming units per mL of monolith. 99.8% of host cell proteins and 93% of DNA were eliminated. Mass recovery exceeded 90%. IgM capacity was greater than 60 mg/mL. 95% of host cell proteins were eliminated from IgM produced in protein-free media, and mass recovery was up to 90%. Bioactivity was fully conserved by both viruses and antibodies. Process time ranged from less than 30 min to 2 h depending on the product concentration in the feed stream. PMID:23182281

Lee, Jeremy; Gan, Hui Theng; Latiff, Sarah Maria Abdul; Chuah, Cindy; Lee, Wan Yee; Yang, Yuan-Sheng; Loo, Bernard; Ng, Say Kong; Gagnon, Pete

2012-12-28

23

Size exclusion chromatography does not require pores  

PubMed Central

Separation of macromolecules on the basis of their molecular weight by size exclusion chromatography has long been considered to be caused by the geometry-dependent partition of macromolecules between a continuous phase and the porous interior of a gel or cross-linked bead. The volume of a pore accessible to a solute is limited by its relative dimensions, so larger molecules will have access to a smaller volume and will remain in a bead for a shorter time than smaller solutes. Our recent alternate picture proposes that the partition coefficient can be calculated from a thermodynamic model for the free energy of mixing of the solute with the gel phase. Size-dependent exclusion caused by the unfavorable entropy of mixing associated with the partition is predicted; the magnitude of the effect is modified by enthalpic interactions between the solute and the gel phase. This concept is extended here to describe the partition of macromolecules into a layer of terminally attached polymer chains grafted onto a solid bead. Both simple mean field and self-consistent field theory calculations predict size-dependent entropic exclusion. Experimental results obtained with neutral polymer chains grafted onto solid polystyrene latex beads confirm the predictions. PMID:10852951

Brooks, Donald E.; Haynes, Charles A.; Hritcu, Doina; Steels, Bradley M.; Muller, Werner

2000-01-01

24

Size exclusion chromatography does not require pores  

NASA Astrophysics Data System (ADS)

Separation of macromolecules on the basis of their molecular weight by size exclusion chromatography has long been considered to be caused by the geometry-dependent partition of macromolecules between a continuous phase and the porous interior of a gel or cross-linked bead. The volume of a pore accessible to a solute is limited by its relative dimensions, so larger molecules will have access to a smaller volume and will remain in a bead for a shorter time than smaller solutes. Our recent alternate picture proposes that the partition coefficient can be calculated from a thermodynamic model for the free energy of mixing of the solute with the gel phase. Size-dependent exclusion caused by the unfavorable entropy of mixing associated with the partition is predicted; the magnitude of the effect is modified by enthalpic interactions between the solute and the gel phase. This concept is extended here to describe the partition of macromolecules into a layer of terminally attached polymer chains grafted onto a solid bead. Both simple mean field and self-consistent field theory calculations predict size-dependent entropic exclusion. Experimental results obtained with neutral polymer chains grafted onto solid polystyrene latex beads confirm the predictions.

Brooks, Donald E.; Haynes, Charles A.; Hritcu, Doina; Steels, Bradley M.; Müller, Werner

2000-06-01

25

Using Ion Exchange Chromatography to Separate and Quantify Complex Ions  

ERIC Educational Resources Information Center

Ion exchange chromatography is an important technique in the separation of charged species, particularly in biological, inorganic, and environmental samples. In this experiment, students are supplied with a mixture of two substitution-inert complex ions. They separate the complexes by ion exchange chromatography using a "flash"…

Johnson, Brian J.

2014-01-01

26

Chromatography  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into chromatography including the basics, the three types (affinity, ion exchange, size exclusion), and the parts and functions associated with chromatography.

2011-11-29

27

Nonaqueous ion-exchange chromatography and electrophoresis  

Microsoft Academic Search

Compiling ion-exchange chromatographic data, which has been allowed by recent developments in chromatographic techniques, indicates that solvation plays important roles in determining selectivity. Ion-exchange chromatography in nonaqueous solvents is not a novel idea, but is expected to give insights into roles of solvation in separation mechanisms, because changing solvents is the simplest way to study solvation effects. Thus, nonaqueous media

Tetsuo Okada

1998-01-01

28

Permeation of Small Molecules in Aqueous Size-Exclusion Chromatography Vis-a` -Vis Models  

E-print Network

Permeation of Small Molecules in Aqueous Size-Exclusion Chromatography Vis-a` -Vis Models for size- exclusion chromatography, is defined as the fraction of the column pore volume into which in size-exclusion chromatography (SEC) is the absence of a fundamental relationship between the retention

Dubin, Paul D.

29

The History of Ion Chromatography: The Engineering Perspective  

ERIC Educational Resources Information Center

The development of ion chromatography from an engineering perspective is presented. As ion chromatography became more widely accepted, researchers developed dozens of standard applications that enabled the creation of many low-end instruments.

Evans, Barton

2004-01-01

30

Application of artificial intelligence to ion chromatography  

NASA Astrophysics Data System (ADS)

INDUCT an induction method, Principal Components Regression (PCR) and Linear Discriminant Analysis (LDA) were applied to the classification of ion chromatographic detectors. Information about the sample and other IC method conditions (19 attributes in total); a training set of 12693 cases and a randomly chosen test set of 1410 cases wore used. INDUCT classification method correctly predicted the detector in 95.5% of the training set and 94% of the test set. PCR correctly predicted the detector in 27% of the training set and 28% of the test set. By creating a variable (taking a value between 0 (absent) and 1 (present)) for each value of each attribute, the PCR prediction for both sets increased to 60%. LDA was more successful, predicting 69% of the detectors of each set, using a prior probability of the frequency of a given detector in the database, but this included zero hits for detectors that were poorly represented in the database. Induction methods performed the best among all the other methods with a success rate of 94%. Then we describe the development and maintenance of an expert system to advise on the configuration of systems for ion exclusion chromatography (IEC). The aim of the system is to define appropriate conditions for the separation of desired groups of acids or bases. The system is implemented in a rule-based system, MCRDR (Multiple Classification Ripple Down Rules), which offers multiple conclusions from rules based on the attributes of the system. Because of the nature of the ``Ripple Down Rules'' approach, in which new knowledge is always added as an amendment to an existing conclusion (and therefore cannot interfere with other conclusions), the expert or user can maintain and alter the system easily according to their own needs without the help of a software engineer. For a set of 83 cases, although the expert system only agreed with the published conditions in 53% of cases, when the predictions were assessed by a recognised IC expert, 88% were pronounced ``workable''. The software user interface is friendly where the user can easily select case from pop up lists.

Ramadan, Ziad

1999-10-01

31

Optimization Strategies in Ion Chromatography  

Microsoft Academic Search

The ion chromatographer is often concerned with the separation of complex mixtures with a variable behavior of their components, which makes good resolution and reasonable analysis time sometimes extremely difficult. Several optimization strategies have been proposed to solve this problem. The most reliable and less time consuming strategies apply resolution criteria based on theoretical or empirical retention models to describe

Tomislav Bolan?a

2007-01-01

32

Measurements of Protein-Protein Interactions by Size Exclusion Chromatography  

E-print Network

A method is presented for determining second virial coefficients B_2 of protein solutions from retention time measurements in size exclusion chromatography (SEC). We determine B_2 by analyzing the concentration dependance of the chromatographic partition coefficient. We show the ability of this method to track the evolution of B_2 from positive to negative values in lysozyme and bovine serum albumin solutions. Our SEC results agree quantitatively with data obtained by light scattering.

J. Bloustine; V. Berejnov; S. Fraden

2003-06-12

33

Fast, reproducible size-exclusion chromatography of biological macromolecules  

Microsoft Academic Search

The size-dependent separation of biological macromolecules can be effectively carried out using size-exclusion chromatography (SEC) on silica-based HPLC columns. For this technique to be successful, appropriate methods should be chosen. This paper presents practical guidelines for the development of reproducible SEC methods based upon optimized sample volume, flow-rate, column length and use of mobile phase conditions that reduce non-ideal SEC

R. D. Ricker; L. A. Sandoval

1996-01-01

34

ION-EXCLUSION CHROMATOGRAPHIC DETERMINATION OF CARBOXYLIC ACIDS USED TO SUPPORT THE MICROBIALLY MEDIATED REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE  

EPA Science Inventory

An analytical method was developed for the determination of lactic acid, formic acid, acetic acid, propionic acid, and butyric acid in environmental microcosm samples using ion-exclusion chromatography. The chromatographic behavior of various eluents was studied to determine the ...

35

Static and dynamic polystyrene dimensions in relation to the blob model and size-exclusion chromatography  

E-print Network

-exclusion chromatography Z. Gallot, G. Pouyet and A. Schmitt Centre de Recherches sur les Macromolécules, 6, rue, chromatographie d'exclusion stérique) pour une série de polystyrènes linéaires en solution dans un bon solvant-over spatial). En chromatographie d'exclusion stérique, nous montrons qu'il est possible d'établir plusieurs

Paris-Sud XI, Université de

36

Polydispersity in size-exclusion chromatography: A stochastic approach.  

PubMed

We investigate the impact of polydispersity of the sample molecules on the separation process and on the efficiency of size-exclusion chromatography. Polydispersity was integrated into the molecular (stochastic) model of chromatography; the characteristic function, the band profile and the most important moments of the elution profiles were calculated for several kind of pore structures. We investigated the parameters affected by polydispersity on the separation for a number of pore shapes. Our results demonstrate that even a small distribution in the molecular size (i.e. polydispersity) can contribute substantially to the total width of the chromatographic peak. The pure effect of polydispersity can only be investigated via mathematical modeling, because its contribution to an experimental chromatogram cannot be separated from other band-broadening effects. PMID:25262029

Sepsey, Annamária; Bacskay, Ivett; Felinger, Attila

2014-10-24

37

Size-exclusion chromatography system for macromolecular interaction analysis  

DOEpatents

A low pressure, microcomputer controlled system employing high performance liquid chromatography (HPLC) allows for precise analysis of the interaction of two reversibly associating macromolecules such as proteins. Since a macromolecular complex migrates faster than its components during size-exclusion chromatography, the difference between the elution profile of a mixture of two macromolecules and the summation of the elution profiles of the two components provides a quantifiable indication of the degree of molecular interaction. This delta profile is used to qualitatively reveal the presence or absence of significant interaction or to rank the relative degree of interaction in comparing samples and, in combination with a computer simulation, is further used to quantify the magnitude of the interaction in an arrangement wherein a microcomputer is coupled to analytical instrumentation in a novel manner.

Stevens, Fred J. (Downers Grove, IL)

1988-01-01

38

Determination of water-soluble low-molecular-weight organic acids in soils by ion chromatography  

Microsoft Academic Search

Low-molecular-weight organic acids (LOAs) widely occur in soils and affect the soil properties and processes. We developed a simplified and relatively rapid method to identify and quantify the water-soluble LOAs in soils by using ion chromatography with an exclusive column for organic acids, an ion exchange column for anions, and an electric conductivity detector. These combinations enabled to separate more

Masayuki Tani; Kayoko Shinjo Shida; Kiyoshi Tsutsuki; Renzo Kondo

2001-01-01

39

Gradient ion chromatography of inositol phosphates.  

PubMed

Inositol phosphates including phytic acid were separated in 30 min by gradient ion chromatography with postcolumn derivatization. All four pentakisphosphates were resolved, while four tetrakisphosphate peaks were detected. The limits of detection for all polyphosphates, including tris- and bisphosphates, were between 1 and 2 nmol. The method was used to compare nonenzymatic dephosphorylation of inositol hexakisphosphate at pH 4.0 versus pH 10.8. The only pentakisphosphate detected in calf brains was identified as myo-inositol 1,3,4,5,6-pentakisphosphate. The major pentakisphosphate in raw soybean seeds was myo-inositol 1,2,4,5,6-pentakisphosphate of unknown enantiomeric composition, while lesser amounts of myo-inositol 1,2,3,4,5-pentakisphosphate of unknown enantiomeric composition, myo-inositol 1,2,3,4,6-pentakisphosphate, and myo-inositol 1,3,4,5,6-pentakisphosphate were also present. PMID:3245565

Phillippy, B Q; Bland, J M

1988-11-15

40

Preliminary report on fractionation of fucans by ion-exchange displacement centrifugal partition chromatography.  

PubMed

A new method combining ion-exchange displacement chromatography with centrifugal partition chromatography (CPC) was used for the fractionation of partially depolymerized fucans (polysulphated polysaccharides). The ion-exchanger was Amberlite LA2, a high-molecular-mass liquid secondary amine miscible with most common organic solvents and immiscible with aqueous solutions. Ion-exchange displacement centrifugal partition chromatography was performed with LA2 in methyl isobutyl ketone (MiBK) as the stationary phase, water as the mobile phase, Cl- as the carrier and OH- as the displacer. A complex mixture of partially depolymerized fucans was resolved into adjacent families characterized by their peak molecular mass and polydispersity. The Dubois test (sugar) and the azur A test (SO3-) confirmed the displacement mode of the process, and size-exclusion chromatographic controls confirmed its efficiency. PMID:9544806

Chevolot, L; Colliec-Jouault, S; Foucault, A; Ratiskol, J; Sinquin, C

1998-02-27

41

Ion Exchange Chromatography and Spectrophotometry: An Introductory Undergraduate Laboratory Experiment.  

ERIC Educational Resources Information Center

Describes an experiment in which students use ion exchange chromatography to separate a mixture of chloro complexes of transition metal ions and then use spectrophotometry to define qualitatively the efficiency of the ion exchange columns. Background information, materials needed, and procedures used are included. (JN)

Foster, N.; And Others

1985-01-01

42

Methods to reduce fronting and increase yield in batch size exclusion chromatography  

Microsoft Academic Search

Peak fronting occurs in size exclusion chromatography, SEC, resulting in 10% loss in insulin yield. The goal of this project is to understand the mechanism of insulin peak fronting and develop a strategy to reduce fronting and increase insulin yield in SEC. ^ Chromatography experiments ruled out pressure surge, viscous fingering, and adsorption as the cause for fronting. Theoretical analysis

Chi-Ming Yu

2005-01-01

43

Determining the molar mass of a plasma substitute succinylated gelatin by size exclusion chromatography–multi-angle laser light scattering, sedimentation equilibrium and conventional size exclusion chromatography  

Microsoft Academic Search

The clinical effectiveness of succinylated gelatin as a plasma substitute depends strongly on its molar mass, determined conventionally by size exclusion chromatography (SEC). This study evaluates different SEC calibration standards in comparison with two independent “absolute” methods for determining the weight average molar mass (Mw) of a succinylated gelatin sample. SEC calibrated using succinylated gelatin fractions correlated well with size

Manjit Kaur; Kornelia Jumel; Kim R. Hardie; Andrea Hardman; John Meadows; Colin D. Melia

2002-01-01

44

Solute affinity in ion-exchange displacement chromatography  

Microsoft Academic Search

In this paper a new graphical method, derived from the Steric Mass Action model of non-linear ion-exchange chromatography, is presented for the determination of solute affinity in ion exchange displacement systems. The affinity of solutes in these systems is described by a dynamic affinity parameter which is a function of the linear steric mass action parameters of the solutes and

Clayton A. Brooks; Steven M. Cramer

1996-01-01

45

The determination of some anions using ion chromatography and ion chromatography-graphite furnace atomic absorption spectrometry  

E-print Network

chromatography. The samples were prepared for analysis by an oxygen bomb combustion technique. NBS coal standard 1632 contained 71+14 ppm F, while 1632a contained 98+10 ppm F. These values are in agreement with values reported in the literature, as determined... with a fluoride ion selective electrode. The fluorine concentration in the Texas lignite core sample ranged from 50 to 95 ppm F. Ion chromatography alone was shown not to be useful in the deter- mination of selenite and selenate in natural water...

Hillman, Daniel C

2012-06-07

46

Mineral Separation in a CELSS by Ion-exchange Chromatography  

NASA Technical Reports Server (NTRS)

Operational parameters pertinent to ion exchange chromatography separation were identified. The experiments were performed with 9 mm diameter ion exchange columns and conventional column accessories. The cation separation beds were packed with AG 50W-X2 strong acid cation exchange resin in H(+) form and 200-400 dry mesh particle size. The stripper beds used in some experiments were packed with AG 1-XB strong base cation exchange resin in OH(-) form and 200-400 dry mesh particle size.

Ballou, E. V.; Spitze, L. A.; Wong, F. W.; Wydeven, T.; Johnson, C. C.

1982-01-01

47

Ion-exchange chromatography by dicarboxyl cellulose gel  

Microsoft Academic Search

A new column packing material for ion-exchange chromatography was prepared from cellulose gel by periodate oxidation followed by chlorite oxidation to form spatially paired carboxyl groups (dicarboxyl cellulose, DCC). The carboxyl group was quantitatively introduced to spherical cellulose gel by controlling the extent of oxidation. The DCC gels were examined for their ion-exchange activity for various amines at pH of

Ung-Jin Kim; Shigenori Kuga

2001-01-01

48

Separation and determination of polythionates by ion-pair chromatography  

SciTech Connect

Reversed-phase ion-pair chromatography with conductivity detection provides a rapid and efficient technique for the quantitative separation of polythionates, sulfate, thiosulfate, and dithionate. Tetraalkylammonium salts were used as ion-pair reagents. Separations were accomplished in less than 15 min., with detection limits in the low parts-per-million range, except for S/sub 5/O/sub 6//sup 2 -/. Retention was dependent on the nature of both the cation and the anion of the ion-air reagent. 18 references, 2 tables.

Rabin, S.B.; Stanbury, D.M.

1985-05-01

49

Recycling Size Exclusion Chromatography for the Analysis and Separation of Nanocrystalline Gold  

E-print Network

Recycling Size Exclusion Chromatography for the Analysis and Separation of Nanocrystalline Gold Ali here the application of this method to gold nanocrystals stabilized by thiols. Alternate recycling tool. For example, after recycling processes an initially broad and chromatographic feature from a gold

Richards-Kortum, Rebecca

50

Mathematical modeling and scale-up of size-exclusion chromatography  

Microsoft Academic Search

Size exclusion chromatography (SEC) is a widely used tool in bioseparations. Because its separation mechanism is based on the permeability of macromolecules rather than any type of binding, the feed volume to bed volume ratio is usually quite small. Thus, large columns are typically used in preparative- and large scale separations. In this work, a general rate model considering various

Zhiguo Li; Yesong Gu; Tingyue Gu

1998-01-01

51

Preparative Subfractionation of Petroleum Resins and Asphaltenes. II. Characterization of Size Exclusion Chromatography Isolated Fractions  

Microsoft Academic Search

In the first study of this series, resins and asphaltenes from stable and unstable crude oils have been separated by size exclusion chromatography in three molecular mass ranges (MM: high, medium, and low). In the present study, the isolated fractions were further characterized in order to correlate several of their structural properties with crude oil tendency to solid deposition. Elemental

Lante Carbognani; Joussef Espidel

2003-01-01

52

Application of Ion Chromatography to the Investigation of Real-World Samples Rebecca J. Whelan,*1  

E-print Network

Application of Ion Chromatography to the Investigation of Real-World Samples Rebecca J. Whelan,*1 Experiment #4: Ion Chromatography Handout prepared by David Rakestraw, Rebecca Whelan, Theresa Hannon, and Cheol Keun Chung I. Summary of Laboratory In this laboratory we will use ion chromatography to analyze

Zare, Richard N.

53

Multidimensional separations of complex peptide mixtures: a combined high-performance liquid chromatography/ion mobility/  

E-print Network

chromatography/ion mobility/ time-of-flight mass spectrometry approach Stephen J. Valentine1, *, Manoj Kulchania chromatography (HPLC) has been combined with high-resolution ion mobility separations and time-of-flight mass-dimensional liquid chromatography-ion mobility separations (LC-IMS) and three-dimensional LC-IMS-MS separations

Clemmer, David E.

54

Evaluation of New Microparticulate Packings for Aqueous Steric Exclusion Chromatography  

Microsoft Academic Search

Two types of high performance aqueous size exclusion columns have recently been developed, one a rigid spherical silica-based packing containing a new hydrophilic bonded phase (MicroPak TSK Gel Type SW) and the other an organic-based, semi-rigid gel (MicroPak TSK Gel Type PW). Characteristics of MicroPak TSK SW and PW columns were compared to other commercially available aqueous SEC columns packed

Thomas V. Alfredson; C. Timothy Wehr; Lori Tallman; Fred Klink

1982-01-01

55

Determination of chloride in geological samples by ion chromatography  

USGS Publications Warehouse

Samples of silicate rocks are prepared by sodium carbonate fusion and then treated by ion chromatography. The method was tested for geological standards with chloride concentration between 0.003 and 3%. Observed chloride concentrations comparedd favorably with literature values. The relative standard deviation and detection limit for the method were 8% and 7 ppm, respectively. Up to 30 determination per 24-hour period were possible. ?? 1983.

Wilson, S. A.; Gent, C. A.

1983-01-01

56

Investigation of the photocatalytic degradation of brown water natural organic matter by size exclusion chromatography  

Microsoft Academic Search

Herein we report on the photocatalytic degradation of natural organic matter from a bog lake (Lake Hohloh, Black Forest, Germany) as followed by size exclusion chromatography with dissolved organic carbon (DOC) and ultraviolet (?=254nm) detection (SEC-DOC and SEC-UV). When irradiating this humic-rich water in the presence of 0.5gL?1 titanium dioxide (P25), we found a preferential degradation of the higher molecular

Luis A. Tercero Espinoza; Eike ter Haseborg; Matthias Weber; Fritz H. Frimmel

2009-01-01

57

Pore structural characterization of monolithic silica columns by inverse size-exclusion chromatography  

Microsoft Academic Search

In this work, a parallel pore model (PPM) and a pore network model (PNM) are developed to provide a state-of-art method for the calculation of several characteristic pore structural parameters from inverse size-exclusion chromatography (ISEC) experiments. The proposed PPM and PNM could be applicable to both monoliths and columns packed with porous particles. The PPM and PNM proposed in this

Brian A. Grimes; Romas Skudas; Klaus K. Unger; Dieter Lubda

2007-01-01

58

Preparation and characterization of spherical polymer packings from polybutadiene for size-exclusion chromatography  

Microsoft Academic Search

Porous polymer spherical particles for column packings in nonaqueous size-exclusion chromatography (SEC) were prepared from 1,2-syndiotactic polybutadiene by suspension and evaporation method. The polymer microbeads obtained were crosslinked by radical reaction between 2-vinyl groups in polybutadiene with ultraviolet radiation, to render them insoluble. These microbeads have wider chromatographic separation width than polystyrene column packings. In addition, the polybutadiene microbeads did

S. Nagaoka; T. Satoh; K. Sakamoto; H. Ihara

2005-01-01

59

Size-exclusion liquid chromatography and capillary electrophoresis of pollen allergens  

Microsoft Academic Search

Allergens from the pollen of Phleum pratense, Dactylis glomerata. Arrhenatherum elatius, Secale cereale, Lolium perrene and Festuca sp. were analysed by size-exclusion chromatography (SEC) and capillary electrophoresis (CE). SEC was used for the determination of the molecular masses of main allergens. A CE method, using either 150 mmol\\/1 phosphoric acid (pH 1.8) or a micellar system consisting of 50 mmol\\/l

V?ra Pacáková; Jitka Pechancová; Karel Štulík

1996-01-01

60

Ion chromatography in the manufacture of multilayer circuit boards  

SciTech Connect

Ion chromatography (IC) has proven useful in analyzing chemical solutions used in the manufacture of multilayer circuit boards. The manufacturing process is described briefly and previously published IC methods are reviewed. Then, methods are described for determining chlorate and chlorite in a brown oxide solution; salicylic acid in an epoxy cure agent; formate, sulfate, and tartrate in an electroless copper bath; anionic detergents in a tin-lead brightener and in a cleaning solution; and aqueous photoresist and nonionic brightener in a tin-lead bath. Anion exchange, reverse phase HPLC on a poly(styrene/divinylbenzene), PS/DVB, column and two-dimensional liquid chromatography also are described. Chemically suppressed conductivity and photometric detection are used. 13 refs., 10 figs., 1 tab.

Smith, R.E.

1990-09-01

61

Chromatography  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students "learn about the phases of molecular separation, and then experiment with paper and ion chromatography." The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In addition, visitors will find an overview of the activity, assessments, and concepts and their correlation to AAAS and NSES standards.

2008-08-14

62

Determination of selected anions in water by ion chromatography  

USGS Publications Warehouse

Ion chromatography is a rapid, sensitive, precise, and accurate method for the determination of major anions in rainwater 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 mg/L for fluoride to 0.20 mg/L for chloride and sulfate. Relative standard deviations were less than 9% 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 mg/L in rainfall samples. Precision for fluoride ranged from 12 to 22%, 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%. 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%. 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. (USGS).

Fishman, Marvin J.; Pyen, Grace

1979-01-01

63

Liquid Chromatography in 1982.  

ERIC Educational Resources Information Center

Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

Freeman, David H.

1982-01-01

64

Early milestones in the development of ion-exchange chromatography: a personal account  

Microsoft Academic Search

Ion chromatography as we know it today was built on a foundation of knowledge accumulated over a period of many years. Here, we review some of the outstanding earlier achievements in ion-exchange chromatography. Beginning about 1947, Spedding and Powell at Iowa State published a series of papers describing practical methods for preparative separation of the rare earths by displacement ion-exchange

James S Fritz

2004-01-01

65

What can in situ ion chromatography offer for Mars exploration?  

PubMed

The successes of the Mars exploration program have led to our unprecedented knowledge of the geological, mineralogical, and elemental composition of the martian surface. To date, however, only one mission, the Phoenix lander, has specifically set out to determine the soluble chemistry of the martian surface. The surprising results, including the detection of perchlorate, demonstrated both the importance of performing soluble ion measurements and the need for improved instrumentation to unambiguously identify all the species present. Ion chromatography (IC) is the state-of-the-art technique for soluble ion analysis on Earth and would therefore be the ideal instrument to send to Mars. A flight IC system must necessarily be small, lightweight, low-power, and have low eluent consumption. We demonstrate here a breadboard system that addresses these issues by using capillary IC at low flow rates with an optimized eluent generator and suppressor. A mix of 12 ions known or plausible for the martian soil, including 4 (oxy)chlorine species, has been separated at flow rates ranging from 1 to 10 ?L/min, requiring as little as 200 psi at 1.0 ?L/min. This allowed the use of pneumatic displacement pumping from a pressurized aluminum eluent reservoir and the elimination of the high-pressure pump entirely (the single heaviest and most energy-intensive component). All ions could be separated and detected effectively from 0.5 to 100 ?M, even when millimolar concentrations of perchlorate were present in the same mixtures. PMID:24963874

Shelor, C Phillip; Dasgupta, Purnendu K; Aubrey, Andrew; Davila, Alfonso F; Lee, Michael C; McKay, Christopher P; Liu, Yan; Noell, Aaron C

2014-07-01

66

Ion Chromatography as a Reference Method for Determination of Inorganic Ions in Water and Wastewater  

Microsoft Academic Search

Water analysis is an important part of the chemical analysis of environmental samples. The development of new methods of water analysis and improvement of existing ones is a major task for analytical chemists. Analysis of common inorganic anions and cations in water is mandatory. Ion chromatography has almost replaced most of the wet chemical methods used in water analysis. The

Rajmund Michalski

2006-01-01

67

Evaluation of steric exclusion chromatography on cryogel column for the separation of serum proteins.  

PubMed

Steric exclusion chromatography (SXC) is a new mode of protein chromatography, in which large proteins are retained on hydrophilic stationary phase surface due to the steric exclusion of polyethylene glycol (PEG) in the mobile phase, and thereafter the retained proteins can be eluted by reducing PEG concentration. In this work, SXC was evaluated on a polyacrylamide cryogel monolith. Microscopic observation of ?-globulin precipitates on the gel surface in SXC was reported for the first time. Due to the compact packing of protein precipitates on the stationary phase surface, the dynamic retention capacity of the cryogel monolith for ?-globulin reached 20 mg/mL bed volume, much higher than those of cryogel beds in adsorption-based chromatography. The effect of molecular weight and concentration of PEG, solution pH and salt concentration on protein retention capacity was in agreement with the earlier work on SXC. Because the cryogel monoliths with interconnected macropores (10-100 ?m) allow much easy flow-through of viscous PEG buffer, the SXC can be operated at low back pressure. Hence, the cryogel monoliths are more suitable for SXC than other monoliths of narrow pores reported previously. In the separation of bovine serum proteins, albumin was recovered in the breakthrough fraction with high purity, and globulin was over eight times concentrated in the elution pool. This work has, thus, demonstrated the rapid serum protein separation and concentration by SXC on the cryogel monolith columns. PMID:24552971

Wang, Chuan; Bai, Shu; Tao, Shi-Peng; Sun, Yan

2014-03-14

68

Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography  

SciTech Connect

Here we demonstrate that separation of proteolytic peptides, having the same net charge and one basic residue, is affected by their specific orientation toward the stationary phase in ion-exchange chromatography. In electrostatic repulsion-hydrophilic interaction chromatography (ERLIC) with an anion-exchange material, the C-terminus of the peptides is, on average, oriented toward the stationary phase. In cation exchange, the average peptide orientation is the opposite. Data with synthetic peptides, serving as orientation probes, indicate that in tryptic/Lys-C peptides the C-terminal carboxyl group appears to be in a zwitterionic bond with the side chain of the C-terminal Lys/Arg residue. In effect, the side chain is then less basic than the N-terminus, accounting for the specific orientation of tryptic and Lys-C peptides. Analyses of larger sets of peptides, generated from lysates by either Lys-N, Lys-C, or trypsin, reveal that specific peptide orientation affects the ability of harged side chains, such as phosphate residues, to influence retention. Phosphorylated residues that are remote in the sequence from the binding site affect retention less than those that are closer. When a peptide contains multiple charged sites, then orientation is observed to be less rigid and retention tends to be governed by the peptide’s net charge rather than its sequence. These general observations could be of value in confirming a peptide’s identification and, in particular, phosphosite assignments in proteomics analyses. More generally, orientation accounts for the ability of chromatography to separate peptides of the same compositionbut different sequence.

Alpert, Andrew J.; Petritis, Konstantinos; Kangas, Lars J.; Smith, Richard D.; Mechtler, Karl; Mitulovic, Goran; Mohammed, Shabaz; Heck, Albert J.

2010-06-15

69

Simultaneous spectrophotometric determination of phosphate and silicate ions in river water by using ion-exclusion chromatographic separation and post-column derivatization.  

PubMed

The simultaneous spectrophotometric determination of phosphate and silicate ions in river water was examined by using ion-exclusion chromatography and post-column derivatization. Phosphate and silicate ions were separated by the ion-exclusion column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the H(+)-form (TSKgel Super IC-A/C) by using ultra pure water as an eluent. After the post-column derivatization with molybdate and ascorbic acid, so-called molybdenum-blue, both ions were determined simultaneously by spectrophotometry. The effects of sulfuric acid, sodium molybdate and ascorbic acid concentrations and reaction coil length, which have relation to form the reduced complexes of molybdate and ions, on the detector response for phosphate and silicate ions were investigated. Under the optimized conditions (color-forming reactant, 50 mM sulfuric acid-10 mM sodium molybdate; reducing agent, 50 mM ascorbic acid; reaction coil length, 6 m), the calibration curves of phosphate and silicate ions were linear in the range of 50-2000 microg L(-1) as P and 250-10,000 microg L(-1) as Si. This method was successfully applied to water quality monitoring of Kurose-river watershed and it suggested that the effluent from a biological sewage treatment plant was significant source of phosphate ion in Kurose-river water. PMID:18539182

Nakatani, Nobutake; Kozaki, Daisuke; Masuda, Wakako; Nakagoshi, Nobukazu; Hasebe, Kiyoshi; Mori, Masanobu; Tanaka, Kazuhiko

2008-06-30

70

Ultra-high performance size-exclusion chromatography of synthetic polymers: demonstration of capability.  

PubMed

Ultra-high performance size-exclusion chromatography (UHP SEC) is a newly developed disruptive technology that allows the high-resolution separation of synthetic polymers in as little as 2 min. The capability of UHP SEC for the characterization of synthetic polymers in organic solvents has been demonstrated. Using the Waters ACQUITY UPLC® H-Class system and ethylene-bridged hybrid size-exclusion chromatography (SEC) columns packed with 1.7 to 2.5-?m particles with pore sizes ranging from 45 to 900 Å, size-based separations of polystyrene and poly(methyl methacrylate) standards in tetrahydrofuran and poly(ethylene oxide) standards in 20 mM ammonium acetate in methanol are achieved within 2-4 min. The speed of analysis is about ten times faster than conventional SEC separations, and greater resolution is achieved. Average molecular weights of selected commercial polymers have been determined using ultra-high performance and conventional SEC. Average M data of analyzed samples are in good agreement using the two approaches. An inherent limitation of SEC in UHP mode is the characterization of very high M polymers (above ca. 2 million Da) due to the deformation and/or mechanical shearing of large molecules at high flow rates. PMID:23821608

Janco, Miroslav; Alexander, James N; Bouvier, Edouard S P; Morrison, Damian

2013-09-01

71

Multicolour Fluorescence-Detection Size-Exclusion Chromatography for Structural Genomics of Membrane Multiprotein Complexes  

PubMed Central

Many interesting and important membrane proteins are hetero-oligomeric. However, besides naturally abundant examples, the structures of relatively few such complexes are known. Partly, this is due to difficulties in expression, stoichiometric assembly, and in the evaluation of their stability prior to crystallization trials. Here we describe a new approach, which allows rapid assessment of protein complex quality, assembly and stoichiometry, simplifying the search for conditions conducive to long-term stability and crystallization. Multicolour fluorescence size-exclusion chromatography (MC-FSEC) is used to enable tracking of individual subunits through expression, solubilization and purification steps. We show how the method has been applied to the heterodimeric transporter associated with antigen processing (TAP) and demonstrate how it may be extended in order to analyse membrane multisubunit assemblies. PMID:23825631

Parcej, David; Guntrum, Renate; Schmidt, Sabine; Hinz, Andreas; Tampé, Robert

2013-01-01

72

Size-exclusion liquid chromatography and capillary electrophoresis of pollen allergens.  

PubMed

Allergens from the pollen of Phleum pratense, Dactylis glomerata. Arrhenatherum elatius, Secale cereale, Lolium perrene and Festuca sp. were analysed by size-exclusion chromatography (SEC) and capillary electrophoresis (CE). SEC was used for the determination of the molecular masses of main allergens. A CE method, using either 150 mmol/l phosphoric acid (pH 1.8) or a micellar system consisting of 50 mmol/l sodium dodecyl sulphate-20 mmol/l borate (pH 9.35), was developed as a rapid and efficient alternative to SEC, especially for process control of allergenic preparations. The results obtained by the two methods confirmed similarities in the structures of the studied pollen allergens. PMID:8798911

Pacáková, V; Pechancová, J; Stulík, K

1996-05-31

73

Size-exclusion chromatography using self-organized nanopores in anodic porous alumina  

NASA Astrophysics Data System (ADS)

We have achieved the size separation of DNA molecules on a biochip using an anodic porous alumina as a separation matrix in electrophoresis. The bottom of the microfluid channel on the chip was made of a porous alumina membrane that has uniform nanoscale pores on its surface. Since smaller molecules are much more frequently trapped by nanopores than larger ones, larger molecules elute earlier than smaller molecules. This type of separation is the same process as that resulting from size-exclusion chromatography. When two kinds of DNA samples (3.2 and 0.3 kilobases) were applied to the biochip, they were clearly separated into two bands, with the larger molecules (3.2 kilobases) eluting earlier. Since nanopore formation does not require any nanolithography, the fabrication is easy and inexpensive. The matrix can be integrated with other biomicroelectromechanical systems reactors on a micro total analysis system chip.

Sano, Tohru; Iguchi, Noriyuki; Iida, Kazuhiro; Sakamoto, Toshitsugu; Baba, Masakazu; Kawaura, Hisao

2003-11-01

74

J. Phys. Chem. 1994,98, 7063-7067 7063 Evaluation of Models for Size Exclusion Chromatography of Asymmetric Solutes  

E-print Network

of Asymmetric Solutes M. A. Kuntz,? P.L.Dubin,' J. I. Kaplan,*and M. S.Mebtai Department of Chemistry, Indiana consider two presentations regarding the size exclusion chromatography of highly asymmetric solutes: one on measurements of K- for the rigid rodlike and spherical solutes schizophyllan and ficoll, respectively, and also

Dubin, Paul D.

75

Characterization of atmospheric organic matter using size-exclusion chromatography with inline organic carbon detection  

NASA Astrophysics Data System (ADS)

The atmosphere contains a substantial amount of water-soluble organic material in aerosols, clouds and fogs. Despite years of efforts, little is known on the structure, composition and properties of this organic matter with most studies focusing on individual species while the bulk of the organic matter remains poorly characterized. In this work high-performance size-exclusion chromatography coupled with inline organic carbon detection (SEC-DOC) is used to characterize organic matter in fogs, clouds and aerosols collected in Fresno (CA), Whistler (BC), Davis (CA) and Selinsgrove (PA). The molecular weight distributions showed a fractional overlap of atmospheric samples and terrestrial fulvic acids although for clouds and aerosols the smaller molecular weight (MW) material is dominant. This smaller MW material is clearly resolved. Cloud and fog samples showed a larger fraction of small molecular weight organic species compared to the water-soluble fraction of aerosols, consistent with the partitioning of small molecular weight volatile species into the atmospheric aqueous phase. There are overall little differences between different sites for a same type of sample. These results obtained by one analytical set-up were confirmed with a second size-exclusion chromatography set-up using a different column and detection system. Size distributions for the same sampling location showed little inter-event variability and water-soluble organic carbon (WSOC) samples were slightly shifted toward larger sizes compared to clouds and fogs, consistent with an important contribution of volatile species to the latter ones. Cloud and aerosol samples contributed to a significant fraction (up to 21% of dissolved organic carbon (DOC)) of the macromolecular scale material.

Wang, Youliang; Chiu, Chao-An; Westerhoff, Paul; Valsaraj, Kalliat T.; Herckes, Pierre

2013-04-01

76

Potentiometric sensors with ion-exchange Donnan exclusion membranes.  

PubMed

Potentiometric sensors that exhibit a non-Hofmeister selectivity sequence are normally designed by selective chemical recognition elements in the membrane. In other situations, when used as detectors in separation science, for example, membranes that respond equally to most ions are preferred. With so-called liquid membranes, a low selectivity is difficult to accomplish since these membranes are intrinsically responsive to lipophilic species. Instead, the high solubility of sample lipids in an ionophore-free sensing matrix results in a deterioration of the response. We explore here potentiometric sensors on the basis of ion-exchange membranes commonly used in fuel cell applications and electrodialysis, which have so far not found their way into the field of ion-selective electrodes. These membranes act as Donnan exclusion membranes as the ions are not stripped of their hydration shell as they interact with the membrane. Because of this, lipophilic ions are no longer preferred over hydrophilic ones, making them promising candidates for the detection of abundant ions in the presence of lipophilic ones or as detectors in separation science. Two types of cation-exchanger membranes and one anion-exchange membrane were characterized, and potentiometric measuring ranges were found to be Nernstian over a wide range down to about 10 ?M concentrations. Depending on the specific membrane, lipophilic ions gave equal response to hydrophilic ones or were even somewhat discriminated. The medium and long-term stability and reproducibility of the electrode signals were found to be promising when evaluated in synthetic and whole blood samples. PMID:23731350

Grygolowicz-Pawlak, Ewa; Crespo, Gastón A; Ghahraman Afshar, Majid; Mistlberger, Günter; Bakker, Eric

2013-07-01

77

A fluorescence-detection size-exclusion chromatography-based thermostability assay for membrane protein precrystallization screening.  

PubMed

Optimization of membrane protein stability under different solution conditions is essential for obtaining crystals that diffract to high resolution. Traditional methods that evaluate protein stability require large amounts of material and are, therefore, ill suited for medium- to high-throughput screening of membrane proteins. Here we present a rapid and efficient fluorescence-detection size-exclusion chromatography-based thermostability assay (FSEC-TS). In this method, the target protein is fused to GFP. Heated protein samples, treated with a panel of additives, are then analyzed by FSEC. FSEC-TS allows one to evaluate the thermostability of nanogram-to-microgram amounts of the target protein under a variety of conditions without purification. We applied this method to the Danio rerio P2X4 receptor and Caenorhabditis elegans GluCl to screen ligands, ions, and lipids, including newly designed cholesterol derivatives. In the case of GluCl, the screening results were used to obtain crystals of the receptor in the presence of lipids. PMID:22884106

Hattori, Motoyuki; Hibbs, Ryan E; Gouaux, Eric

2012-08-01

78

Direct determination of free cyanide in drinking water by ion chromatography with pulsed amperometric detection  

Microsoft Academic Search

Cyanide is a regulated contaminant in drinking water in the United States. This paper describes an ion chromatography method with pulsed amperometric detection (PAD) that directly determines free cyanide in drinking water. Samples are treated with sodium hydroxide to stabilize cyanide and with a cation-exchange cartridge to remove transition metals. Cyanide is separated by anion-exchange chromatography and detected by PAD

Terri T. Christison; Jeffrey S. Rohrer

2007-01-01

79

High-performance chromatofocusing and size-exclusion chromatography: separation of human uterine estrogen-binding proteins.  

PubMed

We have employed high-performance chromatofocusing (HPCF) and high-performance size exclusion chromatography (HPSEC) to separate and identify radiolabelled estrogen binding proteins present in human uterine cytosol. Results obtained using these high-performance methods are compared to results of similar analyses by conventional isoelectric focusing procedures and open-column size exclusion chromatography. By HPCF, descending pH gradients (pH 8-4) allow us to discern four to five estrogen binding proteins with elution pH values typically between pH 4.5 and 7.2. However, when using HPCF, significant quantities of estrogen binding proteins are rarely detected between pH 7.2 and 8.0. This observation has been confirmed by open-column chromatofocusing of these proteins on Polybuffer Exchanger 94. In contrast, preparative isoelectric focusing by electrophoresis in polyampholytes reveals substantial quantities of estrogen binding activity eluted between pH 7.5 and 8.0. Several possible explanations for this disparity are discussed. Apparent differences are also observed when the size heterogeneity of estrogen binding proteins is analyzed simultaneously by size exclusion chromatography in open-column (Sephacryl S-300) and high-performance (TSK-3000SW) modes. HPSEC of these estrogen binding proteins on TSK-3000SW columns demonstrates a predominant 80-85 A species, whereas size exclusion chromatography on conventional Sephacryl S-300 columns reveals two to three distinct regions of estrogen binding proteins with Stokes radii of ca. 85, 60 and 30 A (major species). The larger form of receptor, whether a non-specific aggregate or a multisubunit complex, is stable in unfractionated cytosol and becomes more labile only during size exclusion chromatography. PMID:6490762

Hutchens, T W; Gibbons, W E; Besch, P K

1984-08-01

80

Determination of Ethylene Glycol Degradation Products in Chromium Plating and Associated Polishing Solutions by Ion Chromatography.  

National Technical Information Service (NTIS)

Ethylene glycol resulting from cooling system leaks can adversely affect plating properties when added to chromium plating and associated polishing solutions. Ion chromatography can be used to monitor these leaks by quantitatively determining the glycolic...

S. Sopok

1988-01-01

81

Determination of Phosphate in Cola Beverages Using Nonsuppressed Ion Chromatography: An Experiment Introducing Ion Chromatography for Quantitative Analysis  

NASA Astrophysics Data System (ADS)

The determination of inorganic anions was very difficult until the development of ion chromatography (IC). The two techniques for performing the conductivity detection are 'single column' or 'non suppressed' IC and 'suppressed' IC. Non suppressed IC (NSIC) is generally the selected technique because of its simple instrumentation: with the addition of a conductivity detector, any standard HPLC system can perform NSIC. Thus, according to the importance of IC, it is advisable the development of some IC experiments that could be integrated into existing laboratory courses in analytical chemistry. In this paper, the determination of phosphate in cola beverages by NSIC is introduced. Cola beverages are actually relatively rich in phosphoric acid, and may be considered as very suitable laboratory samples for the experiments. In the practical session, each student analyzes at least 3 different colas, and calculates the phosphate concentration and its relative standard deviation from replicate injections of the same cola brand (Repeatability). From the students' reports, the instructor evaluates the reproducibility using the results obtained by different students for the same cola brands. A relative difference among brands was detected in our experiments. The application of one-way-ANOVA to the collected results confirmed that the brands differ significantly.

Bello, M. A.; Gonzalez, A. Gustavo

1996-12-01

82

Chromatography  

NSDL National Science Digital Library

This site provides fundamental background information about chromatography, including plate theory, rate theory, the mechanisms of separations, and qualitative and quantitative aspects of chromatography. The format is a series of PowerPoint-like presentations available in PDF format.

Hardy, James K.

2011-05-16

83

Ion chromatography characterization of polysaccharides in ancient wall paintings.  

PubMed

An analytical procedure for the characterisation of polysaccharides and the identification of plant gums in old polychrome samples is described. The procedure is based on hydrolysis with 2 M trifluoroacetic acid assisted by microwaves (20 min, 120 degrees C, 500 W), clean-up of the hydrolysate by an ion-exchange resin, and analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Using this method the hydrolysis time was reduced to 20 min and the chromatographic separation of seven monosaccharides (fucose, rhamnose, arabinose, galactose, glucose, mannose, xylose) and two uronic acids (galacturonic and glucuronic) was achieved in 40 min. The whole analytical procedure allows sugar determination in plant gums at picomole levels, with an average recovery of 72% with an RSD of 8% as tested on arabic gum. The analytical procedure was tested with several raw gums, watercolour samples and reference painting specimens prepared according to old recipes at the Opificio delle Pietre Dure of Florence (Italian Ministry of Cultural Heritage, Italy). All the data collected expressed in relative sugar percentage contents were submitted to principal components analysis for gum identification: five groups were spatially separated and this enabled the identification of arabic, tragacanth, karaya, cherry+ghatty, and guar+locust bean gum. Wall painting samples from Macedonian tombs (Greece) of the 4th-3rd Centuries B.C., processed by the suggested method, showed the presence of a complex paint media mainly consisting of tragacanth and fruit tree gums. Moreover, starch had probably been added to plaster as highlighted by the presence of a huge amount of glucose. PMID:12236518

Colombin, Maria Perla; Ceccarini, Alessio; Carmignani, Alessia

2002-08-30

84

Sequential phosphoproteomic enrichment through complementary metal-directed immobilized metal ion affinity chromatography.  

PubMed

Methodologies to enrich heterogeneous types of phosphopeptides are critical for comprehensive mapping of the under-explored phosphoproteome. Taking advantage of the distinct binding affinities of Ga(3+) and Fe(3+) for phosphopeptides, we designed a metal-directed immobilized metal ion affinity chromatography for the sequential enrichment of phosphopeptides. In Raji B cells, the sequential Ga(3+)-Fe(3+)-immobilized metal affinity chromatography (IMAC) strategy displayed a 1.5-3.5-fold superior phosphoproteomic coverage compared to single IMAC (Fe(3+), Ti(4+), Ga(3+), and Al(3+)). In addition, up to 92% of the 6283 phosphopeptides were uniquely enriched in either the first Ga(3+)-IMAC (41%) or second Fe(3+)-IMAC (51%). The complementary properties of Ga(3+) and Fe(3+) were further demonstrated through the exclusive enrichment of almost all of 1214 multiply phosphorylated peptides (99.4%) in the Ga(3+)-IMAC, whereas only 10% of 5069 monophosphorylated phosphopeptides were commonly enriched in both fractions. The application of sequential Ga(3+)-Fe(3+)-IMAC to human lung cancer tissue allowed the identification of 2560 unique phosphopeptides with only 8% overlap. In addition to the above-mentioned mono- and multiply phosphorylated peptides, this fractionation ability was also demonstrated on the basic and acidic phosphopeptides: acidophilic phosphorylation sites were predominately enriched in the first Ga(3+)-IMAC (72%), while Pro-directed (85%) and basophilic (79%) phosphorylation sites were enriched in the second Fe(3+)-IMAC. This strategy provided complementary mapping of different kinase substrates in multiple cellular pathways related to cancer invasion and metastasis of lung cancer. Given the fractionation ability and ease of tip preparation of this Ga(3+)-Fe(3+)-IMAC, we propose that this strategy allows more comprehensive characterization of the phosphoproteome both in vitro and in vivo. PMID:24313913

Tsai, Chia-Feng; Hsu, Chuan-Chih; Hung, Jo-Nan; Wang, Yi-Ting; Choong, Wai-Kok; Zeng, Ming-Yao; Lin, Pei-Yi; Hong, Ruo-Wei; Sung, Ting-Yi; Chen, Yu-Ju

2014-01-01

85

Organic acid eluents for single-column ion chromatography  

SciTech Connect

Various organic acids are tested for use as eluents in single-column anion chromatography. Adsorption and dissociation characteristics of the acids are related to eluent strength and selectivity variations. Sensitivities and background conductances of these eluents are also compared to other common eluents used in single-and dual-column anion chromatography. Conclusions are drawn concerning the selection and advantages of acid eluents. 9 references, 3 figures, 7 tables.

Fritz, J.S.; DuVal, D.L.; Barron, R.E.

1984-06-01

86

COMPARISON OF COLLECTION PROCEDURES FOR THE REINJECTION ION CHROMATOGRAPHY OF WATER  

EPA Science Inventory

Four collection protocols for the heart-cutting procedure in ion chromatography were compared statistically to determine the best method for use in the analysis of trace ions in water. In the comparison, the protocols were applied in the analysis of 0.1 to 0.4-ppm AS(V) added to ...

87

ANALYSIS OF NITRITE IN NO2 DIFFUSION TUBES USING ION CHROMATOGRAPHY  

EPA Science Inventory

An analytical method was developed for the analysis of the NO2 collected by a passive diffusion controlled atmospheric sampling device. The method measured the total amount of nitrite ion using ion chromatography. The precision obtained under field conditions, defined as twice th...

88

[Determination of tetrodotoxin in fermentation broth of distiller's yeast by ion chromatography].  

PubMed

A method was developed for the quantitative analysis of tetrodotoxin (TTX) in fermentation broth of distiller's yeast by ion chromatography. After extraction with acetonitrile solution (containing 0.1% phosphoric acid) and purification with an ion-exchange column, the tetrodotoxin was separated by ion chromatography and detected by a ultraviolet-visible (UV-VIS) absorbance detector. The experimental results showed that the tetrodotoxin had a good linearity (r2 = 0.997) in the range of 10 - 100 mg/L and the detection limit (3 of signal-to-noise ratio) was 1.0 mg/L. The average recoveries were between 90% - 103% with a relative standard deviation lower than 4.9%. The analysis of real samples verified the reliability of this method and demonstrated that the ion chromatography can be used for the quantification detection of the tetrodotoxin. The degradation experiment results suggested that distiller's yeast had a remarkable effect on the tetrodotoxin degradation. PMID:21598524

Shu, Jing; Li, Bailin; Ou, Jie

2011-02-01

89

Ion-exchange chromatography separation applied to mineral recycle in closed systems  

NASA Technical Reports Server (NTRS)

As part of the controlled ecological life support system (CELSS) program, a study is being made of mineral separation on ion-exchange columns. The purpose of the mineral separation step is to allow minerals to be recycled from the oxidized waste products of plants, man, and animals for hydroponic food production. In the CELSS application, relatively large quantities of minerals in a broad concentration range must be recovered by the desired system, rather than the trace quantities and very low concentrations treated in analytical applications of ion-exchange chromatography. Experiments have been carried out to assess the parameters pertinent to the scale-up of ion-exchange chromatography and to determine feasibility. Preliminary conclusions are that the column scale-up is in a reasonable size range for the CELSS application. The recycling of a suitable eluent, however, remains a major challenge to the suitability of using ion exchange chromatography in closed systems.

Ballou, E.; Spitze, L. A.; Wong, F. W.; Wydeven, T.; Johnson, C. C.

1981-01-01

90

Multidimensional profiling of plasma lipoproteins by size exclusion chromatography followed by reverse-phase protein arrays  

PubMed Central

The composition of lipoproteins and the association of proteins with various particles are of much interest in the context of cardiovascular disease. Here, we describe a technique for the multidimensional analysis of lipoproteins and their associated apolipoproteins. Plasma is separated by size exclusion chromatography (SEC), and fractions are analyzed by reverse-phase arrays. SEC fractions are spotted on nitrocellulose slides and incubated with different antibodies against individual apolipoproteins or antibodies against various apolipoproteins. In this way, tens of analytes can be measured simultaneously in 100 ?l of plasma from a single SEC separation. This methodology is particularly suited to simultaneous analysis of multiple proteins that may change their distribution to lipoproteins or alter their conformation, depending on factors that influence circulating lipoprotein size or composition. We observed changes in the distribution of exchangeable apolipoproteins following addition of recombinant apolipoproteins or interaction with exogenous compounds. While the cholesteryl ester transfer protein (CETP)-dependent formation of pre-?-HDL was inhibited by the CETP inhibitors torcetrapib and anacetrapib, it was not reduced by the CETP modulator dalcetrapib. This finding was elucidated using this technique. PMID:21971713

Dernick, Gregor; Obermuller, Stefan; Mangold, Cyrill; Magg, Christine; Matile, Hugues; Gutmann, Oliver; von der Mark, Elisabeth; Handschin, Corinne; Maugeais, Cyrille; Niesor, Eric J.

2011-01-01

91

Chromatography  

NSDL National Science Digital Library

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators covers background information on the basic types of chromatography and has the student separate pigments extracted from pens and plant leaves using paper chromatography. The lesson includes the materials needed and the demonstration procedures.

Keirle, Matt

2012-07-10

92

Characterization of sediment pore-water dissolved organic matter of lakes by high-performance size exclusion chromatography  

Microsoft Academic Search

This paper demonstrates the applicability of high-performance size exclusion chromatography (HPSEC) to characterize lake-sediment pore-water dissolved organic matter (DOM). Two shallow nonstratified Estonian lakes – Harku and Karujärv – were investigated. The HPSEC results for pore waters were compared with those obtained by spectroscopic methods such as fluorescence spectroscopy and UV-absorption, and with other analyses carried out on sediments (sediment

Viia Lepane; Aina Leeben; Olga Malashenko

2004-01-01

93

Characterization of Styrene Copolymers Using Size-Exclusion Chromatography with On-line FT-IR Viscometer Detectors  

Microsoft Academic Search

Size-exclusion chromatography (SEC) provides a rapid method for determining molar mass distributions of macromolecules. In this article, we demonstrate the method of SEC coupled with an on-line Fourier-transform infrared (FT-IR) detector and an on-line differential viscometer developed for copolymer characterization. Using a chemometric technique to analyze the FT-IR spectra allows for determining copolymer concentration and composition. The combination of the

Zengrong Zhang; Rolf Saetre

2007-01-01

94

Analysis of a MIL-L-27502 lubricant from a gas-turbine engine test by size-exclusion chromatography  

NASA Technical Reports Server (NTRS)

Size exclusion chromatography was used to determine the chemical degradation of MIL-L-27502 oil samples from a gas turbine engine test run at a bulk oil temperature of 216 C. Results revealed a progressive loss of primary ester and additive depletion and the formation of higher molecular weight products with time. The high molecular weight products absorbed strongly in the ultraviolet indicating the presence of chromophoric groups.

Jones, W. R., Jr.; Morales, W.

1983-01-01

95

DETERMINATION OF TRACE ANIONS IN WATER BY MULTIDIMENSIONAL ION CHROMATOGRAPHY  

EPA Science Inventory

Selenate, selenite, and arsenate ions were separated from the major anions chloride, nitrate, and sulfate in drinking water, surface water, and groundwater sources by collecting a selected portion of the ion chromatogram, after suppression, on a concentrator column and reinjectin...

96

Chromatography  

NSDL National Science Digital Library

In this activity, explore chromatography and the various colors that make up the ink in markers. Use this activity to investigate cohesion and adhesion. The online version of this activity is set up so that learners solve a mystery.

Boston, Wgbh

2002-01-01

97

Analysis of fluoride in rain water comparison of capillary electrophoresis with ion chromatography and ion-selective electrode potentiometry  

Microsoft Academic Search

Fluoride concentrations in Dutch rain water samples were determined by three different analytical techniques, i.e., (i) capillary electrophoresis (CE), (ii) ion chromatography (IC) and (iii) ion-selective electrode potentiometry (ISE). Performance characteristics in terms of precision, limit of detection and run time have been obtained for the three applied methods using standard solutions in the range of 0.5 to 10.0 ?mol

Marc A. G. T van den Hoop; Rob F. M. J Cleven; Johannes J van Staden; Jos Neele

1996-01-01

98

Single-step isolation of extracellular vesicles by size-exclusion chromatography  

PubMed Central

Background Isolation of extracellular vesicles from plasma is a challenge due to the presence of proteins and lipoproteins. Isolation of vesicles using differential centrifugation or density-gradient ultracentrifugation results in co-isolation of contaminants such as protein aggregates and incomplete separation of vesicles from lipoproteins, respectively. Aim To develop a single-step protocol to isolate vesicles from human body fluids. Methods Platelet-free supernatant, derived from platelet concentrates, was loaded on a sepharose CL-2B column to perform size-exclusion chromatography (SEC; n=3). Fractions were collected and analysed by nanoparticle tracking analysis, resistive pulse sensing, flow cytometry and transmission electron microscopy. The concentrations of high-density lipoprotein cholesterol (HDL) and protein were measured in each fraction. Results Fractions 9–12 contained the highest concentrations of particles larger than 70 nm and platelet-derived vesicles (46%±6 and 61%±2 of totals present in all collected fractions, respectively), but less than 5% of HDL and less than 1% of protein (4.8%±1 and 0.65%±0.3, respectively). HDL was present mainly in fractions 18–20 (32%±2 of total), and protein in fractions 19–21 (36%±2 of total). Compared to the starting material, recovery of platelet-derived vesicles was 43%±23 in fractions 9–12, with an 8-fold and 70-fold enrichment compared to HDL and protein. Conclusions SEC efficiently isolates extracellular vesicles with a diameter larger than 70 nm from platelet-free supernatant of platelet concentrates. Application SEC will improve studies on the dimensional, structural and functional properties of extracellular vesicles.

Boing, Anita N.; van der Pol, Edwin; Grootemaat, Anita E.; Coumans, Frank A. W.; Sturk, Auguste; Nieuwland, Rienk

2014-01-01

99

Study of the degradation of gelatin in paper upon aging using aqueous size-exclusion chromatography.  

PubMed

We studied the aging behaviour of gelatin used to size paper. Thus far, research on the aging of paper has largely ignored the sizing agent. Degradation of the protein was characterised and the impact of paper components, such as cellulose, and aluminium potassium sulphate was evaluated. Whatman No. 1 filter papers sized with two types of gelatins (A and B) were prepared as model samples. Commercially sized modern papers (Arches) were also studied in order to compare laboratory samples with real artist papers. Both types of papers were artificially aged (80 degrees C, 50% relative humidity for 35 and 94 days). Historic papers were included in the study in order to compare artificially aged with naturally aged gelatin. The aqueous extracts from the papers were characterised by aqueous size-exclusion chromatography (SEC) using four PL-Aquagel-OH columns and UV photodiode array detection at 220, 254 and 280 nm. Results showed that gelatin undergoes hydrolysis upon aging, type A gelatin showing a faster degradation rate than type B. The result was an increase in the lower-molar-mass fractions, under 50,000 g mol(-1), and especially in a characteristic fraction with a peak molecular mass (MP) of 14,000 g mol(-1). A significant decrease in the extraction yields of alpha-, beta- and gamma-chains occurred after aging. This was attributed to crosslinking, leading to the formation of less-soluble polypeptides with very high molar mass (>800,000 g mol(-1)) Less than 10% alum had no impact on the degradation rate; higher alum contents accelerated hydrolysis reactions. PMID:11990984

Dupont, Anne-Laurence

2002-03-15

100

Separation of basic oligopeptides by ion-pairing reversed-phase chromatography  

NASA Astrophysics Data System (ADS)

The present thesis consist of five chapters. Chapter I introduces background information on the ion-pairing reversed-phase chromatography and liquid chromatography in the critical condition. Chapter II decribes our study on the isocratic separation of oligolysine (dp = 2 to 8) using a fixed content of acetonitrile (ACN) (23%) and different concentrations of HFBA in the mobile phase (0.6-30.6 mM) on a Waters XBridge Shield RP18® column. We found that the retention time of oligolysine increases as the dp increases, because of an increased number of HFBA bound to the peptides. Furthermore, when [HFBA] increased, the retention time increased at different rates. The greater the dp, the faster the rate. Based on a closed pairing model that presumes an equilibrium between an unpaired state and the paired state with a fixed number of HFBA molecules, an equation was derived for the retention factor of oligolysine. In Chapter III, we compare retention behaviors of oligolysine (dp = 2 to 8) and oligoarginine (dp = 2 to 8) when they are separated on the Waters XBridge Shield RP18® using fixed a ACN content (23%) and difference concentrations of HFBA (0.4-30.6 mM) in the mobile phase. The retention time of oligoarginine also increased at different rates as [HFBA] increased. The greater the dp, the faster the rate. The retention time of oligolysine is shorter than that of oligarginine having the dame dp. We applied Eq.1 to analyze the plot of ln k as a function of [HFBA] for each oligopeptide component to obtain the values for n, Kip,m, and ?Kd,ip. For oligolysine, n increases linearly as dp increase and oligoarginine exhibits an accelerated increase in n as dp rises. The plot of ln ?Kd,ip against dp followed a linear relationship for both peptides. In Chapter IV, we study the effect of mobile phase composition on the retention of oligolysine (dp = 2 to 8) on the Waters XBridge Shield RP18 ®. The ACN content was changed from 20% to 33% and the HFBA concentration from 0.7 to 38.4 mM. We investigated the effect of [HFBA] and percentage of ACN on the resolution in separating the peptides and determined the optimal mobile phase composition. We applied Eq.1 to fit the plot of ln k as a function of [HFBA] for each ACN content, which provided us values for n, Kip,m, and ? Kd,ip. n. We found that ? KD,ip decreases as the ACN content increases and the decrease slows down as the percentage of ACN increases, possibly caused by ACN enrichment in the stationary phase. The study described in Chapter V used a different column, SuperAW 3000 ®, to separate an oligolysine mixture (dp = 3 to 11) in different separation modes including ion exchange, size exclusion, critical condition and reversed phase. The analysis was carried on the SuperAW 3000® column with heptafluorobutyric acid (HFBA) as an ion-pairing reagent. We changed either the percentage of ACN at a fixed concentration of HFBA or the concentration of HFBA at a fixed percentage of ACN to investigate the effects of the percentages ACN and HFBA on the retention of oligolysine in different separation modes. A low molecular weight polyethylene glycol and a low molecular weight polypropylene glycol was used as references in different conditions. We compared the reversed-phase separation on Xbridge Shield ® and SuperAW 3000®, at different concentrations of HFBA. We also found that both ion-exchange and hydrophobic interaction play a role in the separation of oligolysine on SuperAW 3000®, when [HFBA] was low. (Abstract shortened by UMI.).

Xie, Wenchun

101

Multifunctional ion-exchange stationary phases for high-performance liguid chromatography  

Microsoft Academic Search

The preparation and properties of multifunctional ion-exchangers, including one cation and two zwitterion types, for high-performance liquid chromatography (HPLC) are described. These ion-exchange stationary phases (IXSPs) were synthesized through two major steps; first by bonding the corresponding organic moieties, either undecenoic acid, aniline or ethyl p-fluorobenzoate, onto silica surfaces with appropriate silane coupling agents. The bonded silica was subsequently derivatized

Mei-Hui Yang; Kuo-Chang Chang; Jer-Yann Lin

1996-01-01

102

Retention behaviours and separation of carboxylic acids by ion-exchange chromatography  

Microsoft Academic Search

The use of high-performance suppressed ion chromatography for the separation of aliphatic carboxylic acids has become an attractive and viable method during the past years. This paper summarises and critically concludes that some new results have been achieved in separation and detection of low-molecular-mass organic anions. Theoretical and practical considerations of ion-exchange selectivity to control retention behaviour are presented. The

Peter Hajós; L??via Nagy

1998-01-01

103

Determination of eight synthetic food colorants in drinks by high-performance ion chromatography.  

PubMed

Eight synthetic food colorants (Amaranth, Brilliant Blue, Indigo Carmine, New Red, Ponceau 4R, Sunset Yellow, Tartrazine, Allura Red) were determined by high-performance ion chromatography on an anion-exchange analytical column with very low hydrophobicity and visible absorbance detection. Gradient elution with hydrochloric acid-acetonitrile effected both the chromatographic separation of these colorants and the on-line clean-up of the analytical column, which was very advantageous for routine analysis. High-performance ion chromatography may be a solution to the chromatographic analysis for some water-soluble, organic analytes with strong hydrophobicity. The method has been applied to the determination of colorants in drinks and in instant drink powder. No time-consuming pretreatment, as used in conventional liquid chromatography, was needed. PMID:9894346

Chen, Q C; Mou, S F; Hou, X P; Riviello, J M; Ni, Z M

1998-12-01

104

Separation of Fexofenadine, Pseudoephedrine, Potential Impurities, and Degradation Products Using Ion Interaction Chromatography  

Microsoft Academic Search

Ion interaction chromatography has been demonstrated to be a viable separation scheme for a wide variety of small molecules. This separation mechanism has been shown to be effective for a complex mixture of analytes that range from uncharged to positively and\\/or negatively charged. The analytes present in fexofenadine?D tablets are either uncharged or cationic. Therefore, if a single HPLC method

Thomas A. Walker; Gary L. Schmitt

2006-01-01

105

GE Healthcare Data File 11-0025-76 AB Ion exchange chromatography  

E-print Network

GE Healthcare Data File 11-0025-76 AB Ion exchange chromatography Capto Q Figure 1. Capto Q-effective processing with smaller unit operations Media characteristics High throughput in downstream purification requires separation media that combine mechanical strength of the matrix with a pore structure that allows

Lebendiker, Mario

106

Detection of phosphorus oxyanions in synthetic geothermal water using ion chromatography–mass spectrometry techniques  

Microsoft Academic Search

Recent developments in microbiology suggest that reduced inorganic phosphorus oxyanions, including hypophosphite and phosphite, may be present in nature. These studies have inspired the development of specific and sensitive methods that detect phosphorus oxyanions in natural water. This paper will discuss a new technique that couples suppressed conductivity ion chromatography (Dionex AS17 analytical column and potassium hydroxide eluent) with electrospray

Michelle M. Ivey; Krishna L. Foster

2005-01-01

107

Method to Determine Oxalate in High-Level Sludge by Ion Chromatography  

SciTech Connect

The Sludge Batch 3 macrobatch feed to the DWPF is expected to contain a relatively high concentration of oxalate. A simple acid addition at room temperature has been shown to be in high-level sludge. This sample preparation requires only about five minutes and yields solutions suitable for oxalate determinations by ion chromatography.

Coleman, C.J.

2002-12-19

108

Separation and simultaneous determination of four artificial sweeteners in food and beverages by ion chromatography  

Microsoft Academic Search

In this paper, the separation and determination of four artificial sweeteners (aspartame, sodium cyclamate, acesulfame-K and sodium saccharin) by ion chromatography coupled with suppressed conductivity detector is reported. The four artificial sweeteners were separated using KOH eluent generator. Due to the use of eluent generator, very low conductance background conductivity can be obtained and sensitivity of sweeteners has been greatly

Yan Zhu; Yingying Guo; Mingli Ye; Frits S. James

2005-01-01

109

Human Plasma Proteome Analysis by Multidimensional Chromatography Prefractionation and Linear Ion Trap Mass  

E-print Network

Human Plasma Proteome Analysis by Multidimensional Chromatography Prefractionation and Linear Ion,*, and Rong Zeng*, Research Center for Proteome Analysis, Key Lab of Proteomics, Institute of Biochemistry proteome has occurred in recent years because it holds great promise of revolution in disease diagnosis

Tian, Weidong

110

Size exclusion chromatography on soft and semi-rigid packing materials in the dynamic axial compression mode.  

PubMed

The effect of dynamic axial compression within a range of up to 5 bar upon the structure of the bed packed with soft and semi-rigid packing materials (Sephadex G-25, Bio-Gel P2 and Toyopearl HW-40) and the associated chromatographic parameters were studied for size exclusion chromatography. Continuous packing compression is accomplished by use of a special column with controlled external pressure applied to the packing. Compression has been shown to favor an overall increase in the resolution with pressure optima observed in some cases. PMID:12915005

Baru, M B; Danilov, A V; Vagenina, I V

2003-08-29

111

Chromatography  

NSDL National Science Digital Library

In this chemistry activity, learners will separate a mixture of FD&C dyes (colors certified and allowed by the US for the Food, Pharmaceutical, Cosmetics & Personal Care industry) to practice chromatography, a separation technique for mixtures. Learners will record their observations on a data table and note trends. This resource includes questions for learners and instructions for preparing the colors from M&Ms, Orange Kool-Aid, and food coloring.

House, The S.

2014-01-28

112

Determination of polyacrylamides in coal washery effluents by ultrafiltration/site-exclusion chromatography-ultraviolet detection techniques  

SciTech Connect

The use of a combined technique of ultrafiltration and aqueous size-exclusion high-performance liquid chromatography-UV detection for monitoring trace levels of residual polyacrylamide flocculants in coal washery process water is described. Flocculants of both anionic and non-ionic types in effluents are analyzed by chromatography on a TSK 5000 PW type hydrophilic and semirigid porous polymer gel with 0.05 M Na/sub 2/SO/sub 4/ in water as the mobile phase and by UV detection at 208-nm wavelength for detection. Precision studies gave a relative standard deviation of 5.8% and a precision of 2.2% at the 95% confidence level in the concentration range of 20 ppm. The lower limit of detection for the method is 1.0 ..mu..g. Prior to chromatography, fractionation and concentration of the polyacrylamide in effluents are achieved by ultrafiltration with a hollow fiber cartridge having a nominal molecular weight cutoff of 100,000, and recoveries are determined by spiking studies. The application of the techniques for the analysis of residual flocculant in a coal washery thickener feed effluent sample is described.

Leung, R.W.M.; Pandey, R.N.; Das, B.S.

1987-05-01

113

P R O D U C T N O T E Size Exclusion Chromatography Sorbents  

E-print Network

distribution BioSepra Ultrogel AcA sorbents from Pall® are a range of composite sorbents for size exclusion of Ultrogel AcA, this sorbent provides excellent separation efficiency, demonstrated by the low HETP (Height

Lebendiker, Mario

114

Protein losses in ion-exchange and hydrophobic interaction high-performance liquid chromatography  

SciTech Connect

Protein losses in ion-exchange and hydrophobic interaction HPLC were examined. The supports were allnon-porous, packed in columns of identical dimensions. Two ion-exchange chromatography (IEC), anion and cation, as well as a hydrophobic interaction chromatography (HIC) columns were tested. Proteins included cytochrome c, bovine serum albumin (BSA), immunoglobulin G and fibrinogen. Temperature effects on HIC supports were studied for cytochrome c and BSA. Both retention times and recoveries of the proteins were measured. The influence of column residence time on the recovery of proteins were also investigated. We found a linear relationship between the amount of protein recovered and the log of the molecular mass. Retention times also generally increased with temperature for both HIC and IEC. Other trends in retention behavior and recoveries are discussed.

Goheen, Steven C.; Gibbins, Betty M.

2000-01-01

115

Determination of tertiary butylhydroquinone in edible vegetable oil by liquid chromatography\\/ion trap mass spectrometry  

Microsoft Academic Search

A simple, sensitive and accurate analytical method for quantification of tertiary butylhydroquinone (TBHQ) in edible vegetable oil was established by liquid chromatography\\/ion trap mass spectrometry (LC\\/ITMS). After extraction, 5?l of the extracts was directly injected into LC\\/ITMS for TBHQ determination. Ethanol was selected as the extraction solvent. The optimized fragmentation amplitude was 1.70V and electrospray ionization (ESI) was more suitable

Peng-Peng Hao; Jin-Ren Ni; Wei-Ling Sun; Wen Huang

2007-01-01

116

Determination of eight synthetic food colorants in drinks by high-performance ion chromatography  

Microsoft Academic Search

Eight synthetic food colorants (Amaranth, Brilliant Blue, Indigo Carmine, New Red, Ponceau 4R, Sunset Yellow, Tartrazine, Allura Red) were determined by high-performance ion chromatography on an anion-exchange analytical column with very low hydrophobicity and visible absorbance detection. Gradient elution with hydrochloric acid–acetonitrile effected both the chromatographic separation of these colorants and the on-line clean-up of the analytical column, which was

Qing-chuan Chen; Shi-fen Mou; Xiao-ping Hou; J. M Riviello; Zhe-ming Ni

1998-01-01

117

Detection of hypophosphite, phosphite, and orthophosphate in natural geothermal water by ion chromatography  

Microsoft Academic Search

Current doctrine states that phosphorus is incorporated into cells in the pentavalent(V) oxidation state as orthophosphate. However, recent studies show that microorganisms contain enzymes used to metabolize reduced forms of phosphorous, including phosphite(III) and hypophosphite(I), which suggests that there is a natural source for these chemical species. This paper will discuss suppressed conductivity ion chromatography methods developed to detect hypophosphite,

Monica M McDowell; Michelle M Ivey; Mary E Lee; Verena V. V. D Firpo; Tina M Salmassi; Crist S Khachikian; Krishna L Foster

2004-01-01

118

Differentiation of the halogen content of peat samples using ion chromatography after combustion (TX\\/TOXIC)  

Microsoft Academic Search

The proposed method for the differential AOX analysis of water samples was tested for its applicability to differentiate the halogen content of peat samples. For determination of the total and the total organic-bound chlorine, bromine and iodine, peat samples were combusted, and the combustion gases trapped and analyzed by ion chromatography (TX\\/TOX-IC). The total and the organically bound chlorine, bromine

Anke Putschew; Frank Keppler; Martin Jekel

2003-01-01

119

Analysis of radioactive waste samples by ion chromatography-ICP\\/MS  

Microsoft Academic Search

A comprehensive ion chromatography (IC) with beta-counting (beta) and inductively coupled plasma mass spectrometry (ICP\\/MS) detection approach has been developed to separate and detect 20 radionuclides in a Hanford waste tank sample. The IC separation was performed using a multi-functional group (anion\\/cation) resin and eluents of oxalic acid, diglycolic acid, and hydrochloric acid. Shorter-lived radionuclides were detected by a solid-state

O. T. Farmer; J. H. Reeves; E. J. Wyse; C. J. Clemeston; C. J. Barinaga; M. R. Smith; D. W. Koppenaal

1994-01-01

120

Matrix diversion methods for improved analysis of perchlorate by suppressed ion chromatography and conductivity detection.  

PubMed

Two inline matrix diversion methods were developed for the sensitive analysis of perchlorate in a matrix comprising up to 1000 mg l(-1) of chloride, sulfate and bicarbonate ions using suppressed ion chromatography and conductivity detection. The first method used a cryptand C1 concentrator column, which exhibited a high selectivity for perchlorate ion over the other matrix anions. After retaining the sample anions in a concentrator column derivatized with a crytpand phase, a rinse step was implemented with a weak base to divert the matrix ions to waste while selectively retaining perchlorate in the concentrator column for subsequent analysis. The analysis was done using a 2mm IonPac AS16 or 2 mm IonPac AS20 separator column. The second method was a two-dimensional matrix diversion method with a focus on improving the detection sensitivity. The first dimension was used to achieve some resolution of the matrix ions from perchlorate. The perchlorate ion was then diverted into a concentrator column for subsequent analysis in the second dimension. By pursuing analysis using a 4mm IonPac AS16 or IonPac AS20 column in the first dimension and subsequently pursuing analysis using a 2mm IonPac AS16 or IonPac AS20 column format, excellent sensitivities were achieved when the first and second dimensions were operated at the same linear flow velocity (cm min(-1)). While sensitive detection of perchlorate in the low microg l(-1) regime was achieved by the above methods in the presence of matrix ions, superior recovery for perchlorate was demonstrated under a variety of matrix concentrations by the second method. PMID:17723390

Lin, Rong; De Borba, Brian; Srinivasan, Kannan; Woodruff, Andy; Pohl, Chris

2006-05-10

121

Ion chromatography as a measurement device in continuous flow analysis of ice cores  

NASA Astrophysics Data System (ADS)

Melter-based continuous chemical analysis of ice cores has been increasingly employed in ice core research for fast, high resolution measurements of the chemical impurities in snow and ice. In continuous flow analysis (CFA), a heated melter generates uncontaminated flowing streams of ice core meltwater which are channeled directly into measurement devices, such as spectrophotometers, mass spectrometers and flow injection analyzers. These devices essentially serve as on-line and quantitative detectors for the melter-generated flow streams. Ion chromatography (IC) has been the preferred analytical technique for the determination of major chemical impurities in ice cores. Using IC as the measurement or detection technique for continuous flow melter analysis would provide an analytical system for measurement of all major chemical impurities in ice cores. We have constructed such a system by interfacing an ice core melter with several ion chromatographs. This technique (CFA-IC) takes advantage of the fast sample preparation and sub-sampling speed provided by a melter and the all-ion capability with low detection limits of ion chromatography. Initial testing and ice core analysis demonstrate that the CFA-IC technique is capable of (1) measuring all major ions, (2) high analysis speed as a result of reduced sample preparation time, and (3) high temporal resolution while requiring less ice than the conventional discrete sampling method.

Budner, D. M.; Cole-Dai, J.; Ferris, D.

2005-12-01

122

imagination at work Data file 29-0452-69AA Size exclusion chromatography  

E-print Network

to the chromatography medium and the buffer composition has no direct effect on resolution (the degree of separation the separation. SEC is an excellent technique for discriminating between monomer, oligomer, and aggregated forms-term) Temperature stability 4°C to 40°C Working and storage temperature 4°C to 30°C Matrix Composite of cross

Lebendiker, Mario

123

Size Exclusion Chromatography: An Experiment for High School and Community College Chemistry and Biotechnology Laboratory Programs  

ERIC Educational Resources Information Center

A simple multiday laboratory exercise suitable for use in a high school or community college chemistry course or a biotechnology advanced placement biology course is described. In this experiment students gain experience in the use of column chromatography as a tool for the separation and characterization of biomolecules, thus expanding their…

Brunauer, Linda S.; Davis, Kathryn K.

2008-01-01

124

Improved size exclusion chromatography of coal derived materials using N-methyl-2-pyrolidinone as mobile phase  

SciTech Connect

A detailed knowledge of the molecular mass distribution (MMD) in coal and its derived products is essential for a fundamental understanding of coal structure, and of the processes occurring during pyrolyis, liquefaction and combustion. In size exclusion chromatography (SEC) tetrahydrofuran (THF) is commonly employed as the mobile phase. However, THF has limited solvating power and consequently a significant proportion of such materials goes undetected. By comparison, N-methyl-2-pyrolidinone is capable of solvating more of the coal sample and therefore gives the opportunity to determine an improved MMD. In this contribution the extended capabilities of NRP as the mobile phase are demonstrated by analysis of the solutions from solvent fractionation of a coal tar pitch, by SEC using UV/V is absorption, fluorescence and differential refractive index detection. Further application to other coal derived materials appears to indicate that separation is by a substantially size-dependent mechanism.

Johnson, B.R.; Bartle, K.D.; Mitchell, S.C. [Univ. of London (United Kingdom)] [and others

1995-12-31

125

Determination of pore size distributions in capillary-channeled polymer fiber stationary phases by inverse size-exclusion chromatography and implications for fast protein separations.  

PubMed

Capillary-channeled polymer (C-CP) fibers have been utilized as liquid chromatography stationary phases, primarily for biomacromolecule separations on the analytical and preparative scales. The collinear packing of the eight-channeled C-CP fibers provides for very efficient flow, allowing operation at high linear velocity (u>100mm s(-1)) and low backpressure (<2000psi) in analytical-scale separations. To take advantage of these fluid transport properties, there must not be mass transfer limitations as would be imposed by having an appreciably porous phase, wherein solute diffusion limits the overall mass transport rates. To better understand the physical nano-/micro- structure of C-CP fibers, inverse size exclusion chromatography (iSEC) has been employed to determine the pore size distribution (PSD) within C-CP fibers. A diversity of test species (from metal ions to large proteins) was used as probes under non-retaining conditions to obtain a response curve reflecting the apparent partition coefficient (Kd) versus hydrodynamic radii (rm). A mean pore radius (rp) of 4.2nm with standard deviation (sp) of ±1.1nm was calculated by fitting the Kd versus rm data to model equations with a Gaussian pore size distribution, and a pore radius of 4.0±0.1nm was calculated based on a log-normal distribution. The derived mean pore radius is much smaller than traditional support materials, with the standard deviation showing a relatively uniform pore distribution. van Deemter plots were analyzed to provide practical confirmation of the structural implications. Large molecules (e.g., proteins) that are fully excluded from pores have no significant C-terms in the van Deemter plots whereas small molecules that can access the pore volumes display appreciable C-terms, as expected. Fitting of retention data to the Knox equation suggests that the columns operate with a characteristic particle diameter (dp) of ?53?m. PMID:24877979

Wang, Zhengxin; Marcus, R Kenneth

2014-07-18

126

Characterization of stable aluminium-citrate species as reference substances for aluminium speciation by ion chromatography.  

PubMed

Well-defined anionic aluminium-citrate species are accessible from crystalline aluminium complexes. The solution chemistry of those species can be investigated using ion chromatography as a powerful tool for aluminium speciation in aqueous samples. The separation of three anionic aluminium-citrate complexes by anion exchange chromatography is possible within 5 min using isocratic conditions. The element specific detection was done by online coupled ICP-AES. The remaining charge of the complexes after dissolution can be determined by ion chromatography using a retention model. Time-dependent monitoring of the species distribution gave information about the species stabilities and the decomposition pathways. With citric acid as an aluminium chelator partially very stable anionic species are observed. These complexes are important components in biological systems. An example for the practical use of the separation method and the well-defined standards is given for plant sap, which showed two species with similar behavior compared to the investigated stable aluminium-citrate complexes. PMID:16448659

Happel, Oliver; Seubert, Andreas

2006-03-01

127

Development of capillary size exclusion chromatography for the analysis of monoclonal antibody fragments extracted from human vitreous humor.  

PubMed

Recombinant antigen-binding fragments (Fabs) are currently on the market and in development for the treatment of ophthalmologic indications. Recently, Quality by Design (QbD) initiatives have been implemented that emphasize understanding the relationship between quality attributes of the product and their impact on safety and efficacy. In particular, changes in product quality once the protein is administered to the patient are of particular interest. Knowledge of protein aggregation in vivo is of importance due to the possibility of antibody aggregates eliciting an immunogenic response in the patient. Presently, there are few analytical methods with adequate sensitivity to analyze Fab aggregates in human vitreous humor (HVH) because the Fab amount available for analysis is often quite low. Here, we report the development of a highly sensitive capillary size exclusion chromatography (SEC) methodology for Fab aggregate analysis in HVH. We demonstrate a process to perform capillary SEC to analyze Fabs with picogram sensitivity and an RSD of less than 8% for the relative peak area of high molecular weight species (HMWS). In addition, we have developed a Protein G affinity chromatography method to capture Fabs from HVH for capillary SEC analysis. Recovery efficiencies ranging from 86 to 99% were achieved using this recovery method with 300 ?L HVH samples containing Fab1. Finally, we demonstrate the applicability of the methodology by quantifying Fab aggregates in HVH, which can potentially be used for aggregate analysis of clinically relevant samples. PMID:23177154

Rea, Jennifer C; Lou, Yun; Cuzzi, Joel; Hu, Yuhua; de Jong, Isabella; Wang, Yajun Jennifer; Farnan, Dell

2012-12-28

128

Size exclusion and anion exchange high performance liquid chromatography for characterizing metals bound to marine dissolved organic matter.  

PubMed

Size exclusion chromatography (SEC) followed by anion exchange chromatography (AEC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) was applied for fractionating metals bound to marine dissolved organic matter (DOM). Surface seawater samples (100 L) were subjected to tangential flow ultrafiltration (10,000 Da cut off) for isolating and pre-concentrating dissolved large molecules. The isolated fraction (retentate) consisted of 1L, which was further freeze-dried and re-dissolved to 250 mL with ultrapure water. After HI Trap desalting of the re-dissolved retentate, SEC with UV detection showed marine DOM ranging from 6.5 kDa (lower than the permeable volume of the SEC column) to 16 kDa. A further characterization of this fraction by AEC with UV detection revealed the existence of four groups of macromolecules exhibiting retention times of 2.3, 2.8, 4.5 and 14.0 min. AEC hyphenated with ICP-MS showed the presence of strontium and zinc in the first AE fraction isolated from the SEC fraction; while manganese was found to be bound to the second AE fraction. Cobalt was found to be bound to molecules comprising the third AE fraction. PMID:23265737

García-Otero, Natalia; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

2013-01-14

129

Simple purification (desalting) procedure to facilitate structural analysis of an alkali-solubilized/neutralized starch solution by intermediate-pressure size-exclusion chromatography.  

PubMed

A technique was established to remove impurities (e.g., salts) from starch dissolved in strong alkali and neutralized with acid to accommodate starch structural analysis via intermediate-pressure size-exclusion chromatography (IPSEC). Starch (corn and wheat) subjected to an alkaline-microwave dissolution scheme (35 s microwave heating in a mixture of 6 M urea and 1 M KOH) was either treated with ion-exchange resin or passed through a desalting column to remove salt/urea contaminants. Control (untreated) starch solution analyzed by IPSEC displayed a significant interfering peak (attributable to salt/urea), which coeluted with the starch amylose peak. The interfering peak was most efficiently eliminated by first passing the starch solution through a desalting column, which process effectively removed impurities (e.g., salts/urea) without appearing to adversely impact the starch structural analysis. This simple technique coupled with the rapid alkaline-microwave starch dissolution procedure greatly expedites structural investigation of starch by facilitating analysis by IPSEC. PMID:17530769

Kim, Hyun-Seok; Huber, Kerry C

2007-06-27

130

Behavior of the Inadvertent pH Transient Formed by a Salt Gradient in the Ion-Exchange Chromatography of Proteins  

E-print Network

-Exchange Chromatography of Proteins Jessica Soto Pe´rez and Douglas D. Frey* Department of Chemical and Biochemical produced when a stepwise change in salt concentration is used as the eluent in ion-exchange chromatography

Frey, Douglas D.

131

Separation and characterisation of beta2-microglobulin folding conformers by ion-exchange liquid chromatography and ion-exchange liquid chromatography-mass spectrometry.  

PubMed

In this work we present for the first time the use of ion-exchange liquid chromatography to separate the native form and a partially structured intermediate of the folding of the amyloidogenic protein beta2-microglobulin. Using a strong anion-exchange column that accounts for the differences in charge exposure of the two conformers, a LC-UV method is initially optimised in terms of mobile phase pH, composition and temperature. The preferred mobile phase conditions that afford useful information were found to be 35 mM ammonium formate, pH 7.4 at 25°C. The dynamic equilibrium of the two species is demonstrated upon increasing the concentration of acetonitrile in the protein sample. Then, the chromatographic method is transferred to MS detection and the respective charge state distributions of the separated conformers are identified. The LC-MS results demonstrate that one of the conformers is partially unfolded, compared with the native and more compact species. The correspondence with previous results obtained in free solution by capillary electrophoresis suggest that strong ion exchange LC-MS does not alter beta2-microglobulin conformation and maintains the dynamic equilibrium already observed between the native protein and its folding intermediate. PMID:23522119

Bertoletti, Laura; Regazzoni, Luca; Aldini, Giancarlo; Colombo, Raffaella; Abballe, Franco; Caccialanza, Gabriele; De Lorenzi, Ersilia

2013-04-10

132

High-capacity cation-exchange column for enhanced resolution of adjacent peaks of cations in ion chromatography.  

PubMed

One of the advantages of ion chromatography [Anal Chem. 47 (1975) 1801] as compared to other analytical techniques is that several ions may be analyzed simultaneously. One of the most important contributions of cation-exchange chromatography is its sensitivity to ammonium ion, which is difficult to analyze by other techniques [J. Weiss, in: E.L. Johnson (Ed.), Handbook of Ion Chromatography, Dionex, Sunnyvale, CA, USA]. The determination of low concentrations of ammonium ion in the presence of high concentrations of sodium poses a challenge in cation-exchange chromatography [J. Weiss, Ion Chromatography, VCH, 2nd Edition, Weinheim, 1995], as both cations have similar selectivities for the common stationary phases containing either sulfonate or carboxylate functional groups. The task was to develop a new cation-exchange stationary phase (for diverse concentration ratios of adjacent peaks) to overcome limitations experienced in previous trails. Various cation-exchange capacities and column body formats were investigated to optimize this application and others. The advantages and disadvantages of two carboxylic acid columns of different cation-exchange capacities and different column formats will be discussed. PMID:11453025

Rey, M A

2001-06-22

133

Silver ion chromatography using solid-phase ex- traction columns packed with a bonded-sulfonic acid phase  

Microsoft Academic Search

Commercial solid-phase extraction columns packed with a stationary phase with bonded benzenesulfonic acid groups are readily converted to the silver ion form and can then be used for silver ion chromatography of lipids. To illustrate the utility of such procedures, methyl ester derivatives of fatty acids with zero to six double bonds were separated from each other by a simple

William W. Christie

134

The glycolate and 2-phosphoglycolate content of tissues measured by ion chromatography coupled to mass spectrometry  

PubMed Central

Glycolate and 2-phosphoglycolate (PG) are 2-carbon monocarboxylic acids with ill-defined metabolic roles. Their concentrati ons have not yet been described in tissues apart from body fluids and erythrocytes. We describe the use of ion chromatography coupled with mass spectrometry (IC-MS) to quantify levels of glycolate and PG in tissue. Sample preparation and analysis can be performed within an hour. Low concentrations of glycolate (12 – 48 nmoles/g) and PG (4 – 17 nmoles/g) were detected in all tissues. The availability of this IC-MS assay will facilitate investigations of the origin, function, and metabolism of glycolate and PG in tissues. PMID:22093610

Knight, John; Hinsdale, Mark; Holmes, Ross

2011-01-01

135

Ion Exchange Chromatography and Mass Spectrometric Methods for Analysis of Cadmium-Phytochelatin (II) Complexes  

PubMed Central

In this study, in vitro formed Cd-phytochelatin (PC2) complexes were characterized using ion exchange chromatography (IEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The ratio of both studied compounds as well as experimental conditions were optimized. The highest yield of the complex was observed under an applied concentration of 100 µg·mL?1 PC2 and 100 µg·mL?1 of CdCl2. The data obtained show that IEC in combination with MALDI-TOF is a reliable and fast method for the determination of these complexes. PMID:23538727

Merlos Rodrigo, Miguel Angel; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

2013-01-01

136

Method for the determination of dissolved chloride, nitrate, and sulfate in natural water using ion chromatography  

USGS Publications Warehouse

Ion chromatography was used for the determination of dissolved chloride, nitrate and sulfate in natural water where concentrations ranged from a detection limit of 0.02 milligrams per liter to 80 milligrams per liter for chloride, to 18 milligrams per liter for nitrate, and to 280 milligrams per liter for sulfate. Specific conductance was the mode of detection used. Three analytical sample size loops of 11, 61, and 250 microliters, were used to include the analytical ranges described. U.S. Geological Survey Standard Reference Water Samples were analyzed to test the precision and accuracy of the analyses.

Brinton, Terry I.; Antweiler, Ronald C.; Taylor, Howard E.

1996-01-01

137

EDTA determination in pharmaceutical formulations and canned foods based on ion chromatography with suppressed conductimetric detection  

Microsoft Academic Search

A novel direct method for the determination of EDTA was developed and validated based on ion chromatography with suppressed conductimetric detection and anion exchange column (Dionex AS-14, 4mm×250mm). Depending on coexisting substances, suitable eluents are 10mM carbonate buffer\\/pH 11.0 or 10.5 (tR,EDTA=5.5 and 9.4min, respectively), and 120mM borate buffer\\/pH 8.5 (tR,EDTA=16.2min). For 10mM carbonate buffer\\/pH 11.0 and isocratic flow rate

A. A. Krokidis; N. C. Megoulas; M. A. Koupparis

2005-01-01

138

Ion exchange chromatography and mass spectrometric methods for analysis of cadmium-phytochelatin (II) complexes.  

PubMed

In this study, in vitro formed Cd-phytochelatin (PC2) complexes were characterized using ion exchange chromatography (IEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The ratio of both studied compounds as well as experimental conditions were optimized. The highest yield of the complex was observed under an applied concentration of 100 µg·mL(-1) PC2 and 100 µg·mL(-1) of CdCl2. The data obtained show that IEC in combination with MALDI-TOF is a reliable and fast method for the determination of these complexes. PMID:23538727

Rodrigo, Miguel Angel Merlos; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

2013-04-01

139

Tailored noise waveform/collision-induced dissociation of ions stored in a linear ion trap combined with liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

A new collision-induced dissociation (CID) technique based on broadband tailored noise waveform (TNW) excitation of ions stored in a linear ion trap has been developed. In comparison with the conventional sustained off-resonance irradiation (SORI) CID method commonly used in Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), this MS/MS technique increases throughput by eliminating the long pump-down delay associated with gas introduction into the high vacuum ICR cell region. In addition, the TNW-CID method speeds spectrum acquisition since it does not require Fourier transformation, calculation of resonant frequencies and generation of the excitation waveforms. We demonstrate TNW-CID coupled with on-line capillary reverse-phase liquid chromatography separations for the identification of peptides. The experimental results are compared with data obtained using conventional quadrupole ion trap MS/MS and SORI-CID MS/MS in an ICR cell. PMID:15487023

Vilkov, Andrey N; Bogdanov, Bogdan; Pasa-Toli?, Ljiljana; Prior, Dave C; Anderson, Gordon A; Masselon, Christophe D; Moore, Ronald J; Smith, Richard D

2004-01-01

140

A new type of metal chelate affinity chromatography using trivalent lanthanide ions for phosphopeptide enrichment.  

PubMed

In this study, a new type of immobilized metal-ion affinity chromatography (IMAC) resin for the isolation of phosphopeptides was synthesized which is based on the specific interaction between phosphate groups and chelated lanthanide metal ions. In this regard trivalent lanthanum, holmium and erbium ions were chelated to a highly porous phosphonate polymer which was prepared by radical polymerization of vinylphosphonic acid (VPA) and divinylbenzene (DVB). The developed method was evaluated with peptide mixtures from digested standard proteins (?-casein, ?-casein and ovalbumin) as well as with bovine milk, egg white and a spiked HeLa cell lysate. Compared to the commonly used TiO2 approach, the presented method showed higher selectivity for phosphorylated peptides. This can be explained by the strong preference of trivalent lanthanide ions for phosphates with which they form very tight ionic bonds. Mono- and multiply phosphorylated peptides could be enriched and released in a single basic elution step, while non-phosphorylated peptides remained on the resin. Ab initio quantum mechanical energy minimizations of model complexes for polymer-ion-ligand interactions provided geometries, binding energies and charges which are discussed in conjunction with the observed experimental properties, leading to the most satisfying agreement. The presented lanthanide-IMAC resins represent promising affinity materials for the selective isolation of phosphopeptides from biological samples. PMID:23552617

Mirza, Munazza R; Rainer, Matthias; Messner, Christoph B; Güzel, Yüksel; Schemeth, Dieter; Stasyk, Taras; Choudhary, Muhammad I; Huber, Lukas A; Rode, Bernd M; Bonn, Günther K

2013-05-21

141

Mixed-bed ion-exchange columns for protein high-performance liquid chromatography.  

PubMed

Protein retention is investigated on high-performance liquid chromatography columns packed with mixtures of ion exchangers. Retention factors are measured at both low and high salt concentrations in the eluent and their dependence on the bed composition is found to be linear in some cases, but non-linear in others. The physical basis for the observed non-linear retention behavior has not been established and an empirical mixing rule is employed to express the dependence of protein retention on bed composition. Protein separations are carried out on the mixed-bed columns by using gradient elution with increasing salt concentration and the process is modelled mathematically. The retention times predicted by computer calculations correspond closely to the experimental findings. Optimal selection of the mixed-bed composition and the gradient steepness for the separation of four proteins is illustrated by using the window diagram technique. Although the experimental results presented here deal with electrostatic interaction chromatography of proteins only the applicability of mixed sorbents is expected to extend to all branches of liquid chromatography. It is anticipated that mixed-sorbent columns will find extensive use in the large-scale purification of biological compounds and in routine analysis. PMID:3243849

Maa, Y F; Antia, F D; el Rassi, Z; Horváth, C

1988-10-28

142

Development of a new suppressor for the ion chromatography of inorganic cations.  

PubMed

This paper reports on a new suppressor that can be used in the ion chromatography (IC) of inorganic cations. The space in which the electrode is set on both sides of the device is separated into three cells using anion- and cation-exchange membranes. Each of the cells is packed with either an anion- or cation-exchange resin. Anions in the eluent and injected sample are removed by electrical regeneration, based on the electrokinetic phenomenon on both the surface of the ion-exchange resins and the membranes. The electrical conductivity of the suppressed eluent reaches a level similar to that of ultrapure water; therefore, a cation detection limit of sub-ppb order is achieved in IC using the device as a suppressor. PMID:24717657

Masunaga, Hiroto; Higo, Yuji; Ishii, Mizuo; Maruyama, Noboru; Yamazaki, Shigeo

2014-01-01

143

Impurity profiling of acetylspiramycin by liquid chromatography-ion trap mass spectrometry.  

PubMed

Investigation of acetylspiramycin (ASPM) and its related substances was carried out using a reversed-phase liquid chromatography/tandem mass spectrometry method. The identification of impurities in the ASPM complex was performed with a quadrupole ion trap mass spectrometer, with an electrospray ionization (ESI) source in the positive ion mode which provides MS(n) capability. A total of 83 compounds were characterized in commercial samples, among which 31 impurities that had never been reported and 31 partially characterized impurities were deduced using the collision-induced dissociation (CID) spectra of major ASPM components as templates. Most of the major impurities arise from the starting materials and the synthesis process. This work provides very useful information for quality control of ASPM and evaluation of its synthesis process. PMID:20843520

Wang, Ming-juan; Pendela, Murali; Hu, Chang-qin; Jin, Shao-hong; Hoogmartens, Jos; Van Schepdael, Ann; Adams, Erwin

2010-10-15

144

Determination of anionic surfactants during wastewater recycling process by ion pair chromatography with suppressed conductivity detection  

NASA Technical Reports Server (NTRS)

A direct approach utilizing ion pairing reversed-phase chromatography coupled with suppressed conductivity detection was developed to monitor biodegradation of anionic surfactants during wastewater recycling through hydroponic plant growth systems and fixed-film bioreactors. Samples of hydroponic nutrient solution and bioreactor effluent with high concentrations (up to 120 mS electrical conductance) of inorganic ions can be analyzed without pretreatment or interference. The presence of non-ionic surfactants did not significantly affect the analysis. Dynamic linear ranges for tested surfactants [Igepon TC-42, ammonium lauryl sulfate, sodium laureth sulfate and sodium alkyl (C10-C16) ether sulfate] were 2 to approximately 500, 1 to approximately 500, 2.5 to approximately 550 and 3.0 to approximately 630 microg/ml, respectively.

Levine, L. H.; Judkins, J. E.; Garland, J. L.; Sager, J. C. (Principal Investigator)

2000-01-01

145

Analysis of nondistillables from coal liquids by size exclusion chromatography/fourier transform infrared spectrometry (SEC/FT-IR)  

SciTech Connect

Coal liquids may contain as much as 50% or more nondistillables. Most of the nondistillable materials are soluble in solvents such as tetrahydrofuran (THF) or pyridine. Currently, the nondistillables are characterized by elemental analysis, nuclear magnetic resonance (NMR), Fourier Transform infrared (FT-IR) spectrometry and heating values. The nondistillable and distillable fractions of a coal liquid can be separated and analyzed by size exclusion chromatography (SEC). SEC separates molecules based on ''linear molecular'' size. The application of SEC is limited only by the solubility of the sample in a solvent. Although SEC has been used primarily for the separation and characterization of polymers based on molecular size or molecular weight, its use has been extended to the separation of smaller size molecules. The separation of coal liquids by SEC is easily achieved with appropriate columns. Because coal-derived mixtures have several components of a similar size, the use of SEC alone is not adequate for the purpose of identification. Gas chromatography (GC) coupled with mass spectrometry (MS) has been used in conjunction with the SEC. Conventional FT-IR techniques are rather unreliable as well as time consuming, because the mass of coal liquid in a SEC fraction is very small. A new technique, which is more reliable and requires less time than the conventional techniques, is developed for the analysis of small samples. The residues from SEC fractions are spotted onto a potassium bromide (KBr) pellet. The spotted samples are then analyzed using a narrow focused beam in the Microbeam accessory of a Nicolet 60 SXR FT-IR spectrometer. The paper discusses the analytical technique as well as the FT-IR spectra of SEC fractions.

Philip, C.V.; Anthony, R.G. (Kinetics, Catalysis and Reaction Engineering Lab., Dept. of Chemical Engineering, Texas A and M Univ., College Station, TX (US))

1988-06-01

146

Determination of perchlorate in infant formula by isotope dilution ion chromatography/tandem mass spectrometry  

PubMed Central

A sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in infant formula. The perchlorate was extracted from infant formula by using 20 ml of methanol and 5 ml of 1% acetic acid. All samples were spiked with 18O4 isotope-labelled perchlorate internal standard prior to extraction. After purification on a graphitised carbon solid-phase extraction column, the extracts were injected into an ion chromatography system equipped with an Ionpac AS20 column for separation of perchlorate from other anions. The presence of perchlorate in samples was quantified by isotope dilution mass spectrometry. Analysis of both perchlorate and its isotope-labelled internal standard was carried out on a Waters Quattro Ultima triple quadrupole mass spectrometer operating in a multiple reaction monitoring (MRM) negative ionisation mode. The method was validated for linearity and range, accuracy, precision, sensitivity, and matrix effects. The limit of quantification (LOQ) was 0.4 ?g 1?1 for liquid infant formula and 0.95 ?g kg?1 for powdered infant formula. The recovery ranged from 94% to 110% with an average of 98%. This method was used to analyse 39 infant formula, and perchlorate concentrations ranging from

Wang, Z.; Lau, B.P.-Y.; Tague, B.; Sparling, M.; Forsyth, D.

2011-01-01

147

Fully automated micro- and nanoscale one- or two-dimensional high-performance liquid chromatography system for liquid chromatography–mass spectrometry compatible with non-volatile salts for ion exchange chromatography  

Microsoft Academic Search

A one- or two-dimensional high performance liquid chromatography system for electrospray ionization mass spectrometers has been developed that is optimized for ion exchange and reversed phase separations. A unique and simple valve configuration permits the use of a variety of non-volatile salts; ammonium sulfate was used in an example of strong cation exchange separations. The system was designed and evaluated

Junichi Masuda; Dawn M. Maynard; Masayuki Nishimura; Teruhisa Ueda; Jeffrey A. Kowalak; Sanford P. Markey

2005-01-01

148

Surface topography of histidine residues: a facile probe by immobilized metal ion affinity chromatography.  

PubMed Central

Immobilized metal ion affinity chromatography (IMAC) has been explored as a probe into the topography of histidyl residues of a protein molecule. An evaluation of the chromatographic behavior of selected model proteins--thioredoxin, ubiquitin, calmodulin, lysozyme, cytochrome c, and myoglobin on immobilized transition metal ions (Co2+, Ni2+, Cu2+, and Zn2+)--allows establishment of the following facets of the histidyl side chain distribution: (i) either interior or surface; (ii) when localized on the surface, accessible or unaccessible for coordination; (iii) single or multiple; (iv) when multiple, either distant or vicinal. Moreover, proteins displaying single histidyl side chains on their surfaces may, in some instances, be resolved by IMAC; apparently, the microenvironments of histidyl residues are sufficiently diverse to result in different affinities for the immobilized metal ions. IMAC, previously introduced as an approach to the fractionation of proteins, has become also, upon closer examination, a facile probe into the topography of histidyl residues. This is possible because of the inherent versatility of IMAC; an appropriate metal ion (M2+) can be selected to suit the analytical purpose and a particular chromatographic protocol can be applied (isocratic pH, falling pH, and imidazole elution). PMID:2538816

Hemdan, E S; Zhao, Y J; Sulkowski, E; Porath, J

1989-01-01

149

[Simultaneous analysis of iodate, iodide, bromate and bromide by ion chromatography with ultraviolet detection].  

PubMed

An analytical method of ion chromatography with ultraviolet detection has been developed and applied for the simultaneous determination of iodate, iodide, bromate and bromide. The separation was performed on a quaternary ammonium type anion exchange column with citric acid and acetonitrile as mobile phase. The effects of the detection wavelength, the kind and concentration of the mobile phase and other parameters on separation and detection of the four ions were investigated. The retention rules were studied and the chromatographic conditions were optimized. Under the conditions of 210 nm as detection wavelength, 0.9 mL/min as flow rate, 40 degrees C as column temperature, and 1.0 mmol/L citric acid-acetonitrile (85:15, v/ v; pH 5.0) as mobile phase, the four ions were completely separated and the system peaks and other common anions didn't interfere with the determination. The detection limits of the four ions (S/N = 3) were 0.07-0.16 mg/L. The relative standard deviations of the retention times and peak areas obtained by determining samples five times continuously were below 1%. The spiked recoveries of the four anions were from 98.0% to 102%. This method has been successfully used to determine ionic liquids synthesized by chemistry laboratory and underground water samples. The results were accurate and reliable. PMID:24984472

Li, Meng; Yu, Hong; Zheng, Xiurong

2014-03-01

150

Electrophoresis and size-exclusion chromatography of humic substances extracted from detritus and soils of different geneses  

NASA Astrophysics Data System (ADS)

Electrophoresis in 10% polyacrylamide gel in the presence of denaturants and size-exclusion chromatography in Sephadex G-75 in 7 M urea were used for the comparative analysis of humic substances isolated from a typical chernozem, soddy-podzolic soil, and chestnut soil and from the easily decomposable organic matter (plant detritus) contained in these soils. After the electrophoresis, the gel with naturally colored bands of humic substances was further stained with a dye specific for proteins by immersing into a solution containing Coomassie Brilliant Blue R-250 and CuSO4. The electrophoretic and chromatographic analyses showed that humic substances from the soils and the corresponding detritus fractions significantly differed in the intensity of the natural color of the electrophoretic fractions, the molecular-weight distribution, and the color of the electrophoretic fractions colored by the protein-specific dye (which was first discovered in this study). The hypothesis of Tyurin and Aleksandrova suggesting that the transformation of humus sources (plant detritus) into humic substances proceeds in the direction from the high-molecular compounds to the low-molecular compounds was experimentally confirmed.

Trubetskaya, O. E.; Trubetskoi, O. A.; Borisov, B. A.; Ganzhara, N. F.

2008-02-01

151

High-pressure size exclusion chromatography analysis of dissolved organic matter isolated by tangential-flow ultra filtration  

USGS Publications Warehouse

A 1,000-Dalton tangential-flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800-Dalton standard. Unaltered and TFUF-fractionated DOM molecular weights were assayed by high-pressure size exclusion chromatography (HPSEC). The weight-averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer-specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton-exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.

Everett, C. R.; Chin, Y. -P.; Aiken, G. R.

1999-01-01

152

A combinatorial approach to studying protein complex composition by employing size-exclusion chromatography and proteome analysis.  

SciTech Connect

The genome sequences of numerous organisms are available now, but gene sequences alone do not provide sufficient information to accurately deduce protein functions. Protein function is largely dependent on the association of multiple polypeptide chains into large structures with interacting subunits that regulate and support each other. Therefore, the mapping of protein interaction networks in a physiological context is conducive to deciphering protein functions, including those of hypothetical proteins. Although several high-throughput methods to globally identify protein interactions have been reported in recent years, these approaches often have a high rate of nonspecific or artificial interactions detected. For instance, the fraction of false positives of the protein interactions identified by yeast two-hybrid assay has been predicted to be of the order of 50%. We have developed a strategy to globally map Bacillus subtilis protein-protein interactions in a physiological context by fractionating the cell lysates using size-exclusion chromatography (SEC), followed by proteome analysis. Components of both known and unknown protein complexes, multisubunits and multiproteins, have been identified using this strategy. In one case, the partners of the B. subtilis protein complex have been coexpressed in Escherichia coli, and the formation of the overexpressed protein complex has been further confirmed by a pull-down assay.

Li, S.; Giometti, C.; Biosciences Division

2007-07-01

153

Structural Evolution of Polylactide Molecular Bottlebrushes: Kinetics Study by Size Exclusion Chromatography, Small Angle Neutron Scattering and Simulations  

SciTech Connect

Structural evolution from poly(lactide) (PLA) macromonomer to resultant PLA molecular bottlebrush during ring opening metathesis polymerization (ROMP) was investigated for the first time by combining size exclusion chromatography (SEC), small-angle neutron scattering (SANS) and coarse-grained molecular dynamics (CG-MD) simulations. Multiple aliquots were collected at various reaction times during ROMP, and subsequently analyzed by SEC and SANS. The two complementary techniques enable the understanding of systematic changes in conversion, molecular weight and dispersity as well as structural details of PLA molecular bottlebrushes. CG-MD simulation not only predicts the experimental observations, but it also provides further insight into the analysis and interpretation of data obtained in SEC and SANS experiments. We find that PLA molecular bottlebrushes undergo three conformational transitions with increasing conversion (i.e., increasing the backbone length): (1) from an elongated to a globular shape due to longer side chain at lower conversion, (2) from a globular to an elongated shape at intermediate conversion caused by excluded volume of PLA side chain, and (3) the saturation of contour length at higher conversion due to chain transfer reactions.

Pickel, Deanna L [ORNL; Kilbey, II, S Michael [ORNL; Uhrig, David [ORNL; Hong, Kunlun [ORNL; Carrillo, Jan-Michael Y [ORNL; Sumpter, Bobby G [ORNL; Ahn, Suk-Kyun [ORNL; Han, Youngkyu [ORNL; Kim, Dr. Tae-Hwan [Korea Atomic Energy Research Institute; Smith, Gregory Scott [ORNL; Do, Changwoo [ORNL

2014-01-01

154

Size exclusion chromatography for the quantitative profiling of the enzyme-catalyzed hydrolysis of Xylo-oligosaccharides.  

PubMed

High-performance size exclusion chromatography (HPSEC) is a widely used method for the qualitative profiling of oligosaccharide mixtures, including, for example, enzymatic hydrolysates of plant biomass materials. A novel method employing HPSEC for the quantitative analytical profiling of the progress of enzymatic hydrolysis of different xylan substrates was developed. The method relies on dividing the HPSEC elution profiles into fixed time intervals and utilizing the linear refractive index response (area under the curve) of defined standard compounds. To obtain optimal HPSEC profiles, the method was designed using 0.1 M CH(3)COONa both in the mobile phase and as the sample solution matrix, after systematic evaluation of the influence of the mobile phase, including the type, ionic strength, and pH, on the refractive index detector response. A time study of the enzyme-catalyzed hydrolysis of birchwood xylan and wheat bran by a Bacillus subtilis XynA xylanase (GH 11) was used as an example to demonstrate the workability of the HPSEC method for obtaining progress curves describing the evolution in the product profile during enzyme catalysis. PMID:19994888

Rasmussen, Louise E; Meyer, Anne S

2010-01-27

155

Improved size exclusion chromatography of coal derived materials using N-methyl-2-pyrrolidinone as mobile phase  

SciTech Connect

A detailed knowledge of the molecular mass distribution (MMD) in coal and its derived products is essential for a fundamental understanding of coal structure, and of the processes occurring during pyrolysis, liquefaction and combustion. Indeed with increased economic and environmental pressure to use natural resources more effectively such knowledge can be applied to gaining more from finite coal reserves. Of the methods available for determining MMDs size exclusion chromatography (SEC) is perhaps the most routinely employed. In SEC tetrahydrofuran (THF) is the most commonly employed mobile phase. However THF has limited solvating power for coal derived materials and consequently a significant proportion of such materials goes undetected. In addition the interpretation of chromatograms with reference to calibration of the column with polystyrene standards is flawed. By comparison, N-methyl-2-pyrrolidinone (NMP) is capable of solvating more of the coal sample and therefore gives the opportunity to determine an improved MMD. In this contribution the extended capabilities of NMP as the mobile phase are demonstrated primarily through the analysis of a coal tar pitch. Both NMP and THF are used as mobile phases for SEC using a number of detection techniques, allowing comparison and evaluation of different chromatographic systems to the analysis of coal derived materials.

Johnson, B.R.; Bartle, K.D. [Univ. of Leeds (United Kingdom); Herod, A.A.; Kandiyoti, R. [Imperial College, London (United Kingdom)

1995-12-31

156

Method for Characterization of Low Molecular Weight Organic Acids in Atmospheric Aerosols Using Ion Chromatography Mass  

E-print Network

Chromatography Mass Spectrometry Lacey C. Brent,* Jessica L. Reiner, Russell R. Dickerson, and Lane C. Sander spectroscopy (FTIR), liquid chromatography with ultraviolet detection (LCUV), or nuclear magnetic resonance chromatography mass spectrometry (GCMS) methods have demonstrated reliable structural identification of water

Dickerson, Russell R.

157

Screening of beta-blockers in human serum by ion-pair chromatography and their identification as methyl or acetyl derivatives by gas chromatography-mass spectrometry.  

PubMed

A simultaneous screening method for atenolol, acebutolol, metoprolol, oxprenolol, alprenolol and propranolol by ion-pair chromatography with a column-switching technique was developed. The serum samples were purified using either liquid-liquid extraction or solid-phase extraction methods. The pretreatment of the samples consisted of hydrolysis and protein precipitation. The drug separation was on either octadecylsilica or polymer-based alkyl column material. Binary eluent mixtures containing methanol and a buffer solution with a quaternary ammonium salt as an ion-pair former were used. Detection of the compounds in liquid chromatographic analysis was based on ultraviolet spectra. The effects of methanol, two buffers and the ion-pair former on the retention of the compounds were studied. The determination limits ranged from nanograms to micrograms in the ion-pair chromatographic method, depending on the drug studied. Identification was based on the mass spectra or, if necessary, on selected-ion monitoring spectra of either the methylated or the acetylated compounds obtained by means of gas chromatography-electron impact or negative chemical ionization mass spectrometry. The detection limits for the identified compounds were in the picogram range. The matrix effect was strong, and this resulted in determination limits in the nanogram range with the scan method. PMID:8095938

Sirén, H; Saarinen, M; Hainari, S; Lukkari, P; Riekkola, M L

1993-02-19

158

Absolute Molecular Weight Distribution of Low-Molecular-Weight Heparins by Size-Exclusion Chromatography with Multiangle Laser Light Scattering Detection  

Microsoft Academic Search

The absolute molecular weight (Mr) distribution of seven low-molecular-weight (LMW) heparin products was determined by size-exclusion chromatography (SEC) coupled with multiangle laser light scattering (MALLS) detection. The SEC\\/MALLS technique does not rely on relativeMrstandards for column calibration and yields absoluteMrestimates directly from the angular dependence of scattered light intensity as a function of concentration, as formulated by light scattering theory.

James E. Knobloch; Patrick N. Shaklee

1997-01-01

159

Ion-exclusion/cation-exchange chromatographic determination of common inorganic ions in human saliva by using an eluent containing zwitterionic surfactant.  

PubMed

Ion-exclusion/cation-exchange chromatography with an eluent containing the bile salt-type zwitterionic surfactant CHAPS was performed in order to evaluate variations in anion (SO(4)(2-), NO(3)(-), and SCN(-)) and cation (Na(+), K(+), NH(4)(+), Mg(2+), and Ca(2+)) concentrations in human saliva. CHAPS prevents the adsorption of proteins to the stationary phase, i.e., weakly acidic cation-exchange resin, since it aggregates proteins without denaturing them. Addition of 1mM CHAPS to the eluent comprising 6mM tartaric acid and 7 mM 18-crown-6 yielded reproducible separations of anions and cations in protein-containing saliva. The resolutions of anions and cations were not significantly affected by the addition of CHAPS to the eluent. The concentrations of Na(+) and K(+) varied before and after meals; or that of SCN(-), upon smoking. The relative standard deviations of peak areas ranged from 0.3 to 5.1% in 1 day (n=20) and from 1.4 to 5.8% over 6 days (n=6). PMID:18992886

Mori, Masanobu; Iwata, Tomotaka; Satori, Tatsuya; Ohira, Shin-Ichi; Itabashi, Hideyuki; Tanaka, Kazuhiko

2008-12-12

160

Evaluation and Quantitation of Intact Wax Esters of Human Meibum by Gas-Liquid Chromatography-Ion Trap Mass Spectrometry  

PubMed Central

Purpose. Wax esters (WE) of human meibum are one of the largest group of meibomian lipids. Their complete characterization on the level of individual intact lipid species has not been completed yet. We obtained detailed structural information on previously uncharacterized meibomian WE. Methods. Intact WE were separated and analyzed by means of high-temperature capillary gas-liquid chromatography (GLC) in combination with low voltage (30 eV) electron ionization ion trap mass spectrometry (ITMS). 3D (mass-to-charge ratio [m/z] versus lipid sample weight versus signal intensity) calibration plots were used for quantitation of WE. Results. We demonstrated that GLC-ITMS was suitable for analyzing unpooled/underivatized WE collected from 14 individual donors. More than 100 of saturated and unsaturated WE (SWE and UWE, respectively) were detected. On average, UWE represented about 82% of the total WE pool. About 90% of UWE were based on oleic acid, while less than 10% were based on palmitoleic acid. The amounts of poly-UWE were <3% of their mono-UWA counterparts. SWE were based primarily on C16–C18 fatty acids (FA) in overall molar ratios of 22:65:13. A pool of C16:0-FA was comprised of a 20:80 (mol/mol) mixture of straight chain and iso-branched isomers, while the corresponding ratio for C18:0-FA was 43:57. Interestingly, C17:0-FA was almost exclusively branched, with anteiso- and iso-isomers found in a ratio of 93:7. Conclusions. GLC-ITMS can be used successfully to analyze more than 100 individual species of meibomian WE, which were shown to comprise 41 ± 8% (wt/wt) of meibum, which made them the largest group of lipids in meibum. PMID:22531701

Butovich, Igor A.; Arciniega, Juan C.; Lu, Hua; Molai, Mike

2012-01-01

161

Determination of sulfur anions in spent oil shale leachates by ion chromatography  

SciTech Connect

The leaching and transport of chemical constituents from spent oil shale disposal areas is an area of environmental concern at the present time. Sulfur-containing compounds are prevalent in spent oil shales and have the potential to leach into aqueous systems surrounding disposal sites. Computer modeling has been used in recent years to predict the transport of species in an aqueous environment. The quality of model predictions, however, depends on the validation steps taken in comparing model predictions with laboratory data on ion speciation. Further, the quality of the validation step depends on the reliability of laboratory methods in generating ion speciation data. The purpose of this study was to develop methods to separate and quantify sulfur-containing anions in spent oil shale leachates by suppressed ion chromatography. The anions studied were S{sup 2{minus}} (sulfide), SO{sup 2{minus}}{sub 3} (sulfite), SO{sup 2{minus}}{sub 4} (sulfate), SCN{sup {minus}} (thiocyanate), S{sub 2}O{sup 2{minus}}{sub 3} (thiosulfate), and S{sub 4}O{sup 2{minus}}{sub 6} (tetrathionate). After the separations were developed, a series of method-challenging experiments were performed to test the reliability of the methods and assure the development of an analytically sound product. 24 refs., 7 figs., 5 tabs.

Niss, N.D.

1989-07-01

162

[Determination of piperidinium ionic liquid cations by ion-pair chromatography-indirect ultraviolet detection].  

PubMed

A method was developed for the determination of piperidinium cations by ion-pair chromatography with indirect ultraviolet detection. Chromatographic separation was performed on a reversed-phase C18 column using background ultraviolet absorption reagent-ion-pair reagent/organic solvent as mobile phase. The effects of the background ultraviolet absorption reagent, detection wavelength, ion-pair reagent, organic solvent, column temperature and flow rate on the determination of piperidinium cations were investigated and the retention rules were studied. The optimized chromatographic conditions for the determination of piperidinium cations were as follows: mobile phase, 0.5 mmol/L 4-aminophenol hydrochloride-0.1 mmol/L 1-heptanesulfonic acid sodium aqueous solution/methanol (80:20, v/v); detection wavelength, 210 nm; column temperature, 30 degrees C; flow rate, 1.0 mL/min. Under these conditions, the three piperidinium cations were baseline separated within 4 min. The detection limits (S/N = 3) of the piperidinium cations were 0.137-0.545 mg/L. The relative standard deviations (n = 5) for peak area and retention time were 0.72% and 0.37% respectively. The method has been successfully applied to the determination of piperidinium cations in ionic liquids synthesized by chemistry laboratory. The recoveries of piperidinium cations after spiking were 97.0%-98.4%. The method is simple, rapid, reproducible, linear, and can meet the quantitative analysis requirement for the determination of piperidinium cations. PMID:25255572

Wang, Miaoyu; Yu, Hong; Li, Ping; Li, Jie; Gao, Yufeng

2014-07-01

163

Gram-scale purification of phosphorothioate oligonucleotides using ion-exchange displacement chromatography.  

PubMed Central

The purification of oligonucleotides by ion-exchange displacement chromatography is demonstrated on the gram-scale. Using a 50 mmD x 100 mmL (203 ml) column operated in the displacement mode, 1.2 g of a 24mer phosphorothioate oligonucleotide was purified. Product yield for this separation was 70% (780 mg) at a purity of 96.4% and the mass balance recovery of all oligonucleotide was 97.5%. The displacement purification of four additional phosphorothioate oligonucleotides ranging in length from 18 to 25 bases is also demonstrated on the semi-preparative (10-50 mg) scale. All of these oligonucleotides were purified using similar displacement conditions and typical results were 60% yield at 96% purity. The displacement portion of these separations required <15 min and total cycle time including equilibration, feed loading and regeneration can be performed in under 30 min. These results seem to indicate that displacement chromatography may be amenable to generalizations in separation protocol that would greatly reduce the effort required to obtain an optimized purification scheme for moderately long oligonucleotides. PMID:7610058

Gerstner, J A; Pedroso, P; Morris, J; Bergot, B J

1995-01-01

164

Effect of modulator sorption on gradient shape in ion-exchange chromatography  

NASA Technical Reports Server (NTRS)

Mobile phase additives, or modulators, are used in gradient elution chromatography to facilitate separation and reduce separation time. The modulators are usually assumed to be linearly adsorbed or unadsorbed. Here, the consequences of nonlinear modulator adsorption are examined for ion-exchange gradient elution through a series of simulations. Even when the buffer salt is identical to the modulator salt, gradient deformation is observed; the extent of deformation increases as the volume of the feed is increased. When the modulator salt is different from the buffer salt, unusual effects are observed, and the chromatograms are quite different from those predicted by classical gradient elution theory. In particular, local increases in the buffer concentration are found between feed bands, and serve to improve the separation. These effects become more pronounced as the feed volume increases, and could therefore prove valuable in preparative applications.

Velayudhan, A.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

1995-01-01

165

Modeling of ion exchange expanded-bed chromatography for the purification of C-phycocyanin.  

PubMed

This work is focused on the experimental evaluation and mathematical modeling of ion exchange expanded-bed chromatography for the purification of C-phycocyanin from crude fermentative broth containing Spirulina platensis cells. Experiments were carried out in different expansion degree to evaluate the process performance. The experimental breakthrough curves were used to estimate the mass transfer and kinetics parameters of the proposed model, using the Particle Swarm Optimization algorithm (PSO). The proposed model satisfactorily fitted the experimental data. The results from the model application pointed out that the increase in the initial bed height does not influence the process efficiency, however enables the operation of expanded-bed column at high volumetric flow rates, improving the productivity. It was also shown that the use of mathematical modeling was a good and promising tool for the optimization of chromatographic processes. PMID:23411140

Moraes, Caroline Costa; Mazutti, Marcio A; Maugeri, Francisco; Kalil, Susana Juliano

2013-03-15

166

Impurity profiling of micronomicin sulfate injection by liquid chromatography-ion trap mass spectrometry.  

PubMed

The characterization of impurities present in micronomicin sulfate injection by liquid chromatography (LC) coupled with mass spectrometry (MS) is described. A reversed phase (RP)-LC method using a C?? column resistant to an alkaline (pH 11) aqueous mobile phase was developed and coupled to MS with an electrospray ionization (ESI) source in the positive ion mode which provides MS(n) capability. A total of thirty six impurities were detected in commercial samples: five impurities were identified by comparison of their fragmentation patterns with those of available related substances, eleven of them were identified in accordance with relevant literature, while the other twenty impurities were newly identified using the MS/MS spectra of the available related reference substances as interpretative templates combined with knowledge of the nature of functional group fragmentation behaviors. This work was applied to evaluate the quality of micronomicin sulfate injection from different manufacturers. PMID:23261805

Yuan, Yao-zuo; Zhao, Xun; Zhang, Mei; Fan, Xia-Lei; Hu, Chang-qin; Jin, Shao-hong; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

2013-03-01

167

Sensitive bioassay for the simultaneous determination of pseudoephedrine and cetirizine in human plasma by liquid-chromatography–ion trap spectrometry  

Microsoft Academic Search

A liquid chromatography–ion trap mass spectrometry coupled with electrospray ionization (HPLC–ESI–ion trap mass spectrometry) method for simultaneous determination of cetirizine and pseudoephedrine in human plasma is presented. Chromatographic separation was performed on a Hypurity C18 column (Thermo Hypersil-Keystone 2.1mm×150mm, 5?m, USA), The mobile phase was composed of 65% methanol and 35% water (contained 0.1% formic acid, 10mM ammonium formate), which

Zhi-Rong Tan; Dong-Sheng Ouyang; Gan Zhou; Lian-Sheng Wang; Zhi Li; Dan Wang; Hong-Hao Zhou

2006-01-01

168

Comparison of silver, gold and modified platinum electrodes for the electrochemical detection of iodide in urine samples following ion chromatography  

Microsoft Academic Search

The electrochemical (EC) detection of iodide at gold, silver and platinum electrodes under similar experimental conditions was evaluated. To achieve optimal amperometric detection, the electrode sensitivity, selectivity, and stability was compared. Isocratic separation of iodide was attained by ion chromatography (IC) using an anion-exchange column with nitrate as an eluent ion (25mM HNO3+50mM NaNO3). Although the Ag electrode showed the

Tommaso R. I. Cataldi; Alessandra Rubino; Maria Carmela Laviola; Rosanna Ciriello

2005-01-01

169

Formation of iron complexs from trifluoroacetic acid based liquid chromatography mobile phases as interference ions in liquid chromatography/electrospray ionization mass spectrometric analysis  

SciTech Connect

Two unexpected singly charged ions at m/z 1103 and 944 have been observed in mass spectra obtained from electrospray ionization-mass spectrometric analysis of liquid chromatography effluents with mobile phases containing trifluoroacetic acid. Accurate mass measurement and tandem mass spectrometry studies revealed that these two ions are not due to any contamination from solvents and chemicals used for mobile and stationary phases or from the laboratory atmospheric environment. Instead these ions are clusters of trifluoroacetic acid formed in association with acetonitrile, water and iron from the stainless steel union used to connect the column with the electrospray tip and to apply high voltage; the molecular formulae are Fe+((OH)(H2O)2)9(CF3COOH)5 and Fe+((OH)(H2O)2)6 (CF3COOH)5.

Shukla, Anil K.; Zhang, Rui; Orton, Daniel J.; Zhao, Rui; Clauss, Therese RW; Moore, Ronald J.; Smith, Richard D.

2011-05-30

170

Chemical Speciation Analysis of Sports Drinks by Acid-Base Titrimetry and Ion Chromatography: A Challenging Beverage Formulation Project  

ERIC Educational Resources Information Center

Students have standardized a sodium hydroxide solution and analyzed commercially available sports drinks by titrimetric analysis of the triprotic citric acid, dihydrogen phosphate, and dihydrogen citrate and by ion chromatography for chloride, total phosphate and citrate. These experiments are interesting examples of analyzing real-world food and…

Drossman, Howard

2007-01-01

171

ISOTOPE DILUTION ANALYSIS OF BROMATE IN DRINKING WATER MATRIXES BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION  

EPA Science Inventory

Bromate is a disinfection byproduct in drinking water which is formed during the ozonation of source water containing bromide. This paper described the analysis of bromate via ion chromatography-inductively coupled plasma mass spectrometry. The separation of bromate from interfer...

172

Retention mechanism of anions in micellar chromatography: Interpretation of retention data on the basis of an ion-exchange model  

Microsoft Academic Search

Micellar chromatography is an effective method not only for organic separations but also for inorganic separations because of its unique selectivity. Although a pseudo-phase model is widely utilized in the interpretation of the retention of neutral organic compounds, there is some ambiguity in applying this model to the quantitative description of the micellar chromatographic behaviour of inorganic ions. In this

Tetsuo Okada; Hidetomo Shimizu

1995-01-01

173

Comparison of Diafiltration and Size-Exclusion Chromatography to Recover Hemicelluloses From Process Water From Thermomechanical Pulping of Spruce  

NASA Astrophysics Data System (ADS)

Hemicelluloses constitute one of the most abundant renewable resources on earth. To increase their utilization, the isolation of hemicelluloses from industrial biomass side-streams would be beneficial. A method was investigated to isolate hemicelluloses from process water from a thermomechanical pulp mill. The method consists of three steps: removal of solids by microfiltration, preconcentration of the hemicelluloses by ultrafiltration, and purification by either size-exclusion chromatography (SEC) or diafiltration. The purpose of the final purification step is to separate hemicelluloses from small oligosaccharides, monosaccharides, and salts. The ratio between galactose, glucose, and mannose in oligo- and polysaccharides after preconcentration was 0.8?1?2.8, which is similar to that found in galactoglucomannan. Continuous diafiltration was performed using a composite fluoro polymer membrane with cutoff of 1000 Da. After diafiltration with four diavolumes the purity of the hemicelluloses was 77% (gram oligo- and polysaccharides/ gram total dissolved solids) and the recovery was 87%. Purification by SEC was performed with 5, 20, and 40% sample loadings, respectively and a flow rate of 12 or 25 mL/min (9 or 19 cm/h). The purity of hemicelluloses after SEC was approx 82%, and the recovery was above 99%. The optimal sample load and flow rate were 20% and 25 mL/min, respectively. The process water from thermomechanical pulping of spruce is inexpensive. Thus, the recovery of hemicelluloses is not of main importance. If the purity of 77%, obtained with diafiltration, is sufficient for the utilization of the hemicelluloses, diafiltration probably offers a less expensive alternative in this application.

Andersson, Alexandra; Persson, Tobias; Zacchi, Guido; Stålbrand, Henrik; Jönsson, Ann-Sofi

174

Quantification and characterization of dissolved organic nitrogen in wastewater effluents by electrodialysis treatment followed by size-exclusion chromatography with nitrogen detection.  

PubMed

Dissolved organic nitrogen (DON) can act as a precursor of nitrogenous disinfection byproducts during oxidative water treatment. Quantification and characterization of DON are still challenging for waters with high concentrations of dissolved inorganic nitrogen (DIN, including ammonia, nitrate and nitrite) relative to total dissolved nitrogen (TDN) due to the cumulative analytical errors of independently measured nitrogen species (i.e., DON = TDN - NO2(-) - NO3(-) - NH4(+)/NH3) and interference of DIN species to TDN quantification. In this study, a novel electrodialysis (ED)-based treatment for selective DIN removal was developed and optimized with respect to type of ion-exchange membrane, sample pH, and ED duration. The optimized ED method was then coupled with size-exclusion chromatography with organic carbon, UV, and nitrogen detection (SEC-OCD-ND) for advanced DON analysis in wastewater effluents. Among the tested ion-exchange membranes, the PC-AR anion- and CMT cation-exchange membranes showed the lowest DOC loss (1-7%) during ED treatment of a wastewater effluent at ambient pH (8.0). A good correlation was found between the decrease of the DIN/TDN ratio and conductivity. Therefore, conductivity has been adopted as a convenient way to determine the optimal duration of the ED treatment. In the pH range of 7.0-8.3, ED treatment of various wastewater effluents with the PC-AR/CMT membranes showed that the relative residual conductivity could be reduced to less than 0.50 (DIN removal >90%; DIN/TDN ratio ? 0.60) with lower DOC losses (6%) than the previous dialysis and nanofiltration methods (DOC loss >10%). In addition, the ED method is shorter (0.5 h) than the previous methods (>1-24 h). The relative residual conductivity was further reduced to ? 0.20 (DIN removal >95%; DIN/TDN ratio ? 0.35) by increasing the ED duration to 0.7 h (DOC loss = 8%) for analysis by SEC-OCD-ND, which provided new information on distribution and ratio of organic carbon and nitrogen in different molecular weight fractions of effluent organic matter. PMID:23916154

Chon, Kangmin; Lee, Yunho; Traber, Jacqueline; von Gunten, Urs

2013-09-15

175

Pilot-scale ion-exchange centrifugal partition chromatography: purification of sinalbin from white mustard seeds.  

PubMed

The purification of p-hydroxybenzylglucosinolate (sinalbin) on a multigram scale from a crude aqueous extract of white mustard seeds (Sinapis alba var. concerta) was successfully achieved by scaling up a strong ion-exchange centrifugal partition chromatography (SIXCPC) laboratory procedure. Thus, the one-step sinalbin purification was performed with 2.35 g of crude extract in approximately 170 min (830 mg/h) up to 70.3 g in approximately 160 min (26.3 g/h) by switching from a 200 mL laboratory scale column to a 5.7 L pilot-scale column. The required biphasic solvent system contained ethyl acetate, n-butanol, and water in 3:2:5 v/v/v proportions, Aliquat 336 (trioctylmethyl ammonium chloride) was added to the organic stationary phase (80 mM) and acted as ion-exchanger. Potassium iodide in the aqueous mobile phase (80 mM) was used as sinalbin displacer. The 28.5 mass scale factor arose from the increase in mobile phase flow-rate (from 2 to 50 mL/min), from the higher mass of injected white mustard seed extract (from 12 to 350 g), and from the calculated productivity (from 830 mg to 26.3 g). These results demonstrate that industry scale production of glucosinolates is easily performed by SIXCPC, thus providing pure reference standards for pharmacology studies. PMID:19479767

Toribio, Alix; Nuzillard, Jean-Marc; Pinel, Benoît; Boudesocque, Leslie; Lafosse, Michel; De La Poype, François; Renault, Jean-Hugues

2009-06-01

176

Design for gas chromatography-corona discharge-ion mobility spectrometry.  

PubMed

A corona discharge ionization-ion mobility spectrometry (CD-IMS) with a novel sample inlet system was designed and constructed as a detector for capillary gas chromatography. In this design, a hollow needle was used instead of a solid needle which is commonly used for corona discharge creation, helping us to have direct axial interfacing for GC-IMS. The capillary column was passed through the needle, resulting in a reaction of effluents with reactant ions on the upstream side of the corona discharge ionization source. Using this sample introduction design, higher ionization efficiency was achieved relative to the entrance direction through the side of the drift tube. In addition, the volume of the ionization region was reduced to minimize the resistance time of compounds in the ionization source, increasing chromatographic resolution of the instrument. The effects of various parameters such as drift gas flow, makeup gas flow, and column tip position inside the needle were investigated. The designed instrument was exhaustively validated in terms of sensitivity, resolution, and reproducibility by analyzing the standard solutions of methyl isobutyl ketone, heptanone, nonanone, and acetophenone as the test compounds. The results obtained by CD-IMS detector were compared with those of the flame ionization detector, which revealed the capability of the proposed GC-IMS for two-dimensional separation (based on the retention time and drift time information) and identification of an analyte in complex matrixes. PMID:23083064

Jafari, Mohammad T; Saraji, Mohammad; Sherafatmand, Hossein

2012-11-20

177

Colloidal aspects and packing behaviour of charged microparticulates in high efficiency ion chromatography.  

PubMed

The development of small particles in ion chromatography (IC) is a recent phenomenon. Very few studies are available on packing polymeric particles bearing ionizable functional groups. This study explores the colloidal and rheological properties that govern slurry packing to form high efficiency IC columns. The polymeric substrate used was non-porous 4.4 ?m sulfonated ethylvinylbenzene–divinylbenzene (1.4 mequiv. SO(3)H/g resin) with 55% crosslink. We developed simple tests optical microscopy and sedimentation tests for predicting the quality of packed columns. The negatively charged particles (zeta potential: ?52 mV in water) behave like colloids. The influence of counter-ion charge (Al(3+), Mg(2+), Na(+)) and ionic strength on column efficiency followed the Schulze–Hardy rule. Highly flocculating slurries give poorly packed columns with N ~ 900 whereas under non-agglomerating slurry conditions efficiencies up to N > 10,000 can be achieved. A non-agglomerating slurry also shows non-Newtonian behaviour, specifically shear thickening. Packing at lower flow rate (<1 mL/min) or higher temperature (>50 °C) reduces the shear thickening and produces higher efficiency columns. The packed sulfonated resin column is coated with 72 nm quaternary ammonium bearing latex (AS4A) and used in the separation of F(?), Cl(?), NO(2)(?), Br(?), and NO(3)(?) yielding a reduced plate height of 1.9 under optimum conditions. PMID:23218187

Wahab, M Farooq; Pohl, Christopher A; Lucy, Charles A

2012-12-28

178

Determination of five 4-hydroxycoumarin rodenticides in animal liver tissues by ion chromatography with fluorescence detection.  

PubMed

A novel analytical method is proposed for rapid simultaneous determination of five 4-hydroxycoumarin rodenticides in animal liver tissues by eluent generator reagent free ion chromatography (RFIC) with fluorescence detection. Rodenticides were initially extracted from homogenized animal liver tissues with ethyl acetate and the extracts subjected to a solid-phase extraction process using Oasis HLB cartridges. The IC separation was carried out on an IonPac AS11 analytical column (250 mm x 4.0 mm) using gradient KOH containing 10% acetonitrile as organic modifier at a constant flow rate of 1.0 mL/min. The analytes were detected by fluorescence at an excitation wavelength of 270 nm and an emission wavelength of 380 nm. The average recoveries of the objective compounds spiked in animal liver tissues were between 81% and 98%. The limits of quantification (LOQs) were 0.004-0.010 mg/kg for them. Within-day and day-to-day relative standard deviations (RSD) were less than 8.5% and 9.7%, respectively. It was confirmed that this method could be used in a toxicological analysis. PMID:17210156

Jin, Mi-Cong; Chen, Xiao-Hong; Zhu, Yan

2007-06-29

179

Indirect detection in reversed-phase liquid chromatography: Ion-pair retention models for cations on polystyrene polymers  

Microsoft Academic Search

Summary  The distribution equilibria of cationic compounds in reversed-phase chromatographic systems (ion-pair chromatography) have\\u000a been studied on the basis of their effect on a detectable mobile phase component. The solid phase was a polystyrene-divinylbenzene\\u000a copolymer and the detectable component, a quaternary ammonium ion, 1-methylpyridine. The solutes were mono- and divalent amines\\u000a and quaternary ammonium ions.\\u000a \\u000a The cations can be retained by

E. Arvidsson; J. Crommen; G. Schill; D. Westerlund

1987-01-01

180

LC-IMS-MS Feature Finder: Detecting Multidimensional Liquid Chromatography, Ion Mobility, and Mass Spectrometry Features in Complex Datasets  

SciTech Connect

We introduce a command line software application LC-IMS-MS Feature Finder that searches for molecular ion signatures in multidimensional liquid chromatography-ion mobility spectrometry-mass spectrometry (LC-IMS-MS) data by clustering deisotoped peaks with similar monoisotopic mass, charge state, LC elution time, and ion mobility drift time values. The software application includes an algorithm for detecting and quantifying co-eluting chemical species, including species that exist in multiple conformations that may have been separated in the IMS dimension.

Crowell, Kevin L.; Slysz, Gordon W.; Baker, Erin Shammel; Lamarche, Brian L.; Monroe, Matthew E.; Ibrahim, Yehia M.; Payne, Samuel H.; Anderson, Gordon A.; Smith, Richard D.

2013-09-13

181

Comprehensive analysis of pharmaceutical products using simultaneous mixed-mode (ion-exchange/reversed-phase) and hydrophilic interaction liquid chromatography.  

PubMed

Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual sample injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/sample was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks. PMID:24890905

Kazarian, Artaches A; Nesterenko, Pavel N; Soisungnoen, Phimpha; Burakham, Rodjana; Srijaranai, Supalax; Paull, Brett

2014-08-01

182

Process for separating acid-sugar mixtures using ion exclusion chromatography.  

National Technical Information Service (NTIS)

Work using a low-temperature concentrated sulfuric acid hydrolysis process to convert the cellulosic fraction of corn stover to monomeric sugars demonstrated the high conversion efficiencies possible with that process. The TVA work also confirmed the need...

G. E. Farina, R. D. Hester, S. W. Hartfield

1994-01-01

183

An automated high performance capillary liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometer for high-throughput proteomics.  

PubMed

We describe a fully automated high performance liquid chromatography 9.4 tesla Fourier transform ion resonance cyclotron (FTICR) mass spectrometer system designed for proteomics research. A synergistic suite of ion introduction and manipulation technologies were developed and integrated as a high-performance front-end to a commercial Bruker Daltonics FTICR instrument. The developments incorporated included a dual-ESI-emitter ion source; a dual-channel electrodynamic ion funnel; tandem quadrupoles for collisional cooling and focusing, ion selection, and ion accumulation, and served to significantly improve the sensitivity, dynamic range, and mass measurement accuracy of the mass spectrometer. In addition, a novel technique for accumulating ions in the ICR cell was developed that improved both resolution and mass measurement accuracy. A new calibration methodology is also described where calibrant ions are introduced and controlled via a separate channel of the dual-channel ion funnel, allowing calibrant species to be introduced to sample spectra on a real-time basis, if needed. We also report on overall instrument automation developments that facilitate high-throughput and unattended operation. These included an automated version of the previously reported very high resolution, high pressure reversed phase gradient capillary liquid chromatography (LC) system as the separations component. A commercial autosampler was integrated to facilitate 24 h/day operation. Unattended operation of the instrument revealed exceptional overall performance: Reproducibility (1-5% deviation in uncorrected elution times), repeatability (<20% deviation in detected abundances for more abundant peptides from the same aliquot analyzed a few weeks apart), and robustness (high-throughput operation for 5 months without significant downtime). When combined with modulated-ion-energy gated trapping, the dynamic calibration of FTICR mass spectra provided decreased mass measurement errors for peptide identifications in conjunction with high resolution capillary LC separations over a dynamic range of peptide peak intensities for each spectrum of 10(3), and >10(5) for peptide abundances in the overall separation. PMID:14766289

Belov, Mikhail E; Anderson, Gordon A; Wingerd, Mark A; Udseth, Harold R; Tang, Keqi; Prior, David C; Swanson, Kenneth R; Buschbach, Michael A; Strittmatter, Eric F; Moore, Ronald J; Smith, Richard D

2004-02-01

184

Chromatography Theory  

NSDL National Science Digital Library

This site contains standard definitions related to chromatography similar to treatments found in analytical chemistry textbooks. It introduces the beginning student to Liquid Chromatography concepts relevant to biochemistry and includes a good example of choosing a mobile phase pH for a protein separation based on ion exchange.

2011-05-26

185

Ion chromatography to detect salts in stone structures and to assess salt removal methods  

NASA Astrophysics Data System (ADS)

Stone - and in general all materials- from built heritage is very often damaged by salt crystallisation processes. Such processes usually derive into a loss of material compactness, as salts - given specific conditions and parameters- crystallize inside the material pores, exerting a pressure against the material pore walls higher than what they can resist - similar to the effect of liquid water when converts to solid water or ice-, thus breaking and disrupting the material by generating fissures and increasing the pore volume ratio, loosing its initial cohesion. When these deterioration processes take place inside a structure, salts - from different sources: material itself, restoration materials, from the ground, etc.- may come up to the stone surface - either temporarily or in permanently-, from beneath it, as efflorescences, depending mainly on the microclimatic conditions of the environment and the salts source. Efflorescences can be analysed and their nature identified (e.g. by means of X ray diffraction, in which the mineralogical composition of the salt is obtained), which can be, general, of aid not only for restoration but for preventive conservation measures. But what we do not know a priori when only characterising salt compounds- is the extent of the damage due to the presence of salts inside a structure (sub- and cryptoefflorescences). In this work we present a procedure in which the depth of the salt content can be measured, and its nature identified, based on the use of the ion chromatography technique. This technique allows identifying the existing ions in a specific sample, both anions and cations. The procedure consists of drilling (with a drilling core ranging from 5 to 8 mm in diameter, therefore causing the minimum damage to the material) in a same point at different depths from the surface and several depths from the bottom. The samples obtained are analysed and the ion content determined, qualitative and quantitatively. By means of a thorough previous inspection, we can select the most representative points by a drilling net - as minimum as possible- and make some profiles of the inner salt content of a structure. Moreover, this procedure is not only reliable for determining the nature and extent of salts damage, but to assess the efficacy of salts removal methods in cultural heritage. Here we present two case studies from relevant buildings of the Spanish cultural heritage in which this procedure was performed with successful and useful results, in both terms of understanding what types of salts were decaying the stones structures, and also whether the salts removal methods that were planned in the restoration project were efficient or not. It should be remarked that even ion chromatography is not a non destructive technique (can be considered as a minimally destructive one due to the few quantity it is needed for the analysis), the information it can provide is so useful that should not be ruled out from the beginning, depending of each specific case.

Alvarez de Buergo, M.; Lopez-Arce, P.; Fort, R.

2012-04-01

186

Discontinuous and continuous purification of single-chain antibody fragments using immobilized metal ion affinity chromatography.  

PubMed

This work describes the adsorption-desorption behavior of a histidine-tagged single-chain Fragment variable antibody (D1.3 scFv) on a commercial immobilized metal ion affinity chromatography (IMAC) column. A clarified cell culture supernatant originating from Bacillus megaterium was characterized using single column experiments in a pH-gradient elution mode. The cell culture supernatant containing the antibody fragment D1.3 scFv could be treated in the chromatographic separation process as a pseudo-binary mixture. Adsorption equilibrium constants of the antibody fragment fraction (ABF) and the non-specifically retained protein impurity fraction (IMP) were determined experimentally at constant pH by reinjecting pulses of pooled fractions collected in preliminary batch gradient elution runs. Based on the estimated adsorption equilibrium constants a possible multicolumn open-loop three-zone two-step pH-gradient simulated moving bed (SMB) process is suggested and designed, which possesses the potential to isolate continuously the antibody fragment fraction (ABF) containing the single-chain antibody fragment D1.3 scFv. PMID:22985797

Martínez Cristancho, Carlos Andrés; David, Florian; Franco-Lara, Ezequiel; Seidel-Morgenstern, Andreas

2013-01-20

187

Direct coupling of packed column supercritical fluid chromatography to continuous corona discharge ion mobility spectrometry.  

PubMed

In this study, packed column supercritical fluid chromatography (SFC) was directly coupled to a continuous corona discharge (CD) ion mobility spectrometer (IMS) with several modifications. The main advantage of the developed detector is its capability to introduce full column effluent up to 2000 mL min(-1) CO(2) gas directly into the IMS cell relative to 40 mL min(-1) CO(2) gas as a maximum tolerance, reported for the previous IMS detectors. This achievement was made possible because of using corona discharge instead of (63)Ni as an ionization source and locating the inlet and outlet of the CO(2) gas in the counter electrode of the CD in opposite direction. In addition, a heated interface was placed between back pressure regulator (BPR) and the IMS cell to heat the output of the BPR for introducing sample as the gas phase into the IMS cell. Furthermore, a make-up methanol flow was introduced between the column outlet and BPR to provide a more uniform flow through the BPR and also to prevent freezing and deposition of the analytes in the BPR. The performance of the SFC-CD-IMS was evaluated by analysis of testosterone, medroxyprogesterone, caffeine, and theophylline as test compounds and figures of merit for these compounds have been calculated. PMID:23261285

Rahmanian, A; Ghaziaskar, H S; Khayamian, T

2013-01-11

188

Dimethylamine and ammonia measurements with ion chromatography during the CLOUD4 campaign  

NASA Astrophysics Data System (ADS)

The CLOUD project investigates the influence of galactic cosmic rays on the nucleation of new particles in an environmental chamber at CERN. Ion chromatography was utilised together with a sampling device developed for CLOUD in order to measure ammonia (NH3) and dimethylamine (DMA) at low pptv levels. Sampling was performed by dissolving the gaseous NH3 and DMA, which were protonated and retained on trace cation concentrator columns as ammonium and dimethylaminium with an efficiency well above 95%. The sampling time varied between 70 and 210 min. A longer sampling time allowed a decrease of the detection limit for each species down to the sub-pptv level. NH3 mixing ratios reported were initially high du to an unintentional injection of NH3. They then recovered to background levels around 10 pptv, with no further injection of NH3. DMA was injected intentionally to reach atmospherically relevant levels away from sources (up to 60 pptv) in order to study its effect on nucleation with sulphuric acid and water at 278 K.

Praplan, A. P.; Bianchi, F.; Dommen, J.; Baltensperger, U.

2012-03-01

189

Anionic Forensic Signatures for Sample Matching of Potassium Cyanide Using High Performance Ion Chromatography and Chemometrics  

SciTech Connect

Potassium cyanide, a known poison, was used a model compound to determine the feasibility of using anionic impurities as a forensic signature for matching KCN samples back to their source. In this study, portions of eight KCN stocks originating from four countries were separately dissolved in water and analyzed by high performance ion chromatography (HPIC) using an anion exchange column and conductivity detection. Sixty KCN aqueous samples were produced from the eight stocks and analyzed for 11anionic impurities. Hierarchal cluster analysis and principal component analysis were used to demonstrate that KCN samples cluster according to source based on the concentrations of their anionic impurities. The F-ratio method and degree-of-class separation (DCS) were used for feature selection on a training set of KCN samples in order to optimize sample clustering. The optimal subset of anions needed for sample classification was determined to be sulfate, oxalate, phosphate, and an unknown anion named unk5. Using K-nearest neighbors (KNN) and the optimal subset of anions, KCN test samples from different KCN stocks were correctly determined to be manufactured in the United States. In addition, KCN samples from stocks manufactured in Belgium, Germany, and the Czech Republic were all correctly matched back to their original stocks because each stock had a unique anionic impurity profile. The application of the F-ratio method and DCS for feature selection improved the accuracy and confidence of sample classification by KNN.

Fraga, Carlos G.; Farmer, Orville T.; Carman, April J.

2011-01-30

190

Supercritical fluid extraction and gas chromatography/ion trap mass spectrometry of pentachloronitrobenzene pesticides in vegetables.  

PubMed

An analytical approach using supercritical fluid extraction (SFE) followed by gas chromatography/ion trap mass spectrometry (GC/ITMS) was developed for the analysis of the fungicide pentachloronitrobenzene and several analogues in vegetables. The method was tested in the analysis of carrots, potatoes, green beans, celery, and radishes fortified with pentachloronitrobenzene, tetrachloronitrobenzene, pentachloroanisole, pentachlorothioanisole, pentachlorobenzene, hexachlorobenzene, and pentachloroaniline. An incurred carrot sample analyzed by the method was shown to contain hexachlorobenzene at 7 +/- 3 ng/g, which agreed with the concentration (8 +/- 4 ng/g) determined using a traditional solvent-based method. The SFE method consisted of the following steps: (1) homogenizing a 50 g vegetable sample and weighing a 3 g subsample; (2) mixing 2 g sorbent (Hydromatrix) with the subsample to absorb moisture and packing a 10 mL extraction vessel; (3) extracting with 40 mL CO2 at 200 atm, 40 degrees C, and a flow rate of 3 mL/min; and (4) collecting the extract on a 1 g alumina basic trap at 25 degrees C and flushing with 8 mL isooctane. Collection of the extract on alumina efficiently removed chlorophyll and other matrix interferences. GC/ITMS in the electron-impact mode confirmed and quantitated the analytes at concentrations as low as 1 ng/g. PMID:7756861

Lehotay, S J; Ibrahim, M A

1995-01-01

191

Separation and simultaneous determination of four artificial sweeteners in food and beverages by ion chromatography.  

PubMed

In this paper, the separation and determination of four artificial sweeteners (aspartame, sodium cyclamate, acesulfame-K and sodium saccharin) by ion chromatography coupled with suppressed conductivity detector is reported. The four artificial sweeteners were separated using KOH eluent generator. Due to the use of eluent generator, very low conductance background conductivity can be obtained and sensitivity of sweeteners has been greatly improved. Under the experimental condition, several inorganic anions, such as F-, Cl-, NO3-, NO2-, Br-, SO4(2)-, PO4(3)- and some organic acid such as formate, acetate, benzoate, and citrate did not interfere with the determination. With this method, good linear relationship, sensitivity and reproducibility were obtained. Detection limits of aspartame, sodium cyclamate, acesulfame-K, sodium saccharin were 0.87, 0.032, 0.019, 0.045 mg/L, respectively. Rate of recovery were between 98.23 and 105.42%, 99.48 and 103.57%, 97.96 and 103.23%, 98.46 and 102.40%, respectively. The method has successfully applied to the determination of the four sweeteners in drinks and preserved fruits. PMID:16106861

Zhu, Yan; Guo, Yingying; Ye, Mingli; James, Frits S

2005-08-26

192

ANION ANALYSES BY ION CHROMATOGRAPHY FOR THE ALTERNATE REDUCTANT DEMONSTRATION FOR THE DEFENSE WASTE PROCESSING FACILITY  

SciTech Connect

The Process Science Analytical Laboratory (PSAL) at the Savannah River National Laboratory was requested by the Defense Waste Processing Facility (DWPF) to develop and demonstrate an Ion Chromatography (IC) method for the analysis of glycolate, in addition to eight other anions (fluoride, formate, chloride, nitrite, nitrate, sulfate, oxalate and phosphate) in Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) samples. The method will be used to analyze anions for samples generated from the Alternate Reductant Demonstrations to be performed for the DWPF at the Aiken County Technology Laboratory (ACTL). The method is specific to the characterization of anions in the simulant flowsheet work. Additional work will be needed for the analyses of anions in radiological samples by Analytical Development (AD) and DWPF. The documentation of the development and demonstration of the method fulfills the third requirement in the TTQAP, SRNL-RP-2010-00105, 'Task Technical and Quality Assurance Plan for Glycolic-Formic Acid Flowsheet Development, Definition and Demonstrations Tasks 1-3'.

Best, D.

2010-08-04

193

Laboratory robotics -- An automated tool for preparing ion chromatography calibration standards  

SciTech Connect

This paper describes the use of a laboratory robot as an automated tool for preparing multi-level calibration standards for On-Line Ion Chromatography (IC) Systems. The robot is designed for preparation of up to six levels of standards, with each level containing up to eleven ionic species in aqueous solution. The robot is required to add the standards` constituents as both a liquid and solid additions and to keep a record of exactly what goes into making up every standard. Utilizing a laboratory robot to prepare calibration standards provides significant benefits to the testing environment. These benefits include: accurate and precise calibration standards in individually capped containers with preparation traceability; automated and unattended multi-specie preparation for both anion and cation analytical channels; the ability to free up a test operator from a repetitive routine and re-apply those efforts to test operations; The robot uses a single channel IC to analyze each prepared standard for specie content and concentration. Those results are later used as a measure of quality control. System requirements and configurations, robotic operations, manpower requirements, analytical verification, accuracy and precision of prepared solutions, and robotic downtime are discussed in detail.

Chadwick, J.L.

1995-04-01

194

Analysis of succinylcholine in tissues and body fluids by ion-pair extraction and gas chromatography-mass spectrometry.  

PubMed

The neuromuscular blocking agent succinylcholine (SCh) has been identified and quantitated in biological material using gas chromatography-mass spectrometry. The bisquaternary ammonium compound SCh is extracted from tissue homogenates or body fluids into dichloromethane as an ion pair with hexanitrodiphenylamine (DPA). The evaporated ion pair residue is demethylated with sodium benzenethiolate to form the corresponding tertiary amine which is identified and quantitated by gas chromatography-mass spectrometry using a glass capillary column coated with SE 52. In the quantitative analysis deuterated SCh is used as internal standard. The instrument is focussed on m/z 58 for demethylated SCh and m/z 62 or 64 for the internal standard. Concentrations as low as 5 ng SCh iodide/g tissue or body fluid are easily detected. PMID:6578742

Nordgren, I K; Forney, R B; Carroll, F T; Holmstedt, B R; Jäderholm-Ek, I; Pettersson, B M

1983-01-01

195

Analysis of Camellia sinensis green and black teas via ultra high performance liquid chromatography assisted by liquid-liquid partition and two-dimensional liquid chromatography (size exclusion × reversed phase).  

PubMed

Green and black teas (Camellia sinensis) contain compounds ranging from simple phenolics to complex glycosides, many of which have well-recognized health benefits. Here, we describe two methodologies aiming to achieve a comprehensive analysis of hydro-alcoholic extracts of C. sinensis. In the first step, the extracts were partitioned in water, n-butanol, ethyl acetate and chloroform to separate the compounds according to their polarity, yielding less complex samples to be analyzed by ultra high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS). Additionally, a comprehensive two dimensional liquid chromatography (2D-LC) technique, employing size exclusion chromatography (SEC) × reversed phase (BEH-C18) was developed. The following compounds were identified on the basis of retention time, UV-spectra and MS fragmentation patterns: catechins, theaflavins and their gallate derivatives; kaempferol, quercetin and myricetin mono-, di-, tri- and tetraglycosides; esters of quinic acid and gallic or hydroxycinnamic acids; purine alkaloids, such as caffeine and theobromine and many lipids. Additionally, there were many novel compounds that were previously undescribed, such as saponin isomers and gallic acid esters of four glycosides of myricetin, quercetin and kaempferol. PMID:22204932

Scoparo, Camila T; de Souza, Lauro M; Dartora, Nessana; Sassaki, Guilherme L; Gorin, Philip A J; Iacomini, Marcello

2012-01-27

196

Determination of O-Isopropyl Methylphosphonic Acid in Living Microorganism-Agar Matrixes using ION Chromatography\\/Conductivity Detection  

Microsoft Academic Search

A direct anion exchange ion chromatography (IC)-based method for the detection of the chemical warfare (CW) agent degradation product, O-isopropyl methylphosphonic acid (IMPA) in agar medium has been developed. This is the first report of the development and validation of an IC-based method for the analysis of IMPA in a microorganism and agar matrix. In these experiments, IMPA served as

Alaa-Eldin F. Nassar; Samuel V. Lucas; Susan A. Thomas

1999-01-01

197

Determination of Tertiary-butylhydroquinone and Its Metabolites in Rat Serum by Liquid Chromatography–Ion Trap Mass Spectrometry  

Microsoft Academic Search

A new method applying sensitive and selective liquid chromatography coupled with mass spectrometry (LC\\/MS\\/MS) for analyzing\\u000a tertiary-butylhydroquinone (TBHQ) and its metabolites in rat serum was validated. Using an extracted ion chromatogram (EIC)\\u000a of m\\/z 149, free TBHQ was observed in rat serum after dosing TBHQ at 350 mg\\/kg to male and female Sprague–Dawley (SD) rats. Four\\u000a major metabolites of TBHQ

Wen Huang; Yinchun Gu; Hai Niu

2008-01-01

198

Determination of multiple pharmaceutical classes in surface and ground waters by liquid chromatography–ion trap–tandem mass spectrometry  

Microsoft Academic Search

This paper describes development, optimization and application of analytical method for determination and reliable confirmation of nineteen pharmaceuticals from different therapeutic classes (antibiotics—?-lactams, cephalosporines, sulfonamides, macrolides and tetracyclines; benzodiazepines; antiepileptics and analgoantipyretics) in surface and ground waters at ngl?1 levels. Water samples were prepared using solid-phase extraction and extracts were analyzed by liquid chromatography–ion trap–tandem mass spectrometry with electrospray ionization

Svetlana Gruji?; Tatjana Vasiljevi?; Mila Lauševi?

2009-01-01

199

Simultaneous Determination and Separation of Several Barbiturates and Analgesic Products by Ion-Pair High-Performance Liquid Chromatography  

Microsoft Academic Search

A sensitive, rapid, and accurate high-performance liquid chromatographic method for the simultaneous determination of several barbiturates and analgesic drugs is described. Reversed-phase ion-pair chromatography, using 1-decanesulfonic acid sodium salt as the counterion, was used. The method is rapid because no sample extraction is involved. Internal standards were used for the quantification. A ? Bondapak C18 column with a mobile phase

Fayez B. Ibrahim

1993-01-01

200

The determination of optical brighteners in laundry detergents by reverse phase and ion pair high performance liquid chromatography  

Microsoft Academic Search

Eleven optical brighteners have been qualitatively and quantitatively determined using C18, C8, or C2 reverse phase high performance liquid chromatography (HPLC) columns. Comparable results also were obtained using radially\\u000a compressed reverse phase HPLC cartridges. Mobile phases consist of acetonitrile and methanol in water with 0.05 M phosphate\\u000a buffer. Quaternary ammonium salts also are added to the mobile phase for ion

B. P. McPherson; N. Omelczenko

1980-01-01

201

Simultaneous determination of flunitrazepam and 7-aminoflunitrazepam in human serum by ion trap gas chromatography–tandem mass spectrometry  

Microsoft Academic Search

A method for the determination of flunitrazepam (FNZ) and 7-aminoflunitrazepam (7-AFNZ) in human serum was developed with ion trap gas chromatography (GC)–tandem mass spectrometry. The 7-AFNZ was derivatizated with 50?l trifluoroacetic anhydride (TFAA), 60°C-20min. EI mass spectra and tandem mass spectra of FNZ and 7-AFNZ-TFA were m\\/z 238, 239, 266, 286, 294, 312, 313(M+), m\\/z 350, 351, 360, 378, 379(M+),

Masaru Terada; Sousuke Masui; Takeshi Hayashi; Ritsuko Watanabe; Hiromasa Inoue; Morio Iino; Masato Nakatome; Ryoji Matoba; Tatsuo Shinozuka; Tatsuya Murai; Einosuke Tanaka; Katsuya Honda

2003-01-01

202

Simultaneous determination of cinnarizine and domepiridone maleate from tablet dosage form by reverse phase ion pair high performance liquid chromatography  

Microsoft Academic Search

A new simple, precise, rapid and selective reverse phase ion pair high performance liquid chromatography (HPLC-RP) method has been developed for the simultaneous determination of cinnarizine (CINN) and domepiridone maleate (DOME) from tablets using acetonitrile–methanol–water–0.1 N sulfuric acid (37:10:48:5 v\\/v\\/v\\/v) containing sodium lauryl sulfate (0.01 M), as a mobile phase and a Machery Nagel nitrile column (10 ?, 25 cm×4.0

A. P Argekar; S. J Shah

1999-01-01

203

DETERMINATION OF FLUOROQUINOLONE RESIDUES IN PENAEUS JAPONICUS BY MICROWAVE-ASSISTED EXTRACTION AND ION-PAIR HIGH PERFORMANCE LIQUID CHROMATOGRAPHY  

Microsoft Academic Search

A multi-residue method developed for the analysis of fluoroquinolone in Penaeus japonicus muscular tissue is presented. The method is based on microwave-assisted extraction (MAE) of Penaeus japonicus muscular tissue using acetonitrile as extractant and analysis of extracts by ion-pair high performance liquid chromatography (HPLC) and fluorescence detection. MAE operational parameters, the solvent type and volume, extraction temperature, and time were

Guiying Liu; Nianbin Wang; Li Wan; Bin Yang

2012-01-01

204

Metabolic profiling of flavonoids in Lotus japonicus using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry  

Microsoft Academic Search

Flavonoids detected from a model legume plant, Lotus japonicus accessions Miyakojima MG-20 and Gifu B-129, were profiled using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR\\/MS). Five flavonols and two anthocyanidins were detected as aglycones. LC-FTICR\\/MS facilitated simultaneous detection of 61 flavonoids including compounds that have not been reported previously. Chemical information of the peaks such as retention

Hideyuki Suzuki; Ryosuke Sasaki; Yoshiyuki Ogata; Yukiko Nakamura; Nozomu Sakurai; Mariko Kitajima; Hiromitsu Takayama; Shigehiko Kanaya; Koh Aoki; Daisuke Shibata; Kazuki Saito

2008-01-01

205

A Volatile Organic Analyzer for Space Station - Description and evaluation of a gas chromatography/ion mobility spectrometer  

NASA Technical Reports Server (NTRS)

An on-board Volatile Organic Analyzer (VOA), an essential component of the Environmental Health System (EHS) air-quality monitoring strategy, is described. The strategy is aimed at warning the crew and ground personnel if volatile compounds exceed safe exposure limits. The VOA uses a combination of gas chromatography (GC) and ion-mobility spectrometry (IMS) for environmental monitoring and analysis. It is concluded that the VOA dual-mode detection capability and the ion mobilities in the drift region are unique features that can assist in the resolution of coeluting GC peaks. The VOA is capable of accurately identifying and quantifying target compounds in a complex mixture.

Limero, Thomas; Brokenshire, John; Cumming, Colin; Overton, ED; Carney, Ken; Cross, Jay; Eiceman, Gary; James, John

1992-01-01

206

Separation of betalains from berries of Phytolacca americana by ion-pair high-speed counter-current chromatography  

Microsoft Academic Search

The first preparative fractionation of betalain pigments by means of ion-pair high-speed counter-current chromatography (IP-HSCCC) from berry extracts of Phytolacca americana (Phytolaccaceae) is presented. A novel HSCCC solvent system consisting of 1-butanol–acetonitrile–water (5:1:6, v\\/v\\/v) was applied using ion-pair forming trifluoroacetic acid at low concentration (0.7%, v\\/v). Affinity of polar betacyanins and betaxanthins to the organic stationary phase of the biphasic

Gerold Jerz; Tanja Skotzki; Kathrin Fiege; Peter Winterhalter; S?awomir Wybraniec

2008-01-01

207

Optimization of operating conditions for the determination of perchlorate in biological samples using preconcentration/preelution ion chromatography.  

PubMed

Perchlorate originates as a contaminant in the environment from the use of salts in the manufacture of solid rocket fuels and munitions. Monitoring potential perchlorate contamination in the environment is of interest, however, very few analytical methods have been developed for perchlorate determination in biological samples. Analysis of complex samples by ion chromatography is complicated by matrix components that can interfere with perchlorate determination. However, a recently developed preconcentration/preelution (PC/PE) ion chromatography method has demonstrated the capability to analyze certain complex samples such as high salinity water, milk, and hydroponic fertilizers. The ability of this method to reduce sample background and lower detection limits in ion chromatography for various biological samples was evaluated in this study. The PC/PE method was applicable to the analysis of kidneys, livers, zebrafish, quail eggs, lettuce, and urine. Optimal operating conditions were determined for each matrix. Ranges of optimal wash volumes were shorter when 15 mM NaOH prewash solutions were used compared with 10mM and good recovery was achieved for most matrices with an injection period > or =60s. Prewash solution concentration did not appear to significantly affect matrix background. The PC/PE method was capable of reducing sample background when compared to EPA Method 314.0, which resulted in detection limits, with the exception of zebrafish and urine, that were two-fold lower than those achieved with EPA Method 314.0. PMID:16310204

Cañas, Jaclyn E; Cheng, Qiuqiong; Tian, Kang; Anderson, Todd A

2006-01-20

208

Prepared polymethacrylate-based monoliths for the separation of cations by non-suppressed capillary ion chromatography.  

PubMed

This paper describes a novel analytical system for non-suppressed capillary ion chromatography. Methacrylate monolithic columns were prepared from silanized fused-silica capillaries of 320 µm i.d. by in situ polymerization of glycidyl methacrylate and ethylene dimethacrylate in the presence of 1,4-butanediol, 1-propanol and water as the porogen solvents. The introduction of cation-exchange sites was achieved by sulfonating the matrix with sodium sulfite to produce total cation-exchange capacities in the range of 45-105 ?equiv/mL for a 25 cm column. The conditions (concentrations of sodium sulfite solution, reacting time and modified flow rate) of sulfonation were optimized. The hydrodynamic and chromatographic performances were estimated. Coupled with a conductivity detector, a capillary ion chromatography system was set up with the prepared column. Finally, the resultant column was used for the separations of five common univalent cations (Li(+), Na(+), NH4(+), K(+) and Cs(+)) using methanesulfonic acid as the eluent and four divalent cations (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) by non-suppressed capillary ion chromatography; the chromatographic parameters were further researched. PMID:23677716

Li, Jing; Zhu, Yan

2014-01-01

209

Continuous processing of recombinant proteins: Integration of inclusion body solubilization and refolding using simulated moving bed size exclusion chromatography with buffer recycling.  

PubMed

An integrated process which combines continuous inclusion body dissolution with NaOH and continuous matrix-assisted refolding based on closed-loop simulated moving bed size exclusion chromatography was designed and experimentally evaluated at laboratory scale. Inclusion bodies from N(pro) fusion pep6His and N(pro) fusion MCP1 from high cell density fermentation were continuously dissolved with NaOH, filtered and mixed with concentrated refolding buffer prior to refolding by size exclusion chromatography (SEC). This process enabled an isocratic operation of the simulated moving bed (SMB) system with a closed-loop set-up with refolding buffer as the desorbent buffer and buffer recycling by concentrating the raffinate using tangential flow filtration. With this continuous refolding process, we increased the refolding and cleavage yield of both model proteins by 10% compared to batch dilution refolding. Furthermore, more than 99% of the refolding buffer of the raffinate could be recycled which reduced the buffer consumption significantly. Based on the actual refolding data, we compared throughput, productivity, and buffer consumption between two batch dilution refolding processes - one using urea for IB dissolution, the other one using NaOH for IB dissolution - and our continuous refolding process. The higher complexity of the continuous refolding process was rewarded with higher throughput and productivity as well as significantly lower buffer consumption compared to the batch dilution refolding processes. PMID:24169042

Wellhoefer, Martin; Sprinzl, Wolfgang; Hahn, Rainer; Jungbauer, Alois

2013-12-01

210

Kinetic size-exclusion chromatography with mass spectrometry detection: an approach for solution-based label-free kinetic analysis of protein-small molecule interactions.  

PubMed

Studying the kinetics of reversible protein-small molecule binding is a major challenge. The available approaches require that either the small molecule or the protein be modified by labeling or immobilization on a surface. Not only can such modifications be difficult to do but also they can drastically affect the kinetic parameters of the interaction. To solve this problem, we present kinetic size-exclusion chromatography with mass spectrometry detection (KSEC-MS), a solution-based label-free approach. KSEC-MS utilizes the ability of size-exclusion chromatography (SEC) to separate any small molecule from any protein-small molecule complex without immobilization and the ability of mass spectrometry (MS) to detect a small molecule without a label. The rate constants of complex formation and dissociation are deconvoluted from the temporal pattern of small molecule elution measured with MS at the exit from the SEC column. This work describes the concept of KSEC-MS and proves it in principle by measuring the rate constants of interaction between carbonic anhydrase and acetazolamide. PMID:25275785

Bao, Jiayin; Krylova, Svetlana M; Cherney, Leonid T; LeBlanc, J C Yves; Pribil, Patrick; Johnson, Philip E; Wilson, Derek J; Krylov, Sergey N

2014-10-21

211

OVERVIEW OF A NEW EPA METHOD: DETERMINATION OF PERCHLORATE IN DRINKING WATER, GROUNDWATER AND HIGH SALINITY WATER BY ION CHROMATOGRAPHY, SUPPRESSED CONDUCTIVITY WITH ELECTROSPRAY IONIZATION MASS SPECTROMETRIC DETECTION  

EPA Science Inventory

In this presentation the analytical instrumentation and procedures necessary to qualitatively and quantitatively determine low levels of perchlorate (ClO4-) in drinking waters using ion chromatography with electrolytic conductivity suppression, electrospray ionization mass spec...

212

Combining size-exclusion chromatography and fully automated chip-based nanoelectrospray quadrupole time-of-flight tandem mass spectrometry for structural analysis of chondroitin/dermatan sulfate in human decorin.  

PubMed

Chondroitin/dermatan sulfate (CS/DS) chain of decorin (DCN) from human skin fibroblasts (HSk) was released by reductive ?-elimination reaction and digested with chondroitin AC I lyase. Enzymatic hydrolysis mixture of CS/DS chains was separated by size-exclusion chromatography (SEC). Collected octasaccharide fraction was subjected to fully automated chip-based nanoelectrospray (nanoESI) quadrupole time-of-flight (QTOF) MS and tandem MS (MS/MS). MS of human skin fibroblasts DCN CS/DS displayed a high complexity due to the large variety of glycoforms, which under chip-nanoESI MS readily ionized to form multiply charged ions. Except for the regularly tetrasulfated octasaccharide, the investigated fraction contained four additional octasaccharides of atypical sulfation status. Two new oversulfated glycoforms and two undersulfated species were identified. Remarkably, the series of decasaccharides discovered in the same SEC pool was found to encompass a trisulfated and a novel hexasulfated [4,5-?-GlcAGalNAc(IdoAGalNAc)?] species. MS/MS by collision-induced dissociation (CID) on the [M-4H]? ion corresponding to the previously not reported [4,5-?-GlcAGalNAc(IdoAGalNAc)?](5S) corroborated for a novel motif in which three N-acetylgalactosamine (GalNAc) moieties are monosulfated, 4,5-?-GlcA and the first IdoA from the non-reducing end bear one sulfate group each, while the second N-acetylgalactosamine from the reducing end is unsulfated. PMID:21647927

Zamfir, Alina D; Flangea, Corina; Sisu, Eugen; Seidler, Daniela G; Peter-Katalini?, Jasna

2011-06-01

213

Adsorption of peptides and small proteins with control access polymer permeation to affinity binding sites. Part I: Polymer permeation-immobilized metal ion affinity chromatography separation adsorbents with polyethylene glycol and immobilized metal ions.  

PubMed

Despite the many efforts to develop efficient protein purification techniques, the isolation of peptides and small proteins on a larger than analytical scale remains a significant challenge. Recovery of small biomolecules from diluted complex biological mixtures, such as human serum, employing porous adsorbents is a difficult task mainly due to the presence of concentrated large biomolecules that can add undesired effects in the system such as blocking of adsorbent pores, impairing diffusion of small molecules, or competition for adsorption sites. Adsorption and size exclusion chromatography (AdSEC) controlled access media, using polyethylene glycol (PEG) as a semi-permeable barrier on a polysaccharide matrix, have been developed and explored in this work to overcome such effects and to preferentially adsorb small molecules while rejecting large ones. In the first part of this work, adsorption studies were performed with small peptides and proteins from synthetic mixtures using controlled access polymer permeation adsorption (CAPPA) media created by effectively grafting PEG on an immobilized metal affinity chromatography (IMAC) agarose resin, where chelating agents and immobilized metal ions were used as the primary affinity binding sites. Synthetic mixtures consisted of bovine serum albumin (BSA) with small proteins, peptides, amino acids (such as histidine or Val?-Angiotensin III), and small molecules-spiked human serum. The synthesized hybrid adsorbent consisted of agarose beads modified with iminodiacetic (IDA) groups, loaded with immobilized Cu(II) ions, and PEG. These CAPPA media with grafted PEG on the interior and exterior surfaces of the agarose matrix were effective in rejecting high molecular weight proteins. Different PEG grafting densities and PEG of different molecular weight were tested to determine their effect in rejecting and controlling adsorbent permeation properties. Low grafting density of high molecular weight PEG was found to be as effective as high grafting density of low molecular weight PEG in the rejecting properties of the semi-permeable synthesized media. PMID:22281505

González-Ortega, Omar; Porath, Jerker; Guzmán, Roberto

2012-03-01

214

Development of a new electron ionization/field ionization ion source for gas chromatography/time-of-flight mass spectrometry.  

PubMed

We have developed a combined EI/FI source for gas chromatography/orthogonal acceleration time-of-flight mass spectrometry (GC/oaTOFMS). In general, EI (electron ionization) and FI (field ionization) mass spectra are complementary: the EI mass spectrum contains information about fragment ions, while the FI mass spectrum contains information about molecular ions. Thus, the comparative study of EI and FI mass spectra is useful for GC/MS analyses. Unlike the conventional ion sources for FI and EI measurements, the newly developed source can be used for both measurements without breaking the ion source vacuum or changing the ion source. Therefore, the combined EI/FI source is more preferable than the conventional EI or FI ion source from the viewpoint of the reliability of measurements and facility of operation. Using the combined EI/FI source, the complementarity between EI and FI mass spectra is demonstrated experimentally with n-hexadecane (100 pg): characteristic fragment ions for the n-alkane such as m/z 43, 57, 71, and 85 are obtained in the EI mass spectrum, while only the parent peak of m/z 226 (M+) without any fragment ions is observed in the FI mass spectrum. Moreover, the field desorption (FD) measurement is also demonstrated with poly(ethylene glycol)s M600 (10 ng) and M1000 (15 ng). Signals of [M+H]+, [M+Na]+ and [M+K]+ are clearly detected in the FD mass spectra. PMID:19764073

Miyamoto, Kenji; Fujimaki, Susumu; Ueda, Yoshihisa

2009-10-30

215

A volatile organic analyzer for Space Station: Description and evaluation of a gas chromatography/ ion mobility  

NASA Technical Reports Server (NTRS)

A Volatile Organic Analyzer (VOA) is being developed as an essential component of the Space Station's Environmental Health System (EHS) air quality monitoring strategy to provide warning to the crew and ground personnel if volatile organic compounds exceed established exposure limits. The short duration of most Shuttle flights and the relative simplicity of the contaminant removal mechanism have lessened the concern about crew exposure to air contaminants on the Shuttle. However, the longer missions associated with the Space Station, the complex air revitalization system and the proposed number of experiments have led to a desire for real-time monitoring of the contaminants in the Space Station atmosphere. Achieving the performance requirements established for the VOA within the Space Station resource (e.g., power, weight) allocations led to a novel approach that joined a gas chromatograph (GC) to an ion mobility spectrometer (IMS). The authors of this paper will discuss the rational for selecting the GC/IMS technology as opposed to the more established gas chromatography/mass spectrometry (GC/MS) for the foundation of the VOA. The data presented from preliminary evaluations will demonstrate the versatile capability of the GC/IMS to analyze the major contaminants expected in the Space Station atmosphere. The favorable GC/IMS characteristics illustrated in this paper included excellent sensitivity, dual-mode operation for selective detection, and mobility drift times to distinguish co-eluting GC peaks. Preliminary studies have shown that the GC/IMS technology can meet surpass the performance requirements of the Space Station VOA.

Limero, Thomas F.; James, John T.

1994-01-01

216

Purification of a recombinant baculovirus of Autographa californica M nucleopolyhedrovirus by ion exchange membrane chromatography.  

PubMed

Significant progress in the application of viral vectors for gene delivery into mammalian cells and the use of viruses as biopesticides requires downstream processing that can satisfy application-specific demands on performance. In the present work the stability and ion exchange membrane chromatography of a recombinant of Autographa californica M nucleopolyhedrovirus is studied. To adjust the degree of purification the effect of ionic conductivity or pH on the viral infectivity was assessed (0.77-78.00mS/cm, pH 3-8). Infectivity decreased rapidly by several orders of magnitude at below 5mS/cm (i.e., 0.49MPa osmotic pressure change) or at below pH 5.5 (rationalized with particle aggregation). The virus was concentrated and purified via adsorption (0.2-1.1×10(16)pfu/m(3) chromatographic bed volume, 0.6-1.1×10(12)pfu/m(2) membrane area facing the incident fluid flow) and elution at pH 6.1 and 6.35mS/cm from three strong anion exchange membranes. Virus recovery and concentration in accord with the volume reduction were obtained using a polyether sulfone-based membrane with quaternary ammonium ligands. The level of host cell protein (down to below the detection limit) and suspended DNA (below 93pg DNA per 10(6)pfu) are reported for each membrane employed, for the purpose of comparability, under equal adsorption or elution conditions respectively. PMID:22521717

Grein, Tanja A; Michalsky, Ronald; Vega López, Maria; Czermak, Peter

2012-08-01

217

LC-IMS-MS Feature Finder: detecting multidimensional liquid chromatography, ion mobility and mass spectrometry features in complex datasets  

PubMed Central

Motivation: The addition of ion mobility spectrometry to liquid chromatography-mass spectrometry experiments requires new, or updated, software tools to facilitate data processing. Results: We introduce a command line software application LC-IMS-MS Feature Finder that searches for molecular ion signatures in multidimensional liquid chromatography-ion mobility spectrometry-mass spectrometry (LC-IMS-MS) data by clustering deisotoped peaks with similar monoisotopic mass, charge state, LC elution time and ion mobility drift time values. The software application includes an algorithm for detecting and quantifying co-eluting chemical species, including species that exist in multiple conformations that may have been separated in the IMS dimension. Availability: LC-IMS-MS Feature Finder is available as a command-line tool for download at http://omics.pnl.gov/software/LC-IMS-MS_Feature_Finder.php. The Microsoft.NET Framework 4.0 is required to run the software. All other dependencies are included with the software package. Usage of this software is limited to non-profit research to use (see README). Contact: rds@pnnl.gov Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24008421

Crowell, Kevin L.; Slysz, Gordon W.; Baker, Erin S.; LaMarche, Brian L.; Monroe, Matthew E.; Ibrahim, Yehia M.; Payne, Samuel H.; Anderson, Gordon A.; Smith, Richard D.

2013-01-01

218

Liquid chromatography with mass spectrometry method based two-step precursor ion scanning for the structural elucidation of flavonoids.  

PubMed

Plant flavonoids are very important secondary metabolites for insect and virus control of their host plant and are potent nutrients for humans. To be able to understand the bioavailability and functions of plant flavonoids, it is necessary to reveal their exact chemical structures. Liquid chromatography with tandem mass spectrometry is a powerful approach for structural elucidation of metabolites. In this report, a two-step precursor ion scanning based liquid chromatography with tandem mass spectrometry method was developed for the structural elucidation of plant flavonoids. The established method consists of the two-step precursor ions scanning for possible flavonoids extraction, MS(2) fragment spectra acquisition and comparison with an online database, liquid chromatography retention rules correction, and commercial standards verification. The developed method was used for the structure elucidation of flavonoids in flowers and leaves of tobacco (Nicotiana tabacum), and 17 flavonoids were identified in the tobacco variety Yunyan 97. Nine of the 17 identified flavonoids were considered to be found in tobacco flowers or/and leaves for the first time based on the available references. This method was proved to be very effective and can be used for the identification of flavonoids in other plants. PMID:25146381

Li, Yong; Pang, Tao; Shi, Junli; Lu, Xiuping; Deng, Jianhua; Lin, Qian

2014-11-01

219

Ion-exclusion chromatographic behavior of aliphatic carboxylic acids and benzenecarboxylic acids on a sulfonated styrene--divinylbenzene co-polymer resin column with sulfuric acid containing various alcohols as eluent.  

PubMed

The addition of C1-C7 alcohols (methanol, ethanol, propanol, butanol, heptanol, hexanol and heptanol) to dilute sulfuric acid as eluent in ion-exclusion chromatography using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as the stationary phase was carried out for the simultaneous separations of both (a) C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, 2-methylvaleric, isocaproic, caproic, 2,2-dimethyl-n-valeric, 2-methylhexanoic, 5-methylhexanoic and heptanoic acids) and (b) benzenecarboxylic acids (pyromellitic, hemimellitic, trimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic and salicylic acids and phenol). Heptanol was the most effective modifier in ion-exclusion chromatography for the improvement of peak shapes and a reduction in retention volumes for higher aliphatic carboxylic acids and benzenecarboxylic acids. Excellent simultaneous separation and relatively highly sensitive conductimetric detection for these C1-C7 aliphatic carboxylic acids were achieved on the TSKgel SCX column (150 x 6 mm I.D.) in 30 min using 0.5 mM sulfuric acid containing 0.025% heptanol as eluent. Excellent simultaneous separation and highly sensitive UV detection at 200 nm for these benzenecarboxylic acids were also achieved on the TSKgel SCX column in 30 min using 5 mM sulfuric acid containing 0.075% heptanol as eluent. PMID:12830881

Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

2003-05-16

220

Simultaneous determination of flunitrazepam and 7-aminoflunitrazepam in human serum by ion trap gas chromatography-tandem mass spectrometry.  

PubMed

A method for the determination of flunitrazepam (FNZ) and 7-aminoflunitrazepam (7-AFNZ) in human serum was developed with ion trap gas chromatography (GC)-tandem mass spectrometry. The 7-AFNZ was derivatizated with 50 microl trifluoroacetic anhydride (TFAA), 60 degrees C-20 min. EI mass spectra and tandem mass spectra of FNZ and 7-AFNZ-TFA were m/z 238, 239, 266, 286, 294, 312, 313(M(+)), m/z 350, 351, 360, 378, 379(M(+)), m/z 238, 239, 240 (precursor ion m/z 286, collision energy 1.5 V), and m/z 239, 254, 264, 336 (precursor ion m/z 351, collision energy 1.8 V), respectively. The detection limits of full scan EI mass spectrometry and tandem mass spectrometry for FNZ and 7-AFNZ in human serum were ca. 200 ng/ml, 60 ng/ml, 15 ng/ml and 1 ng/ml, respectively. PMID:12935562

Terada, Masaru; Masui, Sousuke; Hayashi, Takeshi; Watanabe, Ritsuko; Inoue, Hiromasa; Iino, Morio; Nakatome, Masato; Matoba, Ryoji; Shinozuka, Tatsuo; Murai, Tatsuya; Tanaka, Einosuke; Honda, Katsuya

2003-03-01

221

Principles and Methods Chromatography  

E-print Network

Edition AC 18-1022-29 Principles and Methods Affinity Chromatography #12;Antibody Purification-1142-75 Protein Purification Handbook 18-1132-29 Ion Exchange Chromatography Principles and Methods 18-1114-21 Affinity Chromatography Principles and Methods 18-1022-29 Hydrophobic Interaction Chromatography Principles

Lebendiker, Mario

222

Use of complexing reagents as additives to the eluent for optimization of separation selectivity in high-performance chelation ion chromatography  

Microsoft Academic Search

This paper details a study of the selectivity characteristics of high-performance chelation ion chromatography when separating a range of metal ions with a number of complexing eluents. It shows that exploitation of competitive metal complexation between ligands in the eluent and surface bonded chelating groups allows a wide range of control over the retention order and selectivity coefficients of groups

Phil Jones; Pavel N. Nesterenko

2008-01-01

223

Quality control considerations for size exclusion chromatography with online ICP-MS: a powerful tool for evaluating the size dependence of metal-organic matter complexation.  

PubMed

Size exclusion chromatography (SEC), which separates molecules based on molecular volume, can be coupled with online inductively coupled plasma mass spectrometry (ICP-MS) to explore size-dependent metal-natural organic matter (NOM) complexation. To make effective use of this analytical dual detector system, the operator should be mindful of quality control measures. Al, Cr, Fe, Se, and Sn all exhibited columnless attenuation, which indicated unintended interactions with system components. Based on signal-to-noise ratio and peak reproducibility between duplicate analyses of environmental samples, consistent peak time and height were observed for Mg, Cl, Mn, Cu, Br, and Pb. Al, V, Fe, Co, Ni, Zn, Se, Cd, Sn, and Sb were less consistent overall, but produced consistent measurements in select samples. Ultrafiltering and centrifuging produced similar peak distributions, but glass fiber filtration produced more high molecular weight (MW) peaks. Storage in glass also produced more high MW peaks than did plastic bottles. PMID:23416600

McKenzie, Erica R; Young, Thomas M

2013-01-01

224

Conductivity detection for molecular mass estimation of per-O-sulfonated glycosaminoglycans separated by high-performance size-exclusion chromatography.  

PubMed

Chemically per-O-sulfonated polysaccharides, including glycosaminoglycans (GAGs) and hyaluronan oligosaccharides were analyzed using high-performance size-exclusion chromatography (HPSEC) with suppressed conductivity detection. The results were compared to those obtained by gel filtration HPLC using UV detection or fluorescence detection after the post-column reaction with 2-cyanoacetamide in strong alkaline solution. Analysis was performed on a TSKgel G3000SWXL HPSEC column in 5 mM boric acid (pH 7.0 adjusted by 10 mM NaOH). The use of conductivity detection, in the absence of any derivatization and under isocratic conditions gave a limit of detection in the picogram range. Preliminary studies suggest that this approach may be particularly useful in examining sulfonated polysaccharides and oligosaccharides having no UV chromophore, such as those prepared from O-sulfonated fucans and galactans isolated from algae. PMID:12141565

Chaidedgumjorn, Amornrut; Suzuki, Atsushi; Toyoda, Hidenao; Toida, Toshihiko; Imanari, Toshio; Linhardt, Robert J

2002-06-14

225

Method development for the redox speciation analysis of iron by ion chromatography-inductively coupled plasma mass spectrometry and carryover assessment using isotopically labeled analyte analogues.  

PubMed

An ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) method was developed for the redox speciation analysis of iron (Fe) based on in-column complexation of Fe(2+) and Fe(3+) by dipicolinic acid (DPA). The effects of column type, mobile phase composition and molecular ion interference were studied in the method optimization. The carryover of the target species in the IC-ICP-MS method was uniquely and effectively evaluated using isotopically enriched analogues of the analytes ((54)Fe(2+) and (57)Fe(3+)). Standard solutions of the enriched standards were injected into the system following analysis of a sample, and the ratios of the isotopes of iron in the enriched standards were calculated based on the chromatographic peak areas. The concentrations of the analytes carried over from the sample to the enriched standards were determined using the quantitative relationship in isotope dilution mass spectrometry (IDMS). In contrast to the routine way of evaluating carryover effect by injecting a blank solution after sample analysis, the use of isotopically enriched standards identified significant analyte carryover in the present method. Extensive experiments were carried out to systematically identify the source of the carryover and to eliminate the problem; the separation column was found to be the exclusive source. More than 95% of the analyte carryover was eliminated by reducing the length of the column. The detection limit of the IC-ICP-MS method (MDL) for the iron species was 2ngg(-1). The method was used to determine Fe(2+) and Fe(3+) in synthetic aqueous standard solutions and a beverage sample. PMID:24819017

Wolle, Mesay Mulugeta; Fahrenholz, Timothy; Rahman, G M Mizanur; Pamuku, Matt; Kingston, H M 'Skip'; Browne, Damien

2014-06-20

226

Quantitative determination of noncovalently bound acridinium in protein conjugates by liquid chromatography/electrospray ion trap mass spectrometry.  

PubMed

A sensitive and robust liquid chromatography/electrospray ion trap mass spectrometry (LC/MS/MS) method has been developed for the quantitative determination of noncovalently bound acridinium free acid in protein-acridinium conjugates. The lower level of quantitation (LOQ) for acridinium free acid was determined to be 0.6 ng. The assay was validated with a linear concentration range of 0.6-60 ng. The method requires minimum sample handling and is specific, reproducible, and provides a new aspect for protein-acridinium conjugate characterization. PMID:11319787

Adamczyk, M; Gebler, J C; Shreder, K; Wu, J

2001-01-01

227

Separation of deuteriated isotopomers of dopamine by ion-pair reversed-phase high-performance liquid chromatography  

SciTech Connect

The ion-pair reversed-phase separation of dopamine and deuterium-substituted dopamine isotopomers is described. Chromatographic parameters and deuterium isotope effects governing the resolution are examined and compared to the factors regulating the resolution are examined and compared to the factors regulating the resolution of the chemically distinct entities dopamine, norepinephrine, and epinephrine. The potential utility of the (/sup 2/H/sub 7/)dopamine, isotopomer as an internal standard for the high-performance liquid chromatography analysis of dopamine is demonstrated by using aluminum oxide extraction prior to chromatographic separation.

Masters, C.F.; Markey, S.P.; Mefford, I.N.; Duncan, M.W.

1988-10-01

228

Using Second-derivative Filters to Assist in Width Estimations of Size Exclusion Chromatography Signal Peaks with Static Light-scattering Detections to Obtain More Accurate Molecular Weight.  

PubMed

Static light-scattering (LS) detection can determine the molecular weight (MW) of polymers eluted with size-exclusion chromatography (SEC) without using any standards when the differential refraction index (RI) of solutes are obtained. On the other hand, the noisy chromatographic signal peak acquired using a static LS detector often causes difficulty in peak-width recognition. This disadvantage limits the determination accuracy and precision of the MW values. This study developed one second-order derivative filtering procedure by convolving the original LS chromatogram against the second-derivative curve of one artificial Gaussian-shape chromatographic peak to suppress the noises and to correct the baseline of the chromatogram. More accurate estimations of the chromatographic peak widths of pullulan samples were achieved to improve the MW determination accuracy. For noisy original chromatography peaks of pullulan 5 k (SNR of approximately 10), the non-ideal determination accuracy of the MW values (9.3%) is improved to -1.3% with the assistance of the filtering procedures. PMID:25382042

Chen, Po-Ting; Chen, Hsiao-Ping; Hung, Chia-Hung; Wang, Shau-Chun

2014-01-01

229

Identification and quantification of active alkaloids in Catharanthus roseus by liquid chromatography-ion trap mass spectrometry.  

PubMed

Catharanthus roseus is an important dicotyledonous medicinal plant that produces anticancer compounds. The active alkaloids vinblastine, vindoline, ajmalicine, catharanthine, and vinleurosine were identified by direct-injection ion trap-mass spectrometry (IT-MS) for collecting MS(1-2) spectra. The determinations of five alkaloids were accomplished by liquid chromatography (LC) with UV and MS detections. The analytes provided good signals corresponding to the protonated molecular ions [M+H](+) and product ions. The precursor ions and product ions for quantification of vinblastine, vindoline, ajmalicine, catharanthine, and vinleurosine were m/z 825?807, 457?397, 353?144, 337?144 and 809?748 by LC-IT-MS, respectively. Two methods were used to evaluate a number of validation characteristics (repeatability, LOD, calibration range, and recovery). MS provided a high selectivity and sensitivity for determination of five alkaloids in positive mode. After optimisation of the methods, separation, identification and quantification of the five components in C. roseus were comprehensively accomplished by HPLC with UV and MS detection. PMID:23561180

Chen, Qinhua; Zhang, Wenpeng; Zhang, Yulin; Chen, Jing; Chen, Zilin

2013-08-15

230

An improved thin-layer chromatography/mass spectrometry coupling using a surface sampling probe electrospray ion trap system  

SciTech Connect

A combined surface sampling probe/electrospray emitter coupled with an ion trap mass spectrometer was used for the direct read out of unmodified reversed-phase C18 thin-layer chromatography (TLC) plates. The operation of the surface sampling electrospray ionization interface in positive and negative ionization modes was demonstrated through the direct analysis of TLC plates on which a commercial test mix comprised of four dye compounds viz., rhodamine B, fluorescein, naphthol blue black, and fast green FCF, and an extract of the caffeine-containing plant Ilex vomitoria, were spotted and developed. Acquisition of full-scan mass spectra and automated collection of MS/MS product ion spectra while scanning a development lane along the surface of a TLC plate demonstrated the advantages of using an ion trap in this combination. Details of the sampling system, benefits of analyzing a developed lane in both positive ion and negative ion modes, levels of detection while surface scanning, surface scan speed effects, and the utility of three-dimensional data display, are also discussed.

Ford, Michael J [ORNL; Van Berkel, Gary J [ORNL

2004-01-01

231

Ion-exchange chromatography: basic principles and application to the partial purification of soluble mammalian prolyl oligopeptidase.  

PubMed

Ion-exchange chromatography (IEC) allows for the separation of ionizable molecules on the basis of differences in charge properties. Its large sample-handling capacity, broad applicability (particularly to proteins and enzymes), moderate cost, powerful resolving ability, and ease of scale-up and automation have led to it becoming one of the most versatile and widely used of all liquid chromatography (LC) techniques. In this chapter, we review the basic principles of IEC, as well as the broader criteria for selecting IEC conditions. By way of further illustration, we outline protocols necessary to partially purify a serine peptidase from bovine whole brain cytosolic fraction, covering crude tissue extract preparation through to partial purification of the target enzyme using anion-exchange chromatography. Protocols for assaying total protein and enzyme activity in both pre- and post-IEC fractions are also described. The target serine peptidase, prolyl oligopeptidase (POP, EC3.4.21.26), is an 80-kDa enzyme with endopeptidase activity towards peptide substrates of ?30 amino acids. POP is a ubiquitous post-proline cleaving enzyme with particularly high expression levels in the mammalian brain, where it participates in the metabolism of neuroactive peptides and peptide-like hormones (e.g. thyroliberin, gonadotropin-releasing hormone). PMID:20978968

Cummins, Philip M; Dowling, Oonagh; O'Connor, Brendan F

2011-01-01

232

Simultaneous analysis of some transition metals at ultra-trace level by ion-exchange chromatography with on-line preconcentration  

Microsoft Academic Search

The quantitative analysis of six transition metals at concentrations below 1 ?g 1?1 was achieved using ion-exchange chromatography with on-line preconcentration. The metal ion are selectively retained on an iminodiacetate chelating stationary phase, then desorbed and transferred to a mixed-bed ion-exchange column for separation. Both the desorption from the concentrator column and the analysis on the separator column are made

S. Motellier; H. Pitsch

1996-01-01

233

Using liquid chromatography-ion trap mass spectrometry to determine pharmaceutical residues in Taiwanese rivers and wastewaters.  

PubMed

To establish their environmental concentrations and to support surface water protection programs, we have undertaken a preliminary study of the concentrations of selected acidic and neutral pharmaceutical residues (clofibric acid, ketoprofen, ibuprofen, diclofenac and carbamazepine) in Taiwanese river and wastewater samples. These pharmaceutical residues were extracted from the water samples through the Oasis HLB solid-phase extraction (SPE). The analytes were then identified and quantified using liquid chromatography-ion trap mass spectrometry with dual-polarity electrospray ionization in the product ion scan mode. The limits of quantification (LOQs) ranged between 0.5 and 20 ngl(-1) for 250 ml samples of water. We investigated the intra- and interbatch precision and accuracy at two levels of concentration. The selected analytes were detected at concentrations ranging from <0.5 to 960 ngl(-1) in wastewater treatment plant effluents and river water samples. PMID:18499225

Chen, Hsin-Chang; Wang, Pi-Lien; Ding, Wang-Hsien

2008-06-01

234

Counter electrode based on an ion-exchanger Donnan exclusion membrane for bioelectroanalysis.  

PubMed

Ion-exchanger based Donnan exclusion membranes (IEDEM) are studied here as separators for counter and pseudo-reference electrodes in bioelectroanalysis. Since the potential across the membrane remains indifferent for a wide range of current densities in contact with electrolyte solutions, IEDEM behave as ideally non-polarizable membranes. Consequently, such membranes may be suitable with counter or reference electrode, depending on the adopted cell configuration (three- or two-electrode system). Four configurations were characterized in order to establish the limitations of commercial anion-exchanging membranes, using chronopotentiometry as readout protocol. Three- and two-electrode configurations with and without membrane exhibited similar characteristics in terms of drift and reproducibility (observed drift and RSD were 0.0007 s(1/2) per scan number and 1.71%, respectively). Several currents amplitudes were applied to evaluate the upper current limits for the membranes, which was found at about 10 mA [42.8 mA cm(-2)]. This value is significantly above those typically used in chronopotentiometric experiments, which involve hundreds of ?A. Three different analytes were measured in human whole blood using an IEDEM as a counter electrode. A divalent cation (calcium), a polyion (protamine), and an anion (chloride) were successfully determined in blood and compared to reference methods. Finally, the obtained results suggest that such membranes may be used in bioelectrochemical sensing approaches to replace expensive but less appropriate electrode materials for the measurement in matrices that contain lipids and proteins. PMID:24858674

Afshar, Majid Ghahraman; Crespo, Gastón A; Bakker, Eric

2014-11-15

235

Energy transduction in the thermophilic anaerobic bacterium Clostridium fervidus is exclusively coupled to sodium ions.  

PubMed

The thermophilic, peptidolytic, anaerobic bacterium Clostridium fervidus is unable to generate a pH gradient in the range of 5.5-8.0, which limits growth of the organism to a narrow pH range (6.3-7.7). A significant membrane potential (delta psi approximately -60 mV) and chemical gradient of Na+ (-Z delta pNa approximately -60 mV) are formed in the presence of metabolizable substrates. Energy-dependent Na+ efflux is inhibited by the Na+/H+ ionophore monensin but is stimulated by uncouplers, suggesting that the Na+ gradient is formed by a primary pumping mechanism rather than by secondary Na+/H+ antiport. This primary sodium pump was found to be an ATPase that has been characterized in inside-out membrane vesicles and in proteoliposomes in which solubilized ATPase was reconstituted. The enzyme is stimulated by Na+, resistant to vanadate, and sensitive to nitrate, which is indicative of an F/V-type Na(+)-ATPase. In the proteoliposomes Na+ accumulation depends on the presence of ATP, is inhibited by the ATPase inhibitor nitrate, and is completely prevented by the ionophore monensin but is stimulated by protonophores and valinomycin. These and previous observations, which indicated that secondary amino acid transport uses solely Na+ as coupling ion, demonstrate that energy transduction at the membrane in C. fervidus is exclusively dependent on a Na+ cycle. PMID:8367451

Speelmans, G; Poolman, B; Abee, T; Konings, W N

1993-09-01

236

Combination of suppressed and non-suppressed ion chromatography with atmospheric pressure ionization mass spectrometry for the determination of anions.  

PubMed

Non-suppressed and suppressed ion chromatography in combination with atmospheric pressure ionization mass spectrometry are compared with special respect to sensitivity for the analysis of low-molecular-mass anions. Iodate, bromate, bromide, sulfate, thiosulfate and bromide could be separated by non-suppressed ion chromatography using a low-capacity anion-exchange column and ammonium citrate as mobile phase. Absolute detection limits between 0.4 and 0.7 ng could be achieved; employing a column requiring a flow-rate of 1 ml/min for optimum performance, splitting was necessary so that only 120 microliters/min entered the interface of the mass spectrometer resulting in detection limits between 0.03 and 0.06 mg/l. The same stationary phase (packed into a narrow-bore column which allowed operation without splitting) was suitable for the separation of oxyhalides in the suppressed mode with detection limits of 0.5 microgram/l (50 pg) with sodium carbonate as eluent. The method was applied to the analysis of drinking water for oxyhalides. The sample pretreatment for the removal of matrix anions (sulfate, chloride and hydrogencarbonate) is described. PMID:10457470

Buchberger, W; Ahrer, W

1999-07-30

237

Reversed-phase ion-pair liquid chromatography method for purification of duplex DNA with single base pair resolution  

PubMed Central

Obtaining quantities of highly pure duplex DNA is a bottleneck in the biophysical analysis of protein–DNA complexes. In traditional DNA purification methods, the individual cognate DNA strands are purified separately before annealing to form DNA duplexes. This approach works well for palindromic sequences, in which top and bottom strands are identical and duplex formation is typically complete. However, in cases where the DNA is non-palindromic, excess of single-stranded DNA must be removed through additional purification steps to prevent it from interfering in further experiments. Here we describe and apply a novel reversed-phase ion-pair liquid chromatography purification method for double-stranded DNA ranging in lengths from 17 to 51 bp. Both palindromic and non-palindromic DNA can be readily purified. This method has the unique ability to separate blunt double-stranded DNA from pre-attenuated (n-1, n-2, etc) synthesis products, and from DNA duplexes with single base pair overhangs. Additionally, palindromic DNA sequences with only minor differences in the central spacer sequence of the DNA can be separated, and the purified DNA is suitable for co-crystallization of protein–DNA complexes. Thus, double-stranded ion-pair liquid chromatography is a useful approach for duplex DNA purification for many applications. PMID:24013567

Wysoczynski, Christina L.; Roemer, Sarah C.; Dostal, Vishantie; Barkley, Robert M.; Churchill, Mair E. A.; Malarkey, Christopher S.

2013-01-01

238

The determination of inorganic sulphate in serum and synovial fluid by high performance ion chromatography.  

PubMed

A method for the determination of inorganic sulphate based on high performance ion chromatography is presented. The separation was performed on an anion-exchange column with a 1.8 mmol/l sodium carbonate/ 1.7 mmol/l sodium hydrogen carbonate-buffer, pH 10.35. Conductivity of the eluate was monitored after suppression of the background conductivity caused by the eluent-buffer. Serum and synovial fluid samples were prepared by ultrafiltration through membranes with a molecular mass cutoff of M(r) 10,000. The viscosity of the synovial fluids was reduced by treatment with hyaluronate lyase before ultrafiltration. The method showed a linear response for sulphate concentrations between 0.5 and 1000 mumol/l. The limit of detection was 1 mumol/l for aqueous standards. For serum the coefficient of variation within-run was 2.3%-2.4%, the coefficient of variation between days 2.9%-3.1%. For synovial fluids the coefficient of variation within-run was 3.1%-3.4%, the coefficient of variation between days 4.6%-5.7%. Standard recovery experiments performed by spiking pools of human sera containing low sulphate concentrations with sulphate concentrations between 5 mumol/l and 40 mumol/l showed recoveries between 98.9% and 100.6%. The corresponding experiments with pools of synovial fluids showed recoveries of 98.3% to 100.9%. As determined from 127 serum samples the reference range for sulphate was 262 mumol/l-420 mumol/l, with a mean value of 314 mumol/l. No dependence on age or sex was observed. The sulphate concentration in 36 synovial fluids from knees affected by inflammatory processes showed a mean value of 424 mumol/l and a standard deviation of 70 mumol/l. In 41 synovial fluids from knees affected by chronic degeneration joint disease, the sulphate concentrations were statistically significantly lower, with a mean of 374 mumol/l and a standard deviation of 58 mumol/l. The concentrations of sulphate in the synovial fluids were statistically significantly higher than those in the serum samples used for determination of the reference range. Following the oral application of a subtoxic single dose of acetaminophen (32.5 mg/kg body weight-62.5 mg/kg body weight) to 4 healthy volunteers, there was a significant decrease in the concentration of sulphate in serum with a minimum at 4-5 h after application of the drug. The cumulative concentration decrease of sulphate in serum and the kinetic constant of the sulphate depletion were not correlated with the applied acetaminophen dose normalized for body weight. PMID:9352230

Kock, R; Schneider, H; Delvoux, B; Greiling, H

1997-09-01

239

Determination of anionic minerals in black and kombucha tea using ion chromatography  

Microsoft Academic Search

A simple, rapid and accurate method for the determination of anionic minerals in tea brew has been developed. The quantitative determination of anions – fluoride, chloride, bromide, iodide, nitrate, phosphate and sulphate was accomplished by anion exchange chromatography with conductometric detection. A Metrosep Anion Dual 2 analytical column connected in series with a Metrosep RP guard column was used for

Sangita D. Kumar; G. Narayan; S. Hassarajani

2008-01-01

240

APPLICATION OF GC/ITD (GAS CHROMATOGRAPHY/ION TRAP DETECTOR) TO ENVIRONMENTAL ANALYSIS (JOURNAL VERSION)  

EPA Science Inventory

The choice of gas chromatography (GC) detectors has expanded rapidly. The necessity for mass spectrometric (MS) characterization of GC effluents stems from the complexity of the matrices associated with environmental samples. There are currently several MS types being used in con...

241

Kinetic analysis of the hydrodynamic transition accompanying protein folding using size exclusion chromatography. 1. Denaturant dependent baseline changes.  

PubMed

Size exclusion profiles of proteins with persistent conformations exhibit broad asymmetric peaks whose shape and elution times are dependent on denaturant concentration. The collective elution profiles were precisely simulated by an apparent binding model that treats the denaturant dependence in terms of an apparent matrix binding. The model requires three experimentally measurable parameters: the elution time for the unbound protein, an apparent association equilibrium constant for binding, and an apparent exchange time for binding. The denaturant dependence for each of these parameters is related to the accessible surface area of the protein. PMID:8427929

Shalongo, W; Heid, P; Stellwagen, E

1993-01-01

242

Liquid chromatography and ion trap mass spectrometry for simultaneous and multiclass analysis of antimicrobial residues in feed water.  

PubMed

This work firstly reported the development of liquid chromatography coupled to an ion trap mass spectrometer (LC-MS ion trap) for the simultaneous determination of nitrofurans (e.g. nitrofurazone (NFZ), nitrofurantoin (NFT), furazolidone (FZD) and furaltadone (FTD)), nitroimidazoles (e.g. metronidazole (MNZ), ronidazole (RNZ) and dimetridazole (DMZ)) and chloramphenicol (CAP) in feed water. Isotope-labeled internal standards for the corresponding target analytes were employed to prevent matrix effects that might lead to signal suppression/enhancement. High performance liquid chromatography (HPLC) analysis was performed on a Prodigy ODS-3 column, 2.0mm×150mm, 5?m with a guard cartridge at a flow rate of 0.2mL/min, column oven temperature of 40°C, and an injection volume of 10?L. Solid phase extraction (SPE) procedures, factors affecting HPLC separation (e.g. buffer pH and concentrations) and mass spectrometry (MS) parameters were optimized. After an off-line SPE by the OASIS HLB cartridges (with an enrichment factor of 400), the eight antimicrobial agents were separated in 18min using a gradient elution of acetonitrile in acidified water (pH 5.0). MS detection was by an ion trap MS coupled with electrospray ionization (ESI) in tandem mass spectrometry mode (MS/MS) using the nebulizer gas at 35psi, drying gas at 9L/min and drying temperature of 325°C. Method linearity was good (r(2)=0.979-0.999) with acceptable precision (% RSDs=3.4-26.6%) and accuracy (%recovery=88.4-110.1%). Very low limits of detection (LOD) and quantitation (LOQ) were achieved in ranges of 0.002-0.06?g/L and 0.005-0.25?g/L, respectively. The established method is successfully employed by the Department of Livestock Development of Thailand for the monitoring of the drug residues in feed waterbecause of its convenience, reliability and high sensitivity. PMID:24321758

Ardsoongnearn, Chusak; Boonbanlu, Ongart; Kittijaruwattana, Sunan; Suntornsuk, Leena

2014-01-15

243

Amperometric detection of amines using cobalt electrodes after separation by ion-moderated partition chromatography  

Microsoft Academic Search

A simple and low-cost amperometric sensor for amines has been developed using a cobalt wire electrode working in alkaline solution. The sensor may be used as a detector for high-performance liquid chromatography (HPLC) that avoids the need for derivatization or post-column reaction. Experimental conditions for flow injection analysis (FIA) and HPLC separation, including the applied potential, pH and concentrations of

A. Hidayat; D. B. Hibbert; P. W. Alexander

1997-01-01

244

MULTIPLE ELUENT AND PH EFFECTS ON ION CHROMATOGRAPHY OF PHOSPHATE AND ARSENATE  

EPA Science Inventory

The ion-exchange separation theory of Mayer and Tompkins is extended to the case of multiple eluent ions. The selectivity coefficients for carbonate and hydroxide, each relative to bicarbonate, were estimated from retention data for bromide and sulfate. These results were used to...

245

Metabolomic analysis via reversed-phase ion-pairing liquid chromatography coupled to a stand alone orbitrap mass spectrometer  

PubMed Central

We present a liquid chromatography-mass spectrometry (LC-MS) method that capitalizes on the mass-resolving power of the orbitrap to enable sensitive and specific measurement of known and unanticipated metabolites in parallel, with a focus on water soluble species involved in core metabolism. The reversed phase LC method, with a cycle time 25 min, involves a water-methanol gradient on a C18 column with tributylamine as the ion pairing agent. The MS portion involves full scans from 85 – 800 m/z at 1 Hz and 100,000 resolution in negative ion mode on a stand alone orbitrap (“Exactive”). The median limit of detection, across 80 metabolite standards, was 5 ng/mL with linear range typically ? 100-fold. For both standards and a cellular extract from Saccharomyces cerevisiae (Baker’s yeast), the median inter-run relative standard deviation in peak intensity was 8%. In yeast exact, we detected 137 known compounds, whose 13C-labeling patterns could also be tracked to probe metabolic flux. In yeast engineered to lack a gene of unknown function (YKL215C), we observed accumulation of an ion of m/z 128.0351, which we subsequently confirmed to be oxoproline, resulting in annotation of YKL215C as an oxoprolinase. These examples demonstrate the suitability of the present method for quantitative metabolomics, fluxomics, and discovery metabolite profiling. PMID:20349993

Lu, Wenyun; Clasquin, Michelle F.; Melamud, Eugene; Amador-Noguez, Daniel; Caudy, Amy A.; Rabinowitz, Joshua D.

2010-01-01

246

Determination of fluorine, chlorine and bromine in household products by means of oxygen bomb combustion and ion chromatography.  

PubMed

A method for routine determination of fluorine, chlorine and bromine in household products was developed and validated. In this work, halogen analyses were made based on oxygen bomb combustion followed by ion chromatography (IC). The chromatographic analysis was performed by an IonPac AS19 hydroxide-selective anion-exchange column, a reagent free ion chromatograph eluent generator and an anion self-regenerating suppressor in 10 min. The response was linear (r ? 0.9995) in the entire investigated domain. The limit of detection for the halogens was in the range of 2 to 9 × 10(-3) mg/L and the limit of quantification was lower than 8 mg/Kg with 20 µL of injection volume. The certified reference material of ERM-EC 681k was pretreated using an oxygen bomb combustion procedure to demonstrate the precision of the proposed method. The quantitative analysis results obtained by IC for the target elements were 797 ± 9 mg/Kg chlorine and 786 ± 25 mg/Kg bromine, which were in good agreement with the certified values of 800 ± 4 mg/Kg chlorine, 770 ± 5 mg/Kg bromine for ERM-EC 681k, respectively. This validated method was successfully applied for the analysis of fluorine, chlorine and bromine in household product samples, and the variation of halogen contained among the tested samples was remarkable. PMID:22752184

Zhang, Shuai; Zhao, Tianbo; Wang, Jia; Qu, Xiaoling; Chen, Wei; Han, Yin

2013-01-01

247

Immobilized palladium(II) ion affinity chromatography for recovery of recombinant proteins with peptide tags containing histidine and cysteine.  

PubMed

Fusion of peptide-based tags to recombinant proteins is currently one of the most used tools for protein production. Also, immobilized metal ion affinity chromatography (IMAC) has a huge application in protein purification, especially in research labs. The combination of expression systems of recombinant tagged proteins with this robust chromatographic system has become an efficient and rapid tool to produce milligram-range amounts of proteins. IMAC-Ni(II) columns have become the natural partners of 6xHis-tagged proteins. The Ni(II) ion is considered as the best compromise of selectivity and affinity for purification of a recombinant His-tagged protein. The palladium(II) ion is also able to bind to side chains of amino acids and form ternary complexes with iminodiacetic acid and free amino acids and other sulfur-containing molecules. In this work, we evaluated two different cysteine- and histidine-containing six amino acid tags linked to the N-terminal group of green fluorescent protein (GFP) and studied the adsorption and elution conditions using novel eluents. Both cysteine-containing tagged GFPs were able to bind to IMAC-Pd(II) matrices and eluted successfully using a low concentration of thiourea solution. The IMAC-Ni(II) system reaches less than 20% recovery of the cysteine-containing tagged GFP from a crude homogenate of recombinant Escherichia coli, meanwhile the IMAC-Pd(II) yields a recovery of 45% with a purification factor of 13. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25277090

Kikot, Pamela; Polat, Aise; Achilli, Estefania; Fernandez Lahore, Marcelo; Grasselli, Mariano

2014-11-01

248

Measurement of alkaline and earthy ions in fish otolith and sea water using a high performance ion chromatography  

Microsoft Academic Search

Fish growth and the relation between growth and environmental conditions offer a good opportunity for measuring alkaline and earthy ions in fish otoliths.The analytical method must involve high sensitivity when attempting to discriminate between fish growth and environmental conditions.The aim of this paper is to propose a chromatographic method, with low detection limits, as a new approach in determining some

M. Marini; A. Campanelli; F. Abballe

2006-01-01

249

Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection  

NASA Astrophysics Data System (ADS)

The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV-VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag+) by cation exchange chromatography with 0.5 M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04 mg kg- 1 detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm.

Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A.; Landero-Figueroa, Julio

2014-10-01

250

Detection of anionic energetic material residues in enhanced fingermarks on porous and non-porous surfaces using ion chromatography.  

PubMed

The ability to link criminal activity and identity using validated analytical approaches can be of great value to forensic scientists. Herein, the factors affecting the recovery and detection of inorganic and organic energetic material residues within chemically or physically enhanced fingermarks on paper and glass substrates are presented using micro-bore anion exchange chromatography with suppressed conductivity detection. Fingermarks on both surfaces were enhanced using aluminium powder or ninhydrin after spiking with model test mixtures or through contact with black-powder substitutes. A quantitative study of the effects of environmental/method interferences, the sweat matrix, the surface and the enhancement technique on the relative anion recovery of forensically relevant species is presented. It is shown that the analytical method could detect target analytes at the nanogram level even within excesses of enhancement reagents and their reaction products when using solid phase extraction and/or microfiltration. To our knowledge, this work demonstrates for the first time that ion chromatography can detect anions in energetic materials within fingermarks on two very different surfaces, after operational enhancement techniques commonly used by forensic scientists and police have been applied. PMID:23890630

Love, Catherine; Gilchrist, Elizabeth; Smith, Norman; Barron, Leon

2013-09-10

251

Plant lipidomics based on hydrophilic interaction chromatography coupled to ion trap time-of-flight mass spectrometry.  

PubMed

Plants synthesize a wide range of hydrophobic compounds, generally known as lipids. Here, we report an application of liquid chromatography ion trap time-of-flight mass spectrometry (LC-IT-TOF-MS) for plant lipidomics. Using hydrophilic interaction chromatography (HILIC) for class separation, typical membrane lipids including glycerolipids, steryl glucosides and glucosylceramides, and hydrophobic plant secondary metabolites such as saponins were analyzed simultaneously. By this method, we annotated approximately 100 molecules from Arabidopsis thaliana. To demonstrate the application of this method to biological study, we analyzed Arabidopsis mutant trigalactosyldiacylglycerol3 (tgd3), which has a complex metabolic phenotype including the accumulation of unusual forms of galactolipids. Lipid profiling by LC-MS revealed that tgd3 accumulated an unusual form of digalactosyldiacylglycerol, annotated as Gal(?1 ? 6)?GalDG. The compositional difference between normal and unusual forms of digalactosyldiacylglycerol was detected by this method. In addition, we analyzed well-known Arabidopsis mutants ats1-1, fad6-1, and fad7-2, which are also disrupted in lipid metabolic genes. Untargeted lipidome analysis coupled with multivariate analysis clearly discriminated the mutants and their distinctive metabolites. These results indicated that HILIC-MS is an efficient method for plant lipidomics. PMID:23463370

Okazaki, Yozo; Kamide, Yukiko; Hirai, Masami Yokota; Saito, Kazuki

2013-03-01

252

A solid phase extraction-ion chromatography with conductivity detection procedure for determining cationic surfactants in surface water samples.  

PubMed

A new analytical procedure for the simultaneous determination of individual cationic surfactants (alkyl benzyl dimethyl ammonium chlorides) in surface water samples has been developed. We describe this methodology for the first time: it involves the application of solid phase extraction (SPE-for sample preparation) coupled with ion chromatography-conductivity detection (IC-CD-for the final determination). Mean recoveries of analytes between 79% and 93%, and overall method quantification limits in the range from 0.0018 to 0.038 ?g/mL for surface water and CRM samples were achieved. The methodology was applied to the determination of individual alkyl benzyl quaternary ammonium compounds in environmental samples (reservoir water) and enables their presence in such types of waters to be confirmed. In addition, it is a simpler, less time-consuming, labour-intensive, avoiding use of toxic chloroform and significantly less expensive methodology than previously described approaches (liquid-liquid extraction coupled with liquid chromatography-mass spectrometry). PMID:24148395

Olkowska, Ewa; Polkowska, ?aneta; Namie?nik, Jacek

2013-11-15

253

Ligand-Exchange Chromatography of Aromatic Amines on Resin-Bound Cobalt Ion  

Microsoft Academic Search

The use of cobalt metal for the selective separation of aromatic amines is completed with a chemically bonded diamine and glyoxime functional groups onto Lycopodium clavatum. Oximes and amines are excellent complexing agents for transition metal ions. Cobalt(II) metal ions can easily be immobilized on bis-diami-noethyl-glyoximated sporopollenin (bDAEG-sporopollenin). The ligand-exchange behavior of modified Lycopodium clavatum with respect to aromatic amines

Erol Pehlivan; Ufuk S. Vural; Ahmet Ayar; Salih Yildiz

1996-01-01

254

Characterization of emtricitabine related substances by liquid chromatography coupled to an ion trap mass spectrometer.  

PubMed

Emtricitabine (FTC) is an antiretroviral compound that inhibits the HIV-1 reverse transcriptase. For the quantification of FTC related substances, a liquid chromatography (LC) method coupled with ultraviolet (UV) detection was developed earlier in our laboratory. Several unknown compounds were detected during the analysis of a commercial sample. However, most of these impurities were not characterized. In this study, impurity profiling in a selected FTC sample was done using LC-mass spectrometry (MS). Due to the presence of a non-volatile buffer, a desalting procedure was carried out before sending the impurity into the MS. Totally, nine peaks were studied and most of them could be characterized. PMID:20685446

Pendela, Murali; Mamade, Dunge Ashenafi; Hoogmartens, Jos; Van Schepdael, Ann; Adams, Erwin

2010-06-30

255

Hand-portable gas chromatography-ion mobility spectrometer for the determination of the freshness of fish  

NASA Technical Reports Server (NTRS)

A hand-held, portable gas chromatography-ion mobility spectrometer (GC-IMS) device was used to detect the presence of volatile amine compounds in the headspace of decomposing fish. The Food and Drug Administration (FDA) largely relies on olfactory discrimination with respect to fresh and spoiled, frozen and unfrozen fish. The fish are delivered at ship docks on pallets, and each pallet of fish can range from 30-40 thousand dollars in value. Fresh fish were placed in a teflon bag and the direct headspace was interrogated. In the first three days, only low molecular weight volatile amines were detected. On the fourth day, a number of spectral signatures were observed which indicated the presence of 1,5-diaminopentane, cadaverine. Analyses typically took from 0.5-1 minute.

Snyder, A. Peter; Harden, Charles S.; Davis, Dennis M.; Shoff, Donald B.; Maswadeh, Waleed M.

1995-01-01

256

Analysis of polyphenolic antioxidants from the fruits of three pouteria species by selected ion monitoring liquid chromatography-mass spectrometry.  

PubMed

Pouteria campechiana, Pouteria sapota, and Pouteria viridis are tropical plants in the Sapotaceae family that bear edible fruits. The fresh fruits of these three Pouteria species were each extracted, and activity-guided fractionations were performed to identify the antioxidant constituents. Seven polyphenolic antioxidants, gallic acid (1), (+)-gallocatechin (2), (+)-catechin (3), (-)-epicatechin (4), dihydromyricetin (5), (+)-catechin-3-O-gallate (6), and myricitrin (7), were isolated and identified. Extracts of the three Pouteria fruits were analyzed by a selected ion monitoring liquid chromatography-mass spectrometry method to quantify their polyphenolic antioxidants. The highest level of the seven measured polyphenols was found in P. sapota, the second highest in P. viridis, and the lowest in P. campechiana. The levels of the seven polyphenols corresponded with the results of the 1,1-diphenyl-2-picrylhydrazyl assay, by which P. sapota had the highest antioxidant activity, P. viridis the second highest, and P. campechiana the lowest. PMID:15366835

Ma, Jun; Yang, Hui; Basile, Margaret J; Kennelly, Edward J

2004-09-22

257

Simultaneous determination of amino acids and carbohydrates in culture media of Clostridium thermocellum by valve-switching ion chromatography.  

PubMed

An improved method for the simultaneous determination of 20 amino acids and 7 carbohydrates using one-valve switching after injection, ion chromatography, and integrated pulsed amperometric detection is proposed. The resolution of the amino acids and carbohydrates in the cation trap column was investigated. In addition, parameters including flow liquid type, flow rate, concentration, and valve-switch timing were optimized. The method is time-saving, effective, and accurate for the simultaneous separation of amino acids and carbohydrates, with a mean correlation coefficient of >0.99 and repeatability of 0.5-4.6% for eight replicates. The method was successfully applied in the analysis of amino acids and carbohydrates in aseptic media and in extracellular culture media of three phenotypes of Clostridium thermocellum. PMID:24070489

Fa, Yun; Yang, Haiyan; Ji, Chengshuai; Cui, He; Zhu, Xinshu; Du, Juan; Gao, Jun

2013-10-10

258

Purification of Hemoglobin from Red Blood Cells using Tangential Flow Filtration and Immobilized Metal Ion Affinity Chromatography  

PubMed Central

Two methods for purifying hemoglobin (Hb) from red blood cells (RBCs) are examined and compared. In the first method, red blood cell lysate is clarified with a 50 nm tangential flow filter and hemoglobin is purified using immobilized metal ion affinity chromatography (IMAC). In the second method, RBC lysate is processed with 50 nm, 500 kDa, and 50-100 kDa tangential flow filters, then hemoglobin is purified with IMAC. Our results show that the hemoglobins from both processes produce identical Hb products that are ultrapure and retain their biophysical properties (except for chicken hemoglobin, which shows erratic oxygen binding behavior after purification). Therefore, the most efficient method for Hb purification appears to be clarification with a 50 nm tangential flow filter, followed by purification with IMAC, and sample concentration/polishing on a 10-50 kDa tangential flow filter. PMID:21195679

Elmer, Jacob; Harris, David; Palmer, Andre F.

2011-01-01

259

[Analysis of kojic acid in Aspergillus oryzae ferment by ion-pair reversed-phase high performance liquid chromatography].  

PubMed

A new and an efficient method for analyzing kojic acid in aspergillus oryzae ferment by ion-pair reversed-phase high performance liquid chromatography was developed. The kojic acid was well separated on a C18 column using methanol-0.01 mol/L disodium hydrogen phosphate and 2 mmol tetrabutylammonium bromide (4:96) as the mobile phase, followed by an UV detection at 226 nm. The detection limit was 0.012 microgram/ml. The spiked recoveries in wort-yeast culture, wort-peptone culture and potato-yeast-sugar culture were 98.2%, 103.4% and 97.2%, respectively. The RSD values were 0.51%, 0.45% and 0.43% respectively. PMID:14535109

Zhao, Shan; Li, Yepeng; Zhao, Haiyan; Ji, Rong; Li, Yuwei

2003-07-01

260

Determination of amphetamine and methamphetamine in urine by solid phase extraction and ion-pair liquid chromatography–electrospray–tandem mass spectrometry  

Microsoft Academic Search

A method using a solid phase extraction (SPE) and ion-pair liquid chromatography–electrospray–tandem mass spectrometry (LC–ES–MS\\/MS) was developed for determination of amphetamine (Amp) and methamphetamine (mAmp) in urine samples. A reversed phase C18 column was utilized for LC separation and MS\\/MS was used for detection. Trifluoroacetic acid was added to the mobile phase as an ion-pairing reagent. MS2 was employed for

Ming-Ren Fuh; Ti-Yu Wu; Tzuen-Yeuan Lin

2006-01-01

261

Determination of fluorescent whitening agents in laundry detergents and surface waters by solid-phase extraction and ion-pair high-performance liquid chromatography  

Microsoft Academic Search

A simple method was developed to detect four stilbene-type disulfonate and one distyrylbiphenyl-type fluorescent whitening agents (FWAs) in household laundry detergents and surface waters by ion-pair high-performance liquid chromatography. The FWA concentrations in detergents were measured directly. The contents of FWAs in water samples were extracted by solid-phase extraction (C18-SPE) with ion-pairing reagent, and were then determined by an isocratic

Wei-Chuan Shu; Wang-Hsien Ding

2005-01-01

262

Analysis of nondistillables from coal liquids by size exclusion chromatography/Fourier transform infrared spectrometry (SEC/FT-IR)  

SciTech Connect

The separation of coal liquids by SEC is easily achieved with appropriate columns. Because coal-derived mixtures have several components of a similar size, the use of SEC alone is not adequate for the purpose of identification. Gas chromatography (GC) coupled with mass spectrometry (MS) has been used in conjunction with the SEC. The use of these three analytical techniques (SEC, GC, and MS) is a powerful analytical method for the analysis of the distillables of coal liquids, recycle solvents and anthracene oils. Analysis of SEC fractions of nondistillables by FT-IR spectrometry is very useful in characterizing the coal liquids produced under different reaction conditions. Conventional FT-IR techniques are rather unreliable as well as time consuming, because the mass of coal liquid in a SEC fraction is very small. A new technique, which is more reliable and requires less time than the conventional techniques, is developed for the analysis of small samples. The residues from SEC fractions are spotted onto a potassium bromide (KBr) pellet. The spotted samples are then analyzed using a narrow focused beam in the Microbeam accessory of a Nicolet 60 SXR FT-IR spectrometer. The paper discusses the analytical technique as well as the FT-IR spectra of SEC fractions.

Philip, C.V.; Anthony, R.G. (Texas A M Univ., College Station (USA))

1988-01-01

263

Liquid chromatography quadrupole linear ion trap mass spectrometry for multiclass screening and identification of lipophilic marine biotoxins in bivalve mollusks.  

PubMed

A liquid chromatography quadrupole linear ion trap mass spectrometry method with fast polarity switching and a scheduled multiple reaction monitoring algorithm mode was developed for multiclass screening and identification of lipophilic marine biotoxins in bivalve molluscs. A major advantage of the method is that it can detect members of all six groups of lipophilic marine biotoxins [okadaic acid (OA), yessotoxins (YTX), azaspiracids (AZA), pectenotoxins (PTX), cyclic imines (CI), and brevetoxins (PbTx)], thereby allowing quantification and high confidence identification from a single liquid chromatography tandem mass spectrometry (LC-MS/MS) injection. An enhanced product ion (EPI) library was constructed after triggered collection of data via information-dependent acquisition (IDA) of EPI spectra from standard samples. A separation method for identifying 17 target toxins in a single analysis within 12min was developed and tested. Different solid phase extraction sorbents, the matrix effect (for oyster, scallop, and mussel samples), and stability of the standards also were evaluated. Matrix-matched calibration was used for quantification of the toxins. The limits of detection were 0.12-13.6?g/kg, and the limits of quantification were 0.39-45.4?g/kg. The method was used to analyze 120 shellfish samples collected from farming areas along the coast of China, and 7% of the samples were found to be contaminated with toxins. The library search identified PbTx-3, YTX, OA, PTX2, AZA1, AZA2, and desmethylspirolide C (SPX1). Overall, the method exhibited excellent sensitivity and reproducibility, and it will have broad applications in the monitoring of lipophilic marine biotoxins. PMID:25086754

Wu, Haiyan; Guo, Mengmeng; Tan, Zhijun; Cheng, Haiyan; Li, Zhaoxin; Zhai, Yuxiu

2014-09-01

264

Temperature-dependent size exclusion chromatography for the in situ investigation of dynamic bonding/debonding reactions.  

PubMed

Polymers capable of dynamic bonding/debonding reactions are of great interest in modern day research. Potential applications can be found in the fields of self-healing materials or printable networks. Since temperature is often used as a stimulus for triggering reversible bonding reactions, an analysis operating at elevated temperatures is very useful for the in situ investigation of the reaction mechanism, as unwanted side effects can be minimized when performing the analyses at the same temperature at which the reactions occur. A temperature-dependent size exclusion chromatographic system (TD SEC) has been optimized for investigating the kinetics of retro Diels-Alder-based depolymerization of Diels-Alder polymers. The changing molecular weight distribution of the analyzed polymers during depolymerization gives valuable quantitative information on the kinetics of the reactions. Adequate data interpretation methods were developed for the correct evaluation of the chromatograms. The results are confirmed by high-temperature dynamic light scattering, thermogravimetric analysis, and time-resolved nuclear magnetic resonance spectroscopy at high temperatures. In addition, the SEC system and column material stability under application conditions were assessed using thermoanalysis methods, infrared spectroscopy, nitrogen physisorption, and scanning electron microscopy. The findings demonstrate that the system is stable and, thus, we can reliably characterize such dynamically bonding/debonding systems with TD SEC. PMID:23877179

Brandt, Josef; Guimard, Nathalie K; Barner-Kowollik, Christopher; Schmidt, Friedrich G; Lederer, Albena

2013-11-01

265

Influence of ionic strength and organic modifier concentrations on characterization of aquatic fulvic and humic acids by high-performance size-exclusion chromatography.  

PubMed

Aquatic fulvic acid (FA) and humic acid (HA) were characterized by an aqueous high-performance size-exclusion chromatography (HPSEC) using a hydrophilic polymeric stationary phase and an aqueous eluent at neutral pH and low-ionic strength (5 mM Na2HPO4; final ionic strength, 13 mM). Employed HPSEC showed low sensitivity of FA to variations in ionic strength (13 and 100 mM) and contents of organic modifier (0.1 or 40% methanol) in aqueous eluent. Under these analytical conditions, peak maxima of relative UV signals versus molecular mass (Mr) defined as M'p and peak maxima of relative mass concentrations versus Mr defined as Mp of FA were shown to be located at 548-690 and 500, respectively. Organic modifier concentrations of 40% methanol in aqueous eluent enabled not only analysis of FA, but also analysis of some aquatic HA by HPSEC. Analysis showed M'p and Mp values of aquatic HAs around 1000 and 600, respectively. Measured molecular mass data of FA were found to be consistent with the recently published data describing low molecular masses of FA. Results recommend the use of the described HPSEC as a simple, rapid, reproducible, low-cost method giving consistent molecular sizes/masses of FA and some aquatic HAs. PMID:14584694

Hoque, Enamul; Wolf, Manfred; Teichmann, Günter; Peller, Ernst; Schimmack, Wolfgang; Buckau, Gunnar

2003-10-31

266

Absolute molecular weight distribution of low-molecular-weight heparins by size-exclusion chromatography with multiangle laser light scattering detection.  

PubMed

The absolute molecular weight (M(r)) distribution of seven low-molecular-weight (LMW) heparin products was determined by size-exclusion chromatography (SEC) coupled with multiangle laser light scattering (MALLS) detection. The SEC/MALLS technique does not rely on relative M(r) standards for column calibration and yields absolute M(r) estimates directly from the angular dependence of scattered light intensity as a function of concentration, as formulated by light scattering theory. The SEC/MALLS method we describe is rapid, precise, and accurate. In 1 h it yields results from triplicate injections that agree well with the manufacturers' own independent analyses and that exhibit coefficients of variation of approximately 1%. By eliminating the requirement for finite quantities of highly purified, well-characterized M(r) standards derived from heparin, the present procedure represents a clear improvement over relative methods of M(r) determination. Thus, it is concluded that the SEC/MALLS method is ideally suited to routine quality control of commercial LMW-heparin products. PMID:9056218

Knobloch, J E; Shaklee, P N

1997-02-15

267

Assessment of the influence of amylose-LPC complexation on the extent of wheat starch digestibility by size-exclusion chromatography.  

PubMed

Amylose forms inclusion complexes with lysophosphatidylcholine (LPC), that decrease the susceptibility of amylose to amylase degradation. This study on the influence of complexation on starch susceptibility to amylase explains the nature of this protective effect. Wheat starch suspensions (9% w/w) containing 0.5-5% LPC were subjected to hydrolysis by porcine pancreatic ?-amylase at 37 °C for several digestion times. The digesta were analysed by size-exclusion chromatography (SEC). The molar mass distribution was closely dependent on the digestion time and amount of LPC. This study precisely demonstrates the alteration of the digestion profile of starch on a molecular level, influenced by amylose-LPC complexation; however the effect depends on the digestion time. During 15 and 30 min digestion, inclusion complexes not only protect amylopectin in the initial hydrolysis stage, but also demonstrate lower susceptibility of the molecular amylose complexes to amylase hydrolysis. Digestion for 240 min resulted in a lower oligosaccharide peak concentration, in the presence of a high LPC concentration, which is related to less degradation of complexed amylose fraction. PMID:23993621

Ahmadi-Abhari, S; Woortman, A J J; Hamer, R J; Loos, K

2013-12-15

268

Evaluations of the TiO2/simulated solar UV degradations of XAD fractions of natural organic matter from a bog lake using size-exclusion chromatography.  

PubMed

This work reports on the changes in compositions of humic acids (HAs) and fulvic acids (FAs) during photocatalytic degradation. The HAs and FAs were obtained from the XAD-resin fractionation of natural-organic matter (NOM) from a bog lake (Lake Hohloh, Black Forest, Germany). Degussa P-25 titanium dioxide (TiO2) in a suspension and a solar UV simulator (batch reactor) were used in the experiments. The photocatalytic degradation of the HAs and FAs were monitored using size-exclusion chromatography (SEC) equipped with dissolved organic carbon (DOC) and ultraviolet (UV254) detection (SEC-DOC and SEC-UV254) and UV-Vis spectrophotometry. The evolutions of the photocatalytic degradations of the HA and FA fractions were selective. The photocatalytic degradation started with the degradations of high molecular weight compounds with relatively high UV254 absorbances in the HA and FA fractions to yield low molecular weight compounds showing less specific UV254 absorbances. Observance of the same tendency for the original NOM from Lake Hohloh indicates that these XAD-fractions still having complex compound mixtures. However, the larger molecular weight fractions of the FAs showed higher preferential adsorptions onto TiO2, which caused their faster degradation rates. Furthermore, FAs showed a greater reduction of the total THM formation potential (TTHMFP) and the organic halogen compounds adsorbable on activated carbon formation potential (AOXFP), in comparison with the HAs. PMID:23863374

Valencia, Sergio; Marín, Juan M; Restrepo, Gloria; Frimmel, Fritz H

2013-09-15

269

The use of high-performance size exclusion chromatography (HPSEC) as a molecular weight screening technique for polygalacturonic acid for use in pharmaceutical applications.  

PubMed

Polygalacturonic acid is a linear carbohydrate polymer of monomeric galacturonic acid. It is commercially available as apple and citrus pectins comprised of a mixture of partially methoxylated and/or amidated polygalacturonic acids with molecular weights ranging from 25,000 to > 100,000 Da. Pectin can be chemically or enzymatically hydrolyzed to yield polygalacturonic acid fractions of diverse average molecular weight ranges and polydispersities for a variety of uses. Pectin and polygalacturonic acid are used extensively as gelling agents and stabilizers by the food industry, and have applications as therapeutic, and diagnostic pharmaceutical agents such as the magnetic resonance imaging agent LumenHance. A simple high-performance size exclusion chromatography (HPSEC) method, employing commonly available non-specialized HPLC instrumentation, is described for use as a rapid molecular weight screening technique to determine the average molecular weight range and polydispersity of polygalacturonic acid intended for use in pharmaceutical formulations. A TosoHaas G3000PWXL HPLC column, 50 mM phosphate buffer (pH approximately 6.9) mobile phase, and refractive index detection were used. A molecular weight calibration curve was linear for polysaccharide standards of 180-100,000 Da with a coefficient of correlation of 0.999. The method was employed to screen commercially available polygalacturonic acid raw materials for average molecular weight data (Mn, Mw, and Mp) and polydispersity (Mw/Mn). PMID:10746959

White, G W; Katona, T; Zodda, J P

1999-09-01

270

Rapid analysis of trace levels of antibiotic polyether ionophores in surface water by solid-phase extraction and liquid chromatography with ion trap tandem mass spectrometric detection  

Microsoft Academic Search

The occurrence of antibiotics in surface and ground water is an emerging area of interest due to the potential impacts of these compounds on the environment. This paper details a rapid, sensitive and reliable analytical method for the determination of monensin A and B, salinomycin and narasin A in surface water using solid-phase extraction (SPE) and liquid chromatography–ion trap tandem

J. M. Cha; S. Yang; K. H. Carlson

2005-01-01

271

Determination of inorganic cations and ammonium in environmental waters by ion chromatography with a high-capacity cation-exchange column  

Microsoft Academic Search

While alkali and alkaline earth cations are commonly determined by using spectrometric techniques such as atomic absorption spectrometry or inductively coupled plasma, ammonium cation in the same sample must be measured separately by a wet chemical technique such as colorimetry, titrimetry, or ammonia-selective electrode. In a single 25-min run ion chromatography can determine all of the important inorganic cations including

D. H. Thomas; M. Rey; P. E. Jackson

2002-01-01

272

Analysis of underivatized amino acids in geological samples using ion-pairing liquid chromatography and electrospray tandem mass spectrometry.  

PubMed

The capability of detecting biomarkers, such as amino acids, in chemically complex field samples is essential to establishing the knowledge required to search for chemical signatures of life in future planetary explorations. However, due to the complexities of in situ investigations, it is important to establish a new analytical scheme that utilizes a minimal amount of sample preparation. This paper reports the feasibility of a novel and sensitive technique, which has been established to quantitate amino acids in terrestrial crust samples directly without derivatization using volatile ion-pairing liquid chromatography and tandem mass spectrometry equipped with an electrospray ionization source. Adequate separation of 20 underivatized amino acids was achieved on a C(18) capillary column within 26 min with nonafluoropentanoic acid (NFPA) as ion-pairing reagent. Each amino acid was identified from its retention time as well as from its characteristic parent-to-daughter ion transition. Using tandem mass spectrometry as a detection technique allows co-elution of some amino acids, as it is more specific than traditional spectrophotometric methods. In the present study, terrestrial samples collected from 3 different locations were analyzed for their water-extractable free amino acid contents, following the removal of metal and organic interferences via ion exchange procedures. This is the first time that amino acids in geological samples were directly determined quantitatively without complicated derivatization steps. Depending on the amino acid, the detection limits varied from 0.02 to 5.7 pmol with the use of a 1 microl sample injection loop. PMID:18393689

Liu, De-Ling; Beegle, Luther W; Kanik, Isik

2008-04-01

273

Characterization of diacylglycerol isomers in edible oils using gas chromatography-ion trap electron ionization mass spectrometry.  

PubMed

Verifying the authenticity of edible oils is of international concern. A new quality control standard for olive oil has been proposed that relates the ratio of 1,2-diacylglycerol (DAG) to 1,3-DAG to sensory aspects of olive oil. DAGs and their isomers are difficult to quantitate and characterize by Flame Ionization Gas Chromatography (GC-FID) due to the lack of suitable standards. Mass detectors offer the advantage of providing structural detail to the eluding DAG(s), thus removing ambiguity to the identification of both resolved and unresolved DAGs in GC chromatograms. In this study, a GC Electron Ionization Mass Spectrometry (GC-EI-MS) method was developed to determine the fatty acid composition and molecular structure of trimethylsilyl (TMS) derivatized DAGs present in edible oils. Twenty-two species of DAG isomers were identified in refined coconut oil and unrefined olive oil utilizing signature fragment ions, [M-15](+), [M-89](+), [M-RCO2](+), [RCO2+58](+) and [M-RCO2CH2](+). The [M-RCO2CH2](+) ion is considered the key diagnostic ion to distinguish between DAG positional isomers. MS/MS spectra of [M-RCO2](+) and [M-15](+) ions obtained from commercial standards containing both 1,2- and 1,3-DAG isomers were used as a model system to confirm the identification of DAG isomers in natural products. Furthermore, a number of reaction mechanisms are proposed to explain the formation of the most abundant mass fragments of DAGs and their isomers. PMID:23880469

Zhu, Hanjiang; Clegg, Michael S; Shoemaker, Charles F; Wang, Selina C

2013-08-23

274

[Simultaneous determination of 25 persistent organic pollutants in rice by gas chromatography-mass spectrometry with selected ion monitoring mode].  

PubMed

A multi-residue analytical method for the simultaneous determination of persistent organic pollutants (POPs) in rice samples was developed. POPs were extracted from rice with ethyl acetate/n-hexane (80:20, v/v) by sonication, and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode. A fused silica capillary column DB-35MS (30 m x 0.25 mm i.d. x 0.25 microm) was employed. Operating conditions were as follows: injector port temperature, 300 degrees C; column temperature, programming; carrier gas, helium; flow rate, 1.0 mL/min; sample size, 1 microL with splitless injection. The mass spectrometric detector (MSD) was operated in electron impact ionization mode with an ionizing energy of 70 eV. Analysis was performed with selected ion monitoring (SIM) using one target and one or two qualifier ion. POPs were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.05, 0.1, and 0.5 mg/L spiked levels of each POPs, and the recoveries obtained ranged from 81.99% to 100.60% with relative standard deviations between 2.37% and 18.48%. The detection limits of the method ranged from 0.1 to 5 ng/g for the different POPs except endrin, trans-chlordane and cis-chlordane. The results show that the method developed is sensitive and reliable. PMID:16124561

Hou, Shengjun; Chen, Dandan; Li, Xiang; Li, Gang; Yang, Qiang; Min, Shungeng; Zhong, Weike; Chu, Xiaogang; Wang, Daning

2005-05-01

275

Analysis of indandione anticoagulant rodenticides in animal liver by eluent generator reagent free ion chromatography coupled with electrospray mass spectrometry.  

PubMed

A novel analytical method has been developed for simultaneous determination of four indandione anticoagulant rodenticides (diphacinone, chlorophacinone, pindone and valone) in animal liver tissues by eluent generator reagent free ion chromatography coupled with electrospray ionization mass spectrometry (RFIC-ESI-MS). After the rodenticides were extracted from homogenized animal liver tissues with methanol-acetonitrile (10/90, v/v), the extracts were subjected to a solid-phase extraction (SPE) process using Oasis HLB cartridges. The IC separation was carried out on an IonPac AS11 analytical column (250 mm x 4.0 mm) using 10% methanol in a gradient of KOH solution at a constant flow rate of 1.0 mL/min. The objective compounds were ionized by negative ion pneumatically assisted electrospray and detected in the selected ion monitoring (SIM) mode. Warfarin was applied as an internal standard (IS) for the compensation of the losses in the course of sample processing and the sensitivity drift of the detector, linear calibration functions were calculated for all analytes. The relative average recoveries of the objective compounds spiked in animal liver tissues were between 83.4 and 104.9%. The limits of quantification (LOQs) were 0.2-1.0 ng/g for them. Within-day and day-to-day relative standard deviations (RSDs) were less than 10.4 and 13.3%, respectively. It was confirmed that this method could be used in a toxicological analysis. The coupling of IC to MS provided a new analytical tool to the analysts faced with the requirement of separating and analyzing indandione rodenticides in animal livers. PMID:18804211

Jin, Mi-cong; Chen, Xiao-hong; Ye, Ming-li; Zhu, Yan

2008-12-01

276

The direct determination of urinary oxalate by non-suppressed ion chromatography.  

PubMed

In this paper we describe a simple ion chromatographic method for determination of oxalate in urine. Acidified urine was diluted 1:2 with 0.03 mol/l benzidine hydrochloride in 0.3 mol/l boric acid to precipitate sulphate. The supernatant was passed through a C18-cartridge and 100 microliters of eluant were injected into an ion chromatographic system. Oxalate was measured by nonsuppressed conductivity detection. The detection limit for urinary oxalate was 0.05 mmol/l. The recovery for spiked urine samples was 101.5% with a CV of 4.5%. The within- and between-assay coefficients of variation were less than 4.5% and 2.5%, respectively. We found the results obtained by this method to be statistically equivalent to an enzymatic assay and a different ion-chromatographic method. PMID:9166975

Pfeiffer, K; Berg, W; Bongartz, D; Hesse, A

1997-04-01

277

Characterizing string-of-pearls colloidal silica by multidetector hydrodynamic chromatography and comparison to multidetector size-exclusion chromatography, off-line multiangle static light scattering, and transmission electron microscopy.  

PubMed

The string-of-pearls-type morphology is ubiquitous, manifesting itself variously in proteins, vesicles, bacteria, synthetic polymers, and biopolymers. Characterizing the size and shape of analytes with such morphology, however, presents a challenge, due chiefly to the ease with which the "strings" can be broken during chromatographic analysis or to the paucity of information obtained from the benchmark microscopy and off-line light scattering methods. Here, we address this challenge with multidetector hydrodynamic chromatography (HDC), which has the ability to determine, simultaneously, the size, shape, and compactness and their distributions of string-of-pearls samples. We present the quadruple-detector HDC analysis of colloidal string-of-pearls silica, employing static multiangle and quasielastic light scattering, differential viscometry, and differential refractometry as detection methods. The multidetector approach shows a sample that is broadly polydisperse in both molar mass and size, with strings ranging from two to five particles, but which also contains a high concentration of single, unattached "pearls". Synergistic combination of the various size parameters obtained from the multiplicity of detectors employed shows that the strings with higher degrees of polymerization have a shape similar to the theory-predicted shape of a Gaussian random coil chain of nonoverlapping beads, while the strings with lower degrees of polymerization have a prolate ellipsoidal shape. The HDC technique is contrasted experimentally with multidetector size-exclusion chromatography, where, even under extremely gentle conditions, the strings still degraded during analysis. Such degradation is shown to be absent in HDC, as evidenced by the fact that the molar mass and radius of gyration obtained by HDC with multiangle static light scattering detection (HDC/MALS) compare quite favorably to those determined by off-line MALS analysis under otherwise identical conditions. The multidetector HDC results were also comparable to those obtained by transmission electron microscopy (TEM). Unlike off-line MALS or TEM, however, multidetector HDC is able to provide complete particle analysis based on the molar mass, size, shape, and compactness and their distributions for the entire sample population in less than 20 min. PMID:21428298

Brewer, Amandaa K; Striegel, André M

2011-04-15

278

Ligand-exchange chromatography of aromatic amines on resin-bound cobalt ion  

SciTech Connect

The use of cobalt metal for the selective separation of aromatic amines is completed with a chemically bonded diamine and glyoxime functional groups onto Lycopodium clavatum. Oximes and amines are excellent complexing agents for transition metal ions. Cobalt(II) metal ions can easily be immobilized on bis-diaminoethyl-glyoximated sporopollenin (bDAEG-sporopollenin). The ligand-exchange behavior of modified Lycopodium clavatum with respect to aromatic amines was investigated. This will permit the evaluation of bDAEG-sporopollenin ligand exchangers for their utilization as sorbents in the recovery, pollution control, and elimination of amines from wastewater.

Pehlivan, E.; Vural, U.S.; Ayar, A.; Yildiz, S. [Selcuk Univ., Konya (Turkey)

1996-06-01

279

Forensic Applications of Gas Chromatography-Differential Mobility Spectrometry, Gas Chromatography/Mass Spectrometry, and Ion Mobility Spectrometry with Chemometric Analysis.  

E-print Network

?? Rapid, practical, and low-cost analytical methods are always desirable in forensic analysis. Using proper sample preparation techniques with the application of gas chromatography/mass spectrometry… (more)

Lu, Yao

2010-01-01

280

Chromatography and the hundred year mystery of inorganic ions at aqueous interfaces: adsorption of inorganic ions at the Porous Graphitic Carbon Aqueous Interface follows the Hofmeister series.  

PubMed

Many physical phenomena are affected by the structure of water interfaces, yet it remains an active and controversial subject. A great deal of recent theoretical endeavour and computer simulations question the validity of the Onsager Samaras theory of the ion-free interface between an electrolyte solution and an hydrophobic surface. Experimental results play a crucial role in assessing the legitimacy of the theories. Experimental data are scarce, while simulation results suggest an increasing surface affinity of ions with increasing chaotropic character, in dramatic contradiction to the classical view. Chromatography is a powerful separative technique, but we originally used it as a tool to detect the adsorption of chloride electrolytes and sodium electrolytes, strongly expected to shun any dielectric boundary, onto an hydrophobic surface, and to rank ions according to their adsorbophilicities. Frontal analysis gave unequivocal experimental evidence to this unexpected phenomenon and it was used to quantify it. The infinite dilution equilibrium constants for adsorption of kosmotropes and chaotropes onto the interface were obtained and contrasted to the Jones-Dole B viscosity coefficients, that is a common quantifier of the Hofmeister effect. It is clear that (i) the more chaotropic the ion is, the more it contributes to the global adsorbophilicity of the electrolyte; (ii) the influence of the variable anion is more than twofold that of the variable cation, thereby confirming a robust observation in many other physical systems. Standard free energy of adsorption for each electrolyte was calculated and its reliability was commented upon. The central issue in this paper is the effective and ascertained adsorption of electrolytes onto an hydrophobic surface and the fact that the adsorbophilicity of an electrolyte may be inferred from its position in the Hofmeister series. PMID:24075459

Cecchi, Teresa; Marcotulli, Federica

2013-11-01

281

Enrichment method of sulfated glycopeptides by a sulfate emerging and ion exchange chromatography.  

PubMed

Sulfated glycoproteins are of growing importance for biomarker discovery, as well as for investigating molecular recognition processes. Mass spectrometry (MS) has become a powerful technique for the characterization of glycans and glycoproteins. However, characterization and detection of sulfated glycopeptides by MS is difficult because of the low abundance and low ionization efficiency of these molecules. To overcome this problem, we developed a novel enrichment procedure for sulfated glycopeptides. The procedure consists of anion exchange chromatography and a sulfate emerging (SE) method which controls the net charge of peptides by utilizing limited proteolyzes and modification with acetohydrazide. Using this procedure, we are able to enrich and characterize the sulfated glycopeptides of bovine luteinizing hormone (bLH). Furthermore, we demonstrate the enrichment and detection of sulfated glycopeptides from a complex mixture comprising human serum spiked with bLH at a concentration of 0.1%. PMID:19572564

Toyoda, Masaaki; Narimatsu, Hisashi; Kameyama, Akihiko

2009-08-01

282

Integrated cation–anion\\/volatile fluid inclusion analysis by gas and ion chromatography; methodology and examples  

Microsoft Academic Search

Combined gas and ion chromatographic analysis of well characterized, small (?1 g) fluid inclusion-bearing samples is a powerful, but simple, means for obtaining integrated fluid concentrations of major and trace, volatile and ionic fluid constituents without using microthermometrically determined salinity for normalization. The methodology, which is described and assessed in detail, involves crushing a carefully cleaned sample at ?105°C in

D. M. DeR Channer; C. J Bray; E. T. C Spooner

1999-01-01

283

Determination of iodide in ground water and soil by ion chromatography  

Microsoft Academic Search

Comprehensive elemental analysis of samples from the Bear Creek Valley near the Oak Ridge Y-12 Plant, and its floodplain have been performed in order to allow an unclassified assessment of possible elemental contamination within this area. A rapid ion Chromatographic method, with isocratic separation and micromembrane suppression is discussed within this paper for the analysis of iodide in soils, and

H. L Tucker; R. W Flack

1998-01-01

284

A comprehensive method for lipid profiling by liquid chromatography-ion cyclotron resonance mass spectrometry[S  

PubMed Central

This work aims to combine chromatographic retention, high mass resolution and accuracy, MS/MS spectra, and a package for automated identification and quantitation of lipid species in one platform for lipidomic analysis. The instrumental setup elaborated comprises reversed-phase HPLC coupled to a Fourier transform ion cyclotron resonance mass spectrometer (LTQ-FT), and Lipid Data Analyzer (LDA) software. Data analysis for lipid species quantification in this platform is based on retention time, mass resolution of 200,000, and mass accuracy below 2 ppm. In addition, automatically generated MS/MS spectra provide structural information at molecular level. This LC/MS technology allows analyzing complex biological samples in a quantitative manner as shown here paradigmatically for murine lipid droplets having a huge surplus of triacylglycerol species. Chromatographic preseparation of the bulk lipid class alleviates the problem of ion suppression of lipid species from other classes. Extension of 1D to 2D chromatography is possible, yet time consuming. The platform affords unambiguous detection of lipid species as low as 0.1‰ within major lipid classes. Taken together, a novel lipidomic LC/MS platform based on chromatographic retention, high mass resolution and accuracy, MS/MS analysis, and quantitation software enables analysis of complex samples as demonstrated for lipid droplets. PMID:21960706

Fauland, Alexander; Kofeler, Harald; Trotzmuller, Martin; Knopf, Astrid; Hartler, Jurgen; Eberl, Anita; Chitraju, Chandramohan; Lankmayr, Ernst; Spener, Friedrich

2011-01-01

285

Analysis of water from the Space Shuttle and Mir Space Station by ion chromatography and capillary electrophoresis  

NASA Technical Reports Server (NTRS)

Drinking water and condensate samples collected from the US Space Shuttle and the Russian Mir Space Station are analyzed routinely at the NASA-Johnson Space Center as part of an ongoing effort to verify water quality and monitor the environment of the spacecraft. Water quality monitoring is particularly important for the Mir water supply because approximately half of the water consumed is recovered from humidity condensate. Drinking water on Shuttle is derived from the fuel cells. Because there is little equipment on board the spacecraft for monitoring the water quality, samples collected by the crew are transported to Earth on Shuttle or Soyuz vehicles, and analyzed exhaustively. As part of the test battery, anions and cations are measured by ion chromatography, and carboxylates and amines by capillary electrophoresis. Analytical data from Shuttle water samples collected before and after several missions, and Mir condensate and potable recovered water samples representing several recent missions are presented and discussed. Results show that Shuttle water is of distilled quality, and Mir recovered water contains various levels of minerals imparted during the recovery processes as designed. Organic ions are rarely detected in potable water samples, but were present in humidity condensate samples.

Orta, D.; Mudgett, P. D.; Ding, L.; Drybread, M.; Schultz, J. R.; Sauer, R. L.

1998-01-01

286

Separation of polythionates and the gold thiosulfate complex in gold thiosulfate leach solutions by ion-interaction chromatography.  

PubMed

A method for the separation of the polythionates (SxO6(2-), x = 3-5) in gold thiosulfate leach solutions using ion-interaction chromatography with conductivity and ultraviolet (UV) detection is described. Polythionates were eluted within 18 min using an eluent comprising an acetonitrile step gradient at 0.0 min from 15% v/v to 28% v/v, 3 mM TBAOH, and 2.5 mM sodium carbonate, operated using a Dionex NS1-5 micron column with guard. The developed method was capable of separating the gold thiosulfate complex ion in standard solutions, but quantification of this species in realistic leach solutions proved impractical due to a self-elution effect that caused the gold peak to be eluted as a broad band. Detection limits for polythionates using a 10 microL injection volume ranged between 1-6 mg L(-1) (5-23 microM) for conductivity and 0.8-13 mg L(-1) (4-68 microM) for UV detection, based on a signal-to-noise ratio of 2. Calibration was linear over the ranges 5-2000, 10-2000 and 25-2500 mg L(-1) for trithionate, tetrathionate and pentathionate, respectively. The technique was applied successfully to leach liquors containing 0.5 M ammonium thiosulfate, 2 M ammonia, 0.05 M copper sulfate and 20 % m/v gold ore. PMID:12173648

O'Reilly, John W; Shaw, Matthew J; Dicinoski, Greg W; Grosse, Andrew C; Miura, Yasuyuki; Haddad, Paul R

2002-07-01

287

Analysis of water from the Space Shuttle and Mir Space Station by ion chromatography and capillary electrophoresis.  

PubMed

Drinking water and condensate samples collected from the US Space Shuttle and the Russian Mir Space Station are analyzed routinely at the NASA-Johnson Space Center as part of an ongoing effort to verify water quality and monitor the environment of the spacecraft. Water quality monitoring is particularly important for the Mir water supply because approximately half of the water consumed is recovered from humidity condensate. Drinking water on Shuttle is derived from the fuel cells. Because there is little equipment on board the spacecraft for monitoring the water quality, samples collected by the crew are transported to Earth on Shuttle or Soyuz vehicles, and analyzed exhaustively. As part of the test battery, anions and cations are measured by ion chromatography, and carboxylates and amines by capillary electrophoresis. Analytical data from Shuttle water samples collected before and after several missions, and Mir condensate and potable recovered water samples representing several recent missions are presented and discussed. Results show that Shuttle water is of distilled quality, and Mir recovered water contains various levels of minerals imparted during the recovery processes as designed. Organic ions are rarely detected in potable water samples, but were present in humidity condensate samples. PMID:9615408

Orta, D; Mudgett, P D; Ding, L; Drybread, M; Schultz, J R; Sauer, R L

1998-04-24

288

Isotope analysis of sulfur, bromine, and chlorine in individual anionic species by ion chromatography/multicollector-ICPMS.  

PubMed

We developed an analytical method for precise and accurate analysis of ?(34)S, ?(81)Br, and ?(37)Cl in individual anionic species by coupled ion chromatography (IC) and multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The method is based on the online separation and purification of ions by IC prior to their isotope analysis by MC-ICPMS. The developed technique significantly simplifies ?(34)S, ?(81)Br, and ?(37)Cl analysis in environmental samples. In cases when several anionic species of the same element are present in the sample, they might be analyzed in a single analytical run. Major isobaric interferences for the analyzed elements were reduced by using "dry" plasma conditions and applying sufficient mass resolution power. The sample-standard bracketing technique was used for instrumental drift correction. In the case of ?(34)S analysis, precisions up to 0.15‰ (1sd) have been achieved for analytes containing down to 5 nmol of S; for ?(81)Br, the attained precision was 0.1‰ (1sd) for analytes containing down to 0.6 nmol of Br. Precisions of 0.2‰ have been obtained for ?(37)Cl with analytes containing 0.7 ?mol of Cl. Robustness of the developed analytical method, as well as high precisions and accuracies, has been demonstrated for the laboratory standard solutions and for environmental samples. PMID:24893134

Zakon, Yevgeni; Halicz, Ludwik; Gelman, Faina

2014-07-01

289

Photodissociation/gas diffusion/ion chromatography system for determination of total and labile cyanide in waters  

SciTech Connect

An automated system for determination of total and labile cyanide in water samples has been developed. The stable metal-cyanide complexes such as Fe(CN){sub 6}{sup 3{minus}} are photodissociated in an acidic medium with an on-line pyrex glass reaction coil irradiated by an intense Hg lamp. The released cyanide (HCN) is separated from most interferences in the sample matrix and is collected in a dilute NaOH solution by gas diffusion using a hydrophobic porous membrane separator. The cyanide ion is then separated from remaining interferences such as sulfide by ion exchange chromatography and is detected by an amperometric detector. The characteristics of the automated system were studied with solutions of free cyanide and metal-cyanide complexes. The results of cyanide determination for a number of wastewater samples obtained with the new method were compared with those obtained with the standard method. The sample throughput of the system is eight samples per hour and the detection limit for total cyanide is 0.1 {mu}g/L.

Liu, Yan; Rocklin, R.D.; Joyce, R.J.; Doyle, M.J. (Dionex Corporation, Sunnyvale, CA (USA))

1990-04-01

290

Ion chromatography-mass spectrometry: a review of recent technologies and applications in forensic and environmental explosives analysis.  

PubMed

The development and application of ion chromatography (IC) coupled to mass spectrometry (MS) is discussed herein for the quantitative determination of low-order explosives-related ionic species in environmental and forensic sample types. Issues relating to environmental explosives contamination and the need for more confirmatory IC-MS based applications in forensic science are examined. In particular, the compatibility of a range of IC separation modes with MS detection is summarised along with the analytical challenges that have been overcome to facilitate determinations at the ng-?g L(-1) level. Observed trends in coupling IC to inductively coupled plasma and electrospray ionisation mass spectrometry form a particular focus. This review also includes a discussion of the relative performance of reported IC-MS methods in comparison to orthogonal ion separation-based, spectrometric and spectroscopic approaches to confirmatory detection of low-order explosives. Finally, some promising areas for future research are highlighted and discussed with respect to potential IC-MS applications. PMID:24331039

Barron, Leon; Gilchrist, Elizabeth

2014-01-01

291

Poly(ethylene oxide)-bonded stationary phase for separation of inorganic anions in capillary ion chromatography.  

PubMed

A tosylated-poly(ethylene oxide) (PEO) reagent was reacted with primary amino groups of an aminopropylsilica packing material (TSKgel NH2-60) in acetonitrile to form PEO-bonded stationary phase. The reaction was a single and simple step reaction. The prepared stationary phase was able to separate inorganic anions. The retention behavior of six common inorganic anions on the prepared stationary phase was examined under various eluent conditions in order to clarify its separation/retention mechanism. The elution order of the tested anions was iodate, bromate, bromide, nitrate, iodide, and thiocyanate, which was similar as observed in common ion chromatography. The retention of inorganic anions could be manipulated by ion exchange interaction which is expected that the eluent cation is coordinated among the PEO chains and it works as the anion-exchange site. Cations and anions of the eluent therefore affected the retention of sample anions. We demonstrated that the retention of the analyte anions decreased with increasing eluent concentration. The repeatability of retention time for the six anions was satisfactory on this column with relative standard deviation values from 1.1 to 4.3% when 10mM sodium chloride was used as the eluent. Compared with the unmodified TSKgel NH2-60, the prepared stationary phase retained inorganic anions more strongly and the selectivity was also improved. The present stationary phase was applied for the determination of inorganic anions contained in various water samples. PMID:23659983

Linda, Roza; Lim, Lee Wah; Takeuchi, Toyohide

2013-06-14

292

The determination of the Fe sup 2+ /Fe sup 3+ ratio in simulated nuclear waste glass by ion chromatography  

SciTech Connect

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass in the Defense Waste Processing Facility (DWPF). In this facility, control of the oxidation/reduction (redox) equilibrium in the glass melter is critical for processing of the nuclear waste. Therefore, the development of a rapid and reliable analytical method for the determination of the redox equilibrium is of considerable interest. Redox has been determined by measuring the ratio of ferrous to ferric ions in the glass melt. Two analytical techniques for glass redox measurement have been investigated for the DWPF: Mossbauer Spectroscopy which may be subject to interferences from the radiation in actual waste, and a rapid and simple chemical dissolution/spectrophotometric technique. Comparisons of these techniques have been made at several laboratories including Clemson University. In the study attached, the determination of the redox ratio by Ion Chromatography (IC) was investigated as a potential new technology. Clemson University performed IC analyses on the same glasses as previously examined by wet chemical and Mossbauer techniques. Results from all three techniques were highly correlated and IC was reported to be a promising new technology for redox measurement. 19 refs., 19 figs., 5 tabs.

Jantzen, C.M.

1990-10-01

293

Formation of Iron Complexes from Trifluoroacetic Acid Based Liquid Chromatography Mobile Phases as Interference Ions in LC-ESI-MS Analysis  

PubMed Central

Two unexpected singly charged ions at m/z 1103 and 944 have been observed in mass spectra obtained from electrospray ionization-mass spectrometric analysis of liquid chromatography effluents with mobile phases containing trifluoroacetic acid that severely interfered with sample analysis. Accurate mass measurement and tandem mass spectrometry studies revealed that these two ions are composed of three components; clusters of trifluoroacetic acid, clusters of mass 159 and iron. Formation of these ions is inhibited by removing trifluoroacetic acid from the mobile phases and using formic acid in its place, replacing the stainless steel union with a titanium union or by adding a small blank fused silica capillary column between the chromatography column and the electrospray tip via a stainless steel union without any adverse effects to chromatographic separation, peak broadening or peptide identifications. PMID:21504012

Shukla, Anil; Zhang, Rui; Orton, Daniel; Zhao, Rui; Clauss, Therese; Moore, Ronald; Smith, Richard

2011-01-01

294

Determination of ammonium in a buddingtonite sample by ion-chromatography  

USGS Publications Warehouse

An ion-chromatographic method for the direct determination of ammonium, potassium, and sodium in geologic materials is described. Samples are decomposed with a mixture of hydrofluoric and hydrochloric acids in a sealed polycarbonate bottle heated in a microwave oven. The ion-chromatograph separates the cations and determines them by conductivity measurement. The ammonium concentrations thus determined have been verified by use of an ammonia-specific electrode. A total of 32 analyses of ammonium salts by both techniques showed an average error of -4%, with a relative standard deviation (RSD) of 6%. The ammonium concentrations found in a buddingtonite sample had an RSD of 2.2% and their mean agreed with that obtained by the Kjeldahl method. By use of the prescribed dilution of the sample, detection limits of 0.1% can be achieved for all three cations. ?? 1986.

Klock, P. R.; Lamothe, P. J.

1986-01-01

295

Metabolic profiling of flavonoids in Lotus japonicus using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

Flavonoids detected from a model legume plant, Lotus japonicus accessions Miyakojima MG-20 and Gifu B-129, were profiled using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR/MS). Five flavonols and two anthocyanidins were detected as aglycones. LC-FTICR/MS facilitated simultaneous detection of 61 flavonoids including compounds that have not been reported previously. Chemical information of the peaks such as retention time, lambdamax, m/z value of the quasi-molecular ion, m/z value of MS/MS fragment ions, and relative intensity of MS/MS fragments was obtained, along with the molecular formulas and conjugate structures. Fourteen were completely identified by comparison with authentic compounds. The high accuracy of m/z values, being 0.081 ppm between observed and theoretical values, allowed prediction of molecular formulas of unknown compounds with the help of isotope peak information for determination of chemical composition. Based on a predicted elemental composition, the presence of a novel nitrogen-containing flavonoid was proposed. A comparison of flavonoid profiles in flowers, stems, and leaves demonstrated that the flowers yielded the most complex profile, containing 30 flower-specific flavonoids including gossypetin glycosides and isorhamnetin glycosides. A comparison of flavonoid profiles between MG-20 and B-129 grown under the same conditions revealed that the accumulation of anthocyanins was higher in B-129 than MG-20, particularly in the stem. Developmental changes in the flavonoid profiles demonstrated that kaempferol glycosides increased promptly after germination. In contrast, quercetin glycosides, predominant flavonoids in the seeds, were not detectable in growing leaves. PMID:17669449

Suzuki, Hideyuki; Sasaki, Ryosuke; Ogata, Yoshiyuki; Nakamura, Yukiko; Sakurai, Nozomu; Kitajima, Mariko; Takayama, Hiromitsu; Kanaya, Shigehiko; Aoki, Koh; Shibata, Daisuke; Saito, Kazuki

2008-01-01

296

SEPARATION OF PHENYLARSONIC COMPOUNDS BY ION PAIRING-REVERSED PHASE-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY  

Microsoft Academic Search

Phenylarsonic compounds are extensively used as feed additives to promote growth and to control disease in the poultry industry. A method was conducted that allowed the analysis of arsenic animal feed additives by ion pairing-reversed phase HPLC (IP-RP-HPLC) with a UV detection using an octadecylsilylsilica column. The separation of anionic arsenic compounds (3-nitro-4-hydroxyphenylarsonic acid (3-NHPAA), p-arsanilic acid (p-ASA) and phenylarsonic

JAFARIAH JAAFAR

297

Paper Chromatography of Alkaloids Using Liquid Ion Exchangers as Developing Solvents  

Microsoft Academic Search

The RF vs. pH relationships of a number of more important alkaloids were determined for several solvent systems of the type oleic acid + diluting solvent\\/aqueous buffer solutions. The chromatographic data seem to indicate a high solvent power of the organic phase, belonging to the class of liquid ion exchangers. The regular RF vs. pH relationships obtained can be quantitatively

Edward Soczewi?aski; Grazyna Matysik; Halina Szumilo

1967-01-01

298

Comparison of gasolines using gas chromatography-mass spectrometry and target ion response.  

PubMed

Gas chromatography-mass spectrometry was used to compare gasoline samples obtained from different sources based on the difference in amounts of certain components found in the headspace of gasoline using target response data. Many suspected arson cases involve comparing an ignitable liquid extracted from fire debris to a liquid found in a suspect's possession to determine if they could have had a common source. Various component ratios are proposed for determining if an unevaporated gasoline sample could have originated from the same source as an evaporated gasoline extracted from fire debris. Fifty and 75% evaporated gasoline samples were both found to contain similar ratios of certain components when compared with its unevaporated source gasoline. The results of the comparisons in this study demonstrate that for cases involving gasoline that has been evaporated up to 50% and extracted from pine, it is possible to eliminate comparison samples as originating from the same source. The results of the 75% comparisons suggest it may be possible to apply the same type of comparison to cases involving 75% evaporated gasoline. PMID:15461104

Barnes, Aisha T; Dolan, Julia A; Kuk, Raymond J; Siegel, Jay A

2004-09-01

299

Continuous processing of recombinant proteins: integration of refolding and purification using simulated moving bed size-exclusion chromatography with buffer recycling.  

PubMed

Continuous processing of recombinant proteins was accomplished by combining continuous matrix-assisted refolding and purification by tandem simulated moving bed (SMB) size-exclusion chromatography (SEC). Recombinant proteins, N(pro) fusion proteins from inclusion bodies were dissolved with NaOH and refolded in the SMB system with a closed-loop set-up with refolding buffer as the desorbent buffer and buffer recycling of the refolding buffer of the raffinate by tangential flow filtration. For further purification of the refolded proteins, a second SMB operation also based on SEC was added. The whole system could be operated isocratically with refolding buffer as the desorbent buffer, and buffer recycling could also be applied in the purification step. Thus, a significant reduction in buffer consumption was achieved. The system was evaluated with two proteins, the N(pro) fusion pep6His and N(pro) fusion MCP-1. Refolding solution, which contained residual N(pro) fusion peptide, the cleaved autoprotease N(pro), and the cleaved target peptide was used as feed solution. Full separation of the cleaved target peptide from residual proteins was achieved at a purity and recovery in the raffinate and extract, respectively, of approximately 100%. In addition, more than 99% of the refolding buffer of the raffinate was recycled. A comparison of throughput, productivity, and buffer consumption of the integrated continuous process with two batch processes demonstrated that up to 60-fold higher throughput, up to 180-fold higher productivity, and at least 28-fold lower buffer consumption can be obtained by the integrated continuous process, which compensates for the higher complexity. PMID:24630055

Wellhoefer, Martin; Sprinzl, Wolfgang; Hahn, Rainer; Jungbauer, Alois

2014-04-11

300

Branched polymers characterized by comprehensive two-dimensional separations with fully orthogonal mechanisms: Molecular-topology fractionation×size-exclusion chromatography.  

PubMed

Polymer separations under non-conventional conditions have been explored to obtain a separation of long-chain branched polymers from linear polymers with identical hydrodynamic size. In separation media with flow-through channels of the same order as the size of the analyte molecules in solution, the separation and the elution order of polymers are strongly affected by the flow rate. At low flow rates, the largest polymers are eluted last. At high flow rates, they are eluted first. By tuning the channel size and flow rate, conditions can be found where separation becomes independent of molar mass or size of linear polymers. Long-chain branched polymers did experience lower migration rates under these conditions and can be separated from linear polymers. This type of separation is referred to as molecular-topology fractionation (MTF) at critical conditions. Separation by comprehensive two-dimensional molecular-topology fractionation and size-exclusion chromatography (MTF×SEC) was used to study the retention characteristics of MTF. Branching selectivity was demonstrated for three- and four-arm "star" polystyrenes of 3-5×10(6)g/mol molar mass. Baseline separation could be obtained between linear polymer, Y-shaped molecules, and X-shaped molecules in a single experiment at constant flow rate. For randomly branched polymers, the branching selectivity inevitably results in an envelope of peaks, because it is not possible to fully resolve the huge numbers of different branched and linear polymers of varying molar mass. It was concluded that MTF involves partial deformation of polymer coils in solution. The increased coil density and resistance to deformation can explain the different retention behavior of branched molecules. PMID:25282310

Edam, Rob; Mes, Edwin P C; Meunier, David M; Van Damme, Freddy A; Schoenmakers, Peter J

2014-10-31

301

Removal of heavy metal ions from aquatic solutions by membrane chromatography  

Microsoft Academic Search

Polyvinylalcohol membranes were prepared by a solvent casting technique. Metal-complexation ligand, i.e. monochlorotriazinyl-dye Cibacron Blue F3GA was then attached. These membranes with a high water content of 119%, and containing 8.7 mmol Cibacron Blue F3GA\\/m2 were used in the adsorption\\/stripping of some selected heavy metal ions [Cu(II), Hg(II), Pb(II) and Cd(II)] from aquatic solutions containing varying initial concentration of metal

Adil Denizli; Ridvan Say; Yakup Arica

2000-01-01

302

Semiautomated pH Gradient Ion-Exchange Chromatography of Monoclonal Antibody Charge Variants.  

PubMed

A new approach using a chromatography system equipped with isocratic pumps and an electrolytic eluent generator (EG) is introduced, replacing external pH gradient delivery using conventional gradient systems, in which bottled buffers with preadjusted pH are mixed using a gradient pump. The EG is capable of generating high purity base or acid required for online preparation of the buffer at the point of use, utilizing deionized water as the only carrier stream. Typically, the buffer was generated from online titration of a reagent composed of low molecular weight amines. The reagent was delivered isocratically into a static mixing tee, where it was titrated to the required pH with electrolytically generated base or acid. The required pH gradient was thus conveniently generated by electrically controlling the concentration of titrant. Also, since the pH was adjusted at the point of use, this approach offered enhanced throughput in terms of eluent preparation time and labor, and with a more reproducible pH profile. The performance of the system was demonstrated by running pH gradients ranging from pH 8.2 to 10.9 on a polymer monolith cation-exchange column for high throughput profiling of charge heterogeneity of intact, basic therapeutic monoclonal antibodies. A high degree of flexibility in modulating the key parameters of the pH gradient, including the buffer concentration, the pH gradient slope and the operating pH range was demonstrated. This enabled fine-tuning of the separation conditions for each individual antibody in order to enhance the chromatographic resolution. PMID:25199803

Talebi, Mohammad; Shellie, Robert A; Hilder, Emily F; Lacher, Nathan A; Haddad, Paul R

2014-10-01

303

Matrix effects in the determination of bromate in drinking water by ion chromatography.  

PubMed

Bromate is a well known by-product produced by the ozonation of drinking water; the allowed concentration for human consumption has to be regulated to low microgram l-1 range. By using a high-capacity anion-exchange column, it should be possible to determine bromate at this low concentration by direct injection of a very large volume (up to 1 ml) without any sample preconcentration and pretreatment. The feasibility of this technique for the determination of bromate in drinking water has been explored in our work. The experimental results showed that matrix effect, due to inorganic ions contained in drinking water, strongly influenced the chromatographic behaviour of the bromate peak. The increase of the total ion content led to a correlated decrease in the efficiency of the analyte peak so that effective detection limits depended on the matrix composition. In this work chromatographic parameters (efficiency, asymmetry and resolution) of bromate peak are discussed in relation to the concentration of the main inorganic anions, and the injection volume (from 250 microliters to 1 ml). PMID:10431365

Colombini, S; Polesello, S; Valsecchi, S; Cavalli, S

1999-06-25

304

Inhibition, reactivation, and determination of metal ions in membrane metalloproteases of bacterial origin using high-performance liquid chromatography coupled on-line with inductively coupled plasma mass spectrometry.  

PubMed

High-performance liquid chromatography coupled on-line with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used for the characterization of metal ions in several metalloproteases of bacterial origin. The different components of the bacterial extracts were separated on a size-exclusion column. The eluent of the HPLC system was continuously transported to the ICP-MS system for rapid, reproducible, and sensitive analyses of trace elements in the metalloproteases. Two different membrane proteases from Bacillus cereus and Pseudomonas aeruginosa were characterized to be zinc metalloproteases using enzymological methods and HPLC-ICP-MS. The zinc content was determined to be three molecules of zinc per protein molecule for the B. cereus protease and one molecule of zinc per protein molecule for the P. aeruginosa protease. For another purified protease, a periplasmic alanyl aminopeptidase of P. aeruginosa, the lack of protein-bound metal ions could be clearly determined-a confirmation that this main aminopeptidase of P. aeruginosa belongs to the cysteine protease family. The presence of nonionic detergents can influence the distribution of trace elements during the HPLC separation. Therefore, the use of these substances should be avoided during enzyme purification for metal analyses or they should be exchanged later for zwitterionic and ionic detergents with more strongly dissociating properties. PMID:9344414

Leopold, I; Fricke, B

1997-10-15

305

Diffusion scrubber-ion chromatography for the measurement of trace levels of atmospheric HCl  

NASA Astrophysics Data System (ADS)

A diffusion scrubber-ion chromatographic (DS-IC) instrument has been characterized and employed for the measurement of trace levels of gaseous HCl in the atmosphere. The instrument operates with a temporal resolution of 5 min and the detection limit is estimated to be 5 pptv. Collection efficiencies for HCl with two identical diffusion scrubbers were 28±2% and 20±2%, respectively, at a sampling flow rate of 2 SLPM. Instrument response decreases with increased relative humidity. An equation, correction factor=2.45 × 10 -7 × %r.h 3 + 1.00, is used to correct for the relative humidity dependency. The instrument was tested in ambient air studies by measuring background mixing ratios between 0.02 and 0.5 ppbv at a suburban sampling site. Calibration of the instrument was carried out with a novel source of gaseous HCl based on sublimation of ammonium chloride.

Lindgren, Per F.

306

Automated determination of bromide in waters by ion chromatography with an amperometric detector  

USGS Publications Warehouse

An automated ion chromatograph, including a program controller, an automatic sampler, an integrator, and an amperometric detector, was used to develop a procedure for the determination of bromide in rain water and many ground waters. Approximately 10 min is required to obtain a chromatogram. The detection limit for bromide is 0.01 mg l-1 and the relative standard deivation is <5% for bromide concentrations between 0.05 and 0.5 mg l-1. Chloride interferes if the chloride-to-bromide ratio is greater than 1 000:1 for a range of 0.01-0.1 mg l-1 bromide; similarly, chloride interferes in the 0.1-1.0 mg l-1 range if the ratio is greater than 5 000:1. In the latter case, a maximum of 2 000 mg l-1 of chloride can be tolerated. Recoveries of known concentrations of bromide added to several samples, ranged from 97 to 110%. ?? 1983.

Pyen, G. S.; Erdmann, D. E.

1983-01-01

307

Impurity profiling of etimicin sulfate by liquid chromatography ion-trap mass spectrometry.  

PubMed

A reversed phase (RP)-LC method using a C(18) column resistant to basic pH and an alkaline (pH 10) aqueous mobile phase was developed and coupled to MS with an electrospray ionization (ESI) source in the positive ion mode which provides MS(n) capability. In total, 26 impurities were detected in a commercial sample. The structures of the impurities were proposed based on comparison of their fragmentation patterns with those of the available reference substances, the synthetic route and literature data. Starting material and its residual impurities, intermediates, synthetic by-products and degradation products were the main sources of those impurities. 14 impurities described in this work were newly identified. PMID:22819209

Yuan, Yao-zuo; Zhang, Mei; Fan, Xia-Lei; Wang, Guo-Hua; Hu, Chang-Qing; Jin, Shao-hong; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

2012-11-01

308

Ion-pair chromatography for simultaneous analysis of ethionamide and pyrazinamide from their porous microparticles.  

PubMed

Ethionamide (ETA) and pyrazinamide (PZA) are considered the drugs of choice for the treatment of multidrug-resistant tuberculosis. Current methods available in the literature for simultaneous determination of ETA and PZA have low sensitivity or involve column modifications with lipophilic cations. The aim of this study was to develop a simple and validated reversed-phase ion-pair HPLC method for simultaneous determination of ETA and PZA for the characterization of polymeric-based porous inhalable microparticles in in vitro and spiked human serum samples. Chromatographic separation was achieved on a Phenomenex C18 column (250 mm?×?4.6 mm) using a Shimadzu LC 10 series HPLC. The mobile phase consisted of A: 0.01% trifluoroacetic acid in distilled water and B: ACN/MeOH at 1:1 v/v. Gradient elution was run at a flow rate of 1.5 mL/min and a fixed UV wavelength of 280 nm. The validation characteristics included accuracy, precision, linearity, analytical range, and specificity. Calibration curves at seven levels for ETA and PZA were linear in the analytical range of 0.1-3.0 ?g/mL with correlation coefficient of r (2)?>?0.999. Accuracy for both ETA and PZA ranged from 94 to 106% at all quality control (QC) standards. The method was precise with relative standard deviation less than 2% at all QC levels. Limits of quantitation for ETA and PZA were 50 and 70 ng/mL, respectively. There was no interference from either the polymeric matrix ions or the biological matrix in the analysis of ETA and PZA. PMID:23990078

Bhanushali, Chintan J; Zidan, Ahmed S; Rahman, Ziyaur; Habib, Muhammad J

2013-12-01

309

Determination of nitrosamines in water by gas chromatography/chemical ionization/selective ion trapping mass spectrometry.  

PubMed

A gas chromatography/mass spectrometry (GC/MS) method for determination of nine N-nitrosamines (NAs) in water is described. Two ionization modes, electron impact (EI) and chemical ionization (CI) with methanol, as well as different ion analysis techniques, i.e. full scan, selected ion storage (SIS) and tandem mass spectrometry (MS/MS) were tested. Chemical ionization followed by SIS resulted the mass spectrometric method of choice, with detection limits in the range of 1-2ng/L. Solid Phase Extraction (SPE) with coconut charcoal cartridges was applied to extract NAs from real samples, according EPA Method 521. Drinking water samples were collected from seven surface- and two groundwater treatment plants. Three surface water treatment plants were sampled before and after addition of O(3)/ClO(2) to observe the effect of disinfection on NAs' formation. N-nitrosodiethylamine (NDEA), n-nitrosodipropylamine (NDPA), n-nitrosomorpholine (NMOR) and n-nitrosodibutylamine (NDBA) were found up to concentrations exceeding three times the risk level of 10ng/L set by the California Department of Public Health. Because dermal adsorption has been recently indicated as a new contamination route of exposure to NAs for people who practice swimming activity, water samples from five swimming pools in the Bologna (Italy) area were collected. N-nitrosopyrrolidine (NPYR) was detected in all samples at concentrations larger than 50ng/L, likely as a disinfection by-product from the amino acid precursor proline, a main constituent of skin collagen. PMID:21377686

Pozzi, Romina; Bocchini, Paola; Pinelli, Francesca; Galletti, Guido C

2011-04-01

310

Potential of ion chromatography coupled to isotope ratio mass spectrometry via a liquid interface for beverages authentication.  

PubMed

New tools for the determination of characteristic parameters for food authentication are requested to prevent food adulteration from which health concerns, unfair competition could follow. A new coupling in the area of compound-specific carbon 13 isotope ratio (?(13)C) analysis was developed to simultaneously quantify ?(13)C values of sugars and organic acids. The coupling of ion chromatography (IC) together with isotope ratio mass spectrometry (IRMS) can be achieved using a liquid interface allowing a chemical oxidation (co) of organic matter. Synthetic solutions containing 1 polyol (glycerol), 3 carbohydrates (sucrose, glucose and fructose) and 12 organic acids (gluconic, lactic, malic, tartaric, oxalic, fumaric, citric and isocitric) were used to optimize chromatographic conditions (concentration gradient and 3 types of column) and the studied isotopic range (-32.28 to -10.65‰) corresponds to the values found in food products. Optimum chromatographic conditions are found using an IonPac AS15, an elution flow rate of 0.3mLmin(-1) and a linear concentration gradient from 2 to 76mM (rate 21mMmin(-1)). Comparison between ?(13)C value individually obtained for each compound with the coupling IRMS and elemental analyzer, EA-IRMS, and the ones measured on the mixture of compounds by IC-co-IRMS does not reveal any isotope fractionation. Thus, under these experimental conditions, IC-co-IRMS results are accurate and reproducible. This new coupling was tested on two food matrices, an orange juice and a sweet wine. Some optimization is necessary as the concentration range between sugars and organic acids is too large: an increase in the filament intensity of the IRMS is necessary to simultaneously detect the two compound families. These first attempts confirm the good results obtained on synthetic solutions and the strong potential of the coupling IC-co-IRMS in food authentication area. PMID:24267317

Guyon, Francois; Gaillard, Laetitia; Brault, Audrey; Gaultier, Nicolas; Salagoïty, Marie-Hélène; Médina, Bernard

2013-12-27

311

Liquid chromatography of carboxylic acids using potentiometric detection with a tungsten oxide electrode  

Microsoft Academic Search

A tungsten oxide electrode was evaluated for potentiometric detection of carboxylic acids separated using various liquid Chromatographic methods, such as reversed-phase, ion-interaction and ion-exclusion. The separation of formic, acetic, propionic and butyric acids was performed using reversed-phase chromatography with 10% methanol\\/water solution at pH 6.0 as the eluent. The calibration plots were linear in the range 0.5–3.0 mmol, and the

ZuLiang Chen; Peter W. Alexander; Paul R. Haddad

1997-01-01

312

Differentiation of the halogen content of peat samples using ion chromatography after combustion (TX/TOX-IC).  

PubMed

The proposed method for the differential AOX analysis of water samples was tested for its applicability to differentiate the halogen content of peat samples. For determination of the total and the total organic-bound chlorine, bromine and iodine, peat samples were combusted, and the combustion gases trapped and analyzed by ion chromatography (TX/TOX-IC). The total and the organically bound chlorine, bromine and iodine, respectively, can be determined by two-fold analysis with deviations of around 10%. With respect to chlorine more than a double determination could be required. The limit of quantification is 20 mg kg(-1) for chlorine, 2 mg kg(-1) for bromine and 1 mg kg(-1) for iodine, if 25 mg of peat is combusted. The most crucial step of the analysis is the inorganic halogen removal, which is necessary if the organically bound fraction is determined. However, there are some uncertainties about the complete removal of the inorganic halides from the solid samples. Thus, the values of the organically bound fraction have to be discussed as maximal concentrations. Nevertheless, we suggest that the applied method can be useful as a tool for studying the fate of halogens in soils. PMID:12664178

Putschew, Anke; Keppler, Frank; Jekel, Martin

2003-03-01

313

Investigation of a fusion technique for the determination of total sulfur in geological samples by ion chromatography  

SciTech Connect

The authors have encountered the need for a rapid, accurate, precise, and sensitive method for measuring total sulfur in large numbers of geological samples. Numerous environmental studies of sulfur deposition due to sulfur dioxide emission from combustion and industry are currently under way. Several techniques for measuring total sulfur in soils and other silicate materials have been published including neutron activation analysis, thermal neutron capture prompt ..gamma..-ray spectrometry, inductively coupled plasma atomic emission spectrometry, isotope dilution mass spectrometry, X-ray fluorescence, turbidimetry, ion chromatography (IC), iodimetric titration, and fluorometry. However, none of these methods is completely satisfactory for routine analysis of large numbers of samples. Many have levels of detection that are inadequate for measuring low levels of total sulfur (<100 ..mu..g/g) often encountered in soils. Several utilize only aqueous extracts of the soils and do not provide a total sulfur determination. Others require extensive sample preparation, are susceptible to loss of sulfur during oxidation, or produce incomplete conversion of sulfur species to sulfate. The objective of this work was to evaluate the accuracy of IC determination of sulfate for Na/sub 2/O/sub 2/ soil fusions by comparing the results obtained for reference materials with literature values reported for other techniques. They were also interested in determining if this fusion method would be rapid enough to handle large numbers of samples.

Stallings, E.A.; Candelaria, L.M.; Gladney, E.S.

1988-06-01

314

Determination of spiroxamine residues in grapes, must, and wine by gas chromatography/ion trap-mass spectrometry.  

PubMed

Analytical methodology was developed and validated for the determination of spiroxamine residues in grapes, must, and wine by gas chromatography/ion trap-mass spectrometry (GC/IT-MS). Two extraction procedures were used: the first involved grapes, must, and wine extraction with alkaline cyclohexane-dichloromethane (9 + 1, v/v) solution, and the second grape extraction with acetone, dichloromethane, and petroleum ether. In both procedures, the extract was centrifuged, evaporated to dryness, and reconstituted in cyclohexane or 2,2,4-trimethylpentane-toluene (9 + 1, v/v), respectively. Spiroxamine diastereomers A and B were determined by GC/IT-MS, and a matrix effect was observed in the case of grapes but not in must and wine. Recovery of spiroxamine from fortified samples at 0.02 to 5.0 mg/kg ranged from 78-102% for grapes and must, with relative standard deviation (RSD) <13%; for red and white wines, recoveries ranged from 90 to 101% with RSD <9%. The limit of quantification was 0.02 mg/kg for grapes, must, and wine or 0.10 mg/kg for grapes, depending on the extraction procedure used. PMID:16526469

Tsiropoulos, Nicholas G; Liapis, Konstantinos; Likas, Dimitrios T; Miliadis, George E

2005-01-01

315

Fast carbohydrate analysis via liquid chromatography coupled with ultra violet and electrospray ionization ion trap detection in 96-well format.  

PubMed

A fast carbohydrate screening platform processible in 96-well format is described. The method is suitable for the determination of various carbohydrates out of complex mixtures as obtained by acidic hydrolysis of carbohydrates polymers. The chromatographic conditions for an efficient separation (12min) and the derivatization process with 1-phenyl-3-methyl-5-pyrazolone (PMP) were optimized for high resolution separation and simultaneous determination of deoxy-, amino-, anhydro-sugars as well as hexoses, pentoses, dimers, uronic acids and degradation products like furfural and hydroxymethylfurfural (HMF). The potential to quantify with UV- and MS-detector in the same range has been demonstrated for 20 different compounds. Finally, the matrix effects of the hydrolysis were positively evaluated. The micro scale hydrolysis and PMP-derivatization without any extraction or drying steps, both in 96-well format, result in a fast and intuitive sample preparation. In combination with a fast liquid chromatography coupled to UV and electrospray ionization ion trap detection (LC-UV-ESI-MS/MS) for the qualification and quantification of various sugars, dimers and degradation products, this method shows great performance in carbohydrate analysis. PMID:24861788

Rühmann, Broder; Schmid, Jochen; Sieber, Volker

2014-07-11

316

Determination of arsenic speciation in sulfidic waters by Ion Chromatography Hydride-Generation Atomic Fluorescence Spectrometry (IC-HG-AFS).  

PubMed

A method for the analysis of arsenic species in aqueous sulfide samples is presented. The method uses an ion chromatography system connected with a Hydride-Generation Atomic Fluorescence Spectrometer (IC-HG-AFS). With this method inorganic As(III) and As(V) species in water samples can be analyzed, including arsenite (HnAs(III)O3(n-3)), thioarsenite (HnAs(III)S3(n-3)), arsenate (HnAs(V)O4(n-3)), monothioarsenate (HnAs(V)SO3(n-3)), dithioarsenate (HnAs(V)S2O2(n-3)), trithioarsenate (HnAs(V)S3O(n-3)) and tetrathioarsenate (HnAs(V)S4(n-3)). The peak identification and retention times were determined based on standard analysis of the various arsenic compounds. The analytical detection limit was ~1-3 µg L(-1) (LOD), depending on the quality of the baseline. This low detection limit makes this method also applicable to discriminate between waters meeting the drinking water standard of max. 10 µg L(-1) As, and waters that do not meet this standard. The new method was successfully applied for on-site determination of arsenic species in natural sulfidic waters, in which seven species were unambiguously identified. PMID:25059187

Keller, Nicole S; Stefánsson, Andri; Sigfússon, Bergur

2014-10-01

317

Determination of molybdate in environmental water by ion chromatography coupled with a preconcentration method employing a selective chelating resin.  

PubMed

A simple and sensitive suppressed ion chromatography (IC) method with conductivity detection for the determination of molybdate in environmental water is proposed. Molybdate in highly saline water was extracted and preconcentrated. Preconcentration was accomplished by using a chelating resin using a chelating resin immobilized with carboxymethylated polyethylenimine (Presep(®) PolyChelate). This resin is able to trap a variety of metal elements without any interference of alkali and alkaline-earth metals. A 30-mL volume of brackish water was adjusted for appropriate pH and then flushed through 100 mg of the chelating resin. Molybdate concentrated on the resin could be easily eluted with 6 mL of 0.1 M NaOH. A large volume injection method for IC was achieved with in-line neutralization of the effluent. The determination of 0.6 ?g L(-1) molybdate in highly saline water was made possible with a 500-?L injection. Samples of brackish water were taken at various distances from the river mouth. The determined concentrations of molybdate correlated closely with concentrations of chloride. PMID:23149614

Nakashima, Yasuo; Inoue, Yoshinori; Yamamoto, Takahisa; Kamichatani, Waka; Kagaya, Sigehiro; Yamamoto, Atsushi

2012-01-01

318

Rapid analysis of six phthalate esters in wine by ultrasound-vortex-assisted dispersive liquid-liquid micro-extraction coupled with gas chromatography-flame ionization detector or gas chromatography-ion trap mass spectrometry.  

PubMed

An Ultrasound-Vortex-Assisted Dispersive Liquid-Liquid Micro-Extraction (USVADLLME) procedure coupled with Gas Chromatography-Flame Ionization Detector (GC-FID) or Gas Chromatography-Ion Trap Mass Spectrometry (GC-IT/MS) is proposed for rapid analysis of six phthalate esters in hydroalcoholic beverages (alcohol by volume, alc vol(-1), ?40%). Under optimal conditions, the enrichment factor of the six analytes ranges from 220- to 300-fold and the recovery from 85% to 100.5%. The limit of detection (LOD) and limit of quantification (LOQ) are ?0.022 ?g L(-1) and ?0.075 ?g L(-1), respectively. Intra-day and inter-day precisions expressed as relative standard deviation (RSD), are ?8.2% and ?7.0%, respectively. The whole proposed methodology has demonstrated to be simple, reproducible and sensible for the determination of trace phthalate esters in red and white wine samples. PMID:23498123

Cinelli, Giuseppe; Avino, Pasquale; Notardonato, Ivan; Centola, Angela; Russo, Mario Vincenzo

2013-03-26

319

Characterization of the chemical constituents in Da-Huang-Gan-Cao-Tang by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and liquid chromatography coupled with ion trap mass spectrometry.  

PubMed

In this work, the chemical constituents in Da-Huang-Gan-Cao-Tang, a traditional Chinese formula, were studied by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and liquid chromatography coupled with ion trap mass spectrometry for the first time. Among the 146 compounds detected in Da-Huang-Gan-Cao-Tang, 104 compounds were identified unambiguously or tentatively based on their accurate molecular weight and multistage MS data, including one potential novel compound and two reported in Glycyrrhiza genus for the first time. The possible fragmentation pathways were proposed and fragmentation rules of the major types of compounds were concluded. This study provided an example to facilitate the tedious identification of chemical composition in traditional Chinese medicine, and maybe a promising reference approach to research the analogous formulae. PMID:24771648

Wang, Shufang; Chen, Pinghong; Xu, Yimin; Li, Xiaodong; Fan, Xiaohui

2014-07-01

320

Determination of inorganic anions in water by ion chromatography: a collaborative study.  

PubMed

The U.S. Environmental Protection Agency (U.S. EPA) and the American Society for Testing and Materials (ASTM) conducted a joint collaborative study validating an ion chromatographic method for determination fo inorganic anions (U.S. EPA method 300.0A and the equivalent proposed revision to ASTM method D4327). This study was conducted to determine the mean recovery and precision of analyses for bromide, chloride, fluoride, nitrate, nitrite, orthophosphate, and sulfate in reagent water, drinking water, and wastewater. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The test waters were spiked with the anions at 6 concentration levels, prepared as 3 Youden pairs. The 22 volunteer laboratories were instructed to dilute 10 mL sample concentrate to 100 mL test water. A measured volume of sample (20-200 microL) was injected into an ion chromatograph equipped with a guard column, anion exchange column, and a chemical micromembrane suppression device. The anions were then separated using 1.7 mM sodium bicarbonate and 1.8 mM sodium carbonate, and measured by a conductivity detector. Submitted data were evaluated using U.S. EPA's IMVS computer program, which follows ASTM D2777-86 statistical guidance. U.S. EPA method 300.0A and ASTM method D4327 were judged acceptable for measurement of the above anions (except sulfate) at concentrations ranging from 0.3 to 25 mg/L and sulfate concentrations from 2.9 to 95 mg/L. Mean recoveries for the 7 anions from all matrixes, as estimated from the linear regression equations, ranged from 95 to 104%. At concentrations above 2-6 mg/L for bromide, fluoride, nitrate, nitrite, and orthophosphate, and above 24 mg/L for sulfate, the overall and single-analyst relative standard deviations were less than 10 and 6%, respectively. As concentrations decreased, precision became more variable. The relative standard deviations of results for chloride were slightly higher than the other anions, especially in matrixes with high chloride background. Analysis of Variance (ANOVA) tests at the 95% confidence interval indicated a statistically significant matrix effect for chloride, nitrite, and nitrate analyses in drinking water compared to analyses in reagent water. Because these matrix effects were caused by the spiking process and not the drinking water itself, the ANOVA determination was not considered to be of practical significance. PMID:7950425

Edgell, K W; Longbottom, J E; Pfaff, J D

1994-01-01

321

Measurement of gas-phase ammonia and amines in air by collection onto an ion exchange resin and analysis by ion chromatography  

NASA Astrophysics Data System (ADS)

Ammonia and amines are common trace gases in the atmosphere and have a variety of both biogenic and anthropogenic sources, with a major contribution coming from agricultural sites. In addition to their malodorous nature, both ammonia and amines have been shown to enhance particle formation from acids such as nitric, sulfuric and methanesulfonic acids, which has implications for visibility, human health and climate. A key component of quantifying the effects of these species on particle formation is accurate gas-phase measurements in both laboratory and field studies. However, these species are notoriously difficult to measure as they are readily taken up on surfaces, including onto glass surfaces from aqueous solution as established in the present studies. We describe here a novel technique for measuring gas-phase ammonia and amines that involves uptake onto a weak cation exchange resin followed by extraction and analysis using ion chromatography. Two variants - one for parts per billion concentrations in air and the second with lower (parts per trillion) detection limits - are described. The latter involves the use of a custom-designed high-pressure cartridge to hold the resin for in-line extraction. These methods avoid the use of sampling lines, which can lead to significant inlet losses of these compounds. They also have the advantages of being relatively simple and inexpensive. The applicability of this technique to ambient air is demonstrated in measurements made near a cattle farm in Chino, CA.

Dawson, M. L.; Perraud, V.; Gomez, A.; Arquero, K. D.; Ezell, M. J.; Finlayson-Pitts, B. J.

2014-08-01

322

Modeling of salt and pH gradient elution in ion-exchange chromatography.  

PubMed

The separation of proteins by internally and externally generated pH gradients in chromatofocusing on ion-exchange columns is a well-established analytical method with a large number of applications. In this work, a stoichiometric displacement model was used to describe the retention behavior of lysozyme on SP Sepharose FF and a monoclonal antibody on Fractogel SO3 (S) in linear salt and pH gradient elution. The pH dependence of the binding charge B in the linear gradient elution model is introduced using a protein net charge model, while the pH dependence of the equilibrium constant is based on a thermodynamic approach. The model parameter and pH dependences are calculated from linear salt gradient elutions at different pH values as well as from linear pH gradient elutions at different fixed salt concentrations. The application of the model for the well-characterized protein lysozyme resulted in almost identical model parameters based on either linear salt or pH gradient elution data. For the antibody, only the approach based on linear pH gradients is feasible because of the limited pH range useful for salt gradient elution. The application of the model for the separation of an acid variant of the antibody from the major monomeric form is discussed. PMID:24415551

Schmidt, Michael; Hafner, Mathias; Frech, Christian

2014-01-01

323

Automated LC–LC–MS–MS platform using binary ion-exchange and gradient reversed-phase chromatography for improved proteomic analyses  

Microsoft Academic Search

A simple multidimensional liquid chromatography system utilizing an isocratic pump and a HPLC system is described for the comprehensive proteomic analysis of complex peptide digest mixtures by coupled LC–LC–MS–MS techniques. A binary ion-exchange separation was achieved through the use of a strong cation-exchange column followed by a reversed-phase column for data-dependent LC–MS–MS analysis of the unbound analytes, and following salt

Michael T. Davis; Jill Beierle; Edward T. Bures; Michael D. McGinley; Jessica Mort; John H. Robinson; Chris S. Spahr; Wen Yu; Roland Luethy; Scott D. Patterson

2001-01-01

324

Determination of non-ionic polyethoxylated surfactants in wastewater and river water by mixed hemimicelle extraction and liquid chromatography–ion trap mass spectrometry  

Microsoft Academic Search

The capability of hemimicelles-based solid phase extraction (SPE)\\/liquid chromatography\\/atmospheric pressure chemical ionisation in positive mode, ion trap mass spectrometry (LC\\/(APCI+-IT)–MS) for the concentration, separation and quantitation of non-ionic surfactants has been investigated. Concentration was based on the formation of mixed aggregates of analytes [alkylphenol ethoxylates (APE, octyl and nonyl) and alkyl ethoxylates (AE, C12–C16)] with the anionic surfactant sodium dodecyl

Manuel Cantero; Soledad Rubio; Dolores Pérez-Bendito

2005-01-01

325

Tracing polar benzene- and naphthalenesulfonates in untreated industrial effluents and water treatment works by ion-pair chromatography-fluorescence and electrospray-mass spectrometry  

Microsoft Academic Search

This paper presents a protocol for the determination of a class of polar, ionic and highly water-soluble organic pollutants: benzene- and naphthalenesulfonic acids, compounds widely used in chemical, pharmaceutical, tannery, paper and textile industries. This protocol involves the use of a solid-phase extraction (SPE) followed by ion-pair chromatography-electrospray-mass spectrometry (IPC-ESI-MS). In this work two polymeric solid-phase extraction cartridges (Isolute ENV+

M. C Alonso; D Barceló

1999-01-01

326

Analysis of iodinated X-ray contrast agents in water samples by ion chromatography and inductively-coupled plasma mass spectrometry  

Microsoft Academic Search

In this paper, an analytical method for the determination of six iodinated X-ray contrast agents (amidotrizoic acid, iohexol, iomeprol, iopamidol, iopromide, and ioxitalamic acid), iodide, and iodate in water samples is presented. The method is based on a separation of the analytes by ion chromatography (IC) and a subsequent detection by inductively-coupled plasma mass spectrometry (ICP-MS). The method was optimised

Frank Sacher; Brigitte Raue; Heinz-Jürgen Brauch

2005-01-01

327

Trace analysis of heavy metals in groundwater samples by ion chromatography with post-column reaction and ultraviolet–visible detection  

Microsoft Academic Search

Groundwaters originating from local and regional aquifers surrounding ash deposits produced by a coal-fired power plant were collected. These water samples were chemically analyzed for quantifying their heavy metal composition at trace levels. A highly sensitive analytical technique based on ion chromatography with a UV–Vis detector and under isocratic eluent flow-rate conditions was used. In order to quantify the major

E Santoyo; S Santoyo-Gutiérrez; Surendra P Verma

2000-01-01

328

Use of fluorescent DNA-intercalating dyes in the analysis of DNA via ion-pair reversed-phase denaturing high-performance liquid chromatography  

Microsoft Academic Search

SYBR Green 1 is an asymmetrical cyanine DNA-binding dye that provides an opportunity for increasing the sensitivity of nucleic acid detection when used in conjunction with gel electrophoresis. In this paper, we summarize the general properties and specific uses of SYBR green 1 in ion-pair reversed-phase denaturing high-performance liquid chromatography (IP DHPLC). We describe several applications for the WAVE DHPLC

Ahmad R Bahrami; Mark J Dickman; Maryam M Matin; John R Ashby; Paul E Brown; Matthew J Conroy; Gregory J. S Fowler; James P Rose; Qaiser I Sheikh; Anthony T Yeung; David P Hornby

2002-01-01

329

Comparative Study of Ion Interaction Reagents for the Separation of Lanthanides by Reversed-Phase High Performance Liquid Chromatography (RP-HPLC)  

Microsoft Academic Search

A study of two ion interaction reagents (IIRs) viz. n-octadecane sulphonate (C18-sulphonate) and eicosyl sulphate (C20-sulphate) was carried out for the separation of lanthanides by reversed-phase high performance liquid chromatography (RP–HPLC). The objective of the study was to identify a suitable IIR offering long term adsorption onto the RP column, thereby obviating the need to introduce the IIR in the

P. G. Jaison; Pranaw Kumar; Vijay M. Telmore; Suresh K. Aggarwal

2009-01-01

330

Trace Level Determination of Lewisite in Water by SolidPhase Microextraction and Gas Chromatography-Mass Spectrometry with Selected Ion-Monitoring  

Microsoft Academic Search

A new analytical procedure was developed for the extraction of Lewisite of chemical warfare agents from water and for derivatization prior to analysis by gas chromatography-mass spectrometry (GC-MS) with selected ion-monitoring. Firstly, lewisite and its degradation products 2-chlorovinylarsonous acid (CVAA) or 2-chlorovinylarsenous oxide(CVAO) or 2-chlorovinylarsonic acid (CVAOA) were derivatized with the propane- 1,3-dithiol, then SPME with 100 mum polydimethylsiloxane (PDMS)

Zhou Liming; Zhou Jianmei; Liu Bo; Dong Junjun; Lu Shengli; Lu Caihong

2008-01-01

331

Direct analysis of carbohydrates in animal plasma by ion chromatography coupled with mass spectrometry and pulsed amperometric detection for use as a non-invasive diagnostic tool  

Microsoft Academic Search

The present paper demonstrates that electrochemical detection (ECD) coupled to ion chromatography and electrospray ionization tandem mass spectrometry (IC-ECD–ESI\\/MS\\/MS) can be used to rapidly estimate some indications of the health status of organisms. The lactulose to mannitol ratio (L\\/M) is used as a non-invasive assay to investigate small intestinal absorption pathways and mucosal integrity. In the present study, an evaluation

Darja Kotnik; Andrej Šmidovnik; Petra Jazbec-Križman; Mitja Križman; Mirko Prošek

332

Liquid chromatography-tandem mass spectrometric ion-switching determination of chlorantraniliprole and flubendiamide in fruits and vegetables.  

PubMed

The anthranilic and phthalic diamides, chlorantraniliprole (CAP) and flubendiamide (FLU), respectively, represent a new class of very effective insecticides that activate the ryanodine-sensitive intracellular calcium release channel (ryanodine receptor). This paper reports an analytical method for the simultaneous determination of the two insecticides on fruits and vegetables by liquid chromatography-electrospray tandem mass spectrometry operated in the positive and negative ionization switching mode. The two diamides were extracted with acetonitrile and separated on a Zorbax Column Eclipse XDB C8 (4.6 mm x 150 mm i.d., 3 microm) by isocratic elution with a mobile phase consisting of acetonitrile and water with 0.1% formic acid pumped at a flow rate of 0.4 mL/min. The diamides were selectively detected by multiple reaction monitoring for transitions of proton adduct precursor ions simultaneously: positive m/z 484.3-->285 for CAP, m/z 445.5-->169 for internal standard, and negative m/z 681.4-->253 for FLU. For CAP calibration in the positive mode was linear over a working range of 2 to 1000 microg/L with r > 0.992. The limit of detection (LOD) and limit of quantification (LOQ) for CAP were 0.8 and 1.6 microg/kg, respectively. For FLU in the negative mode the corresponding values were 1-1000 microg/L for linear working range, with r > 0.996 and 0.4 and 0.8 microg/L for LOD and LOQ, respectively. Moreover, the presence of interfering compounds in the fruit and vegetable extracts was found to be minimal. Due to the linear behavior of the MS detector response for the two analytes, it was concluded that the multiple reaction transitions of molecular ions in the ion-switching mode can be used for analytical purposes, that is, for identification and quantification of diamides in fruit and vegetable extracts at trace levels. PMID:18690687

Caboni, Pierluigi; Sarais, Giorgia; Angioni, Alberto; Vargiu, Simona; Pagnozzi, Daniela; Cabras, Paolo; Casida, John E

2008-09-10

333

The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry  

SciTech Connect

The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

Johnson, S.

1999-02-12

334

Molecular weights and gyration radii of amylopectins determined by high-performance size-exclusion chromatography equipped with multi-angle laser-light scattering and refractive index detectors  

Microsoft Academic Search

High-performance size-exclusion chromatography (HPSEC) equipped with multi-angle laser-light scattering (MALLS) and refractive index (RI) detectors was used to determine weight-average molecular weight (Mw) and z-average radius of gyration (Rz) of amylopectin of selected starches. Ranges of Mw and Rz values of amylopectin were 7.0×107–5.7×109g\\/mol and 191–782nm, respectively. Amylopectins of waxy starches had substantially larger Mw than did those of normal

Sang-Ho Yoo; Jay-lin Jane

2002-01-01

335

Studies on microgels: 2. Analysis of the reaction between ‘living’ poly(4-t-butylstyrene) and dimethacrylates by size exclusion chromatography coupled with d.r.i., u.v. and m.a.l.l.s. detectors  

Microsoft Academic Search

The reaction between ‘living’ poly(4-t-butylstyrene) [P(tBS)], and the dimethacrylates ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (BDDMA) was analysed by size exclusion chromatography equipped with a differential refractive index (d.r.i.), an ultraviolet (u.v.) and a light scattering detector (l.s.). The information obtained by the d.r.i. and u.v. detectors allowed the calculation of the concentration of 4-t-burylstyrene and dimethacrylate along the

Ludger Pille; Akhil G. Jhingran; Evamarie P. Capareda; David H. Solomon

1996-01-01

336

Development and validation of an ion-exchange chromatography method for heparin and its impurities in heparin products.  

PubMed

An anion-exchange liquid chromatography method for the determination of heparin and its impurities (dermatan sulfate and oversulfated chondroitin sulfate) was developed using chemometric-assisted optimization, including multivariate experimental design and response surface methodology. The separation of heparin, dermatan sulfate, and oversulfated chondroitin sulfate (Rs above 2.0) was achieved on a Dionex RF IC IonPac AS22 column with a gradient elution of 10-70% of 2.5 M sodium chloride and 20 mM Tris phosphate buffer (pH 2.1) at a flow rate of 0.6 mL/min and UV detection at 215 nm. Method validation shows good linearity (r > 0.99), acceptable precision (%relative standard deviations <11.4%) and trueness (%recovery of 92.3-103.9%) for all analytes. The limits of detection for dermatan sulfate and oversulfated chondroitin sulfate are equivalent to 0.11% w/w (10.5 ?g/mL) and 0.07% w/w (7.2 ?g/mL), while the limits of quantification are 0.32% w/w (31.5 ?g/mL) and 0.22% w/w (22.0 ?g/mL) relative to heparin, respectively. The method is specific for heparin, dermatan sulfate, and oversulfated chondroitin sulfate without interference from mobile phase and sample matrices and could be used for accurate quantitation the drug and its impurities in a single run. Applications of the method reveal contents of heparin between 90.3 and 97.8%. Dermatan sulfate and oversulfated chondroitin sulfate were not detected in any of the real-life samples. PMID:25146711

Thiangthum, Sumate; Heyden, Yvan Vander; Buchberger, Wolfgang; Viaene, Johan; Prutthiwanasan, Brompoj; Suntornsuk, Leena

2014-11-01

337

Analysis of 19-nortestosterone residue in animal tissues by ion-trap gas chromatography-tandem mass spectrometry*  

PubMed Central

A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with ?-glucuronidase from Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol/L). Next, the homogenate was mixed with methanol and heated at 60 °C for 15 min, then placed in an ice-bath at ?18 °C for 2 h. After liquid-liquid extraction with n-hexane, the analytes were subjected to a normal-phase solid phase extraction (SPE) C18 cartridge for clean-up. The dried organic extracts were derivatized with heptafluorobutyric anhydride (HFBA), and then the products were injected into GC-MS. Using electron impact mass spectrometry (EI-MS) with positive chemical ionization (PCI), four diagnostic ions (m/z 666, 453, 318, and 306) were determined. A standard calibration curve over the concentration range of 1–20 ng/g was reached, with Y=467 084X?68 354 (R 2=0.999 7) for 19-NT, and the detection limit was 0.3 ng. When applied to spiked samples collected from bovine and ovine, the recoveries ranged from 63% to 101% with relative standard deviation (RSD) between 2.7% and 8.9%. The procedure is a highly efficient, sensitive, and more economical method which offers considerable potential to resolve cases of suspected nandrolone doping in husbandry animals. PMID:21634039

Jiang, Jin-qing; Zhang, Lei; Li, Guang-ling; Zhang, Hai-tang; Yang, Xue-feng; Liu, Jun-wei; Li, Ren-feng; Wang, Zi-liang; Wang, Jian-hua

2011-01-01

338

Chemometric Analysis of Gas Chromatography – Mass Spectrometry Data using Fast Retention Time Alignment via a Total Ion Current Shift Function  

SciTech Connect

A critical comparison of methods for correcting severely retention time shifted gas chromatography-mass spectrometry (GC-MS) data is presented. The method reported herein is an adaptation to the Piecewise Alignment Algorithm to quickly align severely shifted one-dimensional (1D) total ion current (TIC) data, then applying these shifts to broadly align all mass channels throughout the separation, referred to as a TIC shift function (SF). The maximum shift varied from (-) 5 s in the beginning of the chromatographic separation to (+) 20 s toward the end of the separation, equivalent to a maximum shift of over 5 peak widths. Implementing the TIC shift function (TIC SF) prior to Fisher Ratio (F-Ratio) feature selection and then principal component analysis (PCA) was found to be a viable approach to classify complex chromatograms, that in this study were obtained from GC-MS separations of three gasoline samples serving as complex test mixtures, referred to as types C, M and S. The reported alignment algorithm via the TIC SF approach corrects for large dynamic shifting in the data as well as subtle peak-to-peak shifts. The benefits of the overall TIC SF alignment and feature selection approach were quantified using the degree-of-class separation (DCS) metric of the PCA scores plots using the type C and M samples, since they were the most similar, and thus the most challenging samples to properly classify. The DCS values showed an increase from an initial value of essentially zero for the unaligned GC-TIC data to a value of 7.9 following alignment; however, the DCS was unchanged by feature selection using F-Ratios for the GC-TIC data. The full mass spectral data provided an increase to a final DCS of 13.7 after alignment and two-dimensional (2D) F-Ratio feature selection.

Nadeau, Jeremy S.; Wright, Bob W.; Synovec, Robert E.

2010-04-15

339

Analysis of Acid Gas Emissions in the Combustion of the Binder Enhanced D-Rdf by Ion Chromatography.  

NASA Astrophysics Data System (ADS)

Waste-to-energy has become an attractive alternative to landfills. One concern in this development is the release of pollutants in the combustion process. The binder enhanced d-RDF pellets satisfy the requirements of environmental acceptance, chemical/biological stability, and being storeable. The acid gas emissions of combusting d-RDF pellets with sulfur -rich coal were analyzed by ion chromatography and decreased when d-RDF pellets were utilized. The results imply the possibility of using d-RDF pellets to substitute for sulfur -rich coal as fuel, and also substantiate the effectiveness of a binder, calcium hydroxide, in decreasing emissions of SOx. In order to perform the analysis of the combustion sample, sampling and sample pretreatment methods prior to the IC analysis and the first derivative detection mode in IC are investigated as well. At least two trapping reagents are necessary for collecting acid gases: one for hydrogen halides, and the other for NOx and SOx. Factors affecting the absorption of acid gases are studied, and the strength of an oxidizing agent is the main factor affecting the collection of NOx and SOx. The absorption preference series of acid gases are determined and the absorption models of acid gases in trapping reagents are derived from the analytical results. To prevent the back-flushing of trapping reagents between impingers when leak-checking, a design for the sampling train is suggested, which can be adopted in sample collections. Several reducing agents are studied for pretreating the sample collected in alkali -permanganate media. Besides the recommendation of the hydrogen peroxide solution in EPA method, methanol and formic acid are worth considering as alternate reducing agents in the pretreatment of alkaline-permanganate media prior to IC analysis. The first derivative conductivity detection mode is developed and used in IC system. It is efficient for the detection and quantification of overlapping peaks as well as being applicable for nonoverlapping peaks.

Jen, Jen-Fon

1988-12-01

340

Identification and Quantification of Glycoproteins Using Ion-Pairing Normal-phase Liquid Chromatography and Mass Spectrometry*  

PubMed Central

Glycoprotein structure determination and quantification by MS requires efficient isolation of glycopeptides from a proteolytic digest of complex protein mixtures. Here we describe that the use of acids as ion-pairing reagents in normal-phase chromatography (IP-NPLC) considerably increases the hydrophobicity differences between non-glycopeptides and glycopeptides, thereby resulting in the reproducible isolation of N-linked high mannose type and sialylated glycopeptides from the tryptic digest of a ribonuclease B and fetuin mixture. The elution order of non-glycopeptides relative to glycopeptides in IP-NPLC is predictable by their hydrophobicity values calculated using the Wimley-White water/octanol hydrophobicity scale. O-linked glycopeptides can be efficiently isolated from fetuin tryptic digests using IP-NPLC when N-glycans are first removed with PNGase. IP-NPLC recovers close to 100% of bacterial N-linked glycopeptides modified with non-sialylated heptasaccharides from tryptic digests of periplasmic protein extracts from Campylobacter jejuni 11168 and its pglD mutant. Label-free nano-flow reversed-phase LC-MS is used for quantification of differentially expressed glycopeptides from the C. jejuni wild-type and pglD mutant followed by identification of these glycoproteins using multiple stage tandem MS. This method further confirms the acetyltransferase activity of PglD and demonstrates for the first time that heptasaccharides containing monoacetylated bacillosamine are transferred to proteins in both the wild-type and mutant strains. We believe that IP-NPLC will be a useful tool for quantitative glycoproteomics. PMID:19525481

Ding, Wen; Nothaft, Harald; Szymanski, Christine M.; Kelly, John

2009-01-01

341

High-pressure liquid chromatography of amino acids, peptides and proteins. V. Separation of thyroidal iodo-amino acids by hydrophilic ion-paired reversed-phase high-performance liquid chromatography.  

PubMed

The separation of thyroidal iodoamino acids has been carried out by high-performance liquid chromatography in phase systems consisting of chemically bonded C18-hydrophobic supports as the stationary phase and water-organic solvent mixtures containing phosphoric acid or other ion-pairing reagents as the mobile phase. Under conditions of hydrophilic ion-pair formation, excellent resolution of the iodoamino acids is observed. This method permits the rapid separation and, hence, analysis of mixtures containing thyroxine, 3,3',5-triiodothyronine and 3,3',5'-triiodothyronine and related compounds in ca. 30 min with sensitivity, using a UV monitor at 210 nm, at the 1-10-pmole level. PMID:701445

Hearn, M T; Hancock, W S; Bishop, C A

1978-09-21

342

Determination of fluorescent whitening agents in laundry detergents and surface waters by solid-phase extraction and ion-pair high-performance liquid chromatography.  

PubMed

A simple method was developed to detect four stilbene-type disulfonate and one distyrylbiphenyl-type fluorescent whitening agents (FWAs) in household laundry detergents and surface waters by ion-pair high-performance liquid chromatography. The FWA concentrations in detergents were measured directly. The contents of FWAs in water samples were extracted by solid-phase extraction (C18-SPE) with ion-pairing reagent, and were then determined by an isocratic ion-pair chromatography (IPC) using a C18 column, applying tetrabutylammonium hydrogensulfate (TBA) as the ion-pairing reagent in mobile phase, and equipped with fluorescence detection. Water samples at various pH conditions for SPE were evaluated. Experimental results indicate that the proposed method is precise and sensitive in analyzing FWAs, and enables quantitation of 0.01-0.1 microg/l in 100 ml water samples. The recovery rates of FWAs in spiked water samples were between 73 and 89%, and the precision (RSD) ranged from 2.6 to 8.9%. Over 7200 microg/g of 4,4'-bis(2-sulfostryl)-biphenyl (DSBP) and 2320 microg/g of 4,4'-bis[(4-anilino-6-morpholino-1,3,5-triazine-2-yl)-amino]stilbene-2,2'-disulfonate (DAS1) were detected in household laundry detergents. Trace amounts of DSBP were detected in surface water samples ranging from 0.2 to 3.7 microg/l. PMID:16130754

Shu, Wei-Chuan; Ding, Wang-Hsien

2005-09-23

343

Exclusive processes in electron-ion collisions in the dipole formalism  

SciTech Connect

We compare the predictions of two saturation models for production of vector mesons and of photons in electron-ion collisions. The models considered are the b-CGC and the rcBK. The calculations were made in the kinematical range of the LHeC and of the future eRHIC.

Cazaroto, E. R.; Navarra, F. S. [Instituto de Fisica, Universidade de Sao Paulo, C.P. 66318, 05314-970 Sao Paulo, SP (Brazil); Carvalho, F. [Departamento de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo, Campus Diadema, Rua Prof. Artur Riedel, 275, Jd. Eldorado, 09972-270 Diadema, SP (Brazil); Goncalves, V. P. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900 Pelotas, RS (Brazil)

2013-03-25

344

[A rapid separation and quantitation of sodium cyclamate in food by ion-pair reversed-phase high performance liquid chromatography].  

PubMed

A method of separation and quantitation of sodium cyclamate in foods by ion-pair reversed-phase high performance liquid chromatography is described. Sodium cyclamate can be separated on ODS column at room temperature by using a mobile phase of V(methanol):V(water, containing ion-pair reagent) = 30:70 at 1 mL/min flow rate. The effects of ion-pair reagent and methanol on the retention of sodium cyclamate were studied. The samples were quantified with an ultraviolet detector operated at 205 nm. The calibration curve was linear in the range of 0.50-2.50 g/L with a correlation coefficient of 0.9996. The recoveries were 96.9%-101.7%. The detection limit was 0.05 g/L. This method is simple, rapid and sensitive. PMID:12549127

Li, Z; Yin, Y

1999-05-01

345

Biomonitoring of Aristolactam-DNA Adducts in Human Tissues using Ultra-Performance Liquid Chromatography/Ion-Trap Mass Spectrometry  

PubMed Central

Aristolochic acids (AAs) are a structurally-related family of nephrotoxic and carcinogenic nitrophenanthrene compounds found in Aristolochia herbaceous plants, many of which have been used worldwide for medicinal purposes. AAs have been implicated in the etiology of so-called Chinese herbs nephropathy and of Balkan endemic nephropathy. Both of these disease syndromes are associated with carcinomas of the upper urinary tract (UUC). 8-Methoxy-6-nitrophenanthro-[3,4-d]-1,3-dioxolo-5-carboxylic acid (AA-I) is a principal component of Aristolochia herbs. Following metabolic activation, AA-I reacts with DNA to form aristolactam (AL-I)-DNA adducts. We have developed a sensitive analytical method, using ultra-performance liquid chromatography-electrospray ionization/multistage mass spectrometry (UPLC-ESI/MSn) with a linear quadrupole ion-trap mass spectrometer, to measure 7-(deoxyadenosin-N6-yl) aristolactam I (dA-AL-I) and 7-(deoxyguanosin-N2-yl) aristolactam I (dG-AL-I) adducts. Using 10 ?g of DNA for measurements, the lower limits of quantitation of dA-AL-I and dG-AL-I are, respectively, 0.3 and 1.0 adducts per 108 DNA bases. We have used UPLC-ESI/MSn to quantify AL-DNA adducts in tissues of rodents exposed to AA, and in the renal cortex of patients with UUC who reside in Taiwan, where the incidence of this uncommon cancer is the highest reported for any country in the world. In human tissues, dA-AL-I was detected at levels ranging from 9 to 338 adducts per 108 DNA bases, whereas dG-AL-I was not found. We conclude that UPLC-ESI/MSn is a highly sensitive, specific and robust analytical method, positioned to supplant 32P-postlabeling techniques currently used for biomonitoring of DNA adducts in human tissues. Importantly, UPLC-ESI/MSn could be used to document exposure to AA, the toxicant responsible for AA nephropathy and its associated UUC. PMID:22515372

Yun, Byeong Hwa; Rosenquist, Thomas; Sidorenko, Viktoriya; Iden, Charles; Chung-Hsin, Chen; Pu, Yeong-Shiau; Bonala, Radha; Johnson, Francis; Dickman, Kathleen G.; Grollman, Arthur P.; Turesky, Robert J.

2012-01-01

346

Field detection of bacillus spore aerosols with stand-alone pyrolysis-gas chromatography and ion mobility spectrometry  

NASA Astrophysics Data System (ADS)

A commercially available, hand-held chemical vapor detector was modified to detect Gram-positive Bacillus subtilis var. globigii spores (BG) in outdoor field scenarios. An Airborne Vapor Monitor (AVM) ion mobility spectrometry (IMS) vapor detector was interfaced to a biological sample processing and transfer introduction system. The biological sample processing was accomplished by quartz tube pyrolysis (Py), and the resultant vapor was transferred by gas chromatography (GC) to the IMS detector. The Py-GC/IMS system can be described as a hyphenated device where two analytical dimensions, in series, allow the separation and isolation of individual components from the pyrolytic decomposition of biological analytes. Gram positive spores such as BG contain 5 - 15% by weight of dipicolinic acid (DPA), and picolinic acid is a pyrolysis product of DPA. Picolinic acid has a high proton affinity, and it is detected in a sensitive fashion by the atmospheric pressure-based IMS device. Picolinic acid occupies a unique region in the GC/IMS data domain with respect to other bacterial pyrolysis products. A 1000 to 1, air-to-air, aerosol concentrator was interfaced to the Py-GC/IMS instrument, and the system was placed in an open-air, Western United States desert environment. The system was tested with BG spore aerosol releases, and the instrument was remotely operated during a trial. A Met-One aerosol particle counter was placed next to the Py-GC/IMS so as to obtain a real-time record of the ambient and bacterial aerosol challenges. The presence/absence of an aerosol event, determined by an aerosol particle counter and a slit sampler-agar plate system, was compared to the presence/absence of a picolinic acid response in a GC/IMS data window at selected times in a trial with respect to a BG challenge. In the 21 BG trials, the Py-GC/IMS instrument experienced two true negatives, no false positives, and the instrument developed a software failure in one trial. The remaining 18 trials were true positive determinations for the presence of BG aerosol, and a limit of detection for the Py-GC/IMS instrument was estimated at approximately 3300 BG spore-containing particles.

Snyder, A.; Maswadeh, Waleed M.; Parsons, John A.; Tripathi, Ashish; Meuzelaar, Henk L. C.; Dworzanski, Jacek P.; Kim, Man-Goo

1999-12-01

347

[Simultaneous determination of residues of six imidazolinone herbicides in adzuki beans by high performance liquid chromatography-electrospray ion trap tandem mass spectrometry].  

PubMed

A method for the simultaneous determination of six pesticides in adzuki beans by high performance liquid chromatography-electrospray ion trap tandem mass spectrometry was developed and evaluated. The sample was extracted with 0.1 mol/L NH4HCO3 (pH 5)-methanol (70 : 30, v/v). The extract was partitioned with dichloromethane, and cleaned up with gel permeation chromatography. The separation was performed on an Inertsil ODS-3 column (150 mm x 2.1 mm, 5 microm) with the gradient elution of methanol and 1% acetic acid as mobile phase. The identification and quantification were performed by electrospray ion trap mass spectrometry with selected ion monitoring mode. The calibration curves of imidazolinone herbicides showed good linearities in the range of 10 - 200 microg/L (5 -100 microg/L for imazaquin) with the correlation coefficients between 0.998 7 and 0.999 7. The limits of detection ranged between 0.2 microg/kg and 0.5 microg/kg (S/N = 3). The average recoveries of six imidazolinone herbicides spiked in adzuki beans ranged between 81.6% and 99.4% (n = 6) with the relative standard deviations of 3.1% -7.8%. The method has been used for the determination of 6 imidazolinone herbicides simultaneously in adzuki beans with easy operation, high accuracy and good precision. PMID:19253552

Li, Cheng; Suo, Ran; Wang, Fengchi; Ma, Hongying

2008-11-01

348

Investigation of isomeric flavanol structures in black tea thearubigins using ultraperformance liquid chromatography coupled to hybrid quadrupole/ion mobility/time of flight mass spectrometry.  

PubMed

Ultra performance liquid chromatography (UPLC) when coupled to ion mobility (IMS)/orthogonal acceleration time of flight mass spectrometry is a suitable technique for analyzing complex mixtures such as the black tea thearubigins. With the aid of this advanced instrumental analysis, we were able to separate and identify different isomeric components in the complex mixture which could previously not be differentiated by a conventional high performance liquid chromatography/tandem mass spectrometry. In this study, the difference between isomeric structures theasinensins, proanthocyanidins B-type and rutin (quercetin-3O-rutinoside) were studied, and these are present abundantly in many botanical sources. The differentiation between these structures was accomplished according to their acquired mobility drift times differing from the traditional investigations in mass spectrometry, where calculation of theoretical collisional cross sections allowed assignment of the individual isomeric structures. The present work demonstrates UPLC-IMS-MS as an efficient technology for isolating and separating isobaric and isomeric structures existing in complex mixtures discriminating between them according to their characteristic fragment ions and mobility drift times. Therefore, a rational assignment of isomeric structures in many phenolic secondary metabolites based on the ion mobility data might be useful in mass spectrometry-based structure analysis in the future. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25395124

Yassin, Ghada H; Grun, Christian; Koek, Jean H; Assaf, Khaleel I; Kuhnert, Nikolai

2014-11-01

349

Analysis of excitation functions from light ion induced reactions in the EXCLUSIVE INDEX model  

NASA Astrophysics Data System (ADS)

The previously introduced EXCLUSIVE INDEX model allows to predict the population of 6 residual nuclei including the primary compound nucleus through two stages of the preequilibrium phase. The present version is limited to maximum two-nucleon emission. The preequilibrium ejectiles may reduce the brought-in rotational energy by a model of maximum angular momentum decoupling. Subsequent evaporation of protons, neutrons and ?-particles is treated in the frame of the Weisskopf-Ewing and s-wave approximation considering pairing effects only in compound nucleus state densities. The sensitivity of essential preequilibrium parameters on the shape of calculated excitation functions is tested. The model predictions well compare to excitation functions from p, d,3He and4He induced reactions including the large set from the reaction93Nb(4He, xn yp) up to 170 MeV bombarding energy. The general importance of two-nucleon preequilibrium emission is accentuated in several examples. The deduced preequilibrium parameters corroborate the results from the INDEX model analysis of nucleon spectra.

Ernst, J.; Friedland, W.; Stockhorst, H.

1989-03-01

350

Purification of malted-barley endo-beta-D-glucanases by ion-exchange chromatography: some properties of an endo-barley-beta-D-glucanase.  

PubMed

Two endo-beta-D-glucanases which act, respectively, on (1 leads to 3)-beta-D-glucans and barley beta-D-glucan have been isolated from malted barley, and purified by ion-exchange chromatography. The latter enzyme is highly specific for barley beta-D-glucan, and has no action on either (1 leads to 3)- or (1 leads to 4)-beta-D-glucans. It will also act on dyed barley-beta-D-glucan. Certain group-specific reagents inhibit the endo-barley-beta-D-glucanase and the endo-(1 leads to 3)-beta-D-glucanase to similar extents. PMID:947540

Manners, D J; Wilson, G

1976-06-01

351

Use of 1-(2-pyridylazo)-2-naphthol as the post column reagent for ion exchange chromatography of heavy metals in environmental samples  

Microsoft Academic Search

Ion exchange chromatography (IEC) using a bi-functional column (quaternary ammonium and sulfonate groups), followed by post-column reaction (PCR) with 1-(2-pyridylazo)-2-naphthol (PAN), was used to separate and quantitate Cu(II), Ni(II), Zn(II), Co(II), Cd(II), Mn(II) and Hg(II) at low concentration levels. IEC–PCR separation was achieved within 14min using the mobile phase containing 3mmolL?1 2,6-pyridinedicarboxylic acid (PDCA) and 3mmolL?1 oxalate at pH 12.5.

Supalax Srijaranai; Wijitra Autsawaputtanakul; Yanawath Santaladchaiyakit; Tipwan Khameng; Archava Siriraks; Richard L. Deming

2011-01-01

352

Chelation ion chromatography of alkaline earth and transition metals a using monolithic silica column with bonded N-hydroxyethyliminodiacetic acid functional groups.  

PubMed

A commercially available porous silica monolithic column (Onyx Monolithic Si, 100 mm×4.6 mm I.D.) was 'in-column' covalently functionalised with 2-hydroxyethyliminodiacetic acid (HEIDA) groups, and applied to the simultaneous and rapid separation of alkaline earth and transition metal ions, using high-performance chelation ion chromatography (HPCIC). With a 0.3mM dipicolinic acid (DPA) containing eluent, the baseline separation of various common transition and heavy metal ions and the four alkaline earth metal ions could be achieved in under 14 min with a flow rate of just 0.8 mL/min. Detection was achieved using spectrophotometric detection at 540 nm after post-column reaction (PCR) with 4-(2-pyridylazo)-resorcinol (PAR). Significant effects from variation of eluent nature, concentration and temperature upon selectivity and retention were demonstrated with the new monolithic silica chelating phase. Under optimised conditions (0.165 M LiNO(3) eluent, pH 2.5), peak efficiencies of 54,000, 60,000 and 64,000 N/m, for Zn(2+), Mn(2+) and Cd(2+), respectively, were recorded, far exceeding that previously reported for IDA based chelation ion exchange columns. PMID:23298846

McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Jones, Phil; Paull, Brett

2013-02-01

353

Comprehensive impurity profiling of nutritional infusion solutions by multidimensional off-line reversed-phase liquid chromatography × hydrophilic interaction chromatography-ion trap mass-spectrometry and charged aerosol detection with universal calibration.  

PubMed

A new analysis strategy was employed for the establishment of a comprehensive qualitative and quantitative impurity profile of a stressed multi-constituent pharmaceutical drug formulation, namely a nutritional infusion solution composed of amino acids and dipeptides. To deal with the highly complex samples a multidimensional analysis approach was developed which made use of an off-line two-dimensional reversed-phase liquid chromatography (RPLC)×hydrophilic interaction chromatography (HILIC) separation and combination of complementary detection involving ion trap mass spectrometry (IT-MS) and a charged aerosol detector (CAD). The CAD is a mass-sensitive universal detector for non-volatile compounds with relatively consistent detector response. A universal calibration function was set up with a set of standards. This universal calibration function was then employed to quantify unknown impurities allowing their classification into those that need to be reported (>0.05% relative to the precursor compound), identified (>0.1%), and quantified (>0.15%). The dilemma of unavailability of authentic standards at this stage of research for quantification could thereby be circumvented. Relevant impurities above the reporting threshold were identified by IT-MS. Impurities detected comprised di-, tri- and tetrapeptides, cyclic dipeptides (diketopiperazines), pyroglutamic acid derivatives and their condensation products. Cross-validation with HPLC-MS/MS methods using synthesized authentic standards confirmed the results obtained by the presented multidimensional analysis assay. PMID:22284534

Schiesel, Simone; Lämmerhofer, Michael; Lindner, Wolfgang

2012-10-12

354

Static headspace-multicapillary column with gas chromatography coupled to ion mobility spectrometry as a simple approach for the discrimination of crude and processed traditional Chinese medicines.  

PubMed

The processing procedure can alter the nature and chemical transformation of traditional Chinese medicine to accommodate different clinical dispensing and preparation requirements. In this study, static headspace-multicapillary column with gas chromatography coupled to ion mobility spectrometry was developed for the rapid and sensitive discrimination of crude and processed traditional Chinese medicine. Using Radix Paeoniae Alba as a traditional Chinese medicine model, the combined power of this approach was illustrated by classifying the crude and processed Radix Paeoniae Alba samples into two main categories. The contents of the main components in Radix Paeoniae Alba varied significantly. The established method could promote the use of ion mobility spectrometry in intrinsic quality control and differentiation of herbal medicines from other processed products or preparations. PMID:25113615

Cao, Gang; Shou, Qiyang; Li, Qinglin; Jiang, Jianping; Chen, Xiaocheng

2014-11-01

355

Characteristic fragmentation patterns of the trimethylsilyl and trimethylsilyl-oxime derivatives of various saccharides as obtained by gas chromatography coupled to ion-trap mass spectrometry.  

PubMed

The fragmentation patterns of selected glycosidic linkage containing non-reducing (methylmannoside, methylgalactoside, lactitol, sucrose, trehalose, raffinose, erlose, melezitose) and reducing saccharides (maltose, cellobiose, lactose, melibiose, palatinose, primeverose, rutinose) have been compared as their trimethylsilyl and as their trimethylsilyl-oxime derivatives. Fragmentation characteristics of the glycosidic linkage containing trimethylsilyl-oxime derivatives have been investigated at the first time: these spectra are not available in the official libraries (NIST, Wiley). Applying gas chromatography-ion trap mass spectrometry, informative fragments of high masses with high intensities have been obtained. Results confirmed characteristic differences between the simple trimethylsilyl derivative providing non-reducing glycosides and the trimethylsilyl, syn and antioxime species. Fragmentation starts at the glycosidic linkage resulting in the case of the non-reducing di- and trisaccharides in two, identical fragments of ring structure, with the abundant selective fragment ion at m/z=361. In the case of reducing disaccharides fragmentation provides two different moieties: one moiety of ring structure at m/z=361, and one of the open chain trimethylsilyl-oxime moiety with two special fragment ions at m/z=361 and at m/z=538. These fragmentation patterns proved to be independent on the position of the glycosidic linkage. Distribution of the selective fragment ions, obtained from their total ion current elutions, was evaluated on a quantitative basis, expressed in percentages of the total of ions formed. Reproducibility in the formation of these selective fragment ions, depending on their amount to be fragmented, proved to be proper for identification and quantitation purposes, equally. On this basis, in addition to the authentic ones, also two reducing disaccharides (primeverose and rutinose), as authentic compounds not available on the market, were identified and quantified in natural matrices. PMID:18061601

Füzfai, Zs; Boldizsár, I; Molnár-Perl, I

2008-01-01

356

HPLC Analysis of Amino Acids with Ion Exchange Chromatography and O-Phthalaldehyde Post-Column Derivatization: Applications to the Assay of Endogenous Free Amino Acids and Their Transport in Human Placental Villus  

Microsoft Academic Search

A method using high performance liquid chromatography (HPLC) for the analysis of primary amino acids in human placenta is described. This method involves separation of primary amino acids by high performance ion-exchange chromatography followed by post column derivatization using O-phlthalaldehyde (OPA) and 2-mercaptoethanol and fluorescence (excitation 340 nm and emission 410 nm) detection of derivatives. Waters 840 HPLC Amino Acid

B. V. Rama Sastry; V. E. Janson; M. Horst; C. C. Stephan

1986-01-01

357

Evaluation of IDA-PEVA hollow fiber membrane metal ion affinity chromatography for purification of a histidine-tagged human proinsulin.  

PubMed

Inabilities to process particulate material and to allow the use of high flow rates are limitations of conventional chromatography. Membranes have been suggested as matrix for affinity separation due to advantages such as allowing high flow rates and low-pressure drops. This work evaluated the feasibility of using an iminodiacetic acid linked poly(ethylenevinyl alcohol) membrane in the immobilized metal ion affinity chromatography (IMAC) purification of a human proinsulin(His)(6) of an industrial insulin production process. The screening of metal ions showed Ni(2+) as metal with higher selectivity and capacity among the Cu(2+), Ni(2+), Zn(2+) and Co(2+). The membrane showed to be equivalent to conventional chelating beads in terms of selectivity and had a lower capacity (3.68 mg/g versus 12.26 mg/g). The dynamic adsorption capacity for human proinsulin(His)(6) was unaffected by the mode of operation (dead-end and cross-flow filtration). PMID:16531127

de Aquino, Luciana Cristina Lins; de Sousa, Heloisa Ribeiro Tunes; Miranda, Everson Alves; Vilela, Luciano; Bueno, Sônia Maria Alves

2006-04-13

358

An optimized method for the determination of perfluorooctanoic acid, perfluorooctane sulfonate and other perfluorochemicals in different matrices using liquid chromatography/ion-trap mass spectrometry.  

PubMed

Perfluorochemicals (PFC's) are widely spread in the environment and have been detected in blood of wildlife and humans world-wide. Recently, various toxic effects of PFC's in laboratory rats have been demonstrated, resulting in increased government concerns regarding the presence of PFC's in the environment and the implications they have on human health. In the last decade, various analytical methods have been developed for the analysis of PFC's in different matrices whereby the majority of methods have utilised liquid chromatography coupled with mass spectrometry (LC-MS). Here we describe an optimized method for the quantitation of PFC's, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), in food packaging, polytetrafluoroethylene (PTFE) sealant tape and drinking water. The method involved PFC's extraction via off-line SPE followed by separation using reversed-phase liquid chromatography on a Phenyl-Hexyl column coupled with ion-trap (IT) mass spectrometric detection. The optimized approach minimized ion-suppression effects commonly seen with conventional elution buffers, improving detection limits down to 25 pg/mL and allowed effective quantitation down to 50 pg/mL for PFOA and PFOS. The optimized LC-MS method detected PFOA and other PFC's in microwave popcorn packaging and PFOA in PTFE sealant tape in the low ?g/kg. In all samples, PFOS was not detected. PMID:21700512

Dolman, Sebastiaan; Pelzing, Matthias

2011-07-15

359

Analysis of Highly Polar Compounds of Plant Origin: Combination of Hydrophilic Interaction Chromatography and Electrospray Ion Trap Mass Spectrometry  

Microsoft Academic Search

The primary goal of metabolomic analysis is the unbiased relative quantification of every metabolite in a biological system. A number of different metabolite-profiling techniques must be combined to make this possible. Here we report the separation and analysis of highly polar compounds in a proof of concept study. Compounds were separated and analyzed using hydrophilic interaction liquid chromatography (HILIC) coupled

Vladimir V. Tolstikov; Oliver Fiehn

2002-01-01

360

Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring  

ERIC Educational Resources Information Center

Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining…

Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

2005-01-01

361

Ion-exclusion chromatographic separations of C1-C6 aliphatic carboxylic acids on a sulfonated styrene-divinylbenzene co-polymer resin column with 5-methylhexanoic acid as eluent.  

PubMed

The application of C7 aliphatic carboxylic acids (heptanoic, 2-methylhexanoic, 5-methylhexanoic and 2,2-dimethyl-n-valeric acids) as eluents in ion-exclusion chromatography with conductimetric detection for C1-C6 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic and caproic acids) was carried out using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as a stationary phase. When using 0.05 mM sulfuric acid at pH 4.0 as the eluent, peak shapes of hydrophobic carboxylic acids (isovaleric, valeric, isocaproic and caproic acids) were tailed strongly. In contrast, when using 1 mM these C7 carboxylic acids at pH ca. 4 as the eluents, although system peaks (vacant peaks) corresponding to these C7 carboxylic acids appeared, peak shapes of these hydrophobic acids were improved drastically. Excellent simultaneous separation and relatively high sensitive conductimetric detection for these C1-C6 aliphatic carboxylic acids were achieved in 25 min on the TSKgel SCX column (150 x 6 mm I.D.) using 1 mM 5-methylhexanoic acid at pH 4.0 as the eluent. PMID:12830882

Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

2003-05-16

362

Determination of lipoic acid, Trolox methyl ether and tocopherols in human plasma by liquid-chromatography and ion-trap tandem mass spectrometry.  

PubMed

A method for the simultaneous determination of lipoic acid and/or Trolox methyl ether, along with ?-, ?- and ?-tocopherol was developed using liquid chromatography-tandem mass spectrometry with negative electrospray ionization (HPLC-ESI-MS/MS) in an ion-trap mass spectrometer. Detection and quantification were accomplished by a multiple reaction monitoring method, using specific transitions from precursor ion to product ion for each analyte. Chromatographic separation was achieved in a 12?min run using a C(18) -bonded phase and methanol-aqueous ammonium acetate elution gradient. Linear correlations of the chromatographic peak area (r.u. × s(-1) ) to the injected amount (ng) gave the slope values (r.u. × s(-1) ?×?ng(-1) ) 2.34?×?10(4) for ?-tocopherol, 5.05?×?10(4) for ?-tocopherol, 1.27?×?10(5) for ?-tocopherol, 8.86?×?10(5) for lipoic acid and 1.23?×?10(5) for Trolox methyl ether. The lower limit of quantification ranged between 0.02 and 1.22?ng for Trolox methyl ether and lipoic acid. MS(3) experiments of ?- and ?-tocopherol suggest ion-radical reactions and dependence of the tocopherol fragmentation pattern on the phenolic ring methylation degree. The method is shown to be applicable to measurement of these metabolites in human serum after extraction. PMID:22222855

Montero, Olimpio; Ramírez, María; Sánchez-Guijo, Alberto; González, Constancio

2012-10-01

363

Journal of Chromatography A, 1043 (2004) 249254 Arsenic complexes in the arsenic hyperaccumulator  

E-print Network

Journal of Chromatography A, 1043 (2004) 249­254 Arsenic complexes in the arsenic hyperaccumulator-exchange chromatography­hydride generation­atomic fluorescence spectroscopy and size-exclusion chromatographyIII-tris-thiolate complexes through thiolate bonds by us- ing size-exclusion chromatography (SEC) or electrospray ionization

Ma, Lena

364

The Preparation of Apo-Cu,Zn Superoxide Dismutase by Ion-Exchange Chromatography on Iminodiacetic Acid–Sepharose  

Microsoft Academic Search

The superoxide dismutases (EC 1.15.1.1) are a family of enzymes that catalyze the dismutation of superoxide radical anion to dioxygen and hydrogen peroxide. The active site contains a critical metal ion such as manganese, iron, or copper. The copper-containing protein also has one zinc ion bound per subunit. The standard method used to remove the metal ions from Cu,Zn superoxide

Barbara Sutter; Patricia L. Bounds; Willem H. Koppenol

2000-01-01

365

Effect of humic acid on absorption-release processes in the bottom sediments-Yenisei river water system as studied by dual-column ion chromatography and ?-ray spectrometry  

Microsoft Academic Search

The effect of humic acid on absorption-release processes in the bottom sediments-Yenisei river water system was studied by\\u000a dual-column ion chromatography and ?-ray spectrometry. With the use of ion chromatography, it was found that processes related\\u000a to the absorption of SO\\u000a 4\\u000a 2?\\u000a and Cl? anions by a solid phase with the release of NO\\u000a 3\\u000a ?\\u000a , PO\\u000a 4

L. G. Bondareva; O. P. Kalyakina; A. Ya. Bolsunovskii

2006-01-01

366

Applying Chromatography.  

ERIC Educational Resources Information Center

Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

Klein, Jessie W.; Patev, Paul

1998-01-01

367

Chromatography Nomenclature and Definitions  

NSDL National Science Digital Library

This website gives the International Union of Pure and Applied Chemistry approved definitions in the field of chromatography. It is critical for students to appreciate the importance of using standardized nomenclature and definitions. Sections of the site include general terminology, terms related to the chromatographic system, terms related to the chromatographic process and the theory of chromatography, terms related to detection, ion exchange, liquid-liquid distribution (solvent extraction) and other related subjects.

2011-05-12

368

Ethylenediamine as eluent component in cation chromatography. Predictive and comparative study for analysis of alkaline earth ions  

Microsoft Academic Search

The retention behaviour of alkaline earth cations was studied as a function of changing composition of acidified ethylenediamine eluent. The multiple eluent species retention model developed for separation of calcium, magnesium and strontium ions was utilized for determination of selectivity coefficients for sample and eluent ions. The suggested model accurately describes and predicts retention of analytes under elution conditions [0.5–2.0

Péter Hajós

2002-01-01

369

Automated Gain Control and Internal Calibration With External Ion Accumulation Capillary liquid chromatography-electrospray ionization-fourier transform ion cyclotron resonance.  

SciTech Connect

When combined with capillary LC separations, Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FTICR MS) has increasingly been applied for advanced characterization of proteolytic digests. Incorporation of external (to the ICR cell) ion accumulation multipoles with FTICR for ion pre selection and accumulation has enhanced the dynamic range, sensitivity and duty cycle of measurements. However, the highly variable ion production rate from an LC separation can result in overfilling of the external trap, resulting in m/z discrimination and fragmentation of peptide ions. An excessive space charge trapped in the ICR cell causes significant shifts in the detected ion cyclotron frequencies, reducing the achievable mass measurement accuracy (MMA) for protein identification. To eliminate m/z discrimination in the external ion trap, further increase the duty cycle and improve MMA, we developed a capability for data-dependent adjustment of ion accumulation times in the course of an LC separation, referred to as Automated Gain Control (AGC), in combination with low kinetic energy gated ion trapping and internal calibration using a dual-channel electrodynamic ion funnel. The system was initially evaluated in the analysis of a 0.5 mg/mL tryptic digest of bovine serum albumin. The implementation of LC/ESI/AGC/FTICR with internal calibration gave rise to a {approx} 10-fold increase in the number of identified tryptic peptides within mass measurement accuracy of 2 ppm as compared to that detected during the conventional LC/FTICR run with a fixed ion accumulation time and external calibration.

Belov, Mikhail E.(VISITORS) [VISITORS; Zhang, Rui (BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Strittmatter, Eric F.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Prior, David C.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Tang, Keqi (BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Smith, Richard D.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

2003-08-15

370

Effect of anionic ion-pairing reagent concentration (1-60 mM) on reversed-phase liquid chromatography elution behaviour of peptides.  

PubMed

The homologous series of volatile perfluorinated acids-trifluoroacetic acid (TFA), pentafluoropropionic acid (PFPA) and heptafluorobutyric acid (HFBA)--continue to be excellent anionic ion-pairing reagents for reversed-phase high-performance liquid chromatography (RP-HPLC) after more than two decades since their introduction to this field. It was felt that a thorough, step-by-step re-examination of the effects of anionic ion-pairing reagents over a wide concentration range on RP-HPLC peptide elution behaviour is now due, particularly considering the continuing dominance of such reagents for peptide applications. Thus, RP-HPLC was applied over a range of 1-60 mM phosphoric acid, TFA, PFPA and HFBA to two mixtures of 18-residue synthetic peptides containing either the same net positive charge (+4) or varying positive charge (+1, +2, +3, +4). Peptides with the same charge are resolved very similarly independent of the ion-pairing reagent used, although the overall retention times of the peptides increase with increasing hydrophobicity of the anion: phosphate < TFA- < PFPA- < HFBA-. Peptides of differing charge move at differing rates relative to each other depending on concentration of ion-pairing reagents. All four ion-pairing reagents increased peptide retention time with increasing concentration, albeit to different extents, again based on hydrophobicity of the anion, i.e., the more hydrophobic the anion, the greater the increase in peptide retention time at the same reagent concentration. Interestingly, phosphoric acid produced the best separation of the four-peptide mixture (+1 to +4 net charge). In addition, concentrations above 10 mM HFBA produced a reversal of the elution order of the four peptides (+1 < + 2 < + 3 < + 4) compared to the elution order produced by the other three reagents over the entire concentration range (+4 < + 3 < + 2 < + 1). PMID:16013615

Shibue, M; Mant, C T; Hodges, R S

2005-07-01

371

On-line capillary liquid chromatography tandem mass spectrometry on an ion trap\\/ reflectron time-of-flight mass spectrometer using the sequence tag database search approach for peptide sequencing and protein identification  

Microsoft Academic Search

Capillary high-performance liquid chromatography has been coupled on-line with an ion trap storage\\/reflectron time-of-flight\\u000a mass spectrometer to perform tandem mass spectrometry for tryptic peptides. Selection and fragmentation of the precursor ions\\u000a were performed in a three-dimensional ion trap, and the resulting fragment ions were pulsed out of the trap into a reflectron\\u000a time-of-flight mass spectrometer for mass analysis. The stored

Peiqing Huang; Daniel B. Wall; Stephen Parus; David M. Lubman

2000-01-01

372

Mass Spectrometry Parameters Optimization for the 46 Multiclass Pesticides Determination in Strawberries with Gas Chromatography Ion-Trap Tandem Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Multiclass analysis method was optimized in order to analyze pesticides traces by gas chromatography with ion-trap and tandem mass spectrometry (GC-MS/MS). The influence of some analytical parameters on pesticide signal response was explored. Five ion trap mass spectrometry (IT-MS) operating parameters, including isolation time (IT), excitation voltage (EV), excitation time (ET), maximum excitation energy or " q" value (q), and isolation mass window (IMW) were numerically tested in order to maximize the instrument analytical signal response. For this, multiple linear regression was used in data analysis to evaluate the influence of the five parameters on the analytical response in the ion trap mass spectrometer and to predict its response. The assessment of the five parameters based on the regression equations substantially increased the sensitivity of IT-MS/MS in the MS/MS mode. The results obtained show that for most of the pesticides, these parameters have a strong influence on both signal response and detection limit. Using the optimized method, a multiclass pesticide analysis was performed for 46 pesticides in a strawberry matrix. Levels higher than the limit established for strawberries by the European Union were found in some samples.

Fernandes, Virgínia C.; Vera, Jose L.; Domingues, Valentina F.; Silva, Luís M. S.; Mateus, Nuno; Delerue-Matos, Cristina

2012-12-01

373

Determination of free-form amphetamine in rat brain by ion-pair liquid chromatography-electrospray mass spectrometry with in vivo microdialysis.  

PubMed

An ion-pair liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) method with in vivo microdialysis for the determination of free-form amphetamine in rat brain has been developed. A microdialysis probe was surgically implanted into the striatum of the rat and artificial cerebrospinal fluid (aCSF) was used as the perfusion medium. Samples were collected and then analyzed off-line by LC-ESI-MS. A reversed phase C18 column was employed for LC separation. Trifluoroacetic acid (TFA) was added in the mobile phase (acetonitrile-water, 10:90, v/v) as an ion-pair reagent. The ion-pair process disguises the protonated amphetamine cations from the ESI-MS electric field as neutral molecules. Post-column addition of volatile organic acid was utilized to minimize TFA signal suppression effect on ESI-MS detection. More than six-fold enhancement of ESI-MS response was achieved by the post-column addition of propionic acid. Good linearity (0.01-1.00 microg/ml, r2 = 0.99) and detection limit (0.002 microg/ml) were determined. Good precision and accuracy were obtained. The applicability of this newly developed method was demonstrated by continuous monitoring of amphetamine concentrations in rat brain after a single 3.0 mg/kg i.p. administration. PMID:15058583

Fuh, Ming-Ren; Haung, Chiuan-Hung; Lin, Shiang-Ling; Pan, Wynn H T

2004-03-26

374

The development of a data system for a combination of liquid chromatography or capillary electrophoresis with an ion trap storage/reflectron time-of-flight mass detector.  

PubMed

A data system based upon a 200 MHz transient recorder interface card in a Pentium PC computer is demonstrated for on-line analysis of microbore high-performance liquid chromatography (HPLC), capillary HPLC and capillary electrophoresis (CE) separations using a fast and sensitive ion-trap storage/reflectron time-of-flight mass spectrometric detector (IT-reTOFMS). Under the control of a user-written program, the system is capable of conducting the data acquisition and storage for a minimum of 30 min, at rates exceeding 10 Hz, of individual mass spectra containing 16,000 data points having 10 nsec resolution. The capability is mainly attributed to the use of a data reduction scheme in which only mass intensities higher than a preset threshold are saved as indexed flight-time/intensity pairs. This produces a typical reduction ratio of 30:1 in data set size, yielding faster storage with smaller file size, and permits the complete set of mass spectra to be held in the computer's memory. In addition, the data system is capable of displaying, for real-time evaluation of the analysis, each individual mass spectrum and the total-ion chromatogram. Further, the selected-ion chromatograms of given masses and a 3-dimensional topographic map describing a separation process can be rapidly generated from the collected data for the unambiguous and high fidelity identification of target analytes in a complex mixture. PMID:8759329

Qian, M G; Wu, J T; Parus, S; Lubman, D M

1996-01-01

375

MSClust: a tool for unsupervised mass spectra extraction of chromatography-mass spectrometry ion-wise aligned data  

Microsoft Academic Search

Mass peak alignment (ion-wise alignment) has recently become a popular method for unsupervised data analysis in untargeted metabolic profiling. Here we present MSClust—a software tool for analysis GC–MS and LC–MS datasets derived from untargeted profiling. MSClust performs data reduction using unsupervised clustering and extraction of putative metabolite mass spectra from ion-wise chromatographic alignment data. The algorithm is based on the

Y. M. Tikunov; S. Laptenok; R. D. Hall; A. G. Bovy; Vos de C. H

2012-01-01

376

Analysis of 19-nortestosterone residue in animal tissues by ion-trap gas chromatography-tandem mass spectrometry  

Microsoft Academic Search

A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone\\u000a (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with ?-glucuronidase from\\u000a Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol\\/L). Next, the homogenate was mixed with methanol and heated at 60 °C\\u000a for 15 min, then placed

Jin-qing Jiang; Lei Zhang; Guang-ling Li; Hai-tang Zhang; Xue-feng Yang; Jun-wei Liu; Ren-feng Li; Zi-liang Wang; Jian-hua Wang

2011-01-01

377

On-line coupling of ion chromatography and atomic spectrometry for ultra trace analysis in high purity molybdenum- and tungsten-silicide.  

PubMed

The well-established technique of on-line coupling ion chromatography and atomic spectrometry for ultra trace analysis in high purity molybdenum and tungsten is extended to include the silicides MoSi(x) and WSi(x). An additionally included matrix elimination step allows an almost interference-free trace analysis in the silicide matrices. Reproducibility and accuracy of the on-line method were checked by comparison with several other methods, such as isotope dilution, radiochemical neutron activation analysis, direct determination by atomic absorption analysis and not at least with glow discharge mass spectrometry. The results show the high potential of the on-line method for reaching detection limits in the pg g(-1) range, but they show also remaining problems with contamination and system calibration. PMID:15048389

Seubert, A

1996-03-01

378

Simultaneous Quantification of Sinigrin, Sinalbin, and Anionic Glucosinolate Hydrolysis Products in Brassica juncea and Sinapis alba Seed Extracts Using Ion Chromatography.  

PubMed

Although mustards such as Sinapis alba and Brassica juncea contain glucosinolates (sinalbin and sinigrin, respectively) that hydrolyze to form biopesticidal products, routine quality control methods to measure active ingredients in seed and seed meals are lacking. We present a simple and fast ion chromatography method for the simultaneous quantification of sinigrin, sinalbin, and anionic hydrolysis products in mustard seed to assess biological potency. Optimum conditions include isocratic elution with 100 mM NaOH at a flow rate of 0.9 mL/min on a 4 × 210 mm hydroxide-selective anion-exchange column. All anion analytes including sinigrin, sinalbin, SO4(2-), and SCN(-) yielded recoveries ranging from 83 to 102% and limits of detection ?0.04 mM, with samples displaying little interference from plant matrix components. Sample preparation is minimized and analysis times are shortened to <90 min as compared with previous methods that took days and multiple instruments. PMID:25314611

Popova, Inna E; Morra, Matthew J

2014-11-01

379

Inductively coupled plasma mass spectrometry in comparison with neutron activation and ion chromatography with UV/VIS detection for the determination of lanthanides in plant materials.  

PubMed

Analytical performance of inductively coupled plasma mass spectrometry (ICP-MS) for determination of lanthanides in plant materials was investigated and compared with neutron activation analysis (NAA) as well as ion chromatography (IC) with UV-VIS detection. Two sample preparation protocols were tested: (i) microwave assisted digestion by concentrated nitric acid; (ii) microwave digestion involving silica and fluoride removal, followed by the selective and quantitative lanthanides group separation from the plant matrix. Several Certified Reference Materials (CRM) of plant origin were used for the evaluation of the accuracy of the applied analytical procedures. The consistency of results, obtained by various methods, enabled to establish the tentative recommended values (TRV) for several missing elements in one of CRMs. The ICP-MS, due to its very high sensitivity, has the potential to contribute to this aim. The discrepancy of the results obtained by various methods was discussed in a view of possible matrix effects related to the composition of investigated materials. PMID:22841084

Bulska, Ewa; Danko, Bo?ena; Dybczy?ski, Rajmund S; Krata, Agnieszka; Kulisa, Krzysztof; Samczy?ski, Zbigniew; Wojciechowski, Marcin

2012-08-15

380

The identification and quantification of a high molecular weight light stabilizer in polycarbonate by application of an online coupling of size exclusion chromatography in stopped flow mode with pyrolysis gas chromatography time of flight mass spectroscopy.  

PubMed

The identification and quantification of a high molecular weight light stabilizer (Uvinul 3030™) in an unknown polycarbonate sample was achieved through the application of SEC-Py-TOF-GCMS. A size exclusion column optimized to achieve resolution in the lower mass range was applied to allow the fractionation of an individual additive peak. A commercially available sampling interface was operated in stop flow mode and fractions were pyrolyzed to allow chromatographic separation of the fragments of the otherwise non-volatile stabilizer. After identification on the basis of accurate mass and elemental composition of the additive the quantification was compared using the available SEC-UV and SEC-PY-GC-TOFMS data. The resulting method provided a high degree of certainty in identification and flexibility in quantification expected to be applicable to other additives of similar volatilities or functional class. PMID:25160954

Brander, Eric; Wold, Christian

2014-10-01

381

Structural modifications of dicationic acetylcholinesterase reactivators studied under ion-pairing mechanism in reversed-phase liquid chromatography.  

PubMed

A study focused on the chromatographic behavior of several acetylcholinesterase reactivators under ion-pairing mechanism is reported. Among these reactivators, dicationic oximes and carbamoyl-based pyridinium congeners were studied, which form ion pairs with alkylsulfonate anions. This mechanism was studied for some major experimental parameters, such as the chain length of the ion-pairing agent added to the aqueous phase, its concentration, temperature, and nature of the organic modifier from mobile phase. Retention data showed one or two possibilities of forming ion pairs and the tautomerism of the studied reactivators, for different pH values of the aqueous component. Double sigmoid shapes were obtained for the studied compounds for the dependence between retention factor and pH, indicating the possibility of one or two tautomeric equilibria: at pH close to 7 these compounds are not stable as dicationic species and they participate in the retention process as nitroso forms, which are not able to form ion pairs with alkylsulfonates. The dependences of the retention factor on the organic modifier content from mobile phase were linear. Two complementary theoretical models were used to explain the functional dependences for the retention data on the experimental parameters. PMID:25141798

Radulescu, Medeea; Kuca, Kamil; Musilek, Kamil; David, Victor

2014-11-01

382

Chromatography Theory  

NSDL National Science Digital Library

James Hardy has produced a number of presentation-style lecture modules for analytical chemistry. This is a very good module that covers the introductory theory of chromatography. The material includes information on chromatography along with plate and kinetic theories. It is a colorful and well planned presentation of the introduction to chromatography that could be used as the basis for lectures on chromatography at the introductory analytical chemistry or instrumental analysis level.

2011-04-13

383

Affinity Chromatography  

NSDL National Science Digital Library

This is an experiment showing the application of affinity chromatography to the separation of albumin from horse serum. A brief introduction of affinity chromatography and how it is being used in this specific experiment is given. This appears to be a good experiment to show the advantages of affinity chromatography in separating specific proteins from a complex matrix and would be useful in a biochemistry course or a course that is specifically looking at differing types of chromatography.

Diresta, Dan

2011-05-23

384

Novel pre-fractionation method of trans fatty acids by gas chromatography with silver-ion cartridge column.  

PubMed

We developed a novel pre-separation method of trans fatty acids (TFAs) using a silver-ion cartridge column and GC. As a preliminary study, a mixture of fatty acid methyl esters consisting of saturated, cis-unsaturated, and trans-unsaturated fatty acids was dissolved in dichloromethane and loaded onto a Bond Elut SCX ion-exchange cartridge column that was converted to the silver-ion form. The column was then eluted with dichloromethane to obtain the saturated fatty acids, dichloromethane/ethyl acetate (90/10) for the trans mono-ene, dichloromethane/ethyl acetate (65/35) for the cis mono-ene, dichloromethane/acetone (60/40) for the trans di-ene, and acetone/acetonitrile (80/20) for the others. Satisfactory separation of the cis/trans isomers was confirmed by GC analysis. To generalize this technique, the elution conditions of the ready-to-use Discovery Ag-ION SPE cartridge column were also optimized. Both cartridge columns had good separation, recovery, and repeatability. Peer laboratory verification was carried out between two laboratories using different production lots of the ready-to-use cartridge column, and the robustness of the product and reproducibility of the method were found to be satisfactory. This technique is therefore a powerful tool not only for routine analyses of TFAs in oils, fats, and foods but also for detailed analyses of TFAs in various research fields. PMID:22277887

Goto, Hirofumi; Shionoya, Noriko; Sugie, Megumi; Tominaga, Makoto; Shimelis, Olga; Taniguchi, Makoto; Igarashi, Tomoji; Hirata, Yoshiaki

2012-01-01

385

Effect of fouling on the capacity and breakthrough characteristics of a packed bed ion exchange chromatography column  

Microsoft Academic Search

This study examined the impact of fouling with yeast homogenate on capacity and breakthrough performance of an ion exchange packed bed column. Column performance was assessed by analysis of breakthrough curves obtained with BSA as a test protein. The overall impact of fouling on breakthrough performance depended heavily on the level of clarification of the feed stream. Challenging the column

Sun Chau Siu; Helen Baldascini; David C. Hearle; Mike Hoare; Nigel J. Titchener-Hooker

2006-01-01

386

Quantification of immunoglobulin G and characterization of process related impurities using coupled protein A and size exclusion high performance liquid chromatography.  

PubMed

The present work describes two HPLC-UV methods for multi-protein quantification using (i) only a Protein A sensor cartridge (Protein A HPLC) and (ii) the same Protein A cartridge in combination with a size exclusion HPLC column (PSEC-HPLC). The possibility to simultaneously quantify immunoglobulin G (IgG) besides a non-binding protein such as bovine serum albumin (BSA) increases the applicability of Protein A HPLC. Its most pronounced feature is its independence of the buffer system, pH-value and salt content of the investigated sample solvent, which includes cell media. A comparison with the state-of-the-art, the photometrical Bradford method, shows that Protein A HPLC is as sensitive as Bradford, but that it comes with an extended linear range of 4 orders of magnitude, ranging from 0.15 [microg abs] to 1 [mg abs] absolute injected protein amount. The applicability of the PSEC-HPLC method is demonstrated for the analysis of real cell culture feed samples. While Protein A binds IgG, the SEC-column distributes the feed impurities by their molecular weight. The peak area ratios of IgG and the feed impurities of interest are then plotted against the collected sample fraction. These Protein A-Size-Exclusion-Chromatographic diagrams (PSEC-plot) combine the performance information of feed impurities and IgG in a single plot. Further it is shown that both methods are suitable for the performance evaluation of antibody purification media using static as well as dynamic binding experiments performed on DEAE-Fractogel and Capto Adhere. The investigated test samples were "mock" protein solutions with increasing complexity ranging from simple PBS buffer to serum free cell media and "real" cell culture feed solutions. PMID:20580008

Horak, Jeannie; Ronacher, Alexander; Lindner, Wolfgang

2010-07-30

387

Organic solvent-free reversed-phase ion-pairing liquid chromatography coupled to atomic fluorescence spectrometry for organoarsenic species determination in several matrices.  

PubMed

A novel method has been developed to determine As-containing animal feed additives including roxarsone (ROX), p-arsanilic acid (p-ASA) and nitarsone (NIT), as well as other organic As species (dimethylarsonic acid (DMAA) and monomethylarsonic acid (MMAA)) by ion-pairing high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (IP-HPLC-HG-AFS). A simple isocratic reversed-phase (RP) HPLC method with a mobile phase containing citric acid and sodium hexanesulfonate (pH 2.0) was developed using a C(18) column. The use of an organic solvent free mobile phase turns this methodology into an environmentally friendly alternative. Several ion pair forming agents, such as sodium hexanesulfonate, tetrabutylammonium bisulfate and perfluoroheptanoic acid, were studied. The limits of detection for As species were calculated in standard solution and resulted to be 0.2, 0.5, 0.6, 1.6, and 1.6 ?g As L(-1) for MMAA, DMAA, p-ASA, ROX and NIT, respectively. This method exhibited convenient operation, high sensitivity and good repeatability. It was applied to As speciation in different samples including arugula, dog food, dog urine and chicken liver. PMID:21388170

Monasterio, Romina P; Londonio, Juan A; Farias, Silvia S; Smichowski, Patricia; Wuilloud, Rodolfo G

2011-04-27

388

Application of ultra-high pressure liquid chromatography linear ion-trap orbitrap to qualitative and quantitative assessment of pesticide residues.  

PubMed

The analysis of pesticides residues using a last generation high resolution and high mass accuracy hybrid linear ion trap-Orbitrap mass spectrometer (LTQ-Orbitrap-MS) was explored. Pesticides were extracted from fruits, fish, bees and sediments by QuEChERS and from water by solid-phase with Oasis HLB cartridges. Ultra-high pressure liquid chromatography (UHPLC)-LTQ-Orbitrap mass spectrometer acquired full scan MS data for quantification, and data dependent (dd) MS(2) and MS(3) product ion spectra for identification and/or confirmation. The regression coefficients (r(2)) for the calibration curves (two order of magnitude up to the lowest calibration level) in the study were ?0.99. The LODs for 54 validated compounds were ?2ngmL(-1) (analytical standards). The relative standard deviation (RSD), which was used to estimate precision, was always lower than 22%. The recovery of extraction and matrix effects ranged from 58 to 120% and from -92 to 52%, respectively. Mass accuracy was always ?4ppm, corresponding to a maximum mass error of 1.6millimass units (mmu). This procedure was then successfully applied to pesticide residues in a set of the above-mentioned food and environmental samples. In addition to target analytes, this method enables the simultaneous detection/identification of non-target pesticides, pharmaceuticals, drugs of abuse, mycotoxins, and their metabolites. PMID:24438835

Farré, M; Picó, Y; Barceló, D

2014-02-01

389

Determination of trace levels of herbicides and their degradation products in surface and ground waters by gas chromatography/ion-trap mass spectrometry  

USGS Publications Warehouse

A rapid, specific and highly sensitive method is described for the determination of several commonly used herbicides and their degradation products in surface and ground waters by using gas chromatography/ion-trap mass spectrometry. The compounds included atrazine, and its degradation products desethylatrazine and desisopropylatrazine; Simazine; Cyanazine; Metolachlor; and alachlor and its degradation products, 2-chloro-2', 6'-diethylacetanilide, 2-hydroxy-2', 6'-diethylacetanilide and 2,6-diethylaniline. The method was applied to surface-water samples collected from 16 different stations along the lower Mississippi River and its major tributaries, and ground-water samples beneath a cornfield in central Nebraska. Average recovery of a surrogate herbicide, terbuthylazine, was greater than 99%. Recoveries of the compounds of interest from river water spiked at environmental levels are also presented. Full-scan mass spectra of these compounds were obtained on 1 ng or less of analyte. Data were collected in the full-scan acquisition mode. Quantitation was based on a single characteristic ion for each compound. The detection limit was 60 pg with a signal-to-noise ratio of greater than 10:1.

Pereira, W. E.; Rostad, C. E.; Leiker, T. J.

1990-01-01

390

Quantitative analysis of intracellular coenzymes in Saccharomyces cerevisiae using ion pair reversed phase ultra high performance liquid chromatography tandem mass spectrometry.  

PubMed

A fast, sensitive and specific analytical method, based on ion pair reversed phase ultrahigh performance liquid chromatography tandem mass spectrometry, IP-RP-UHPLC-MS/MS, was developed for quantitative determination of intracellular coenzyme A (CoA), acetyl CoA, succinyl CoA, phenylacetyl CoA, flavin mononucleotide, (FMN), flavin adenine dinucleotide, (FAD), NAD, NADH, NADP, NADPH. Dibutylammonium acetate (DBAA) was used as volatile ion pair reagent in the mobile phase. Addition of DBAA to the sample solutions resulted in an enhanced sensitivity for the phosphorylated coenzymes. Tris (2-carboxyethyl) phosphine hydrochloride (TCEP·HCl), was added to keep CoA in the reduced form. Isotope dilution mass spectrometry (IDMS) was applied for quantitative measurements for which culture derived global U-(13)C-labeled cell extract was used as internal standard. The analytical method was validated by determining the limit of detection, the limit of quantification, repeatability and intermediate precision. The method was successfully applied for quantification of coenzymes in the cell extracts of Saccharomyces cerevisiae. PMID:24021835

Seifar, Reza Maleki; Ras, Cor; Deshmukh, Amit T; Bekers, Katelijne M; Suarez-Mendez, Camilo A; da Cruz, Ana L B; van Gulik, Walter M; Heijnen, Joseph J

2013-10-11

391

Quantiative determination of sulfonated aliphatic and aromatic surfactants in sewage sludge by ion-pair/supercritical fluid extraction and derivatization gas chromatography/mass spectrometry  

SciTech Connect

Secondary alkanesulfonate (SAS) and linear alkylbenzene-sulfonate (LAS) surfactants were quantitatively (> 90%) extracted from sewage sludges as their tetrabutylammonium ion pairs using 400 atm of supercritical CO[sub 2] for 5 min of static extraction followed by 10 min of dynamic extraction at 80[degrees]C. Ion pairs of SAS and LAS quantitatively formed butyl esters in the injection port of the gas chromatograph and were determined by gas chromatography/mass spectrometry without class fractionation of the sewage sludge extracts. Concentrations of SAS and LAS in sludges from five different sewage treatment plants ranged from 0.27 to 0.80 g/kg of dry sewage sludge and from 3.83 to 7.51 g/kg, respectively. Good reproducibility was achieved with RSDs of typically 5% for replicate extractions and analyses. Homologue and isomer distributions of SAS in sewage sludge indicated an enrichment of the more hydrophobic components in sewage sludge during sewage treatment. 25 refs., 5 figs., 5 tabs.

Field, J.A.; Field, T.M.; Giger, W. (Swiss Federal Inst. for Water Resources and Water Pollution Control, Duebendorf (Switzerland)); Miller, D.J.; Hawthorne, S.B. (Univ. of North Dakota, Grand Forks (United States))

1992-12-15

392

Monitoring of phosphorus oxide ion for analytical speciation of phosphite and phosphate in transgenic plants by high-performance liquid chromatography-inductively coupled plasma mass spectrometry.  

PubMed

Large amounts of phosphate fertilizers utilized in agriculture and their relatively poor efficiency are of high ecological and economic concern. Therefore, transgenic plants capable of metabolizing phosphite are being engineered. In support of this biotechnological task, analytical speciation of phosphorus in biological tissues is required. In this study, plant extracts were analyzed by liquid chromatography-inductively coupled plasma mass spectrometry at m/z of elemental phosphorus and phosphorus oxide ions. Using polymeric-based anion exchange column and millimolar concentration of nitric acid in potassium phthalate mobile phase (pH 2.5), phosphite and phosphate ions were baseline resolved with retention times 6.95 ± 0.03 and 7.90 ± 0.03 min and with a total chromatographic run time 10 min. The detection limits were 1.58 and 1.74 ?g P L(-1) at m/z 47, as compared to 2.18 and 2.04 ?g P L(-1) at m/z 31, respectively. The results obtained in real world samples for the two detection modes were in good agreement, yet signal acquisition at m/z 47 enabled better precision without collision/reaction cell (RSD below 2%) as compared to RSD around 4% obtained at m/z 31 using He-pressurized cell (3.5 mL min(-1)). PMID:23782169

Torres Elguera, Julio Cesar; Yañez Barrientos, Eunice; Wrobel, Katarzyna; Wrobel, Kazimierz

2013-07-10

393

Rapid analysis of trace levels of antibiotic polyether ionophores in surface water by solid-phase extraction and liquid chromatography with ion trap tandem mass spectrometric detection.  

PubMed

The occurrence of antibiotics in surface and ground water is an emerging area of interest due to the potential impacts of these compounds on the environment. This paper details a rapid, sensitive and reliable analytical method for the determination of monensin A and B, salinomycin and narasin A in surface water using solid-phase extraction (SPE) and liquid chromatography-ion trap tandem mass spectrometry (LC-MS-MS) with selected reaction monitoring (SRM). Several product ions as sodiated sodium salts for MS-MS detection have been identified and documented with their proposed fragmentation pathways. Statistical analysis for determination of the method detection limit (MDL), accuracy and precision of the method is described. The average recovery of ionophore antibiotics in pristine and wastewater-influenced water was 96.0+/-8.3% and 93.8+/-9.1%, respectively. No matrix effect was seen with the surface water. MDL was between 0.03 and 0.05 microg/L for these antibiotic compounds in the surface water. The accuracy and day-to-day variation of method fell within acceptable ranges. The method is applied to evaluate to the occurrence of these compounds in a small watershed in Northern Colorado. The method verified the presence of trace levels of these antibiotics in urban and agricultural land use dominated sections of the river. PMID:15782964

Cha, J M; Yang, S; Carlson, K H

2005-02-18

394

Gas chromatography-ion trap mass spectrometry method for the simultaneous measurement of MDMA (ecstasy) and its metabolites, MDA, HMA, and HMMA in plasma and urine.  

PubMed

The investigation of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) abuse requires very robust methods with high sensitivity and wide linearity ranges for the quantification of this drug of abuse and its main metabolites in body fluids. An optimized gas chromatography-ion trap mass spectrometry (GC-IT/MS) methodology with electron impact ionization addressing these issues is presented. The sample preparation involves an enzymatic hydrolysis of urine and plasma for conjugate cleavage, a SPE extraction, and a derivatization process. The method was fully validated in rat plasma and urine. Linearity for a wide concentration range was achieved for MDMA, and the metabolites 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxyamphetamine (HMA) and 4-hydroxy-3-methoxymethamphetamine (HMMA). Limits of quantification were 2 ng/mL in plasma and 3.5 ng/mL in urine using a Selected Ion Monitoring detection mode. Selectivity, accuracy, precision, and recovery met the required criteria for the method validation. This GC-IT/MS method provides high sensitivity and adequate performance characteristics for the simultaneous quantification of MDMA, MDA, HMA and HMMA in the studied matrices. PMID:20167546

da Silva, Daniel Gomes; de Pinho, Paula Guedes; Pontes, Helena; Ferreira, Luísa; Branco, Paula; Remião, Fernando; Carvalho, Félix; Bastos, M Lurdes; Carmo, Helena

2010-03-15

395

Determination of amphetamine in rat brain by in vivo microdialysis and ion-pairing liquid chromatography with electrospray tandem mass spectrometry.  

PubMed

An ion-pairing liquid chromatography/electrospray tandem mass spectrometry (LC/ES-MS/MS) method with in vivo microdialysis for the determination of amphetamine in rat brain has been developed. A microdialysis probe was surgically implanted into the striatum of the rat and artificial cerebrospinal fluid (aCSF) was used as the perfusion medium. Samples were collected and then analyzed off-line by LC/ES-MS/MS. A reversed-phase C18 column was employed for LC separation and MS/MS was utilized for detection. Trifluoroacetic acid (TFA) was added to the mobile phase (acetonitrile/water) as an ion-pairing reagent. Detection was by ES-MS/MS directly, and no post-column addition of organic modifier was needed. Dual linear ranges were determined from 0.1-0.5 microg/mL and 0.005-0.1 microg/mL, respectively. The detection limit, based on a signal-to-noise ratio of 3, was 0.001 microg/mL (5 nM). Good precision and accuracy were obtained. The applicability of this newly developed method was demonstrated by continuous monitoring of amphetamine concentrations in rat brain. Amphetamine reached a maximum concentration of 0.086 +/- 0.017 microg/mL over 20-40 min after a single 3.0 mg/kg intraperitoneal administration. PMID:15282769

Fuh, Ming-Ren; Haung, Chiuan-Hung; Wu, Ti-Yu; Lin, Shiang-Ling; Pan, Wynn H T

2004-01-01

396

Quantitative Phosphoproteome Analysis of Lysophosphatidic Acid Induced Chemotaxis applying Dual-step ¹?O Labeling Coupled with Immobilized Metal-ion Affinity Chromatography  

SciTech Connect

Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in a variety of different cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its applications for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed 16O/18O labeling plus 16O/18O-methanol esterification labeling for quantitation, a macro- Immobilized Metal-ion Affinity Chromatography trap for phosphopeptide enrichment, and a monolithic capillary column with integrated electrospray emitter. LC separation and MS/MS is followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer and complementary searching algorithms for interpreting MS/MS spectra. Protein phosphorylation involved in various signaling pathways of cell migration were identified and quantified, such as mitogen-activated protein kinase 1, dual-specificity mitogen-activated protein kinase kinase 2, and dual-specificity tyrosine-phosphorylation regulated kinase 1b, and a number of Rho GTPase-activating proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with gradient sensing and cell chemotaxis.

Ding, Shi-Jian; Wang, Yingchun; Jacobs, Jon M.; Qian, Weijun; Yang, Feng; Tolmachev, Aleksey V.; Du, Xiuxia; Wang, Wei; Moore, Ronald J.; Monroe, Matthew E.; Purvine, Samuel O.; Waters, Katrina M.; Heibeck, Tyler H.; Adkins, Joshua N.; Camp, David G.; Klemke, Richard L.; Smith, Richard D.

2008-10-01

397

Detection and quantification of 1,N6-ethenoadenine in human urine by stable isotope dilution capillary gas chromatography/negative ion chemical ionization/mass spectrometry.  

PubMed

1,N(6)-Ethenoadenine (epsilonAde) is a promutagenic lesion detected in tissue DNA; it has been shown that epsilonAde can be repaired by human DNA glycosylases, and it is expected to be excreted in urine. In this paper, we present for the first time detection and accurate quantification of epsilonAde in human urine samples by a highly sensitive and specific stable isotope dilution gas chromatography/negative ion chemical ionization/mass spectrometric assay (GC/NICI/MS). Analysis by GC/NICI/MS includes adduct enrichment by a solid phase extraction column, followed by electrophore labeling and postderivatization cleanup. Using selective ion monitoring mode, the assay allows quantification of 0.5 pg of epsilonAde in as little as 0.1 mL of the urine sample, which is equivalent to corresponding concentration quantification limit of 31 pM. Using this assay, concentrations of epsilonAde in the 24 h urine samples of 23 healthy individuals were determined, which ranged from 0 to 124 pg/mL. After we adjusted for creatinine, a statistically significant correlation was found between epsilonAde excretion and cigarette smoking in males (p = 0.03). Thus, this stable isotope dilution GC/NICI/MS assay offers a sensitive and accurate quantification of urinary epsilonAde as a potential biomarker for oxidative damage of DNA and repair. PMID:12971797

Chen, Hauh-Jyun Candy; Chiu, Wei-Loong

2003-09-01

398

Determination of sulphonated azo dyes in food by ion-pair liquid chromatography with photodiode array and electrospray mass spectrometry detection.  

PubMed

An ion-pair liquid chromatography method with on-line photodiode-array and electrospray mass spectrometry detection was developed to determine 10 commonly used sulphonated azo dyes (Tartrazine, Amaranth, New Coccine, Sunset Yellow FCF, Allura Red AC, Ponceau R, Ponceau 3R, Orange I, Orange II and Metanil Yellow) in food. A reversed phase C(18) column with gradient elution was utilized to separate these compounds. Triethylamine was added in the mobile phase as an ion-pair reagent for chromatographic separation. Photodiode-array detection was employed for quantitative determination and electrospray mass spectrometry was used for identification. Good linearity (0.05-10 ppm, r(2)=0.999) and detection limit (<0.01 ppm) were determined with 5 mul injection. In addition, precision and accuracy associated with this newly developed method will be presented. A liquid extraction method was also developed to extract these dyes from different foodstuffs. The application of this method was demonstrated by analyzing sulphonated azo dyes in soft drinks, fruit jam, and salted vegetables. PMID:18968541

Fuh, Ming-Ren; Chia, Kan-Jung

2002-03-11

399

Simultaneous determination of imidacloprid and carbendazim in water samples by ion chromatography with fluorescence detector and post-column photochemical reactor.  

PubMed

A new analytical method has been developed and validated for the simultaneous determination of pesticides from different classes using ion chromatography-online photochemical derivatisation-fluorescence detector (IC-hv-FD). Fluorimetric detection was performed at ?ex/?em=332 nm/367 nm for imidacloprid and then detector was set at ?ex/?em=247 nm/470 nm for carbendazim. The two pesticides imidacloprid and carbendazim were successfully separated isocratically on an IonPac(®) AS11 (250 mm × 4 mm i.d; 13 µm particle size, Dionex) anion-exchange column using 40 mM KOH with 10% (v/v) acetonitrile and pumped at a flow rate of 1.0 mL min(-1). Under the optimized conditions, the limit of detection (LOD, S/N=3) of imidacloprid and carbendazim were 7.8 µg L(-1) and 67 µg L(-1), respectively. The experimental results showed that there was good linearity with a correlation coefficient (r)?0.9966 over the range of 0.05-10 mg L(-1) for imidacloprid and 0.2-15 mg L(-1) for carbendazim. Good reproducibility with a relative standard deviation (RSD, n=7) less than 4.5%. Finally, the proposed method was applied with satisfactory results to the analysis of these pesticides in ground water, lake water and river water without any pre-treatment of samples. The average spiked recoveries were in the range of 90-104%. PMID:24148383

Subhani, Qamar; Huang, Zhongping; Zhu, Zuoyi; Zhu, Yan

2013-11-15

400

Identification of indole alkaloids in Nauclea officinalis using high-performance liquid chromatography coupled with ion trap and time-of-flight mass spectrometry.  

PubMed

Indole alkaloids from Nauclea officinalis (Pierra ex Pitard) Merr are prospective agents for inflammation- related diseases. To speed up the process of discovering such bioactive compounds from natural origins, a mass spectrometry-based method was developed to screen N. officinalis for the presence of indole alkaloids. First, representative alkaloids were purified from herbs and analyzed using an ion trap (IT) mass spectrometer. Multi-stage mass spectra (MS(n))were utilized to establish the characteristic fragmentation pathways of indole alkaloids. It was shown that their fragmentation behaviors were correlated with the degree of unsaturation on ring-D of such alkaloids: if there is a double bond between C-3 and C-14, no fragments of ring cleavage are observed; otherwise, a fragment ion after reverse Diels-Alder cleavage of ring-D is observed as the base peak in their tandem mass spectrometry data. Then, herbal extracts of N. officinalis were analyzed using a combination of high- performance liquid chromatography (HPLC)/IT and HPLC/time-of-flight (ToF) systems. The structures of suspected alkaloids were deduced based on the accurate mass information from ToF and MS(n) from IT. Finally, a total of 10 indole and one indolizidine alkaloids were identified or tentatively characterized in extracts of N. officinalis. This work has demonstrated that the combination of MS(n) and ToF-MS can be used for rapid identification of monoterpenoid indole alkaloids in N. officinalis. PMID:21828417

Li, Qin; Zhang, Yufeng; Wu, Bin; Qu, Habin

2011-01-01

401

¹³C labelled internal standards--a solution to minimize ion suppression effects in liquid chromatography-tandem mass spectrometry analyses of drugs in biological samples?  

PubMed

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is frequently used to identify and quantify drugs in human biological samples due to the high selectivity and sensitivity of this technique. However, ion suppression effects caused by co-eluting compounds: drugs, metabolites, matrix components, impurities and degradation products, are a major concern. Stable isotope labelled internal standards (SIL ISs), usually deuterium ((2)H) labelled, are often used to compensate for these effects. In many LC separations the retention times of (2)H labelled ISs and their analogues will differ. Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) is increasingly being used for bio-analysis. With the better chromatographic resolution provided with sub 2 ?m particles, larger separation between analytes and their (2)H labelled analogues can be expected, which might reduce the benefits of the SIL IS. There is a greater difference in physico-chemical properties between hydrogen isotopes than between isotopes of other elements. (13)C, (15)N and (18)O labelled ISs are more similar to their analytes than (2)H labelled ISs and thereby expected to behave more similarly in chromatographic separations. In this study we have investigated the use of (13)C and (2)H labelled ISs for the determination of amphetamine and methamphetamine by UPLC-MS/MS. The (13)C labelled ISs were co eluting with their analytes under different chromatographic conditions while the (2)H labelled ISs and their analytes were slightly separated. An improved ability to compensate for ion suppression effects were observed when the (13)C labelled ISs were used. Furthermore, an UPLC-MS/MS method for determination of amphetamine and methamphetamine in urine using (13)C labelled ISs has been developed and validated. Unfortunately, there are few (13)C labelled ISs commercial available today. If more (13)C labelled ISs become commercial available they may well be the coming solution to minimize ion suppression/enhancement effects in LC-MS/MS analyses of drugs in biological samples. PMID:22119139

Berg, Thomas; Strand, Dag Helge

2011-12-30

402

ion-Exchange Paper Chromatography of Metal Ions with Mixed Aqueous-Organic Solvents Containing Mineral Acid and a Selective Extractant  

Microsoft Academic Search

Mixed solvents containing an organic extractant provide selective separations of metal ions on cation- and anion-exchange papers. The separations of scandium, hafnium plus zirconium, nickel, and thorium from complex mixtures are demonstrated. Various separations in dithizone and dimethyl-sulfoxide media are also reported. Results are often the same as those achieved on columns of resin with the same mobile phase.

Joseph Sherma; Frank J. Van Lenten

1971-01-01

403

Ion-paired extraction of cephalosporins in acetone prior to their analysis by capillary liquid chromatography in environmental water and meat samples.  

PubMed

Ion-pair extraction of cephalosporins from aqueous solution into acetone by the addition of ammonium sulfate to a 1:2 (v/v) acetone-water solvent was carried out followed by their determination using reversed-phase capillary liquid chromatography. The analytes included are cephoperazone, cefquinome, cephalexin, cephapirin, cephaloniun, cephamandole, cephazolin and cephadroxile. In order to form the ion-pair, hexadecyltrimethylammonium bromide (CTAB) was selected as cationic ion-pairing agent at a concentration of 0.9 mM using 10mM phosphate buffer at pH 8 as the optimum condition for the aqueous solution. The applied methodology, named salting-out assisted liquid/liquid extraction (SALLE) involves the use of 1.25 g of ammonium sulfate as salting-out agent. The separation of cephalosporins using a Luna C18 (150 mm × 0.3mm, 5 µm, 100 Å) column was achieved under the following conditions: a gradient program combining solvent A (0.1% formic acid in water, pH 4) and solvent B (acetonitrile-methanol (50:50, v/v)), at a flow rate of 20 µl min(-1), column temperature 35°C and injection volume 7 µl with UV detection at 250 nm. The limits of quantification for the studied compounds were between 4.3 and 22.7 ?g/L for water samples and 4.1 and 73.3 ?g/kg in the case of beef samples, lower than the maximum residue limits permitted by the EU for this kind of food. The developed methodology has demonstrated its suitability for the analysis of these widely applied antibiotics in environmental water and meat samples, including beef and pork muscle, with high sensitivity, precision and satisfactory recoveries. PMID:24054686

Quesada-Molina, Carolina; García-Campaña, Ana M; del Olmo-Iruela, Monsalud

2013-10-15

404

Ion-pairing and reversed phase liquid chromatography for the determination of three different quinolones: Enrofloxacin, lomefloxacin and ofloxacin  

Microsoft Academic Search

Two simple and sensitive high performance liquid chromatographic (HPLC) methods have been developed for the simultaneous determination of three different quinolones: enrofloxacin, lomefloxacin and ofloxacin in their pure and dosage forms, one with reversed phase HPLC and the other with ion-pair HPLC. In reversed phase HPLC, method (A), the mobile phase consists of 2.18% aqueous solution of KH2PO4 with pH

Alaa S. Amin; Hassan A. Dessouki; Ibrahim A. Agwa

2011-01-01

405

Analysis of condensed phosphates in food products by ion chromatography with an on-line hydroxide eluent generator  

Microsoft Academic Search

An ion chromatographic method with gradient elution using an automated eluent generator was developed for the simultaneous determination of condensed phosphates (CPs) such as orthophosphate (P1), pyrophosphate (P2), polyphosphate, trimetaphosphate and phytate in food products. The linear calibration curves for P1, P2, tripolyphosphate, and tetrapolyphosphate in the range 0.5–500 ?M had a correlation factor of 0.999 or better. The precision

Yoko Sekiguchi; Akinobu Matsunaga; Atsushi Yamamoto; Yoshinori Inoue

2000-01-01

406

Ion-pair reversed-phase chromatography of short double-stranded deoxyribonucleic acid in silicon micro-pillar array columns: retention model and applications.  

PubMed

Separation of double-stranded (ds) DNAs is important in numerous biochemical analyses relevant for clinical applications. A widely used separation technique is high performance liquid chromatography (HPLC), in the variant of ion-pair reversed-phase (IP-RP) chromatography. HPLC can be miniaturized by means of silicon micro-pillar array columns leading to on-chip fast and high resolution dsDNA separation with limited sample quantity. However, theoretical studies of retentive behavior of dsDNA in miniaturized chromatographic columns are hardly available, despite their enormous practical relevance. This paper established a new retention model to describe the size dependent separation of dsDNAs for any characteristic of the linear mobile phase gradient, in analogy to the model used to describe the retention of polymer chains with repeating units in RP HPLC. The model agrees with a large amount of dsDNA retention data, measured using DNA molecules in the size range of 10-400 base pairs in columns with different lengths (2 and 40cm) and different micro-pillar sizes (2 and 2.5?m in diameter), in various mobile phase gradients. The model is particularly useful in practice, since it requires no numerical solutions and the column-specific fitting parameters (4 or 5) can be determined in a limited number of separation runs. As examples of its applications, the model has been used for the optimization of dsDNA step-gradient separations (5 dsDNAs separated within 8min) and for the determination of the size of dsDNA fragment (with uncertainty of about 2%). These applications are especially relevant for on-chip DNA analysis devices. PMID:23647613

Zhang, Lei; Majeed, Bivragh; Lagae, Liesbet; Peumans, Peter; Van Hoof, Chris; De Malsche, Wim

2013-06-14

407

Isolation of Pu-isotopes from environmental samples using ion chromatography for accelerator mass spectrometry and alpha spectrometry.  

PubMed

A radiochemical method for the isolation of plutonium-isotopes from environmental samples, based on the use of specific extraction chromatography resins for actinides (TEVA), Eichrom Industries, Inc.), has been set up in our laboratory and optimised for their posterior determination by alpha spectrometry (AS) or accelerator mass spectrometry (AMS). The proposed radiochemical method has replaced in our lab a well-established one based on the use of a relatively un-specific anion-exchange resin (AG) 1X8, Bio-rad Laboratories, Inc.), because it is clearly less time consuming, reduces the amounts and molarities of acid wastes produced, and reproducibly gives high radiochemical yields. In order to check the reliability of the proposed radiochemical method for the determination of plutonium-isotopes in different environmental matrixes, twin aliquots of a set of samples were prepared with TEVA and with AG 1X8 resins and measured by AS. Some samples prepared with TEVA resins were measured as well by AMS. As it is shown in the text, there is a comfortable agreement between AS and AMS, which adequately validates the method. PMID:18082656

Chamizo, E; Jiménez-Ramos, M C; Wacker, L; Vioque, I; Calleja, A; García-León, M; García-Tenorio, R

2008-01-14

408

Detection of allantoin in clinical samples using hydrophilic liquid chromatography with stable isotope dilution negative ion tandem mass spectrometry.  

PubMed

Allantoin is the major oxidation product of urate in humans and is a potential biomarker of oxidative stress. Several methods are used to measure allantoin in biological samples but they have inherent issues that can include lack of specificity and sensitivity, difficulty in sample preparation, or artefactual generation of allantoin. We have developed a method for measuring allantoin using hydrophilic liquid chromatography with stable isotope dilution tandem mass spectrometry (HILIC-MS/MS). It was validated for measuring allantoin in plasma, synovial fluid and urine from human subjects. The limit of quantification was determined to be 10 fmol and the assay displayed excellent linearity for the wide range of concentrations found in clinical samples. Relative standard deviations were <5% for between-day and <7% for within-day variation. Accuracy was between 100% and 104%. Concentrations of allantoin in plasma of healthy controls (2.0 ?M; interquartile range 1.4-3.6 ?M, n=35) was significantly lower (p<0.001) than that in plasma from patients with rheumatoid arthritis (3.7 ?M; IQR 3.0-5.6 ?M, n=43) and in synovial fluid of patients with gout (3.3 ?M; IQR 2.8-5.8 ?M, n=10). This newer HILIC-MS/MS method is a simple and highly sensitive assay for detection of allantoin. It can be used to assess the level of oxidative stress in human pathologies. PMID:22398212

Turner, Rufus; Stamp, Lisa K; Kettle, Anthony J

2012-04-01

409

A study of bioactive, branched (1?3)-?-d-glucans in dimethylacetamide/LiCl and dimethyl sulphoxide/LiCl using size-exclusion chromatography with multi-angle light scattering detection.  

PubMed

Water-soluble (1?3)-?-d-glucans with 1,6-linked branches (SBG) isolated from the cell walls of Saccharomyces cerevisiae were studied by size exclusion chromatography (SEC) with multi-angle laser light scattering (MALLS) detector using dimethylacetamide (DMAc) containing 0.5% (0.12M) LiCl, or dimethyl sulphoxide (DMSO) in the absence and presence of 0.25M LiCl, respectively, as eluents. The aggregating glucan could be dispersed as single chains in both solvents, with chain length distributions in reasonable agreement with results obtained previously with carboxymethylated glucans in aqueous solvent. However, DMAc is preferred over DMSO because of higher sensitivity in MALLS, and also because the latter produces SEC anomalies. SBG dissolves slowly in DMAc/LICl at room temperature, but heating accelerates the process. The rate of depolymerisation of SBG in DMAc/LiCl at high temperatures (70-105°C) was determined as a basis for defining dissolution procedures at elevated temperatures with a minimum of degradation. The result of the investigation is a simple and reliable protocol for preparing unaggregated, fully dissolved and undegraded SBG in DMAc/LiCl, which is well suited as a standard analysis of the molecular weight distribution of SBG-like molecules without chemical derivatization. PMID:23891208

Qin, Fen; Kes, Mür?ide; Christensen, Bjørn E

2013-08-30

410

Scale-up potential of ion-pair high-performance liquid chromatography method to produce biologically active inositol phosphates.  

PubMed

This study was undertaken to evaluate the possibility that an analytical ion-pair HPLC procedure used to determine phytic acid (IP6) and its degradation products (IP3-IP5) can be transformed to a preparative purification method. A commercial phytic acid (CPA) preparation was separated into its component fractions of IP3, IP4, IPS, and IP6 on two C18 columns (1.8 and 4.2 ml) using 51% methanol containing 0.6-1% tetrabutylammonium hydroxide as ion-pair reagent and 0-0.025 M formic acid (pH 4.3) as eluent at 1.7 and 3.0 cm/min linear velocity, respectively, and 40 degrees C. Elution was monitored at 40 degrees C by a refractive index detector. Reproducible separation of CPA into four well-resolved peaks on these columns was possible after optimizing method variables, particularly the concentration of ion-pair reagent in the injected sample (>1.5%). The same separations were obtained after CPA loads were scaled up 25 times on a steel column (15 cm x 19 mm I.D.), packed with Ethyl C2 sorbent (10 microm) and on a 25 cm x 21.2 mm I.D. C18 column, but at a reduced linear velocity to increase the resolution. Therefore, this optimization of separation not only is useful for analysis of phytic acid and its degradation products but also it provides key parameters for scale up for further fractionation and characterization. PMID:11831759

Hamada, Jamel S

2002-01-25

411

Determination of alkali and alkaline earth elements along with nitrogen in uranium based nuclear fuel materials by ion chromatography (IC).  

PubMed

An accurate and sensitive ion chromatographic (IC) method with suppressed conductivity detection is described for determination of traces of Na, K, Mg and Ca along with nitrogen in uranium based materials. The method involves matrix separation after sample dissolution by hydrolyzing and filtering off the polyvalent cations. Transition elements interfering in the determination of Ca were removed by cation exchange cartridge containing iminodiacetate resin. Detection limits were between 2 and 6 microgL(-1) and overall precision were better than +/-5%. Recovery of spiked cations was in range from 96% to 104%. Results obtained were in good agreement with other methods. PMID:17904478

Verma, Poonam; Ramakumar, Karanam L

2007-10-01

412

Analysis of nine food additives in red wine by ion-suppression reversed-phase high-performance liquid chromatography using trifluoroacetic acid and ammonium acetate as ion-suppressors.  

PubMed

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in red wine. The effects of ion-suppressors, i.e., trifluoroacetic acid (TFA) and ammonium acetate (AmAc) on retention behavior of nine food additives in RP-HPLC separation were discussed in detail. The relationships between retention factors of solutes and volume percent of ion-suppressors in the mobile-phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, respectively. The results showed that the ion suppressors had not only an ion suppression effect, but also an organic modification effect on the acidic analytes. The baseline separation of nine food additives was completed by a gradient elution with acetonitrile-TFA(0.01%, v/v)-AmAc(2.5 mmol L(-1)) aqueous solution as the mobile phase. The recoveries were between 80.2 - 99.5% for all analytes with RSDs in the range of 1.5 - 8.9%. The linearities were in the range of 0.2 - 100.0 mg L(-1) with determination coefficients (r(2)) higher than 0.9991 for all analytes. The limits of quantification (LOQs) were between 0.53 - 0.99 mg L(-1). The applicability of the proposed method to detect and quantify food additives has been demonstrated in the analysis of 30 real samples. PMID:23059992

Zhao, Yong-Gang; Chen, Xiao-Hong; Yao, Shan-Shan; Pan, Sheng-Dong; Li, Xiao-Ping; Jin, Mi-Cong

2012-01-01

413

Express analysis of explosives, chemical warfare agents and drugs with multicapillary column gas chromatography and ion mobility increment spectrometry.  

PubMed

Description of a gas chromatograph designed for express analysis of explosives (2,4-dinitrotoluene, 2,4,6-trinitrotoluene, pentaerythritol tetranitrate), chemical warfare agents (mustard gas, lewisite, sarin) and drugs (heroin, cocaine hydrochloride, crack) is given. The devices comprises a multicapillary chromatographic column and an ion mobility increment spectrometer (MCC-IMIS). The main analytical characteristics of an IMIS (estimated detection limit (DL), linear dynamic range (LDR), speed of response) and a chromatographic column (separation power, degree of separation, a number of possible peaks at a chromatogram section, divided by analysis time) are determined. The maximum value of DL equal to 5 pg/ml was registered for cis-alpha-LW, and the lowest one of 0.001 pg/ml was for cocaine. The maximum value of LDR equal to 1000 was registered for sarin and the lowest one of 150 was for the ions of lewisite. Speed of response of one compound detection with the IMIS was 0.7 s. PMID:14698239

Buryakov, Igor A

2004-02-01

414

Study of anthocyanic profiles of twenty-one hybrid grape varieties by liquid chromatography and precursor-ion mass spectrometry.  

PubMed

The anthocyanins of 21 hybrid red varieties produced by crossing V. vinifera, V. riparia, V. labrusca, V. lincecumii and V. rupestris species, the profiles for which have not yet been reported, were studied. Profiles were determined by LC/DAD, and identification of single anthocyanins was confirmed by LC/MS precursor-ion analysis. Anthocyanidin precursors (pelargonidin at m/z 271, dephinidin at m/z 303, cyanidin at m/z 287, petunidin at m/z 317, peonidin at m/z 301, and malvidin at m/z 331) and precursors of monoglucoside compounds allowed 24 different compounds to be identified. Analysis of precursor ions of monoglucoside anthocyanins at low capillary voltage revealed the signals of diglucosides only, providing a very selective method for analysis of diglucoside anthocyanins in grape. According to anthocyanin profile, the samples were subdivided into two groups: one characterized by the substantial presence of diglucoside compounds (particularly Seyve Villard 23-399 and Seyve Villard 23-369) and one by the scarce presence or practical absence of diglucosides (Seibel 10878, Burdin 4077, and Galibert 238-35). Particularly interesting for producing anthocyanin for the natural colorant industry were the varieties Siebel 8357, Bacò 30-12 and Terzi 100-31. PMID:22688043

De Rosso, M; Tonidandel, L; Larcher, R; Nicolini, G; Ruggeri, V; Dalla Vedova, A; De Marchi, F; Gardiman, M; Flamini, R

2012-06-30

415

Simultaneous determination of four andrographolides in Andrographis paniculata Nees by silver ion reversed-phase high-performance liquid chromatography.  

PubMed

A rapid and sensitive silver ion high-performance liquid chromatographic (Ag[I]-HPLC) method is developed for the simultaneous determination of the biologically active diterpenoids andrographolide, 14-deoxy-11,12-didehydroandrographolide, 14-deoxyandrographolide, and neoandrographolide in Andrographis paniculata Nees. HPLC is carried out for determining andrographolide and its derivatives with methanol-water (55:45, v/v) as the mobile phase on a C18 column (5 microm, 150 mm x 4.6 mm i.d.) with UV detection at 205 nm. Four andrographolides are baseline separated in a novel way: by adding silver ions (0.005 mol L(-1)) to the previously mentioned mobile phase. Validation of the method challenges specificity, linearity, limit of detection, limit of quantitation, accuracy, and repeatability, and the results met the acceptance criteria for all analytes. The molecular mechanism of retention is demonstrated by comparing partition coefficients (logP) of different andrographolides and andrographolide-Ag(I) complexes. Thus, the method is successfully applied to characterize and determine the four andrographolides in Andrographis paniculata Nees extract and its commercial product. PMID:18796235

Xu, Tao; Pan, Jian; Zhao, Lingli

2008-09-01

416

Comparison of ion-specific electrode and high performance liquid chromatography methods for the determination of iodide in milk.  

PubMed

Two methods for the determination of I- in raw and processed milk were examined. A simple ion-specific electrode (ISE) method was compared against a more complex HPLC reference technique. Accuracy and precision were evaluated both within and between the 2 methods. Both methods yielded good recoveries for Ion spiked samples, ranging from 87 to 114% for ISE and 91 to 100% for HPLC. Within-run repeatability and between-run reproducibility were superior with the HPLC method, but were still more than acceptable with the ISE technique. Overall agreement of paired results between ISE and HPLC methods was good (r2 = 0.85 on raw herd milk; r2 = 0.84 on processed milk). The ISE method had a significant positive bias relative to the HPLC reference method. Both methods lend themselves well to the measurement of I- in raw or processed milk. Given its relatively low cost and ease of use, the ISE method is well suited as a screening method. The impressive accuracy, precision, selectivity, and limit of detection of the HPLC technique make it an ideal confirmation method. PMID:16507687

Melichercik, J; Szijarto, L; Hill, A R

2006-03-01

417

ELSEVIER Journal of Chromatography A, 693 (1995) 197-203 CHROMATOGRAPHYA  

E-print Network

ELSEVIER Journal of Chromatography A, 693 (1995) 197-203 JOURNALOF CHROMATOGRAPHYA Adsorptive interaction of Ficoll standards with porous glass size-exclusion chromatography columns Gita Shah, Paul L in chromatographic and porous media. Calibrating porous glass size-exclusion chromatography columns with Ficoll, we

Dubin, Paul D.

418

Reverse phase high speed liquid chromatography of antibiotics. III. Use of ultra high performance columns and ion-pairing techniques.  

PubMed

Improved methods for the separation and quantitation of cephalosporin, penicillin, aminoglycoside and anthracycline antibiotics are presented. The use of ultra high performance 5 micrometer phase columns combined with the added dimension of ion-pairing greatly increases the ease of separation and speed of analysis of complex antibiotic mixtures. Antibiotics in a variety of dosage forms and in fermentation broths have been examined in order to provide the maximum data on impurities to meet regulatory requirements for drug safety, purity and efficacy. Mixtures of antibiotics have been analyzed to demonstrate the improved separations, increased efficiency and shortened analysis times possible with ultra thin performance columns. Under these improved conditions, the danger of multiple components in a single peak are markedly reduced. PMID:6945300

White, E R; Zarembo, J E

1981-07-01

419

Analysis of cyanobacterial-derived saxitoxins using high-performance ion exchange chromatography with chemical oxidation/fluorescence detection.  

PubMed

A single run HPLC method utilizing ion exchange as the separation mode with a novel mobile phase system coupled to chemical postcolumn oxidation and fluorescence detection has been developed and demonstrated to be applicable to the quantitative analysis of paralytic shellfish poisons (PSPs) produced by Australian cyanobacteria (Anabaena circinalis) and other cyanobacteria. Both the cyanobacterial matrix and natural water constituents did not significantly affect the performance of this method. The daily precision of this method was adequate for it to be considered as a routine analytical tool for direct PSP analysis (prePSP concentration is not required) of cyanobacterial extracts and water bodies containing PSPs (C1, C2, GTX2, GTX3, NEO, STX) in the low parts per billion concentration range (10-70 ppb). PMID:16302175

Papageorgiou, John; Nicholson, Brenton C; Linke, Thomas A; Kapralos, Con

2005-12-01

420

Alignment of retention time obtained from multicapillary column gas chromatography used for VOC analysis with ion mobility spectrometry  

PubMed Central

Multicapillary column (MCC) ion mobility spectrometers (IMS) are increasingly in demand for medical diagnosis, biological applications and process control. In a MCC-IMS, volatile compounds are differentiated by specific retention time and ion mobility when rapid preseparation techniques are applied, e.g. for the analysis of complex and humid samples. Therefore, high accuracy in the determination of both parameters is required for reliable identification of the signals. The retention time in the MCC is the subject of the present investigation because, for such columns, small deviations in temperature and flow velocity may cause significant changes in retention time. Therefore, a universal correction procedure would be a helpful tool to increase the accuracy of the data obtained from a gas-chromatographic preseparation. Although the effect of the carrier gas flow velocity and temperature on retention time is not linear, it could be demonstrated that a linear alignment can compensate for the changes in retention time due to common minor deviations of both the carrier gas flow velocity and the column temperature around the MCC-IMS standard operation conditions. Therefore, an effective linear alignment procedure for the correction of those deviations has been developed from the analyses of defined gas mixtures under various experimental conditions. This procedure was then applied to data sets generated from real breath analyses obtained in clinical studies using different instruments at different measuring sites for validation. The variation in the retention time of known signals, especially for compounds with higher retention times, was significantly improved. The alignment of the retention time—an indispensable procedure to achieve a more precise identification of analytes—using the proposed method reduces the random error caused by small accidental deviations in column temperature and flow velocity significantly. PMID:20512565

Bodeker, Bertram; Junger, Melanie; Nolte, Jurgen; Vautz, Wolfgang

2010-01-01