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1

Ion exclusion chromatography of aromatic acids.  

PubMed

The determination of aromatic acids by ion exclusion chromatography is challenging due to peak tailing and the long retention time of hydrophobic solutes. This review discusses the retention mechanisms and the factors affecting retention, eluents and detection methods used in ion exclusion chromatography of aromatic acids such as mono-, di-, tri- and tetra-carboxylic acids, amino acids, sulfonates and phenol. In addition, the different approaches used to improve the chromatographic separation of these compounds are also discussed. These approaches include introducing an internal gradient of the ionic strength, using vacancy ion exclusion chromatography, employing a hydrophilic cation exchange resin or adding a modifier such as heptanol to the dilute sulfuric acid mobile phase. The applications of these methods in the analysis of aromatic acids are provided with a table summarizing the stationary phases, the mobile phases and the detection methods. PMID:23420808

Mansour, Fotouh R; Kirkpatrick, Christine L; Danielson, Neil D

2013-02-17

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

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

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

Simultaneous determination of anions and cations by ion-exclusion chromatography–cation-exchange chromatography with tartaric acid\\/18-crown-6 as eluent  

Microsoft Academic Search

Ion-exclusion chromatography–cation-exchange chromatography was developed for the simultaneous separation of common inorganic anions and cations (Cl?, NO3? and SO42?; Na+, NH4+, K+, Mg2+ and Ca2+) on a weakly acidic cation-exchange column by elution with weak acid. Generally, the resolution among these monovalent cations was only moderate, thereby hindering the determination of these analytes in natural-water samples. Therefore, 18-crown-6 was added

Se-Mog Kwon; Kwang-Pill Lee; Kazuhiko Tanaka; Kazutoku Ohta

1999-01-01

6

Indirect UV detection-ion-exclusion/cation-exchange chromatography of common inorganic ions with sulfosalicylic acid eluent.  

PubMed

Herein, we describe indirect UV detection-ion-exclusion/cation-exchange chromatography (IEC/CEC) on a weakly acidic cation-exchange resin in the H(+)-form (TSKgel Super IC-A/C) using sulfosalicylic acid as the eluent. The goal of the study was to characterize the peaks detected by UV detector. The peak directions of analyte ions in UV at 315 nm were negative because the molar absorbance coefficients of analyte anions and cations were lower than that of the sulfosalicylic acid eluent. Good chromatographic resolution and high signal-to-noise ratios of analyte ions were obtained for the separations performed using 1.1 mM sulfosalicylic acid and 1.5 mM 18-crown-6 as the eluent. The relative standard deviations (RSDs) of the peak areas ranged from 0.6 to 4.9%. Lower detection limits of the analytes were achieved using indirect UV detection at 315 nm (0.23 - 0.98 ?M) than those obtained with conductometric detection (CD) (0.61 - 2.1 ?M) under the optimized elution conditions. The calibration curves were linear in the range from 0.01 to 1.0 mM except for Cl(-), which was from 0.02 to 2.0 mM. The present method was successfully applied to determine common inorganic ions in a pond water sample. PMID:23303096

Kozaki, Daisuke; Mori, Masanobu; Nakatani, Nobutake; Arai, Kaori; Masuno, Tomoe; Koseki, Masakazu; Itabashi, Hideyuki; Tanaka, Kazuhiko

2013-01-01

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)

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

[Simultaneous determination of 11 organic acids in fruit juice by ion exclusion chromatography].  

PubMed

A method for the quantitative determination of 11 organic acids (oxalic acid, citric acid, tartaric acid, malic acid, ascorbic acid, lactic acid, succinic acid, formic acid, acetic acid, glutaric acid and fumaric acid) in fruit juice was developed successfully. It was based on an ion exclusion chromatographic separation under the conditions of isocratic elution with 17 mmol/L sulphuric acid solution with the ICE-ION-300 ion exclusion column, and the UV detection at 210 nm. The precision of the method was investigated and the relative standard deviations were from 1.5% to 9.8% (n = 10). PMID:12541818

Guo, D H; Xia, L

2001-05-01

11

Determination of volatile fatty acids in landfill leachates by ion-exclusion chromatography.  

PubMed

An ion-exclusion chromatographic method with on-line desalinization for the determination of volatile fatty acids in landfill leachates is described. Highly sensitive conductivity detection of the organic acids was achieved by using dilute p-hydroxybenzoic acid solution as an eluent. Interference with mineral acids was reduced by treatment with barium chloride solution prior to desalinization. A silver-loaded cation-exchange guard column for the desalinization was installed in series with the analytical column to avoid the contamination of organic acids. This method features detection limits of 0.01 mg L(-1) formic acid, 0.02 mg L(-1) acetic acid, 0.05 mg L(-1) propionic acid, and 0.1 mg L(-1) butyric acid, respectively, with an injection of 20 microL sample. Application of the on-line desalinization LC method is illustrated for leachate samples from a Japanese sanitary landfill. PMID:15334921

Yamamoto, Atsushi; Yasuhara, Akio; Kodama, Shuji; Matsunaga, Akinobu; Suzuki, Shigeru; Mohri, Shino; Yamada, Masato

2004-03-01

12

Size Exclusion Chromatography (SEC) in Aqueous Media  

Microsoft Academic Search

This thesis deals with the different aspects of the successful application of size exclusion chromatography (SEC) for the molecular weight distribution (MWD) measurement of water soluble polymers. These aspects include methodology of mobile-phase development, selection of packing pore-sizes and methodology of molecular weight calibration and chromatogram interpretation. Qualitative understanding of ion-exclusion and adsorption, two of the more important and least

Sunny Nosakhare Ebilamiagbon

1980-01-01

13

Ion Exchange Chromatography  

NSDL National Science Digital Library

This website contains an ion chromatography simulator that can be run online or can be downloaded. The simulator focuses on separations of proteins using Ion Chromatography. Also included is linked reference information, an example of a homework assignment using the simulator, and some information on protein structures.

2011-05-23

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

Micelle exclusion chromatography of heavy-metal cations  

SciTech Connect

Micelle exclusion chromatography, wherein a micellar mobile phase and a size exclusion column are utilized for ionic separation, was applied to the separation of heavy-metal cations. Usefulness of simple micelle exclusion chromatography was limited by the poor resolution of metal cations, but addition of complexing agents in the sodium dodecyl sulfate eluent made possible the simultaneous separation of many divalent and trivalent transition- and rare-earth-metal cations. Additionally, the chromatographic retention behavior was used to calculate partition coefficients of metal ions between micelles and the bulk solution and between the imbibed solution and the stationary phase.

Okada, T.

1988-10-01

16

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

17

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

18

Non-suppressed conductivity and indirect UV detection of carboxylic acids in environmental samples by ion-exclusion chromatography using 2,6-pyridinedicarboxylic acidic eluent.  

PubMed

2,6-Pyridinedicarboxylic acid (PDCA) was evaluated as an eluent for indirect UV and non-suppressed conductivity detection of carboxylic acids in ion-exclusion chromatography. The effect of PDCA concentration on the separation and detection sensitivity was investigated. The reasonable resolutions between carboxylic acids were achieved using 1 mM PDCA eluent. Detection limits were 1.0-7.0 microM for conductivity detection and 8-30 microM for UV detection. Compared to the eluent containing 1 mM sulfuric acid, the method offers a high resolution and high detection sensitivity for both detectors due to its high molar absorptivity and low background conductance. The proposed method was demonstrated to be useful for the determination of carboxylic acids in environmental samples with direct sample injection. PMID:10574210

Chen, Z; Tang, C; Xu, J

1999-10-29

19

Matrix-elimination with steam distillation for determination of short-chain fatty acids in hypersaline waters from pre-salt layer by ion-exclusion chromatography.  

PubMed

A method for determination of formic, acetic, propionic and butyric acids in hypersaline waters by ion-exclusion chromatography (IEC), using steam distillation to eliminate matrix-interference, was developed. The steam distillation variables such as type of solution to collect the distillate, distillation time and volume of the 50% v/v H?SO? solution were optimized. The effect of the addition of NaCl different concentrations to the calibration standards on the carboxylic acid recovery was also investigated. Detection limits of 0.2, 0.5, 0.3 and 1.5 mg L?¹ were obtained for formic, acetic, propionic and butyric acids, respectively. Produced waters from petroleum reservoirs in the Brazilian pre-salt layer containing about 19% m/v of NaCl were analyzed. Good recoveries (99-108%) were obtained for all acids in spiked produced water samples. PMID:22226459

Ferreira, Fernanda N; Carneiro, Manuel C; Vaitsman, Delmo S; Pontes, Fernanda V M; Monteiro, Maria Inês C; Silva, Lílian Irene D da; Neto, Arnaldo Alcover

2011-12-14

20

Water quality monitoring system for determination of ionic nutrients by ion-exclusion chromatography with spectrophotometric detection on cation- and anion-exchange resin columns using water eluent.  

PubMed

A unified ion-exclusion chromatography (IEC) system for monitoring anionic and cationic nutrients like NH4+, NO2-, NO3-, phosphate ion, silicate ion and HCO3- was developed and applied to several environmental waters. The IEC system consisted of four IEC methodologies, including the IEC with ultraviolet (UV) form connected with detection at 210 nm for determining NH4+ on anion-exchange separation column in OH anion-exchange UV-conversion column in I- form in tandem, the IEC with UV-detection at 210 nm for determining simultaneously NO3- and NO3- on cation-exchange separation column in H+ form, the IEC with UV-detection at 210 nm for determining HCO3- on cation-exchange separation column in H+ form connected with anion-exchange UV-conversion column in I- form in tandem, and the IEC with visible-detection based on molybdenum-blue reaction for determining simultaneously silicate and phosphate ions on cation-exchange separation column in H+ form. These IEC systems were combined through three manually-driven 6-port column selection valves to select each separation column to determine selectively the ionic nutrients. Using this sequential water quality monitoring system, the analytical performances such as calibration linearity, reproducibility, detection limit and recovery were also tested under the optimized chromatographic conditions. This novel water quality monitoring system has been applied successfully for the determination of the ionic eutrophication components in sub-urban river waters. PMID:23189669

Kozaki, Daisuke; Nakatani, Nobutake; Mori, Masanobu; Nakagoshi, Nobukazu; Tanaka, Kazuhiko

2012-07-01

21

Selective and simultaneous determination of phosphate and silicate ions in leaching process waters for ceramics glaze raw materials of narutal origin by ion-exclusion chromatography coupled with UV-detection after postcolumn derivatization.  

PubMed

The selective and simultaneous ion-exclusion chromatography (IEC) with UV-detection on a weakly acidic cation-exchange resin column in the H+ -form (TSKgel Super IC-A/C) was developed and applied for the simultaneous determination of phosphate and silicate ions as the water quality parameters required for optimizing the water-leaching process for ceramics glaze raw materials of natural origin including feldspar, woods-ash, and straw-ash. Phosphate and silicate ions in these water-leaching process water samples were separated selectively from the coexisting anions such as sulfate, chloride, nitrate and carbonate ions, based on the ion-exclusion separation mechanism. They were detected selectively and simultaneously by a postcolumn derivatization with molybdenum-yellow using the UV-detector. Under the optimized separation and detection conditions (eluent, 0-1 mM sulfuric acid; reactant, 10 mM sodium molybdate-25 mM sulfuric acid; detector, UV at 370 nm; temperature, 45 degrees C), the linearity of calibration was in the range 0.1 - 10 ppm for both phosphate and silicate ions, and the detection limits at S/N = 3 were 2.58 ppb for silicate ions and 4.75 ppb for phosphate ions. The effectiveness of this method was demonstrated in practical applications to the water-leaching process for some ceramics glaze raw materials. PMID:16429785

Ikedo, Mikaru; Mori, Masanobu; Kurachi, Kazumasa; Hu, Wenzhi; Tanaka, Kazuhiko

2006-01-01

22

Liposome retention in size exclusion chromatography  

PubMed Central

Background Size exclusion chromatography is the method of choice for separating free from liposome-encapsulated molecules. However, if the column is not presaturated with lipids this type of chromatography causes a significant loss of lipid material. To date, the mechanism of lipid retention is poorly understood. It has been speculated that lipid binds to the column material or the entire liposome is entrapped inside the void. Results Here we show that intact liposomes and their contents are retained in the exclusion gel. Retention depends on the pore size, the smaller the pores, the higher the retention. Retained liposomes are not tightly fixed to the beads and are slowly released from the gels upon direct or inverted eluent flow, long washing steps or column repacking. Further addition of free liposomes leads to the elution of part of the gel-trapped liposomes, showing that the retention is transitory. Trapping reversibility should be related to a mechanism of partitioning of the liposomes between the stationary phase, water-swelled polymeric gel, and the mobile aqueous phase. Conclusion Retention of liposomes by size exclusion gels is a dynamic and reversible process, which should be accounted for to control lipid loss and sample contamination during chromatography.

Ruysschaert, Tristan; Marque, Audrey; Duteyrat, Jean-Luc; Lesieur, Sylviane; Winterhalter, Mathias; Fournier, Didier

2005-01-01

23

Immobilized metal ion affinity chromatography  

Microsoft Academic Search

This article describes the technique of immobilized metal ion affinity chromatography (1MAC). The IMAC stationary phases are\\u000a designed to chelate certain metal ions that have selectivity for specific groups in peptides and on protein surfaces. The\\u000a number of stationary phases that can be synthesized for efficient chclation of metal ions is unlimited, but the critical consideration\\u000a is that there is

Tai-Tung Yip; T. William Hutchens

1994-01-01

24

ION CHROMATOGRAPHY OF ANIONS  

EPA Science Inventory

A Dionex Model 10 Ion Chromatograph was evaluated for the measurement of anionic species in water. The theoretical effect of hydrogen ion activity (pH) on the elution time of phosphate and arsenate was tested and empirical selectivity coefficients were determined for the major pr...

25

Monolithic Phases for Ion Chromatography  

NASA Astrophysics Data System (ADS)

Monolithic media are continuing to increase in popularity in chromatographic applications, and the ongoing use of commercially available materials in ion chromatography (IC) has made monoliths a viable alternative to packed-bed columns for routine use. We discuss different strategies for the synthesis of polymeric and silica monoliths with ion-exchange functionality, such as direct incorporation of ion-exchange functionality during monolith preparation and different postpolymerization alterations such as grafting and coating. The formulations and strategies presented are focused on materials intended for use in IC. We also discuss strategies for materials characterization, with emphasis on nondestructive techniques for the characterization of monolith surface functionality, especially those with applicability to in situ analysis. Finally, we describe selected IC applications of polymeric and silica monoliths published from 2008 to 2010.

Nordborg, Anna; Hilder, Emily F.; Haddad, Paul R.

2011-07-01

26

The Fractionation of PGB sub x by Molecular Exclusion Chromatography.  

National Technical Information Service (NTIS)

Preparations of PGBx were separated into active and inactive fractions by molecular exclusion chromatography on Sephadex G-100 or G-150. The optimum pH for this separation was 7.2. Similar results were found with some other molecular exclusion type packin...

H. W. Shmukler S. F. Kwong E. Soffer M. G. Zawryt

1979-01-01

27

Using Ion Exchange Chromatography to Separate Proteins  

NSDL National Science Digital Library

This activity website, hosted by the National Health Museum Activities Exchange, explores protein purification using ion chromatography. Students will separate a positively charged lysozyme from a negatively charged albumin at a neutral pH using ion exchange chromatography. The site includes information for the teacher, instructions and follow-up questions for students, and a list of supplies.

Daugherty, Ellyn A.; Exchange, Access E.

28

Using Ion Exchange Chromatography to Separate Proteins  

NSDL National Science Digital Library

This activity website, hosted by the National Health Museum Activities Exchange, explores protein purification using ion chromatography. Students will separate a positively charged lysozyme from a negatively charged albumin at a neutral pH using ion exchange chromatography. The site includes information for the teacher, instructions and follow-up questions for students, and a list of supplies.

Daugherty, Ellyn A.

2010-02-02

29

Use of a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin column and propionic acid as an eluent in ion-exclusion/adsorption chromatography of aliphatic carboxylic acids and ethanol in food samples.  

PubMed

We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method. PMID:21558657

Mori, Masanobu; Hironaga, Takahiro; Kajiwara, Hiroe; Nakatani, Nobutake; Kozaki, Daisuke; Itabashi, Hideyuki; Tanaka, Kazuhiko

2011-01-01

30

Analysis of the acidic microenvironment in murine tumours by high-performance ion chromatography  

Microsoft Academic Search

High-performance ion chromatography (HPIC) has been utilised to probe the biochemistry associated with changes in tumour pH following total vascular occlusion. Samples from the tumour extracellular compartment were obtained by insertion of a microdialysis probe and analysed by HPIC with conductivity detection. Separations were carried out by ion-exclusion chromatography using an IonPac ICE AS1 weak-acid column. The eluent (0.5 mM

M. R. L. Stratford; C. S. Parkins; S. A. Everett; M. F. Dennis; M. Stubbs; S. A. Hill

1995-01-01

31

Polymer characterization by size-exclusion chromatography with multiple detection  

Microsoft Academic Search

Size-exclusion chromatography with coupled multiangle light scattering and differential refractometry detectors has been used to obtain molecular mass and radius of gyration distributions of polydisperse polymer samples. From these data the scaling law between dimensions and the absolute molecular mass is obtained with just one sample of each polymer. Three different kinds of polymers are presented: polystyrene which serves as

M. Teresa R. Laguna; Ricardo Medrano; Miguel P. Plana; M. Pilar Tarazona

2001-01-01

32

High-performance chelation ion chromatography  

Microsoft Academic Search

A review of so-called high-performance chelation ion chromatography (HPCIC) is presented. The principles of this separation technique are based on exploitation of the chelation effect of stationary phases in the presence of comparatively reduced electrostatic ion-exchange interactions. The common ways to suppress ion-exchange, including increasing the ionic strength and pH of the eluent and the column temperature, are discussed. Unlike

Phil Jones; Pavel N Nesterenko

1997-01-01

33

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

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

Using ion chromatography to monitor haloacetic acids in drinking water: a review of current technologies.  

PubMed

A review of the application of ion chromatography to the determination of haloacetic acids in drinking water is given. As it requires no sample derivatisation, ion chromatography in its various modes, such as ion-exchange, ion-interaction and ion-exclusion chromatography, is increasingly being investigated as a simpler alternative to gas chromatographic methods for the determination of polar disinfection by-products (DBPs) in drinking waters. Detection limits quoted for the regulated haloacetic acids (HAA5), are commonly in the mid to low microg/L range, however, in most cases analyte preconcentration is still necessary for detection at concentrations commonly found in actual drinking water samples. The coupling of ion chromatography to electrospray mass spectrometry provides a potential future direction, with improved sensitivity and selectivity compared to conductivity based detection, however associated cost and complexity for routine analysis is currently relatively high. PMID:15387163

Paull, Brett; Barron, Leon

2004-08-13

36

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

37

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

38

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

39

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

40

Resolution of quadruplex polymorphism by size-exclusion chromatography.  

PubMed

This unit describes a method for separation of quadruplex species formed from the same sequence via size-exclusion chromatography (SEC). Polymorphism is inherent to quadruplex formation, and even relatively simple quadruplex-forming sequences, such as the human telomere sequence d(GGG(TTAGGG)(3)), can form a myriad of possible configurations. HPLC, especially using reversed-phase and anion-exchange methods, has been a mainstay of nucleic acids research and purification for many decades. These methods have been applied for separation of individual quadruplex species formed in a mixture from the same parent sequence. PMID:21638270

Miller, M Clarke; Trent, John O

2011-06-01

41

Size-exclusion chromatography: smaller, faster, multi-detection, and multi-dimensions  

Microsoft Academic Search

Size-exclusion chromatography (SEC), also known as gelpermeation chromatography (GPC) or gel-filtration chromatography (GFC), is generally considered the premier method for determining the molar mass averages and distribution of polydisperse macromolecules. SEC is a liquid chromatography technique in which dissolved analyte is injected on to a column packed with porous, inert material. For samples with a distribution of analyte sizes the

André M. Striegel

2008-01-01

42

Size exclusion chromatography of aged and crumb rubber modified asphalts  

SciTech Connect

Preparative size exclusion chromatography (SEC) has been used for several years in our laboratory to provide samples for further analysis and for use in other testing procedures. Asphalts have been separated into a first fraction (F-I) that contains nonfluorescing (at 350 nm) materials, and the rest of the asphalt, which is collected in one or more fractions (F-II or F-IIa, F-IIb, etc). The nonfluorescing materials have been shown to contain strongly associating molecules, while the fluorescing materials consist of weakly associating individual and smaller molecules. The fractionation data from these analyses have been related to the theological property tan delta, and thereby, to rutting and premature pavement cracking. We have developed a high performance liquid chromatography (HPLC) technique that yields these analytical data more rapidly and efficiently than preparative SEC and yet gives chromatograms similar to those derived from preparative SEC. The HPLC procedure described here uses toluene as the carrier as does the preparative procedure.

Duvall, J.J. [Western Research Institute, Laramie, WY (United States)

1996-12-31

43

2-D chromatography with optimized size exclusion chromatography resolution and multi-angle light scattering coupling.  

PubMed

2-D chromatography has become an important tool for the polymer chemist and engineer interested in understanding reaction mechanisms in multiple step polymerization reactions and for establishing the relationships between structure and property. As with 1-D chromatography, it is desirable to obtain the best possible resolution in order to distinguish subtle differences in composition and molecular weight. This requirement is in conflict with the need to keep the duration of the experiment short enough for practical purposes. In this paper, we use a model system to investigate the optimum conditions for improved 2-D resolution with a focus on the molecular weight dimension. This dimension is usually the less resolved in 2-D systems due to synchronization requirements between the two separation processes and the subsequent need to use a rapid size exclusion chromatography column. The method described here provides resolution in the SEC dimension equivalent to that of a standard 1-D SEC method, while maintaining a relatively short analysis time. Finally, a multi-angle light scattering detector was used to determine the radius of gyration of the eluting polymer. PMID:20405486

Moyses, Stephan

2010-06-01

44

Ion Chromatography Analysis of Dibutyl Phosphoric Acid  

SciTech Connect

Analysis of dibutyl phosphate (DBP), a degradation product of tributyl phosphate (TBP), has long been a problem analysis by Ion Chromatography at the Savannah River Site. Due to the presence of UO{sub 2}{sup +2} and high NO{sub 3}{sup {minus}1} concentrations, inadequate recovery and separation of DBP on the chromatographic column had rendered the analysis undependable and very inconsistent, thus causing high uncertainties in the data. The method presented here by the Savannah River Technology Center (SRTC)/Analytical Development Section (ADS) addresses the sample preparation problems encountered when analyzing for DBP in the presence of uranium and nitrate. The data presented reflects the improvements made to decrease data uncertainty and increase data accuracy and precision.

Ray, R.J.

1998-12-04

45

Ni(II)-based immobilized metal ion affinity chromatography of recombinant human prolactin from periplasmic Escherichia coli extracts.  

PubMed

A novel, two-step preparative technique is described for the purification of authentic recombinant human prolactin (rhPRL) secreted into the periplasm of transformed Escherichia coli cells. The first step is based on immobilized metal ion affinity chromatography of periplasmic extract, using Ni(II) as a relatively specific ligand for hPRL in this system. It gives superior resolution and yield than established ion-exchange chromatography. Size-exclusion chromatography is used for further purification to >99.5% purity. The methodology is reproducible, leading to 77% recovery. Identity and purity of the rhPRL were demonstrated using sodium dodecylsulphate-polyacrylamide electrophoresis, isoelectric focusing, mass spectrometry (matrix-assisted laser desorption ionization time-of-flight), radioimmunoassay, RP-HPLC and high-performance size-exclusion chromatography. In the Nb2 bioassay, the hormone showed a bioactivity of 40.9 IU/mg. PMID:11486861

Ueda, E K; Gout, P W; Morganti, L

2001-07-13

46

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

47

Liquid Chromatography at Critical Conditions: Balancing size exclusion and adsorption in nanopores  

NASA Astrophysics Data System (ADS)

Liquid chromatography at critical condition (LCCC) is a measure to identify thermodynamic conditions, in which polymers elute independently of molar mass during high performance liquid chromatography. Under these critical conditions the entropic exclusions that dominate size exclusion chromatography (SEC) and the enthalpic adsorption that governs adsorption-based interaction chromatography (IC) are said to negate one another resulting in simultaneous elution of the polymer of different molecular weights. Using multiple C18-bonded silica columns with different average nanopore sizes (from 5 nm to 30 nm), we will study the LCCC conditions of PS in methylene chloride/acetonitrile solvent mixture at different temperature. In addition, we will show that the separation of polystyrene can be fine tuned using a refined temperature gradient interaction chromatography (TGIC) that employs multiple columns of varying pore size in sequence.

Abdulahad, Asem; Amos, Jeffrey; Ryu, Chang

2009-03-01

48

Determination of UV stabilizers in pet bottles by high performance?size exclusion chromatography  

Microsoft Academic Search

A Size Exclusion Chromatography?High Performance Liquid Chromatography (SEC?HPLC) method to determine antioxidants and UV stabilizers in PET bottles has been developed. In only a single run a synthetic mixture of the stabilizers was separated and quantified. The detection limit obtained for BHT, Tinuvin 326, Cyasorb UV 5411, and Tinuvin P was about 0.1 ?g\\/g and for Irgafos 168 it was

M. Monteiro; C. Nerín; F. G. R. Reyes

1996-01-01

49

Recent progress in carbohydrate separation by high-performance liquid chromatography based on size exclusion  

Microsoft Academic Search

Since the introduction of stationary phases based on microparticulate porous silica and polymeric sorbents, rigid and semi-rigid, size-exclusion chromatography (SEC) has become established as a form of high-performance liquid chromatography. In recent years, there have beeen revolutionary developments in detection systems for high-performance SEC, which have placed the use of the method for the determination of molecular-size and molecular-weight distributions

Shirley C Churms

1996-01-01

50

Practical experience with on-line ion chromatography  

SciTech Connect

Bettis is heavily involved in on-line ion chromatography and has gained much experience with the systems. This paper serves to pass that experience along to any users, current or prospective, that are interested in the systems. On-line IC is extremely dynamic and the developments over the past few years have helped to produce systems that can provide technical and productivity improvements. The potential uses of the systems are only beginning to be tapped. It is the information provided herein maybe useful to any interested in on-line ion chromatography.

Lynch, G.J.

1991-12-31

51

Concentration effect in hyaluronan analysis by size exclusion chromatography  

Microsoft Academic Search

The concentration effect in size-exclusion chromatographic analysis of hyaluronans of various relative molecular masses (RMM) has been studied. A critical concentration has been found that is negatively dependent on the hyaluronan molecular mass; the higher the biopolymer molecular mass, the smaller the injected sample where the concentration effect should be taken into account for accurate evaluation of molecular mass distribution.

E. Orviský; L. Šoltés; S. Al Assaf

1994-01-01

52

Determination of the molecular mass and dimensions of membrane proteins by size exclusion chromatography  

Microsoft Academic Search

Size exclusion chromatography is an established technique for the determination of hydrodynamic volumes of proteins or protein complexes. When applied to membrane proteins, the contribution of the detergent micelle, which is required to keep the protein soluble in the aqueous phase, needs to be determined to obtain accurate measurements for the protein. In a detergent series, in which the detergents

Edmund R. S. Kunji; Marilyn Harding; P. Jonathan G. Butler; Pearl Akamine

2008-01-01

53

Size-exclusion chromatography of lignin- and carbohydrate-containing samples using alkaline eluents  

Microsoft Academic Search

Size-exclusion chromatography of carbohydrate- and lignin-containing samples, prepared from wood and pulp samples, was carried out using alkaline eluents. The elution of carbohydrate and lignin macromolecules can be monitored with good selectivity using a pulsed amperometric and a UV absorbance detector, respectively. However, the stability of the signals from samples stored in alkaline solutions requires careful consideration in the analysis

Ken K. Y. Wong; Ed de Jong

1996-01-01

54

Size exclusion chromatography (XII). Analysis of silicon-phenyl groups in molecular weight components of polydimethylsiloxanes  

Microsoft Academic Search

Methods for the qualitative and quantitative determination of silicon-phenyl groups in molecular weight components of silicones of the Sylgard type (polydimethylsiloxanes (PDMS)) were developed. On-line size exclusion chromatography was used with differential refractometer (DR), infrared (ir) and ultraviolet (uv) detection, at 254 and 215 nm. For the qualitative analyses the mobile phase was methylene chloride, with uv detection at 254

1986-01-01

55

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

56

Stability of tumor necrosis factor-? during ion exchange chromatography  

Microsoft Academic Search

Denaturation of target protein by various separation and purification steps contributes significant part to the total product loss in bioseparation. The conformational change and accompanying loss of activity of tumor necrosis factor-a during ion exchange chromatography was reversible and was decreased by adding polyethylene glycol 200 at 2 to 5% (v\\/v) to the eluting solution.

Ming Li; Yunshan Wang; Weijun Li; Zhiguo Su

2003-01-01

57

Forensic Identification of Inorganic Explosives by Ion Chromatography  

Microsoft Academic Search

While there is a great deal of published literature describing methods for the analysis of organic explosives by various methods, there are comparatively few publications concerning the analysis of explosives based on inorganic chemicals. This mini?review examines the literature that is concerned with the analysis of such explosives, commonly referred to as improvised explosive devices, using ion chromatography. Pertinent details

Greg W. Dicinoski; Robert A. Shellie; Paul R. Haddad

2006-01-01

58

Wirkstoffnachweis in Haaren mit Gas chromatographie - Ion Trap-Massen  

Microsoft Academic Search

The aim of this paper is to investigate the suitability of Gas Chromatography - Ion Trap - Mass Spectrometry for the detection not only of 'classic' groups of addictive drugs but also of legal drugs in hair. Amphetamines and Tetrahydrocannabinol (+CBD, CBN) were extracted by 1- chlorobutane after alkaline hydrolysis of the hair. The amphetamines were re-extracted by weak acid,

Ulrich Demme; Otto Wallbraun

59

[Purification of immunoglobulin and serum albumin from serum via strong anion exchange chromatography coupled with molecular exclusion chromatography].  

PubMed

The isoelectric points of immunoglobulin (Ig) and serum albumin (SA) in animal serum are about 7.8 and 4.8, respectively. Based on their larger difference of isoelectric points, Q Sepharose-XL strong anion exchange chromatography coupled with molecular exclusion chromatography was used to purify Ig and SA simultaneously from the high immune rabbit serum. After the Q Sepharose-XL strong anion exchange column was equilibrated with 0.02 mol/L Tris-HCl buffer of pH 8.0, a 10-fold dilution sample of rabbit serum was loaded onto the column and the pH gradient elution was performed. With the low flow rate of elution of 0.3 mL/min, the high-purity Ig was obtained when the elution pH was at 6.0. Continuously eluted at pH 4.0 with the same flow rate of elution, the SA was obtained and its purity was greater than 95% after molecular exclusion chromatography through Sephadex G-75. The purified Ig and SA were demonstrated to maintain normal activities by activity analysis. The results of protein content showed that the purification recoveries of Ig and SA were over 95% and 90%, respectively. The method has the advantages of simple operation and rapidity, and the Ig and SA purified simultaneously from the animal serum could maintain normal activities. PMID:23256392

Qin, Zonghua; Chen, Ting; Li, Renqiang

2012-08-01

60

Molecular mass ranges of coal tar pitch fractions by mass spectrometry and size-exclusion chromatography.  

PubMed

A coal tar pitch was fractionated by solvent solubility into heptane-solubles, heptane-insoluble/toluene-solubles (asphaltenes), and toluene-insolubles (preasphaltenes). The aim of the work was to compare the mass ranges of the different fractions by several different techniques. Thermogravimetric analysis, size-exclusion chromatography (SEC) and UV-fluorescence spectroscopy showed distinct differences between the three fractions in terms of volatility, molecular size ranges and the aromatic chromophore sizes present. The mass spectrometric methods used were gas chromatography/mass spectrometry (GC/MS), pyrolysis/GC/MS, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) and laser desorption time-of-flight mass spectrometry (LD-TOFMS). The first three techniques gave good mass spectra only for the heptane-soluble fraction. Only LDMS gave signals from the toluene-insolubles, indicating that the molecules were too involatile for GC and too complex to pyrolyze into small molecules during pyrolysis/GC/MS. ESI-FTICRMS gave no signal for toluene-insolubles probably because the fraction was insoluble in the methanol or acetonitrile, water and formic acid mixture used as solvent to the ESI source. LDMS was able to generate ions from each of the fractions. Fractionation of complex samples is necessary to separate smaller molecules to allow the use of higher laser fluences for the larger molecules and suppress the formation of ionized molecular clusters. The upper mass limit of the pitch was determined as between 5000 and 10,000 u. The pitch asphaltenes showed a peak of maximum intensity in the LDMS spectra at around m/z 400, in broad agreement with the estimate from SEC. The mass ranges of the toluene-insoluble fraction found by LDMS and SEC (400-10,000 u with maximum intensity around 2000 u by LDMS and 100-9320 u with maximum intensity around 740 u by SEC) are higher than those for the asphaltene fraction (200-4000 u with maximum intensity around 400 u by LDMS and 100-2680 u with maximum intensity around 286 u by SEC) and greater than values considered appropriate for petroleum asphaltenes (300-1200 u with maximum intensity near 700 u). PMID:19489019

Karaca, F; Morgan, T J; George, A; Bull, I D; Herod, A A; Millan, M; Kandiyoti, R

2009-07-01

61

Ion chromatography of cations using indirect photometric of fluorometric detection  

SciTech Connect

Copper(II) and cerium(III) were compared as mobile phase counter-ions with a strong cation exchange column for indirect photometric chromatography (IPC). Sample ion retention time was found to be dependent upon both counter-ion size and charge, as well as mobile phase ionic strength. Detection limits of all sample ions were found to be highly dependent on the molar absorptivity of the counter-ion at the wavelength of detection. At 254nm, a cerium(III) mobile phase provided detection limits at least 100 times lower than did a copper(II) mobile phase. The detection limit of sodium was about 4 ppb, corresponding to 3.5 pmoles, using a Ce(III) mobile phase. Cerium(III) was used as a mobile phase counter-ion with a strong cation exchange column using indirect fluorescence detection. Separation of the alkali metal ions along with the ammonium ion was achieved with baseline resolution. The detection limit of sodium was 3 ppb, corresponding to 2.6 pmoles. Separation and quantitation of sodium, ammonium, and potassium ions in diluted urine was straightforward. In contrast, using indirect UV detection, interference from the sample matrix was a problem. IPC using a cerium(III) mobile phase was used to determine sodium, potassium, magnesium, and calcium ions in milk and infant formulas. Separation was complete within 17 minutes. No interference from the sample matrix was noted. Good agreement between the IPC results and atomic absorption spectroscopy was found. Several complexes of chromium(III) were studied as mobile phase candidates for indirect photometric chromatography. A complex of tris(bipyridine)chromium(III) possessed the required spectral properties of an IPC counterion, but proved to be somewhat labile in either water or methanol but not acetonitrile.

Sherman, J.H.

1987-01-01

62

Ion exclusion by sub-2-nm carbon nanotube pores  

PubMed Central

Biological pores regulate the cellular traffic of a large variety of solutes, often with high selectivity and fast flow rates. These pores share several common structural features: the inner surface of the pore is frequently lined with hydrophobic residues, and the selectivity filter regions often contain charged functional groups. Hydrophobic, narrow-diameter carbon nanotubes can provide a simplified model of membrane channels by reproducing these critical features in a simpler and more robust platform. Previous studies demonstrated that carbon nanotube pores can support a water flux comparable to natural aquaporin channels. Here, we investigate ion transport through these pores using a sub-2-nm, aligned carbon nanotube membrane nanofluidic platform. To mimic the charged groups at the selectivity region, we introduce negatively charged groups at the opening of the carbon nanotubes by plasma treatment. Pressure-driven filtration experiments, coupled with capillary electrophoresis analysis of the permeate and feed, are used to quantify ion exclusion in these membranes as a function of solution ionic strength, pH, and ion valence. We show that carbon nanotube membranes exhibit significant ion exclusion that can be as high as 98% under certain conditions. Our results strongly support a Donnan-type rejection mechanism, dominated by electrostatic interactions between fixed membrane charges and mobile ions, whereas steric and hydrodynamic effects appear to be less important.

Fornasiero, Francesco; Park, Hyung Gyu; Holt, Jason K.; Stadermann, Michael; Grigoropoulos, Costas P.; Noy, Aleksandr; Bakajin, Olgica

2008-01-01

63

Size-exclusion chromatography of technical lignins in dimethyl sulfoxide\\/water and dimethylacetamide  

Microsoft Academic Search

Well defined spent sulfite liquor samples and lignosulfonate fractions obtained by ultrafiltration were analyzed using size-exclusion chromatography. Two different eluent systems (dimethyl sulfoxide\\/water\\/lithium bromide; dimethylacetamide\\/lithium chloride) were compared regarding their suitability for lignin analysis. The differences of the elution profiles and calculated molar masses were discussed using conventional and universal calibration. For further validation four technical lignins from a Round

Okko Ringena; Sascha Lebioda; Ralph Lehnen; Bodo Saake

2006-01-01

64

ANALYSIS OF RESIDUUM DEMETALATION BY SIZE EXCLUSION CHROMATOGRAPHY WITH ELEMENT SPECIFIC DETECTION  

Microsoft Academic Search

We analyzed thermally treated heavy residua by element specific size exclusion chromatography (SEC-ICF) to elucidate the fate of the V and Ni compounds. Thermal treatment, in addition to removing metals, significantly reduces the size of the remaining metal-containing compounds.We thermally treated the distillable and nondistillable metals separately. The distilled metals, primarily petroporphyrins, were completely removed under moderate conditions. The non-volatile

John G. Reynolds; Wilton R. Biggs

1986-01-01

65

Size-exclusion chromatography of low-molecular-mass polymers using mesoporous silica  

Microsoft Academic Search

In this study, the mesoporous silicas APMS-30 and MCM-41 were compared to a commercial silica, Nucleosil, in size-exclusion chromatography (SEC). Polystyrenes of various molecular masses (M) were passed through HPLC columns of the silicas (each column contained a single type of silica) and retention times were plotted as a function of logM for each type of silica. Linear fits to

Terry Nassivera; Andrew G. Eklund; Christopher C. Landry

2002-01-01

66

Continuous spin fractionation and characterization by size-exclusion chromatography for styrene–butadiene block copolymers  

Microsoft Academic Search

Linear and star-shaped styrene–butadiene block copolymers synthesized by anionic polymerization of butadiene and styrene were fractionated by applying a newly developed large-scale fractionation technique, named continuous spin fractionation (CSF). Their molecular weight and polydispersity index (d=Mw\\/Mn) were measured with size-exclusion chromatography and static light scattering. For the linear triblock copolymer a fractionation via temperature variation turned out to be better

Xiaopeng Xiong; John Eckelt; Bernhard A. Wolf; Zhengjun Zhang; Lina Zhang

2006-01-01

67

Determination of some pesticides and intermediates by ion chromatography  

Microsoft Academic Search

We explored the possibility of determining some pesticides and process intermediates by ion chromatography. Some applications of this technique, standardized and adopted to meet the requirements of Gharda Chemicals (which is a leading producer of agrochemicals in India), will be presented in this communication. These include analysis of the finished products [(a) dicamba dimethylamine (DMA)\\/potassium\\/sodium salt acid and (b) 2,4-dichlorophenoxyacetic

N. D Gangal; S. S Bondre; P. S Ramanathan

2000-01-01

68

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

69

Determination of metal ions by ion chromatography with precolumn electrochemical preconcentration  

Microsoft Academic Search

The determination of heavy metals in concentrations less than 10-6 mol\\/L by ion chromatography with conductivity detection requires a preconcentration step. Therefore, a special electrochemical equipment and method was developed for the on-line preconcentration of the divalent metals Ni, Co, Zn and Cd and their subsequent ion chromatographic determination. The loop of the injection valve of an ion chromatograph was

Frank Hißner; Jürgen Mattusch; G. Werner

1996-01-01

70

Electrospray-differential mobility analysis as an orthogonal tool to size-exclusion chromatography for characterization of protein aggregates.  

PubMed

The biopharmaceutical industry characterizes and quantifies aggregation of protein therapeutics using multiple analytical techniques to cross-validate results. Here, we demonstrate the use of electrospray-differential mobility analysis (ES-DMA), a gas-phase and atmospheric pressure ion-mobility method for characterizing protein aggregates. Two immunoglobulin Gs are systematically heat treated to induce aggregation and characterized using size-exclusion chromatography (SEC) and ES-DMA. Although ES-DMA is a gas-phase characterization method, we find that aggregation kinetic rate constants determined by ES-DMA is in good agreement with those determined by SEC. ES-DMA appears to have a higher resolution and lower limit of detection as compared with SEC. Thus, ES-DMA can potentially become an important orthogonal tool for characterization of nascent protein aggregates in the biopharmaceutical industry. PMID:22411567

Guha, Suvajyoti; Wayment, Joshua R; Tarlov, Michael J; Zachariah, Michael R

2012-03-12

71

Chelation ion chromatography of trace metal ions using metallochromic ligands  

Microsoft Academic Search

Hydrophobic metallochromic ligands can be used to coat high-performance reversed-phase substrates producing chelating stationary phases with the capacity to separate metal ions. To date the main approaches have been to `pre-coat' the substrate with the ligand and use it with a mobile phase containing an inorganic salt or alternatively to include the ligand itself within the mobile phase, where the

Paul R Haddad

1999-01-01

72

[Determination of iodide, thiocyanate and perchlorate ions in environmental water by two-dimensional ion chromatography].  

PubMed

A procedure for the determination of iodide, thiocyanate and perchlorate ions in environmental water by two-dimensional ion chromatography has been developed. At first the iodide, thiocyanate and perchlorate ions were separated from interfering ions by a column (IonPac AS16, 250 mm x 4 mm). The iodide ion, thiocyanate and perchlorate ions were then enriched with an enrichment column (MAC-200, 80 mm x 0.75 mm). In the 2nd-dimensional chromatography, iodide thiocyanate and perchlorate ions were separated and quantified by a capillary column (IonPac AS20 Capillary, 250 mm x 0.4 mm). The linear ranges were 0.05 -100 pg/L with correlation coefficients of 0. 999 9, and the detection limits were 0. 02 - 0.05 micro gg/L. The spiked recoveries of iodide, thiocyanate and perchlorate ions were in the range of 85.1% to 100.1%. The relative standard deviations of the recoveries were 1.7% to 4.9%. PMID:23786003

Lin, Li; Wang, Haibo; Shi, Yali

2013-03-01

73

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

74

[Studies on formation of aggregates from denatured lysozymes upon renaturing with size exclusion chromatography].  

PubMed

In order to study the renaturation mechanism of denatured protein in denaturant solution, the renaturation and separation process for three kinds of lysozyme molecules, which were separately denatured by urea and guanidine hydrochloride in the presence of reducing agents, was studied by size exclusion chromatography. When initial lysozyme concentration in denaturant solution was more than 10 g/L, the denatured lysozyme molecules were renatured and isolated in a size exclusion chromatographic column. A refolded lysozyme intermediate, a bi-molecular aggregate, was found. This result was confirmed by non-reducing sodium dodecyl sulfate-polyacrylamide gel electrohoresis (SDS-PAGE) analysis of renatured lysozyme molecules with the dilution method. Compared with the dilution method, the amount of the bi-molecular aggregate found by size exclusion chromatography was far less than that found in the dilution method. This result shows that the process for the renaturing of denatured lysozyme molecules in solution can be well described with three-state model in the presence of reducing agents. PMID:16013553

Bian, Liujiao; Yang, Xiaoyan; Liu, Li

2005-03-01

75

[Study on protein separation using immobilized metal ion affinity chromatography].  

PubMed

Immobilized metal ion affinity chromatography (IMAC) has shown promise of isolating desired proteins from a mixture based on their difference of affinity for chelated metal ions. With its technological superiority, such as large adsorption capacity, mild separation condition, simple ligands and wide applications, IMAC has become powerful tool for biotechnological products separation, such as proteins, amino acids and gene products. In spite of many sophisticated applications for IMAC, the theoretical analysis of Immobilized metal chromatography has remained insufficient. In this paper, the eluted efficiencies of bovine serum albumin (BSA) in a single-component system under different elution conditions are studied. The effects of several elution factors, such as pH value, ammonium concentration and anion species on protein separation are studied. Comparing the elution data of BSA in IDA-Cu and IDA-Zn columns, the different ability of affinity between metal ions and proteins is found. In addition, the elution behaviors of different proteins are investigated. This work facilitates the further research in separation of real systems. PMID:11051827

Sun, X D; Li, H Q; Sui, H Y; Shen, Z Y

2000-07-01

76

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

77

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. Unlike other chemical quantification techniques, IC provides results on ions not expected in the production solutions. Thus, solution contamination and break-down products can be monitored in every phase of the circuit board manufacturing. During the first phase, epoxy laminates experience an etchback, first in chromic acid, which can be analyzed for trace chloride and sulfate, then in ammonium bifluoride/HCl, which can be analyzed for fluoride and chloride. Following a wet-blasting to roughen up the surface, 20 microinches of copper are deposited using an electroless bath. Again, IC is applicable for monitoring formate, tartarate, and sulfate levels. Next, an acid copper bath is used to electroplate the through holes with 0.001 inches of ductile copper. This bath is analyzed for trace chloride. Photoimaging is then performed, and the organic solvents used can be assayed for trace ionic chloride. Finally, a fluoroboric acid-based tin-lead bath is used to deposit a solderable alloy. This bath is analyzed for fluoroborate, tin, and lead. In addition, mobile phase ion chromatography (MPIC) is used to monitor the nonionic organic brighteners in the baths. 11 refs., 7 figs.

Smith, R.E.

1990-01-01

78

A novel amide stationary phase for hydrophilic interaction liquid chromatography and ion chromatography.  

PubMed

A novel amide stationary phase (ASP) for hydrophilic interaction liquid chromatography (HILIC) has been prepared via the Click chemistry method. It was based on the strategy that the amino group of Asparagine was easily transferred to the corresponding azido group and then clicked onto terminal alkyne-silica gel in the presence of Cu(I)-based catalyst. For the tested polar compounds including nucleosides and nucleic acid bases, ASP-based column has demonstrated good performance in terms of separation efficiency and column stability, and the retention mechanism was found to match well the typical HILIC retention. In addition, the ASP described here showed much better selectivity in separation of inorganic anions under ion chromatography mode relative to other kinds of commercial ASP. PMID:24054569

Shen, Guobin; Zhang, Feifang; Yang, Bingcheng; Chu, Changhu; Liang, Xinmiao

2013-04-28

79

Using size exclusion chromatography-RPLC and RPLC-CIEF as two-dimensional separation strategies for protein profiling  

SciTech Connect

Bottom-up proteomics (analyzing peptides that result from protein digestion) has demonstrated capability for broad proteome coverage and good throughput. However, due to incomplete sequence coverage, this approach is not ideally suited to the study of modified proteins. The modification complement of a protein can best be elucidated by analyzing the intact protein. Two-dimensional gel electrophoresis, typically coupled with the analysis of peptides that result from in-gel digestion, is the most frequently applied protein separation technique in MS-based proteomics. As an alternative, numerous column-based liquid phase techniques, which are generally more amenable to automation, are being investigated. In this work, the combination of size exclusion chromatography (SEC) fractionation with reversed-phase liquid chromatography (RPLC)-Fourier-transform ion cyclotron resonance (FTICR)-mass spectrometry (MS) is compared with the combination of RPLC fractionation with capillary isoelectric focusing (CIEF)-FTICR-MS for the analysis of the Shewanella oneidensis proteome. SEC-RPLC-FTICR-MS allowed the detection of 297 proteins, as opposed to 166 using RPLC-CIEF-FTICR-MS, indicating that approaches based on LC-MS provide better coverage. However, there were significant differences in the sets of proteins detected and both approaches provide a basis for accurately quantifying changes in protein and modified protein abundances.

Simson, David C.; Ahn, Seonghee; Pasa-Tolic, Liljiana; Bogdanov, Bogdan; Brewer, Heather M.; Vilkov, Andrey N.; Anderson, Gordon A.; Lipton, Mary S.; Smith, Richard D.

2006-07-01

80

Fractionation by planar chromatography of a coal tar pitch for characterisation by size-exclusion chromatography, UV fluorescence and direct-probe mass spectrometry  

Microsoft Academic Search

A coal tar pitch, extensively studied by other techniques, has been fractionated by planar chromatography using successive development in tetrahydrofuran, chloroform-methanol (4:1, v\\/v), toluene and pentane. Pitch fractions were distinguished by relative retention. The fractions were characterised in solution by size-exclusion chromatography, UV-fluorescence emission spectroscopy and as the solid on silica, by direct solid-probe mass spectrometry. The method has led

Alan A. Herod; Rafael Kandiyoti

1995-01-01

81

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

82

The obstruction factor in size-exclusion chromatography. 1. The intraparticle obstruction factor.  

PubMed

We report the first of a series of studies on the obstruction factor ? in size-exclusion chromatography (SEC). Here, using narrow dispersity polymer standards we examine how the intraparticle obstruction factor ?(p) depends individually on a number of analyte properties, column characteristics, and user-defined parameters. Far from being constant, ?(p) is seen to vary with analyte molar mass and solvent, as well as with the pore size and particle size of the column packing material, sometimes in seemingly counterintuitive manner. Over the limited temperature range accessible to our equipment, however, no statistically significant change in ?(p) with temperature was discovered. The results presented should be applicable to forms of packed column chromatography other than SEC. The latter technique, however, presents a convenient test bed for quantitative determination of the obstruction factor, due to minimized sorptive mass transfer and longitudinal diffusion contributions to band broadening in most forms of SEC. PMID:20926085

Richard, Dustin J; Striegel, André M

2010-09-17

83

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

84

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

85

Improved reproducibility in the determination of the molecular weight of chitosan by analytical size exclusion chromatography  

Microsoft Academic Search

The reproducibility of the determination of the molecular weight of chitosans in the 90–210kDa range (Mn) by analytical size exclusion chromatography with multi-angle laser light scattering (SEC-MALLS) was improved by reducing the salt concentration in the mobile phase from (0.3M acetic acid, 0.2M sodium acetate, and 0.8mM sodium azide) to (0.15M acetic acid, 0.1M sodium acetate, and 0.4mM sodium azide)

Sophie Nguyen; Françoise M. Winnik; Michael D. Buschmann

2009-01-01

86

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

PubMed

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 not show the excessive retention observed with commercial polystyrene columns for polycyclic aromatic compounds. Therefore, a close correlation between the elution volume and M, for polycyclic aromatic compounds was observed with polybutadiene microbeads columns. PMID:16035360

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

2005-08-01

87

Determination of some pesticides and intermediates by ion chromatography.  

PubMed

We explored the possibility of determining some pesticides and process intermediates by ion chromatography. Some applications of this technique, standardized and adopted to meet the requirements of Gharda Chemicals (which is a leading producer of agrochemicals in India), will be presented in this communication. These include analysis of the finished products [(a) dicamba dimethylamine (DMA)/potassium/sodium salt acid and (b) 2,4-dichlorophenoxyacetic acid (2,4-D)], and the process intermediates [(c) tetrachlorobutyric acid and (d) glyoxylic acid/glycollic acid/formic acid]. Ion chromatographic analysis of sub-ppm levels of 2,5-dibromo- and monochlorobromo-phenols, in 2,5-dichlorophenol, after adequate sample preparation steps, is also being presented. PMID:10917443

Gangal, N D; Bondre, S S; Ramanathan, P S

2000-07-01

88

Ion chromatography detection of fluoride in calcium carbonate.  

PubMed

Fluoride in aquatic systems is increasing due to anthropogenic pollution, but little is known about how this fluoride affects organisms that live in and around aquatic habitats. Fluoride can bioaccumulate in structures comprised of calcium carbonate, such as shells and skeletons of both freshwater and saltwater species as diverse as snails, corals, and coccolithophorid algae. In this article, ion chromatography (IC) techniques are developed to detect and quantify fluoride in a matrix of calcium carbonate. Solid samples are dissolved in hydrochloric acid, pretreated to remove the majority of the chloride ions, and then analyzed using IC. With these methods, the 3? limit of detection is 0.2 mg of fluoride/kg of calcium carbonate. PMID:21859530

Lefler, Jamie E; Ivey, Michelle M

2011-09-01

89

The History of Ion Chromatography: The Engineering Perspective  

NASA Astrophysics Data System (ADS)

There is no question that the field of analytical chemistry has had a profound beneficial effect on society during the 19th and 20th centuries. The painstaking and often painfully frustrating work by analytical chemists is the stuff of which Nobel Prizes are made. Nonetheless, the engineering community must often remind these highly dedicated researchers that the original invention is frequently only the tip of the iceberg on the road from origin to commercialization. This article traces the history of the engineering development related to the several generations of ion chromatography instruments, columns, suppressers, and software. In so doing, several representative engineering challenges and their outcomes are discussed including: early directions (traveling without a road map, or "going where the applications are"), dealing with an extremely corrosive mobile phase (aka: the "eluent"), resolving the inherent incompatibilities of nonmetallic flow paths with the benefits of high-pressure, elevated temperature operation, managing the ever-evolving nature of the suppressor, coping with requirements for ultra high-end online systems, and providing extremely simple-to-use dedicated analyzer systems. Of particular note are stories of "reinventing for the first time" practices common to HPLC at that time but for which there was little or no experience with respect to challenges unique to ion chromatography.

Evans, Barton

2004-09-01

90

The use of liquid chromatography for the analysis of metal ions in aqueous solutions and for the determination of water in organic matrices  

SciTech Connect

The value of a p-phenylenediammonium eluent in single-column ion chromatography is demonstrated. It is shown to be particularly useful for separating trivalent aluminum from common divalent metal ion interferences. The aluminum is detected with a conductivity detector. Postcolumn reaction in liquid chromatography is reviewed. The application of disodium 1-(2-thiazolylazo)-2-naphthol-3,6-disulfonate (TAN-3,6-S) to the detection of metal ions in single-column ion chromatography with a visible absorbance detector is explored. Temperature is shown to affect the retention times of divalent and trivalent metal ions in ion chromatography. Several chromatographic separations are improved by operating the system at elevated temperature. Two methods for the determination of water in organic matrices using liquid chromatography and a spectrophotometric detector are presented. Both employ a chromatographic separation by ion-exclusion. The first detection method makes use of solvatochromism, the shift in an organic spectrum which occurs as solvent polarity is changed. The second detection method uses a solid-phase postcolumn reactor containing a cation-exchange resin in the H/sup +/ form. This reactor acts as catalyst for a reaction occurring between water and two components of the mobile phase, methanol and trans-cinnamaldehyde. 122 refs., 40 figs., 16 tabs.

Fortier, N.E.

1988-07-01

91

Ion Exclusion by Sub 2-nm Carbon Nanotube Pores  

SciTech Connect

Carbon nanotubes offer an outstanding platform for studying molecular transport at nanoscale, and have become promising materials for nanofluidics and membrane technology due to their unique combination of physical, chemical, mechanical, and electronic properties. In particular, both simulations and experiments have proved that fluid flow through carbon nanotubes of nanometer size diameter is exceptionally fast compared to what continuum hydrodynamic theories would predict when applied on this length scale, and also, compared to conventional membranes with pores of similar size, such as zeolites. For a variety of applications such as separation technology, molecular sensing, drug delivery, and biomimetics, selectivity is required together with fast flow. In particular, for water desalination, coupling the enhancement of the water flux with selective ion transport could drastically reduce the cost of brackish and seawater desalting. In this work, we study the ion selectivity of membranes made of aligned double-walled carbon nanotubes with sub-2 nm diameter. Negatively charged groups are introduced at the opening of the carbon nanotubes by oxygen plasma treatment. Reverse osmosis experiments coupled with capillary electrophoresis analysis of permeate and feed show significant anion and cation rejection. Ion exclusion declines by increasing ionic strength (concentration) of the feed and by lowering solution pH; also, the highest rejection is observed for the A{sub m}{sup Z{sub A}} C{sub n}{sup Z{sub C}} salts (A=anion, C=cation, z= valence) with the greatest Z{sub A}/Z{sub C} ratio. Our results strongly support a Donnan-type rejection mechanism, dominated by electrostatic interactions between fixed membrane charges and mobile ions, while steric and hydrodynamic effects appear to be less important. Comparison with commercial nanofiltration membranes for water softening reveals that our carbon nanotube membranes provides far superior water fluxes for similar ion rejection capabilities.

Fornasiero, F; Park, H G; Holt, J K; Stadermann, M; Grigoropoulos, C P; Noy, A; Bakajin, O

2008-04-09

92

Determination of Organobromide Compounds in Water by Gas Chromatography-Negative Ion Chemical Ionisation Mass Spectrometry.  

National Technical Information Service (NTIS)

Gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCIMS) was evaluated as a method for qualitative and quantitative determination of organobromine compounds in water. The negative ion mass spectra of bromine-containing trihalometha...

K. Koida Y. Kohno Y. Fukuda K. Sekigawa S. Yoshizaki

1985-01-01

93

Molecular Mass Characterization of Glycosaminoglycans with Different Degrees of Sulfation in Bioengineered Heparin Process by Size Exclusion Chromatography  

PubMed Central

Different degrees of glycosaminoglycan sulfation result in their different charge densities. The charge density differences impact their migration behavior in polyacrylamide gel electrophoresis and size exclusion chromatography, two of the most common methods for determining relative molecular masses of polysaccharides. In this study, we investigated the feasibility of using commercially available heparin oligosaccharides as calibrants for measuring the relative molecular masses of intermediates in a bioengineered heparin process that have different levels of sulfation. A size exclusion chromatography method was established that eliminates this charge density effect and allows the determination of relative molecular mass using a single calibration curve with heparin oligosaccharides calibrants. This is accomplished by overcoming the electrostatic interaction between the glycosaminoglycans and size exclusion chromatography stationary phase using high ionic strength mobile phase.

Wang, Zhenyu; Zhang, Fuming; Dordick, Jonathan S.; Linhardt, Robert J.

2012-01-01

94

Size exclusion chromatography (XIII): Identification and quantitation of silicon hydride containing oligomeric components of Sylgard prepolymers. [Polydimethylsiloxane  

Microsoft Academic Search

Methods for the identification and quantitation of oligomeric, silicon hydride (SiH), containing components of Sylgard prepolymers (polydimethylsiloxane: PDMS) have been developed. They employ a combination of size exclusion chromatography (SEC), with infrared (ir) and differential refractometer (DR) detection and gas chromatography\\/mass spectrometry (GC\\/MS) verification. The identified oligomers were present at about 20% of total prepolymer and contained from one to

E. Kohn; M. E. Chisum; K. L. Moore

1987-01-01

95

Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography  

PubMed Central

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 charged 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 composition but different sequence.

2010-01-01

96

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

97

Ultra-short columns for low-pressure ion chromatography.  

PubMed

Since the development of low-pressure ion chromatography (LPIC), many inorganic cations and anions as well as organic acids could be analyzed at a low-pressure of 1.96 x 10(5)-2.94 x 10(5) Pa. And the ultra-short columns took the place of the common long chromatographic columns. Furthermore, the ultra-short columns of LPIC not only reduced the system pressure appreciably, but also achieved high sensitivity and precision. In order to assess the characteristics of the super-short columns, much analysis, i.e., the analysis of alkali metals, alkaline earth metals, transition-metals, rare-earth elements, inorganic anions and organic acids as well as the common amino acids, were conducted. Moreover, excellent results were obtained from the LPIC columns. PMID:10536836

Jiang, X; Zhang, X; Liu, M

1999-10-01

98

A phosphate binding assay for sevelamer hydrochloride by ion chromatography.  

PubMed

Sevelamer hydrochloride is a cross-linked polymeric amine; it is the active ingredient of Renagel capsules. Renagel is indicated for the control of hyperphosphatemia in patients with end-stage renal disease. An in vitro phosphate-binding assay is required to measure the drug's efficacy. The assay developed for this purpose involves mixing the drug (polymer) with a solution of known phosphate concentration, filtering off the polymer-phosphate complex, and quantitating the unbound phosphate concentration by ion chromatography. The binding capacity, reported as mmol of phosphate bound g of polymer(-1), is calculated from the calculated amount of bound phosphate and the weight of polymer used. The method has been validated for accuracy, precision, linearity, range, and ruggedness. PMID:10698557

Mazzeo, J R; Peters, R M; Hanus, M R; Chen, X; Norton, K A

1999-05-01

99

Determination of choline in infant formula by ion chromatography.  

PubMed

Choline was determined in infant formula by ion chromatography with suppressed conductivity detection. Samples were digested with 1M hydrochloric acid, filtered, diluted, and injected into the chromatographic system. Choline and the alkali and alkaline earth metals were separated on a high-resolution cation-exchange column and detected by suppressed conductivity. The method was linear between 2 and 200 mg/L (r2 = 0.9999), the concentration range of the diluted samples. This method accurately determined choline in powdered, concentrated, and ready-to-feed infant formulas. Recoveries of choline spikes into powdered infant formula at approximately 1, 0.8, 0.5, and 0.2 times the labeled value ranged from 85 to 114%. This method had good agreement for 8 blind duplicates. The values determined for these samples, which were used in an AOAC collaborative study of an enzymatic method, were consistent with the values determined by the enzymatic method. PMID:10513015

Laikhtman, M; Rohrer, J S

100

High performance size exclusion chromatography (IX) bulk and component analysis of silanol groups in polydimethylsiloxanes  

SciTech Connect

Methods for the bulk and molecular weight component analysis of hydroxyl groups attached to silicon in polydimethylsiloxanes of the Sylgard type have been developed. The infrared (ir) absorbance band of the silanol adduct produced by hydrogen bonding with 1,4-dioxane is used. The determination of hydroxyl content as a function of molecular weight employs an on-line size exclusion chromatography-infrared (SEC-IR) technique. Interference by vinyl or phenyl groups in the sample or by traces of water in the solvent was negligible, but water or compounds containing other types of hydroxyl groups interfered. Sensitivity of the method is about 10 ..mu..g of the silanol, as OH in the polydimethylsiloxane. Primary calibration was by proton nuclear magnetic resonance (PNMR) at a high concentration of hydroxyl groups.

Kohn, E.

1985-01-01

101

Improved potency assay for recombinant bovine somatotropin by high-performance size-exclusion chromatography.  

PubMed

A high-performance size-exclusion chromatographic method was developed for the determination of potency of recombinant bovine somatotropin (rbST) monomer and the estimation of dimer and soluble aggregates in bulk drug substances. These proteins can be completely extracted from bulk drug substances with sodium borate-ethylenediamine-tetraacetic acid disodium salt (EDTA) at pH 9.5 and separated on TSK G3000SW column with a mobile phase of pH 7.3 sodium borate-EDTA. The results demonstrated that this method was a non-denaturing assay for the determination of potency of rbST monomer and the data obtained in this study correlated well with data of the hypophysectomized rat body weight gain bioassay. The rbST monomer and dimer in the separation were verified by liquid chromatography-electrospray mass spectrometry. This method was optimized and validated. PMID:8673254

Chang, J P; Ferguson, T H; Record, P A; Dickson, D A; Kiehl, D E; Kennington, A S

1996-06-01

102

Assessment of protein entrapment in hydroxyapatite scaffolds by size exclusion chromatography.  

PubMed

Although it is well known that the textural properties of scaffolds play an important role in the process of tissue regeneration, the investigation of such effects remain difficult especially at the micro/nano level. Texture confers the material the additional ability to entrap/concentrate molecules circulating in the body fluid regardless of their binding affinity to the material. The goal of the present work is to isolate protein entrapment from protein adsorption phenomena in two macroporous hydroxyapatite scaffolds with identical chemical structure, similar macroporosity but different micro/nanoporosity using proteins of different sizes. This was achieved implementing size exclusion chromatography and using the scaffolds as chromatographic columns. The results showed that the larger the crystal size and the lower the packing density of the crystals composing the scaffold increased protein retention but decreased the protein dwelling time in the column. Differences in the amount of protein retained depended on the protein type. PMID:22627910

Espanol, Montserrat; Casals, Isidre; Lamtahri, Sarah; Valderas, Maria-Teresa; Ginebra, Maria-Pau

2012-05-25

103

Determination of selenate by single-column ion chromatography.  

PubMed

Chromatographic parameters were optimized to determine selenate (SeO4(2-)) by single-column ion chromatography with the simultaneous detection of Cl-, NO2-, NO3- and SO4(2-). Separation was conducted on a low-capacity anion-exchange column, and anions were quantified by conductimetric detection. The eluent stream consisted of 4 mM phthalic acid adjusted to pH 4.6 with sodium borate. Accurate measurement of trace amounts of SeO4(2-) was evident in the presence of high background levels of other ions including Cl-, NO-3 and up to 40 mg l-1 SO4(2-). Resolution of SeO4(2-) and SO2-4 was demonstrated up to 80 mg l-1 SO4(2-). The detection limit of SeO4(2-) was 18 micrograms l-1 with a relative standard deviation of 1.46%. PMID:3782363

Karlson, U; Frankenberger, W

1986-10-10

104

Performance evaluation of ion-exchange chromatography in capillary format.  

PubMed

The performance of a recently introduced capillary ion-exchange chromatography system was explored. Experiments were conducted in isocratic mode with a commercial capillary anion-exchange column (id = 0.4 mm, L = 15 cm) using a five-anion standard mixture. The achieved results were compared to the performance of a standard bore ion-exchange system (id = 4 mm, L = 15 cm), which was considered as a reference. The first-generation capillary columns exhibited a minimal reduced plate-height value below two witnessing a good packing quality and system performance. However, compared to the standard bore system the capillary system displayed an increased apparent C-term which could be due to a difference in packing morphology and/or possible external band-broadening contributions. For fast separations, the standard bore system outperformed the capillary system, while for complex separations both systems performed nearly equally well. In addition, the retention characteristics of the capillary system were investigated. To illustrate the suitability of the capillary system, the analysis of real-world water samples originating from two local Belgian rivers was demonstrated. PMID:23125111

Eghbali, Hamed; Bruggink, Cees; Agroskin, Yury; Pohl, Christopher A; Eeltink, Sebastiaan

2012-11-02

105

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

106

A fluorescence-detection size-exclusion chromatography-based thermostability assay to identify membrane protein expression and crystallization conditions  

PubMed Central

SUMMARY 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.

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

2012-01-01

107

Chromatography.  

ERIC Educational Resources Information Center

|This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)|

Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

108

Analysis of starch in food systems by high-performance size exclusion chromatography.  

PubMed

Starch has unique physicochemical characteristics among food carbohydrates. Starch contributes to the physicochemical attributes of food products made from roots, legumes, cereals, and fruits. It occurs naturally as distinct particles, called granules. Most starch granules are a mixture of 2 sugar polymers: a highly branched polysaccharide named amylopectin and a basically linear polysaccharide named amylose. The starch contained in food products undergoes changes during processing, which causes changes in the starch molecular weight and amylose to amylopectin ratio. The objective of this study was to develop a new, simple, 1-step, and accurate method for simultaneous determination of amylose and amylopectin ratio as well as weight-averaged molecular weights of starch in food products. Starch from bread flour, canned peas, corn flake cereal, snack crackers, canned kidney beans, pasta, potato chips, and white bread was extracted by dissolving in KOH, urea, and precipitation with ethanol. Starch samples were solubilized and analyzed on a high-performance size exclusion chromatography (HPSEC) system. To verify the identity of the peaks, fractions were collected and soluble starch and beta-glucan assays were performed additional to gas chromatography analysis. We found that all the fractions contain only glucose and soluble starch assay is correlated to the HPSEC fractionation. This new method can be used to determine amylose amylopectin ratio and weight-averaged molecular weight of starch from various food products using as low as 25 mg dry samples. PMID:23330715

Ovando-Martínez, Maribel; Whitney, Kristin; Simsek, Senay

2013-01-18

109

Determination of trans octadecenoic acids by silver-ion chromatography-gas liquid chromatography: an intercomparison of methods.  

PubMed

Several silver-ion chromatography-gas liquid chromatography (GLC) techniques for the determination of trans octadecenoic acids in partially hydrogenated vegetable fats were collaboratively evaluated. Twelve laboratories participated in the study. All collaborators used high polarity fused silica capillary columns for the separation of fatty acid methyl esters by GLC; 7 collaborators isolated trans monoenes by silver-ion liquid chromatography (Ag-LC) and the remainder used silver-ion thin-layer chromatography (Ag-TLC). Eight artificially prepared materials [soybean oil spiked with either methyl elaidate, trielaidin, or trans octadecenoates isolated from partially hydrogenated sunflower oil (PHSO)] and 2 matrix materials (PHSO and a blend of PHSO and palm oil) served as test samples. Ag-TLC and Ag-LC proved to be equivalent techniques for the prefractionation of trans monoenes. Recovery of methyl elaidate, trielaidin, or trans octadecenoates isolated from PHSO varied between 97.9-103.7% over a concentration range of 1 to 30 g trans fatty acids/100 g. Reproducibility relative standard deviation (RSDR) for the spiked samples were in the range of 3.1-8.6% for 30-1% trans monoene content. For the 2 matrix samples (mean 3.75 and 19.08% trans monoene content) RSDR was 13.2 and 3.6%. The hyphenated techniques tested proved to be highly accurate and sufficiently precise methods for the determination of trans monoenes in partially hydrogenated vegetable fats. Procedural variations of the silver-ion chromatography prefractionation step (separation mode, mobile phase, and detection systems) did not significantly influence the results of the test. Therefore, silver-ion chromatography is a robust method, which does not need rigorous standardization to achieve high precision of test results. A further benefit of the hyphenated technique is that any type of efficient polar capillary column can be used. PMID:11601469

Buchgraber, M; Ulberth, F

110

Separation and Identification op Metal Ions by Reversed Phase Then Layer Chromatography  

Microsoft Academic Search

Conditions for the simultaneous separation and identification of as many as ten different metal ions have been established using the technique of reversed-phasethin-layer chromatography. Complete resolution of the ten ions in sub-microgram amounts was achieved using a liquid ion exchanger supported on cellulose. The total time for the analysis was 3–4 hours.

Frederica V. Cornett; T. W. Gilbert

1971-01-01

111

The use of liquid chromatography for the analysis of metal ions in aqueous solutions and for the determination of water in organic matrices  

SciTech Connect

The value of a p-phenylenediammonium eluent in single-column ion chromatography is demonstrated. It is shown to be particularly useful for separating trivalent aluminum from common divalent metal ion interferences. The aluminum is detected with a conductivity detector. Postcolumn reaction in liquid chromatography is reviewed. The application of disodium 1-(2-thiazolylazo)-2-naphthol-3,6-disulfonate (TAN-3,6-S) to the detection of metal ions in single-column ion chromatography with a visible absorbance detector is explored. TAN-3,6-S is shown to complex a large number of metal ions. It is particularly useful postcolumn reagent because by the judicious selection of effluent pH, selectivity may be introduced into the detection system. Temperature is shown to affect the retention times of divalent and trivalent metal ions in ion chromatography. Factors contributing to this phenomenon are examined, and enthalpy changes for several ion-exchange reactions are calculated and compared. Two methods for the determination of water in organic matrices using liquid chromatography and a spectrophotometric detector are presented. Both employ a chromatographic separation by ion-exclusion. The first detection method makes use of solvatochromism, the shift in an organic spectrum which occurs as solvent polarity is changed. This second detection method uses a solid-phase postcolumn reactor containing a cation-exchange resin in the H{sup +} form. This reactor acts as catalyst for a reaction occurring between water and two components of the mobile phase, methanol and trans-cinnamaldehyde.

Fortier, N.E.

1988-01-01

112

How unequivocally do ion chromatography experiments determine carbon cluster geometries?  

SciTech Connect

Ion chromatography experiments on carbon clusters have provided a powerful tool for characterizing the products of the laser ablation of graphite. Using this technique, several families of carbon clusters have been observed, and their role in a plausible fullerene formation process has been hypothesized. In this work, we have examined the experimental mobility results from a theoretical perspective. Our most interesting finding is the existence of a family of three-dimensional 2 + 4 cycloaddition products whose members match the experimental mobilities of the so-called `ring III` family over a range of cluster sizes, whereas previous studies have asserted that the `ring III` clusters are planar. In agreement with previous research, we find that the `ring I` and `ring II` families consist of monocyclic and bicycle rings, respectively. However, these families should be broadly defined so as to include ring structures with carbon branches, because short carbon branches have only a negligible effect on cluster mobility. 28 refs., 6 figs., 6 tabs.

Strout, D.L.; Book, L.D.; Millam, J.M.; Xu, C.; Scuseria, G.E. [Rice Univ., Houston, TX (United States)

1994-09-01

113

Surfactant-aided size-exclusion chromatography for the purification of immunoglobulin G.  

PubMed

In the production of monoclonal antibodies, separate chains of the antibody are often present in the product mixture as well as other contaminating proteins. These fragments should be removed from the whole antibodies. This paper shows the purification of monoclonal immunoglobulin G (IgG) from its heavy chain contaminant. The heavy chain fragment is simulated experimentally using bovine serum albumin (BSA), which has approximately the same molecular weight. The purification is performed using traditional size-exclusion chromatography (SEC) and using surfactant-aided SEC (SASEC), testing two different surfactants (C(12)E(23) and Tween20) and two different gels (Sephacryl S200HR and Sephacryl S300 HR). Pulse experiments show that with SASEC both BSA and IgG are more distributed towards the solid phase than compared to using SEC. This effect is larger on IgG, the largest component than on BSA. As a consequence, azeotropes will be formed at a specific surfactant concentration. Above this concentration the selectivity is reversed and increased to values higher than obtained with conventional SEC. At 7.5% (w/w) of C(12)E(23), BSA actually elutes before IgG. These experiments further show that when using SASEC larger productivity, higher yields and lower solvent consumption can be achieved without loss of purity of IgG when compared to conventional SEC. Mathematical simulation of the separation of BSA and IgG using simulated moving bed (SMB) chromatography indicates a large increase in productivity when applying a surfactant gradient in SASEC SMB compared to conventional isocratic SEC-SMB. Furthermore, solvent consumption reductions with a factor 15 prove possible as well as concentrating the IgG by a factor 2. PMID:17543976

Horneman, D A; Ottens, M; Keurentjes, J T F; van der Wielen, L A M

2007-05-07

114

Procedure for determination of trace ions in boric acid by matrix volatilization-ion chromatography.  

PubMed

A method for determination of anions and cations in boric acid is proposed by matrix volatilization. The boric acid matrix was eliminated as trimethyl borate ester in a vapour phase matrix elimination (VPME) system using a mixture of glycerol-methanol. In this VPME system, in situ reagent purification, sample decomposition and digest evaporation were achieved in a single step. Trace anions were separated on anion-exchange column (IonPac AS17) by an isocratic elution with 15 mM sodium hydroxide and the cations on a cation-exchange column (IonPac CS12) by 20 mM hydrochloric acid as eluents. Method detection limits (3sigma) for most ions ranged from 0.3 to 8 ng/g (ppb). Recovery experiments combined with comparison of data obtained by other methods were employed to verify the accuracy of the proposed method. Application of the method to determine trace levels of anions like acetate, oxalate, sulfate, phosphate and cations such as lithium, sodium, potassium, magnesium and calcium in two highly pure grades of boric acid using ion chromatography is demonstrated. PMID:12885085

Dash, K; Karunasagar, D; Thangavel, S; Chaurasia, S C

2003-06-20

115

Differentiation and quantification of linear alkyl benzenesulfonate isomers by liquid chromatography-ion-trap mass spectrometry  

Microsoft Academic Search

Discrimination and quantitation of the 20 positional isomers of C10–C13 linear alkyl benzenesulfonates (LASs), based on the use of reversed-phase liquid chromatography-electrospray ionisation in negative ion mode ion-trap mass spectrometry, was undertaken. Discrimination was achieved by LAS MS-MS analysis into the ion trap, by monitoring specific fragment ions resulting from the benzylic cleavage of the carbon alkyl chain on both

Loreto Lunar; Soledad Rubio; Dolores Pérez-Bendito

2004-01-01

116

Studying arsenite-humic acid complexation using size exclusion chromatography-inductively coupled plasma mass spectrometry.  

PubMed

Arsenic (As) can form complexes with dissolved organic matter (DOM), which affects the fate of arsenic in waste sites and natural environments. It remains a challenge to analyze DOM-bound As, in particular by using a direct chromatographic separation method. Size exclusion chromatography (SEC) hyphenated with UV spectrophotometer and inductively coupled plasma mass spectrometry (ICP-MS) was developed to characterize the complexation of arsenite (As(III)) with DOM. This SEC-UV-ICP-MS method is able to differentiate As(III)-DOM complexes from free As species and has the advantage of direct determination of both free and DOM-bound As(III) through mild separation. The suitability of this method for studying As(III)-DOM complexation was demonstrated by its application, in combination with the Scatchard plot and nonlinear regression of ligand binding model, for characterizing As(III) complexation with humic acid (HA) in the absence or presence of natural sand. The results suggest that, consistent with polyelectrolytic nature of HA, the As(III)-HA complexation should be accounted for by multiple classes of binding sites. By loosely classifying the binding sites into strong (S1) and weak (S2) sites, the apparent stability constants (K(s)) of the resulting As-DOM complexes were calculated as logK(s1)=6.5-7.1 while logK(s2)=4.7-5.0. PMID:22664255

Liu, Guangliang; Cai, Yong

2012-05-17

117

Size-exclusion chromatography of poly(ethylene 2,6-naphthalate).  

PubMed

A solvent mixture of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and dichloroacetic acid (DCAA) is used to dissolve difficultly soluble poly(ethylene 2,6-naphthalate) (PEN). Solutions can be diluted and analyzed in a common size-exclusion chromatography (SEC) eluent, HFIP. The HFIP/DCAA mixture is better at dissolving PEN than either solvent individually and it is easier and safer to work with than phenolic and strongly acidic eluents. Dissolution temperatures between 50 and 60 °C are sufficiently low to minimize hydrolytic degradation of the polyester. PEN does not dissolve in the solvent mixture if the water concentration is greater than 0.76 wt%, and preferably the water content should be less than 0.13 wt% to eliminate minor prepeak artifacts. The procedure is suitable for PEN that is less than 48% crystalline, including prepolymers, oriented films and some solid-state polymerized materials. Highly crystalline polymers can be melt-quenched into a more amorphous state to render them soluble. The dilute solution conformational properties of PEN are compared to PET in HFIP, and molar mass-intrinsic viscosity scaling constants and unperturbed dimensions are calculated from SEC data. PMID:22897859

Mourey, T H; Slater, L A; Galipo, R C; Janes, D L; Moody, R E

2012-07-28

118

Separation of SHRP asphalts by preparative size exclusion chromatography. [Strategic Highway Research Program  

SciTech Connect

Eight SHRP core asphalts have been separated by means of preparative size exclusion chromatography (SEC) on Bio-Beads S-X1 gel using toluene as a solvent. Recoveries are almost quantitative and reproducibilities are good. Molecular weight (MW) data obtained for the SEC fractions are in accord with expectations. The initial eluates are much higher in MW than subsequent eluates, and MW's of fractions decrease in MW with increasing fraction number. Initial eluates in these SEC separations do not fluoresce when irradiated with 350 nm light. This is probably due to quenching as a result of incorporation of normally fluorescing aromatic molecules in micellar associations. Subsequent SEC fractions are fluorescent to 350 nm light. Each of the eight asphalts separated by preparative SEC exhibited unique chromatograms. The chromatograms were compared with viscosity data for asphalts in which the highest MW fractions were removed by preparative SEC. The viscosity reductions observed in these residual fractions were greatest in those asphalts whose preparative SEC chromatograms exhibited the most pronounced bimodal distributions.

Branthaver, J.F.; Duvall, J.J.; Petersen, J.C. (Western Research Inst., Laramie, WY (United States))

1990-07-01

119

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.

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

120

Continuous spin fractionation and characterization by size-exclusion chromatography for styrene-butadiene block copolymers.  

PubMed

Linear and star-shaped styrene-butadiene block copolymers synthesized by anionic polymerization of butadiene and styrene were fractionated by applying a newly developed large-scale fractionation technique, named continuous spin fractionation (CSF). Their molecular weight and polydispersity index (d=M(w)/M(n)) were measured with size-exclusion chromatography and static light scattering. For the linear triblock copolymer a fractionation via temperature variation turned out to be better suited than the usual isothermal procedure. The star-shaped polymer with the d value of 1.33 was fractionated in two CSF steps to get the targeted sample, which has a considerably more uniform structure and a narrower molecular weight distribution (d=1.11). The corresponding starting linear diblock copolymer was fractionated in one step reducing d from 1.68 to 1.17. With one set of simple laboratory equipment, 1kg polymer can be fractionated per day. Utilizing CSF, for the first time, we fractionated successfully the block copolymers. PMID:16466731

Xiong, Xiaopeng; Eckelt, John; Wolf, Bernhard A; Zhang, Zhengjun; Zhang, Lina

2006-02-08

121

Mass Spectrometric Analysis of Intact Human Monoclonal Antibody Aggregates Fractionated by Size-Exclusion Chromatography  

PubMed Central

ABSTRACT Purpose The aim of this study was to develop a method to characterize intact soluble monoclonal IgG1 antibody (IgG) oligomers by mass spectrometry. Methods IgG aggregates (dimers, trimers, tetramers and high-molecular-weight oligomers) were created by subjecting an IgG formulation to several pH jumps. Protein oligomer fractions were isolated by high performance size exclusion chromatography (HP-SEC), dialyzed against ammonium acetate pH 6.0 (a mass spectrometry-compatible volatile buffer), and analyzed by native electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS). Results Monomeric and aggregated IgG fractions in the stressed IgG formulation were successfully isolated by HP-SEC. ESI-TOF MS analysis enabled us to determine the molecular weight of the monomeric IgG as well as the aggregates, including dimers, trimers and tetramers. HP-SEC separation and sample preparation proved to be necessary for good quality signal in ESI-TOF MS. Both the HP-SEC protocol and the ESI-TOF mass spectrometric technique were shown to leave the IgG oligomers largely intact. Conclusions ESI-TOF MS is a useful tool complementary to HP-SEC to identify and characterize small oligomeric protein aggregates.

Kukrer, Basak; Filipe, Vasco; van Duijn, Esther; Kasper, Piotr T.; Vreeken, Rob J.; Heck, Albert J. R.

2010-01-01

122

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

Microsoft Academic Search

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

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

2008-01-01

123

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

Microsoft Academic Search

Electrophoresis in 10% polyacrylamide gel in the presence of denaturants and size-exclusion chromatography in Sephadex G-75\\u000a in 7 M urea were used for the comparative analysis of humic substances isolated from a typical chernozem, soddy-podzolic soil,\\u000a and chestnut soil and from the easily decomposable organic matter (plant detritus) contained in these soils. After the electrophoresis,\\u000a the gel with naturally colored

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

2008-01-01

124

Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography–multiangle laser light scattering  

Microsoft Academic Search

The feasibility of size exclusion chromotography (SEC)–multiangle laser-light scattering as a technique to investigate aggregation and degradation of glycosylated and nonglycosylated proteins, and antibodies under various conditions such as addition of detergent, changes in pH, and variation of protein concentration and heat stress temperature was examined. Separation of proteins and their aggregates was performed using SEC–high-performance liquid chromatography. Detection of

Hongping Ye

2006-01-01

125

Study of the stability of cellulose–holocellulose solutions in N, N-dimethylacetamide–lithium chloride by size exclusion chromatography  

Microsoft Academic Search

Solutions in N,N-dimethylacetamide (DMAC)–LiCl were prepared from two different pulps (sulphite pulp from softwood and cotton linters) in different ageing states. Degradation of the stirred solutions at 35–40°C was observed by determining the molecular masses by size exclusion chromatography (SEC). We showed that under these conditions cellulose and holocelluloses are degraded in DMAC–LiCl and that the rate of degradation is

Heike Jerosch; Bertrand Lavédrine; Jean-Claude Cherton

2001-01-01

126

The Role of Size Exclusion Chromatography-Flame Atomic Absorption Spectrometry in the Treatment Chemistry of Potable Water  

Microsoft Academic Search

The percentage composition of Al13, [AlO4Al12(OH)24(H2O)12]7+, in water treatment coagulants is an important criterion in the development and use of polymeric coagulants. Polymeric coagulants are generally used in cold climates or with highly turbid waters. Size exclusion chromatography–flame atomic absorption spectrometry (SEC-FAAS) can separate Al13 and monomeric Al within 6 min. The percentage composition of Al13 and monomeric Al is

Marina C. Koether

2002-01-01

127

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

128

Refolding and purification of recombinant human interferon-? expressed as inclusion bodies in Escherichia coli using size exclusion chromatography  

Microsoft Academic Search

A size exclusion chromatography (SEC) process, in the presence of denaturant in the refolding buffer was developed to refold\\u000a recombinant human interferon-? (rhIFN-?) at a high concentration. The rhIFN-? was overexpressed inE. coli, resulting in the formation of inactive inclusion bodies (IBs). The IBs were first solubilized in 8 M urea as the denaturant,\\u000a and then the refolding process performed

Yi-Xin Guan; Hai-Xue Pan; Yong-Gui Gao; Shan-Jing Yao; Man-Gi Cho

2005-01-01

129

Investigation of molecular masses and aggregation of ?- d-glucan from Poria cocos sclerotium by size-exclusion chromatography  

Microsoft Academic Search

?-d-Glucan PC3 (weight-average molecular mass=9.15·104, polydispersity=1.6), a linear glucan from Poria cocos sclerotium, was fractionated by a preparative size-exclusion chromatography (SEC) column packed with regenerated cellulose gels using dimethyl sulfoxide (DMSO) as mobile phase. The molecular masses and aggregation of the fractions were investigated by using analytical SEC, viscometry and membrane osmometry under different conditions. The results of SEC analysis

Lina Zhang; Qiong Ding; Diya Meng; Liwei Ren; Guang Yang; Yonggang Liu

1999-01-01

130

Ethanol-sodium chloride-phosphate mobile phase for size-exclusion chromatography of poly(ethylene glycol) modified proteins  

Microsoft Academic Search

The use of an aqueous sodium chloride-phosphate mobile phase for size-exclusion chromatography of poly(ethylene glycol) modified (PEGylated) proteins resulted in premature degradation of silica-based gel filtration columns. This column degradation was manifested as peak tailing and loss of resolution. An aqueous ethanol-sodium chloride-phosphate mobile phase was identified which extended column lifetimes without loss of resolution or change in peak shape.

Joseph J. Ratto; Sheila R. O'Conner; Adrian R. Distler; Gay-May Wu; David Hummel; Michael J. Treuheit; Alan C. Herman; Janice M. Davis

1997-01-01

131

Determination of metal ions by ion chromatography with precolumn electrochemical preconcentration.  

PubMed

The determination of heavy metals in concentrations less than 10(-6) mol/L by ion chromatography with conductivity detection requires a preconcentration step. Therefore, a special electrochemical equipment and method was developed for the on-line preconcentration of the divalent metals Ni, Co, Zn and Cd and their subsequent ion chromatographic determination. The loop of the injection valve of an ion chromatograph was replaced by an electrochemical flow-through-cell with a gold working electrode, a platinum auxiliary electrode and a silver/silver sulphate reference electrode. The preconcentration step consists of the deposition of the reduced metals on the electrode surface during a continuous pumping of the sample solution through the cell. After switching of the mobile phase through the cell, the analytes are injected after their reoxidation directly into the mobile phase. A new preconcentration step is simultaneously possible during the actual chromatographic run. An effective separation of the analytes from the matrix is also possible with the proposed system. A maximum of metal ion accumulation was obtained after 120 min in the galvanostatic mode on a gold tube electrode. The detection limits for Co(II), Ni(II), Zn(II) and Cd(II) were improved by a factor of 7.7, 10.4, 11.2, 14.0, respectively, and were in the 0.1 micromol/L concentration range with a RSD of 2-6%. The accumulation of metal ions was disturbed in the presence of Cr(III). PMID:15067479

Hissner, F; Mattusch, J; Werner, G

1996-03-01

132

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 ...

133

Automated separation of Sr from natural water samples or carbonate rocks by high performance ion chromatography  

Microsoft Academic Search

An automated separation of strontium prior to isotopic analysis from liquid samples (river water, seawater or solutions resulting from natural carbonate dissolution) was developed using High Performance Ion Chromatography (HPIC) technique. The experimental set up consists of an automatic sampler, an ion chromatograph and a fraction collector.To evaluate the performance of the set up, we compare the separation of strontium

Laure Meynadier; Caroline Gorge; Jean-Louis Birck; Claude J. Allègre

2006-01-01

134

Separation of Some Post-Transition Metal Ions by Thin-Layer Chromatography in Molten Salts  

Microsoft Academic Search

A method is described for the use of molten salts as an eluent for thin-layer chromatography of inorganic ions. The separation of some post-transition metal ions can be successfully accomplished through the use of alkali metal nitrate eutectic melts. The mechanism of separation appears to be one of cation exchange with the silica gel used as the adsorbent. By appropriate

Steven Abbe; Leonard F. Druding

1969-01-01

135

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...

136

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

137

Performance of ion chromatography in the determination of anions and cations in various natural waters with elevated mineralization  

Microsoft Academic Search

The performance of ion chromatography in the determination of anions and cations in natural mineral waters of different composition and different total mineralization was evaluated. Up to 12 ions of the 20 usually included in extended chemical analysis of natural waters were successfully determined by ion chromatography alone. At least 98.60% and up to 99.96% of total cation composition of

N. Gros; B. Gorenc

1997-01-01

138

[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

139

Comprehensive two-dimensional liquid chromatography: ion chromatography × reversed-phase liquid chromatography for separation of low-molar-mass organic acids.  

PubMed

In the work presented here a novel approach to comprehensive two-dimensional liquid chromatography is evaluated. Ion chromatography is chosen for the first-dimension separation and reversed-phase liquid chromatography is chosen for the second-dimension separation mode. The coupling of these modes is made possible by neutralising the first-dimension effluent, containing KOH, prior to transfer to the second-dimension reversed-phase column. A test mixture of 24 low-molar-mass organic acids is used for optimisation of the system. Three food and beverage samples were analysed in order to evaluate the developed methodology, the resulting two-dimensional separation is near-orthogonal, the set-up is simple and all instrumental components are available commercially. The method proved to be robust and suitable for the analysis of wine, orange juice and yogurt. PMID:20598313

Brudin, Stella S; Shellie, Robert A; Haddad, Paul R; Schoenmakers, Peter J

2010-06-08

140

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

141

Size-exclusion chromatography in the measurements of concentration and molecular weight of some EOR polymers  

SciTech Connect

Procedures that involve the use of size exclusion chromatography (SEC) for the measurement of concentration and weight-averaged molecular weight, M-bar/sub w/, of some EOR polymers were developed and found to give improved detectability, accuracy, and/or efficiency. The separation of polymer from low-molecular-weight impurities by size allows unambiguous detection of polymer properties such as concentration and M-bar/sub w/. A combination of an SEC column of a pore size small enough to exclude the polymer totally and a mobile phase of ionic strength of 1.5 was found suitable for the separation of polyacrylamide, partially hydrolyzed polyacrylamide, cationic polyacrylamide derivative, and xanthan polysaccharide from impurities. Concentration detection of the separated polymer sample with a variable-wavelength ultraviolet (UV) detector was found to give superior detectability over detection by refractive index difference. A wavelength of 214 nm (2,140 A) was used for the detection of these polymers on the basis of the spectra of samples purified by dialysis. With the active polymer assay determined by reprecipitation into a nonsolvent, the detection limit by UV was determined to be <0.1 ..mu..g/cm/sup 3/ for polyacrylamide and a cationic polyacrylamide derivative, <0.2 ..mu..g/cm/sup 3/ for partially hydrolyzed polyacrylamide, and <0.7 ..mu..g/cm/sup 3/ for a xanthan polysaccharide. The linear calibration range was up to 500 ..mu..g/cm/sup 3/. The precision of the concentration measurement was better than 4% for polyacrylamide and its derivative and 5% for polysaccharide at a 95% confidence level.

Hunt, J.A.; Young, T.S.; Green, D.W.; Willhite, G.P.

1988-08-01

142

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...

143

REVERSED-PHASE ION-PAIR THIN LAYER CHROMATOGRAPHY OF SOME ALKALOIDS  

Microsoft Academic Search

The retention behaviour of some alkaloids, as test samples, on reversed-phase pre-coated thin layer chromatography in the presence of different ion-pair reagents was investigated. Trifluoroacetic acid (TFA), pentafluoropropionic acid (PFPA), and heptaflluorobutyric acid (HFBA) were used as counter ions. The dependence of RF values on the eluent composition, the chain length of the ion-pair reagent and the ratio of two

Abdalla Shalaby; Hawa Khalil

1999-01-01

144

Sodium and potassium benzoate and benzoic acid as eluents for ion chromatography  

SciTech Connect

Benzoic acid is introduced as an eluent and is compared with benzoate salt eluents. Detector response to sample ions in single-column ion chromatogrphy is compared with dual-column (suppressed) ion chromatography. Benzoic acid has a higher background conductance; however, samples separated with benzoate salt eluents. Comparable sample peak areas are found with suppressor column treated benzoate eluents and benzoic acid eluents. Equations are described which predict detector response for a variety of conditions.

Gjerde, D.T.; Fritz, J.S.

1981-12-01

145

Refolding of detergent-denatured lysozyme using ?-cyclodextrin-assisted ion exchange chromatography.  

PubMed

Chromatography-based protein refolding is widely used. Detergent is increasingly used for protein solubilization from inclusion bodies. Therefore, it is necessary to develop a refolding method for detergent-denatured/solubilized proteins based on liquid chromatography. In the present work, sarkosyl-denatured/dithiothreitol-reduced lysozyme was used as a model, and a refolding method based on ion exchange chromatography, assisted by ?-cyclodextrin, was developed for refolding detergent-denatured proteins. Many factors affecting the refolding, such as concentration of urea, concentration of ?-cyclodextrin, pH and flow rate of mobile phases, were investigated to optimize the refolding conditions for sarkosyl-denatured lysozymes. The results showed that the sarkosyl-denatured lysozyme could be successfully refolded using ?-cyclodextrin-assisted ion exchange chromatography. PMID:22887001

Zhang, Li; Zhang, Qinming; Wang, Chaozhan

2012-08-13

146

Determination of molecular formulas and structural regularities of low molecular weight fulvic acids by size-exclusion chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry.  

PubMed

Size-exclusion chromatography was coupled to a quadrupole time-of-flight mass spectrometer using electrospray ionization in the negative ion mode to analyze Suwannee River fulvic acid. About 220 exact masses of low molecular weight fulvic acids (FAs) were measured in the range from m/z 190 to 350, and molecular formulas could be deduced for all these molecular masses. All molecular formulas can be described by the superimposition of three homologous series in the FA mixture: (a) a series of hydrogen homologs constituted of five to six members for a given number of carbons and oxygens; (b) a series of alkyl chain homologs with stepwise addition of one methylene group; and (c) isobaric compounds that differ by the formal replacement of an oxygen atom by a methane group. Product ion spectra of the FA species reflect the repeated parallel losses of carbon dioxide and water. The minimum number of carboxylate groups and the maximum number of hydroxy moieties could be determined from the product ion spectra. Furthermore, it was obvious that the structural differences between homologs in the three series are located in the carbon backbone of the FA rather than in its extremities that are expelled as neutral fragments. These structural regularities reduce the complexity of FA mixtures to a certain set of yet unknown basic structures. PMID:15329870

These, Anja; Winkler, Marcus; Thomas, Christoph; Reemtsma, Thorsten

2004-01-01

147

High-Performance Chelation Chromatography of Metal Ions on Sorbents with Grafted Iminodiacetic Acid  

Microsoft Academic Search

The chromatographic behavior of some alkaline-earth, transition, heavy, and rare-earth metals on a number of complexing sorbents containing surface iminodiacetic acid (IDA) functional groups is studied. The conditions under which metal retention is determined by complexation on the sorbent surface were established, and the main principles of a new variant of the liquid chromatography, i.e., high-performance chelation ion chromatography (HPCIC),

P. N. Nesterenko; O. A. Shpigun

2002-01-01

148

QUANTIFICATION OF Caz+DEPENDENT PROTEASE ACTIVITIES BY HYDROPHOBIC AND ION-EXCHANGE CHROMATOGRAPHY  

Microsoft Academic Search

Hydrophobic and ionexchange chromatography were compared for yield of Ca2+- dependent proteases and their inhibitor in studies designed to quantify Ca2+-dependent proteases activity for comparative purposes. Ion-exchange (DEAE-Sephacel) proved superior to hydrophobic chromatography (Phenyl-Sepharose). Under the proper conditions, DEAE-Sephacel effectively separated low-calcium-requiring form of Ca2+-dependent protease (CDP-I) and CDP inhibitor. Characterization of the assay system for components of the Ca*+-dependent

Mohammad Koohmaraie

149

Quantitative amino acid analysis of feedstuff hydrolysates by reverse phase liquid chromatography and conventional ion-exchange chromatography.  

PubMed

Corn, soybean meal, and isolated soybean protein samples were acid-hydrolyzed and analyzed for amino acid content by reverse phase liquid chromatography (LC) and by conventional ion-exchange chromatography (IEC) using an amino acid analyzer. The former method employed pre-column derivatization with orthophthalaldehyde (OPTA)/ethanethiol and fluorescence detection. In the LC procedure, glycine and threonine were not resolved, and proline and cyst(e)ine were not detected. In general, amino acid values obtained by LC and IEC compared closely within and across feedstuffs, and both agreed well with published amino acid composition data. The notable exceptions were aspartic acid, glutamic acid, and alanine. Results of this study suggest that reverse phase LC with pre-column OPTA derivatization can be applied to accurately measure primary amino acids in individual feedstuffs. PMID:6501145

Elkin, R G

150

Characterization of polymer-based monolithic capillary columns by inverse size-exclusion chromatography and mercury-intrusion porosimetry.  

PubMed

Organic-polymer monolithic capillary columns were prepared in fused-silica capillaries by a radical copolymerization reaction of butyl methacrylate and ethylene dimethacrylate monomers in the presence of 1,4-butanediol and 1-propanol as porogen solvents and azobisisobutyronitrile as the initiator. The porous properties could be influenced by changing the ratio of porogen solvents, while keeping the monomer content constant, or by changing the ratio of monomers to porogen in the polymerization mixture. The resulting chromatographic properties, such as porosity, permeability were determined under high-pressure liquid chromatography (HPLC) conditions. The mesopore size distributions of the monolithic materials determined with inverse size-exclusion chromatography (ISEC) were compared with those measured by mercury-intrusion porosimetry. Both techniques are complementary. While mercury-porosimetry measures the entire range of pore sizes and provides more physical information on the monoliths, ISEC is very suitable for determining the size of mesopores in the swollen monoliths. PMID:18206896

Urban, Jirí; Eeltink, Sebastiaan; Jandera, Pavel; Schoenmakers, Peter J

2008-01-08

151

Size exclusion chromatography (XIII): Identification and quantitation of silicon hydride containing oligomeric components of Sylgard prepolymers. [Polydimethylsiloxane  

SciTech Connect

Methods for the identification and quantitation of oligomeric, silicon hydride (SiH), containing components of Sylgard prepolymers (polydimethylsiloxane: PDMS) have been developed. They employ a combination of size exclusion chromatography (SEC), with infrared (ir) and differential refractometer (DR) detection and gas chromatography/mass spectrometry (GC/MS) verification. The identified oligomers were present at about 20% of total prepolymer and contained from one to six SiH linkages per molecule. Such lower molecular weight oligomers may contribute to the vapor pressure of resins prepared from the prepolymers since they may contain a significant number of molecules which have only one or two SiH groups and are not capable of forming large polymeric structures. 5 refs., 8 figs., 2 tabs.

Kohn, E.; Chisum, M.E.; Moore, K.L.

1987-12-01

152

Analysis of triglyceride isomers by silver-ion high-performance liquid chromatography  

Microsoft Academic Search

Silver ion chromatography (Ag-HPLC), utilizing columns packed with silver ions bonded to a silica or similar substrate, has proven to be a powerful technique for the analytical separation of cis and trans geometric and positional fatty acid methyl ester (FAME) and triacylglycerol (TAG) isomers. In this manuscript, we utilize an HPLC column chiller\\/heater to study the effects of Ag-HPLC column

R Adlof; G List

2004-01-01

153

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

154

Integrated separation scheme for coal-derived liquids using ion-exchange and adsorption chromatography  

Microsoft Academic Search

A separation scheme for coal-derived liquids has been developed that separates by functionality into discrete compound classes using ion-exchange resins; neutrals are further subdivided into fractions differing in polarity, structure, and molecular weight by adsorption chromatography. Sufficient material can be separated to allow further characterization at both gross structural and molecular levels. It gives excellent overall reproducibility (+\\/- 4%) and

Michael G. Strachan; R. B. Johns

1986-01-01

155

Analysis of polar organic micropollutants in water with ion chromatography–electrospray mass spectrometry  

Microsoft Academic Search

The coupling of ion chromatography (IC) with electrospray mass spectrometry (ES-MS) opens new ways for the determination of polar organic micropollutants in water samples. The technique of conductivity suppression has been found to reduce the background signal in the range of about two-orders of magnitude leading to a significant increase in sensitivity. In addition, the formation of salt adducts has

Karl-Heinz Bauer; Thomas P Knepper; Anke Maes; Viktor Schatz; Martin Voihsel

1999-01-01

156

Analysis of alkyl sulfonates and carboxylates using high performance ion chromatography  

Microsoft Academic Search

Summary  A simple and general method for the determination of both C1?C10 alkyl sulfonates and alkyl carboxylates using the same basic methodology, based on High Performance ion Chromatography, using\\u000a relatively simple eluent systems allowing fast analysis with both high sensitivity and accuracy is presented.

H. A. J. M. Bevers; R. Hulst

2000-01-01

157

Retention properties of triacylglycerols on silver ion high-performance liquid chromatography  

Microsoft Academic Search

The retention properties of series of synthetic disaturated-monounsaturated (1 to 6 double bonds) triacylglycerols and the common seed oil triacylglycerols on a silver ion high-performance liquid chromatography column have been studied in quantitative terms. Retention factors were found to increase stepwise, with a saturated dimonoenoic species being held ten times and trilinolenin ten thousand times more strongly than a disaturated

Boryana Nikolova-Damyanova; William W. Christie; Bengt G. Herslöf

1995-01-01

158

Microcolumn ion chromatography of inorganic monovalent cations with indirect photometric detection and a silica gel column  

Microsoft Academic Search

A microcolumn ion chromatography system for the separation of inorganic monovalent cations was developed using effused silica column (50mm length × 0.35 mm i.d.) packed with porous silica gel. The separation was carried out by using benzyltrimethylammonium chloride in aqueous acetonitrile as the mobile phase. Six inorganic monovalent cations such as lithium, sodium, ammonium, potassium, ribidium and cesium were separated

Edison Munaf; Rahmiana Zein; Toyohide Takeuchi; Tomoo Miwa

1996-01-01

159

Trace enrichment and ion chromatographie determination of metal oxoanions in environmental water samples  

Microsoft Academic Search

For the analysis of trace metal oxoanions using non-suppressed ion chromatography (IC), the presence of nitrite, nitrate and bromide in high quantities can seriously interfere with direct spectrophotometric detection. Similarly, direct analysis of water of high salt content like hard water will also encounter the problem of column disturbance. Sample pretreatment using a chelating resin for matrix cleanup and trace

Y. S. Fung; K. L. Dao

1995-01-01

160

Automated quantitative analysis of wood carbohydrates by borate complex ion exchange chromatography  

Microsoft Academic Search

A simple automated analytical method for separation and quantitative determination of sugars from acidic and enzymatic hydrolysates of wood polysaccharides via borate complex ion exchange chromatography is described. Samples are analysed without any interferring manipulation like derivatization, deionization or deproteinization, and even sulphuric acid hydrolysates can be directly applied to the column. As little as 0.5 µg of an individual

M. Sinner; M. H. Simatupang; H. H. Dietrichs

1975-01-01

161

Determination of nitrate, phosphate and organically bound phosphorus in coral skeletons by ion chromatography  

Microsoft Academic Search

Nitrate, phosphate and sulphate incorporated in the aragonitic skeletons of corals (Porites) were analyzed by ion chromatography (IC). All anion analyses were performed using a Dionex 4500i IC system with Dionex columns, conductivity detector and computer interface. The anions were separated on an AS4A separator column behind an AG4 guard column, and the background conductivity of the eluent was suppressed

William Shotyk; Ina Immenhauser-Potthast; Hubert A. Vogel

1995-01-01

162

RAPID DISTILLATION COUPLED WITH ION CHROMATOGRAPHY FOR THE DETERMINATION OF SIX ALKYLAMINES IN COSMETICS  

Microsoft Academic Search

A rapid distillation method coupled with ion chromatography was developed for simultaneous determination of methylamine, ethylamine, dimethylamine, trimethylamine, propylamine, and butylamine in cosmetics. The distillation system was designed professionally to achieve rapid distillation in less than 3 min and eliminate the interferences of alkali metals, alkaline earth and organic compounds effectively. Samples were distilled using vapour stream under alkaline conditions and

Zhixiong Zhong; Gongke Li; Binghui Zhu; Zhibin Luo

2012-01-01

163

Rapid quantitative method for total brominated vegetable oil in soft drinks using ion chromatography  

Microsoft Academic Search

A simple, quantitative and rapid method for total brominated vegetable oil (BVO) using ion chromatography (IC) with suppressed conductivity detection was developed and successfully applied to soft drinks with results expressed as inorganic bromide anion. The procedure involves extraction of BVO with diethyl ether and treatment with zinc dust in a solution of acetic acid, giving recoveries ranging between 92.5

Ashraf A. Yousef; Alaa B. Abbas; Bassam Sh. Badawi; Wafaa Y. Al-Jowhar; Esam A. Zain; Seham A. El-Mufti

2012-01-01

164

Using ultrapure water in ion chromatography to run analyses at the ng\\/L level  

Microsoft Academic Search

Thanks to enhanced capabilities, ion chromatography (IC) occupies an increasing position in many types of applications. Achieving ideal performances for an extended life-time can only be reached, however, if the IC system is operated in optimum experimental conditions. Among the various parameters that need to be controlled, water is particularly important, because it is used throughout the analysis, from sample

Ichiro Kano; Elodie Castillo; Daniel Darbouret; Stéphane Mabic

2004-01-01

165

APPLICATION OF SILVER ION CHROMATOGRAPHY TO THE SEPARATION OF CONJUGATED LINOLEIC ACID ISOMERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Conjugated linoleic acid (CLA; 9c,11t-18:2), present in dairy products and beef, has been reported in animals to have anticarcinogenic, growth-promoting, antiatherogenic, anti-diabetic, and lean body mass-enhancing properties. Silver ion chromatography has, over the decades, become an important met...

166

Application of Ion Chromatography to the Investigation of Real-World Samples  

ERIC Educational Resources Information Center

|The use of ion chromatography (IC) as a means to teach important analytical concepts while giving the students a valuable opportunity to identify and investigate a real-world system of interest to them is described. A single IC apparatus can be tailored for different classes of analyses by the selection of different column-eluent combinations.|

Whelan, Rebecca J.; Hannon, Theresa E.; Zare, Richard N.

2004-01-01

167

Comprehensive peptidome analysis of mouse livers by size exclusion chromatography prefractionation and nanoLC-MS/MS identification.  

PubMed

Peptidome analysis has received increasing attention in recent years. Cancer diagnosis by serum peptidome has also been reported by peptides' profiling for discovery of peptide biomarkers. Tissue, which may have a higher biomarker concentration than blood, has not been investigated extensively by means of peptidome analysis. Here, a method for the peptidome analysis of mouse liver was developed by the combination of size exclusion chromatography (SEC) prefractionation with nano-liquid chromatography-tamdem mass spectrometry (nanoLC-MS/MS) analysis. The extracted peptides from mouse liver were separated according to their molecular weight using a size exclusion column. MALDI-TOF MS was used to characterize the molecular weight distribution of the peptides in fractions eluted from the SEC column. The low molecular weight (LMW) (MW < 3000 Da) peptides in the collected fractions were directly analyzed by LC-MS/MS which resulted in the identification of 1181 unique peptides (from 371 proteins). The high molecular weight (HMW) (MW > 3000 Da) peptides in the early two fractions from the SEC column were first digested with trypsin, and the resulted digests were then analyzed by LC-MS/MS, which led to the identification of 123 and 127 progenitor proteins of the HMW peptides in fractions 1 and 2, respectively. Analysis of the peptides' cleavage sites showed that the peptides are cleaved in regulation, which may reflect the protease activity and distribution in body, and also represent the biological state of the tissue and provide a fresh source for biomarker discovery. PMID:17269736

Hu, Lianghai; Li, Xin; Jiang, Xinning; Zhou, Houjiang; Jiang, Xiaogang; Kong, Liang; Ye, Mingliang; Zou, Hanfa

2007-02-01

168

Developing liquid chromatography ion mobility mass spectometry techniques.  

PubMed

When a packet of ions in a buffer gas is exposed to a weak electric field, the ions will separate according to differences in their mobilities through the gas. This separation forms the basis of the analytical method known as ion mobility spectroscopy and is highly efficient, in that it can be carried out in a very short time frame (micro- to milliseconds). Recently, efforts have been made to couple the approach with liquid-phase separations and mass spectrometry in order to create a high-throughput and high-coverage approach for analyzing complex mixtures. This article reviews recent work to develop this approach for proteomics analyses. The instrumentation is described briefly. Several multidimensional data sets obtained upon analyzing complex mixtures are shown in order to illustrate the approach as well as provide a view of the limitations and required future work. PMID:16097888

Valentine, Stephen J; Liu, Xiaoyun; Plasencia, Manolo D; Hilderbrand, Amy E; Kurulugama, Ruwan T; Koeniger, Stormy L; Clemmer, David E

2005-08-01

169

On-line coupling of size exclusion chromatography with mixed-mode liquid chromatography for comprehensive profiling of biopharmaceutical drug product.  

PubMed

A methodology based on on-line coupling of size exclusion chromatography (SEC) with mixed-mode liquid chromatography (LC) has been developed. The method allows for simultaneous measurement of a wide range of components in biopharmaceutical drug products. These components include the active pharmaceutical ingredient (protein) and various kinds of excipients such as cations, anions, nonionic hydrophobic surfactant and hydrophilic sugars. Dual short SEC columns are used to separate small molecule excipients from large protein molecules. The separated protein is quantified using a UV detector at 280 nm. The isolated excipients are switched, online, to the Trinity P1 mixed-mode column for separation, and detected by an evaporative light scattering detector (ELSD). Using a stationary phase with 1.7 ?m particles in SEC allows for the use of volatile buffers for both SEC and mix-mode separation. This facilitates the detection of different excipients by ELSD and provides potential for online characterization of the protein with mass spectrometry (MS). The method has been applied to quantitate protein and excipients in different biopharmaceutical drug products including monoclonal antibodies (mAb), antibody drug conjugates (ADC) and vaccines. PMID:22999205

He, Yan; Friese, Olga V; Schlittler, Michele R; Wang, Qian; Yang, Xun; Bass, Laura A; Jones, Michael T

2012-09-10

170

THE DETERMINATION OF MAGNESIUM IN ZIRCONIUM USING ION EXCHANGE CHROMATOGRAPHY  

Microsoft Academic Search

The method is based upon the ability of zirconium to form an easily ; soluble oxalate complex compound which is not adsorbed by a cation exchanger ; (catfonite). The magnesium in the solution is, however, adsorbed by the ; cationite and can then be eluted with hydrochloric acid. An ion exchange resin ; with SOâH as the active group was

S. V. Yelinson; M. S. Limonik

1958-01-01

171

ION CHROMATOGRAPHY OF PHYTATE IN ROOTS AND TUBERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ion chromatographic method for the quantification of phytate (InsP6) in foods was adapted for the analysis of roots and tubers. To maximize sensitivity, UV detection following post-column derivatization was compared with evaporative light scattering detection (ELSD). Detection limits for phyta...

172

Separation and Determination of Heavy Metals Associated with Low Molecular Weight Chelators in Xylem Saps of Indian Mustard ( Brassica juncea ) by Size Exclusion Chromatography and Atomic Absorption Spectrometry  

Microsoft Academic Search

To elucidate the role of low molecular weight chelators in long-distance root-to-shoot transport of heavy metals in Indian\\u000a mustard, an “off-line” size exclusion high-performance liquid chromatography–graphite furnace atomic absorption spectrometry\\u000a was developed to investigate heavy metals associated with low molecular weight chelators in xylem saps of Indian mustard (Brassica juncea). The size exclusion chromatogram presented only the peaks with molecular

Zhenggui G. Wei; Jonathan Woonchung C. Wong; Haiyan Y. Zhao; Huijuan J. Zhang; Huixin X. Li; Feng Hu

2007-01-01

173

An Empirical Formula from Ion Exchange Chromatography and Colorimetry  

Microsoft Academic Search

Experimental determination of the empirical formula for sodium salicylate, Nax(C7H5O3)y, using colorimetry and cation exchange. A Beer's Law plot is prepared for salicylate using 0.0050 M salicylic acid solution. Colorimetric analysis is performed on the salicylate ion in the form of an aqueous ferric complex, which is intensely violet-red, using a simple, inexpensive colorimeter constructed from readily available electronic parts

Steven D. Johnson

1996-01-01

174

Quantifying accumulation or exclusion of H+, HO?, and Hofmeister salt ions near interfaces  

PubMed Central

Recently, surface spectroscopies and simulations have begun to characterize the non-uniform distributions of salt ions near macroscopic and molecular surfaces. The thermodynamic consequences of these non-uniform distributions determine the often-large ion-specific effects of Hofmeister salts on a very wide range of processes in water. For uncharged surfaces, where these nonuniform ion distributions are confined to the first few layers of water at the surface, a two-state approximation to the distributions of water and ions, called the salt ion partitioning model (SPM) has both molecular and thermodynamic signiicance. Here, we summarize SPM results quantifying the local accumulation of H+, exclusion of HO?, and range of partitioning behavior of Hofmeister anions and cations near macroscopic and molecular interfaces. These results provide a database to interpret or predict Hofmeister salt effects on aqueous processes in terms of structural information regarding amount and composition of the surface exposed or buried in these processes.

Pegram, L. M.; Record, M. T.

175

Size-Exclusion Chromatography Using Mixed-Bed Columns with Dimethylformamide at Near-Ambient Conditions: Comparison of ?styragel Ht Linear and Pl Gel Mixed-Bed Columns  

Microsoft Academic Search

Mixed-bed size-exclusion chromatography (SEC) columns packed with 10 ?m particles are evaluated at near-ambient conditions using dimethylformamide (DMF) containing 0.01 M LiBr as the eluent. Two popular columns (HT Linear from Millipore Waters Chromatography Division and PL Gel from Polymer Laboratories) are evaluated in terms of operating pressure, resolution, fits to calibration data, and the accuracy of molecular weight distributions

T. H. Mourey; T. G. Bryan

1991-01-01

176

Determination of a new antifungal agent, voriconazole, by multidimensional high-performance liquid chromatography with direct plasma injection onto a size-exclusion column  

Microsoft Academic Search

A fully automated method has been developed for the analysis of a new antifungal agent, voriconazole, in human plasma. Multidimensional chromatography was used with size-exclusion chromatography as the first step to separate plasma protein from the drug and internal standard which were then trapped on a precolumn of pellicular ODS. A reversed-phase column, Spherisorb ODS2, then separated drug and internal

David A. Stopher; Richard Gage

1997-01-01

177

Determination of amines used in the oil and gas industry (upstream section) by ion chromatography.  

PubMed

During production and purification of crude oil and natural gas several different amines are used as chemicals or operating materials, e.g. film forming long chain amines as corrosion inhibitors, steam volatile amines for pH correction and corrosion protection, alkanolamines as absorbents in sour gas treatment plants, etc. For analytical checks, e.g. determination of corrosion inhibitor concentration in produced media, classical chemical methods are used predominantly, because most of them can be performed in small field laboratories. Some amines, especially the small molecular aliphatic and heterocyclic amines can also be determined by ion chromatography. In our laboratory two types of separation columns (IonPac CS10 and CS12A) were available for ion chromatographic separation. The analysis of the amines in low-salt-containing water, soft water or steam condensate can be performed without problems. The presence of alkali and/or alkaline earth ions in the sample can lead to coelution with these ions, to poor peak resolution or enhanced analysis times, depending on the chromatographic conditions. This work shows some examples of ion chromatography applications for the determination of low-molecular-mass ethanolamines, morpholine and piperazine and discusses the possible interferences and troubles caused by alkali and alkaline earth ions in the matrix. PMID:10457490

Kadnar, R

1999-07-30

178

Determination of bromide ion residues in broccoli after fumigation with methyl bromide by nonsuppressed ion-chromatography.  

PubMed

A nonsuppressed ion chromatography method using conductivity detection was performed to determine the concentration of bromide ions in broccoli following fumigation with methyl bromide (MB). After fumigation by MB with concentration up to 40 g/m3, bromide residue (BR) was considerably increased from the trace amount on unfumigated broccoli to about 12 ppm on fumigated broccoli. For probing the location of BR, broccoli was divided into stems and florets. The BRs were measured separately, and the results indicated that BRs only appear in the florets of broccoli. PMID:16526462

Huang, Hung-Chang; Lai, Shu-Fen; Liu, Yung-Chuan; Chen, Hon-Yi; Tu, Wu-Chun

179

An Empirical Formula from Ion Exchange Chromatography and Colorimetry  

NASA Astrophysics Data System (ADS)

Experimental determination of the empirical formula for sodium salicylate, Nax(C7H5O3)y, using colorimetry and cation exchange. A Beer's Law plot is prepared for salicylate using 0.0050 M salicylic acid solution. Colorimetric analysis is performed on the salicylate ion in the form of an aqueous ferric complex, which is intensely violet-red, using a simple, inexpensive colorimeter constructed from readily available electronic parts and PVC pipe. Determination of sodium content is conducted using cation exchange, using simple re-usable exchange columns, followed by titration with OH-. The procedure is involved, yet has been conducted by high school chemistry students as a lab final.

Johnson, Steven D.

1996-12-01

180

Indirect determination of cyanide by single-column ion chromatography  

SciTech Connect

The procedure was developed by modification of a pneumoamperometric method which uses the reaction of cyanide with iodine, since the final concentration of iodide is proportional to the initial concentration of cyanide. The sample is diluted so that the cyanide concentration is in the range of .5 - 10 ppm, acetate buffer is added to adjust the pH to a value between 4.5 and 6. Excess iodine is added in 95% ethanol, sample is diluted to constant volume and allowed to stand for ca 5 min. Small aliquots of sample are injected slowly into the ion chromatograph through a precolumn containing XAD-4 resin. The excess iodine is adsorbed on this precolumn. The ion chromatograph adsorbs the iodide reaction product on XAD-1 resin. The iodide is removed by elution with sodium phthalate. Retention time is ca 5 min. Contamination of the system may be prevented by the removal of the precolumn for iodine desorption using nitric acid in acetone and water. 2 figures, 3 tables.

DuVal, D.L.; Fritz, J.S.; Gjerde, D.T.

1982-04-01

181

Size Exclusion Chromatography of Meiamine-, Urea, and Phenolformaldehyde Resins Using N, N-Dimethylformamide as Eluent  

Microsoft Academic Search

Resins, hardly soluble in THF or chloroform, in the oligomer region were analyzed using DMF as solvent and a polystyrene column for oligomers. This column, 25 cm × 8 mm i.d., is the exclusive use of DMF and has the number of theoretical plates of 6000 per 25 cm. Polynuclear methylol melamines were resolved into individual polynuclear species and peaks

Takeshi Matsuzaki; Yoshinori Inoue; Tetsuo Ookubo; Sadao Mori

1980-01-01

182

Application of Size Exclusion Chromatography in the Development and Characterization of Nanoparticulate Drug Delivery Systems  

Microsoft Academic Search

The successful production of effective nanoparticulate drug delivery systems depends on maintaining the characteristics of the starting materials and the final formulation. Since compendial standards for traditional drug delivery systems do not always apply to nanosystems, analytical procedures for nanosized delivery systems must be established. This will ensure the quality of such products as they reach the marketplace. Size exclusion

Daniel P. Otto; Hermanus C. M. Vosloo; Melgardt M. de Villiers

2007-01-01

183

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

184

Fractionation of cis- and trans-oleic, linoleic, and conjugated linoleic fatty acid methyl esters by silver ion high-performance liquid chromatography 1 Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 1  

Microsoft Academic Search

Silver ion high-performance liquid chromatography (Ag-HPLC) using two commercially available columns connected in series and a solvent of 0.5% acetonitrile in hexane (1.0 ml\\/min), was used to fractionate a mixture of conjugated 18:2 isomers (as methyl esters) and resulted in an elution order (10 ?g sample size) of: 9-trans,11-trans-18:2; 9-cis,11-trans-18:2. A more complex mixture of cis and trans 9-18:1, 9,11-18:2

R Adlof; T Lamm

1998-01-01

185

Evolution of natural organic matter by size exclusion chromatography during photocatalytic degradation by solvothermal-synthesized titanium dioxide.  

PubMed

This study shows the effect of different titanium dioxides in transforming the structural properties of natural organic matter (NOM) during photocatalytic degradation with a solar UV light simulator. Titanium dioxide (TiO(2)) synthesized by the sol-gel method coupled with the solvothermal technique and Degussa P-25 TiO(2) were used. The evolution of NOM degradation was followed by size exclusion chromatography with dissolved organic carbon, ultraviolet and fluorescence detection (SEC-DOC, SEC-UV(254) and SEC-Fl(254/450)). For both catalysts, there was a preferential degradation of the larger molecules of NOM into medium and smaller molecular size fractions. However, the synthesized TiO(2) was found to be more efficient than Degussa P-25 TiO(2) for DOC removal, especially UV(254) absorption and Fl(254/450) removal. PMID:22370203

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

2012-02-14

186

Characterization of dissolved organic matter using high-performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) with a multiple wavelength absorbance detector.  

PubMed

High-performance liquid chromatography-size exclusion chromatography (HPLC-SEC) coupled with a multiple wavelength absorbance detector (200-445 nm) was used in this study to investigate the apparent molecular weight (AMW) distributions of dissolved organic matter (DOM). Standard DOM, namely humic acid, fulvic acid and hydrophilic acid, from the Suwannee River were tested to ascertain the performance and sensitivity of the method. In addition to four compounds groups: humic substances (Peak 1, AMW 16 kD), fulvic acids (Peak 2, AMW 11 kD), low AMW acids (Peak 3, AMW 5 kD), and low AMW neutral and amphiphilic molecules, proteins and their amino acid building blocks (Peak 4, AMW 3 kD), an new group that appears to include low AMW, 6-10 kD, humic substances was found based on investigating the spectra at various elution times. The spectroscopic parameter S(>365) (slope at wavelengths >365 nm) was determined to be a good predictor of the AMW of the DOM. The detector wavelength played an important role in evaluating the AMW distribution. For some fractions, such as the humic and low AMW non-aromatic substances, the error in measurement was ± 30% as determined by two-dimensional chromatograms detected at an artificially selected wavelength. HPLC-SEC with multiple wavelength absorbance detection was found to be a useful technique for DOM characterization. It characterized the AMW distributions of DOM more accurately and provided additional, potentially important information concerning the properties of DOM with varying AMWs. PMID:22369846

Yan, Mingquan; Korshin, Gregory; Wang, Dongsheng; Cai, Zhenxiao

2012-02-25

187

Absolute molecular weight determination of hypromellose acetate succinate by size exclusion chromatography: Use of a multi angle laser light scattering detector and a mixed solvent  

Microsoft Academic Search

Molecular weight distribution is an important quality attribute for hypromellose acetate succinate (HPMCAS), a pharmaceutical excipient used in spray-dried dispersions. Our previous study showed that neither relative nor universal calibration method of size exclusion chromatography (SEC) works for HPMCAS polymers. We here report our effort to develop a SEC method using a mass sensitive multi angle laser light scattering detector

Raymond Chen; Nicholas Ilasi; Sonja S. Sekulic

2011-01-01

188

Amylopectin aggregation as a function of starch phosphate content studied by size exclusion chromatography and on-line refractive index and light scattering  

Microsoft Academic Search

Starches with a natural 65-fold span in covalently bound phosphate content were prepared from five different crops including sorghum, cassava, three potato varieties and an exotic ginger plant, Curcuma zedoaria, with extreme starch phosphate content. These starches were subjected to size exclusion chromatography with refractive index detection (SEC\\/RI). A simple and rapid method for starch solubilisation was used. The conditions

Andreas Blennow; Anne Mette Bay-Smidt; Rogert Bauer

2001-01-01

189

Chemical characterization of the ambient organic aerosol soluble in water: 2. Isolation of acid, neutral, and basic fractions by modified size-exclusion chromatography  

Microsoft Academic Search

A method employing size-exclusion chromatography (SEC) with Total Organic Carbon detection is developed to isolate and quantify the water-soluble organic carbon (WSOC) component of ambient aerosol particles by acid, neutral, and basic functional groups. The method provides unique quantitative insights into the characteristics and possible sources of a large fraction of the organic aerosol. The SEC is combined with a

Amy P. Sullivan; Rodney J. Weber

2006-01-01

190

Analysis of a Styrene-Butadiene Graft Copolymer by Size Exclusion Chromatography II. Determination of the Branching Exponent with the Help of a Polymerization Model  

Microsoft Academic Search

A styrene — butadiene graft copolymer is analyzed by size exclusion chromatography (SEC) with on-line viscometry with the aim of estimating the ? exponent that relates the two branching parameters through g = g?. Three copolymer samples synthesized in a solution polymerization of styrene in the presence of polybutadiene were analyzed. Theoretical predictions on the branching characteristics were obtained with

J. R. Vega; D. A. Estenoz; H. M. Oliva; G. R. Meirra

2001-01-01

191

[Determination of the distribution of relative molecular mass of organic matter by high pressure size exclusion chromatography with UV and TOC detectors].  

PubMed

An on-line high pressure size exclusion chromatography (HPSEC) with UV and TOC detectors was adapted to examine the distribution of relative molecular mass of natural organic matter (NOM). Through synchronous determination of UV254 and TOC responses in a wide range of relative molecular mass, it was possible to accurately characterize the structure of NOM, especially for some non-aromatic and non-conjugated double bond organics which have low response to UV. It was found that, TOC detector was capable of detecting all kinds of organic matters, including sucrose, sodium alginate and other hydrophilic organic compounds. The sample volume had a positively linear correlation with the TOC response, indicating that the larger volume would produce stronger responses. The effect of ion strength was relatively low, shown by the small decrease of peak area (1.2% ) from none to 0.2 mol x L(-1) NaCl. The pH value of tested samples should be adjusted to neutral or acidic because when the samples were alkaline, the results might be inaccurate. Compared to the sample solvents adopted as ultrapure water, the samples prepared by mobile phase solvents had less interference to salt boundary peak. The on-line HPSEC-UV-TOC can be used accurately to characterize the distribution of relative molecular mass and its four fractions in River Xiang. PMID:23243872

Zhang, Han; Dong, Bing-Zhi

2012-09-01

192

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

193

High performance ion chromatography measurement of sulfate in 20 mM phosphate extracts of soil  

Microsoft Academic Search

High Performance Ion Chromatography (HPIC) methods for measuring sulfate in 20 mM phosphate extracts of soil need to cope with low sulfate (down to 0.1 ppm S) in up to 5000 times the molar concentration of phosphate and potassium or calcium, a diversity of solutes including organic compounds, and colloidal particles.Anions were detected by electrical conductivity rather than indirect photometry,

J. H. Watkinson; M. J. Kear

1994-01-01

194

Determination of rare-earth elements in coal using microwave digestion and gradient ion chromatography  

Microsoft Academic Search

The combined application of microwave digestion, high-performance ion chromatography (HPIC) and on-line sample solution concentration provides a technique for the routine determination of rare-earth elements (REE) in coals. Acid dissolution of whole powdered coal samples using microwave pressure digestion removes the necessity of dry ashing to eliminate organic carbon, providing considerable time savings and significantly reducing the risk of sample

Ronald T. Watkins; Moira K. Ridley; M. A. Bruno Pougnet; James P. Willis

1995-01-01

195

High-performance ion chromatography assessment of inorganic and organic nitrogen fractions in potatoes  

Microsoft Academic Search

.  A new high-performance ion chromatography assay for organic and inorganic nitrogen analysis has been proposed and examined.\\u000a In the devised protocol, inorganic sample constituents were measured after ultrasonically assisted water extraction. The amine\\u000a and amide nitrogen content was assessed after modified Kjeldahl digestion and determined as NH4\\u000a +, and the total nitrogen content was quantified as NO3\\u000a ? after microwave-facilitated

Bartlomiej Prusisz; Lucyna Ja?kiewicz; Pawel Pohl

2006-01-01

196

Rapid Analysis of Preservatives in Beverages by Ion Chromatography with Series Piezoelectric Quartz Crystal as Detector  

Microsoft Academic Search

A rapid ion chromatography method employing a series piezoelectric quartz crystal (SPQC) detector was used to analyze sorbic and benzoic acids in wine, syrups, cola, and Wahaha drink. The analytical procedure was performed using a Shimpack IC-A1 anion-exchange column and 3.0 mM sodium carbonate with sodium hydroxide to adjust the pH to 9.5 as the mobile phase. The high resolution

You-Tao Xie; Po Chen; Wan-Zhi Wei

1999-01-01

197

Dynamic ion exchange chromatography for determination of number of fissions in thorium-uranium dioxide fuels  

Microsoft Academic Search

High-performance liquid chromatography and the use of ¹³⁸La as a fission monitor have been examined for the determination of the number of fissions and burnup in (Th, U)Oâ fuels. The fission product ¹³⁹La in a solution of irradiated fuel was separated on a reversed phase dynamically modified with 1-octanesulfonate, and the eluted metal ions were monitored by an ''on-line'' postcolumn

C. H. Knight; R. M. Cassidy; B. M. Recoskie; L. W. Green

1984-01-01

198

Screening of Drugs and Toxic Compounds with Liquid Chromatography-Linear Ion Trap Tandem Mass Spectrometry  

Microsoft Academic Search

Background: In clinical and forensic toxicology, general unknown screening is used to detect and identify exog- enous compounds. In this study, we aimed to develop a comprehensive general unknown screening method based on liquid chromatography coupled with a hybrid triple-quadrupole linear ion trap mass spectrometer. Methods: After solid-phase extraction, separation was performed using gradient reversed-phase chromatogra- phy. The mass spectrometer

Francois-Ludovic Sauvage; Franck Saint-marcoux; Benedicte Duretz; Didier Deporte; Gerard Lachatre; Pierre Marquet

199

Improved separation of conjugated fatty acid methyl esters by silver ion-high-performance liquid chromatography  

Microsoft Academic Search

Operating from one to six silver ion-high-performance liquid chromatography (Ag+-HPLC) columns in series progressively improved the resolution of the methyl esters of conjugated linoleic acid (CLA) isomeric\\u000a mixtures from natural and commercial products. In natural products, the 8 trans, 10 cis-octadecadienoic (18?2) acid was resolved from the more abundant 7 trans, 9 cis-18?2, and the 10 trans, 12 cis-18?2 was

Najibullah Sehat; Rainer Rickert; Magdi M. Mossoba; John K. G. Kramer; Martin P. Yurawecz; John A. G. Roach; Richard O. Adlof; Kim M. Morehouse; Jan Fritsche; Klaus D. Eulitz; Hans Steinhart; Yuoh Ku

1999-01-01

200

Determination of beryllium in a stream sediment by high-performance chelation ion chromatography  

Microsoft Academic Search

High-performance chelation ion chromatography (HPCIC), involving a chelating silica substrate bonded with aminomethylphosphonic acid, has been developed as a novel technique for the quantitative determination of beryllium in complex matrices. An isocratic separation method, using an eluent containing 1 M KNO3, 0.5 M HNO3 and 0.08 M ascorbic acid, allowed the Be2+ to elute away from the sample matrix peak

M. J Shaw; S. J Hill; P Jones; P. N Nesterenko

2000-01-01

201

Determination of residual anabolic steroid in meat by gas chromatography–ion trap–mass spectrometer  

Microsoft Academic Search

The use of natural and synthetic anabolic steroids in animal fattening has been prohibited in Taiwan and many countries because of their potential toxic effect on public health. This paper describes a newly developed gas chromatography–ion trap–mass spectrometry (GC–IT–MS) method for the quantitative determination of various residual anabolic steroids in meat. Anabolic steroid was derivatized with N-methyl-N-trimethylsilytrifluoroacetamide prior to GC–IT–MS

Ming-Ren Fuh; Shu-Yen Huang; Tzeun-Yean Lin

2004-01-01

202

Purification of proteins containing zinc finger domains using immobilized metal ion affinity chromatography  

Microsoft Academic Search

Heterologous proteins are frequently purified by immobilized metal ion affinity chromatography (IMAC) based on their modification with a hexa-histidine affinity tag (His-tag). The terminal His-tag can, however, alter functional properties of the tagged protein. Numerous strategies for the tag removal have been developed including chemical treatment and insertion of protease target sequences in the protein sequence. Instead of using these

Irena Vorá?ková; Šárka Suchanová; Pavel Ulbrich; William E. Diehl; TomᚠRuml

2011-01-01

203

Determination of dichloroacetic acid and trichloroacetic acid by liquid-liquid extraction and ion chromatography  

Microsoft Academic Search

An extraction technique using MTBE (methyl tert. butyl ether) and reagent water in combination with ion chromatography and\\u000a conductivity determination was developed to quantify dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) concentrations\\u000a in raw water after chlorination. The detection limit of the method was 0.45 and 1.50 ?g\\/L for DCAA and TCAA, respectively.\\u000a Mean values of recovery ranged from 90

Ya-Wen Ko; T. J. Gremm; G. Abbt-Braun; F. H. Frimmel; Pen-Chi Chiang

2000-01-01

204

Determination of Urinary Glucose by a Flow Injection Analysis Amperometric Biosensor and Ion-Exchange Chromatography  

Microsoft Academic Search

A practical biosensor system has been developed for the determination of urinary glucose using a flow-injection analysis (FIA)\\u000a amperometric detector and ion-exchange chromatography. Glucose oxidase was immobilized onto porous aminopropyl glass beads\\u000a via glutaraldehyde activation to form an immobilized enzyme column. On the basis of its negative charge at pH 5.5, endogenous\\u000a urate in urine samples was effectively retained by

K. B. Male; J. H. T. Luong

1992-01-01

205

Determination of sulfur anions by ion chromatography–postcolumn derivation and UV detection  

Microsoft Academic Search

A novel method for determination of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed. All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5mmol\\/L sodium carbonate and 0.8mmol\\/L sodium bicarbonate at a flow-rate of 1.0mL\\/min. The postcolumn derivation solution

Mei Lan Chen; Ming Li Ye; Xue Ling Zeng; Yun Chang Fan; Zhu Yan

2009-01-01

206

Fractionation of Aspergillus niger cellulases by combined ion exchange affinity chromatography  

SciTech Connect

Eight chemically modified cellulose supports were tested for their ability to adsorb components of the Aspergillus niger cellulase system. At least two of the most effective adsorbents, aminoethyl cellulose and carboxymethyl cellulose, were shown to be useful for the fractionation of cellulases. These supports apparently owe their resolving capacity to both ion exchange and biospecific binding effects; however, the relative importance of each effect is unknown. These observations form the basis for a new cellulase fractionation technique, combined ion exchange-affinity chromatography. 22 references.

Boyer, R.F.; Allen, T.L.; Dykema, P.A.

1987-02-05

207

Determination of metal ions using ion chromatography and indirect amperometric detection  

SciTech Connect

A method for determination of metal ions subsequent to ion chromatographic separation has been devised. The method is based on indirect amperometric detection whereby a decrease in an oxidation current, proportional to the concentration of metal ion, is monitored. In this particular work, an easily oxidized ligand is added postcolumn. Upon complexation with the metal ions, the ligand is rendered electroinactive at the preselected potential. The fact that the ligand is oxidized at low anodic potentials results in a selective detection system.

Hojabri, H.; Lavin, A.G.; Wallace, G.G.; Riviello, J.M.

1987-01-01

208

The Determination of Hyaluronan Molecular Weight Distribution by Means of High-Performance Size Exclusion Chromatography  

Microsoft Academic Search

The high-performance liquid chromatographic (HPLC) method relevant to the size exclusion chromatographic mode (SEC) used for the distribution analysis of high-molecular-weight hyaluronans is described. The HPLC fillings used, to which was applied a phosphate buffer (50 mM, pH 7.8) effluent, consisted of a cross-linked hydroxyethylmethacrylate derivative gel (HEMA-BIO), which is commercially available, and a highly porous aminopropyl-silica sorbent (SG-10-6000-NH2), which

E. Orviský; L. Šoltés; P. Chabr?ek; I. Novák; V. Kéry; M. Stan?íková; I. Vinš

1992-01-01

209

Size exclusion chromatography of cellulose in LiCl\\/ N, N-dimethylacetamide  

Microsoft Academic Search

Size exclusion of cellulose in LiCl\\/N,N-dimethylacetamide has been used for the past 15 years, yet much of the current research is still devoted to fundamental studies, as many issues regarding column calibration, separation mechanisms and solution behavior have not been resolved yet. The paper reviews practical aspects of sample preparation and it is demonstrated that sample heating and several techniques

Matija Strli?; Jana Kolar

2003-01-01

210

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.

2013-05-15

211

Selective extraction of benzoic acid from landfill leachate by solid-phase extraction and ion-exchange chromatography  

Microsoft Academic Search

In this work a simple method was described for selective extraction of benzoic acid from landfill leachate samples. The samples were submitted to solid-phase extraction (SPE) with XAD-4 resin as the stationary phase and ion-exchange chromatography (IEC) using the ion-exchange resin Amberlyst A-27. The instrumental analysis was performed by gas chromatography with mass spectrometric detection (GC–MSD). Benzoic acid was isolated,

Irajá do Nascimento Filho; Patricia Schossler; Lisiane Santos Freitas; Maria Inês S Melecchi; Maria Goreti Rodrigues Vale; Elina Bastos Caramão

2004-01-01

212

High-performance size-exclusion chromatography of humic substances on the hydroxyethyl methacrylate column  

Microsoft Academic Search

HEMA, the copolymer of 2-hydroxyethyl methacrylate and ethylene dimethacrylate, has proven to be a suitable stationary phase for the size-exclusion chromatographic (SEC) characterization of humic substances in a wide pH range. The SEC measurements were performed typically with alkaline borate-based mobile phase: 0.025mol\\/l Na2B4O7, 0.025mol\\/l NaCl, 0.001mol\\/l Na4P2O7, pH 9.1. After calibrating with globular protein standards, apparent molecular weights of

Pavel Janoš; Ivana Zat?epálková

2007-01-01

213

Investigation of the ion-exchange behaviour of titania: Application as a packing material for ion chromatography  

Microsoft Academic Search

Summary  Titania synthesized in this laboratory has previously been tested under reversed-phase conditions to assess its ion-exchange\\u000a behaviour. Although in reversed-phase chromatography with acetic acid-sodium acetate buffer as mobile phase titania behaved\\u000a as an anion-exchanger only, retention data suggested either that it behaved as a cation exchanger at higher mobile phase pH\\u000a or that the retention of cationic solutes was inhibited

K. Tani; Y. Suzuki

1997-01-01

214

Determination of thiocyanate (biomarkers of ETS) and other inorganic ions in human nasal discharge samples using ion chromatography.  

PubMed

Environmental tobacco smoke (ETS) is a mixture of air and tobacco smoke containing more than 4000 chemical substances. In view of the health risks of many of these substances, studies are needed to determine biomarkers of exposure to ETS constituents in people who actively or passively are exposed to the toxic compounds. The methodologies for determining most biomarkers from saliva, urine and blood samples are known, but methods for analyzing these compounds in nasal discharges are not available. The objective of this work was to develop an analytical procedure for the determination of thiocyanate and other biomarker compounds in samples of nasal discharge using ion chromatography. PMID:23850246

Narkowicz, Sylwia; Polkowska, ?aneta; Mar?, Mariusz; Simeonov, Vasil; Namie?nik, Jacek

2013-07-12

215

Anion content of snow by suppressed and non-suppressed ion chromatography  

SciTech Connect

Both suppressed and non-suppressed ion chromatographic methods were employed in the analysis of snow sampled from the Rocky Mountains for Cl/sup -/, NO/sub 3//sup -/, and SO/sub 4//sup 2 -/. By suppressed ion chromatography the concentration of these anions was found to be less than 1 mg/liter. These concentrations are lower than what can be determined using commercially available non-suppressed systems. To overcome this problem, the samples may be preconcentrated or a larger sample used. Due to complications arising on using a larger sample, in the absence of preconcentration, each sample must be analyzed twice by the non-suppressed ion chromatographic procedure. By comparison, the suppressed procedure is a factor of 10 more sensitive than this non-suppressed procedure. Even so, the results obtained by each of these procedures are not significantly different one from the other. 14 references, 2 figures, 1 table.

Jenke, D.R.; Mitchell, P.K.; Pagenkopf, G.K.

1983-11-01

216

Ion exchange liquid chromatography method for the direct determination of small ribonucleic acids.  

PubMed

Bioanalysis of siRNAs is challenging due to their size (5-14kDa) and negative charge across the backbone, which complicates both sample preparation and chromatography. We present here a one step sample preparation combined with non-denaturing anion exchange chromatography with UV detection for the quantitation of siRNA and its chain shortened metabolites. The sample preparation uses a novel lysis buffer with proteinase K to effectively isolate siRNA from cells and formulated media with greater than 95% recovery. The ion exchange chromatography allows for a lower limit of quantitation of 6ngmL(-1) in cells and media equivalent to 6ng/200,000cells. This method is applied to study the uptake of siRNA in prostate cancer cells and the disappearance in the media and siRNA metabolism. siRNA metabolites are identified by matching the retention time of standards to metabolite peaks. Identification is further confirmed by mass spectrometry. To our knowledge this is the first ion exchange method reported for the quantitation of siRNA from a biological matrix. It is also the first non-denaturing chromatographic method reported for siRNA quantitation. PMID:24091375

McGinnis, A Cary; Cummings, Brian S; Bartlett, Michael G

2013-08-31

217

Megadalton complexes in the chloroplast stroma of Arabidopsis thaliana characterized by size exclusion chromatography, mass spectrometry, and hierarchical clustering.  

PubMed

To characterize MDa-sized macromolecular chloroplast stroma protein assemblies and to extend coverage of the chloroplast stroma proteome, we fractionated soluble chloroplast stroma in the non-denatured state by size exclusion chromatography with a size separation range up to approximately 5 MDa. To maximize protein complex stability and resolution of megadalton complexes, ionic strength and composition were optimized. Subsequent high accuracy tandem mass spectrometry analysis (LTQ-Orbitrap) identified 1081 proteins across the complete native mass range. Protein complexes and assembly states above 0.8 MDa were resolved using hierarchical clustering, and protein heat maps were generated from normalized protein spectral counts for each of the size exclusion chromatography fractions; this complemented previous analysis of stromal complexes up to 0.8 MDa (Peltier, J. B., Cai, Y., Sun, Q., Zabrouskov, V., Giacomelli, L., Rudella, A., Ytterberg, A. J., Rutschow, H., and van Wijk, K. J. (2006) The oligomeric stromal proteome of Arabidopsis thaliana chloroplasts. Mol. Cell. Proteomics 5, 114-133). This combined experimental and bioinformatics analyses resolved chloroplast ribosomes in different assembly and functional states (e.g. 30, 50, and 70 S), which enabled the identification of plastid homologues of prokaryotic ribosome assembly factors as well as proteins involved in co-translational modifications, targeting, and folding. The roles of these ribosome-associating proteins will be discussed. Known RNA splice factors (e.g. CAF1/WTF1/RNC1) as well as uncharacterized proteins with RNA-binding domains (pentatricopeptide repeat, RNA recognition motif, and chloroplast ribosome maturation), RNases, and DEAD box helicases were found in various sized complexes. Chloroplast DNA (>3 MDa) was found in association with the complete heteromeric plastid-encoded DNA polymerase complex, and a dozen other DNA-binding proteins, e.g. DNA gyrase, topoisomerase, and various DNA repair enzymes. The heteromeric >or=5-MDa pyruvate dehydrogenase complex and the 0.8-1-MDa acetyl-CoA carboxylase complex associated with uncharacterized biotin carboxyl carrier domain proteins constitute the entry point to fatty acid metabolism in leaves; we suggest that their large size relates to the need for metabolic channeling. Protein annotations and identification data are available through the Plant Proteomics Database, and mass spectrometry data are available through Proteomics Identifications database. PMID:20423899

Olinares, Paul Dominic B; Ponnala, Lalit; van Wijk, Klaas J

2010-04-26

218

Megadalton Complexes in the Chloroplast Stroma of Arabidopsis thaliana Characterized by Size Exclusion Chromatography, Mass Spectrometry, and Hierarchical Clustering*  

PubMed Central

To characterize MDa-sized macromolecular chloroplast stroma protein assemblies and to extend coverage of the chloroplast stroma proteome, we fractionated soluble chloroplast stroma in the non-denatured state by size exclusion chromatography with a size separation range up to ?5 MDa. To maximize protein complex stability and resolution of megadalton complexes, ionic strength and composition were optimized. Subsequent high accuracy tandem mass spectrometry analysis (LTQ-Orbitrap) identified 1081 proteins across the complete native mass range. Protein complexes and assembly states above 0.8 MDa were resolved using hierarchical clustering, and protein heat maps were generated from normalized protein spectral counts for each of the size exclusion chromatography fractions; this complemented previous analysis of stromal complexes up to 0.8 MDa (Peltier, J. B., Cai, Y., Sun, Q., Zabrouskov, V., Giacomelli, L., Rudella, A., Ytterberg, A. J., Rutschow, H., and van Wijk, K. J. (2006) The oligomeric stromal proteome of Arabidopsis thaliana chloroplasts. Mol. Cell. Proteomics 5, 114–133). This combined experimental and bioinformatics analyses resolved chloroplast ribosomes in different assembly and functional states (e.g. 30, 50, and 70 S), which enabled the identification of plastid homologues of prokaryotic ribosome assembly factors as well as proteins involved in co-translational modifications, targeting, and folding. The roles of these ribosome-associating proteins will be discussed. Known RNA splice factors (e.g. CAF1/WTF1/RNC1) as well as uncharacterized proteins with RNA-binding domains (pentatricopeptide repeat, RNA recognition motif, and chloroplast ribosome maturation), RNases, and DEAD box helicases were found in various sized complexes. Chloroplast DNA (>3 MDa) was found in association with the complete heteromeric plastid-encoded DNA polymerase complex, and a dozen other DNA-binding proteins, e.g. DNA gyrase, topoisomerase, and various DNA repair enzymes. The heteromeric ?5-MDa pyruvate dehydrogenase complex and the 0.8–1-MDa acetyl-CoA carboxylase complex associated with uncharacterized biotin carboxyl carrier domain proteins constitute the entry point to fatty acid metabolism in leaves; we suggest that their large size relates to the need for metabolic channeling. Protein annotations and identification data are available through the Plant Proteomics Database, and mass spectrometry data are available through Proteomics Identifications database.

Olinares, Paul Dominic B.; Ponnala, Lalit; van Wijk, Klaas J.

2010-01-01

219

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

220

Influence of soil type and extraction conditions on perchlorate analysis by ion chromatography.  

PubMed

Perchlorate is a stable anion that has been introduced into the environment through activities related to its production and use as a solid rocket propellant. Perchlorate is thought to transport through soils without being adsorbed; thus, for determination of perchlorate in soil, samples are typically extracted with water prior to analysis. The completeness of extraction depends on perchlorate existing as a free ion within the soil matrix. In this study, perchlorate extraction efficiency was evaluated with five soil types under two different oxygen states. For each soil, 30% (w/w) slurries were prepared and equilibrated under either oxic or anoxic conditions prior to spiking with a stock solution of sodium perchlorate, and the slurries were then maintained for 1-week or 1-month. At the end of the exposure, slurries were centrifuged and separated into aqueous and soil phases. After phase separation, the soil was washed first with deionized water and then with 50mM NaOH, producing second and third aqueous phases, respectively. Perchlorate concentrations in the three aqueous phases were determined using ion chromatography. The results obtained from this study suggest that matrix interference and signal suppression due to high conductivity have greater effects upon observed perchlorate concentrations by ion chromatography than does perchlorate interaction with soil. Thus, a single water extraction is sufficient for quantitative determination of perchlorate in soil. PMID:17092539

MacMillan, Denise K; Dalton, Shana R; Bednar, Anthony J; Waisner, Scott A; Arora, Prem N

2006-11-07

221

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

222

Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography-multiangle laser light scattering.  

PubMed

The feasibility of size exclusion chromotography (SEC)-multiangle laser-light scattering as a technique to investigate aggregation and degradation of glycosylated and nonglycosylated proteins, and antibodies under various conditions such as addition of detergent, changes in pH, and variation of protein concentration and heat stress temperature was examined. Separation of proteins and their aggregates was performed using SEC-high-performance liquid chromatography. Detection of analytes was carried out with on-line UV, refractive index, and multiangle laser light-scattering detectors. Quantification and molecular weight determination were performed using commercial software. Aggregation and degradation were examined under various conditions and quantitative results are presented for bovine serum albumin, choriogonadotropin, glyceraldehyde-3-phosphate dehydrogenase, Herceptin, and ReoPro. This method can simultaneously determine both the quantities and the molecular weights of macromolecules from a single injection. The determination of molecular weight is absolute which avoids misleading results caused by molecular shape or interactions with the column matrix. This technique is valuable not only for assessing the extent of aggregation but also for effectively monitoring molecule degradation as evidenced by molecular weight reduction and change in monomer amount. PMID:16839514

Ye, Hongping

2006-06-09

223

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

224

Reactivity of anticancer metallodrugs with serum proteins: new insights from size exclusion chromatography-ICP-MS and ESI-MS.  

PubMed

A method based on the coupling of high resolution size-exclusion liquid chromatography using a polymer stationary phase with inductively coupled plasma mass spectrometry was developed to study the interactions of two metallodrugs - cisplatin and RAPTA-T - with the serum proteins albumin and transferrin. In contrast to previous approaches, the technique allowed the total recovery of the metals from the column and was able to discriminate between the different species of the metallodrugs and their complexes with the proteins at femtomolar detection levels. Metal binding was found to be dependent on the protein concentration and on the incubation time of the sample. Cisplatin was found to bind the serum proteins to the same extent, whereas RAPTA-T showed marked preference for transferrin. The affinity of the ruthenium complex for holo-transferrin was higher than for the apo-form suggesting a cooperative iron-mediated metal binding mechanism. RAPTA-T binding to holo-transferrin was further investigated by electrospray mass spectrometry using both the intact protein and a model peptide mimicking the iron-binding pocket. PMID:21151827

Groessl, Michael; Terenghi, Mattia; Casini, Angela; Elviri, Lisa; Lobinski, Ryszard; Dyson, Paul J

2010-03-01

225

Superheated high temperature to improve size exclusion chromatography separation of polyethylene glycols with chloroform as the mobile phase.  

PubMed

In our laboratory, chloroform is increasingly required to be used as the mobile phase for the size exclusion chromatography (SEC) characterization of polyethylene glycol (PEG) derivatives, because some of the derivatives show poor solubility in many other solvents. Four types of SEC columns, all based on highly cross-linked polystyrene-polydivinylbenzene (PS/PDB) and compatible with chloroform, have been tried. However, a problem of using chloroform with all the columns tested is that retention might not be rationalized simply based on the SEC-mechanism even for the PEG standards. It was found that for the PEG standards raising the column temperature can significantly improve the SEC separation. In order to take full advantage of the temperature effect on separation, a system was developed which enables the SEC to be performed at superheated temperatures, i.e., temperatures well above the normal boiling point of the mobile phase. The improved SEC separation at elevated temperatures is most likely due to the combination of reduced adsorption of PEGs by the stationary phase and increased solubility of the solutes in the mobile phase. In this work, the SEC separation operated at temperatures above the normal boiling point of the mobile phase was called "superheated high temperature SEC". PMID:22463998

Lou, Xianwen; van Dongen, Joost L J; Meijer, E W

2012-03-14

226

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

227

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

228

Indirect determination of cyanide compounds by ion chromatography with conductivity measurement  

SciTech Connect

Ion chromatography (IC) is a suitable analytical technique for the determination of anions. The cyanide is not detected by the conductivity detector of the ion chromatograph due to its low dissolution constant (pK = 9.2). This paper describes an IC procedure for the determination of free cyanide and metal cyanide complexes that uses a conductivity detector. It is based on the oxidation of cyanide ion by sodium hypochlorite to cyanate ion (pK = 3.66). Therefore, cyanide ion can now be measured indirectly by the conductivity detector. In this procedure, optimum operating conditions were examined. In addition, the interferences from anions and reducing agents were investigated. The method was applied to the determination of metal cyanide complexes. The coefficients of variation (%) for CN/sup -/ (1.05 mg/L), Zn(CN)/sub 4//sup 2 -/ (CN/sup -/, 0.80 mg/L), and Ni(CN)/sub 4//sup 2 -/ (CN/sup -/, 0.96 mg/L) were 1.1%, 1.5%, and 0.5%, respectively. The proposed method proved to be useful for the determination of cyanide compounds in natural water and waste water.

Nonomura, M.

1987-09-01

229

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

230

Differentiation and quantification of linear alkyl benzenesulfonate isomers by liquid chromatography-ion-trap mass spectrometry.  

PubMed

Discrimination and quantitation of the 20 positional isomers of C10-C13 linear alkyl benzenesulfonates (LASs), based on the use of reversed-phase liquid chromatography-electrospray ionisation in negative ion mode ion-trap mass spectrometry, was undertaken. Discrimination was achieved by LAS MS-MS analysis into the ion trap, by monitoring specific fragment ions resulting from the benzylic cleavage of the carbon alkyl chain on both side of the LAS phenyl group. Parameters affecting the electrospray ionisation source and the ion-trap operation were optimised. Calibration curves for the different isomers were established and this permitted their quantitation by mass spectrometry for the first time. MS-MS responses were dependent on both the position of the phenyl group on the alkyl chain and the length of this alkyl chain, these responses being higher for the external isomers and the longer alkyl chain homologues. The precision, expressed as relative standard deviation ranged between 9 and 13%. Detection limits for LAS isomers were between 0.03 and 0.07 mg/l and therefore the method is sensitive enough to be applied to environmental samples. PMID:15058564

Lunar, Loreto; Rubio, Soledad; Pérez-Bendito, Dolores

2004-03-26

231

Separation of strontium-90 and yttrium-90 in the presence of thorium-234 by dynamic ion chromatography  

Microsoft Academic Search

A relatively rapid (90Sr and 90Y in the presence of 234Th. The method joins ion-chromatography and on-line scintillation detection. Experiments were performed to characterize separation of the three radionuclides in an Ion Pac CS5 ion-exchange column under the influence of the following eluents: oxalic acid, diglycolic acid (DGA), -hydroxy isobuteric acid (HIBA), and a mixture of hydrochloric acid and ammonium

E. H. Borai; E. A. El-Sofany

2004-01-01

232

Separation of strontium-90 and yttrium-90 in the presence of thorium-234 by dynamic ion chromatography  

Microsoft Academic Search

A relatively rapid (90Sr and 90Y in the presence of 234Th. The method joins ion-chromatography and on-line scintillation detection. Experiments were performed to characterize separation\\u000a of the three radionuclides in an Ion Pac CS5 ion-exchange column under the influence of the following eluents: oxalic acid,\\u000a diglycolic acid (DGA), ?-hydroxy isobuteric acid (HIBA), and a mixture of hydrochloric acid and ammonium

E. H. Borai; E. A. El-Sofany

2004-01-01

233

A Method of Correcting for Flow-Rate Fluctuations in Size Exclusion Chromatography Calculations: Applications to Methylene Chloride\\/Hexafluoroisopropanol Solvent System  

Microsoft Academic Search

The mixture of methylene chloride\\/hexafluoroisopropanol (70\\/30, v\\/v) is an excellent polyester solvent, but its low boiling point causes unstable flow when it is used for size exclusion chromatography (SEC). In high-performance SEC experiments, retention time is normally used to measure elution volume; however, unstable flow makes it difficult to calibrate an SEC column set or calculate molecular weight parameters from

Bruce L. Neff; J. R. Overton

1984-01-01

234

Salt effect on size-exclusion chromatography of partially sulfonated alternating copolymers of maleic acid and styrene in a polar solvent  

Microsoft Academic Search

The molecular mass distributions of poly[(maleic acid)-alt-styrene] (SMA) and poly[(maleic acid)-alt-(p-sulfostyrene, styrene)] (SSMA) were measured by size-exclusion chromatography (SEC) in N,N-dimethylformamide (DMF) and in DMF containing different amounts of LiBr. The degree of sulfonation of SSMA varies from 18.3 mol% (SSMA I), to 44.8 mol% (SSMA II) and to 83 mol% (SSMA III). Measurements were made at 40°C using a

N. Šegudovi?; S. Serti?; M. Kova?-Filipovi?; V. Jarm

1995-01-01

235

Preparation and application of silica-based perfusion packing of size exclusion chromatography for quantitation of polyacrylamide in enhanced oil recovery systems  

Microsoft Academic Search

The synthesis and characterization of a novel macroporous silica derived size exclusion chromatography (SEC) packing for quantitative\\u000a analysis of high molecular weight (MW) polyacrylamide (PAM) are presented. Using this packing, a fast, sensitive and reproducible\\u000a approach for quantitation of super high-MW PAM in demanding enhanced oil recovery (EOR) waters was developed and the effect\\u000a of synthesis parameters on the properties

Sui Xihua; Zha Qingfang; Wu Mingbo; Guo Yansheng

2007-01-01

236

Fractionation of phosphorus and trace elements species in soybean flour and common white bean seeds by size exclusion chromatography–inductively coupled plasma mass spectrometry  

Microsoft Academic Search

Soluble species of phosphorus, sulfur, selenium and eight metals (Mn, Fe, Co, Ni, Cu, Zn, Mo and Cd) in soybean flour and common white bean seeds were investigated by size exclusion chromatography (SEC) and inductively coupled plasma mass spectrometry (ICP-MS). Samples were extracted by 0.02 mol l?1 Tris–HCl buffer solution (pH 7.5). Fractionation of sample extracts by preparative scale SEC

Richard Kopl??k; Hana Pavelková; Jana Cincibuchová; Oto Mestek; František Kvasni?ka; Miloslav Suchánek

2002-01-01

237

Distribution analysis of ultra-high molecular mass poly(ethylene oxide) containing silica particles by size-exclusion chromatography with dual light-scattering and refractometric detection  

Microsoft Academic Search

Two different size-exclusion chromatography (SEC) systems, connected in-line either to a low-angle light scattering (LALS) or to a multi-angle light scattering (MALS) detector, are employed for determination of molecular mass distributions (MMD) of poly(ethylene oxide) (PEO) samples having a weight average molecular mass up to eight millions. The detrimental effect of the presence of strongly scattering silica particles in the

Bed?ich Porsch; Anette Welinder; Anna Körner; Bengt Wittgren

2005-01-01

238

Continuous measurement of macronutrient ions in the transpiration stream of intact plants using the meadow spittlebug coupled with ion chromatography.  

PubMed

A method is described for continuous, nondestructive analysis of xylem-borne mineral nutrients in intact transpiring plants. The method uses the xylem-feeding insect the meadow spittlebug (Philaenus spumarius L. [Homoptera: Cercopidae]). This insect will feed from a wide range of plant species and organs. Insect excreta can be collected at all times of the day and night, and its mineral ion content can be analyzed rapidly, and without purification, by ion chromatography. The excreta will have a mineral content virtually identical to that of xylem sap. Cages suitable for containing the insects and collecting excreta from any desired location on plants in both laboratory and greenhouse are described. Even in the greenhouse, evaporation had only a minor effect on the sample ion content. Example results are presented which illustrate dynamics, over several days, in the xylem concentrations of sodium (Na(+)), potassium (K(+)), NH(4)(+), magnesium (Mg(2+)), calcium (Ca(2+)), chloride (Cl(-)), NO(3)(-), PO(4)(3-), and SO(4)(2-). These data were collected from young plants growing in pots of compost in the laboratory and from fully mature pepper (Capsicum annuum L. cv Bellboy) plants growing in hydroponics (rockwool) in the greenhouse. This method should facilitate studies of macronutrient uptake and transport in a range of plants and environments. PMID:12428008

Malone, Michael; Herron, Michelle; Morales, M-Angeles

2002-11-01

239

Determination of inorganic corrosion inhibitors in heat transfer systems by ion chromatography.  

PubMed

In water-based heating and cooling circuits monoethylene glycol is frequently used as an anti-freezing agent. For corrosion protection inhibitors based on nitrite, molybdate or amines are commonly added. The determination of nitrite is usually performed by ion chromatography (IC) using an IonPac AS14 analytical column for the anion separation and a suppressed conductivity detection. Local overheating in some circuits causes degradation of ethylene glycol and leads to the formation of some organic acids. Under such chemical conditions the correct quantification of nitrite becomes a more complex analytical task due to the interference of the organic acids. This problem was solved using the IonPac AS9-HC separation column. In heat transfer systems, where nitrite is not stable, molybdate can be used as an inhibitor for corrosion protection. In these cases photometric methods are recommended for monitoring the molybdate concentration. However, due to the dark brown colour and turbidity of aged glycol solutions photometric methods were not applicable. Thus the use of IC offered a reliable alternative for the determination of molybdate, also in aged glycol solutions, using IonPac AS9-HC or AS14 columns for separation. PMID:12830903

Kadnar, Rainer; Madera, Martin; Schlifke, Ruth

2003-05-16

240

Isolation of bile acid glucosides and N-acetylglucosaminides from human urine by ion-exchange chromatography and reversed-phase high-performance liquid chromatography.  

PubMed

A method for the isolation, separation and analysis of glucosides and N-acetylglucosaminides of non-amidated bile acids and of glycine- and taurine-conjugated bile acid glucosides from normal human urine is described. Total bile acids were extracted from 24-h collections of urine by repetitive use of Sep-Pak C18 cartridges. After elution with 80% aqueous methanol, a group separation into non-amidated, glycine- and taurine-conjugated bile acids was performed by ion-exchange chromatography on Lipidex-DEAP. The glycosylated compounds were then separated from the corresponding non-glycosylated ones by high-performance liquid chromatography (HPLC) using a reversed-phase system with a linear methanol gradient. The glycosylated compounds isolated by HPLC were analysed by fast atom bombardment mass spectrometry and, after derivatization, by gas chromatography-mass spectrometry. Information about the sugar moieties of the bile acid glycosides was also obtained by treatment with different glycosidases. PMID:3243856

Marschall, H U; Green, G; Egestad, B; Sjövall, J

1988-10-28

241

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

242

Robust phosphoproteome enrichment using monodisperse microsphere-based immobilized titanium (IV) ion affinity chromatography.  

PubMed

Mass spectrometry (MS)-based proteomics has become the preferred tool for the analysis of protein phosphorylation. To be successful at such an endeavor, there is a requirement for an efficient enrichment of phosphopeptides. This is necessary because of the substoichiometric nature of phosphorylation at a given site and the complexity of the cell. Recently, new alternative materials have emerged that allow excellent and robust enrichment of phosphopeptides. These monodisperse microsphere-based immobilized metal ion affinity chromatography (IMAC) resins incorporate a flexible linker terminated with phosphonate groups that chelate either zirconium or titanium ions. The chelated zirconium or titanium ions bind specifically to phosphopeptides, with an affinity that is similar to that of other widely used metal oxide affinity chromatography materials (typically TiO(2)). Here we present a detailed protocol for the preparation of monodisperse microsphere-based Ti(4+)-IMAC adsorbents and the subsequent enrichment process. Furthermore, we discuss general pitfalls and crucial steps in the preparation of phosphoproteomics samples before enrichment and, just as importantly, in the subsequent mass spectrometric analysis. Key points such as lysis, preparation of the chromatographic system for analysis and the most appropriate methods for sequencing phosphopeptides are discussed. Bioinformatics analysis specifically relating to site localization is also addressed. Finally, we demonstrate how the protocols provided are appropriate for both single-protein analysis and the screening of entire phosphoproteomes. It takes ?2 weeks to complete the protocol: 1 week to prepare the Ti(4+)-IMAC material, 2 d for sample preparation, 3 d for MS analysis of the enriched sample and 2 d for data analysis. PMID:23391890

Zhou, Houjiang; Ye, Mingliang; Dong, Jing; Corradini, Eleonora; Cristobal, Alba; Heck, Albert J R; Zou, Hanfa; Mohammed, Shabaz

2013-02-07

243

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

2013-06-20

244

Assessment of immunoglobulin concentrates on thrombogenic activity by thrombin generation assay, prekallikrein activator assay, and size-exclusion chromatography.  

PubMed

BACKGROUND: Immunoglobulin G (IgG) concentrates have recently been found to be contaminated with procoagulant impurities causing thromboembolic events (TEEs) in vivo. In this study the question was raised whether a thrombin generation assay (TGA) will be able to characterize IgG samples from the Austrian market with regard to their thrombogenic potential. STUDY DESIGN AND METHODS: A total of 44?IgG concentrates have been assayed by TGA employing pooled normal plasma and Factor (F)XI-deficient plasma (FXIdp). Furthermore, the prekallikrein activator assay including determination of blank values, size-exclusion chromatography, and further test systems required for batch release testing of IgG concentrates according to the European Pharmacopeia (Pharm. Eur.) were carried out. RESULTS: All samples complied with acceptance criteria stated in the Plarm. Eur. and/or prescribed by the marketing approval. One intravenous immunoglobulin (IVIG) involved in TEEs exceeded a threshold level of 350?nmol peak thrombin, which was not exceeded after change of manufacture and by all the other IVIGs tested. Two hyperimmune globulins revealed elevated peak thrombin levels of up to 810?nmol in FXI and up to 285?nmol in FXIdp. CONCLUSION: The study indicates that the TGA is able to reliably predict procoagulant activities probably associated with the presence of FXIa and potential thrombogenicity. Comparison of thrombin generation with product-specific acceptance criteria as well as variables from other test systems as amidolytic activity and molecular size can help to monitor IgG quality and manufacturing changes with regard to thrombogenicity. PMID:23772713

Seifner, Alexandra; Beck, Gerhard; Bayer, Patrick; Eichmeir, Stephanie; Lackner, Friedrich; Rögelsperger, Olga; Weber, Katharina; Wollein, Gabriele

2013-06-17

245

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

246

Size and conformation of Ficoll as determined by size-exclusion chromatography followed by multiangle light scattering.  

PubMed

The characteristics of the glomerular filtration barrier (GFB) are challenging to measure, as macromolecular solutes in blood may be metabolized or transported by various cells in the kidney. Urinary solute concentrations generally reflect the cumulative influence of multiple transport processes rather than the intrinsic behavior of the GFB alone. Synthetic tracer molecules which are not secreted, absorbed, or modified by the kidney are useful tools. Ficoll, a globular polymer of epichlorohydrin and sucrose, is round, physiologically inert, and easily labeled, making it a nearly ideal glomerular probe. Fissell et al. reported filtration data suggesting that Ficoll was not as spherical as had been previously suggested (Fissell WH, Manley S, Dubnisheva A, Glass J, Magistrelli J, Eldridge AN, Fleischman AJ, Zydney AL, Roy S. Am J Physiol Renal Physiol 293: F1209-F1213, 2007). More recently, two investigators published comparisons of neutral and anionic Ficoll clearance that suggest Ficoll may undergo conformational changes when chemically derivatized (Asgeirsson D, Venturoli D, Rippe B, Rippe C. Am J Physiol Renal Physiol 291: F1083-F1089, 2006; Guimaraes MAM, Nikolovski J, Pratt LM, Greive K, Comper WD. Am J Physiol Renal Physiol 285: F1118-F1124, 2003). To investigate Ficoll's characteristics further, we examined two commercial preparations, Ficoll 70 and Ficoll 400, by size-exclusion chromatography using a differential refractive index detector combined with light-scattering and viscosity detectors. A slope of 0.45 was obtained from the plot of the logarithm of molecular mass against the logarithm of root-mean square radius. The Mark-Houwink exponent values of 0.34 and 0.36 were calculated for Ficoll 70 and Ficoll 400, respectively. These results suggest Ficoll's conformation in physiological saline solution is likely intermediate between a solid sphere and a well-solvated linear random coil. The measurements help explain our previous observations and guide interpretation of in vivo experiments. PMID:19846572

Fissell, William H; Hofmann, Christina L; Smith, Ross; Chen, Michelle H

2009-10-21

247

Toward reading the sequence of short oligonucleotides from their retention factors obtained by means of hydrophilic interaction chromatography and ion-interaction reversed-phase liquid chromatography.  

PubMed

Retention characteristics of selected synthetic 5'-terminal phosphate absent penta-nucleotides containing adenine, guanine, and thymine were studied in relation to their sequence by hydrophilic interaction chromatography and ion-interaction reversed-phase liquid chromatography. The organic solvent content, pH, and buffer concentration in mobile phases were evaluated as influential separation conditions. Data demonstrate that both compared chromatographic modes can be used to separate synthetic penta-nucleotides according to their nucleotide composition. Moreover, reversed-phase liquid chromatography allows separation according to their sequence. We have found a simple linear additive model to describe the retention order in both separation modes in regard to their sequence. In hydrophilic interaction chromatography, the retention behavior is controlled primarily by the hydrophilicity of involved nucleotides and minimally by their sequence position. For reversed-phase liquid chromatography, the nucleotide hydrophobicity plays an important role in their retention properties and the influence of their location in sequence on the retention increases toward the center and decreases toward the termini. Our results show that the penta-nucleotide sequence, and thus its spatial arrangement induced by the surrounding environment, is highly related to the retention properties, so it may be hypothetically used to read the sequence from the retention properties acquired under particular separation conditions. PMID:23175142

Bittová, Miroslava; Havliš, Jan; Fuksová, Hana; Vrbková, Blanka; Trnková, Libuše

2012-11-01

248

[Determination of organic acids and inorganic anions by gradient ion chromatography].  

PubMed

The chromatographic conditions for separation and detection of organic acids and inorganic anions by gradient ion chromatography with suppressed conductivity detection were studied. The optimized gradient programs were established. Ion chromatography were performed with a DX-100 chromatograph (DIONEX). The separation column is IonPac-AS11. Compared with NaHCO3/Na2CO3 and Na2B4O7, NaOH was the optimal eluent. The effect of organic modifier was also studied. Among methanol, 2-propanol and acetonitrile, methanol can make ion pairs such as malate and succinate, malonate and tartrate gaining baseline resolution. By using ion exchange separation, Cl-, NO3-, malate, succinate, malonate, tartrate, SO4(2-), oxalate were eluted between 5 mmol/L NaOH-16% CH3OH and 10 mmol/L NaOH-16% CH3OH in 25 min. A mobile phase composed of 30 mmol/L NaOH, 50% CH3OH and D.I. water was chosen to elute two groups of organic acids and inorganic anions: (1) quinate, formate, Cl-, malate, malonate, oxalate, citrate, isocitrate, aconitate; (2) lactate, Cl-, SO4(2-), tartrate, PO4(3-), citrate, isocitrate, aconitate. The detection limits (S/N = 3) were 0.1625 (quinate), 0.0691 (formate), 0.0115 (Cl-), 0.0886 (malate), 0.0591 (malonate), 0.0263 (oxalate), 0.1147 (citrate), 0.2017 (isocitrate), 0.3656 (cis-aconitate), 0.1045 (trans-aconitate), 0.1950 (lactate), 0.0729 (tartrate), 0.0224 (SO4(2-)) and 0.0692 (PO4(3-)) mg/L. The relative standard deviations were lower than 11.9% (n = 7) and the correlation coefficients ranged from 0.9212 for Cl- to 0.9999 for formate. The method was applied to determine the organic acids and inorganic anions of beverages and citric acids fermenting-medium. The results were satisfactory. PMID:15739470

Liu, Z; Liu, K; Shen, D; Song, Q; Mou, S; Feng, Y

1997-07-01

249

Determination of trace sulfides in turbid waters by gas dialysis/ion chromatography  

SciTech Connect

The accuracy of the methylene blue colorimetric procedure for the determination of sulfide in environmental waters and waste waters is influenced by turbidity interferences even after application of recommended pretreatment techniques. The direct analysis of sulfide by ion chromatography (IC), without sample pretreatment, is complicated by field preservation of samples with zinc ion (or equivalent). A continuous-flow procedure has been developed that converts the acid-extractable sulfide to H/sub 2/S, which is separated from the sample matrix by a gas dialysis membrane and then trapped in a dilute sodium hydroxide solution. A 200-..mu..L portion of this solution is injected into the ion chromatograph for analysis with an electrochemical detector. Detection limits as low as 1.9 ng/mL have been obtained. Good agreement was found between the gas dialysis/IC and methylene blue methods for nonturbid standards. The addition of ascorbic acid as an antioxidant is required to obtain adequate recoveries from spiked tap and well waters.

Goodwin, L.R.; Francom, D.; Urso, A.; Dieken, F.P.

1988-02-01

250

Determination of lipid-bound sulfate by ion chromatography and its application to quantification of sulfolipids from kidneys of various mammalian species  

Microsoft Academic Search

A variety of procedures have been developed for determining the sulfate ester content of various biomole- cules. Ion chromatography (IC), that is, quantitation of ionic substances by ion conductimetry after separation by anion-exchange chromatography, has been increasingly uti- lized for the determination of inorganic sulfate in clinical and environmental samples. We adopted suppressed-mode IC to the determination of lipid- or

Keiko Tadano-Aritomi; Toshiyuki Hikita; Atsushi Suzuki; Hidenao Toyoda; Toshihiko Toida; Toshio Imanari; Ineo Ishizuka

251

Determination of rare-earth elements in rock samples by an improved high-performance ion chromatography  

Microsoft Academic Search

An analytical technique of rare-earth elements (REE) in rock samples using a high-performance ion chromatography (HPIC) is described. The REE in rock samples were separated from other elements using a conventional ion-exchange column, and then measured by the HPIC. ? -hydroxyisobutyric acid and Arsenazo III were used for eluants and a post-column reagent for the HPIC, respectively. The use of

TSUYOSHI ISHIKAWA; KENJI SUGIMOTO; KAZUYA NAGAISHI

252

Application of silver ion in the separation of macrolide antibiotic components by high-speed counter-current chromatography  

Microsoft Academic Search

Three macrolide antibiotic components – ascomycin, tacrolimus and dihydrotacrolimus – were separated and purified by silver ion high-speed counter-current chromatography (HSCCC). The solvent system consisted of n-hexane–tert-butyl methyl ether–methanol–water (1:3:6:5, v\\/v) and silver nitrate (0.10mol\\/l). The silver ion acted as a ?-complexing agent with tacrolimus because of its extra side double bond compared with ascomycin and dihydrotacrolimus. This complexation modified

Yaoming Wen; Jiaoyan Wang; Xiuming Chen; Zhanxian Le; Yuxiang Chen; Wei Zheng

2009-01-01

253

Selection of pH-related parameters in ion-exchange chromatography using pH-gradient operations  

Microsoft Academic Search

This work demonstrates that the type of ion-exchanger (anion or cation), the mode of operation (bind-and-elute or flow-through), and the operational pH of ion-exchange chromatography (IEX) can be selected in a fast and rational way by analytical pH-gradient IEX operations, thereby eliminating the need for pH scouting or high-throughput screening. The developed approach was applied for the selection of an

Tangir Ahamed; Sreekanth Chilamkurthi; Beckley K. Nfor; Peter D. E. M. Verhaert; Gijs W. K. van Dedem; Luuk A. M. van der Wielen; Michel H. M. Eppink; Emile J. A. X. van de Sandt; Marcel Ottens

2008-01-01

254

Determination of sodium at low ng\\/l concentrations in simulated power plant waters by ion chromatography  

Microsoft Academic Search

The determination of low ng\\/l sodium in the power industry is critical in identifying and preventing corrosive conditions in many power plant components. To address this challenge, we developed an ion chromatographic method to determine sodium at ng\\/l concentrations in power plant samples. The ion chromatography system used on-line electrolytic eluent generation with a continuously regenerated trap column to minimize

Brian M De Borba; Mark Laikhtman; Jeff S Rohrer

2003-01-01

255

Determination of toluene diisocyanate in synthetic-rubber track by ion chromatography with ultraviolet detection after alkaline suppressor  

Microsoft Academic Search

In the present work, a novel analytical method was proposed for the determination of toluene diisocyanate (TDI) in synthetic-rubber track by ion chromatography (IC) coupled with an ultraviolet detector setting at 212nm. TDI can be hydrolyzed to toluene diamine (TDA) which can be separated by cation-exchange IC easily. The optimum IC separation was performed on an IonPac CS12A column (150mm×4.0mm)

Mei Lan Chen; Yun Chang Fan; Chang An Li; Dong Fei; Yan Zhu

2009-01-01

256

Effect of anionic ion-pairing reagent hydrophobicity on selectivity of peptide separations by reversed-phase liquid chromatography  

Microsoft Academic Search

Despite the continuing dominance of trifluoroacetic acid (TFA) as the anionic ion-pairing reagent of choice for peptide separations by reversed-phase high-performance liquid chromatography (RP-HPLC), we believe that a step-by-step approach to re-examining the relative efficacy of TFA compared to other ion-pairing reagents is worthwhile, particularly for the design of separation protocols for complex peptide mixtures, e.g., in proteomics applications. Thus,

M. Shibue; C. T. Mant; R. S. Hodges

2005-01-01

257

Analysis of perchlorate in human urine using ion chromatography and electrospray tandem mass spectrometry.  

PubMed

Because of health concerns surrounding widespread exposure to perchlorate, we developed a sensitive and selective method for quantifying perchlorate in human urine using ion chromatography coupled with electrospray ionization tandem mass spectrometry. Perchlorate was quantified using a stable isotope-labeled internal standard ((18)O(4)-perchlorate) with excellent assay precision (coefficient of variation <5% for repetitively analyzed quality control material). Analytical accuracy was established by blind analysis of certified proficiency testing materials prepared in synthetic urine matrix; calculated amounts deviated minimally from true amounts, with percent differences ranging from 2% to 5%. Selective chromatography and tandem mass spectrometry reduced the need for sample cleanup, resulting in a rugged and rapid method capable of routinely analyzing 75 samples/day. The lowest reportable level (0.025 ng/mL) was sufficiently sensitive to detect perchlorate in all human urine samples evaluated to date, with a linear response range from 0.025 to 100 ng/mL. This selective, sensitive, and rapid method will help elucidate any potential associations between human exposure to low levels of perchlorate and adverse health effects. PMID:15828783

Valentín-Blasini, Liza; Mauldin, Joshua P; Maple, David; Blount, Benjamin C

2005-04-15

258

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

259

Using gas chromatography with ion mobility spectrometry to resolve explosive compounds in the presence of interferents.  

PubMed

Ion mobility spectrometry (IMS) is a valued field detection technology because of its speed and high sensitivity, but IMS cannot easily resolve analytes of interest within mixtures. Coupling gas chromatography (GC) to IMS adds a separation capability to resolve complex matrices. A GC-IONSCAN® operated in IMS and GC? IMS modes was evaluated with combinations of five explosives and four interferents. In 100 explosive/interferent combinations, IMS yielded 21 false positives while GC? IMS substantially reduced the occurrence of false positives to one. In addition, the results indicate that through redesign or modification of the preconcentrator there would be significant advantages to using GC? IMS, such as enhancement of the linear dynamic range (LDR) in some situations. By balancing sensitivity with LDR, GC? IMS could prove to be a very advantageous tool when addressing real world complex mixture situations. PMID:20735708

Cook, Greg W; LaPuma, Peter T; Hook, Gary L; Eckenrode, Brian A

2010-11-01

260

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

2013-01-25

261

Determination of hippuric acid in human urine by ion chromatography with conductivity detection.  

PubMed

A simple, rapid, precise and eco-friendly ion chromatography (IC) method for the determination of hippuric acid (HA) in human urine was proposed in this paper. The separation was carried out an anion exchange column with 2.0 mmol L?¹ Na?CO? + 2.0 mmol L?¹ NaHCO? as mobile phase at the flow-rate 0.7 mL min?¹. A suppressed conductivity detector was used and the detection limit was 1.0 ?g L?¹ (S/N=3) for hippuric acid. The analysis time for one run was 30 min under the optimized IC condition. The recovery of hippuric acid was 93.2-98.0% while the relative standard deviation (RSD) was 1.4-2.3% by seven measurements. PMID:21236740

Zhao, Fuyong; Wang, Zonghua; Wang, Hui; Ding, Mingyu

2010-12-28

262

[Determination of anions in the products of ozonation of reactive dye by ion chromatography].  

PubMed

A method for the determination of anions in the degradation products of C. I. Reactive Red 120 by ozonation was investigated. The sample can be pretreated with a Dionex OnGuard P column, which has high selectivity for removing phenols, azo group-contaning compounds, aromatic carboxylic aicds etc. For the separation of organic and inorganic anions in the products, the anion exchange chromatograhy with gradient elution of NaOH was used. All the species were detected by both suppressed conductivity and UV absorbance detectors. The sulfate, oxalate, chloride, nitrate and formate could be identified even in very low concentration with ion chromatography, within 18 min, with the recoveries between 91.6% - 108.3%. The results indicate that the method is reliable, simple, rapid and especially sensitive. In combining with the determination results of conventional parameters of the solution of Reactive Red 120, a preliminary elucidation of the degradation mechanism PMID:16358701

Zhang, Fei-Fang; Liang, Xin-Miao; Zhang, Qing; Chen, Ji-Ping; Yediler, Ayfer; Kettrup, Antonius

2002-09-01

263

Measurement of conjugated bile acids by ion-pair high-performance liquid chromatography.  

PubMed

Vhe quantitatively most important conjugated bile acids in man were separated by reversed-phase ion-pair chromatography without prior derivatization. As non-polar matrix an Ultrasphere I.P. column (C18) was used, and an ionic alkyl compound, tetrabutylammonium phosphate, was added to the mobile phase, which was a mixture of acetonitrile and water. Under these conditions, the glycine and taurine conjugates of cholic acid, chenodeoxycholic acid and deoxycholic acid were separated within 15 min. At 214 nm, the minimum measurable concentration was 1.3-2.0 nmol/ml. The average recovery from bile was 94%. In ten patients with biliary drainage an average of 79.5% of the bile acids were glycine conjugates. PMID:6674317

Wildgrube, H J; Füssel, U; Lauer, H; Stockhausen, H

1983-12-30

264

DIONEX ICS3000 ION CHROMATOGRAPHY SYSTEM INSTALLATION AND INSTRUMENT ASSESSMENT FOR SRNL APPLICATIONS  

SciTech Connect

Ion Chromatography (IC) is routinely used at the Savannah River National Laboratory (SRNL) for sample analysis and characterization. Results from IC analysis are valued in corrosion control maintenance and measurement programs, remediation waste process control, soil and ground water measurement, nuclear materials processing, and various other research and development programs. Presented in this report are analytical methods developed on a DIONEX ICS3000 Reagent Free Ion Chromatography (RFIC) system located in AD at SRNL. This IC system contains two independent analysis channels comprising of a mobile phase generator, a pump, stationary phase columns, a suppressor and a conductivity detector. One channel is dedicated to anion analysis using Potassium Hydroxide (KOH) as the mobile phase while a second channel is configured for cation analysis using Methanesulfonic Acid (MSA) as the mobile phase. Both channels share an autosampler and the peak analysis software, Chromeleon{reg_sign} v.6.8. Instrument configuration is modified from the manufacturer for radiological service. Listed within this report are Dionex ICS3000 parameters and results for the analysis of routine anions and cations. Additional method parameters and discussion are presented on the analysis of Acetate (CH{sub 3}COO{sup -}) and Iodate (IO{sub 3}{sup -}). Previous IC analysis instruments at AD have been based upon carbonate/bicarbonate buffer mobile phase chemistry. This report represents a transition to hydroxide as a mobile phase eluent. The hydroxide eluent offers a lower baseline conductivity, which allows for greater sample dilution and/or lower detection limits. Also the hydroxide mobile phase and column set has a significant separation of the phosphate peak from the nitrate and sulfate peaks vs. the carbonate/bicarbonate mobile phase and column set, an advantage for the industrial waste analyzed at SRNL.

Wiedenman, B.; White, T.

2009-11-16

265

Determination of sulfide in brain tissue by gas\\/dialysis\\/ion chromatography: Postmortem studies and two case reports  

Microsoft Academic Search

An analytical method for the determination of sulfide in human and rat brain is described. It utilizes a continuous flow gas dialysis pretreatment and quantitation by ion chromatography with electrochemical detection. Rat brain sulfide levels were reliably measured after fatal intoxication by intraperitoneal injection of NaHS. By expeditious analysis of samples it was possible to demonstrate the presence of endogenous

L. R. Goodwin; D. Francom; F. P. Dieken; J. D. Taylor; M. W. Warenycia; R. J. Reiffenstein; G. Dowling

2009-01-01

266

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

267

Isolation and Identification of Drugs of Forensic Interest by High Performance Reverse Phase Ion Pair Partition Chromatography  

Microsoft Academic Search

A method is presented for the isolation and identification of milligram or microgram quantities of drugs of forensic interest. High performance reverse phase ion pair partition chromatography is performed on a 9.4 millimeter internal diameter microparticulate octadecylsilane column employing a water, methanol, acetic acid, alkylsulfonate mobile phase. Subsequent to collection from the liquid chromatograph, a simple extraction is performed followed

Ira S. Lurie; Jeffrey M. Weber

1978-01-01

268

Determination of Methylamines and Trimethylamine-N-oxide in particulate matter by non-suppressed ion chromatography  

Technology Transfer Automated Retrieval System (TEKTRAN)

An ion chromatography method with non-suppressed conductivity detection was developed for the simultaneous determination of methylamines (methylamine, dimethylamine, trimethylamine) and trimethylamine-N-oxide in particulate matter air samples. The analytes were well separated by means of cation-exch...

269

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

270

SPECIATION OF SELENIUM(IV) AND SELENIUM(VI) USING COUPLED ION CHROMATOGRAPHY: HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

A simple method was developed to speciate inorganic selenium in the microgram per liter range using coupled ion chromatography-hydride generation atomic absorption spectrometry. Because of the differences in toxicity and adsorption behavior, determination of the redox states selenite, Se(IV), and s...

271

Hand-Portable Gas Chromatography-Ion Mobility Spectrometer for the Determination of the Freshness of Fish.  

National Technical Information Service (NTIS)

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 discrim...

A. P. Snyder C. S. Harden D. M. Davis D. B. Shoff W. M. Maswadeh

1995-01-01

272

A Simple Ion Exchange Thin Layer Chromatography Method for the Separation of Amino Acids in Clinical Samples  

Microsoft Academic Search

An ion exchange thin layer chromatography method for the separation of 16 amino acids is described. The effect of the pH of buffer on the resolution of the amino acids is discussed. Development in pH 3.3 buffer at 45°C resolved all the amino acids. The method is particularly well adapted to screening metabolic disorders in neonatal children.

Haleem J. Issaq; Tibor Dèvènyi

1981-01-01

273

High Speed Separation and Quantitation of Ralstonia solanacearum of Different Virulences Using High Performance Ion Exchange Chromatography  

Microsoft Academic Search

High performance ion exchange chromatography coupled with laser light scattering instrument was employed for the rapid separation and quantitation of Ralstonia solanacearum of different virulences. The pure culture of Ralstonia solanacearum was successfully separated into three characteristic fractions. Each fraction was collected and inoculated onto 2, 3, 5-triphenyltetrazolium chloride (TTC) plates to identify its virulence. The shapes and colors of

Juan LIN; Cheng MA; Shutao LIU; Lingling WU; Pingfan RAO

2007-01-01

274

Development of ion chromatography methods for the determination of trace anions in ultra pure water from power plants  

Microsoft Academic Search

A suppressed ion chromatography (IC) technique, using a carbonate\\/hy- drogen carbonate or a hydroxide eluent, has been evaluated as a monitoring tool for the detection of major anions (F - ,C l - ,N O3 - ,P O4 3- and SO4 2- ) in ultra pure water and condensed steam from thermal power plants. An electrical conductivity detector with an

Dragana Cickaric; Ivana Dersek-Timotic; Antonije Onjia; Ljubinka Rajakovic

2005-01-01

275

Ion chromatography and on-line scintillation counting for the analysis of non-gamma emitting radionuclides in reactor coolant  

Microsoft Academic Search

The use of ion chromatography and on-line scintillation counting for the measurement of non-gamma emitters was evaluated for its applicability to reactor coolant. Potential chemical and radiological interferences were identified and a procedure was developed to eliminate them. The method was tested on a sample of simulated pressurized water reactor coolant.

R. A. Fjeld; S. Guha; T. A. Devol; J. D. Leyba

1995-01-01

276

Size Exclusion Chromatography System.  

National Technical Information Service (NTIS)

Instrumentation was purchased as planned set up, and used to support the ongoing ARO grant 'Elastomeric Nanocomposites Based On Sol-Gel Reactions of Silicon Alkoxides In lonomeric Derivatives Of Finely-Architectured Block Copolymers'. Research results are...

K. A. Mauritz R. F. Storey

2001-01-01

277

Analysis of protein-protein interaction by simulation of small-zone size exclusion chromatography. Stochastic formulation of kinetic rate contributions to observed high-performance liquid chromatography elution characteristics.  

PubMed Central

High-performance liquid chromatography (HPLC) procedures provide size-exclusion chromatography with sufficient speed that the elution characteristics of mixtures of interacting macromolecules are potentially determined by the kinetics of association and dissociation. However, few studies have yet addressed the consequences of interaction kinetics on HPLC analyses or evaluated the potential application of HPLC methods for the qualitative and quantitative interpretation of macromolecular interaction kinetics. An earlier simulation of small-zone chromatography of interacting molecules (Stevens, F. J. 1986. Biochemistry. 25:981-993) has been modified to incorporate the effects of association/dissociation kinetics on elution behavior. The previous assumption of instantaneous equilibration has been replaced by explicit calculation of partial relaxation of complexed and free constituent mixtures during each iteration of the simulation. In addition, a stochastically based formulation has been introduced to determine a velocity probability distribution that emulates the partial intermixing of free and complexed pools during the iteration cycle. The simulation generates bimodal elution profiles representing stable complexed and free components of mixtures for which interaction is characterized by slow kinetics relative to chromatography run times. For mixtures with rapid kinetics, a single-asymmetric peak results. When tested with a large-zone sample such that a plateau of stable concentration is generated, the simulation reproduces previous characterizations based on evaluations of solute continuity equations. Therefore, HPLC may, in many cases be an appropriate basis for techniques by which to evaluate kinetic and affinity characteristics of interacting biomolecules.

Stevens, F J

1989-01-01

278

Use of ion chromatography for monitoring microbial spoilage in the fruit juice industry.  

PubMed

Fruit juices and purees are defined as fermentable, but unfermented, products obtained by mechanical processing of fresh fruits. The presence of undesired metabolites derived from microbial growth can arise from the use of unsuitable fruit or from defects in the production line or subsequent contamination. This involves a loss in the overall quality that cannot be resolved by thermal treatment following the start of fermentation. With these considerations, together with microbiological control, the analysis of different metabolites, which can be considered as microbial growth markers, such as alcohols (i.e. ethanol, etc.), acids (i.e. acetic, fumaric, lactic, etc.) is fundamental in order to achieve a better evaluation of product quality. Enzymatic determination and other single-component analytical techniques are often used for the determination of these metabolites. When the microbial spoilage is not well known, this results in a long and cumbersome procedure. A versatile technique that is capable of determining many metabolites in one analysis could be helpful in improving routine quality control. For this purpose, an ion chromatographic technique, such as ion exclusion, for separation, and diode array spectrophotometry and conductivity, for detection, were evaluated. Both different industrial samples and inoculated samples were analyzed. PMID:9203364

Trifirò, A; Saccani, G; Gherardi, S; Vicini, E; Spotti, E; Previdi, M P; Ndagijimana, M; Cavalli, S; Reschiotto, C

1997-05-16

279

Insight into the distribution of molecular weights and higher-order structure of hyaluronans and some beta-(1 --> 3)-glucans by size exclusion chromatography.  

PubMed

The effects of high energy ultrasound and slightly raised temperature combined with the denaturing action of dimethylsulphoxide on the molecular weight and higher-order structure of hyaluronans and some beta-(1 --> 3)-glucans were studied by means of size exclusion chromatography (SEC) technique. Some experimental conditions connected with the (bio-)polymer sample preparation prior to its SEC analysis are overviewed in the light of informational relevance of studies where the action of a physical and/or chemical agent changes the hydrodynamic size of the m omolecule. PMID:8924726

Soltés, L; Mislovicová, D; Sébille, B

280

Determination of phosphonates in natural waters by ion-pair high-performance liquid chromatography.  

PubMed

The paper describes a new method for the determination of phosphonates by ion-pair high-performance liquid chromatography. The phosphonates are complexed with Fe(III) and separated on a reversed-phase polymer column. The eluent consists of a bicarbonate solution at pH 8.3, tetrabutylammoniumbromide as counter-ion and 14% acetonitrile. The complexes are detected at 260 nm. The four phosphonates HEDP (1-hydroxyethylene-1,1-diphosphonic acid). ATMP (aminotris [methylenephosphonic acid]), EDTMP [ethylenediaminetetra(methylenephosphonic acid)], and DTPMP [diethylenetriaminepenta (methylenephosphonic acid)] are well separated within 20 min. The limits of detection are 5.10(-8) M for ATMP and EDTMP, 1.10(-7) M for DTPMP and 5.10(-7) M for HEDP. The method is suitable for the determination of phosphonates in the influent and effluent of wastewater treatment plants. A preconcentration of 10 is easily achieved by adsorption of the phosphonates onto freshly precipitated calcium carbonate and subsequent dissolution of the solid-phase by HCl. PMID:9228795

Nowack, B

1997-06-27

281

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

282

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

283

Determination of selenium species in spent oil shale leachates by ion chromatography  

SciTech Connect

The leaching and transport of trace elements from spent oil shales is a growing area for environmental concern. Selenium is often present in spent oil shales. Under the alkaline conditions present in spent western oil shale leachates, selenium species display anionic behavior, increasing their solubility and mobility. The processes that govern the partitioning of selenium species between solid and solution phases are not well understood, and computer modeling is an important tool in this area. The accuracy of geochemical model predictions depends on the thermodynamic data and mathematical formulations used in their development. To assure reliability of model predictions, it is essential to validate ion speciation data obtained from geochemical models with data obtained from laboratory analyses. The purpose of this study was to begin developing a method for the speciation of the two most common selenium species in spent oil shale leachates, selenite (SeO{sub 3}{sup 2{minus}}) and selenate (SeO{sub 4}{sup 2{minus}}), using suppressed ion chromatography. 26 refs., 4 figs., 2 tabs.

Niss, N.D.; Powers, C.R.

1988-09-01

284

Determination of trace levels of bromate in flour and related foods by ion chromatography.  

PubMed

In this paper, a method of determining trace levels of bromate in flour and related foods by ion chromatography with large volume injection has been proposed. The detection of bromate was performed with a suppressed conductivity detector after separation on an IonPac AS19 column with KOH as the gradient eluent. Parameters affecting the extraction efficiency of bromate, such as the flour-to-water ratio, extraction time, and temperature, were studied in detail. The optimized pretreatment process was then selected. By using the large volume injection technique, the solution detection limit was decreased to 0.5 microg/L. The linear range of this method was from 5 to 1000 microg/L, and the linear correlation coefficient was 0.9998. The method has been applied to the detection of bromate in flour and related foods, and different concentration levels of bromate were detected in various samples. The spiked recoveries ranged from 86 to 110%. The relative standard deviation (RSD) of the bromate peak height for the seven successive injections of the flour sample was 6.4%. PMID:16848496

Shi, Yali; Liang, Lina; Cai, Yaqi; Mou, Shifen

2006-07-26

285

Characterization of impurities in tylosin using dual liquid chromatography combined with ion trap mass spectrometry.  

PubMed

Investigation of unknown impurities in a tylosin sample was performed using liquid chromatography coupled to mass spectrometry (LC/MS). Separation was performed according to the recently described LC-UV method of Ashenafi et al. (2011) [14]. This method was reported to have a good selectivity as it was able to separate the four main components of tylosin from the already known and 23 unknown impurities. However, as this method uses a mobile phase with non-volatile constituents, direct characterization of these impurities using LC/MS was not possible. The impurity fractions were therefore first collected and then desalted before sending them to the MS. Identification of the impurities in the tylosin sample was performed with a quadruple ion trap (IT) MS, with an electrospray ionization (ESI) source in the positive ion mode. The structure of the impurities was deduced by comparing their fragmentation pattern with those of the main components of tylosin. As several peaks in the LC-UV method contained multiple compounds, using this method in total 41 new impurities were (partly) characterized. PMID:23598092

Chopra, Shruti; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

2012-12-14

286

Application and validation of ion chromatography for the analysis of power plants water: Analysis of corrosive anions in conditioned water–steam cycles  

Microsoft Academic Search

In this study, the possibility of monitoring ion species that could cause corrosion processes in the thermal power plant (TPP) using suppressed ion chromatography (SIC) was investigated. An ion chromatography method for the determination of target anions at sub-to-low-?g\\/L levels in power plant water samples was developed. In this method, the water samples are injected using the large-loop direct injection

Dragana Z. Živojinovi?; Ljubinka V. Rajakovi?

2011-01-01

287

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

2011-06-06

288

Factors influencing the separation of oligonucleotides using reversed-phase/ion-exchange mixed-mode high performance liquid chromatography columns.  

PubMed

New mixed-mode columns consisting of reversed-phase and ion-exchange separation modes were evaluated for the analysis of short RNA oligonucleotides (?20mers). Conventional analysis for these samples typically involves using two complementary methods: strong anion-exchange liquid chromatography (SAX-LC) for separation based on charge, and ion-pair reversed-phase liquid chromatography (IP-RPLC) for separation based on hydrophobicity. Recently introduced mixed-mode high performance liquid chromatography (HPLC) columns combine both reversed-phase and ion-exchange modes, potentially offering a simpler analysis by combining the benefits of both separation modes into a single method. Analysis of a variety of RNA oligonucleotide samples using three different mixed-mode stationary phases showed some distinct benefits for oligonucleotide separation and analysis. When using these mixed-mode columns with typical IP-RPLC mobile phase conditions, such as ammonium acetate or triethylammonium acetate as the primary ion-pair reagent, the separation was mainly based on the IP-RPLC mode. However, when changing the mobile phase conditions to those more typical for SAX-LC, such as salt gradients with NaCl or NaBr, very different separation patterns were observed due to mixed-mode interactions. In addition, the Scherzo SW-C18 and SM-C18 columns with sodium chloride or sodium bromide salt gradients also showed significant improvements in peak shape. PMID:23859796

Biba, Mirlinda; Jiang, Eileen; Mao, Bing; Zewge, Daniel; Foley, Joe P; Welch, Christopher J

2013-06-27

289

Integrated separation scheme for coal-derived liquids using ion-exchange and adsorption chromatography  

SciTech Connect

A separation scheme for coal-derived liquids has been developed that separates by functionality into discrete compound classes using ion-exchange resins; neutrals are further subdivided into fractions differing in polarity, structure, and molecular weight by adsorption chromatography. Sufficient material can be separated to allow further characterization at both gross structural and molecular levels. It gives excellent overall reproducibility (+/- 4%) and recovery (>97%). Removal of acidic and base species prior to recovery of the liquefaction solvent by distillation is a major advantage of the method because it leads to a reduction both in the loss of lower boiling components and in the potential thermal alteration of the sample. The selectivity and discrimination of the procedure are demonstrated for a Victorian brown coal (Loy Yang field) liquefaction product as shown by spectroscopic and chemical analyses of its major fractions. The use of this method as a chemical probe can facilitate investigation of liquefaction mechanisms by enabling a ready selection for analysis of components varying according to a choice of parameters encompassing functionality, polarity, and structure. 29 references, 7 figures, 5 tables.

Strachan, M.G.; Johns, R.B.

1986-02-01

290

Fabrication of electrolytic cell for online post-column electrochemical derivatization in ion chromatography.  

PubMed

An electrolytic cell (EC), composed of two ruthenium-plated titanium electrodes separated by cation-exchange membranes, was fabricated and evaluated for online postcolumn derivatization in ion chromatography (IC). Folic acid (FA) and methotrexate (MTX) were preliminarily used as prototype analytes to test the performance of EC. After separation by an anion exchange column, FA and MTX, which emit very weak fluorescence when excited, were electrochemically oxidized online in the anode chamber of the EC. The compounds with strong fluorescence, which are oxidation products, were detected by the fluorescence detector. The phosphate buffer solution (100 mM KH(2)PO(4)) served as an optimal eluent for anion exchange chromatographic separation and a suitable supporting electrolyte for electro-oxidation, leading to ideal compatibility between IC separation and the postcolumn electrochemical derivatization. For the presently proposed method, the linear ranges were from 0.01 mg L(-1) to 5 mg L(-1) for both FA and MTX. The detection limits of FA and MTX were 1.8 and 2.1 ?g L(-1), and the relative standard deviations (RSD, n=7) were 2.9% and 3.6%, respectively. The method was applied for the simultaneous determination of FA and MTX in the plasma of patients being treated for rheumatoid arthritis. The determination of MTX in the urine of the patients of diffuse large B cell lymphoma was also demonstrated. PMID:22713918

Wu, Shuchao; Xu, Wei; Yang, Bingcheng; Ye, Mingli; Zhang, Peimin; Shen-Tu, Chao; Zhu, Yan

2012-05-19

291

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

292

Determination of sulfur species in oil shale waste waters by ion chromatography  

SciTech Connect

Ion chromatography was evaluated for analysis of sulfur (S) species in oil shale waste waters. Chromatographic separation of S/sub 2/O/sub 3//sup 2 -/ and SCN/sup -/, the effect of high salt concentration on the elution of SO/sub 4//sup 2 -/, and the inherent instability of S species in the samples are discussed. Several sulfur-oxide anions, including S/sub 2/O/sub 4//sup 2 -/, S/sub 2/O/sub 5//sup 2 -/, S/sub 2/O/sub 6//sup 2 -/, and S/sub 2/O/sub 7//sup 2 -/ were unstable when added to solution, forming SO/sub 3//sup 2 -/, SO/sub 4//sup 2 -/. However the method proved applicable to determination of SO/sub 3//sup 2 -/, SO/sub 4//sup 2 -/, S/sub 2/O/sub 3//sup 2 -/ and SCN/sup -/ in oil shale retort water and from retorted shale in both laboratory and field studies.

McFadden, K. M.; Garland, T. R.

1980-10-01

293

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

294

Speciation of chromium in waste water using ion chromatography inductively coupled plasma mass spectrometry.  

PubMed

Ion chromatography (IC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was systematically investigated for determining the speciation of chromium in environmental samples. Firstly, the stability of complexes formed by Cr(III) with various aminopolycarboxylic acids was studied by electrospray ionization mass spectrometry (ESI-MS). The results showed that [Cr(EDTA)](-) was stable in solution. Secondly, various mobile phases were examined to separate Cl(-) from chromium species by IC to avoid Cl(-) interference. The separation of [Cr(EDTA)](-) and Cr(VI) was achieved on a new anion-exchange column (G3154A/102) using a mobile phase containing 20mM NH(4)NO(3) and 10mM NH(4)H(2)PO(4) at pH 7.0 without Cl(-) interference. Detection limits for chromium species were below 0.2 microg/L with a direct injection of sample and without prior removal of interferences from the matrix. Finally, the proposed method was used for the determination of chromium species in contaminated waters. PMID:19071630

Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2006-11-28

295

Speciation of arsenic by ion chromatography inductively coupled plasma mass spectrometry using ammonium eluents.  

PubMed

A method based on ion chromatography (IC) and inductively coupled plasma MS (ICP-MS) was developed for the speciation of arsenic in water and soil extracts. An anion-exchange column (G3154A/101) was used to separate As(III), As(V), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) with excellent resolution. Various ammonium salts, including NH4H2PO4, (NH4)2HPO4, (NH4)2CO3, and NH4HCO3, were examined as eluents to reduce matrix interference from chloride and to solve clogging problems. The best arsenic speciation was obtained within 9 min with excellent resolution and without interference from high chloride concentrations using an eluent containing 7.5 mM (NH4)2HPO4 at pH 7.9. The detection limits for the target arsenic species ranged from 0.1 to 0.4 microg/L with direct injection of sample without matrix elimination. The proposed method was effectively demonstrated by determining arsenic species in contaminated waters and soils of Bangladesh. PMID:17313108

Chen, ZuLiang; Akter, Kazi Farzana; Rahman, Mohammad Mahmudur; Naidu, Ravendra

2006-11-01

296

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

297

Ion chromatography of azide in pharmaceutical protein samples with high chloride concentration using suppressed conductivity detection.  

PubMed

Methods based on reversed-phase liquid chromatography with UV detection of 4-nitrobenzoyl- or 3,5-dinitrobenzoyl azide derivatives lack in accuracy and stability of derivatives to be applied for azide determination in pharmaceutical protein samples with high sodium chloride concentrations. This paper describes a sensitive and selective ion chromatographic method, with simple sample preparation and suppressed conductivity detection, developed for trace determination of azide in protein samples containing sodium chloride in concentrations as high as 11.6 g L(-1). Anion exchange stationary phase with quaternary alkyl amine functional groups and gradient elution with sodium hydroxide enabled good resolution of anions with similar retention times: azide, bromide and nitrate, as well as chloride whose retention time was shorter than azide's. Anions with high affinity to stationary phase (phosphate and citrate) were also eluted within acceptable analysis time of 32 min. The stability of sample solutions and the method selectivity, accuracy, precision and sensitivity satisfied the validation criteria of international organizations competent for pharmaceutical industry. The detection and quantitation limit ranges of sodium azide in protein samples were 0.007-0.02 mg L(-1) and 0.02-0.06 mg L(-1), respectively. Both limits increased with the concentration of sodium chloride. PMID:18308648

Vinkovi?, Kristinka; Drevenkar, Vlasta

2008-02-07

298

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

2012-12-01

299

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

300

Sequential separation of actinides by ion chromatography coupled with on-line scintillation detection.  

PubMed

The separation and measurement of actinides by ion chromatography (IC) coupled with on-line scintillation detection was investigated. Separation of (237)Np, (239)Pu, (241)Am, (244)Cm, (230)Th, and (233)U was accomplished using a Dionex CG5 guard column, CS5 separation column, and an elution program utilizing oxalic, diglycolic, and nitric acid eluents. Np(V) was eluted as a weak anionic oxalate complex or as free NpO(2)(+) cation, Am(III) and Cm(III) as anionic oxalate complexes, Pu(IV) and Th(IV) as nonionic diglycolate complexes, and U(VI) as a free uranyl cation. Response of the flow-cell detector was linear over the full range of activities tested (4-1500 Bq). The minimum detectable activities for the investigated analytes ranged from 3.6 Bq for (244)Cm to 5.4 Bq for (230)Th and (239)Pu. The corresponding minimum detectable concentrations based on a 1-L sample ranged from 3.6 to 5.4 KBq m(-3) (96 to 150 pCi L(-1)). PMID:12458426

Reboul, Scott H; Borai, Emad H; Fjeld, Robert A

2002-10-16

301

Comparison of the ion exclusion chromatographic method with the Monier-Williams method for determination of total sulfite in foods.  

PubMed

Experimental data comparing the alkali extraction/ion exclusion chromatographic method with the Monier-Williams method for determination of total sulfite are presented in (a) enzymatic and nonenzymatic browning systems, (b) vegetables containing naturally occurring sulfite, and (c) a carbohydrate-type food additive, erythorbic acid. Excellent agreement, with a linear correlation coefficient of 0.99, was observed in fresh potato samples homogenized with sulfite and allowed to react for different time intervals (enzymatic browning system). A good overall correlation was observed in dehydrated, sulfited apple samples heated for different times (nonenzymatic browning system); however, as heating time increased, higher results were obtained by the Monier-Williams method than by the alkali extraction/ion exclusion chromatographic method. The results of determining sulfite in the alkali trapping solution following acid distillation or acid treatment without heat suggested that this deviation was due to a fraction of sulfite bound to the browning reaction products in such a way that it was released by acid distillation but not by alkali extraction or acid treatment without heat. Similar behavior was demonstrated in cabbage with naturally occurring sulfite, which was released by acid distillation but not by alkali extraction or acid treatment without heat. The ion exclusion chromatographic method could overcome interference by the volatile caramelization reaction products in the Monier-Williams determination of erythorbic acid. PMID:2708275

Kim, H J

302

Ion exclusion and electrokinetic effects resulting from electro-osmotic flow of salt solutions in charged silica nanopores.  

PubMed

Silica nanopores are the focus of significant scientific interest due to their potential in a wide variety of applications including desalination membranes. In this paper, the results of extensive all-atom molecular dynamics simulations of the electro-osmotic flow of 0.5 M monovalent (NaCl) and divalent (CaCl(2)) ionic solutions through cylindrical charged silica nanopores are presented. The silica nanopores are produced such that they capture the experimentally observed interfacial properties. The results provide an atomistic description of the ion transport through pores of diameters of 1.5 nm, 2.0 nm, 2.5 nm and 3.0 nm. In doing so, the effect of pore size on ion pairing, ion hydration, and water orientation for each ionic solution was investigated. Also, the transport of the ions through the nanopores is studied, and it is found that in the monovalent solutions the Cl(-) ions are excluded from the nanopores of all sizes. Whereas in the divalent solutions, there is no such preferential exclusion of either ion. This is due to the fact that the interfacial charge is fully compensated for by the Ca(2+) ions while it is not the case for the Na(+) ions. PMID:22441317

Haria, Neil R; Lorenz, Christian D

2012-03-22

303

Determination of oxybutinin chloride in pharmaceuticals by reversed-phase ion-pair liquid chromatography with two counter-ions in the eluent.  

PubMed

A reliable stability-indicating method using reversed-phase ion-pair high-performance liquid chromatography for the determination of the anticholinergic drug oxybutinin chloride in pharmaceuticals is reported. Sample extraction is easy and fairly rapid and recovery and precision of the method are excellent. Due to the simultaneous use of an organic amine and of an alkanesulphonate in the mobile phase, good selectivity towards related (quaternary ammonium) anticholinergic drugs was obtained. PMID:3241019

De Schutter, J A; De Moerloose, P

1988-10-26

304

Simultaneous Determination of Transition and Rare Earth Metal Ions in Nd-Fe-B Material by High Performance Ion Chromatography Using Post-Column Chelation Technique  

Microsoft Academic Search

The transition and lanthanide metal ions of Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in Neodymium-iron-boron (Nd-Fe-B) magnetic material are separated and determined by high performance ion chromatography (HPIC) with spectrophotometric detection using post-column reaction methods. 4-(2-pyridylazo)resorcinol (PAR) and 2-(1,8-dihydroxy-3,6-disulfo-2-naphthylazo)benzenearsonic acid (Arsenazo-III) are used

Rajananda Saraswati

1993-01-01

305

Accurate mass filtering of ion chromatograms for metabolite identification using a unit mass resolution liquid chromatography\\/mass spectrometry system  

Microsoft Academic Search

Acceleration of liquid chromatography\\/mass spectrometric (LC\\/MS) analysis for metabolite identi- fication critically relies on effective data processing since the rate of data acquisition is much faster than the rate of data mining. The rapid and accurate identification of metabolite peaks from complex LC\\/MS data is a key component to speeding up the process. Current approaches routinely use selected ion chromatograms

Ming Gu; Yongdong Wang; Xian-guo Zhao; Zhe-Ming Gu

2006-01-01

306

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

307

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

308

Effects of eluent composition, ion-pair reagent and temperature on the separation of histones by high performance liquid chromatography  

Microsoft Academic Search

The influence of the eluent composition, ion-pair concentration, and temperature on the fractionation of chromosomal proteins by reversed-phase high performance liquid chromatography (HPLC) has been investigated. Based on this examination methods for the troublesome separation of histones H1o\\/H1b, H2A\\/H4, and H5.1\\/H5.2 have been developed.

H. Lindner; W. Helliger

1990-01-01

309

Simultaneous determination of trace level bromate and chlorinated haloacetic acids in bottled drinking water by ion chromatography  

Microsoft Academic Search

A convenient and sensitive method for the simultaneous determination of trace level of bromate and chlorinated haloacetic acids in bottled drinking water with ion chromatography is presented. With a high capacity anion-exchange column and 11.5 mmol\\/l Na2CO3 eluent, all the 16 analytes could be separated in one injection within 31 min. By employing a microwave based evaporation technique, the bottled

Yongjian Liu; Shifen Mou

2003-01-01

310

Analysis of the monoenoic fatty acid distribution in hydrogenated vegetable oils by silver-ion high-performance liquid chromatography  

Microsoft Academic Search

A silver-ion high-performance liquid chromatography column (hexane\\/acetonitrile as solvent, ultraviolet detection) was used\\u000a to analyze the fatty acid distribution (as fatty acid methyl esters) of a representative sample of hydrogenated oil. Fractions\\u000a containingcis- andtrans-18:1 isomers were readily separated. The positional fatty acid isomers were separated by rechromatographing these fractions.\\u000a The elution order and percent compositions were compared with results obtained

R. O. Adlof; L. C. Copes; E. A. Emken

1995-01-01

311

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

Microsoft Academic Search

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

Michael J. Ford; Gary J. Van Berkel

2004-01-01

312

Histidines in affinity tags and surface clusters for immobilized metal-ion affinity chromatography of trimeric tumor necrosis factor ?  

Microsoft Academic Search

In order to achieve efficient IMAC (immobilized metal-ion affinity chromatography) purification of tumor necrosis factor ? (TNF-?) and its analogs by a common chromatographic procedure, we tested four histidine-rich affinity tags attached to the N-termini of the trimeric TNF-? molecule. Using low cultivation temperature and appropriate protease deficient E. coli strains, it was possible to obtain intact, full-length proteins with

V Gaberc-Porekar; V Menart; S Jevševar; A Videnšek; A Štalc

1999-01-01

313

Determination of strontium-90 in milk samples using a controlled precipitation clean-up step prior to ion-chromatography  

Microsoft Academic Search

Strontium-90 may be determined by ?-counting its yttrium-90 daughter following separation by ion-chromatography, using a three column system comprising a chelating concentrator column, a cation-exchange column and an anion-exchange separator column. The column system has previously been applied to the determination of strontium-90 in water and urine samples. The applicability of the system to the analysis of milk is hampered

J. Cobb; P. Warwick; R. C. Carpenter; R. T. Morrison

1995-01-01

314

Separation of polar betalain pigments from cacti fruits of Hylocereus polyrhizus by ion-pair high-speed countercurrent chromatography  

Microsoft Academic Search

Polar betacyanin pigments together with betaxanthins from ripe cactus fruits of Hylocereus polyrhizus (Cactaceae) were fractionated by means of preparative ion-pair high-speed countercurrent chromatography (IP-HSCCC) also using the elution–extrusion (EE) approach for a complete pigment recovery. HSCCC separations were operated in the classical ‘head-to-tail’ mode with an aqueous mobile phase. Different CCC solvent systems were evaluated in respect of influence

S?awomir Wybraniec; Pawe? Stalica; Gerold Jerz; Bettina Klose; Nadine Gebers; Peter Winterhalter; Aneta Spórna; Maciej Szaleniec; Yosef Mizrahi

2009-01-01

315

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

316

Isolation and mass spectrometry characterization of molecular species of lactosylceramides using liquid chromatography-electrospray ion trap mass spectrometry  

Microsoft Academic Search

Reverse-phase liquid chromatography\\/electrospray ion trap mass spectrometry (LC-ESI-MSn) was established for identification of the molecular species of lactosylceramides. Lactosylceramides derived from porcine blood cells were separated on a CapcellPak C8 column using a mixture of methanol and 1mM ammonium formate from the C16 to C26 fatty acyl chains based on the length of total carbon chains and the nature of

Naoko Kaga; Saiko Kazuno; Hikari Taka; Kazuhisa Iwabuchi; Kimie Murayama

2005-01-01

317

Ion exchange and affinity chromatography in the scaleup of the purification of alpha-galactosidase from soybean seeds.  

PubMed

Soybeans (Glycine max) contain an alpha-galactosidase that makes up a small fraction of the total protein of the seed. The properties of this enzyme are of interest because of its potential to convert the galactooligosaccharides, stachyose and raffinose, in soybean meal to sugars digestible in the human gastro intestinal tract and thereby increase potential uses of this vegetable protein source in human and animal foods. Study of this enzyme required the isolation of milligram quantities of electrophoretically pure protein from ground soybeans and therefore, scaleup of laboratory procedures by a factor of 300 times. Large scale acid precipitation, ammonium sulfate precipitation, and centrifugal recovery of the precipitated protein allowed alpha-galactosidase to be isolated from 45.5 kg soybean meal containing 17.1 kg protein, to obtain an enzyme extract with a specific activity of 90 to 100. A novel combination of strong anion exchange and cation exchange chromatography followed by Concanavalin-A affinity chromatography with a methyl alpha-D mannoside gradient gave alpha-galactosidase with an average specific activity of 56,000. Ion exchange chromatography preceding Concanavalin-A affinity chromatography allowed elimination of a relatively costly melibiose affinity chromatography step (which followed the Concanavalin-A column In the laboratory procedure) thereby making scaleup practical. PMID:18597377

Porter, J E; Ladisch, M R; Herrmann, K M

1991-02-20

318

Quantitative determination of non-ionic surfactants by high-performance liquid-chromatography-ion trap mass-spectrometry  

Microsoft Academic Search

Summary  This work presents a method for the qualitative and quantitative analysis of non-ionic surfactant of the fatty alcohol ethoxylate\\u000a and nonylphenyl ethoxylate types in lanolin.\\u000a \\u000a The lanolin dissolved in a mixture of methanol and methyl tert-butyl ether was analyzed with no time-consuming sample preparation.\\u000a Coupling high-performance liquid-chromatography with electrospray ion trap mass-spectrometry gives an extracted ion chromatogram\\u000a of every individual

J. Ungewiß; J.-P. Vietzke; M. Strassner; C. Rapp; B. Feuerstein

2003-01-01

319

Determination of arsenic(III) and arsenic(V) in ferric chloride-hydrochloric acid leaching media by ion chromatography  

SciTech Connect

An analytical method has been developed to determine arsenic(V) in ferric chloride-hydrochloric acid leaching media using ion chromatography with conductivity detection. Oxidation of As(III) by aqua regia allows arsenic(III) to be determined by difference. The method involves a preseparation of trace quantities of arsenic from the relatively large concentrations of ferric chloride and hydrochloric acid prior to the ion chromatography measurement. Iron(III) is separated by passing through a hydrogen-form cation exchange column, and arsenic(III) and arsenic(V) are then eluted with water. The effect of the concentration of acid in this separation is discussed. The effluent collected from the cation exchange column is evaporated to remove the hydrochloric acid. The accuracy and precision of the method were determined from the analysis of various synthetic solutions and are discussed; an accuracy of +/-4% was obtained even at arsenic(V) concentrations as low as 10 ppm. The extent of oxidation of arsenic(III) in acidic ferric chloride solution and the reduction of arsenic(V) in acidic ferrous chloride solution were measured. The results obtained by ion chromatography are compared to the values realized using colorimetry after the preseparation step. 13 references, 3 figures, 4 tables.

Tan, L.K.; Dutrizac, J.E.

1985-05-01

320

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

2005-11-23

321

Improving quantitative gas chromatography-electron ionization mass spectrometry results using a modified ion source: demonstration for a pharmaceutical application.  

PubMed

Gas chromatography-mass spectrometry is a well established analytical technique. However, mass spectrometers with electron ionization sources may suffer from signal drifts, hereby negatively influencing quantitative performance. To demonstrate this phenomenon for a real application, a static headspace-gas chromatography method in combination with electron ionization-quadrupole mass spectrometry was optimized for the determination of residual dichloromethane in coronary stent coatings. Validating the method, the quantitative performance of an original stainless steel ion source was compared to that of a modified ion source. Ion source modification included the application of a gold coating on the repeller and exit plate. Several validation aspects such as limit of detection, limit of quantification, linearity and precision were evaluated using both ion sources. It was found that, as expected, the stainless steel ion source suffered from signal drift. As a consequence, non-linearity and high RSD values for repeated analyses were obtained. An additional experiment was performed to check whether an internal standard compound would lead to better results. It was found that the signal drift patterns of the analyte and internal standard were different, consequently leading to high RSD values for the response factor. With the modified ion source however, a more stable signal was observed resulting in acceptable linearity and precision. Moreover, it was also found that sensitivity improved compared to the stainless steel ion source. Finally, the optimized method with the modified ion source was applied to determine residual dichloromethane in the coating of coronary stents. The solvent was detected but found to be below the limit of quantification. PMID:21620408

D'Autry, Ward; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Van Schepdael, Ann

2011-05-14

322

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...

323

ANALYSIS FOR B-LACTAM ANTIBIOTICS IN KIDNEY TISSUE BY LIQUID CHROMATOGRAPHY WITH ELECTROSPRAY IONIZATION AND SELECTIVE REACTION MONITORING/TANDEM ION TRAP MASS SPECTROMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Eleven B-lactams antibiotics were analyzed in fortified and incurred beef kidney tissue using high-performance liquid chromatography/selective reaction monitoring/tandem ion trap mass spectrometry. The analytes included: deacetylcephapirin, amoxicillin, cephapirin, desfuroylceftiofur cysteine disul...

324

UTILIZATION OF AN EVAPORATIVE LIGHT SCATTERING DETECTOR FOR HIGH PERFORMANCE SIZE EXCLUSION CHROMATOGRAPHY OF GALACTURONIC ACID OLIGOMERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A high performance size exclusion chromatographic method utilizing an evaporative light scattering detector was developed to separate and quantify galacturonic acid (GA) oligomers. Values of k for GA monomer ranged from 0.16 in water to 0.67 in 100 mM acetic acid. In 40 mM acetic acid calibration ...

325

Model-based prediction of monoclonal antibody retention in ion-exchange chromatography.  

PubMed

In order to support a model-based process design in ion-exchange chromatography, an adsorption equilibrium model was adapted to predict the protein retention behavior from the amino acid sequence and from structural information on the resin. It is based on the computation of protein-resin interactions with a colloidal model and accounts for the contribution of each ionizable amino acid to the protein charge. As a verification of the protein charge model, the experimental titration curve of a monoclonal antibody was compared to its predicted net charge. Using this protein charge model in the computation of the protein-resin interactions, it is possible to predict the adsorption equilibrium constant (i.e. retention factor or Henry constant) with an explicit pH and salt dependence. The application of the model-based predictions for an in silico screening of the protein retention on various stationary phases or, alternatively, for the comparison of various monoclonal antibodies on a given cation-exchanger was demonstrated. Furthermore, considering the structural differences between charge variants of a monoclonal antibody, it was possible to predict their individual retention times. The selectivity between the side variants and the main isoform of the monoclonal antibody were computed. The comparison with the experimental data showed that the model was reliable with respect to the identification of the operating conditions maximizing the selectivity, i.e. the most promising conditions for a monoclonal antibody variant separation. Such predictions can be useful in reducing the experimental effort to identify the parameter space. PMID:23759301

Guélat, Bertrand; Delegrange, Lydia; Valax, Pascal; Morbidelli, Massimo

2013-04-22

326

Enhanced conductivity detection of common inorganic anions in electrostatic ion chromatography using water eluent.  

PubMed

To enhance the conductivity detection sensitivity of common anions (Na-anions) in electrostatic ion chromatography (EIC) by elution with water, a conductivity enhancement column packed with strong acid cation exchange resin in the H-form was inserted between an octadecyl silane (ODS)-silica separation column modified with zwitterionic surfactant (CHAPS: 3-{(3-cholamidopropyl)-dimethylammonio} propanesulfonate) and a conductivity detector. Specifically, the Na-anion pairing is converted to H-anion pairing after the EIC separation and then detected sensitively by the conductivity detector. The effects of conductivity enhancement and suppression in the EIC by the enhanced conductivity detection were characterized for the common strong acid anions such as SO4(2-), Cl(-), NO3(-), I(-) and ClO4(-) and weak acid anions such as F(-), NO2(-), HCOO(-), CH3COO(-) and HCO3(-). For the conductivity enhancement effect in the EIC, it is found that the conductivity of measured for all strong acid anions (Na-anions) was enhanced according to the theoretical conductivity predicted for H-anions and that of the measured for weak acid anions was suppressed depending on their pKa of H-anions. For the calibration linearity in the EIC, the strong acid anions were linear (r2 = 0.99 - 1.00) because the degree of dissociation is almost 1.0 over all the concentration range and that of the weak acid anions was non-linear because the degree of dissociation decreased by increasing the concentration of the weak acid anions. In conclusion, the EIC by enhanced conductivity detection was recognized to be useful only for the strong acid anions in terms of conductivity detection and calibration linearity. PMID:22799191

Kozaki, Daisuke; Shi, Chao-Hong; Tanaka, Kazuhiko; Nakatani, Nobutake

2012-04-01

327

Evaluation of the botanical authenticity and phytochemical profile of black cohosh products by high-performance liquid chromatography with selected ion monitoring liquid chromatography-mass spectrometry.  

PubMed

Black cohosh (Actaea racemosa L., syn. Cimicifuga racemosa L.) has become increasingly popular as a dietary supplement in the United States for the treatment of symptoms related to menopause, but the botanical authenticity of most products containing black cohosh has not been evaluated, nor is manufacturing highly regulated in the United States. In this study, 11 black cohosh products were analyzed for triterpene glycosides, phenolic constituents, and formononetin by high-performance liquid chromatography-photodiode array detection and a new selected ion monitoring liquid chromatography-mass spectrometry method. Three of the 11 products were found to contain the marker compound cimifugin and not cimiracemoside C, thereby indicating that these plants contain Asian Actaea instead of black cohosh. One product contained both black cohosh and an Asian Actaea species. For the products containing only black cohosh, there was significant product-to-product variability in the amounts of the selected triterpene glycosides and phenolic constituents, and as expected, no formononetin was detected. PMID:16637680

Jiang, Bei; Kronenberg, Fredi; Nuntanakorn, Paiboon; Qiu, Ming-Hua; Kennelly, Edward J

2006-05-01

328

Fractionation of metal complexes with dissolved organic matter in a rhizosphere soil solution of a humus-rich Andosol using size exclusion chromatography with inductively coupled plasma-mass spectrometry  

Microsoft Academic Search

To better understand the behavior of metals in soil–plant systems, their physicochemical forms in rhizosphere soil should be elucidated. The dissolved organic matter (DOM) in a soil solution influences the mobility and bioavailability of metals in soil. The present study examined the effects of plant growth on DOM–metal complexes in a rhizosphere soil solution using size exclusion chromatography combined with

Akira Takeda; Hirofumi Tsukada; Yuichi Takaku; Shun’ichi Hisamatsu

2009-01-01

329

Determination of diallyldimethylammonium chloride in drinking water by reversed-phase ion-pair chromatography-electrospray ionization mass spectrometry.  

PubMed

A method for the direct determination of diallyldimethylammonium chloride (DADMAC) in water samples, using ion-pair liquid chromatography-mass spectrometry system was developed. The chromatographic separation was performed using a C18 column. The type, the concentration of ion-pair reagent and the pH were optimized to give good chromatographic retention and sensitivity for DADMAC. Quantification was achieved in the positive electrospray ionization mode using selected ion monitoring. The cone voltage was also studied to establish the optimal experimental conditions. Finally, the reproducibility of the proposed method was shown by good run-to-run and day-to-day precision values. No sample preparation was required and the detection limit was 0.1 microg/L. The method was used to detect residual DADMAC at drinking water treatment plants in Tianjin, north China. The concentration of DADMAC observed in drinking water ranged from below quantitation limit to 22.0 microg/L. PMID:16243342

Jin, Fen; Hu, Jianying; Yang, Min; Jin, Xiaohui; He, Wenjie; Han, Hongda

2005-10-21

330

Enthalpic interactions in size exclusion chromatography of pullulan and cellulose in LiCl– N, N-dimethylacetamide  

Microsoft Academic Search

Enthalpic phenomena were shown to contribute to the size exclusion separation mechanisms during chromatographic analysis of solutions of pullulan and cellulose in LiCl–N,N-dimethylacetamide (LiCl–DMAc) solvent and eluent. The effect of LiCl concentration in the sample solutions and the effect of temperature were of the same order of magnitude for both pullulan and cellulose samples. This led to systematic errors in

Matija Strli?; Jana Kolenc; Jana Kolar; Boris Pihlar

2002-01-01

331

Preparative size-exclusion chromatography for purification and characterization of colloidal quantum dots bound by chromophore-labeled polymers and low-molecular-weight chromophores.  

PubMed

We explore the use of preparative size-exclusion chromatography (SEC) and high-performance liquid chromatography (HPLC) to purify quantum dots (QDs) after surface modification. In one example, in which Bio-Beads (S-X1) were used as the packing material for the preparative SEC column, CdSe QDs treated with a functional coumarin dye could be separated from the excess free dye by using tetrahydrofuran (THF) as the mobile phase. This column was unable to separate polymer-coated QDs from free polymer (M approximately 8000) because of the relatively low cutoff mass of the column. Here a preparative HPLC column packed with TOYOPEARL gel allowed the effective separation of polymer-bound QDs from the excess free polymer by using N-methyl-2-pyrrolidinone (NMP) as the mobile phase. When other solvents such as absolute ethanol, acetonitrile, THF, and THF-triethylamine mixtures were used as the eluent, QDs stuck to the column. While NMP was an effective medium to remove excess free polymer from the QDs, it was difficult to transfer the purified QDs to more volatile solvents and maintain colloidal stability. PMID:19446821

Wang, Mingfeng; Bardajee, Ghasem Rezanejade; Kumar, Sandeep; Nitz, Mark; Scholes, Gregory D; Winnik, Mitchell A

2009-05-03

332

Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography\\/mass spectrometry and gas chromatography\\/flame ionization detection  

Microsoft Academic Search

Fatty acid (FA) and triacylglycerol (TG) composition of natural oils and fats intake in the diet has a strong influence on the human health and chronic diseases. In this work, non-aqueous reversed-phase (NARP) and silver-ion high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection and gas chromatography with flame-ionization detection (GC\\/FID) and mass spectrometry detection are used for

Miroslav Lísa; Kate?ina Netušilová; LukᚠFran?k; Hana Dvo?áková; Vladimír Vrkoslav; Michal Hol?apek

2011-01-01

333

Validation of a Radioimmunoassay for Indole-3-Acetic Acid Using Gas Chromatography-Selected Ion Monitoring-Mass Spectrometry 1  

PubMed Central

A radioimmunoassay for indole-3-acetic acid (IAA) has been validated by comparison with a physico-chemical assay utilizing gas chromatography-selected ion monitoring-mass spectrometry and 4,5,6,7-tetradeutero-indole-3-acetic acid as an internal standard. The radioimmunoassay provided a reliable estimate of the free IAA content of etiolated corn shoots. However, base hydrolysis of extracts for determination of ester IAA released substances which interfered with the radioimmunoassay. Interference was detected by internal controls and by lack of agreement with the mass spectral method. Interfering compounds could be removed from extracts by chromatography on diethylaminoethyl- and hydroxypropylated (lipophilic) Sephadex G-25. Following such purification the radioimmunoassay estimate of the total (free + ester) IAA content of etiolated corn shoots agreed with the mass spectral method within 2% on the average.

Pengelly, William L.; Bandurski, Robert S.; Schulze, Aga

1981-01-01

334

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

335

Development and application of a universal method for quantitation of anionic constituents in active pharmaceutical ingredients during early development using suppressed conductivity ion chromatography  

Microsoft Academic Search

A universal method for quantitation of anionic substances in active pharmaceutical ingredients (API) during early development was developed using ion chromatography (IC). The method was developed to allow rapid characterization of APIs in support of early clinical studies The method parameters were chosen to allow quantitation of monovalent, divalent, and trivalent inorganic ions as well as monvalent and divalent carboxylic

Scott A Cassidy; Charles W Demarest; Paul B Wright; Jayne B Zimmerman

2004-01-01

336

SEPARATION OF UNDERIVATIZED SMALL PEPTIDES ON A POROUS GRAPHITIC CARBON COLUMN BY ION-PAIR CHROMATOGRAPHY AND EVAPORATIVE LIGHT SCATTERING DETECTION  

Microsoft Academic Search

Separations of small peptides (di-, tri- and tetrapeptides) using ion-pair chromatography and evaporative light scattering detection have been investigated with a porous graphitic carbon stationary phase, Hypercarb®. Five perfluorinated carboxylic acids (trifluoroacetic (TFA), pentafluoropropanoic (PFPA), heptafluorobutanoic (HFBA), nonafluoropentanoic (NFPA) and tridecafluoroheptanoic (TDFHA) acids) have been evaluated as ion-pairing agents. Influence of the percentage of organic modifier, concentration, and chain length

A. Ait Adoubel; S. Guenu; C. Elfakir; M. Dreux

2000-01-01

337

Profiling and quantification of isoflavones in soymilk from soy protein isolate using extracted ion chromatography and positive ion fragmentation techniques  

Microsoft Academic Search

Dietary supplements on soy based foods and beverages are increasingly gaining prominence all over the world. In this study, liquid chromatography coupled with positive electrospray ionisation tandem mass spectrometry (LC-ESI-MS) and diode array detection was used for the quantitation and characterisation of isoflavones in fermented and unfermented soymilk made from soy protein isolate SUPRO 590. Bifidobacterium animalis ssp. lactis Bb12

Daniel O. Otieno; Harry Rose; Nagendra P. Shah

2007-01-01

338

Determination of perchlorate in drinking water by ion chromatography using macrocycle-based concentration and separation methods.  

PubMed

Macrocycle-based ion chromatography provides a convenient, reliable method for the determination of perchlorate ion, which is currently of great interest to the environmental community. This study shows that effective perchlorate determinations can be made using standard conductimetric detection by combining an 18-crown-6-based mobile phase with an underivatized reversed-phase mobile phase ion chromatography (MPIC) column. One unique feature of this method is the flexibility in column capacity that is achieved through simple variations in eluent concentrations of 18-crown-6 and KOH, facilitating the separation of target analyte anions such as perchlorate. Using a standard anion exchange column as concentrator makes possible the determination of perchlorate as low as 0.2 ug/L in low ionic strength matrices. Determination of perchlorate at the sub-ug/L level in pure water and in spiked local city hard water samples with high background ion concentrations can be achieved this way. However, like other IC techniques, this method is challenged to achieve analyses at the ug/L level in the demanding high ionic strength matrix described by the United States Environmental Protection Agency (EPA) (1,000 mg/L chloride, sulfate and carbonate). We approached this challenge by use of the Cryptand C1 concentrator column, provided by Dionex Corporation, to effectively preconcentrate perchlorate while reducing background ion concentrations in the high ionic strength matrix. The retention characteristics of the concentrator column were studied in order to maximize its effectiveness for perchlorate determinations. The method makes possible the determination of perchlorate at the 5 ug/L level in the highest ionic strength matrix described by the EPA. PMID:16516902

Lamb, John D; Simpson, David; Jensen, Bryce D; Gardner, Joseph S; Peterson, Quinn P

2006-03-03

339

Determination of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry on an ion trap.  

PubMed

Test methods have to be developed by laboratories for official control to monitor possible misuse of veterinary drugs in animal productions, also through feeding stuff. A novel method for identification and quantification of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry in an ion trap (LC/ESI-MS/MS) is herein described; after a single-step cleanup by liquid-liquid extraction from the feed and separation by reversed-phase liquid chromatography, levamisole was determined and unambiguously confirmed by tandem mass spectrometry, on the basis of two product ions. The method was in-house validated, according to the Regulation 882/2004/EC, evaluating trueness, repeatability, within-laboratory reproducibility, ruggedness, specificity, and the limit of quantification (LOQ). The method is reliable and specific for complete and complementary feeds for pigs, cattle, rabbits and poultry; very good mean recoveries (higher than 92 %) and precision (RSD values?ion trap, from 50 up to 2000?m/z; the presence of levamisole was hypothesised, on the basis of the most abundant ion and its fragmentation pattern. Then, levamisole was unambiguously confirmed by the ion trap LC/ESI-MS/MS method. PMID:22368052

Gallo, Pasquale; Fabbrocino, Serena; Serpe, Luigi

2012-04-15

340

Determination of the interparticle void volume in packed beds via intraparticle Donnan exclusion.  

PubMed

Interparticle void volumes and porosities of packed capillaries have been determined using intraparticle Donnan exclusion of a small, unretained, co-ionic tracer (nitrate ions). The operational domain of this approach has been characterized for bare silica, reversed-phase, and strong cation-exchange materials (with different particle sizes and intraparticle pore sizes) in dependence of the mobile phase ionic strength. Interparticle porosities agree well with those analyzed by inverse size-exclusion chromatography (ISEC). Limitations to the use of Donnan exclusion (electrostatic exclusion) and ISEC (mechanical exclusion) arise as either type of exclusion becomes noticeable also in the cusp regions between the particles, or as the intraparticle pores are so large that complete electrostatic and size-exclusion are difficult to realize. Our data confirm that intraparticle Donnan exclusion presents a most simple, fast, and reliable approach for the analysis of packing densities. PMID:20031142

Jung, Stephanie; Ehlert, Steffen; Pattky, Martin; Tallarek, Ulrich

2009-12-05

341

Monitoring of N-nitrosodiethanolamine in cosmetic products by ion-pair complex liquid chromatography and identification with negative ion electrospray ionization mass spectrometry  

Microsoft Academic Search

A high-performance liquid chromatographic (HPLC) method was developed for the determination of N-nitrosodiethanolamine (NDELA), which is a non-volatile N-nitrosoamine. In this method, sodium 1-octanesulfonate has been used as an ion complexation agent for NDELA. The resulting complex was analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC) using a Eurospher-100 C18 column (250×4.6mm, 5?m), water\\/acetonitrile (95\\/5, v\\/v) and UV detection at 234nm.

Alireza Ghassempour; Monireh Abbaci; Zahra Talebpour; Bernhard Spengler; Andreas Römpp

2008-01-01

342

Determination of methylmercury in waters using sodium tetraphenylaborate derivatization/solvent extraction and gas chromatography-ion trap mass spectrometry  

SciTech Connect

An analytical approach involving aqueous-phase derivatization followed by gas chromatography/ion trap mass spectrometry (GC/ITMS) for the determination of methylmercury in waters is described. The aqueous-phase derivatization is based on the formation of a more hydrophobic compound between MeHg{sup +} and BPh{sub 4}{sup -}, i.e., MeHgPh, which is extractable into dichloromethane. The detection limit of the method for MeHg is 1 ng/mL for Hg when 100 ml water was analyzed. Recoveries from standard addition to tap water, lake water are 96 {+-} 8% and 92 {+-} 8%, respectively.

Guanglin Hu; Wang Xiaoru; Wang Yiru [Xiamen Univ. (China)] [and others

1997-11-01

343

Fast gas chromatography and negative-ion chemical ionization tandem mass spectrometry for forensic analysis of cannabinoids in whole blood  

Microsoft Academic Search

The present work describes a fast gas chromatography\\/negative-ion chemical ionization tandem mass spectrometric assay (Fast GC\\/NICI-MS\\/MS) for analysis of tetrahydrocannabinol (THC), 11-hydroxy-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH) in whole blood. The cannabinoids were extracted from 500?L of whole blood by a simple liquid–liquid extraction (LLE) and then derivatized by using trifluoroacetic anhydride (TFAA) and hexafluoro-2-propanol (HFIP) as fluorinated agents. Mass spectrometric

Aurélien Thomas; Christèle Widmer; Gérard Hopfgartner; Christian Staub

2007-01-01

344

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

345

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

346

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

2013-02-09

347

A Modified Metal-Ion Affinity Chromatography Procedure for the Purification of Histidine-Tagged Recombinant Proteins Expressed in Drosophila S2 Cells  

Microsoft Academic Search

We have developed a modified method of immobilized metal-ion affinity chromatography (IMAC) that can be used for the purification of histidine-tagged proteins from conditioned medium containing free copper ions. Classical methods of IMAC purification, using resins such as Ni–NTA, have proven inefficient for this type of purification and require multiple steps due to the interference of divalent copper ions with

Ruth V. Lehr; Louis C. Elefante; Kristine K. Kikly; Shawn P. O'Brien; Robert B. Kirkpatrick

2000-01-01

348

Evaluation of three ionisation modes for the analysis of chlorinated paraffins by gas chromatography/ion-trap mass spectrometry.  

PubMed

The applicability of three ionisation modes to the analysis of short-chain chlorinated paraffins (SCCPs) using gas chromatography coupled with mass spectrometry (GC/MS) was evaluated. MS conditions for electron ionisation (EI), positive chemical ionisation (PCI) and electron-capture negative ionisation (ECNI) were optimised using commercially available individual tetra-, penta- and hexachlorodecanes. In addition, mass spectra were studied and fragmentation pathways were proposed for each individual congener. Different fragment ions were evaluated for quantification, and ECNI-MS using [HCl2](-) and [Cl2](-*) ions was selected for the determination of SCCPs. Quality parameters (repeatability, limits of detection and calibration range) were established for the proposed method, which was then applied to the analysis of SCCPs in river sediments. PMID:14978797

Castells, P; Santos, F J; Galceran, M T

2004-01-01

349

Analysis of tryptamine at the femtomole level in tissue using negative ion chemical ionization gas chromatography-mass spectrometry.  

PubMed

An ultra sensitive method for the detection of tryptamine, an endogenous amine in mammalian neuronal systems, at the femtomole level has been developed using negative chemical ionization gas chromatography-mass spectrometry (NCI-GC-MS). The amine is converted into a perfluorinated spirocyclic derivative, e.g. 1-pentafluoro-2-methylenepyrrolidine-3-spiro-3'-(3H-indole) which is detected using selected-ion monitoring of the (M-2HF) ions of the endogenous and deuterated internal standard compounds. Two mass spectrometers were compared; they gave minimum detectable quantities from tissue samples of 40 pg (VG-7070F) and 0.9 pg (VG-70S) respectively. These detection levels are approximately 5-200 times lower than have been obtained by previous MS methods. PMID:3403664

Durden, D A; Boulton, A A

1988-05-25

350

Quantitative analysis of [Dmt(1)]DALDA in ovine plasma by capillary liquid chromatography-nanospray ion-trap mass spectrometry.  

PubMed

The synthetic opioid peptide analog Dmt-D-Arg-Phe-Lys-NH(2) ([Dmt(1)]DALDA; [Dmt= 2',6'-dimethyltyrosine) is a highly potent and selective mu opioid-receptor agonist. A very sensitive and robust capillary liquid chromatography/nanospray ion-trap (IT) mass spectrometry method has been developed to quantify [Dmt(1)]DALDA in ovine plasma, using deuterated [Dmt(1)]DALDA as the internal standard. The standard MS/MS spectra of d(0)- and d(5)-[Dmt(1)]DALDA were obtained, and the collision energy was experimentally optimized to 25%. The product ion [ M + 2H-NH(3)](2+) (m/z 312.2) was used to identify and to quantify the synthetic opioid peptide analog in ovine plasma samples. The MS/MS detection sensitivity for [Dmt(1)]DALDA was 625 amol. A calibration curve was constructed, and quantitative analysis was performed on a series of ovine plasma samples. PMID:15026001

Wan, Haibao; Umstot, Edward S; Szeto, Hazel H; Schiller, Peter W; Desiderio, Dominic M

2004-04-15

351

Thiacalix[4]arenetetrasulfonate as specific pre-column chelating reagent for nickel(II) ion in kinetic differentiation mode high-performance liquid chromatography  

Microsoft Academic Search

Thiacalix[4]arenetetrasulfonate (TCAS) has been examined as a pre-column chelating reagent for the determination of trace metal ions by kinetic differentiation mode (KD) ion-pair reversed-phase high-performance liquid chromatography (HPLC) with spectrophotometric detection. Among 14 kinds of common metal ions tested here, viz. Al(III), Ca(II), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Hg(II), Mg(II), Mn(II), Ni(II), Pb(II), V(V), and Zn(II) ion, only Ni(II) ion

Hiroaki Matsumiya; Takeshi Ishida; Nobuhiko Iki; Sotaro Miyano

2003-01-01

352

THE MECHANISM FOR THE EXCLUSION OF SUGARS FROM THE WATER IN A MODEL OF THE LIVING CELL: THE ION-EXCHANGE RESIN: PORE SIZE OR WATER STRUCTURE?  

Microsoft Academic Search

SUMMARY The equilibrium distribution coefficients (p-value) of D-arabinose between the water in sulfonate ion-exchange resin and the external aqueous solution vary with the nature of the five alkali metal counterions studied. The strongest exclusion (lowest p -value) is found in the Li+ resin and the least exclusion (highest p -value) in the Cs+ resin. The p-value decreases with the increasing

G. N. LING; A. M. SOBEL

353

Preparation of immunoglobulin Y from egg yolk using ammonium sulfate precipitation and ion exchange chromatography.  

PubMed

The objective of this study was to develop an economical, simple, and large-scale separation method for IgY from egg yolk. Egg yolk diluted with 9 volumes of cold water was centrifuged after adjusting the pH to 5.0. The supernatant was added with 0.01% charcoal or 0.01% carrageenan and centrifuged at 2,800 x g for 30 min. The supernatant was filtered through a Whatman no. 1 filter paper and then the filtrate was concentrated to 20% original volume using ultrafiltration. The concentrated solution was further purified using either cation exchange chromatography or ammonium sulfate precipitation. For the cation exchange chromatography method, the concentrated sample was loaded onto a column equilibrated with 20 mM citrate-phosphate buffer at pH 4.8 and eluted with 200 mM citrate-phosphate buffer at pH 6.4. For the ammonium sulfate precipitation method, the concentrated sample was twice precipitated with 40% ammonium sulfate solution at pH 9.0. The yield and purity of IgY were determined by ELISA and electrophoresis. The yield of IgY from the cation exchange chromatography method was 30 to 40%, whereas that of the ammonium sulfate precipitation was 70 to 80%. The purity of IgY from the ammonium sulfate method was higher than that of the cation exchange chromatography. The cation exchange chromatography could handle only a small amount of samples, whereas the ammonium sulfate precipitation could handle a large volume of samples. This suggests that ammonium sulfate precipitation was a more efficient and useful purification method than cation exchange chromatography for the large-scale preparation of IgY from egg yolk. PMID:17234857

Ko, K Y; Ahn, D U

2007-02-01

354

Speciation of Zn-aminopolycarboxylic complexes by electrospray ionization mass spectrometry and ion chromatography with inductively coupled plasma mass spectrometry.  

PubMed

The speciation of Zn-aminopolycarboxylic complexes was investigated using both electrospray ionization mass spectrometry (ESI-MS) and ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP-MS). The resulting ESI mass spectra indicated that [Zn(HEDTA)](1-), [Zn(NTA)](1-), [Zn(EDTA)](2-) and [Zn(DTPA)](3-) were all simultaneously detected in solution; [Zn(NTA)](1-) exhibited the weakest intensity of all these Zn-aminopolycarboxylic complexes. IC/ICP-MS was also successfully used to separate Zn complexes by anion-exchange chromatography using a mobile phase containing 30 mM (NH(4))(2)HPO(4) at pH 7.5 giving reasonable resolution within 15 min. A weak peak attributable to the poor stability [Zn(NTA)](1-) ion was also observed using IC/ICP-MS. With the exception of [Zn(NTA)](1-), detection limits ranging from 0.5 to 1.0 microg/L were obtained and the proposed method was used for the determination of Zn aminopolycarboxylic complexes in soil solution. PMID:19127531

Chen, ZuLiang; Owen, Gary; Megharaj, Mallavarapu; Naidu, Ravendra

2009-02-01

355

Quantification of polyphosphate: different sensitivities to short-chain polyphosphate using enzymatic and colorimetric methods as revealed by ion chromatography.  

PubMed

Polyphosphate is ubiquitous and has a variety of biochemical functions. Among polyphosphate quantification methods, an enzymatic assay using Escherichia coli polyphosphate kinase (PPK), in which polyphosphate is converted to adenosine 5'-triphosphate and quantified by luciferase assay, is the most specific and most sensitive. However, chain-length specificity of the assay has not been analyzed in detail so far. Ion chromatography equipped with an on-line hydroxide eluent generator enabled us to analyze polyphosphate up to 50 inorganic phosphate (P(i)) residues, and we employed this method to investigate the chain-length specificity of PPK in this study. Several fractions of short-chain polyphosphate were prepared by electrophoresis, and the chain-length distribution was analyzed before and after 1-6 h PPK reaction by ion chromatography. Polyphosphates longer than 23 P(i) residues were processed by PPK completely after 1 h incubation, but complete processing of those between 11 and 22 P(i) residues required 6h incubation. Limited processing of polyphosphates of 10 P(i) residues or shorter were observed even after 6h incubation. Metachromasy of Toluidine blue O, an alternative method for polyphosphate quantification, showed broader chain-length specificity although it was not as sensitive as the enzymatic assay. Combination of these two methods would be practically applicable to analysis of polyphosphate dynamics in living organisms. PMID:15113689

Ohtomo, Ryo; Sekiguchi, Yoko; Mimura, Tetsuro; Saito, Masanori; Ezawa, Tatsuhiro

2004-05-15

356

Liquid chromatography/tandem mass spectrometry of glycolytic intermediates: deconvolution of coeluting structural isomers based on unique product ion ratios.  

PubMed

A method has been developed for rapid quantification of nine glycolytic intermediates using ultraperformance liquid chromatography/electrospray-tandem mass spectrometry (UPLC/ESI-MS/MS) to monitor the metabolism of glucose during microbial fermentation. Because comprehensive chromatographic separation is not required, analysis time is significantly less than traditional ion exchange liquid chromatography assays or enzymatic assays. Complete glycolytic intermediate analysis by LC/MS/MS can be achieved in less than 7 min per sample. Quantification is accomplished using isotopically labeled glucose, glucose-6-phosphate, and pyruvate as internal standards. In addition, a method to deconvolute peak areas of coeluting structural isomers based on unique product ion ratios has been developed to allow accurate quantification of the individual isomers 2-phosphoglycerate and 3-phosphoglycerate, as well as glucose-6-phosphate and fructose-6-phosphate. Intrasample precisions for glycolytic intermediate measurements in cell-free extracts using this method vary between 0.9% and 11.8%, averaging 3.5% (RSD). Calibration curves are linear over the range 0.1-100 microg/mL, and detection limits are estimated at 2-49 ng/mL. Spike recoveries in cell extracts vary from 53% to 127% averaging 91%. This method has the potential to demonstrate correlation of glycolytic intermediate flux to microbial production profiles toward acceleration of the bioprocess development cycle. PMID:19354282

Ross, Keri Lyn; Dalluge, Joseph J

2009-05-15

357

This-layer chromatography\\/electrospray ionization triple-quadrupole linear ion trap mass spectrometry system: analysis of rhodamine dyes separated on reversed-phase C8 plates  

Microsoft Academic Search

The direct analysis of separated rhodamine dyes on reversed-phase C thin-layer chromatography plates using a surface sampling\\/electrospray emitter probe coupled with a triple-quadrupole linear ion trap mass spectrometer is presented. This report represents continuing work to advance the performance metrics and utility of this basic surface sampling electrospray mass spectrometry system for the analysis of thin-layer chromatography plates. Experimental results

Michael J. Ford; Vilmos Kertesz; Gary J. Van Berkel

2005-01-01

358

Characterisation of humic substances using atmospheric pressure chemical ionisation and electrospray ionisation mass spectrometry combined with size-exclusion chromatography  

Microsoft Academic Search

Humic substances were analysed by atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI) mass spectrometry in positive and negative modes. Using APCI the average m\\/z range of humic substances was reduced 5-fold compared to ESI. High-resolution time-of-flight mass spectrometry revealed the formation of multiply charged molecules in the ESI mode. Moreover, it was possible to obtain daughter ion mass

Thomas Pfeifer; Uwe Klaus; Ralf Hoffmann; Michael Spiteller

2001-01-01

359

Confirmation of clorsulon residues in cattle kidney by capillary gas chromatography-negative-ion chemical-ionization mass spectrometry.  

PubMed

A confirmatory assay for residues of the anthelmintic agent clorsulon [4-amino-6-(trichloroethenyl)-1,3-benzenedisulfonamide] in cattle kidney tissue has been developed. The assay involves isolation of a drug-containing fraction by solvent extraction, methylation of the analyte, and fused-silica capillary column gas chromatography-negative-ion chemical-ionization mass spectrometry of the pentamethyl derivative of clorsulon. The intensities of four negative ions [m/z 406 and 408 (trichloro species) and m/z 413 and 415 (dichloro species)] are monitored. Confirmation of the presence of drug in an analyte requires that all four ions appear at the appropriate retention time with their intensity ratios within 10-15% of those arising from analysis of the reference standard, methylated clorsulon; the lower limit of detection is 3 ppb. Quantification of the drug is based on the intensity of the m/z 406 ion. Identification and quantification of residues by the gas chromatographic-mass spectrometric assay gave results in good agreement with those obtained with an electron-capture gas chromatographic assay. PMID:3654857

Wehner, T A; Wood, J S; Walker, R; Downing, G V; Vandenheuvel, W J

1987-07-24

360

High-titer preparation of Bombyx mori nucleopolyhedrovirus (BmNPV) displaying recombinant protein in silkworm larvae by size exclusion chromatography and its characterization  

PubMed Central

Background Budded baculoviruses are utilized for vaccine, the production of antibody and functional analysis of transmembrane proteins. In this study, we tried to produce and purify the recombinant Bombyx mori nucleopolyhedrovirus (rBmNPV-hPRR) that displayed human (pro)renin receptor (hPRR) connected with FLAG peptide sequence on its own surface. These particles were used for further binding analysis of hPRR to human prorenin. The rBmNPV-hPRR was produced in silkworm larvae and purified from its hemolymph using size exclusion chromatography (SEC). Results A rapid method of BmNPV titer determination in hemolymph was performed using quantitative real-time PCR (Q-PCR). A correlation coefficient of BmNPV determination between end-point dilution and Q-PCR methods was found to be 0.99. rBmNPV-hPRR bacmid-injected silkworm larvae produced recombinant baculovirus of 1.31 × 108 plaque forming unit (pfu) in hemolymph, which was 2.8 × 104 times higher than transfection solution in Bm5 cells. Its purification yield by Sephacryl S-1000 SF column chromatography was 264 fold from larval hemolymph at 4 days post-injection (p.i.), but 35 or 39 fold at 4.5 or 5 days p.i., respectively. Protein patterns of rBmNPV-hPRR purified at 4 and 5 days were the same and ratio of envelope proteins (76, 45 and 35 kDa) to VP39, one of nucleocapsid proteins, increased at 5 days p.i. hPRR was detected in only purified rBmNPV-hPRR at 5 days p.i.. Conclusion The successful purification of rBmNPV-hPRR indicates that baculovirus production using silkworm larvae and its purification from hemolymph by Sephacryl S-1000 SF column chromatography can provide an economical approach in obtaining the purified BmNPV stocks with high titer for large-scale production of hPRR. Also, it can be utilized for further binding analysis and screening of inhibitors of hPRR.

Kato, Tatsuya; Manoha, Suganthi Lavender; Tanaka, Shigeyasu; Park, Enoch Y

2009-01-01

361

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

2013-07-23

362

Determination of Cs137 in environmental water by ion-exchange chromatography  

Microsoft Academic Search

Methods of Cs-137 determination employing ion-exchange concentration in environmental waters such as seawater and river water have been reviewed. Ammonium molybdophosphate (AMP) is the most used inorganic ion exchanger for the determination of cesium in water. Since AMP could be obtained only in the form of fine crystals, it was difficult to use it in the columns for separation and

Sushma Gaur

1996-01-01

363

Size exclusion and reversed-phase high-performance liquid chromatography/UV for routine control of thermal processing of cows' and donkey milk major proteins.  

PubMed

Cows' and donkey milks (raw and thermally processed) and respective whey were analysed for quantification of major proteins. Two different chromatographic approaches, size exclusion (SE-HPLC) and reversed-phase high performance liquid chromatography (RP-HPLC) both coupled to UV detection were used. Usefulness of these methods for routine control of the effect of thermal processing was evaluated. The external standard method was used to calibrate the SE-HPLC and RP-HPLC systems. Concerning quantification of ?-lactoglobulin (?-lg), ?-lactalbumin (?-la), lysozyme (lys), and total casein (cn), no significant differences between results obtained by SE-HPLC and by RP-HPLC (t-test, P>0·05) were observed for raw milks and whey. Heating of cows' milk promoted aggregation of denatured proteins as observed by SE-HPLC, whereas ?-la and ?-lg from donkey milk were stable to thermal processing at 100 °C (5 min). Lys was quantified in donkey raw milk and whey however, in thermally processed donkey milk lys was denatured and could not be quantified by HPLC. PMID:22420770

Pinho, Carina; Martins, Zita E; Petisca, Catarina; Figurska, Agata M; Pinho, Olívia; Ferreira, Isabel M P L V O

2012-03-16

364

Amylopectin aggregation as a function of starch phosphate content studied by size exclusion chromatography and on-line refractive index and light scattering.  

PubMed

Starches with a natural 65-fold span in covalently bound phosphate content were prepared from five different crops including sorghum, cassava, three potato varieties and an exotic ginger plant, Curcuma zedoaria, with extreme starch phosphate content. These starches were subjected to size exclusion chromatography with refractive index detection (SEC/RI). A simple and rapid method for starch solubilisation was used. The conditions during solubilisation (2 M NaOH) and separation (10 mM NaOH, 50 degrees C) were such as enabling > 94% recovery of the starch without detectable degradation. The aggregation properties of the starch was investigated using on line refractive index/multi angle laser light scattering (RI/MALLS) detection. Three major regions in the SEC profile were identified, consisting of large amylopectin aggregates, amylopectin particles with radius of gyration (Rg) of approx 200 nm (400 nm blocklets) and amylose. A procedure for correction of light scattering signals spread over the SEC profile as a result of aggregate tailing was developed. The significance of the relative amounts of these three molecular species on standard starch pasting parameters, as measured by a Rapid Visco Analyzer (RVA), was investigated. Starches with a high amount of amylopectin aggregates showed high peak viscosities. Moreover, very high amounts of starch bound phosphate or amylose appears to suppress the content of large aggregates resulting in low viscosity. PMID:11325429

Blennow, A; Mette Bay-Smidt, A; Bauer, R

2001-06-12

365

Study of pH effects on the evolution of properties of brown-water natural organic matter as revealed by size-exclusion chromatography during photocatalytic degradation.  

PubMed

This study shows the effect of pH on the photocatalytic degradation of natural organic matter (NOM). The experiments were carried out in batch reactor (a solar UV-light simulator) with Degussa P-25 titanium dioxide (TiO2). The NOM degradation was followed by size-exclusion chromatography for dissolved organic carbon (DOC), ultraviolet absorption and fluorescence-detection (SEC-DOC, SEC-UV254 and SEC-Fl254/450). Changes in pH values affected the adsorption of NOM onto TiO2, but did not affect the photodegradation sequence of NOM. For high or low pH values, the degradation of the NOM preferentially removed the larger molecular size fraction in comparison to the middle and small molecular size fractions, resulting in the relative increase of these smaller fractions. This sequence of NOM degradation leads to the evolution of the formation potential for disinfection by-products (DBPs). Specifically, the trihalomethanes and halogenated organic compounds formation potential (THMF and AOXFP) decreased steadily. PMID:22209274

Valencia, Sergio; Marín, Juan; Velásquez, Jorge; Restrepo, Gloria; Frimmel, Fritz H

2011-12-20

366

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 30min 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 240min 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

2013-06-28

367

Nondenaturing size-exclusion chromatography-mass spectrometry to measure stress-induced aggregation in a complex mixture of monoclonal antibodies.  

PubMed

During therapeutic candidate selection, diverse panels of monoclonal antibodies (mAbs) are routinely subjected to various stress conditions, and assayed for biophysical and biochemical stability. A novel high throughput method has been developed to differentiate candidate molecules in a mixture based on their propensity for forming aggregates when subjected to agitation (vortexing) stress. Protein monomers are separated from soluble and insoluble aggregates using size exclusion chromatography, under nondenaturing conditions, and the individual components in the mixture are identified by mass spectrometry and quantitated relative to an unstressed control. An internal standard was added to the mixture after stress, and used to correct for differences in ionization between samples. Treatment of the samples with the enzyme IdeS (FabRICATOR) significantly reduces sample complexity, and allows for a large number of candidate molecules to be assessed in a single analysis. Simple and robust, the method is well suited for measuring relative aggregation propensity (RAP) in conjunction with molecule selection and coformulation development. PMID:23742703

Woodard, Jonathan; Lau, Hollis; Latypov, Ramil F

2013-06-20

368

The use of a new mobile phase, with no multivalent cation binding properties, to differentiate extracellular polymeric substances (EPS), by size exclusion chromatography (SEC), from biomass used for wastewater treatment  

Microsoft Academic Search

The fingerprints of extracellular polymeric substances (EPS) extracted from different types of biomass used for wastewater treatment (i.e., activated sludge, filamentous activated sludge, anaerobic granular sludge, anaerobic flocculated sludge) were studied by size exclusion chromatography (SEC) with Amersham Biosciences Superdex 200 10\\/300 GL column with a theoretical resolving range of 10–600kDa. A new mobile phase, which does not display binding

Maud Villain; Stéphane Simon; Isabelle Bourven; Gilles Guibaud

2010-01-01

369

Water-soluble copolymers. I. Synthesis of model dextran-g-polyacrylamides by Fe(II)\\/HâOâ initiation and characterization by aqueous size exclusion chromatography. [For use as viscosity modifiers for enhanced oil recovery  

Microsoft Academic Search

Model graft copolymers were synthesized by grafting acrylamide onto dextram (anti M\\/sub w\\/ = 500,000) utilizing the Fe(II)\\/HâOâ initiation system. Aqueous size exclusion chromatography (SEC) was used to determine the effects of changing reaction parameters on hydrodynamic dimensions of the resulting graft copolymers. It was also possible to optimize reaction conditions yielding the highest viscosity graft copolymer with the least

C. L. McCormick; L. S. Park

1981-01-01

370

Determination of traces of vanadium in molybdenum metal and compounds by ion exchange chromatography-spectrophotometry  

Microsoft Academic Search

Down to sub-parts-per-million concentrations of vanadium have been determined in up to 5 g of molybdenum metal or 10 g of its compounds. The vanadium has been separated by cation exchange chromatography in citric acid on 3-g AG50number-X8 resin columns, followed by spectrophotometry of the 4-(2-pyridylazo)resorcinol (PAR) complex in the presence of CDTA (cyclohexanediaminetetraacetic acid) to complex possible interfering trace

F. W. E. Strelow; F. W. E

1987-01-01

371

Determination of borate in extracts of gypsiferous soils by single column ion chromatography  

Microsoft Academic Search

A high performance liquid chromatography apparatus with a resin based anion exchange column and a conductivity detector were used to develop a method for borate separation and quantification in extracts of gypsiferous soils. An eluant containing 5 mMNaOH and 0.5 mMNa?benzoate was found to produce satisfactory chromato?grams. Calibration curves were linear in the range l to 7 mg B\\/L. The

L. M. Dudley

1989-01-01

372

Speciation of heavy metals in environmental water by ion chromatography coupled to ICP-MS  

Microsoft Academic Search

Biogenic (e.g. phytochelatins, porphyrins, DOM) as well as anthropogenic (e.g. NTA, EDTA, phosphonates) chelators affect the mobility and cycling of heavy metals in environmental waters. Since such chelators can form strongly bound anionic heavy metal complexes that are stable and highly mobile, anion-exchange chromatography coupled to ICP-MS was investigated. A narrow bore HPLC system was connected to a micro concentric

Adrian A. Ammann

2003-01-01

373

Generic detection of basic taxoids in wood of European Yew (Taxus baccata) by liquid chromatography-ion trap mass spectrometry.  

PubMed

The occurrence of the cardiotoxin taxine (comprising taxine B and several other basic taxoids) in leaves of Taxus baccata L. (European yew) is well known and has led to public concerns about the safety of eating or drinking from utensils crafted from the wood of this poisonous species. The occurrence of basic taxoids in the heartwood of T. baccata had not been examined in detail, although the bark is known to contain 2'?-deacetoxyaustrospicatine. Initial examination of heartwood extracts for 2'?-deacetoxyaustrospicatine by liquid chromatography-mass spectrometry (LC-MS) revealed the presence of this basic taxoid at about 0.0007% dry weight, using a standard isolated from bark. Analyses for taxine B, however, proved negative at the extract concentration analysed. Observing other basic taxoids within the heartwood extracts was facilitated by developing generic LC-MS methods that utilised a fragment arising from the N-containing acyl group of basic taxoids as a reporter ion. Of the various MS strategies available on a hybrid ion trap-orbitrap instrument that allowed observation of this reporter ion, combining all-ion collisions with high resolution ion filtering by the orbitrap was most effective, both in terms of the number of basic taxoids detected and sensitivity. Numerous basic taxoids, in addition to 2'?-deacetoxyaustrospicatine, were revealed by this method in heartwood extracts of T. baccata. Red wine readily extracted the basic taxoids from heartwood while coffee extracted them less efficiently. Contamination with basic taxoids could also be detected in soft cheese that had been spread onto wood. The generic LC-MS method for detecting basic taxoids complements specific methods for detecting taxine B when investigating yew poisoning cases in which the analysis of complex extracts may be required or taxine B has not been detected. PMID:23314400

Kite, Geoffrey C; Rowe, Emily R; Veitch, Nigel C; Turner, Jill E; Dauncey, Elizabeth A

2012-12-27

374

Formation of phosphopeptide-metal ion complexes in liquid chromatography/electrospray mass spectrometry and their influence on phosphopeptide detection.  

PubMed

Despite major advances in mass spectrometry, the detection of phosphopeptides by liquid chromatography with electrospray mass spectrometry (LC/ES-MS) still remains very challenging in proteomics analysis. Phosphopeptides do not protonate efficiently due to the presence of one or more acidic phosphate groups, making their detection difficult. However, other mechanisms also contribute to the difficulties in phosphopeptide analysis by LC/ES-MS. We report here on one such undocumented problem: the formation of phosphopeptide-metal ion complexes during LC/ES-MS. It is demonstrated that both synthetic phosphopeptides and phosphopeptides from bovine beta-casein and alpha-casein form phosphopeptide-metal ion complexes containing iron and aluminum ions, resulting in a dramatic decrease in signal intensity of the protonated phosphopeptides. The interaction of phosphopeptides with metal ions on the surface of the C18 stationary phase is also shown to alter their chromatographic behavior on reversed-phase columns such that the phosphopeptides, especially multiply phosphorylated peptides, become strongly retained and very difficult to elute. The sources of iron and aluminum are from the solvents, stainless steel, glassware and C18 material. It was also found that, upon addition of EDTA, the formation of the phosphopeptide-metal ion complex is diminished, and the phosphopeptides that did not elute from the LC column can now be detected efficiently as protonated molecules. The sensitivity of detection was greatly increased such that a tetra-phosphorylated peptide, RELEELNVPGEIVEpSLpSpSpSEESITR from the tryptic digestion of bovine beta-casein, was detected at a limit of detection of 25 fmol, which is 400 times lower than without EDTA. PMID:16136520

Liu, Suya; Zhang, Cunjie; Campbell, J Larry; Zhang, Haixia; Yeung, Ken K-C; Han, Victor K M; Lajoie, Gilles A

2005-01-01

375

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

2012-06-28

376

Analysis of perfluorooctanesulfonate and related fluorochemicals in water and biological tissue samples by liquid chromatography-ion trap mass spectrometry.  

PubMed

A method for the determination of perfluorinated compounds (PFCs) in various water and biological tissue samples was developed and validated. The contents of selected PFCs (i.e., perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorodecanoate (PFDA)) in water samples were extracted by the C(18) solid-phase extraction (SPE). The biological tissue samples (frozen-dried fish and oysters) were simply extracted by liquid-solid extraction with MTBE and adding tetrabutylammonium hydrogensulfate (TBA) as an ion-pairing reagent. The analytes were then identified and quantitated by liquid chromatography-ion trap negative electrospray mass spectrometry (LC-ESI ion-trap-MS). Limits of quantitation (LOQ) were established between 0.5 and 6 ng/l in 250 ml of water sample, while 5-50 ng/g (dry weight) for biological tissue sample. Intrabatch and interbatch precision with their accuracy at two concentration levels were also investigated. Precision for these three PFCs, as indicated by RSD, proved to be less than 11 and 17%, respectively. The total contents of PFOA, PFOS and PFDA were detected in concentrations of up to 400 ng/l in various water samples, while up to 1,100 ng/g in fish and oyster samples. PFOA and PFDA was the major PFCs detected in water samples and biological tissue samples, respectively. PMID:16439257

Tseng, Chiao-Li; Liu, Li-Lian; Chen, Chien-Min; Ding, Wang-Hsien

2005-08-15

377

Profiling of lipid species by normal-phase liquid chromatography, nanoelectrospray ionization, and ion trap-orbitrap mass spectrometry.  

PubMed

Detailed analysis of lipid species can be challenging due to their structural diversity and wide concentration range in cells, tissues, and biofluids. To address these analytical challenges, we devised a reproducible, sensitive, and integrated lipidomics workflow based on normal-phase liquid chromatography-Fourier transform mass spectrometry (LC-FTMS) and LC-ITMS(2) (ion trap tandem mass spectrometry) for profiling and structural analysis of lipid species. The workflow uses a normal-phase LC system for efficient separation of apolar and polar lipid species combined with sensitive and specific analysis powered by a chip-based nanoelectrospray ion source and a hybrid ion trap-orbitrap mass spectrometer. The workflow was executed using a primary LC-FTMS survey routine for identification and profiling of lipid species based on high-mass accuracy and retention time followed by a targeted LC-ITMS(2) routine for characterizing the fatty acid moieties of identified lipid species. We benchmarked the performance of the workflow by characterizing the chromatographic properties of the LC-MS system for general lipid analysis. In addition, we demonstrate the efficacy of the workflow by reporting a study of low-abundant triacylglycerol and ceramide species in mouse brain cerebellum and 3T3-L1 adipocytes, respectively. The workflow described here is generic and can be extended for detailed lipid analysis of sample matrices having a wide range of lipid compositions. PMID:23994565

Sokol, Elena; Almeida, Reinaldo; Hannibal-Bach, Hans Kristian; Kotowska, Dorota; Vogt, Johannes; Baumgart, Jan; Kristiansen, Karsten; Nitsch, Robert; Knudsen, Jens; Ejsing, Christer S

2013-08-29

378

Aminophosphonate-Functionalized Silica: A Versatile Chromatographic Stationary Phase for High-Performance Chelation Ion Chromatography  

Microsoft Academic Search

The chromatographic behavior of alkaline earth metals, Cu(II), Mn(II), Co(II), Zn(II), Ni(II), Pb(II), and Cd(II) on a chelating aminomethylphosphonic acid-functionalized silica column was studied in eluants with high ionic strength to suppress ion exchange. Unusual variations were found in plots of capacity factor against pH demonstrating changes in retention order, suggesting a change in the coordination of metal ions from

P. N. Nesterenko; M. J. Shaw; S. J. Hill; P. Jones

1999-01-01

379

Comparison of high resolution gas chromatography with electron impact and negative ion mass spectrometry detection for the determination of coplanar polychlorobiphenyl congeners in sewage sludges  

Microsoft Academic Search

The three most toxic coplanar PCB 77, 126 and 169 have been identified and quantified at ultra trace levels (0.02–4.8 ng\\/gdw) in swiss sewage sludge samples applying high resolution capillary gas chromatography (HRGC) and electron impact (EI) as well as negative ion chemical ionization (NCI) mass spectrometry (MS). NCI mass spectra have been dominated by the molecular ion as base

V. Raverdino; R. Holzer; J. D. Berset

1996-01-01

380

Determination of Hydroxy2-ethylenediaminetriacetic Acid (HEEDTA) and Fe-HEEDTA in Nutrient Solutions by Ion-Pair Reversed-Phase High-Performance Liquid Chromatography  

Microsoft Academic Search

A reversed-phase ion-pair liquid chromatography method for the accurate detection and determination of hydroxy-2-ethylenediaminetriacetic acid (HEEDTA) and Fe-HEEDTA has been developed. Three mobile phases containing 0.05 M tetrabutylammonium hydroxide, 0.05 M tetrabutylammonium bromide, or 0.05 M tetrabutylammonium bromide + phosphate buffer were employed in this method. Iron was added to each mobile phase after addition of the selected ion pair

Ray F. Wilson; Alaa Kamel; Mohamed Adnane; Xiotang Yu

1998-01-01

381

Analytical method development for the determination of synthetic pyrethroid insecticides in soil by gas chromatography-mass spectrometry operated in negative-ion chemical-ionization mode  

Microsoft Academic Search

An effective analytical method for the simultaneous determination of five synthetic pyrethroid insecticides in soil is developed and method performance data presented. The pyrethroid residues were extracted with hexane-dichloromethane in an ultrasonic bath. The extract was cleaned up on a Florisil column prior to determination by gas chromatography—negative-ion chemical ionization mass spectrometry (GC-NICI-MS) in selected-ion monitoring (SIM) mode. The highest

M. Yasin; P. J. Baugh; G. A. Bonwick; D. H. Davies; P. Hancock; M. Leinoudi

1996-01-01

382

Quantification of elastin cross-linking amino acids, desmosine and isodesmosine, in hydrolysates of rat lung by ion-pair liquid chromatography–mass spectrometry  

Microsoft Academic Search

The elastin cross-linking amino acids, desmosine (DES) and isodesmosine (IDE), in hydrolysates of rat lungs were quantified by ion-pair liquid chromatography–electrospray mass spectrometry. The column was a 2.0mm i.d.×150mm Develosil UG3 (ODS) with a mobile phase A of 7mM pentafluoropropionic anhydride (PFPA) using ultrapure water as the ion-pair reagent, and a mobile phase B of 7mM PFPA in 80% methanol.

Naoko Kaga; Sanae Soma; Tsutomu Fujimura; Kuniaki Seyama; Yoshinosuke Fukuchi; Kimie Murayama

2003-01-01

383

Effect of anionic ion-pairing reagent concentration (1–60 mM) on reversed-phase liquid chromatography elution behaviour of peptides  

Microsoft Academic Search

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

M. Shibue; C. T. Mant; R. S. Hodges

2005-01-01

384

Simultaneous determination of amodiaquine and its active metabolite in human blood by ion-pair liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

A sensitive and selective ion-pair liquid chromatography–tandem mass spectrometric method (IP-LC–MS\\/MS) for the simultaneous determination of amodiaquine (AQ) and its active metabolite, N-desethylamodiaquine (AQm), in human blood has been developed and validated. Pentafluoropropionic acid (PFPA) was applied as ion-pairing reagent in reversed-phase chromatographic separation. The effects of PFPA concentrations and the volume fraction of acetonitrile in the mobile phase on

Xiaoyan Chen; Pan Deng; Xiaojian Dai; Dafang Zhong

2007-01-01

385

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

386

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

2011-03-23

387

High-resolution separation of homogeneous chitooligomers series from 2-mers to 7-mers by ion-exchange chromatography.  

PubMed

Highly purified chitooligomers with single degree of polymerization are of significance for studying bioactivity of chitooligomers. However, there are few reports on high-resolution preparative separation of chitooligomers, especially for those oligomers with degree of polymerization higher than 4. This study developed a high-resolution chromatography for the preparative separation of a pure fully deacetylated chitooligomer series. A glucosamine oligomer mixture with low degree of polymerization was prepared by acid hydrolysis of a highly deacetylated chitosan. Then, six fractions were separated from the prepared oligomer mixture by ion-exchange chromatography and analyzed by HPLC and ESI/MS, which primarily contained glucosamine dimers, trimers, tetramers, pentamers, hexamers, and heptamers, respectively, with chromatographic purities over 98% for dimers to hexamers and a purity of 93% for heptamers. The yields of a single round of separation were 75, 60, 60, 55, 35, and 20 mg for glucosamine dimers, trimers, tetramers, pentamers, hexamers, and heptamers, respectively. Furthermore, a chromatographic separation model for GlcN homomers was established. The capacity factor (k) of glucosamine oligomers and their degrees of polymerization (DPs) exhibited a good correlation, lnk = 0.786 + 0.846 lnDP, (R(2) = 0.997). Based on this equation, glucosamine octamers are expected to be separated by this system. PMID:23457118

Li, Kecheng; Liu, Song; Xing, Ronge; Yu, Huahua; Qin, Yukun; Li, Rongfeng; Li, Pengcheng

2013-03-04

388

Determination of methylamines and trimethylamine-N-oxide in particulate matter by non-suppressed ion chromatography.  

PubMed

An ion chromatography method with non-suppressed conductivity detection was developed for the simultaneous determination of methylamines (methylamine, dimethylamine, trimethylamine) and trimethylamine-N-oxide in particulate matter air samples. The analytes were well separated by means of cation-exchange chromatography using a 3 mM nitric acid/3.5% acetonitrile (v/v) eluent solution and a Metrosep C 2 250 (250 mm x 4 mm i.d.) separation column. The effects of the different chromatographic parameters on the separation were also investigated. Detection limits of methylamine, dimethylamine, trimethylamine, and trimethylamine-N-oxide were 43, 46, 76 and 72 microg/L, respectively. The relative standard deviations of the retention times were between 0.42% and 1.14% while the recoveries were between 78.8% and 88.3%. The method is suitable for determining if methylamines and trimethylamine-N-oxide are a significant component of organic nitrogen aerosol in areas with high concentration of these species. PMID:20181351

Erupe, Mark E; Liberman-Martin, Allegra; Silva, Philip J; Malloy, Quentin G J; Yonis, Naomi; Cocker, David R; Purvis-Roberts, Kathleen L

2010-01-29

389

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, Zaneta; Namie?nik, Jacek

2013-05-16

390

Characterization of column packing materials in high-performance liquid chromatography by charge-detection quadrupole ion trap mass spectrometry.  

PubMed

This article reports an application of charge-detection quadrupole ion trap mass spectrometry (CD-ITMS) to characterize the column packing materials in high-performance liquid chromatography (HPLC). Both the mean mass and the mass distribution of the packing materials are obtained and used to calculate the specific surface area of unbonded silica, the carbon load of the bonded silica, and their particle size distributions. The obtained specific surface areas and carbon loads are consistent with those measured independently by nitrogen sorption and elemental analysis respectively, whereas the derived size distributions show better resolution than that measured by a laser particle size analyzer. Furthermore, we evaluate the uniformity of particle size, which is the key parameter for column efficiency of the liquid chromatography by analyzing the mass distribution of the packing materials at the top and bottom of the column. A broader mass distribution, which yields decreased column efficiency, is observed for the column top because of the excessive use of the column. Our results suggest that CD-ITMS can serve as an alternative means for the characterization of the packing materials in HPLC and is potentially useful for column quality control. PMID:21612293

Xiong, Caiqiao; Zhou, Xiaoyu; Chen, Rui; Zhang, Yiming; Peng, Wen-Ping; Nie, Zongxiu; Chang, Huan-Cheng; Liu, Huwei; Chen, Yi

2011-06-14

391

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.

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

2011-01-01

392

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

393

Strong ion-exchange centrifugal partition chromatography as an efficient method for the large-scale purification of glucosinolates.  

PubMed

The glucosinolates sinalbin and glucoraphanin were purified by strong ion-exchange displacement centrifugal partition chromatography (SIXCPC). The optimized conditions involved the biphasic solvent system ethyl acetate/n-butanol/water (3:2:5, v/v), the lipophilic anion-exchanger Aliquat 336 (trioctylmethylammonium chloride, 160 and 408 mM) and a sodium iodide solution (80 and 272 mM) as displacer. Amounts as high as 2.4 g of sinalbin and 2.6g of glucoraphanin were obtained in one step in 2.5 and 3.5h respectively, starting from 12 and 25 g of mustard and broccoli seed aqueous extracts, using a laboratory scale CPC column (200 mL inner volume). PMID:17904564

Toribio, Alix; Nuzillard, Jean-Marc; Renault, Jean-Hugues

2007-09-11

394

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

2013-08-28

395

An ion-pair high-performance liquid chromatography method for stability studies of epinephrine acid tartrate in injectable solution.  

PubMed

An isocratic technique was developed for the analysis of epinephrine acid tartrate using ion-pair high-performance liquid chromatography (HPLC) with UV detection and a phenyl reversed phase column. The chromatographic separation was accomplished by a mixture mobile phase consisting of methanol: water (50:50, v/v) containing 7.28 mM sodium dodecyl sulfate adjusted to pH 3.5. The stability of the drug in injectable solution was studied. Using the kinetic information generated from the high temperature studies at 70, 80 and 90 degrees C, an Arrhenius plot for epinephrine acid tartrate degradation was constructed and the shelf life of the drug was estimated. We concluded that the shelf life of epinephrine acid tartrate at room temperature (25 degrees C) was 346.1 days. PMID:11417386

Zarghi, A; Amini, M; Alesahebfosul, S

396

[Rapid determination of alkaloids in tobacco using gas chromatography-mass spectrometry with full scan-selected ion monitoring mode].  

PubMed

Simultaneous full scan-selected ion monitoring mode (Scan-SIM) is a new improvement method of data acquisition of gas chromatography-mass spectrometry (GC-MS). A method of determing alkaloids in tobacco was established by GC-MS with Scan-SIM. Nicotine, nornicotine, anabasine and anatabine were determined with scan mode, and myosmine, nicotyrine, 2,3'-bipyridyl and cotinine were determined with SIM mode. The average recoveries of alkaloids ranged from 94.8% to 98.8%, and the relative standard deviations were less than 6.0% (n = 5). Therefore, it is a simple, rapid, accurate method. Tobacco samples picked in different years were determined using this method, and the results were satisfactory. PMID:18724666

Wang, Baoxing; Yang, Shihua; Hou, Ying; Zeng, Xiaoying; Wu, Yi; Xu, Guowang

2008-05-01

397

Comparison of liquid chromatography using triple quadrupole and quadrupole ion trap mass analyzers to determine pesticide residues in oranges.  

PubMed

Liquid chromatography-triple quadrupole/mass spectrometry (LC-TQ/MS) and liquid chromatography-quadrupole ion trap/mass spectrometry (LC-QIT/MS) for determining bupirimate, hexaflumuron, tebufenpyrad, buprofezin, pyriproxyfen, and fluvalinate in fruits have been compared. The differences in the mass spectra obtained by triple and ion trap quadrupoles are discussed, showing how both of them provide interesting features. The evaluation of the two instruments was carried out by ethyl acetate extraction of oranges spiked with the studied pesticides at LOQ and 10 times the LOQ. Results obtained by LC-TQ/MS correlated well with those obtained by LC-QIT/MS. Recoveries were 70-94% by LC-TQ/MS and 72-92% by LC-QIT/MS with the R.S.D. from five replicate analysis 4-14% and 8-18%, respectively. Matrix effects were tested for both techniques by standard addition to blank extracts. Although the matrix effects are not originated in mass analyzer but in the LC/MS interface, they were, generally, more marked by LC-QIT-MS than by LC-TQ/MS. The limits of quantification (LOQs) were 0.005-0.2 mg kg(-1) by both equipments--appropriate values for determining these pesticides in orange from the regulatory point of view. The results indicate that the TQ provides higher precision, better linearity, it is more robust, and when the purpose of the analysis is quantitative determination, preferable over the QIT. However, the application of both mass spectrometers to analyze orange samples conventionally treated showed that any can be used for qualitative and quantitative purposes. PMID:15844516

Soler, Carla; Mañes, Jordi; Picó, Yolanda

2005-03-01

398

Chiral amino acid analysis of vinegars using gas chromatography – selected ion monitoring mass spectrometry  

Microsoft Academic Search

Twenty-five vinegars were examined quantitatively for their content of free amino acid (AA) enantiomers using chiral gas\\u000a chromatography\\/mass spectrometry. Vinegars manufactured from grape must contained l-proline (l-Pro) as the major AA. Balsamic vinegars (aceto balsamico di Modena), with one exception, contained the highest amounts of\\u000a l-AAs (861–2000?mg l–1) as well as d-AAs (46–361?mg l–1). The amounts of d-Pro and d-alanine

T. Erbe; H. Brückner

1998-01-01

399

Immobilized metal-ion affinity chromatography: imidazole proton pump and chromatographic sequelae. II. Chromatographic sequelae.  

PubMed

Isocratic elution with imidazole of some protein models from a chelating gel, CSFF-IDA-M(II), resulted in their desorption owing to the low pH(6-->4) of the mobile, phase rather than to the imidazole itself (imidazole-generated fall in pH; proton pump). Gradient elution with imidazole was best accomplished when the chelating gel was initially converted into its imidazole complex, CSFF-IDA-M(II)Im. The exploitation of the imidazole-generated proton pump in the IMAC of proteins may enhance the versatility of this type of chromatography. PMID:9174930

Sulkowski, E

400

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

2013-09-12

401

Aqueous size exclusion chromatography in semimicro and micro-columns by newly synthesized monodisperse macroporous hydrophilic beads as a stationary phase.  

PubMed

A new class of monodisperse macroporous beads in the hydrophilic form were synthesized by seeded microsuspension copolymerization of two acrylic crosslinking agents, glycerol dimethacrylate (GDMA) and glycerol-1,3-diglycerolate diacrylate (GDGDA). The monodisperse porous poly(glycerol dimethacrylate-co-glycerol-1,3-diglycerolate diacrylate), poly(GDMA-co-GDGDA) beads were highly hydrophilic in nature due to hydroxyl functionality resulting from both crosslinking agents. The beads with different particle sizes between 4.5 and 6.7 ?m and with different porous properties were obtained by changing the seed latex to monomer ratio. The bead size decreased, the average pore size increased and the specific surface area decreased with increasing seed latex to monomer ratio. Poly(GDMA-co-GDGDA) beads were slurry packed in microbore and semimicro-HPLC columns and successfully used as a stationary phase in aqueous size exclusion chromatography (SEC) mode in a micro-liquid chromatography system. The aqueous SEC runs were performed by using dextran standards in the molecular weight range of 1000-670,000 Da. SEC calibration curves exhibiting linearity in a wider range of molecular weight were obtained with the semi-micro and micro-HPLC columns packed with the poly(GDMA-co-GDGDA) beads synthesized with the seed latex to monomer ratios of 0.038 and 0.058 g/mL. The dextran standards could be eluted in an analysis time shorter than 2 min using micro or semi-micro columns packed with poly(GDMA-co-GDGDA) beads as stationary medium. These packings are suitable for molecular weight determination between 5×10(3) and 5×10(5) Da in the aqueous medium by using mobile phase flow rates in the range of 25-250 ?L/min. The average molecular weight determinations of different water soluble polymers, an ionic polymer, poly(2-dimethylaminoethyl methacrylate), a zwitterionic polymer, poly([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide), and a non-ionic polymer, poly(vinyl alcohol) were performed on a semimicro-column packed with the poly(GDMA-co-GDGDA) beads. Satisfactory results were obtained in the molecular weight determination of hydrophilic polymers by aqueous SEC. PMID:22218328

Gölgelio?lu, Ci?dem; Bayraktar, Asl?han; Celebi, Bekir; U?uzdo?an, Erdal; Tuncel, Ali

2011-12-19

402

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

2013-06-29

403

Effect of anionic ion-pairing reagent hydrophobicity on selectivity of peptide separations by reversed-phase liquid chromatography  

PubMed Central

Despite the continuing dominance of trifluoroacetic acid (TFA) as the anionic ion-pairing reagent of choice for peptide separations by reversed-phase high-performance liquid chromatography (RP-HPLC), we believe that a step-by-step approach to re-examining the relative efficacy of TFA compared to other ion-pairing reagents is worthwhile, particularly for the design of separation protocols for complex peptide mixtures, e.g., in proteomics applications. Thus, we applied RP-HPLC in the presence of different concentrations of anionic ion-pairing reagents – phosphoric acid, TFA, pentafluoropropionic acid (PFPA) and heptafluorobutyric acid (HFBA) – to a mixture of three groups of four 10-residue peptides, these groups containing peptides of +1, +3 or +5 net charge. Overall separation of the 12-peptide mixture improved with increasing reagent hydrophobicity (phosphate? < TFA? < PFPA? < HFBA?) and/or concentration of the anion, with reagent hydrophobicity having a considerably more pronounced effect than reagent concentration. HFBA, in particular, achieved an excellent separation at a concentration of just 10 mM, whereby the peptides were separated by charged groups (+1 < +3 < +5) and hydrophobicity within these groups. There was an essentially equal effect of reagent hydrophobicity and concentration on each positive charge of the peptides, a useful observation for prediction of the effect of varying counterion concentration hydrophobicity and/or concentration during optimization of peptide purification protocols. Peak widths were greater for the more highly charged peptides, although these could be decreased significantly by raising the acid concentration; concomitantly, peptide resolution increased with increasing concentration of ion-pairing reagent.

Shibue, M.; Mant, C.T.; Hodges, R.S.

2009-01-01

404

Effect of anionic ion-pairing reagent hydrophobicity on selectivity of peptide separations by reversed-phase liquid chromatography.  

PubMed

Despite the continuing dominance of trifluoroacetic acid (TFA) as the anionic ion-pairing reagent of choice for peptide separations by reversed-phase high-performance liquid chromatography (RP-HPLC), we believe that a step-by-step approach to re-examining the relative efficacy of TFA compared to other ion-pairing reagents is worthwhile, particularly for the design of separation protocols for complex peptide mixtures, e.g., in proteomics applications. Thus, we applied RP-HPLC in the presence of different concentrations of anionic ion-pairing reagents - phosphoric acid, TFA, pentafluoropropionic acid (PFPA) and heptafluorobutyric acid (HFBA)--to a mixture of three groups of four 10-residue peptides, these groups containing peptides of +1, +3 or +5 net charge. Overall separation of the 12-peptide mixture improved with increasing reagent hydrophobicity (phosphate- < TFA- < PFPA- < HFBA-) and/or concentration of the anion, with reagent hydrophobicity having a considerably more pronounced effect than reagent concentration. HFBA, in particular, achieved an excellent separation at a concentration of just 10 mM, whereby the peptides were separated by charged groups (+1 < +3 < +5) and hydrophobicity within these groups. There was an essentially equal effect of reagent hydrophobicity and concentration on each positive charge of the peptides, a useful observation for prediction of the effect of varying counterion concentration hydrophobicity and/or concentration during optimization of peptide purification protocols. Peak widths were greater for the more highly charged peptides, although these could be decreased significantly by raising the acid concentration; concomitantly, peptide resolution increased with increasing concentration of ion-pairing reagent. PMID:16013616

Shibue, M; Mant, C T; Hodges, R S

2005-07-01

405

A Computer-Based Undergraduate Exercise Using Internet-Accessible Simulation Software for the Study of Retention Behavior and Optimization of Separation Conditions in Ion Chromatography  

ERIC Educational Resources Information Center

|The ability to scan retention data over a wide range of eluent composition opens up the possibility of a computerized selection of the optimal separation conditions. The major characteristics of retention behavior, peak-shape effects and pH effects evident in ion chromatography (IC) using common stationary phases and eluents are illustrated.|

Haddad, Paul R.; Shaw, Matthew J.; Madden, John E.; Dicinoski, Greg W.

2004-01-01

406

POLAR ORGANIC CHEMICAL INTEGRATIVE SAMPLING AND LIQUID CHROMATOGRAPHY-ELECTROSPRAY/ION-TRAP MASS SPECTROMETRY FOR ASSESSING SELECTED PRESCRIPTION AND ILLICIT DRUGS IN TREATED SEWAGE EFFLUENTS  

EPA Science Inventory

The purpose of the research presented in this paper is two-fold: (1) to demonstrate the 4 coupling of two state-of-the-art techniques: a time-weighted polar organic integrative sampler (POCIS) and micro-liquid chromatography-electrospray/ion trap mass spectrometry (u-LC-6 ES/ITMS...

407

Determination of stability constants of U(VI), Np(VI) and Pu(VI) with chloride ions by extraction chromatography  

Microsoft Academic Search

The complex formation of U(VI), Np(VI) and Pu(VI) with chloride ions was studied in HClO4?HCl solutions at ionic strength of 2.0 and [H+]=2.0M by the method of extraction chromatography using dilute HDEHP as the stationary phase.

L. Bednarczyk; I. Fidelis

1978-01-01

408

Soluble arsenic and selenium species in fly ash\\/organic waste-amended soils using ion chromatography-inductively coupled plasma mass spectrometry  

Microsoft Academic Search

Mixing coal fly ash with an organic waste increases macronutrient content and may make land application of fly ash a viable disposal alternative. However, trace element chemistry of these mixed waste products warrants investigation. Speciation of As and Se in soil solutions of fly ash-, poultry litter- and sewage sludge-amended soils was determined over a 10-day period by ion chromatography

B. P. Jackson; W. P. Miller

1999-01-01

409

Closed tube sample introduction for gas chromatography–ion mobility spectrometry analysis of water contaminated with a chemical warfare agent surrogate compound  

Microsoft Academic Search

Ion mobility spectrometry (IMS) is a proven technology for detection of vapor phase chemical warfare agents. The technology is suitable for field portable instrumentation due to its small size, high sensitivity, speed of analysis, and low power consumption. However, it suffers from a limited dynamic range and potential difficulties in identifying compounds in complex matrices. The use of gas chromatography

Richard P. Erickson; Ashish Tripathi; Waleed M. Maswadeh; A. Peter Snyder; Philip A. Smith

2006-01-01

410

EVALUATION OF GAS CHROMATOGRAPHY COUPLED WITH ION MOBILITY SPECTROMETRY FOR MONITORING VINYL CHLORIDE AND OTHER CHLORINATED AND AROMATIC COMPOUNDS IN AIR SAMPLES  

EPA Science Inventory

The objective of this research was to evaluate, in the laboratory, the potential of gas chromatography/ion mobility spectrometry (GC/IMS) for monitoring vinyl chloride and other organic compounds in air samples in the field. It was determined that GC/IMS has the potential to dire...

411

Tandem Immobilized Metal-Ion Affinity Chromatography\\/Immunoaffinity Purification of His-tagged Proteins— Evaluation of Two Anti-His-Tag Monoclonal Antibodies  

Microsoft Academic Search

A tag comprising four to six histidines genetically fused to the protein of interest (His-tag) has been widely used to purify proteins by immobilized metal-ion affinity chromatography (IMAC). Here we report the utilization of the same tag twice in series, first for IMAC and subsequently for immunoaffinity purification. Both steps are based on completely different physical principles and can therefore

Kristian M. Müller; Katja M. Arndt; Konrad Bauer; Andreas Plückthun

1998-01-01

412

Profiling the indole alkaloids in yohimbe bark with ultra-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry  

Technology Transfer Automated Retrieval System (TEKTRAN)

An ultra-high performance liquid chromatography-ion mobility- quadrupole time-of-flight mass spectrometry (UHPLC-IM-QTOF-MS) method was developed for profiling the indole alkaloids in yohimbe bark. Many indole alkaloids with the yohimbine core structure, plus methylated, oxidized, and reduced speci...

413

Exclusive processes in electron-ion collisions in the dipole formalism  

NASA Astrophysics Data System (ADS)

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.; Carvalho, F.; Gonçalves, V. P.

2013-03-01

414

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  

Microsoft Academic Search

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, this MS\\/MS technique increases throughput by eliminating the long pump-down delay associated with gas

Andrey N. Vilkov; Bogdan Bogdanov; Liljiana Pasa-Tolic; David C. Prior; Gordon A. Anderson; Christophe D. Masselon; Ronald J. Moore; Richard D. Smith

2004-01-01

415

Ion exchange chromatography and radioimmunoassay procedure for measuring opioid peptides and substance P  

SciTech Connect

The measurements of peptides of the enkephalin, dynorphin and substance P systems is complicated by the number of possible precursor fragments and degradation products that might cross-react with the antisera. By using an ion-exchanger step before radioimmunoassay one can reduce the possibility that observed peptide levels are due to precursors or metabolites. The ion-exchanger method runs with good recovery and its main advantage is that many samples can be run in parallel. The recovery from the ion-exchanger was similar using two different homogenizing media, whereas the measured endogenous levels of (Met) and (Leu)enkephalin were 3-4 fold higher with 1M acetic acid than when a 1:1 MeOH/HCl mixture was used for tissue extraction.

Bergstroem, L.; Christensson, I.; Folkesson, R.; Stenstroem, B.; Terenius, L.

1983-10-01

416

[Simultaneous separation of organic acid and organic salts by electrostatic ion chromatography].  

PubMed

The electrostatic ion chromatographic column was prepared by coating conjugated acid salt micelles on the surface of octadecyl silica stationary phase. Pure water was used as mobile phase, and the conductance detector was connected on-line to electrostatic ion chromatograph. The conditions under which organic acid and organic salts were detected were studied. The mechanism for the above separation is discussed. Sodium benzoate and citric acid in Lichee drink were separated and determined. This method is rapid, simple with little interference and good reproducibility without any pollution since the mobile phase is water. This is an environmental friendly analytical method. PMID:12545440

Shen, G J; Yang, R F; Yu, A M

2001-09-01

417

How does roasting affect the antioxidants of a coffee brew? Exploring the antioxidant capacity of coffee via on-line antioxidant assays coupled with size exclusion chromatography.  

PubMed

During coffee roasting major changes occur in coffee bean composition. Among others dark coloured melanoidins are formed, which are high molecular weight Maillard reaction products. A new approach is presented here to monitor the influence of roasting conditions on the antioxidant capacity of melanoidins and chlorogenic acids (CGAs) in a coffee brew. Validated Folin-Ciocalteu (FC) and ABTS assays were used as on-line antioxidant assays coupled (post-column) with high performance size-exclusion chromatography (HPSEC). HPSEC enabled the separation of melanoidins from CGAs and the determination of the antioxidant capacity of each fraction, within a total elution time of 25 min. Besides the on-line assay measurements, both assays were also applied off-line with flow injection analysis (FIA). The maximum antioxidant capacity was determined to be at a light-to-medium roast degree, measured with both ABTS-FIA and FC-FIA assays as well as on-line ABTS assay. With FC on-line assay the maximum was found to be at a very light roast degree. Based on the peak areas obtained with the new coupled technique the roasting effects on the variability of melanoidin and CGA contents in coffee brews were studied. The majority of melanoidins are already formed in the early stage of the roasting process and the relative contribution of melanoidins to the total antioxidant capacity increases towards darker roasts, mainly because CGAs degrade during roasting. A new parameter, the ratio of melanoidin to CGA peak area, was introduced as a possible predictor of the roast degree. PMID:23592006

Smrke, Samo; Opitz, Sebastian E W; Vovk, Irena; Yeretzian, Chahan

2013-04-17

418

Human growth hormone association and binding study in vitro: high performance size exclusion chromatography and radioimmunoassay-measured levels in plasma of normal and acromegalic subjects.  

PubMed

Human growth hormone (hGH), like other protein hormones, consists of several molecular forms both in the pituitary and in plasma. In recent years carrier proteins have been detected and studied for growth hormone, using different experimental approaches. In the present study we have attempted to investigate whether hGH could be separated and identified in molecular or aggregated forms using high performance size exclusion chromatography and a small plasma sample, without particular treatment, in order to investigate specific hGH-binding proteins in normal as well as in acromegalic subjects. Results showed that it was possible to observe binding or/and the formation of a complex between free hormone and other molecules that could be specific binding proteins. Equilibrium was reached in a few minutes (7-10 min) and was reversible, as observed with labelled hormone using low and high concentrations of hGH in the incubation medium. At 37 degrees C the associated form at equilibrium was 30% of the total (measured as percent of total radioactivity with labelled hormone) in a plasma medium in which the original growth hormone was absent. Acromegalic plasma demonstrated that the percent of the associated form (namely the 80-kDa form) was less than that in normal humans. This may be due to the fact that capacity binding and competition between labelled and non-labelled growth hormone were favorable to the non-labelled form, if only for the high concentrations in this type of pathology. Therefore our results seem to be in agreement with the hypothesis that acromegalic subjects do not lack this aggregation capacity. PMID:2078923

De Palo, E; Gatti, R; Sicolo, N; De Palo, C

1990-01-01

419

High-resolution determination of {sup 147}Pm in urine using dynamic ion-exchange chromatography  

SciTech Connect

Ion exchange preconcentration followed by HPLC purification prior to scintillation counting was used to measure the concentration of {sup 147}Pm in urine. the detection limit for this method was found to be 0.1 Bq (3 fg) of {sup 147}Pm in 500 ml of urine.

Elchuk, S.; Lucy, C.A.; Burns, K.I. [Chalk River Labs., Ontario (Canada)

1992-10-15

420

Use of ion chromatography for the measurement of organic acids in fruit juices  

Microsoft Academic Search

A gradient ion chromatographic method to separate and determine main organic acids in fruit juices was developed. The method allows the separation of organic anions on Dionex OMNI PAC PAX-500 column by NaOH gradient elution and conductometric detection. The main organic acids of fruit juices (citric, malic, tartaric) were separated together with other less abundant acids. More than 500 samples

G. Saccani; S. Gherardi; A. Trifirò; C. Soresi Bordini; M. Calza; C. Freddi

1995-01-01

421

Concentration of Methylamine and Ethylamine Salts measured by a particle into liquid sampler and Ion Chromatography  

Technology Transfer Automated Retrieval System (TEKTRAN)

A Particle-Into-Liquid Sampler (PILS) and ion chromatographs (ICs) were used to detect the concentration of methylamine salts associated with atmospheric particulate matter reactions in a smog chamber. The smog chamber is located at U.C. Riverside’s College of Engineering Center for Environmental Re...

422

Reverse Phase Ion-Pairing Chromatography at Pressures Up to 345 Mpa.  

National Technical Information Service (NTIS)

The effects of pressure up to 345 MPa (50,000 psi) on a reverse phase ion-pairing system were studied in 50% methanol-water. Retention increased by a factor of 3.2 for methyl orange when the pressure was increased to 241 MPa (30,000 psi) and still larger ...

G. Prukop L. G. Rogers

1977-01-01

423

METHOD FOR THE DETERMINATION OF PERCHLORATE ANION IN PLANT AND SOLID MATRICES BY ION CHROMATOGRAPHY  

EPA Science Inventory

A standardized method for the analysis of perchlorate in plants was developed, based on dry weight, and applied to the analysis of plant organs, foodstuffs, and plant products. The procedure greatly reduced the ionic interferences in water extracts of plant materials. Ion chro...

424

Separacao de tracos de plutonio por cromatografia de troca ionica. (Plutonium removal by ion exchange chromatography).  

National Technical Information Service (NTIS)

A study for plutonium recovery at trace level from uranium solutions by ion exchange technique is presented. Plutonium retention > 99,5% onto strong anionic resin, AG-X8, from nitric acid solutions and a 92% recovery using 0,4 H NO(sub 3) at 60(sup 0) C a...

B. F. Araujo H. T. Matsuda E. I. Carvalho I. C. Araujo

1991-01-01

425

DETERMINATION OF BROMATE IN DRINKING WATERS BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION  

EPA Science Inventory

Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic colu...

426

Determination of four tobacco-specific nitrosamines in mainstream cigarette smoke by gas chromatography/ion trap mass spectrometry.  

PubMed

A specific and sensitive method was developed and validated to quantitatively analyze four tobacco-specific nitrosamines (TSNAs) in the particulate phase of mainstream cigarette smoke. Cigarette smoke particulate matter was collected according to ISO 4387. The particulate matter was extracted with acetic ether, cleaned up with a Supelclean ENVI-Carb silod-phase extraction (SPE) cartridge, concentrated under the protection of nitrogen and analyzed by gas chromatography (GC)/ion trap mass spectrometry (MS) with a very-low-flow-loss column (VF-17 MS) in MS(n) mode using N-nitrosopentyl-3-picolylamine (NNPA) as an internal standard. TSNAs were identified by chromatographic retention time, matching the spectra of the standards and the samples and the consistency of the ratio of the abundance of the ions detected in the standards and the samples. Limits of detection of each TSNA varied from 0.01 to 0.06 ng/cig. A linear calibration range for this method is large enough to measure TSNA levels in cigarette smoke. The recovery of each TSNA was from 91.5 to 102.7%. The method achieved excellent reproducibility (RSD: 1.8-4.8% for intra-assay, 3.4-7.1% for inter-assay). It also shows no evidence of artifact formation. This method is very suitable for the routine detection of TSNAs in mainstream cigarette smoke. PMID:18008390

Zhou, Jun; Bai, Ruoshi; Zhu, Yongfa

2007-01-01

427

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

428

Analysis of hexavalent chromium in Colla corii asini with on-line sample pretreatment valve-switching ion chromatography.  

PubMed

An ion chromatography (IC) system with on-line sample pretreatment using valve-switching technique was developed for the determination of hexavalent chromium (Cr(VI)) in Colla corii asini. Colla corii asini is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a collection loop to analytical columns, with matrix eliminated on-line. Under the optimized separation conditions, the method showed good linearity (r=0.9998) in the range of 0.004-1.0mg/L and satisfactory repeatability (RSD<3%, n=6). The limit of detection (LOD) was 1.4?g/L (S/N=3). The average spiked recoveries of Cr(VI) were 93.4-102.0%. The result showed that the on-line sample pretreatment IC system was convenient and practical for the determination of trace Cr(VI) in Colla corii asini samples. PMID:23891376

Yang, Yuling; He, Jie; Huang, Zhongping; Zhong, Naifei; Zhu, Zuoyi; Jiang, Renyu; You, Jinghua; Lu, Xiuyang; Zhu, Yan; He, Shiwei

2013-07-11

429

Simultaneous determination of 13 components in oxidative hair dyes by high-performance chromatography using an ion-pair reagent.  

PubMed

A reliable high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of 13 dye intermediates, including benzenediamines, aminophenols, benzenediols, naphthalenediol, and diaminopyridine, in oxidative hair dyes. Samples were extracted with 50% ethanol by adding sodium dithionite to prevent oxidation. The influences of buffer type, buffer pH, ion-pair reagent, and elution gradient were studied. A C18 column with aqueous compatibility and acetonitrile-citric acid mobile phase system (pH 2.6) with sodium 1-octanesulfonate as ion-pair reagent were selected for the separation of target compounds. Detection was performed by a diode array detector, (DAD) and two different wavelengths (280 and 331 nm) were used for quantification. Results showed that 13 dye intermediates got good separation within 25 min. The detection limits of these compounds were in the range of 0.2-2 mg/l. The calibration curves were linear within 2-500 mg/l with 0.999 as a typical correlation coefficient. The recoveries of target compounds in hair dyes ranged from 81.7% to 102.0% with four addition levels. The method described was validated by five different laboratories and successfully applied to the analysis of commercial oxidative hair dyes. PMID:23089354

Lai, Ying; Wang, Honghui; Dong, Qingmu; Chen, Hexiu; Lin, Rui; Cai, Yanping

430

Urine iodide determination by ion-pair reversed-phase high performance liquid chromatography and pulsed amperometric detection.  

PubMed

A sensitive and specific ion-pair reversed-phase high performance liquid chromatography (HPLC) method for urinary iodine analysis is described. This method is based on pulsed amperometric detection (PAD) using a silver working electrode (HPLC-PAD), which improves peak shape, electrode stability as well as linearity and reproducibility. A two-step extraction process consisting of solid phase extraction (SPE) and liquid-liquid extraction with dichloromethane was added in order to improve sample purification which is essential with the use of PAD. Treated samples were eluted on a C18 column, using a phosphate buffer containing ion-pairing reagent tetrabutylammonium and 5% MeOH. The calibration standard curves were linear up to 500 ?g/L and within-run and between-run coefficients of variation (CVs) were <6% with the quantification limit fixed at 6 ?g/L. Accuracy, expressed as recovery, ranged from 94% to 104%. Comparison with the Technicon AutoAnalyzer acid digestion (AA) method resulted in a high correlation (r=0.9916). Due to a low quantification limit and high sample throughput, the proposed technique appears suitable for both epidemiological and clinical follow-up studies. PMID:22967590

Nguyen, Vo Thanh Phuong; Piersoel, Virginie; El Mahi, Tarik

2012-06-27

431

Analysis of the neurotoxic plasticizer n-butylbenzenesulfonamide by gas chromatography combined with accurate mass selected ion monitoring.  

PubMed

The plasticizer, n-butylbenzenesulfonamide (NBBS), is reported to be neurotoxic when inoculated intracisternally or intraperitoneally into rabbits. Because NBBS is commonly used in the production of polyamide (nylon) plastics and is soluble in water, the disposal of NBBS-containing plastics in landfill sites could result in NBBS appearing in the leachate. Further, NBBS could also be leached from packaging into their contents. To allow us to examine the risks posed by NBBS in the environment, we have developed a quantitative assay for this compound. The assay employs a one-step extraction into dichloromethane followed by gas chromatography with accurate mass selected ion recording. The assay incorporates [13C6]NBBS as an internal standard to allow precise quantitation, and four separate ion chromatograms are recorded. NBBS was found in some Australian domestic solidwaste landfill leachate (from less than 0.3 to 94.6 ng/mL), but ground water in the vicinity of a landfill had only trace quantities of NBBS. NBBS was also quantitated in some bottled and cask wines, and levels varied from not detected to 2.17 ng/mL (n = 14). Additional studies are required to assess the public health risks associated with the use of NBBS as a plasticizer. PMID:7861748

Duffield, P; Bourne, D; Tan, K; Garruto, R M; Duncan, M W

432

[Determination of 1-hydroxyethylidene-1,1-diphosphonic acid in recycle-cooling water by ion chromatography].  

PubMed

1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) is usually used as a scale and corrosion inhibitor in recycle-cooling water for steel industry. The quick and accurate analysis of HEDP concentration in water is of importance to control the inhibitor adding program. However, the common method for HEDP analysis, which determines the total phosphate in water samples, may suffer the serious problem of incorrectly including degraded HEDP as the active HEDP reagent. In this study, the method of the determination of HEDP in recycle-cooling water by ion chromatography was investigated. The chromatographic parameters, including elution and detection, were optimized. The separation was achieved on an IonPac AS14A column with NaOH solution of 80 mmol/L as the eluent at a flow rate of 1. 0 mL/min, and the detection was performed by a suppressed conductivity detection mode with the injection volume of 25 microL. The method showed good linearity within the range of 0. 25 and 25 mg/L with an average recovery of 102%. The detection limit of the method reached as low as 0. 1 mg/L. The relative standard deviations for 0. 25 and 0. 5 mg/L HEDP standard solutions were 4. 7% and 3. 5% (n = 13) , respectively. The method has been applied for the determination of HEDP in recycle-cooling water samples with the advantages of being simple, fast, sensitive, and interference free. PMID:17580697

Ma, Jian; Yuan, Dongxing; Guan, Bin; Yang, Rong; Ge, Laowei

2007-03-01

433

Simultaneous determination of fluoride, chloride, sulfate, phosphate, monofluorophosphate, glycerophosphate, sorbate, and saccharin in gargles by ion chromatography*  

PubMed Central

Simple, reliable and sensitive analytical methods to determine anticariogenic agents, preservatives, and artificial sweeteners contained in commercial gargles are necessary for evaluating their effectiveness, safety, and quality. An ion chromatography (IC) method has been described to analyze simultaneously eight anions including fluoride, chloride, sulfate, phosphate, monofluorophosphate, glycerophosphate (anticariogenic agents), sorbate (a preservative), and saccharin (an artificial sweetener) in gargles. In this IC system, we applied a mobile phased gradient elution with KOH, separation by IonPac AS18 columns, and suppressed conductivity detection. Optimized analytical conditions were further evaluated for accuracy. The relative standard deviations (RSDs) of the inter-day’s retention time and peak area of all species were less than 0.938% and 8.731%, respectively, while RSDs of 5-day retention time and peak area were less than 1.265% and 8.934%, respectively. The correlation coefficients for targeted analytes ranged from 0.999 7 to 1.000 0. The spiked recoveries for the anions were 90%~102.5%. We concluded that the method can be applied for comprehensive evaluation of commercial gargles.

Zhang, Yan-zhen; Zhou, Yan-chun; Liu, Li; Zhu, Yan

2007-01-01

434

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.

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

2011-01-01

435

Classification and dating of black gel pen ink by ion-pairing high-performance liquid chromatography.  

PubMed

A novel approach for classification and dating of the black gel pen ink entries on document was developed based on ion-pairing high-performance liquid chromatography (IP-HPLC). Ninety-three black gel pens were collected and divided into two groups, dye-based and pigment-based, by preliminary solubility test. The chromatographic conditions for separation of the dye-based black gel pen inks were optimized and the dye components in inks were satisfactorily separated by using 40 mmol/L tetrabutylammonium bromide as ion-pairing reagent. According to the number and the chromatographic retention times of the main dye components, the 50 dye-based inks were categorized into four classes. The inks within a class can be further identified by the percentage of each dye component. The compositional changes of the dye components in the black gel pen ink entries on paper were investigated in light and natural aging conditions and it has been found that the dye components in the ink entries underwent obvious decomposition, and the decomposing extent of the dye components was related to the aging time. The results can provide scientific evidences for dating of the suspicious black gel pen ink entries on documents. PMID:17028000

Liu, Yi-Zi; Yu, Jing; Xie, Meng-Xia; Liu, Yuan; Han, Jie; Jing, Ting-Ting

2006-10-09

436

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

437

A new measurement technique of peroxyacetyl nitrate at parts per trillion by volume levels: Gas chromatography\\/negative ion chemical ionization mass spectrometry  

Microsoft Academic Search

A new technique for measuring peroxyacetyl nitrate (PAN) at parts per trillion by volume (pptv) levels has been developed using gas chromatography with negative ion chemical ionization mass spectrometry (GC\\/NICI MS). Four fragment ions, CH3C(O)O- (mass-to-charge ratios (m\\/z)=59), NO3-(m\\/z=62), CH3C(O)OO-(m\\/z=75), and NO2-(m\\/z=46), were identified by NICI mass spectra. NO3-(m\\/z=62) was used in selected ion monitoring (SIM) mode among these fragment

Hiroshi Tanimoto; Jun Hirokawa; Yoshizumi Kajii; Hajime Akimoto

1999-01-01

438

Quantitative determination of glycopyrrolate in human plasma by liquid chromatography–electrospray ionization mass spectrometry: The use of a volatile ion-pairing agent during both liquid–liquid extraction and liquid chromatography  

Microsoft Academic Search

The work presented here deals with the development of a quantitative tool for the determination of the quaternary ammonium anticholinergic glycopyrrolate in human plasma samples. Mepenzolate was used as an internal standard. The plasma samples were subjected to a suitable sample clean-up consisting of a simple and relatively fast, two step liquid–liquid ion-pair extraction procedure. The chromatography, using the same

M. L. Storme; R. S. t’Kindt; W. Goeteyn; K. Reyntjens; J. F. Van Bocxlaer

2008-01-01

439

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

440

Determination of sinigrin in vegetable seeds by online microdialysis sampling coupled to reverse-phase ion-pair liquid chromatography.  

PubMed

A hollow fiber microdialysis sampling coupled online to ion-pair liquid chromatography was investigated as an alternative to sample pretreatment for the direct determination of sinigrin in cruciferous vegetables without desulfation. After microdialysis, the dialysate was online injected into the chromatographic system to analyze the sinigrin with UV detection at 227 nm. Parameters affecting the microdialysis efficiency, such as flow rate, polarity modifier, pH in perfusion stream, pH, and salt added in sample solution, were studied. Through ion suppression in the donor phase and ion-pair formation in the acceptor phase, the microdialysis efficiency of sinigrin was enhanced. Experimental results revealed that the microdialysis of a sample solution (pH 2.0) using 0.1 M tetrabutylammonium (pH 12) as a perfusate at 10 microL/min flow rate maximized the extraction efficiency. Detection was linear in the concentration of 1.0-100 mg/L with a detection limit of 0.3 mg/L. Three seed samples were analyzed, with sinigrin at 49.8 (3.15% RSD), 20.0 (4.43% RSD), and 19.8 mg/g (4.22% RSD) for brussels, cauliflower, and cabbage, respectively. When 40 mg/g sinigrin was spiked in brussels seed powder, the recovery was 102.4% with 3.15% RSD (n = 3). The proposed method was proven to provide a very simple, rapid, and eco-friendly procedure to determine sinigrin in the seeds of cruciferous vegetables. PMID:20329796

Lin, Tsai-Hung; Huang, Jenn-Wen; Kumar, Ponnusamy Vinoth; Jen, Jen-Fon

2010-04-28

441

Purification of two muscle enzymes by chromatography on immobilized ferric ions.  

PubMed

Two enzymes, glycogen phosphorylase and lactate dehydrogenase, were purified simultaneously in a single step. Ferric ions immobilized on a chelating gel were used as the adsorbent. Adsorption and desorption steps were accomplished by changes in buffer composition. The recoveries were better than 80% and the capacities were about 5 mg of protein per milliliter of adsorbent. The procedure worked well both on a small and on a preparative scale. The homogeneity of the purified enzymes was checked by FPLC. PMID:2775499

Chaga, G; Andersson, L; Ersson, B; Porath, J

1989-08-01

442

Dynamic ion exchange chromatography for the determination of number of fissions in uranium dioxide fuels  

Microsoft Academic Search

The liquid chromatographic determination of the fission monitor ¹³⁹La has been examined for the determination of the number of fissions and burnup in UOâ fuels. Lanthanum was separated from the fuel and other fission products on a reversed phase dynamically modified with 1-octanesulfonate, and eluted metal ions were detected after an on-line postcolumn reaction with Arsenazo III. The relative standard

R. M. Cassidy; S. Elchuk; N. L. Elliot; L. W. Green; C. H. Knight; B. M. Recoskie

1986-01-01

443

Determination of oxalate, sulfate and nitrate in honey and honeydew by ion-chromatography  

Microsoft Academic Search

An ion chromatographic method for determining the anions oxalate, sulfate and nitrate in honey and honeydew samples is described. To prevent matrix interference and to isolate the anions a clean-up step using solid-phase extraction on anionic cartridges and eluting with a 0.01 M chromate solution is recommended. The anions are separated on an anionic column with a mobile phase of

J. L Bernal; J. C Diego; L. A Gómez; J. M Ruiz; M Higes

2000-01-01

444

Determination of sulfonic acids and alkylsulfates by ion chromatography in water  

Microsoft Academic Search

A fast ion chromatographic method with suppressed conductivity detection has been developed for the simultaneous determination of methane-, ethane-, 1-propane-, 1-butane-, 1-pentane-, 1-hexane-, 1-heptane-, 1-octane-, 1-nonane-, 1-decane-, 1-dodecane-, dodecylbenzene-, p-toluene-, benzenesulfonic acids, octylsulfate and dodecylsulfate in water samples. Due to the high number of analytes and their heterogeneity, the effect of the mobile phase parameters (NaOH, CH3OH and CH3CN concentration)

Maria Concetta Bruzzoniti; Rosa Maria De Carlo; Corrado Sarzanini

2008-01-01

445

Ion exchange chromatography as a selective pre-concentration method for PIXE analysis of urine  

NASA Astrophysics Data System (ADS)

A cation exchange resin, Chelex 100, has been used to separate and preconcentrate trace metal ions in urine. The separation from macro-elements is good and the concentration factor for trace metals is about 50. The detection limits are decreased by a factor between 20 and 40 compared to direct analysis of urine which enables the analysis of metals with low level of natural occurrence.

Pakarinen, Pirjo; Pallon, Jan; Akselsson, Roland

1984-04-01

446

Ion chromatography as a tool for the investigation of unsymmetrical hydrazine degradation in soils  

Microsoft Academic Search

A new procedure for the determination of 1,1-dimethylhydrazine (UDMH) in soil samples was developed. This involves the distillation of UDMH from an alkaline suspension of soil and ion chromatographic analysis of the distillate. The separation was performed on a silica cation-exchanger column with ammonium acetate buffer solution as mobile phase and amperometric detection at +1.2?V. Hydrazine (Hy) and methylhydrazine (MH),

Alexander D. Smolenkov; Pavel P. Krechetov; Andrey V. Pirogov; Tatiana V. Koroleva; Alexander A. Bendryshev; Oleg A. Shpigun; Maria M. Martynova

2005-01-01

447

Negative ion chemical ionization gas chromatography/mass spectrometry of valproic acid metabolites.  

PubMed

A negative ion chemical ionization (NICI) gas chromatographic/mass spectrometric method is described for the identification of 15 valproic acid (VPA) metabolites as their pentafluorobenzyl derivatives. Samples analyzed were serum, urine and saliva taken from a volunteer on VPA at steady state and also given selected doses of (2H6)VPA. Metabolite peaks were identified by comparison to synthetic standards. All the metabolites, like the parent drug, produced abundant [M - 181]- ions, except 3-keto VPA, which gave an [M - 181 - CO2]- ion. Using the NICI method, two new VPA metabolites were identified. One of these metabolites was characterized as 4'-keto-2-ene VPA by synthesis, while the second one appeared to be a positional isomer of 4'-keto-2-ene VPA. The sensitivity of the method was also sufficient to detect metabolites of VPA in saliva. The ratio of the levels of (Z)-2-ene VPA to (E)-2-ene VPA was much greater in saliva than in serum, suggesting stereoselective plasma protein binding or transport of these two metabolites. The lower limit of detection for the quantification of VPA in serum or saliva was 2 ng ml-1. PMID:2508808

Kassahun, K; Burton, R; Abbott, F S

1989-10-01

448

Determination of trace level perchlorate in drinking water and ground water by ion chromatography.  

PubMed

Ammonium perchlorate, a key ingredient in solid rocket propellants, has recently been found in ground and surface waters in the USA in a number of states, including California, Nevada, Utah, and West Virginia. Perchlorate poses a health risk and preliminary data from the US Environmental Protection Agency reports that exposure to less than 4-18 micrograms/l provides adequate human health protection. An ion chromatographic method was developed for the determination of low microgram/l levels of perchlorate in drinking and ground waters based on a Dionex IonPac AS11 column, a 100 mM hydroxide eluent, large loop (1000 microliters) injection, and suppressed conductivity detection. The method is free of interferences from common anions, linear in the range of 2.5-100 micrograms/l, and quantitative recoveries were obtained for low microgram/l levels of perchlorate in spiked drinking and ground water samples. The method detection limit of 0.3 microgram/l permits quantification of perchlorate below the levels which ensure adequate health protection. A new polarizable anion analysis column, the IonPac AS16, and its potential applicability for this analysis is also discussed. PMID:10457473

Jackson, P E; Laikhtman, M; Rohrer, J S

1999-07-30

449

Trace level detection of chlorinated paraffins in biological and environmental samples, using gas chromatography/mass spectrometry with negative-ion chemical ionization.  

PubMed

A method is described for detection of chlorinated paraffins (CPs) in biological and environmental samples. Sample preparation includes sulfuric acid treatment followed by adsorption chromatography on alumina, which yields the CPs in one fraction that is almost free of interfering material. Using gas chromatography/mass spectrometry with negative-ion chemical ionization, the limit of detection is 5 ng (corresponding to the lower ppb range). CP levels of 30 ppm, 200 ppb, and 5 ppb were found in sewage sludge, human fat, and sediment, respectively. PMID:4019363

Schmid, P P; Müller, M D

450

Critical Evaluation of Acetylcholine Determination in Rat Brain Microdialysates using Ion-Pair Liquid Chromatography with Amperometric Detection  

PubMed Central

Liquid chromatography with amperometric detection remains the most widely used method for acetylcholine quantification in microdialysis samples. Separation of acetylcholine from choline and other matrix components on a microbore chromatographic column (1 mm internal diameter), conversion of acetylcholine in an immobilized enzyme reactor and detection of the produced hydrogen peroxide on a horseradish peroxidase redox polymer coated glassy carbon electrode, achieves sufficient sensitivity for acetylcholine quantification in rat brain microdialysates. However, a thourough validation within the concentration range required for this application has not been carried out before. Furthermore, a rapid degradation of the chromatographic columns and enzyme systems have been reported. In the present study an ion-pair liquid chromatography assay with amperometric detection was validated and its long-term stability evaluated. Working at pH 6.5 dramatically increased chromatographic stability without a loss in sensitivity compared to higher pH values. The lower limit of quantification of the method was 0.3 nM. At this concentration the repeatability was 15.7%, the inter-day precision 8.7% and the accuracy 103.6%. The chromatogr