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Sample records for ion exclusion chromatography

  1. Ion-Exclusion Chromatography for Analyzing Organics in Water

    NASA Technical Reports Server (NTRS)

    Sauer, Richard; Rutz, Jeffrey A.; Schultz, John R.

    2006-01-01

    A liquid-chromatography technique has been developed for use in the quantitative analysis of urea (and of other nonvolatile organic compounds typically found with urea) dissolved in water. The technique involves the use of a column that contains an ion-exclusion resin; heretofore, this column has been sold for use in analyzing monosaccharides and food softeners, but not for analyzing water supplies. The prior technique commonly used to analyze water for urea content has been one of high-performance liquid chromatography (HPLC), with reliance on hydrophobic interactions between analytes in a water sample and long-chain alkyl groups bonded to an HPLC column. The prior technique has proven inadequate because of a strong tendency toward co-elution of urea with other compounds. Co-elution often causes the urea and other compounds to be crowded into a narrow region of the chromatogram (see left part of figure), thereby giving rise to low chromatographic resolution and misidentification of compounds. It is possible to quantitate urea or another analyte via ultraviolet- and visible-light absorbance measurements, but in order to perform such measurements, it is necessary to dilute the sample, causing a significant loss of sensitivity. The ion-exclusion resin used in the improved technique is sulfonated polystyrene in the calcium form. Whereas the alkyl-chain column used in the prior technique separates compounds on the basis of polarity only, the ion-exclusion-resin column used in the improved technique separates compounds on the basis of both molecular size and electric charge. As a result, the degree of separation is increased: instead of being crowded together into a single chromatographic peak only about 1 to 2 minutes wide as in the prior technique, the chromatographic peaks of different compounds are now separated from each other and spread out over a range about 33 minutes wide (see right part of figure), and the urea peak can readily be distinguished from the other peaks. Although the analysis takes more time in the improved technique, this disadvantage is offset by two important advantages: Sensitivity is increased. The minimum concentration of urea that can be measured is reduced (to between 1/5 and 1/3 of that of the prior technique) because it is not necessary to dilute the sample. The separation of peaks facilitates the identification and quantitation of the various compounds. The resolution of the compounds other than urea makes it possible to identify those compounds by use of mass spectrometry.

  2. Instrumentation: Ion Chromatography.

    ERIC Educational Resources Information Center

    Fritz, James S.

    1987-01-01

    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)

  3. Highly sensitive determination of hydrazine ion by ion-exclusion chromatography with ion-exchange enhancement of conductivity detection.

    PubMed

    Mori, Masanobu; Tanaka, Kazuhiko; Xu, Qun; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi

    2004-06-11

    An ion-exclusion chromatography method with ion-exchange enhancement of conductivity was developed for the selective separation and sensitive determination of hydrazine ion from alkali/alkaline earth metal cations and ammonium ion. Hydrazine ion was separated by ion-exclusion/penetration effect from other cations on a weakly basic anion-exchange column in the OH- form (TSKgel DEAE-5PW). Moreover, two different ion-exchange resin columns were inserted between the separating column and conductimetric detector in order to improve the sensitivity of hydrazine ion. The first enhancement column packed with a strongly basic anion-exchange resin in the SO4(2-) form (TSKgel SAX) for hydrazine ion can convert from N2H5OH to (N2H5)2SO4. Moreover, the second enhancement column packed with a strongly acidic cation-change resin in the H+ form (TSKgel SCX) can convert to H2SO4. As a result, the sensitivity of hydrazine ion using two conductivity enhancement columns could be 26.8-times greater than using the separating column alone. This method was effectiveness also for the enhancement of ammonium ion (6.1-times) and sodium ion (1.2-times). The calibration graph of hydrazine ion detected as H2SO4 was linear over the concentration range of 0.001-100 ppm (r2 = 0.9988). The detection limit of hydrazine ion in this system was 0.64 ppb. Therefore, hydrazine ion in real boiler water sample could be accurately determined, avoiding the interference of other cations. PMID:15250415

  4. Water ICE: Ion Exclusion Chromatography of Very Weak Acids with a Pure Water Eluent.

    PubMed

    Liao, Hongzhu; Shelor, C Phillip; Dasgupta, Purnendu K

    2016-05-01

    Separation of ions or ionizable compounds with pure water as eluent and detecting them in a simple fashion has been an elusive goal. It has been known for some time that carbonic acid can be separated from strong acids by ion chromatography in the exclusion mode (ICE) using only water as the eluent. The practice of water ICE was shown feasible for very weak acids like silicate and borate with a dedicated element specific detector like an inductively coupled plasma mass spectrometer (ICPMS), but this is rarely practical in most laboratories. Direct conductometric detection is possible for H2CO3 but because of its weak nature, not especially sensitive; complex multistep ion exchange methods do not markedly improve this LOD. It will clearly be impractical in acids that are weaker still. By using a permeative amine introduction device (PAID, Anal. Chem. 2016 , 88 , 2198 - 2204 ) as a conductometric developing agent, we demonstrate that a variety of weak acids (silicate, borate, arsenite, cyanide, carbonate, and sulfide) cannot only be separated on an ion exclusion column, they can be sensitively detected (LODs 0.2-0.4 μM). We observe that the elution order is essentially the same as that on a nonfunctionalized poly(styrene-divinylbenzene) column using 1-10% acetonitrile as eluent and follows the reverse order of the polar surface area (PSA) of the analyte molecules. PSA values have been widely used to predict biological transport of pharmaceuticals across a membrane but never to predict chromatographic behavior. We demonstrate the application of the technique by measuring the silicate and borate depth profiles in the Pacific Ocean; the silicate results show an excellent match with results from a reference laboratory. PMID:27075932

  5. Ion Chromatography.

    ERIC Educational Resources Information Center

    Mulik, James D.; Sawicki, Eugene

    1979-01-01

    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)

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

    PubMed

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

    2013-01-01

    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 μM) than those obtained with conductometric detection (CD) (0.61 - 2.1 μM) 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

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

    SciTech Connect

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

    1994-10-01

    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.

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

    SciTech Connect

    Hartfield, S.; Hester, R.

    1993-12-31

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

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

    PubMed

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

    2002-05-17

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

  10. Effect of the porosity of PS-DVB-copolymers on ion chromatographic behavior in inverse size-exclusion and ion chromatography.

    PubMed

    Füssler, Rainer; Schäfer, Helwig; Seubert, Andreas

    2002-03-01

    Small and highly pressure-stable PS-DVB copolymers of different porosity had been prepared by a two-step swelling procedure which enabled variation of diluent composition, an important characteristic affecting the porosity. The polymers were characterized by inverse size-exclusion chromatography and scanning electron microscopy. Subsequent chloromethylation and amination resulted in anion exchangers suitable for ion chromatography. The pore volume and the pore-size distribution is substantially affected by the fraction of the solvens component in the diluent. It was apparent from scanning electron microscopy that surface structure and the size of the polymer particles was not affected by diluent composition. The functionalization process led to a decrease in pore volume. The pore-size distribution remained unchanged during functionalization, which can be explained in terms of partial closing of all pore sizes. The chromatographic efficiency of the functionalized polymers in ion chromatography was highly dependent on diluent composition and the extent of functionalization was determined by the total pore volume. The composition of the diluent is an excellent tool for optimization of polymers used for the synthesis of surface-functionalized anion exchangers. PMID:11941442

  11. Ion chromatography applications

    SciTech Connect

    Smith, R.E.

    1988-01-01

    This book describes recent advances in ion chromatography and demonstrates how it is used to solve scientific and industrial problems. The basic principles of ion chromatography are explained, including gradient elution of ions and micromembrane suppressors. The various anion and cation exchange columns together with various detection methods and applications of ion chromatography in the environmental and life sciences and industry are reviewed. Over 100 chromatograms which illustrate parameters needed to perform analysis and data on gradient and mobile phase ion chromatography are included.

  12. Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column.

    PubMed

    Ito, Kazuaki; Takayama, Yohichi; Ikedo, Mikaru; Mori, Masanobu; Taoda, Hiroshi; Xu, Qun; Hu, Wenzhi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

    2004-06-11

    The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences. PMID:15250416

  13. Selective determination of ammonium ions by high-speed ion-exclusion chromatography on a weakly basic anion-exchange resin column.

    PubMed

    Mori, Masanobu; Tanaka, Kazuhiko; Helaleh, Murad I H; Xu, Qun; Ikedo, Mikaru; Ogura, Yutaka; Sato, Shinji; Hu, Wenzhi; Hasebe, Kiyoshi

    2003-05-16

    This paper describes an ion-exclusion chromatographic system for the rapid and selective determination of ammonium ion. The optimized ion-exclusion chromatographic system was established with a polymethacrylate-based weakly basic anion-exchange resin column (TSKgel DEAE-5PW) as the separation column, an aqueous solution containing 0.05 mM tetramethylammonium hydroxide (pH 9.10) as eluent with conductimetric detection for the analyte determination. Under the optimum chromatographic conditions, ammonium ion was determined within 2.3 min with a detection limit (S/N=3) better than 0.125 microM. Ammonium ion in rain and river waters was precisely determined using this ion-exclusion chromatographic system. PMID:12830892

  14. Ion Chromatography: An Account of Its Conception and Early Development

    ERIC Educational Resources Information Center

    Small, Hamish

    2004-01-01

    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.

  15. Use of potassium-form cation-exchange resin as a conductimetric enhancer in ion-exclusion chromatography of aliphatic carboxylic acids.

    PubMed

    Iwata, Tomotaka; Mori, Masanobu; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2009-09-15

    In this study, a cation-exchange resin (CEX) of the K(+)-form, i.e., an enhancer resin, is used as a postcolumn conductimetric enhancer in the ion-exclusion chromatography of aliphatic carboxylic acids. The enhancer resin is filled in the switching valve of an ion chromatograph; this valve is usually used as a suppressor valve in ion-exchange chromatography. An aliphatic carboxylic acid (e.g., CH(3)COOH) separated by a weakly acidic CEX column of the H(+)-form converts into that of the K(+)-form (e.g., CH(3)COOK) by passing through the enhancer resin. In contrast, the background conductivity decreases because a strong acid (e.g., HNO(3)) with a higher conductimetric response in an eluent converts into a salt (e.g., KNO(3)) with a lower conductimetric response. Since the pH of the eluent containing the resin enhancer increases from 3.27 to 5.85, the enhancer accelerates the dissociations of analyte acids. Consequently, peak heights and peak areas of aliphatic carboxylic acids (e.g., acetic acid, propionic acid, butyric acid, and valeric acid) with the enhancer resin are 6.3-8.0 times higher and 7.2-9.2 times larger, respectively, than those without the enhancer resin. Calibrations of peak areas for injected analytes are linear in the concentration range of 0.01-1.0mM. The detection limits (signal-to-noise ratio=3) range from 0.10 microM to 0.39 microM in this system, as opposed to those in the range of 0.24-7.1 microM in the separation column alone. The developed system is successfully applied to the determination of aliphatic carboxylic acids in a chicken droppings sample. PMID:19615503

  16. Simultaneous analysis of silicon and boron dissolved in water by combination of electrodialytic salt removal and ion-exclusion chromatography with corona charged aerosol detection.

    PubMed

    Mori, Masanobu; Sagara, Katsuya; Arai, Kaori; Nakatani, Nobutake; Ohira, Shin-Ichi; Toda, Kei; Itabashi, Hideyuki; Kozaki, Daisuke; Sugo, Yumi; Watanabe, Shigeki; Ishioka, Noriko S; Tanaka, Kazuhiko

    2016-01-29

    Selective separation and sensitive detection of dissolved silicon and boron (DSi and DB) in aqueous solution was achieved by combining an electrodialytic ion isolation device (EID) as a salt remover, an ion-exclusion chromatography (IEC) column, and a corona charged aerosol detector (CCAD) in sequence. DSi and DB were separated by IEC on the H(+)-form of a cation exchange resin column using pure water eluent. DSi and DB were detected after IEC separation by the CCAD with much greater sensitivity than by conductimetric detection. The five-channel EID, which consisted of anion and cation acceptors, cathode and anode isolators, and a sample channel, removed salt from the sample prior to the IEC-CCAD. DSi and DB were scarcely attracted to the anion accepter in the EID and passed almost quantitatively through the sample channel. Thus, the coupled EID-IEC-CCAD device can isolate DSi and DB from artificial seawater and hot spring water by efficiently removing high concentrations of Cl(-) and SO4(2-) (e.g., 98% and 80% at 0.10molL(-1) each, respectively). The detection limits at a signal-to-noise ratio of 3 were 0.52μmolL(-1) for DSi and 7.1μmolL(-1) for DB. The relative standard deviations (RSD, n=5) of peak areas were 0.12% for DSi and 4.3% for DB. PMID:26755416

  17. Determination of arsenite, arsenate, and monomethylarsonic acid in seawater by ion-exclusion chromatography combined with inductively coupled plasma mass spectrometry using reaction cell and hydride generation techniques.

    PubMed

    Nakazato, Tetsuya; Tao, Hiroaki; Taniguchi, Tadashi; Isshiki, Kenji

    2002-08-16

    This paper describes a robust and sensitive method for the determination of arsenic species in seawater by ion-exclusion liquid chromatography (LC) combined with inductively coupled plasma mass spectrometry (ICP-MS) using reaction cell and hydride generation (HG) techniques. A good separation of arsenite, arsenate, and monomethylarsonic acid was achieved using an ion-exclusion column packed with a sulfonated polystyrene resin and a dilute nitric acid at pH 2.0 as the eluent, even when a large volume, i.e. 200 mul, of seawater samples containing a large amount of matrix was repeatedly injected. Separations of the chloride ion due to the matrix and arsenic species were partially performed; however, the extensive peak of ArCl due to high content of Cl(-) in a sample overlapped peaks of the three arsenic species on (75)As measurement by ICP-MS. This ArCl polyatomic interference was efficiently eliminated by collision of ArCl molecules with helium in an octopole reaction cell which was introduced prior to a mass spectrometer. Detection limits of the three arsenic species in a sample containing 2% Cl(-), the concentration of which is comparable to that in a seawater sample, by LC-ICP-MS with the octopole reaction system (ORS), ranged from 21 to 25 pg As ml(-1); these values were three-six times lower than those by LC-ICP-MS without ORS. As another technique for ArCl interference elimination, HG prior to ICP-MS was also successfully used not only to reduce the interference but also to improve the detection limits to 3.4-4.5 pg As ml(-1). The developed LC-ICP-ORS-MS and LC-HG-ICP-MS were validated by analyzing a certified reference material (CRM) of seawater. In addition, no serious decrease in analytical performance of present methods was observed in the experimental periods of half a year for LC-ICP-ORS-MS and 1 year for LC-HG-ICP-MS, respectively. The latter method was successfully applied to characterize seasonal variations of three arsenic species in deep seawater and surface seawater. PMID:18968739

  18. Simultaneous determinations of Cr(VI) and Cr(III) by ion-exclusion/cation-exchange chromatography with an unmodified silica-gel column.

    PubMed

    Hirata, Shizuko; Kozaki, Daisuke; Sakanishi, Kinya; Nakagoshi, Nobukazu; Tanaka, Kazuhiko

    2010-01-01

    In order to characterize the ion-exclusion and cation-exchange properties of an unmodified silica-gel column, the retention behaviors of Cr(VI) and Cr(III) ions were investigated using a Develosil 30-5 (150 x 4.6 mm i.d.) in the acidic region. Cr(VI) was separated from other anions by an ion-exclusion and ion-adsorption mechanism, and Cr(III) was separated from other cations with a cation-exchange mechanism. When using 2.0 mM oxalic acid (pH 2.6) as an eluent, a good separation of Cr(VI) and Cr(III) was obtained using conductimetric detection in 12 min. The method was successfully applied to the simultaneous determinations of Cr(VI) and Cr(III) added into tap-water and river-water samples. PMID:20215693

  19. Principles and applications of steric exclusion chromatography.

    PubMed

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

    2012-12-28

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

  20. 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...

  1. Ion Exchange and Liquid Column Chromatography.

    ERIC Educational Resources Information Center

    Walton, Harold F.

    1980-01-01

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

  2. Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin.

    PubMed

    Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Helaleh, Murad I H; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Fritz, James S; Haddad, Paul R

    2003-05-16

    In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression. PMID:12830884

  3. Analysis of energetic materials by ion chromatography

    SciTech Connect

    Hershey, M.K.

    1985-01-01

    Ion chromatography is a rapid, sensitive, and selective method for ion analysis in a variety of matrices. Ion chromatography was used to determine levels on chloride and chlorate in potassium perchlorate. Comparisons were made with the specific ion electrons method presently being used for these analyses. Also to be discussed are ion chromatographic methods for determining ammonium in boron potassium nitrate, and chloride and ammonium in CP.

  4. [Columns and separation mechanism of low pressure ion chromatography].

    PubMed

    Zhang, X; Jiang, X

    1997-01-01

    Ion chromatography which appeared in 1975 has been developed rapidly in recent years. But the working pressure increased with years. In this work, the authors put forward the low pressure ion chromatography (LPIC) and successfully designed several kinds of low pressure ion chromatography with inlet pressure of 1.92 x 10(5)-2.94 x 10(5) Pa. Many cations, such as, alkali metals, NH4+, alkaline earth metals, transition metals, inorganic anions and organic acidic ions can be analyzed rapidly by the technique. The detectable limit of numerous ions reaches 10(-6) g/L. Low working pressure, high performance separation and highly sensitive detection can be realized by LPIC. Among these, the columns play an important part. In this paper, the kinds and species of columns and the analytes are presented. The separation mechanism of low pressure ion chromatography is discussed, which indudes ion exchange equilibrium, complexation equilibrium and ion exclusion reaction. Furthermore, the relation between the exchange capacity of ion exchange media and the concentration of eluent are also discussed. In the meanwhile, the choice of LPIC elution systems and separation conditions are described in this paper too. PMID:15739433

  5. Using Ion Exchange Chromatography to Separate and Quantify Complex Ions

    ERIC Educational Resources Information Center

    Johnson, Brian J.

    2014-01-01

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

  6. Using Ion Exchange Chromatography to Separate and Quantify Complex Ions

    ERIC Educational Resources Information Center

    Johnson, Brian J.

    2014-01-01

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

  7. 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

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

    2011-01-01

    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

  8. A Size Exclusion Chromatography Laboratory with Unknowns for Introductory Students

    ERIC Educational Resources Information Center

    McIntee, Edward J.; Graham, Kate J.; Colosky, Edward C.; Jakubowski, Henry V.

    2015-01-01

    Size exclusion chromatography is an important technique in the separation of biological and polymeric samples by molecular weight. While a number of laboratory experiments have been published that use this technique for the purification of large molecules, this is the first report of an experiment that focuses on purifying an unknown small

  9. A Size Exclusion Chromatography Laboratory with Unknowns for Introductory Students

    ERIC Educational Resources Information Center

    McIntee, Edward J.; Graham, Kate J.; Colosky, Edward C.; Jakubowski, Henry V.

    2015-01-01

    Size exclusion chromatography is an important technique in the separation of biological and polymeric samples by molecular weight. While a number of laboratory experiments have been published that use this technique for the purification of large molecules, this is the first report of an experiment that focuses on purifying an unknown small…

  10. Factors affecting selectivity in ion chromatography.

    PubMed

    Fritz, James S

    2005-08-26

    Methods for separation of ions by ion-exchange, ion-pair, and zwitterion ion chromatography share at least one common thread--the induced formation of a cation-anion pair in the stationary phase. Selectivity can be defined as the relative ability of sample ions to form such a pair. Examples are given in anion-exchange chromatography to show the effect of variations in the geometry, bulkiness and polarity of the resin cation on selectivity. The type of resin matrix, the hydrophobic nature of the resin surface and the degree of solvation also affect chromatographic behavior. The selectivity series observed in ion chromatography seems to be best explained by the interplay of two components: electrostatic attraction (ES) and the enforced-pairing (EP) that is brought about by hydrophobic attraction and by water-enforced ion pairing. Selectivity in ion-pair chromatography (IPC) and in zwitterion ion chromatography (ZIC) is affected by both the mobile phase cation and anion. This leads to elution orders for anions that are different from conventional ion-exchange chromatography (IC) of anions where cations are excluded from the stationary phase and have little effect on a separation. The elution order of anions in ZIC is similar to that in IC except for small anions of 2-charge, which are retained more weakly in ZIC. A unique advantage of ZIC is that sample ions can be eluted as ion pairs with pure water as the eluent and a conductivity detector. The mechanism for separation of anions on a zwitterionic stationary phase has been a subject for considerable debate. The available facts point strongly to a partitioning mechanism or a mixed mechanism in which partitioning is dominant with a weaker ion-exchange component. PMID:16106841

  11. 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 ...

  12. Size-exclusion chromatography system for macromolecular interaction analysis

    DOEpatents

    Stevens, Fred J.

    1988-01-01

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

  13. The History of Ion Chromatography: The Engineering Perspective

    ERIC Educational Resources Information Center

    Evans, Barton

    2004-01-01

    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.

  14. Polymer characterization by size-exclusion chromatography with multiple detection.

    PubMed

    Teresa, M; Laguna, R; Medrano, R; Plana, M P; Tarazona, M P

    2001-06-01

    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 reference polymer, polyphosphazenes which behave abnormally in solution and poly(ethylene oxide) which is soluble in water. Since the relationship between dimensions and molecular mass depends on the extent of interactions between chain segments and solvent molecules, the scaling law provides information about the solution properties of the polymer. PMID:11459299

  15. Chromatography

    MedlinePlus

    Chromatography is a way of separating two or more chemical compounds. Chemical compounds are chemicals that are ... of chemical compound. There are different kinds of chromatography. These include gas, high pressure liquid, or ion ...

  16. Slow-Equilibration Approximation in Kinetic Size Exclusion Chromatography.

    PubMed

    Cherney, Leonid T; Krylov, Sergey N

    2016-04-01

    Kinetic size exclusion chromatography with mass spectrometry detection (KSEC-MS) is a solution-based label-free approach for studying kinetics of reversible binding of a small molecule to a protein. Extraction of kinetic data from KSEC-MS chromatograms is greatly complicated by the lack of separation between the protein and protein-small molecule complex. As a result, a sophisticated time-consuming numerical approach was used for the determination of rate constants in the proof-of-principle works on KSEC-MS. Here, we suggest the first non-numerical (analytical) approach for finding rate constants of protein-small molecule interaction from KSEC-MS data. The approach is based on the slow-equilibration approximation, which is applicable to KSEC-MS chromatograms that reveal two peaks. The analysis of errors shows that the slow-equilibration approximation guarantees that the errors in the rate constants are below 20% if the ratio between the characteristic separation and equilibration times does not exceed 0.1. The latter condition can typically be satisfied for specific interactions such as receptor-ligand or protein-drug. The suggested analytical solution equips analytical scientists with a simple and fast tool for processing KSEC-MS data. Moreover, a similar approach can be potentially developed for kinetic analysis of protein-small molecule binding by other kinetic-separation methods such as nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM). PMID:26954346

  17. An Empirical Formula From Ion Exchange Chromatography and Colorimetry.

    ERIC Educational Resources Information Center

    Johnson, Steven D.

    1996-01-01

    Presents a detailed procedure for finding an empirical formula from ion exchange chromatography and colorimetry. Introduces students to more varied techniques including volumetric manipulation, titration, ion-exchange, preparation of a calibration curve, and the use of colorimetry. (JRH)

  18. Evaluation of size-exclusion chromatography and size-exclusion electrochromatography calibration curves.

    PubMed

    Heyden, Y Vander; Popovici, S T; Schoenmaker, P J

    2002-05-31

    Size-exclusion chromatography (SEC) and size-exclusion electrochromatography (SEEC) are chromatographic techniques used to determine molecular mass (weight) distributions (MWD) of polymers. One important step in the data treatment to derive MWD parameters is the modelling of the calibration curves. The calibration curves applied in SEC and SEEC are generally not linear. In this study the modelling of calibration curves is being examined. Different polynomial models have been evaluated and compared, not only for model fit but also for their predictive properties. It was found that sometimes a straight line and sometimes a third-order polynomial model were best. The best model across the effective range (also called linear range) is not always found to be a straight line. The SEEC curves were found to have considerably higher prediction errors than the SEC ones. Reduction of the number of calibration standards to five or six did not greatly affect the predictive properties of the calibration curves, neither in SEC nor in SEEC. PMID:12113337

  19. Ion Chromatography Analysis of Dibutyl Phosphoric Acid

    SciTech Connect

    Ray, R.J.

    1998-12-04

    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.

  20. Specific determination of selenoaminoacids in whole milk by 2D size-exclusion-ion-paring reversed phase high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP MS).

    PubMed

    Bierla, Katarzyna; Szpunar, Joanna; Lobinski, Ryszard

    2008-08-29

    A procedure was developed for the quantitative recovery of selenomethionine (SeMet) and selenocysteine (SeCys) from whole milk. It was based on the protein unfolding, carbamidomethylation of the aminoacid residues using iodoacetamide and proteolysis using Protease XIV. The selenoaminoacids were specifically determined by ion-paring reversed phase HPLC-ICP MS after their isolation from the post-reaction mixture by size-exclusion LC. Se(IV) present in the sample was derivatized as well and was determined along with the selenoaminoacids. The origin and identity of species were identified by the co-elution with the Se(IV), isotopically labelled selenomethionine, and with the synthetic standard of carbamidomethylated selenocysteine. The method development for SeCys was assisted by using glutathione peroxidase as the SeCys standard. SeMet, SeCys and Se(IV) were quantified by the method of standard additions. The mass balance provided a measure of the method validation. The method was applied to monitoring selenium speciation during supplementation of cows (dose-effect study) with Se-rich yeast containing feed and during milk processing. PMID:18706325

  1. Discovery and early development of non-suppressed ion chromatography.

    PubMed

    Fritz, James S; Gjerde, Douglas T

    2010-08-01

    This year marks the 30th anniversary of the publication of Non-Suppressed Ion Chromatography, which is a method for the rapid separation of anions with on-line conductimetric detection. In this method, the separation column is connected directly to the conductimetric detector. This single-column method is a simpler technique than the original suppressed ion chromatography method, which requires a large suppressor column to reduce the background conductance. In the new method, the background signal is reduced to a manageable level simply by using an ion-exchange separation column of low exchange capacity that lowers the eluent concentration needed for separation. The eluent ion used for separation is chosen based on having large, bulky structure, which lowers the equivalent conductance and facilitates detection of the sample anions. This is a personal account of the initial discovery and early development of non-suppressed ion chromatography. The circumstances for the discovery are recounted by the two authors. Methods are described for determination of anions, cations with indirect detection, and techniques for increasing detection sensitivity. A fundamental equation for the prediction of ion chromatography detector response is given, and the development of several types of detection schemes for ion chromatography is discussed. Finally, the impact of non-suppressed ion chromatography is discussed together with comments on the discovery process. PMID:20819275

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

    ERIC Educational Resources Information Center

    Foster, N.; And Others

    1985-01-01

    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)

  3. Discrimination of rubber-based pressure sensitive adhesives by size exclusion chromatography.

    PubMed

    Kumooka, Yoshio

    2007-08-24

    In this report, three pairs of rubber-based pressure sensitive adhesives were analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), attenuated total reflectance Fourier transform infrared spectrometry (ATR/FT-IR) and size exclusion chromatography (SEC). The size exclusion chromatograph was equipped with a refractive index (RI) detector and an ultraviolet (UV) absorption detector set to measure at 254 nm. Both adhesives of each pair revealed indistinguishable pyrograms and IR spectra, however, the SEC chromatograms were able to provide further discrimination. The differences were observed in the range below the polystyrene equivalent molecular weight of 700 Da. PMID:17052877

  4. Degradation of Ultra-High Molar Mass Polymers in Size-Exclusion Chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The degradation of high molar mass polymers during size-exclusion chromatography (SEC) analysis has been a topic of interest for several decades. Should a polymer degrade during analysis, the accuracy of the molar mass (M) and architectural information obtained will be compromised. To this effect,...

  5. Using ion exchange chromatography to purify a recombinantly expressed protein.

    PubMed

    Duong-Ly, Krisna C; Gabelli, Sandra B

    2014-01-01

    Ion exchange chromatography (IEX) separates molecules by their surface charge, a property that can vary vastly between different proteins. There are two types of IEX, cation exhange and anion exchange chromatography. The protocol that follows was designed by the authors for anion exchange chromatography of a recombinantly expressed protein having a pI of 4.9 and containing two cysteine residues and one tryptophan residue, using an FPLC system. Prior to anion exchange, the protein had been salted out using ammonium sulfate precipitation and partially purified via hydrophobic interaction chromatography (see Salting out of proteins using ammonium sulfate precipitation and Use and Application of Hydrophobic Interaction Chromatography for Protein Purification). Slight modifications to this protocol may be made to accommodate both the protein of interest and the availability of equipment. PMID:24674065

  6. Practical experience with on-line ion chromatography

    SciTech Connect

    Lynch, G.J.

    1991-12-31

    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.

  7. Mineral Separation in a CELSS by Ion-exchange Chromatography

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  8. Automated Precursor Ion Exclusion During LC-MS/MS Data Acquisition for Optimal Ion Identification

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongqi

    2012-08-01

    Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is widely used for characterizing multiple samples of complex mixtures with similar compositions. This article addresses a data acquisition strategy for collecting a maximal number of unique, high-quality MS/MS during LC-MS/MS analysis of multiple samples. Based on the concept that a component only needs to be identified once when analyzing multiple samples with similar compositions, an automated intersample data-dependent acquisition strategy was developed. The strategy is based on precursor ion exclusion (PIE) and is implemented in MassAnalyzer in an automated fashion for Thermo Scientific (San Jose, CA, USA) mass spectrometers. In this method, MassAnalyzer submits one sample at a time to the sample queue. After data acquisition of each sample, MassAnalyzer automatically analyzes the data to generate a PIE list based on the MS/MS precursor ions, merges this list with the list generated from previous runs, adds the list to the MS method file, and submits the next sample to the queue. The PIE list contains both m/z value and time window for each precursor ion, and is generated intelligently so that if an MS/MS is insufficient for identifying the peak of interest, it will be collected again near the top of the peak in the next run. Therefore, the strategy maximizes both quality and the number of unique MS/MS. When automated PIE was used to acquire LC-MS/MS data of an antibody tryptic digest and a soy hydrolysate sample, the number of identified ions increased by 52 % and 93 %, respectively, compared with data acquired without using PIE.

  9. CHEMICAL ANALYSIS OF WET SCRUBBERS UTILIZING ION CHROMATOGRAPHY

    EPA Science Inventory

    The report describes the key elements required to develop a sampling and analysis program for a wet scrubber using ion chromatography as the main analytical technique. The first part of the report describes a sampling program for two different types of wet scrubbers: the venturi/...

  10. ANALYSIS OF FERRIC AND FERROUS IONS IN SOIL EXTRACTS BY ION CHROMATOGRAPHY

    EPA Science Inventory

    A method using ion chromatography (IC) for the analysis of ferrous (Fe 2+) and ferric (Fe 3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic...

  11. Determination of chloride in geological samples by ion chromatography

    USGS Publications Warehouse

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

    1983-01-01

    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.

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

    PubMed

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

    2014-03-14

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

  13. Size-exclusion chromatography-from high-performance to ultra-performance.

    PubMed

    Uliyanchenko, Elena

    2014-10-01

    Size-exclusion chromatography (SEC) enables measurement of the average molecular weights and molecular-weight distributions of polymers. Because these characteristics may, in turn, be correlated with important performance characteristics of plastics, SEC is an essential analytical technique for characterization of macromolecules. Although SEC is one of the oldest instrumental chromatographic techniques, it is still under continuous development, as a result of the great demand for increased resolution and faster analysis in SEC. Ultra-high-pressure size-exclusion chromatography (UHPSEC) was recently introduced to satisfy the growing demands of analytical chemists. Using instrumentation capable of generating very high pressures and columns packed with small particles, this technique enables greater separation efficiency and faster analysis than are achieved with conventional SEC. UHPSEC is especially advantageous for high-resolution analysis of oligomers, for very rapid polymer separations, and as a second dimension in comprehensive two-dimensional liquid chromatography of polymers. In this paper we discuss the benefits of UHPSEC for separation of macromolecules, with examples from the literature. PMID:25116601

  14. Ion exclusion by sub-2-nm carbon nanotube pores.

    PubMed

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

    2008-11-11

    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. PMID:18539773

  15. Ion exclusion by sub-2-nm carbon nanotube pores

    PubMed Central

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

    2008-01-01

    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. PMID:18539773

  16. Size-exclusion chromatography for the determination of the boiling point distribution of high-boiling petroleum fractions.

    PubMed

    Boczkaj, Grzegorz; Przyjazny, Andrzej; Kamiński, Marian

    2015-03-01

    The paper describes a new procedure for the determination of boiling point distribution of high-boiling petroleum fractions using size-exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size-exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size-exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high-boiling mixtures, for which a standard high-temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high-performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high-molar-mass aromatic compounds, and thus increases the sensitivity of final boiling point determination. PMID:25545251

  17. Characterization of synthetic dyes by comprehensive two-dimensional liquid chromatography combining ion-exchange chromatography and fast ion-pair reversed-phase chromatography.

    PubMed

    Pirok, Bob W J; Knip, Jitske; van Bommel, Maarten R; Schoenmakers, Peter J

    2016-03-01

    In the late 19th century, newly invented synthetic dyes rapidly replaced the natural dyes on the market. The characterization of mixtures of these so-called early synthetic dyes is complicated through the occurrence of many impurities and degradation products. Conventional one-dimensional liquid chromatography does not suffice to obtain fingerprints with sufficient resolution and baseline integrity. Comprehensive two-dimensional liquid chromatography (LC×LC) is employed in this study, with ion-exchange chromatography in the first dimension and fast ion-pair liquid chromatography in the second. Retention in the first dimension is largely determined by the number of charges, while the selection of a small ion-pair reagent (tetramethylammonium hydroxide) in the second dimension causes retention to be largely determined by the molecular structure of the dye. As a result, there is a high degree of orthogonality of the two dimensions, similar to the values typically encountered in GC×GC. The proposed LC×LC method shows a theroretical peak capacity of about 2000 in an analysis time of about three hours. Clear, informative fingerprints are obtained that open a way to a more efficient characterization of dyes used in objects of cultural heritage. PMID:26868445

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

    SciTech Connect

    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

    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.

  19. Detergent screening of the human voltage-gated proton channel using fluorescence-detection size-exclusion chromatography

    PubMed Central

    Agharkar, Amruta; Rzadkowolski, Jennifer; McBroom, Mandy; Gonzales, Eric B

    2014-01-01

    The human voltage-gated proton channel (Hv1) is a membrane protein consisting of four transmembrane domains and intracellular amino- and carboxy-termini. The protein is activated by membrane depolarization, similar to other voltage-sensitive proteins. However, the Hv1 proton channel lacks a traditional ion pore. The human Hv1 proton channel has been implicated in mediating sperm capacitance, stroke, and most recently as a biomarker/mediator of cancer metastasis. Recently, the three-dimensional structures for homologues of this voltage-gated proton channel were reported. However, it is not clear what artificial environment is needed to facilitate the isolation and purification of the human Hv1 proton channel for structural study. In the present study, we generated a chimeric protein that placed an enhanced green fluorescent protein (EGFP) to the amino-terminus of the human Hv1 proton channel (termed EGFP-Hv1). The chimeric protein was expressed in a baculovirus expression system using Sf9 cells and subjected to detergent screening using fluorescence-detection size-exclusion chromatography. The EGFP-Hv1 proton channel can be solubilized in the zwitterionic detergent Anzergent 3–12 and the nonionic n-dodecyl-β-d-maltoside (DDM) with little protein aggregation and a prominent monomeric protein peak at 48 h postinfection. Furthermore, we demonstrate that the chimeric protein exhibits a monomeric protein peak, which is distinguishable from protein aggregates, at the final size-exclusion chromatography purification step. Taken together, we can conclude that solubilization in DDM will provide a useable final product for further structural characterization of the full-length human Hv1 proton channel. PMID:24863684

  20. Liquid Chromatography in 1982.

    ERIC Educational Resources Information Center

    Freeman, David H.

    1982-01-01

    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)

  1. Ion chromatography in the manufacture of multilayer circuit boards

    NASA Astrophysics Data System (ADS)

    Smith, Robert E.

    1990-09-01

    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 2-D liquid chromatography also are described. Chemically suppressed conductivity and photometric detection are used.

  2. Ion chromatography in the manufacture of multilayer circuit boards

    SciTech Connect

    Smith, R.E.

    1990-09-01

    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.

  3. Determination of selected anions in water by ion chromatography

    USGS Publications Warehouse

    Fishman, Marvin J.; Pyen, Grace

    1979-01-01

    Ion chromatography is a rapid, sensitive, precise, and accurate method for the determination of major anions in 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).

  4. Ion chromatography in the manufacture of multilayer circuit boards

    NASA Astrophysics Data System (ADS)

    Smith, Robert E.

    1990-01-01

    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.

  5. Size exclusion chromatography for the removal of pigments from extracellular ligninolytic enzyme extracts from decayed wheat straw.

    PubMed

    Shukla, Dharmendra; Patel, Bhavesh; Modi, Hasmukh; Vyas, Bharat Rajiv Manuel

    2011-11-01

    Solid-state fermentation of wheat straw was carried out by a native white rot basidiomycete Daedaleopsis flavida strain 5A. Extract prepared from the 12-day decayed wheat straw contained extracellular ligninolytic enzymes like manganese peroxidase (MnP), manganese-independent peroxidase (MIP), lignin peroxidase (LiP) and laccase along with straw-degraded products and pigments. Sephacryl S-200 size exclusion chromatography in 16/100 column was used for the separation of these ligninolytic enzymes and straw-degraded products and pigments. Recovery of pigment-free ligninolytic enzyme activities as protein was 40% of the total proteins loaded and specific LiP activity increased 34 fold after size exclusion chromatography. Thus accurate estimation of LiP by veratryl alcohol oxidation assay was possible only after the removal of interfering pigments. The reproducibility of size exclusion chromatography is adjudged satisfactory from the consistent results obtained after seven repetitive uses of matrices. PMID:22471206

  6. Quantifying vitamin K-dependent holoprotein compaction caused by differential γ-carboxylation using high-pressure size exclusion chromatography.

    PubMed

    Vanderslice, Nicholas C; Messer, Amanda S; Vadivel, Kanagasabai; Bajaj, S Paul; Phillips, Martin; Fatemi, Mostafa; Xu, Weijie; Velander, William H

    2015-06-15

    This study uses high-pressure size exclusion chromatography (HPSEC) to quantify divalent metal ion (X(2+))-induced compaction found in vitamin K-dependent (VKD) proteins. Multiple X(2+) binding sites formed by the presence of up to 12 γ-carboxyglutamic acid (Gla) residues are present in plasma-derived FIX (pd-FIX) and recombinant FIX (r-FIX). Analytical ultracentrifugation (AUC) was used to calibrate the Stokes radius (R) measured by HPSEC. A compaction of pd-FIX caused by the filling of Ca(2+) and Mg(2+) binding sites resulted in a 5 to 6% decrease in radius of hydration as observed by HPSEC. The filling of Ca(2+) sites resulted in greater compaction than for Mg(2+) alone where this effect was additive or greater when both ions were present at physiological levels. Less X(2+)-induced compaction was observed in r-FIX with lower Gla content populations, which enabled the separation of biologically active r-FIX species from inactive ones by HPSEC. HPSEC was sensitive to R changes of approximately 0.01nm that enabled the detection of FIX compaction that was likely cooperative in nature between lower avidity X(2+) sites of the Gla domain and higher avidity X(2+) sites of the epidermal growth factor 1 (EGF1)-like domain. PMID:25804408

  7. Antioxidant activity of whey protein fractions isolated by gel exclusion chromatography and protease treatment.

    PubMed

    Bayram, Tuğba; Pekmez, Murat; Arda, Nazli; Yalçin, A Süha

    2008-05-15

    Whey proteins were isolated from whey powder by a combination of gel exclusion chromatography and protease (pepsin or trypsin) treatment. Whey solution (6g/dl) was applied to Sephadex G-200 column chromatography and three fractions were obtained. Gel electrophoresis (SDS-PAGE) was used to identify the fractions; the first one contained immunoglobulins and bovine serum albumin, the second contained beta-lactoglobulin and alpha-lactalbumin whereas the third fraction contained small peptides. We have also subjected the whey filtrate to proteases (pepsin and trypsin). Treatment with proteases showed that beta-lactoglobulin can be obtained after hydrolysis of the second fraction with pepsin. When the whey filtrate was treated with pepsin and then applied to Sephadex G-200 column chromatography three fractions were obtained; the first one was bovine serum albumin, the second was beta-lactoglobulin and the third fraction contained small peptides. After trypsin treatment only two fractions were obtained; the first one was serum albumin and the second fraction was an alpha-lactalbumin rich fraction. We have determined the antioxidant activity of the fractions using an assay based on the measurement of superoxide radical scavenging activity. Our results showed that among the three fractions, the first fraction had the highest superoxide radical scavenging activity. Also, protease treatment of the second fraction resulted in an increase in the antioxidant activity. PMID:18585135

  8. Ion chromatography detection of fluoride in calcium carbonate.

    PubMed

    Lefler, Jamie E; Ivey, Michelle M

    2011-09-01

    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 3σ limit of detection is 0.2 mg of fluoride/kg of calcium carbonate. PMID:21859530

  9. On-column refolding of corticotropin-releasing factor receptor 1 extracellular domain by size exclusion chromatography.

    PubMed

    Ersoy, Maria; Matic, Sandra; Schmidt, Stefan R

    2009-10-01

    Expressing the extracellular domain of corticotropin releasing factor receptor 1 in Escherichia coli usually results in the formation of inclusion bodies. Here we describe the optimization of refolding by applying size exclusion chromatography with a denaturing guanidine hydrochloride gradient and a refolding buffer containing glycerol. Several chromatographic parameters like gradient length, flow rate, sample concentration and chromatography resin characteristics were evaluated. Recovery yields of refolded protein above 50% using a Superdex 200 column demonstrate the usefulness of this method. PMID:19404927

  10. Protein Nitrogen Determination by Kjeldahl Digestion and Ion Chromatography.

    PubMed

    Wang, Hsiaoling; Pampati, Nagarani; McCormick, William M; Bhattacharyya, Lokesh

    2016-06-01

    We report development and validation of a simple, rapid, and accurate method for the quantitation of protein nitrogen, which combines Kjeldahl digestion and ion chromatography with suppressed conductivity detection and requires nanomolar amount of nitrogen in samples (≥10 μg protein). The mechanism of suppressed conductivity detection does not permit analysis of samples containing copper (present in Kjeldahl digestion solution) and aluminum (present in many vaccines as adjuvants) due to precipitation of their hydroxides within the suppressor. We overcame this problem by including 10 μM oxalic acid in Kjeldahl digests and in the eluent (30 mM methanesulfonic acid). The chromatography is performed using an IonPac CS-16 cation exchange column by isocratic elution. The method reduces the digestion time to less than 1 h and eliminates the distillation and titration steps of the Kjeldahl method, thereby reducing the analysis time significantly and improving precision and accuracy. To determine protein nitrogen in samples containing non-protein nitrogen, proteins are precipitated by a mixture of deoxycholate and trichloroacetic acid and the precipitates are analyzed after dissolving in KOH. The method is particularly useful for biological samples that are limited and can also be applied to food, environmental, and other materials. PMID:27238484

  11. Exclusive diffractive processes in electron-ion collisions

    NASA Astrophysics Data System (ADS)

    Toll, Tobias; Ullrich, Thomas

    2013-02-01

    We present a new technique to calculate the cross section for diffractive vector meson production and deeply virtual Compton scattering (DVCS) in electron-ion collisions based on the dipole model. The measurement of these processes can provide valuable information on nonlinear QCD phenomena, such as gluon saturation, and is the the only known way to gain insight into the spatial distribution of gluons in nuclei. We present predictions of differential cross-section distribution dσ/dQ2 and dσ/dt for J/ψ and ϕ meson production for diffractive processes of heavy nuclei, and demonstrate the feasibility of extracting the gluon source distribution of heavy nuclei, F(b), from coherent diffraction. We briefly introduce a new event generator based on our method that can be used for studying exclusive diffractive processes at a future electron-ion collider.

  12. Chromatography.

    ERIC Educational Resources Information Center

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

    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)

  13. 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

    Fortier, N.E.

    1988-07-01

    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.

  14. Measurement of osmotic second virial coefficients by zonal size-exclusion chromatography.

    PubMed

    Winzor, Donald J

    2016-07-01

    Numerical simulation of protein migration reflecting linear concentration dependence of the partition isotherm has been used to invalidate a published procedure for measuring osmotic second virial coefficients (B22) by zonal exclusion chromatography. Failure of the zonal procedure to emulate its frontal chromatographic counterpart reflects ambiguity about the solute concentration that should be used to replace the applied concentration in the rigorous quantitative expression for frontal migration; the recommended use of the peak concentration in the eluted zone is incorrect on theoretical grounds. Furthermore, the claim for its validation on empirical grounds has been traced to the use of inappropriate B22 magnitudes as the standards against which the experimentally derived values were being tested. PMID:27095059

  15. Fluorescence-Detectino Size-Exclusion Chromatography for Precrystallization Screening of Integral Membrane Proteins

    SciTech Connect

    Kawate,T.; Gouaux, E.

    2006-01-01

    Formation of well-ordered crystals of membrane proteins is a bottleneck for structure determination by X-ray crystallography. Nevertheless, one can increase the probability of successful crystallization by precrystallization screening, a process by which one analyzes the monodispersity and stability of the protein-detergent complex. Traditionally, this has required microgram to milligram quantities of purified protein and a concomitant investment of time and resources. Here, we describe a rapid and efficient precrystallization screening strategy in which the target protein is covalently fused to green fluorescent protein (GFP) and the resulting unpurified protein is analyzed by fluorescence-detection size-exclusion chromatography (FSEC). This strategy requires only nanogram quantities of unpurified protein and allows one to evaluate localization and expression level, the degree of monodispersity, and the approximate molecular mass. We show the application of this precrystallization screening to four membrane proteins derived from prokaryotic or eukaryotic organisms.

  16. One-step cleanup for PAH residue analysis in plant matrices using size-exclusion chromatography.

    TOXLINE Toxicology Bibliographic Information

    Hubert A; Popp P; Wenzel KD; Engewald W; Schüürmann G

    2003-05-01

    A new one-step cleanup procedure, based on size-exclusion chromatography (SEC), usable for the extracts from accelerated solvent extraction (ASE), Soxhlet extraction, or ultrasonic extraction (USE), is described. The method is suitable for the determination of polycyclic aromatic hydrocarbons (PAHs), especially from very complicated plant matrices (e.g. pine needles, deciduous leaves, mosses). The main improvement compared with previous conventional procedures is that analyte peaks barely overlap with matrix peaks in the chromatograms and that it is a very rapid and simple one-step procedure with clearly improved analytical performance. Essential advantages of this SEC procedure are the sharper GC-MS chromatograms for the PAH fraction at retention times between 9.2 and 12.0 min, distinctly separated substance peaks resulting in better analysis, shorter running times, and lower solvent consumption.

  17. Size-Exclusion Chromatography for the Analysis of Protein Biotherapeutics and their Aggregates

    PubMed Central

    Hong, Paula; Koza, Stephan; Bouvier, Edouard S. P.

    2012-01-01

    In recent years, the use and number of biotherapeutics has increased significantly. For these largely protein-based therapies, the quantitation of aggregates is of particular concern given their potential effect on efficacy and immunogenicity. This need has renewed interest in size-exclusion chromatography (SEC). In the following review we will outline the history and background of SEC for the analysis of proteins. We will also discuss the instrumentation for these analyses, including the use of different types of detectors. Method development for protein analysis by SEC will also be outlined, including the effect of mobile phase and column parameters (column length, pore size). We will also review some of the applications of this mode of separation that are of particular importance to protein biopharmaceutical development and highlight some considerations in their implementation. PMID:23378719

  18. Size exclusion chromatography of synthetic polymers and biopolymers on common reversed phase and hydrophilic interaction chromatography columns.

    PubMed

    Caltabiano, Anna M; Foley, Joe P; Barth, Howard G

    2016-03-11

    This work describes the applicability of common reversed phase and HILIC columns for size exclusion chromatography of synthetic and natural polymers. Depending on the nature of the solute and column stationary phase, a "non-retention" condition must be created with the aid of the mobile phase to achieve a unique size-based separation in isocratic mode. The various bonded phases show remarkable differences in size separations that are controlled by mobile phase conditions. Polymer-mobile phase and column-mobile phase solvation interactions determine polymer hydrodynamic volume (or solute bulkiness) and polymer-column steric interaction. Solvation interactions in turn depend on polymer, mobile phase and stationary phase polarities. Column-mobile phase solvation interactions determine the structural order of the bonded ligands that can vary from ordered (extended, aligned away from the silica substrate) to disordered (folded, pointing toward the silica substrate). Chain order increases with increased solvent penetration into the bonded phase. Increased chain order reduces pore volume, and therefore decreases the size-separation efficiency of a column. Conversely, decreased chain order increases pore volume and therefore increases the size-separation efficiency. The thermodynamic quality of the mobile phase also plays a significant role in the separation of polymers. "Poor" solvents can significantly reduce the hydrodynamic diameter of a solute and thus change their retention behavior. Medium polarity stationary phases, such as fluoro-phenyl and cyano, exhibit a unique retention behavior. With an appropriate polarity mobile phase, polar and non-polar synthetic polymers of the same molecular masses can be eluted at the same retention volumes. PMID:26877177

  19. What can in situ ion chromatography offer for Mars exploration?

    PubMed

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

    2014-07-01

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

  20. Consequences of on-line dialysis on polyelectrolyte molar masses determined by size-exclusion chromatography with light scattering detection.

    PubMed

    Radke, Wolfgang

    2016-02-01

    Size-exclusion chromatography with light scattering detection experiments conducted on poly(acrylic acid) neutralized to different degrees or using hydroxides with different counterions suggest that the same counterion and degree of neutralization is observed at the detector, irrespective of salt concentration, degree of neutralization and counterion at the time of injection. This strongly supports that during the chromatographic experiment the counterions of the polyelectrolyte are exchanged with those of the eluent, resulting in an effective dialysis of the polyelectrolyte solution during the size-exclusion chromatography experiment. Consequently, the refractive index increment determined by a refractive index detector equals the refractive index increment obtained after excessive dialysis against the pure eluent. Therefore, the species detected and characterized by light scattering coupled to size-exclusion chromatography are not identical to the species injected into the chromatographic system. Despite this structural change during the chromatographic experiments, the correct molar mass for the injected species is obtained by size-exclusion chromatography with light scattering detection. PMID:26606911

  1. Metal ion binding to phospholipid bilayers evaluated by microaffinity chromatography.

    PubMed

    Ross, Eric E; Hoag, Christian; Pfeifer, Zach; Lundeen, Christopher; Owens, Sarah

    2016-06-17

    Group I and II ion binding to phospholipid membranes was evaluated by affinity chromatography utilizing a new stationary phase system based on lipid bilayers supported within large-pore particles composed of Stöber silica spheres. Using an inductively coupled plasma mass spectrometer for detection, robust determination of binding selectivity within group II ions is achieved with capillary columns containing nanomole quantities of lipid and using picomoles of metal analyte. Columns with a unique lipid formulation can be prepared within three hours using a solvent-casting assembly method. The observable thermotropic phase behavior of dipalmitoylphosphatidylcholine has a significant effect on alkaline metal binding and demonstrates the dynamic nature of the supported bilayers. Of the group I ions, only lithium exhibits retention with neutral phosphatidylcholine bilayer stationary phases. A comparison of Stöber-based supports with two commercially available large-pore silicas reveals the effect that particle structure has on analyte accessibility to the bilayer surface as evaluated by retention per supported lipid mass. PMID:27189434

  2. Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography

    SciTech Connect

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

    2010-06-15

    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.

  3. Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography

    SciTech Connect

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

    2010-06-15

    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.

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

    PubMed

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

    2013-02-01

    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

  5. Oscillatory transverse electric field enhances protein resolution and capacity of size-exclusion chromatography.

    PubMed

    Tan, Guo-Min; Dong, Xiao-Yan; Sun, Yan

    2006-03-01

    Protein separations by a novel size-exclusion electrochromatography (SEEC) are presented. The present SEEC, denoted as pSEEC, was established with an oscillatory low-voltage electric field perpendicular to the mobile-phase streamline. Retention experiments with different proteins indicated that the influence of electric field strength on the partition coefficient is different for different proteins as well as for the same protein under different mobile-phase conditions. These results of protein retention led to the experimental design of protein separations with binary mixtures of BSA and immunoglobulin G (IgG), myoglobin (Myo) and lysozyme (Lys), as well as ovalbumin (Oval) and Myo. The separation results for the binary protein systems sufficiently exhibited the applicability of the pSEEC for various separations in terms of their molecular weights (MWs) as well as pIs. For example, it was possible to separate the gel-excluded proteins (BSA/IgG) as well as gel-permeable and similar-molecular-weight proteins (Myo/Lys) by the pSEEC. Moreover, in the cases of Oval/ Myo, which could be partially separated by size-exclusion chromatography, the use of the pSEEC greatly improved the resolution and the separation became possible at high sample loading. The results indicate that the pSEEC technology is promising for preparative protein separations. PMID:16605088

  6. Determination of polydextrose in foods by ion chromatography: collaborative study.

    PubMed

    Craig, S A; Holden, J F; Khaled, M Y

    2001-01-01

    Eight collaborating laboratories assayed 7 blind duplicate pairs of foods for polydextrose content. The 7 test sample pairs ranged from low (2%) to high (95%) levels. The following foods were prepared with polydextrose mixed into the other ingredients and then baked, cooked, or otherwise prepared: milk chocolate candy, iced tea, sugar cookie, grape jelly, soft jellied candy, and powdered drink mix. Collaborators received a polydextrose standard to develop a calibration curve. The method determined polydextrose by ion chromatography, after removal of interfering food components (high molecular weight solubles). Repeatability standard deviations (RSDr) ranged from 3.93 to 9.04%; reproducibility standard deviations (RSDR) ranged from 4.48 to 14.06%. The average recovery was 94%. PMID:11324613

  7. Determination of heparin on intraocular lens surfaces by ion chromatography.

    PubMed

    Ander, B; Karlsson, A; Ohrlund, A

    2001-05-11

    A sensitive and selective method has been developed for the determination of heparin on heparin coated PMMA, poly(methyl methacrylate), intraocular lenses. Heparin was hydrolysed to glucosamine and glucuronic acid, and the content of glucosamine was determined using ion chromatography with pulsed amperometric detection. In order to verify that a complete hydrolysis was obtained for the heparin on the coated intraocular lenses, electron spectroscopy for chemical analysis (ESCA) was used for analysing traces of sulphur on the lens surfaces. The sensitivity of the method allows quantitative determination of 150 ng of heparin on one individual lens. The new method was compared to a standard spectrophotometric method, measuring the colour intensity of a heparin toluidine blue complex. Correlation between the methods was shown for samples prepared from PMMA lenses coated with different amounts of heparin. PMID:11403462

  8. Separation of glyceride positional isomers by silver ion chromatography.

    PubMed

    Févrie, P; Bine, A; Dufossé, L; Grée, R; Yvergnaux, F

    2001-07-20

    Separation of triglyceride and diglyceride positional isomers by silver ion high-performance liquid chromatography coupled with an evaporative light-scattering detector is described. The triglyceride isomers had a fatty acid composition of CLC and CCL, where C and L were caprylic acid and linoleic acid, respectively. Diglyceride isomers, 1,2(2,3)-diglyceride and 1,3-diglyceride, which contained caprylic acid were separated too. A solvent system based on n-hexane, 2-propanol, ethyl acetate, and acetonitrile with a flow-rate of 0.8 ml/min was developed. Calibration curves of CLC and CCL were achieved with triolein as internal standard. Using this method, the incorporation of linoleic acid onto specific a position of glycerol backbone can be monitored. PMID:11510559

  9. Derivatization patterns among starch chain populations assessed by ion-exchange chromatography: a model system approach.

    PubMed

    Hong, Jung Sun; Huber, Kerry C

    2015-05-20

    Reaction patterns of wheat starch derivatized with a fluorescent probe (model reaction system) were investigated over the course of a reaction period (0.5, 4, 12, or 24h). Debranched derivatives were fractionated into three populations (Unbound, Bound-1, Bound-2) based on charge density via anion-exchange chromatography, with each ion-exchanged fraction further analyzed by size-exclusion chromatography (refractive index [RI] and fluorescence [FL] detection) to assess proportions and patterns of reaction on amylose (AM) and amylopectin (AP) long (LC), medium (MC), and short (SC) branch chains. Approximately 11-12% of the total chains accounted for 63-75% of the FL recovered in the two bound fractions. FL peaks representing AM, AP-LC, AP-MC, AP-SC, and intermediate material (eluted with AM based on molecular size, but reacted more akin to AP-LC) were monitored over the reaction period. Fractionation behaviors varied amongst starch chains, attributable to the impact of the granule structure on molecular reaction patterns. PMID:25817689

  10. Ion Exclusion by Sub 2-nm Carbon Nanotube Pores

    SciTech Connect

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

    2008-04-09

    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.

  11. Enhanced methodology for porting ion chromatography retention data.

    PubMed

    Park, Soo Hyun; Shellie, Robert A; Dicinoski, Greg W; Schuster, Georg; Talebi, Mohammad; Haddad, Paul R; Szucs, Roman; Dolan, John W; Pohl, Christopher A

    2016-03-01

    Porting is a powerful methodology to recalibrate an existing database of ion chromatography (IC) retention times by reflecting the changes of column behavior resulting from either batch-to-batch variability in the production of the column or the manufacture of new versions of a column. This approach has been employed to update extensive databases of retention data of inorganic and organic anions forming part of the "Virtual Column" software marketed by Thermo Fisher Scientific, which is the only available commercial optimization tool for IC separation. The current porting process is accomplished by performing three isocratic separations with two representative analyte ions in order to derive a porting equation which expresses the relationship between old and new data. Although the accuracy of retention prediction is generally enhanced on new columns, errors were observed on some columns. In this work, the porting methodology was modified in order to address this issue, where the porting equation is now derived by using six representative analyte ions (chloride, bromide, iodide, perchlorate, sulfate, and thiosulfate). Additionally, the updated porting methodology has been applied on three Thermo Fisher Scientific columns (AS20, AS19, and AS11HC). The proposed approach showed that the new porting methodology can provide more accurate and robust retention prediction on a wide range of columns, where average errors in retention times for ten test anions under three eluent conditions were less than 1.5%. Moreover, the retention prediction using this new approach provided an acceptable level of accuracy on a used column exhibiting changes in ion-exchange capacity. PMID:26860051

  12. Developments in suppressor technology for inorganic ion analysis by ion chromatography using conductivity detection.

    PubMed

    Hadda, Paul R; Jackson, Peter E; Shaw, Matthew J

    2003-06-01

    A review is presented detailing the development and use of suppression devices for the conductimetric detection of inorganic ions by ion chromatography (IC). An overview of the general response equation for conductivity detection is also given. Topics of discussion include the role and function of suppressors, the development of early suppressors including packed column and membrane devices from 1975 to 1990 and the subsequent progression towards present day commercially available suppressors and recent innovations. Post-suppression devices for signal enhancement are also discussed. PMID:12877197

  13. Electrodialytic membrane suppressors for ion chromatography make programmable buffer generators.

    PubMed

    Chen, Yongjing; Srinivasan, Kannan; Dasgupta, Purnendu K

    2012-01-01

    The use of buffer solutions is immensely important in a great variety of disciplines. The generation of continuous pH gradients in flow systems plays an important role in the chromatographic separation of proteins, high-throughput pK(a) determinations, etc. We demonstrate here that electrodialytic membrane suppressors used in ion chromatography can be used to generate buffers. The generated pH, computed from first principles, agrees well with measured values. We demonstrate the generation of phosphate and citrate buffers using a cation-exchange membrane (CEM) -based anion suppressor and Tris and ethylenediamine buffers using an anion-exchange membrane (AEM) -based cation suppressor. Using a mixture of phosphate, citrate, and borate as the buffering ions and using a CEM suppressor, we demonstrate the generation of a highly reproducible (avg RSD 0.20%, n = 3), temporally linear (pH 3.0-11.9, r(2) > 0.9996), electrically controlled pH gradient. With butylamine and a large concentration (0.5 M) of added NaCl, we demonstrate a similar linear pH gradient of large range with a near-constant ionic strength. We believe that this approach will be of value for the generation of eluents in the separation of proteins and other biomolecules and in online process titrations. PMID:22103670

  14. Assessing natural organic matter treatability using high performance size exclusion chromatography.

    PubMed

    Chow, Christopher W K; Fabris, Rolando; Van Leeuwen, John; Wang, Dongsheng; Drikast, Mary

    2008-09-01

    This paper reports the use of high performance size exclusion chromatography (HPSEC) as a tool to assess NOM removal by coagulation. Quantitative information such as percentage removal can be determined after "peak-fitting" the HPSEC molecular weight profile of the source water. A peak-fitting approach was developed based on the molecular weight profile of dissolved organic matter from surface water. A sequential jar testing procedure with five treatment steps was used to characterize organics and to confirm that several NOM components were recalcitrant to coagulation with alum. Despite differences found in both the concentration and character of NOM in three surface waters studied, the final concentrations and characteristics (e.g., molecular weight profile) were very similar after five treatment stages. The molecular weight profiles of the recalcitrant organics were subsequently used to build a peak-fitting technique for NOM removal. The approach was validated by further jar test results of several other water sources, such as ground and river waters, including one found to be very difficult to treat in terms of NOM removal by alum treatment. Predictions of removable and nonremovable organic fractions by coagulation using this peak fitting technique were found to be within 10% of actual values. PMID:18800549

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

    PubMed

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

    2012-09-21

    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

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

    SciTech Connect

    Branthaver, J.F.; Duvall, J.J.; Petersen, J.C. )

    1990-07-01

    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.

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

    PubMed Central

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

    2010-01-01

    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. PMID:20680668

  18. Characterization of major radical scavenger species in bovine milk through size exclusion chromatography and functional assays.

    PubMed

    Clausen, Morten R; Skibsted, Leif H; Stagsted, Jan

    2009-04-01

    Radical scavenging activities of bovine milk components were quantified following size exclusion chromatography (SEC) with postcolumn characterization of fractions using the scavenging of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radicals (ABTS*(+)) in the Trolox equivalent antioxidant capacity (TEAC) assay and peroxyl radicals formed from cleavage of 2,2'-azobis(2-amidinopropane) (AAPH) in the oxygen radical absorbance capacity (ORAC) fluorometric assay. Caseins were quantitatively the major radical scavenger species in both assays, whereas beta-lactoglobulin (beta-lg) and alpha-lactalbumin (alpha-la) were much less active and only in the peroxyl radical assay. The radical scavenging activity of the caseins could be quantitatively accounted for by their constituent amino acids, as there were no effects of denaturing agents or complete digestion with proteases. In contrast, the activities of the whey proteins were dependent on denaturation or partial hydrolysis and dominated by the free thiol in beta-lg. A component in milk serum with a molecular mass of approximately 100 kDa contributed significantly to both ABTS*(+) and peroxyl radical scavenging but was absent in whey. This radical scavenger was identified as beta-casein. The only significant low molecular weight radical scavenger species were identified as ascorbate and urate in both assays. PMID:19281275

  19. Size exclusion chromatography for analyses of fibroin in silk: optimization of sampling and separation conditions

    NASA Astrophysics Data System (ADS)

    Pawcenis, Dominika; Koperska, Monika A.; Milczarek, Jakub M.; Łojewski, Tomasz; Łojewska, Joanna

    2014-02-01

    A direct goal of this paper was to improve the methods of sample preparation and separation for analyses of fibroin polypeptide with the use of size exclusion chromatography (SEC). The motivation for the study arises from our interest in natural polymers included in historic textile and paper artifacts, and is a logical response to the urgent need for developing rationale-based methods for materials conservation. The first step is to develop a reliable analytical tool which would give insight into fibroin structure and its changes caused by both natural and artificial ageing. To investigate the influence of preparation conditions, two sets of artificially aged samples were prepared (with and without NaCl in sample solution) and measured by the means of SEC with multi angle laser light scattering detector. It was shown that dialysis of fibroin dissolved in LiBr solution allows removal of the salt which destroys stacks chromatographic columns and prevents reproducible analyses. Salt rich (NaCl) water solutions of fibroin improved the quality of chromatograms.

  20. Contactless conductivity detection of synthetic polymers in non-aqueous size-exclusion electrokinetic chromatography.

    PubMed

    Oudhoff, Kathalijne A; Macka, Miroslav; Haddad, Paul R; Schoenmakers, Peter J; Kok, Wim Th

    2005-03-11

    A capacitively coupled contactless conductivity detection (CCD) system has been applied for the detection of neutral synthetic polymers in capillary size-exclusion electrokinetic chromatography (SEEC). Polystyrene standards, that were used as a model compounds, were separated on a capillary column packed with porous 10 microm silica particles with an electrokinetically driven mobile phase, and detected by CCD and UV detection simultaneously. Mass-calibration curves for polystyrene were constructed. Satisfactory results were obtained for the linearity, the run-to-run repeatability (<0.2% for the relative retention and <4% for the peak area) and the robustness of the detector. One of the major issues in this preliminary study was to investigate the origin of the peaks observed for the polystyrene standards. The effect of the molar mass of the polystyrenes on the sensitivity was small. Therefore, the signals obtained could not be explained as the result of an increased viscosity and a decreased solution conductivity of the solute zone. An alternative hypothesis is suggested, and recommendations for further research are given. PMID:15844557

  1. Comments on exclusion of polymer chains from small pores and its relation to gel permeation chromatography.

    PubMed

    Casassa, E F

    1976-01-01

    Some criticisms of our theoretical treatment of the partial exclusion of flexible-chain polymers in solution from cavities of macromolecular size and its application to gel permeation chromatography are examined. In other discussion, it is confirmed by simple reasoning that the identification, explicit or implicit in various studies, of the mean projection of a polymer molecule onto a line as a characteristic dimension governing the extent of permeation of simple pores does not depend on specific molecular models. Our previous calculation of permeation by certain random-flight branched-chain species is shown to lead, incidentally, to the mean projection for these structures. From relations between the mean projection and the hydrodynamic volume of a molecule, it appears that the product of intrinsic viscosity and molecular weight is not a common calibration factor for elution of all molecular species from a gel chromatographic column, but theory and experience do support the validity of this correlation among solutes with similar molecular architecture. PMID:1249988

  2. Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography.

    PubMed

    Huang, Huiping; Chow, Christopher W K; Jin, Bo

    2016-04-01

    Understanding the complexity of dissolved organic matter (DOM) in stormwater has drawn a lot of interest, since DOM from stormwater causes not only environmental impacts, but also worsens downstream aquatic quality associated with water supply and treatability. This study introduced and employed high-performance size exclusion chromatography (HPSEC) coupled with an ultraviolet-visible (UV-vis) diode array detector to assess changes in stormwater-associated DOM characteristics. Stormwater DOM was also analysed in relation to storm event characteristics, water quality and spectroscopic analysis. Statistical tools were used to determine the correlations within DOM and water quality measurements. Results showed that dissolved organic carbon (DOC) and UV absorbance at 254nm (UV254) as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events studied. Both detector wavelengths (210 and 254nm) and their ratio (A210/A254) were found to provide additional information on the physiochemical properties of stormwater-associated DOM. This study indicated that A210/A254 is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon species. This study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters, and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences. PMID:27090716

  3. Analysis of reduced monoclonal antibodies using size exclusion chromatography coupled with mass spectrometry

    NASA Astrophysics Data System (ADS)

    Liu, Hongcheng; Gaza-Bulseco, Georgeen; Chumsae, Chris

    2009-12-01

    Size-exclusion chromatography (SEC) has been widely used to detect antibody aggregates, monomer, and fragments. SEC coupled to mass spectrometry has been reported to measure the molecular weights of antibody; antibody conjugates, and antibody light chain and heavy chain. In this study, separation of antibody light chain and heavy chain by SEC and direct coupling to a mass spectrometer was further studied. It was determined that employing mobile phases containing acetonitrile, trifluoroacetic acid, and formic acid allowed the separation of antibody light chain and heavy chain after reduction by SEC. In addition, this mobile phase allowed the coupling of SEC to a mass spectrometer to obtain a direct molecular weight measurement. The application of the SEC-MS method was demonstrated by the separation of the light chain and the heavy chain of multiple recombinant monoclonal antibodies. In addition, separation of a thioether linked light chain and heavy chain from the free light chain and the free heavy chain of a recombinant monoclonal antibody after reduction was also achieved. This optimized method provided a separation of antibody light chain and heavy chain based on size and allowed a direct measurement of molecular weights by mass spectrometry. In addition, this method may help to identify peaks eluting from SEC column directly.

  4. Rapid characterization of biotherapeutic proteins by size-exclusion chromatography coupled to native mass spectrometry.

    PubMed

    Haberger, Markus; Leiss, Michael; Heidenreich, Anna-Katharina; Pester, Oxana; Hafenmair, Georg; Hook, Michaela; Bonnington, Lea; Wegele, Harald; Haindl, Markus; Reusch, Dietmar; Bulau, Patrick

    2016-01-01

    High-molecular weight aggregates such as antibody dimers and other side products derived from incorrect light or heavy chain association typically represent critical product-related impurities for bispecific antibody formats. In this study, an approach employing ultra-pressure liquid chromatography size-exclusion separation combined with native electrospray ionization mass spectrometry for the simultaneous formation, identification and quantification of size variants in recombinant antibodies was developed. Samples exposed to storage and elevated temperature(s) enabled the identification of various bispecific antibody size variants. This test system hence allowed us to study the variants formed during formulation and bio-process development, and can thus be transferred to quality control units for routine in-process control and release analytics. In addition, native SEC-UV/MS not only facilitates the detailed analysis of low-abundant and non-covalent size variants during process characterization/validation studies, but is also essential for the SEC-UV method validation prior to admission to the market. PMID:26655595

  5. Analysis of anions in beer using ion chromatography

    PubMed Central

    Bruce, Jonathan

    2002-01-01

    The majority of anions found in beer are a consequence of impurities derived from the water used during the brewing process. The process of beer manufacture consists of malting, brewing and fermentation followed by maturation before filtration and finally storage. Strict quality control is required because the presence of certain anions outside strictly defined tolerance limits can affect the flavour characteristics of the finished product. The anions present were quantified using the technique of ion chromatography with the Metrohm modular system following sample preparation. The analysis produced a result of the order 200 mg l-1 for chloride, phosphate and sulphate and around 20 mg l-1 for nitrate. If the chloride level exceeds 250 mg l-1, then the sweetness of the beer is enhanced, but yeast flocculation can be hindered. An excess of sulphate can give a sharp, dry edge to hopped beers and excessive amounts of nitrate have been found to harm the yeast metabolism after conversion to the nitrite form. As water is a primary ingredient within beer, its quality and type is a fundamental factor in establishing many of the distinctive regional beers that can be found in the United Kingdom and is thus monitored carefully. PMID:18924733

  6. Online comprehensive two-dimensional ion chromatography × capillary electrophoresis.

    PubMed

    Ranjbar, Leila; Gaudry, Adam J; Breadmore, Michael C; Shellie, Robert A

    2015-09-01

    A comprehensively coupled online two-dimensional ion chromatography-capillary electrophoresis (IC × CE) system for quantitative analysis of inorganic anions and organic acids in water is introduced. The system employs an in-house built sequential injection-capillary electrophoresis instrument and a nonfocusing modulation interface comprising a tee-piece and a six-port two-position injection valve that allows comprehensive sampling of the IC effluent. High field strength (+2 kV/cm) enables rapid second-dimension separations in which each peak eluted from the first-dimension separation column is analyzed at least three times in the second dimension. The IC × CE approach has been successfully used to resolve a suite of haloacetic acids, dalapon, and common inorganic anions. Two-dimensional peak capacity for IC × CE was 498 with a peak production rate of 9 peaks/min. Linear calibration curves were obtained for all analytes from 5 to 225 ng/mL (except dibromoacetic acid (10-225 ng/mL) and tribromoacetic acid (25-225 ng/mL)). The developed approach was used to analyze a spiked tap water sample, with good measured recoveries (69-119%). PMID:26171657

  7. Ion-exchange chromatography for the characterization of biopharmaceuticals.

    PubMed

    Fekete, Szabolcs; Beck, Alain; Veuthey, Jean-Luc; Guillarme, Davy

    2015-09-10

    Ion-exchange chromatography (IEX) is a historical technique widely used for the detailed characterization of therapeutic proteins and can be considered as a reference and powerful technique for the qualitative and quantitative evaluation of charge heterogeneity. The goal of this review is to provide an overview of theoretical and practical aspects of modern IEX applied for the characterization of therapeutic proteins including monoclonal antibodies (Mabs) and antibody drug conjugates (ADCs). The section on method development describes how to select a suitable stationary phase chemistry and dimensions, the mobile phase conditions (pH, nature and concentration of salt), as well as the temperature and flow rate, considering proteins isoelectric point (pI). In addition, both salt-gradient and pH-gradient approaches were critically reviewed and benefits as well as limitations of these two strategies were provided. Finally, several applications, mostly from pharmaceutical industries, illustrate the potential of IEX for the characterization of charge variants of various types of biopharmaceutical products. PMID:25800161

  8. Fluoride and aluminum release from restorative materials using ion chromatography

    PubMed Central

    OKTE, Zeynep; BAYRAK, Sule; FIDANCI, Ulvi Reha; SEL, Tevhide

    2012-01-01

    Objective The aim of this study was to determine the amounts of fluoride and aluminum released from different restorative materials stored in artificial saliva and double-distilled water. Material and Methods Cylindrical specimens (10 x 1 mm) were prepared from 4 different restorative materials (Kavitan Plus, Vitremer, Dyract Extra, and Surefil). For each material, 20 specimens were prepared, 10 of which were stored in 5 mL artificial saliva and 10 of which were stored in 5 mL of double-distilled water. Concentrations of fluoride and aluminum in the solutions were measured using ion chromatography. Measurements were taken daily for one week and then weekly for two additional weeks. Data were analyzed using two-way ANOVA and Duncan's multiple range tests (p<0.05). Results The highest amounts of both fluoride and aluminum were released by the resin-modified glass ionomer cement Vitremer in double-distilled water (p<0.05). All materials released significantly more fluoride in double-distilled water than in artificial saliva (p<0.05). In artificial saliva, none of the materials were observed to release aluminum. Conclusion It was concluded that storage media and method of analysis should be taken into account when the fluoride and aluminum release from dental materials is assessed. PMID:22437674

  9. Determination of cyanogenic compounds in edible plants by ion chromatography.

    PubMed

    Cho, Hye-Jeon; Do, Byung-Kyung; Shim, Soon-Mi; Kwon, Hoonjeong; Lee, Dong-Ha; Nah, Ahn-Hee; Choi, Youn-Ju; Lee, Sook-Yeon

    2013-06-01

    Cyanogenic glycosides are HCN-producing phytotoxins; HCN is a powerful and a rapidly acting poison. It is not difficult to find plants containing these compounds in the food supply and/or in medicinal herb collections. The objective of this study was to investigate the distribution of total cyanide in nine genera (Dolichos, Ginkgo, Hordeum, Linum, Phaseolus, Prunus, Phyllostachys, Phytolacca, and Portulaca) of edible plants and the effect of the processing on cyanide concentration. Total cyanide content was measured by ion chromatography following acid hydrolysis and distillation. Kernels of Prunus genus are used medicinally, but they possess the highest level of total cyanide of up to 2259.81 CN(-)/g dry weight. Trace amounts of cyanogenic compounds were detected in foodstuffs such as mungbeans and bamboo shoots. Currently, except for the WHO guideline for cassava, there is no global standard for the allowed amount of cyanogenic compounds in foodstuffs. However, our data emphasize the need for the guidelines if plants containing cyanogenic glycosidesare to be developed as dietary supplements. PMID:24278641

  10. Evaluating the impact of different exogenous factors on silk textiles deterioration with use of size exclusion chromatography

    NASA Astrophysics Data System (ADS)

    Pawcenis, Dominika; Smoleń, Mariusz; Aksamit-Koperska, Monika A.; Łojewski, Tomasz; Łojewska, Joanna

    2016-06-01

    Size exclusion chromatography (SEC), especially coupled with multiple angle laser light scattering detector (MALLS) is a powerful tool in diagnostics of deterioration of historic and art objects to evaluate their condition. In this paper, SEC-UV-MALLS-DRI technique was applied to study degradation of silk fibroin samples ( Bombyx mori) artificially aged under various conditions: in the presence of oxygen, in different amount of water vapour and in volatile organic products (VOCs), all at temperature of 90 °C. Conditions were chosen in such a way that it mimicked real conditions of textiles' storing during exhibitions and in show cases. The influence of temperature, moisture and VOCs content on the state of silk textiles was examined with the use of size exclusion chromatography. Pseudo-zero-order Ekenstam equation was applied to study degradation rates of fibroin with use of the approximated values of DP of fibroin.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  12. Ion chromatography for determination of metabolic patterns of sulfate-reducing bacteria

    SciTech Connect

    Lebel, A.; Yen, T.F.

    1984-04-01

    Ion exchange chromatography is used to monitor the concentration of ionic species in bacterial growth media. The ions of interest are sulfate, lactate, acetate, and carbonate. All of these ions play important roles in the metabolism of the desired bacteria. It is possible, using this monitoring technique, to explore the growth of sulfate-reducing bacteria of the Desulfovibrio genus.

  13. 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

    Fortier, N.E.

    1988-01-01

    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.

  14. Unraveling the mystery of natural rubber biosythesis part I: investigation of the composition and growth of in vitro natural rubber using high resolution size exclusion chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Monitoring the growth of in vitro natural rubberwas accomplished by high resolution size exclusion chromatography, SEC.Washed rubber particles isolated from H. brasiliensis latex, containing the rubber transferase enzyme, were used to catalyze the polymerization of synthetic isopentenyl pyrophosphat...

  15. A broad-standard technique for correcting for band broadening in size-exclusion chromatography.

    PubMed

    Zhang, Peng; Mazoyer, Paul; Gilbert, Robert G

    2016-04-22

    Band broadening in size-exclusion chromatography (SEC) is always present to some extent. Broadening effects on averages such as the weight- and number average molecular weights (MW¯ and Mn¯ respectively) are minimal with modern SEC systems. However, broadening distorts the shape of the true molecular weight distribution (MWD), which causes problems if one wants to compare the detailed form of the MWD to a model. An addition to current methods for overcoming this problem is presented. One starts with a sufficiently wide range of samples whose exact values of Mn¯ andMW¯ have been measured by non-SEC methods (e.g. by fluorimetry and light scattering, respectively, of the sample without size separation). A true (unbroadened) molecular weight distribution for a sample can be obtained by deconvolution (here using a maximum-entropy algorithm) by fitting SEC data for these samples to these exact Mn¯ and MW¯ values to find the values of the parameters in a sufficiently flexible assumed broadening function. This was modelled using simulated band broadening and subsequent deconvolution, with the broadening parameters least-squares fitted to the "exact" sets of values of Mn¯ and MW¯. The results show that if these Mn¯ and MW¯ values are for a series of broad (not narrow) standards covering a sufficient range of molecular weight, then after deconvolution, a good representation of the original molecular weight distribution used in the simulation is obtained. The method should prove useful for water-soluble polymers, for which it is often difficult to obtain narrow standards of a wide range of molecular weight, as required in a number of well-established methods for correcting for band broadening. PMID:27016112

  16. Size-exclusion chromatography-based enrichment of extracellular vesicles from urine samples

    PubMed Central

    Lozano-Ramos, Inés; Bancu, Ioana; Oliveira-Tercero, Anna; Armengol, María Pilar; Menezes-Neto, Armando; Del Portillo, Hernando A.; Lauzurica-Valdemoros, Ricardo; Borràs, Francesc E.

    2015-01-01

    Renal biopsy is the gold-standard procedure to diagnose most of renal pathologies. However, this invasive method is of limited repeatability and often describes an irreversible renal damage. Urine is an easily accessible fluid and urinary extracellular vesicles (EVs) may be ideal to describe new biomarkers associated with renal pathologies. Several methods to enrich EVs have been described. Most of them contain a mixture of proteins, lipoproteins and cell debris that may be masking relevant biomarkers. Here, we evaluated size-exclusion chromatography (SEC) as a suitable method to isolate urinary EVs. Following a conventional centrifugation to eliminate cell debris and apoptotic bodies, urine samples were concentrated using ultrafiltration and loaded on a SEC column. Collected fractions were analysed by protein content and flow cytometry to determine the presence of tetraspanin markers (CD63 and CD9). The highest tetraspanin content was routinely detected in fractions well before the bulk of proteins eluted. These tetraspanin-peak fractions were analysed by cryo-electron microscopy (cryo-EM) and nanoparticle tracking analysis revealing the presence of EVs. When analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis, tetraspanin-peak fractions from urine concentrated samples contained multiple bands but the main urine proteins (such as Tamm–Horsfall protein) were absent. Furthermore, a preliminary proteomic study of these fractions revealed the presence of EV-related proteins, suggesting their enrichment in concentrated samples. In addition, RNA profiling also showed the presence of vesicular small RNA species. To summarize, our results demonstrated that concentrated urine followed by SEC is a suitable option to isolate EVs with low presence of soluble contaminants. This methodology could permit more accurate analyses of EV-related biomarkers when further characterized by -omics technologies compared with other approaches. PMID:26025625

  17. High-throughput characterization of virus-like particles by interlaced size-exclusion chromatography.

    PubMed

    Ladd Effio, Christopher; Oelmeier, Stefan A; Hubbuch, Jürgen

    2016-03-01

    The development and manufacturing of safe and effective vaccines relies essentially on the availability of robust and precise analytical techniques. Virus-like particles (VLPs) have emerged as an important and valuable class of vaccines for the containment of infectious diseases. VLPs are produced by recombinant protein expression followed by purification procedures to minimize the levels of process- and product-related impurities. The control of these impurities is necessary during process development and manufacturing. Especially monitoring of the VLP size distribution is important for the characterization of the final vaccine product. Currently used methods require long analysis times and tailor-made assays. In this work, we present a size-exclusion ultra-high performance liquid chromatography (SE-UHPLC) method to characterize VLPs and quantify aggregates within 3.1min per sample applying interlaced injections. Four analytical SEC columns were evaluated for the analysis of human B19 parvo-VLPs and murine polyoma-VLPs. The optimized method was successfully used for the characterization of five recombinant protein-based VLPs including human papillomavirus (HPV) VLPs, human enterovirus 71 (EV71) VLPs, and chimeric hepatitis B core antigen (HBcAg) VLPs pointing out the generic applicability of the assay. Measurements were supported by transmission electron microscopy and dynamic light scattering. It was demonstrated that the iSE-UHPLC method provides a rapid, precise and robust tool for the characterization of VLPs. Two case studies on purification tools for VLP aggregates and storage conditions of HPV VLPs highlight the relevance of the analytical method for high-throughput process development and process monitoring of virus-like particles. PMID:26845741

  18. Analysis of low-molecular-mass inorganic and organic anions by ion chromatography-atmospheric pressure ionization mass spectrometry.

    PubMed

    Ahrer, W; Buchberger, W

    1999-08-27

    Different nonvolatile mobile phases have been tested for the combination of ion-exchange chromatography combined with mass spectrometric detection of anions and organic acids. Buffer systems based on carbonate, sulfate, oxalate and citrate as the eluting species have been used. Among these, citrate proved to be the most versatile eluent allowing the separation of anions with absolute detection limits between 0.4 and 0.7 ng and of organic acids with detection limits between 0.4 and 4 ng in the non-suppressed mode. In the suppressed eluent mode iodate, bromate and chlorate could be separated using sodium carbonate as the mobile phase resulting in detection limits of 50 pg. The method was applied to the analysis of water samples containing oxyhalides originating from ozonization. Additionally, organic acids were separated by chromatographic separation techniques like reversed-phase, ion-pair or ion-exclusion chromatography and the compatibility with mass spectrometry was investigated with special respect to sensitivity of this detection mode. PMID:10497946

  19. Speciation of trace elements in proteins in human and bovine serum by size exclusion chromatography and inductively coupled plasma-mass spectrometry with a magnetic sector mass spectrometer.

    PubMed

    Wang, J; Houk, R S; Dreessen, D; Wiederin, D R

    1999-10-01

    Proteins are separated by size exclusion chromatography while atomic ions from the inorganic elements are detected on-line by inductively coupled plasma-mass spectrometry. A double focusing mass analyzer provides very high sensitivity, low background, and sufficient spectral resolution to separate the atomic ions of interest from most polyatomic ions at the same nominal m/z value. The chromatograms show the distribution of the elements of interest between protein-bound and free fractions and provide the approximate molecular weights of those protein fractions that contain the elements monitored. The distribution of various elements, including V, Mo, Fe, Co, Mn, and lanthanides, in human or bovine serum samples are shown. Alkali metals and Tl are present primarily as free metal ions and are not bound to proteins. Inorganic elements spiked into the serum samples can be followed into various proteins. EDTA does not remove Fe, Pb, Sn, or Th from the proteins but does extract Mn from some proteins. Procedures for determining the effects of breaking disulfide linkages on the metal binding characteristics of proteins are also described. PMID:10550683

  20. Separation of catecholamines and their metabolites by adsorption, ion-pair and soap chromatography.

    PubMed

    Knox, J H; Jurand, J

    1976-09-29

    The separation of catecholamines and their metabolites has been carried out by high-performance liquid chromatography using three systems: liquid-solid adsorption, ion-pair partition, and soap chromatography. In the last newly developed technique a reversed-phase packing is used in conjunction with an aqueous organic eluent containing a detergent. The detergent is chosen so that its ion can form ion-pairs with ions of the solutes. Soap chromatography proved the best technique in terms of column efficiency (giving 3000-5000 plates in 125 mm), resolution and sensitivity of detection. Noradrenaline, adrenaline and dopamine, their 3-O-methyl derivatives, L-3,4-dihydroxyphenylalanine, homovanillic acid and other related compounds could be separated in less than 10 min at the 10-50-ng level on columns whose plate heights were in the range of 20-40 mum. The dependence of retention on the concentration of organic modifier and on detergent concentration for three anionic detergents is reported. The method is applied to the direct analysis of urine and the potential of the method for such analyses, especially of pathological urines is demonstrated. Soap chromatography is likely to enlarge the scope of application of high-performance liquid chromatography to biochemical analysis. It is a powerful method for the separation of ionizable compounds which could replace conventional ion-exchange chromatography. PMID:977684

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  2. Toxicity evaluation of organic sediment extracts resolved by size exclusion chromatography using rainbow trout hepatocytes.

    PubMed

    Gagn, F; Pardos, M; Blaise, C; Turcotte, P; Qumerais, B; Fouquet, A

    1999-10-01

    The (geno)toxicity of sediment dichloromethane extracts and fractions obtained by size exclusion chromatography were evaluated to investigate effects based on size fractionation. In this study, three sediments were selected according to their incremental contamination in PAHs and in PCBs: Hamilton harbour, Toronto bay and lake St. Clair sediments. Heavy metals, total sulfur and elemental sulfur (S8) were also determined in the (un)fractionated sediment extracts. The liver cells were exposed to concentrations of sediment extracts and fractionated samples for 24 h at 15 degrees C, afterwhich cell viability, cytochrome P4501A1 activity, available free Zn, DNA damage and oxidative stress were determined. The results showed that the sediment extracts contained high levels of sulfur most of which was found in the low molecular weight (LMW) region, i.e., the 2000-50 atomic mass unit (amu) fraction. Elemental sulfur (S8) accounted for 14-41% of extractable sulfur and were found to elute in the post-column volume (PCV) fraction despite its molecular weight of 256 amu. Heavy metals were found mainly in the HMW (i.e. the > 2000 amu) fraction and LMW fractions and very few or none were observed in the PCV fractions. In sediment extracts, sublethal effects were present principally by the HMW and LMW fractions suggesting that some chemicals were also associated with high molecular weight compounds of extractable organic matter. Less toxicity or effect was sometimes found in the extract indicating an antagonistic effect of the contaminants. We found that cell viability and genotoxicity evaluations could be performed on the unfractionated extracts while EROD, available Zn and oxidative stress measurements should be performed on the LMW fractions because of possible antagonist or shielding effects. Considering the cytotoxic responses, the best toxicity ranking in respect to contaminant levels in sediment extract was obtained with the LMW and PCV fractions which accounted for most of the toxic responses in the chromatographic fractions. Moreover, the shielding effect could be explained, in part, by the association of LMW contaminants to large macromolecules. PMID:10481253

  3. Characterization and quantification of humic substances 2D-Fluorescence by usage of extended size exclusion chromatography.

    PubMed

    Wagner, Martin; Schmidt, Wido; Imhof, Lutz; Grübel, Anika; Jähn, Camilla; Georgi, Denise; Petzoldt, Heike

    2016-04-15

    In this article, two methods for in-depth analysis of humic substances fluorescence are presented. The first one allows the combined analysis of fluorescence excitation-emission matrix (EEM) with chromatography technique. The main issue is the coupling of size exclusion chromatography (SEC) with spectroscopy by the use of an absorption and a fluorescence spectrometer as additional detectors. These allow a detailed characterization of humic substances depending on their molecular size, concentration and optical properties. For the evaluation of the resulting complex data, a model based on non-negative matrix factorization, which is also presented in this article, was developed. From the results of the examined humic substances standards, the second method was developed. It allows the characterization and quantification of humic substances fluorescence of a natural water sample solely on the basis of an excitation-emission matrix. The validation of the model is carried out within the framework of extensive analysis of real water samples. PMID:26900971

  4. Impact of extraction and elution media on non-size effects in size exclusion chromatography of proteins.

    PubMed

    Lambrecht, Marlies A; Rombouts, Ine; Van Kelst, Lotte; Delcour, Jan A

    2015-10-01

    Size exclusion chromatography is extensively used to separate proteins and to determine their apparent molecular weights. It separates proteins based on hydrodynamic volume, but interactions between the chromatography resin and proteins lead to non-size effects. This report discusses the impact of co-solvents [salt, urea, sodium dodecyl sulfate (SDS), dithiothreitol] in extraction media when separating wheat gluten proteins, soy glycinin, bovine serum albumin and ovalbumin on a Biosep-SEC-S4000 column. With acetonitrile/water (1:1, v/v) containing 0.05% (v/v) trifluoroacetic acid as eluent, salts and SDS in the extraction media increase while urea decreases non-size effects. Most gluten and globular proteins are extractable in sodium phosphate buffer (0.050M; pH 6.8) containing 2.0% (w/v) SDS. This chromatographic medium allows analyzing mixtures of various proteins without any non-size effects. PMID:26365913

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

    SciTech Connect

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

    1987-12-01

    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.

  6. Variable-temperature size exclusion chromatography for the study of the structural changes in g-quadruplex.

    PubMed

    Benabou, Sanae; Eritja, Ramon; Gargallo, Raimundo

    2013-01-01

    The conformational equilibria of a guanine-rich sequence found at the promoter region of the human c-kit oncogene are studied by means of circular dichroism spectroscopy (CD) and variable-temperature size exclusion chromatography (SEC). It is shown that the wild sequence ckit21 exists as a mixture of monomeric and multimeric G-quadruplexes. Appropriate mutation of several bases in the wild sequence produces the shift from parallel to antiparallel G-quadruplex, as well as the disappearance of multimeric species. The shift from the antiparallel to the parallel conformation induced by temperature is reflected in both CD and SEC profiles. PMID:25937962

  7. Study of ion exclusion using artificial reference samples for rocks

    SciTech Connect

    Valkiainen, M.; Aalto, H.; Lehikoinen, J.; Olin, M.

    1999-07-01

    Matrix diffusion in rocks has been extensively studied experimentally with various methods including tracer experiments. Comparing the rock-capacity factors ({alpha}) for Cl-36 to corresponding values for H-3, an anion-exclusion tendency has been observed in many cases. This study uses a well-characterized reference material: porous silica (Geltech Inc.), with pore diameters of 2.5, 5, 7.5 and 20 nanometers. The equilibration-leaching method and tracers H-3 (H-3) and Cl-36 (Cl{sup {minus}}) were used to determine the capacity factors of the samples in three molarities of NaCl solution: 0.0026, 0.01 and 0.1 mol/liter. The ratio {alpha}{sub Cl}/{alpha}{sub H-3} gives the anion exclusion for each solution/pore diameter combination. A clear anion-exclusion tendency was seen both as a function of the decreasing pore diameter and liquid molarity. The modeling was based on the assumption that the silica surface acts as a proton donor according to SiOH = SiO{sup {minus}} + H{sup +}. The pore dimensions are also included in the calculations. In the case of the silica samples, good agreement was found when comparing the experimental and calculated values of chloride exclusion. This suggests that the surface complexation model for matrix diffusion can explain the observed exclusion phenomena in rocks although the parameters needed for the application of the model are difficult to obtain in the case of rocks.

  8. Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

    NASA Astrophysics Data System (ADS)

    Karicheva, E.; Guseva, N.; Kambalina, M.

    2016-03-01

    Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

  9. Application of ion chromatography to the study of hydrolysis of some halogenated hydrocarbons at ambient temperatures

    NASA Technical Reports Server (NTRS)

    Otterson, D. A.

    1978-01-01

    The application of ion chromatography to the study of very slow rates of hydrolysis of some halogenated hydrocarbons was investigated. The halide concentrations in the aqueous phase of mixtures of a carbonate buffer (pH = 10.3) and either chloroform (CHC13) or fluorotrichloromethane (CFC13) after aging for various lengths of time at room temperature, were determined by ion chromatography. Hydrolysis of CHC13 caused the C1(-) concentration to increase by about 1500 ppb per day. On the other hand neither the F(-) or C1(-) concentration in the CFC13 mixture increased by as much as 1 ppb per day. The magnitude of errors in the determination of halides prevented any firm conclusions regarding hydrolysis in this mixture. However, these results were used to show how ion chromatography could expedite identification of the hydrolyzing substance as well as investigations of hydrolysis mechanisms.

  10. Combined Yamamoto approach for simultaneous estimation of adsorption isotherm and kinetic parameters in ion-exchange chromatography.

    PubMed

    Rüdt, Matthias; Gillet, Florian; Heege, Stefanie; Hitzler, Julian; Kalbfuss, Bernd; Guélat, Bertrand

    2015-09-25

    Application of model-based design is appealing to support the development of protein chromatography in the biopharmaceutical industry. However, the required efforts for parameter estimation are frequently perceived as time-consuming and expensive. In order to speed-up this work, a new parameter estimation approach for modelling ion-exchange chromatography in linear conditions was developed. It aims at reducing the time and protein demand for the model calibration. The method combines the estimation of kinetic and thermodynamic parameters based on the simultaneous variation of the gradient slope and the residence time in a set of five linear gradient elutions. The parameters are estimated from a Yamamoto plot and a gradient-adjusted Van Deemter plot. The combined approach increases the information extracted per experiment compared to the individual methods. As a proof of concept, the combined approach was successfully applied for a monoclonal antibody on a cation-exchanger and for a Fc-fusion protein on an anion-exchange resin. The individual parameter estimations for the mAb confirmed that the new approach maintained the accuracy of the usual Yamamoto and Van Deemter plots. In the second case, offline size-exclusion chromatography was performed in order to estimate the thermodynamic parameters of an impurity (high molecular weight species) simultaneously with the main product. Finally, the parameters obtained from the combined approach were used in a lumped kinetic model to simulate the chromatography runs. The simulated chromatograms obtained for a wide range of gradient lengths and residence times showed only small deviations compared to the experimental data. PMID:26306913

  11. High resolution separation of recombinant monoclonal antibodies by size-exclusion ultra-high performance liquid chromatography (SE-UHPLC).

    PubMed

    Yang, Renee; Tang, Yun; Zhang, Bing; Lu, Xuemei; Liu, Alice; Zhang, Yonghua Taylor

    2015-05-10

    Size-exclusion chromatography (SEC) is an important mode of separation used in monoclonal antibody (mAb) characterization and quality control. SEC separates mAbs into three major species: high molecular weight species, main peak (predominantly monomer), and low molecular weight species. However, mAb SEC separations have low resolution between the different sized species, and the analysis is slow with low sample throughput. The introduction of size-exclusion ultra-high performance liquid chromatography (SE-UHPLC) columns offers a new opportunity to improve both the resolution and throughput of SEC analysis. This study demonstrates that SE-UHPLC columns deliver better resolution of size variants in a shorter period of time than conventional SEC columns. For example, an SE-UHPLC column 300-mm in length produced separation of mAb Fab/c fragments in less than 10min, in comparison to a conventional SEC column output, where these fragments co-elute with the main peak. Furthermore, we observed that high back pressure does not generate HMWS under optimized mobile phase conditions for mAbs. The platform SE-UHPLC method has been demonstrated to be suitable for the analysis of multiple mAbs, with greatly improved sample throughput and peak resolution of mAb size variants. PMID:25766848

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

    NASA Astrophysics Data System (ADS)

    Xie, Wenchun

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

  13. Relative Quantification of Sites of Peptide and Protein Modification Using Size Exclusion Chromatography Coupled with Electron Transfer Dissociation

    NASA Astrophysics Data System (ADS)

    Xie, Boer; Sharp, Joshua S.

    2016-04-01

    One difficult problem in the analysis of peptide modifications is quantifying isomeric modifications that differ by the position of the amino acid modified. HPLC separation using C18 reverse phase chromatography coupled with electron transfer dissociation (ETD) in tandem mass spectrometry has recently been shown to be able to relatively quantify how much of a given modification occurs at each amino acid position for isomeric mixtures; however, the resolution of reverse phase chromatography greatly complicates quantification of isomeric modifications by ETD because of the chromatographic separation of peptides with identical modifications at different sequence positions. Using peptide oxidation as a model system, we investigated the use of size exclusion chromatography coupled with ETD fragmentation to separate peptide sequences. This approach allows for the benefits of chromatographic separation of peptide sequences while ensuring co-elution of modification isomers for accurate relative quantification of modifications using standard data-dependent acquisitions. Using this method, the relative amount of modification at each amino acid can be accurately measured from single ETD MS/MS spectra in a standard data-dependent acquisition experiment.

  14. Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

    PubMed

    Huang, Zhongping; Ni, Chengzhu; Zhu, Zhuyi; Pan, Zaifa; Wang, Lili; Zhu, Yan

    2015-05-01

    The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ? 0.9990. The limits of detection were in the range of 0.67 to 1.51 ?g/L, based on the signal-to-noise ratio of 3 and a 25 ?L injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts. PMID:25641739

  15. Ion-exchange sorption and preparative chromatography of biologically active materials

    SciTech Connect

    Samsonov, G.V.

    1986-01-01

    This book presents information on the following topics: the problems of fine physico-chemical biotechnology; types of highly permeable network polyelectrolytes; methods for studying the permeability and porosity of network polyelectrolytes; the conformation state and flexibility of the structural elements of network polyelectrolytes; ion-exchange processes without the sorption of physiologically active substances; ion exchange, hydration, and swelling; nucleosides, nucleotides, alkaloids, sulfonamides, and miscellaneous physiologically active subtances; sharp front formation for the exchange of ions with the same valences; standard quasi-equilibrium frontal chromatography on ionites; sorption kinetics in ionites with structural heterogeneity; experimental investigations of the diffusivities of organic and physiologically active ions in ionite beads; and increasing the efficiency of low-pressure chromatography by using surface-layer and bidispersed ionites.

  16. Novel determination of phytate by ion chromatography in wild rice and diet composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have developed an ion chromatography (IC) assay using ultraviolet (UV) detection following post-column derivatization with ferric nitrate to determine phytate [inositol hexakis phosphate (iP6)] (1) (2) in wild rice samples and other diet composites. Samples were ground to a fine homogeneous powd...

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

    SciTech Connect

    Coleman, C.J.

    2002-12-19

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

  18. 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...

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

    ERIC Educational Resources Information Center

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

    2004-01-01

    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.

  20. Analysis of anions in geological brines using ion chromatography

    SciTech Connect

    Merrill, R.M.

    1985-03-01

    Ion chromatographic procedures for the determination of the anions bromide, sulfate, nitrite, nitrate, phosphate, and iodide in brine samples have been developed and are described. The techniques have been applied to the analysis of natural brines, and geologic evaporites. Sample matrices varied over a range from 15,000 mg/L to 200,000 mg/L total halogens, nearly all of which is chloride. The analyzed anion concentrations ranged from less than 5 mg/L in the cases of nitrite, nitrate, and phosphate, to 20,000 mg/L in the case of sulfate. A technique for suppressing chloride and sulfate ions to facilitate the analysis of lower concentration anions is presented. Analysis times are typically less than 20 minutes for each procedure and the ion chromatographic results compare well with those obtained using more time consuming classical chemical analyses. 10 references, 14 figures.

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

    ERIC Educational Resources Information Center

    Brunauer, Linda S.; Davis, Kathryn K.

    2008-01-01

    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…

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

    ERIC Educational Resources Information Center

    Brunauer, Linda S.; Davis, Kathryn K.

    2008-01-01

    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

  3. Continuous separation of carbohydrates by ion-exchange chromatography

    SciTech Connect

    Wolfgang, J.; Prior, A.; Bart, H.J.; Messenboeck, R.C.; Byers, C.H.

    1997-01-01

    A synthetic mixture of fructose, mannitol and sorbitol was continuously separated by a chromatographic method using a cation-exchange resin (Dowex 50W-X8) in its Ca{sup 2+}-form as the stationary phase. An annular chromatograph (AC) was used to achieve a continuous mode of operation. Distribution and mass transfer coefficients of the three substances as well as bed properties were obtained by batch chromatography. The separation was simulated mathematically in terms of an approximate linear chromatographic theory was applied to the modeling of the behavior of the continuous separations. The influence of rotation rate, column loading, eluent flow rate and feed concentration on the resolution of the individual peaks were investigated.

  4. 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...

  5. Separation of large DNA molecules by size exclusion chromatography-based microchip with on-chip concentration structure

    NASA Astrophysics Data System (ADS)

    Azuma, Naoki; Itoh, Shintaro; Fukuzawa, Kenji; Zhang, Hedong

    2016-06-01

    The separation of DNA molecules according to their size represents a fundamental bioanalytical procedure. Here, we report the development of a chip-sized device, consisting of micrometer-sized fence structures fabricated in a microchannel, for the separation of large DNA molecules (over 10 kbp) based on the principle of size exclusion chromatography (SEC). In order to achieve separation, two approaches were utilized: first, the DNA samples were concentrated immediately prior to separation using nanoslit structures, with the aim of improving the resolution. Second, a theoretical model of SEC-based separation was established and applied in order to predict the optimal voltage range for separation. In this study, we achieved separation of λ DNA (48.5 kbp) and T4 DNA (166 kbp) using the present SEC-based microchip.

  6. Towards determination of absolute molar mass of cellulose polymer by size exclusion chromatography with mulitple angle laser light scattering detection.

    PubMed

    Pawcenis, Dominika; Thomas, Jacob L; Łojewski, Tomasz; Milczarek, Jakub M; Łojewska, Joanna

    2015-08-28

    The study focuses on determination of a set of crucial parameters for molar mass calculation of cellulose from the results of size exclusion chromatography coupled with multiple angle laser light scattering (MALLS) and differential refractive index (DRI) detectors. In the present work, cellulose has been derivatised to obtain cellulose tricarbanilate (CTC) soluble in tetrahydrofuran (THF). The parameters of Rayleigh scattering in the MALLS detector: refractive index increment (dn/dc) and second virial coefficient (A2) of CTC in THF were determined for laser wavelength 658nm. In order to avoid errors resulting from cellulose derivatisation by-products present in the CTC solution, the so called "on-line" method of measuring dn/dc and A2 was applied. Based on the A2 determination, its influence on cellulose molar mass calculations and cellulose molecular dimensions were critically assessed. The latter includes evaluation of artificially aged cellulose towards conceivable branching by conformation plot analysis. PMID:26210115

  7. Preferential solvation of a dicyanate ester monomer and poly(sulfone) in different organic solvents by size-exclusion chromatography.

    PubMed

    Recalde, Ileana B; Porcar, Iolanda; Campos, Agustín; Gómez, Clara M

    2002-01-01

    Preferential solvation parameters A in the ternary systems solvent (1) -monomer (2) -polymer (3) were determined as a tool to measure the compatibility between the cyanate ester monomer Arocy B10 and poly(sulfone), PSF, in the presence of three organic solvents: tetrahydrofuran, dimethylformamide and dicloromethane. The A parameter was measured by size-exclusion chromatography at different monomer-to-polymer ratios. The quantitative evaluation was rigorously made at polymer-diluted conditions. PSF was found to be preferentially solvated by the monomer. Concerning the solvent used, systems containing tetrahydrofuran showed the strongest solvation, the lowest A values being those obtained in dicloromethane. These results were in accordance with the intrinsic viscosity values of the PSF-solvent systems. The variation of A values with the Arocy B10 concentration is strongly dependent upon the nature of the solvent. PMID:11822397

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

    PubMed

    Wang, Zhengxin; Marcus, R Kenneth

    2014-07-18

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

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

    PubMed

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

    2012-12-28

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

  10. Evaluation of Multi-tRNA Synthetase Complex by Multiple Reaction Monitoring Mass Spectrometry Coupled with Size Exclusion Chromatography

    PubMed Central

    Kim, Jun Seok; Lee, Cheolju

    2015-01-01

    Eight aminoacyl-tRNA synthetases (M, K, Q, D, R, I, EP and LARS) and three auxiliary proteins (AIMP1, 2 and 3) are known to form a multi-tRNA synthetase complex (MSC) in mammalian cells. We combined size exclusion chromatography (SEC) with reversed-phase liquid chromatography multiple reaction monitoring mass spectrometry (RPLC-MRM-MS) to characterize MSC components and free ARS proteins in human embryonic kidney (HEK 293T) cells. Crude cell extract and affinity-purified proteins were fractionated by SEC in non-denaturing state and ARSs were monitored in each fraction by MRM-MS. The eleven MSC components appeared mostly in earlier SEC fractions demonstrating their participation in complex formation. TARSL2 and AIMP2-DX2, despite their low abundance, were co-purified with KARS and detected in the SEC fractions, where MSC appeared. Moreover, other large complex-forming ARS proteins, such as VARS and FARS, were detected in earlier fractions. The MRM-MS results were further confirmed by western blot analysis. Our study demonstrates usefulness of combined SEC-MRM analysis for the characterization of protein complexes and in understanding the behavior of minor isoforms or variant proteins. PMID:26544075

  11. Exploration of cardanol-based phenolated and epoxidized resins by size exclusion chromatography and MALDI mass spectrometry.

    PubMed

    Fouquet, Thierry; Puchot, Laura; Verge, Pierre; Bomfim, João A S; Ruch, David

    2014-09-16

    Cardanol and cardanol derivatives are among the most important biobased materials currently investigated in green chemistry, as renewable and promising building blocks in lieu of traditional raw materials from non renewable resources, in particular owing to the olefinic linkages on the C15 alkyl side-chain. Despite the increasing interest they arouse, analytical chemistry dedicated to cardanol and associated resins has been rarely reported in the literature, found even poorer when dealing with chromatography and mass spectrometry. In this work, a thorough molecular characterization was conducted using matrix assisted laser desorption ionization (MALDI) mass spectrometry, size exclusion chromatography (SEC), and SEC-MALDI coupling to gain insights into the composition of phenolated, epoxidized, and epoxidized phenolated cardanol. A nomenclature was proposed to properly describe the numerous species found in these materials, while simulations of the unsaturation patterns and their comparison with the detected patterns in MALDI-MS gave useful details about the phenolation treatment expected to occur on the polyunsaturated C15 side chain. Finally, the SEC-MALDI off-line coupling allowed SEC peaks to be deconvoluted by mass spectrometry and MALDI artefacts related to matrix adduction to be pointed out. PMID:25150696

  12. Reverse-phase ion-pair chromatography (HPLC) (high performance liquid chromatography) of alkylbenzene sulfonates

    SciTech Connect

    Verkruyse, L.A.; Lewis, R.V.; Meyers, K.O.; Salter, S.J.

    1983-01-01

    An HPLC procedure is presented that rapidly and quantitatively separates alkylbenzene sulfonates according to their alkyl chain length and structure. The separation employs octadecylsilanized silica gel as a stationary phase and an aqueous acetonitrile solution of tetrabutyl ammonium chloride (TBAC) as the mobile phase. The TBAC acts as an ion-pair reagent and suppresses the ionic nature of the sulfonates. Separation is effected by gradients in TBAC concentration and mobile phase polarity. The concentration of each component then is quantitatively measured by a UV detector. Gradient selection and sample matrix effects are discussed. Several examples are presented that demonstrate the utility of this analytic procedure. 14 references.

  13. Bioaccumulation of platinum group elements and characterization of their species in Lolium multiflorum by size-exclusion chromatography coupled with ICP-MS.

    PubMed

    Lesniewska, Barbara A; Messerschmidt, Jürgen; Jakubowski, Norbert; Hulanicki, Adam

    2004-04-25

    The bioaccumulation of Pt, Pd and Rh by grass grown hydroponically with nutrient solutions containing these ions at elevated (38.7 mg l(-1) Pt, 21.7 mg l(-1) Pd and 7.1 mg l(-1) Rh) and medium (3.6 mg l(-1) Pt, 4.4 mg l(-1) Pd and 0.5 mg l(-1) Rh) concentrations was studied by using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The highest bioaccumulation factors were obtained for Pd and Rh in roots and for Pt in leaves. The obtained results showed that most of the studied metals were accumulated in roots, and only a small fraction was really metabolised and transported to leaves. The multi-element capability of ICP-SFMS has been exploited to study the metabolism of platinum group elements (PGEs) in cultivated plants. The species of studied metals were extracted from roots and leaves and separated into two mass fractions by ultra-filtration. The low molecular mass (<10 kDa) fractions of the root and the leaf extracts were investigated by size-exclusion chromatography (SEC) coupled on-line to ICP-SFMS. The presence of Ca, Cu, S and C in the same fractions as Pt, Pd and Rh may indicate the interaction of PGEs with phytochelatins and carbohydrates. PMID:15081741

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

    PubMed

    Kim, Hyun-Seok; Huber, Kerry C

    2007-06-27

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

  15. Simultaneous speciation of iron(II) and iron(III) by ion chromatography with chemiluminescence detection.

    PubMed

    Chen, Yun-Chieh; Jian, Yu-Ling; Chiu, Kong-Hwa; Yak, Hwa-Kwang

    2012-01-01

    This study reports on a method for the speciation of iron in aqueous samples by the simultaneous analysis of divalent and trivalent iron ions with ion chromatography equipped with chemiluminescence detection (IC-CLD). Ferrous and ferric ions are first chelated by pyridine-2,6-dicarboxylic acid (PDCA) to form complexed anions, and separated by a mixed-bed ion-exchange column. The separated complexed ions are then detected with a CLD system containing luminol and hydrogen peroxide in a basic solution. This luminescence system has a linear dynamic range of ca. 3 orders of magnitude, with method detection limits as low as 7 g L(-1) for Fe(II) and 3 g L(-1) for Fe(III), measured in the simultaneous detection mode. This system resists interferences from common cations such as Cd, Ca, Cr, Cu, Mg, Ni, Pb, and Zn. Evaluation by analyzing real samples shows that this method is rapid, accurate, sensitive, and selective. PMID:22878635

  16. Fabricating electrospun cellulose nanofibre adsorbents for ion-exchange chromatography

    PubMed Central

    Dods, Stewart R.; Hardick, Oliver; Stevens, Bob; Bracewell, Daniel G.

    2015-01-01

    Protein separation is an integral step in biopharmaceutical manufacture with diffusion-limited packed bed chromatography remaining the default choice for industry. Rapid bind-elute separation using convective mass transfer media offers advantages in productivity by operating at high flowrates. Electrospun nanofibre adsorbents are a non-woven fibre matrix of high surface area and porosity previously investigated as a bioseparation medium. The effects of compression and bed layers, and subsequent heat treatment after electrospinning cellulose acetate nanofibres were investigated using diethylaminoethyl (DEAE) or carboxylate (COO) functionalisations. Transbed pressures were measured and compared by compression load, COO adsorbents were 30%, 70% and 90% higher than DEAE for compressions 1, 5 and 10 MPa, respectively, which was attributed to the swelling effect of hydrophilic COO groups. Dynamic binding capacities (DBCs) at 10% breakthrough were measured between 2000 and 12,000 CV/h (2 s and 0.3 s residence times) under normal binding conditions, and DBCs increased with reactant concentration from 4 to 12 mg BSA/mL for DEAE and from 10 to 21 mg lysozyme/mL for COO adsorbents. Comparing capacities of compression loads applied after electrospinning showed that the lowest load tested, 1 MPa, yielded the highest DBCs for DEAE and COO adsorbents at 20 mg BSA/mL and 27 mg lysozyme/mL, respectively. At 1 MPa, DBCs were the highest for the lowest flowrate tested but stabilised for flowrates above 2000 CV/h. For compression loads of 5 MPa and 10 MPa, adsorbents recorded lower DBCs than 1 MPa as a result of nanofibre packing and reduced surface area. Increasing the number of bed layers from 4 to 12 showed decreasing DBCs for both adsorbents. Tensile strengths were recorded to indicate the mechanical robustness of the adsorbent and be related to packing the nanofibre adsorbents in large scale configurations such as pleated cartridges. Compared with an uncompressed adsorbent, compressions of 1, 5 and 10 MPa showed increases of 30%, 110% and 110%, respectively, for both functionalisations. The data presented show that capacity and mechanical strength can be balanced through compression after electrospinning and is particular to different functionalisations. This trade-off is critical to the development of nanofibre adsorbents into different packing configurations for application and scale up in bioseparation. PMID:25541092

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

    SciTech Connect

    Goheen, Steven C.; Gibbins, Betty M.

    2000-01-01

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

  18. Further application of size-exclusion chromatography combined with small-angle X-ray scattering optics for characterization of biological macromolecules.

    PubMed

    Watanabe, Yasushi; Inoko, Yoji

    2011-02-01

    Size-exclusion chromatography (gel filtration chromatography or gel permeation chromatography) in conjunction with online synchrotron radiation solution small-angle X-ray scattering optics, absorbance, and/or refractive index detectors was further assessed by application of biological macromolecules, such as the hollow sphere protein complex, apoferritin, and a linear polysaccharide, pullulan. The net X-ray scattering patterns of the eluted 24-mer molecule of apoferritin showed the specific character for the hollow spherical shape. The chromatographic (time-resolved) X-ray scattering data of the linear polysaccharide pullulan revealed the flexible chain structure during the chromatographic separation in an aqueous solution. These further applications demonstrated that the present measurement technique will be useful for not only the determination of the radius of gyration value of less than about 10 nm and molecular weight below several hundred thousand but also for the structural characterization of the various macromolecules during the chromatography. PMID:20811739

  19. Fractionation of Aspergillus niger cellulases by combined ion exchange affinity chromatography

    SciTech Connect

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

    1987-02-05

    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.

  20. Multiple applications of ion chromatography oligosaccharide fingerprint profiles to solve a variety of sugar and sugar-biofuel industry problems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugar crops contain a broad variety of carbohydrates used for human consumption and the production of biofuels and bioproducts. Ion chromatography with integrated pulsed amperometric detection (IC-IPAD), also known as high performance anion exchange chromatography (HPAEC), can be used to simultaneo...

  1. Determination of alkylamines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches

    NASA Astrophysics Data System (ADS)

    Huang, R.-J.; Li, W.-B.; Wang, Y.-R.; Wang, Q. Y.; Jia, W. T.; Ho, K.-F.; Cao, J. J.; Wang, G. H.; Chen, X.; Haddad, I. EI; Zhuang, Z. X.; Wang, X. R.; Prévôt, A. S. H.; O'Dowd, C. D.; Hoffmann, T.

    2014-07-01

    In recent years low molecular weight alkylamines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkylamines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkylamines in aerosol particles. Alkylamines were converted to carbamates through derivatization with isobutyl chloroformate for GC-MS determination. A set of parameters affecting the analytical performances of the GC-MS approach, including reagent amount, reaction time and pH value, was evaluated and optimized. The accuracy is 84.3-99.1%, and the limits of detection obtained are 1.8-3.9 pg (or 0.02-0.04 ng m-3). For the IC approach, a solid-phase extraction (SPE) column was used to separate alkylamines from interfering cations before IC analysis. 1-2% (v/v) of acetone (or 2-4% (v/v) of acetonitrile) was added to the eluent to improve the separation of alkylamines on the IC column. The limits of detection obtained are 2.1-15.9 ng (or 0.9-6.4 ng m-3), and the accuracy is 55.1-103.4%. The lower accuracy can be attributed to evaporation losses of amines during the sample concentration procedure. Measurements of ambient aerosol particle samples collected in Hong Kong show that the GC-MS approach is superior to the IC approach for the quantification of primary and secondary alkylamines due to its lower detection limits and higher accuracy.

  2. Determination of alkyl amines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches

    NASA Astrophysics Data System (ADS)

    Huang, R.-J.; Li, W.-B.; Wang, Y.-R.; Wang, Q. Y.; Ho, K.-F.; Cao, J. J.; Wang, G. H.; Chen, X.; Haddad, I. EI; Zhuang, Z. X.; Wang, X. R.; Prévôt, A. S. H.; O'Dowd, C. D.; Hoffmann, T.

    2014-03-01

    In recent years low molecular weight alkyl amines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkyl amines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkyl amines in aerosol particles. Alkyl amines were converted to carbamates through derivatization with isobutyl chloroformate for GC-MS determination. A set of parameters affecting the analytical performances of the GC-MS approach, including reagent amount, reaction time and pH value, was evaluated and optimized. The accuracy is 84.3-99.1%, and the limits of detection obtained are 1.8-3.9 pg. For the IC approach, a solid phase extraction (SPE) column was used to separate alkyl amines from interfering cations before IC analysis. 1-2% (v/v) of acetone (or 2-4% (v/v) of acetonitrile) was added to the eluent to improve the separation of alkyl amines on the IC column. The limits of detection obtained are 2.1-15.9 ng and the accuracy is 55.1-103.4%. The lower accuracy can be attributed to evaporation losses of amines during the sample concentration procedure. Measurements of ambient aerosol particle samples collected in Hong Kong show that the GC-MS approach is superior to the IC approach for the quantification of primary and secondary alkyl amines due to its lower detection limits and higher accuracy.

  3. Calix[4]pyrroles with Shortest Possible Strap: Exclusively Selective toward Fluoride Ion.

    PubMed

    Samanta, Ritwik; Kumar, B Sathish; Panda, Pradeepta K

    2015-09-01

    Four new calix[4]pyrroles with the shortest possible strap so far through ortho-linking of the aromatic unit have been synthesized, including a naphthalene-derived fluorescent receptor. They show exclusive selectivity toward the fluoride ion as confirmed by (1)H NMR, isothermal titration calorimetry, and fluorescence spectroscopic study. Anion affinity could also be modulated further via functionalization at the strap. Computational analysis displays calix[4]pyrroles binding to fluoride ion in a very unusual 1,3-alternate conformation where the anion resides on the opposite side of the strap. PMID:26313641

  4. Quantitative confirmation of dimetridazole and ipronidazole in swine feed by capillary gas chromatography/mass spectrometry with multiple ion detection.

    PubMed

    Morris, W J; Nandrea, G J; Roybal, J E; Munns, R K; Shimoda, W; Skinner, H R

    1987-01-01

    Extracts from 4 types of swine feed containing 0.11 ppm each of dimetridazole (DMZ) and ipronidazole (IPR) were analyzed by capillary gas chromatography/mass spectrometry (GC/MS) using multiple ion detection (MID) techniques. We demonstrate in this paper that the quantitative results obtained by capillary GC/MS with MID are comparable for both compounds to results obtained by liquid chromatography and have a lower coefficient of variation for DMZ. Moreover, consistency in the ion ratios (5 ions in DMZ and 6 ions in IPR) permits identification of these compounds by electron ionization MS. PMID:3624166

  5. On-line gas-free electrodialytic eluent generator for capillary ion chromatography.

    PubMed

    Yang, Bingcheng; Takeuchi, Masaki; Dasgupta, Purnendu K

    2008-01-01

    Both low- and high-pressure, gas-free, capillary-scale electrodialytic generators for eluents in ion chromatography are described. While the low-pressure devices rely on planar or tubular membranes, the high-pressure devices rely on ion-exchange beads used both as one-way ionic gates and as ball-on-seat valves to provide sealing. The high-pressure device is easily implemented in the form of a commercial cross fitting and can withstand at least 1400 psi. By design these devices do not produce gas in the eluent channel; hence, it is not necessary to remove gas afterward. With appropriate electrolytes and electrode polarities, such devices can produce either acid or base or salt. In regard to ionic transport, the behavior of these devices fully corresponds to that of a semiconductor diode. To our knowledge, this is the first time such complete equivalence of ion transport through ion-exchange media and with the more familiar example of electron transport through a semiconductor diode under both forward- and reverse-biased conditions have been demonstrated. Reverse bias can be applied to minimize/prevent Donnan-forbidden leakage or ion exchange. Even with 4 M KOH in the electrode compartments and 4 microL/min water flowing through the eluent channel, with a reverse bias of -12 V, the leakage KOH concentration is <30 microM, whereas the KOH concentration with zero voltage applied, herein after termed open circuit penetration (OCP), is 1600 microM. It is suggested that this OCP occurs not as much through Donnan-forbidden leakage but via ion exchange. Chromatograms and reproducibility data are presented for both isocratic and gradient chromatography, using ion-exchange, latex-modified, open tubular and packed monolithic columns. PMID:18062705

  6. Determination of fungicide residues in baby food by liquid chromatography-ion trap tandem mass spectrometry.

    PubMed

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

    2012-11-15

    Current European Commission Directives on foods for infants and young children places emphasis on the control of pesticide residues at levels below 10 μg kg(-1). In the present work, a liquid chromatography electrospray ionisation ion trap tandem mass spectrometry (LC-Ion Trap-MS/MS) has been developed for the multiresidue of 10 multiclass fungicides (carbendazim, thiabendazole, imazalil, tridemorph, triadimefon, bitertanol, prochloraz, flutriafol, myclobutanil and diphenylamine) in fruit-based baby food. The developed method is based on a simple sample treatment (QuEChERS), which consists of a liquid-liquid extraction using acetonitrile, followed by a clean-up step based on dispersive solid-phase extraction with primary secondary amine (PSA). Subsequent identification and quantitation was accomplished by liquid chromatography/electrospray tandem mass spectrometry using an ion-trap mass spectrometer in the product ion scan MS/MS mode. Matrix effects were evaluated in LC-MS and LC-MS/MS mode experiments, obtaining a reduction of these effects when working in MS/MS mode for most of the analytes. Limits of detection (LOD) were between 0.5 and 3.0 μg kg(-1) depending on the pesticide studied, all being within European Union regulations for baby food. Finally, the proposed method was applied to 25 baby food samples obtained from local supermarkets. Imazalil, thiabendazole and carbendazim were detected in the studied samples. However, none of the samples tested were found to be upper the EU standard. PMID:22868159

  7. Separation of boron from borated paraffin wax by pyrohydrolysis and alkali extraction methods and its determination using ion chromatography.

    PubMed

    Raut, Vaibhavi Vishwajeet; Jeyakumar, Subbiah; Shah, Dipti Jayesh; Thakur, Uday Kumar; Tomar, Bhupendra Singh; Ramakumar, Karanam Lakshminarayana

    2015-01-01

    A method based on the pyrohydrolysis extraction of boron and its quantification with ion chromatography was proposed for paraffin waxes borated with H3BO3 and B4C. The optimum pyrohydrolysis conditions were identified. Wax samples were mixed with U3O8, which prevents the sample from flare up, and also accelerates the extraction of boron. Pyrohydrolysis was carried out with moist O2 at 950C for 60 and 90 min for wax with H3BO3 and wax with B4C, respectively. Two simple methods of separation based on alkali extraction and melting wax in alkali were also developed exclusively for wax with H3BO3. In all the separations, the recovery of B was above 98%. During IC separation, B was separated as boron-mannitol anion complex. Linear calibration was obtained it between 0.1 and 50 ppm of B, and LOD was calculated as 5 ppb (S/N = 3). The reproducibility was better than 5% (RSD). PMID:25765277

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

    SciTech Connect

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

    2007-07-01

    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.

  9. [An assay for anti-factor Xa activity of low molecular weight heparins by high performance liquid size exclusion chromatography].

    PubMed

    Zhang, Qianqian; Kang, Jingwu

    2013-07-01

    The "gold standard" assay for monitoring low molecular weight heparins (LMWHs) activity is the chromogenic-based anti-factor Xa assay. The methodology of an anti-factor Xa assay is that LMWH is added to a known amount of excess factor Xa and excess antithrombin. It will bind to antithrombin and form a triplet complex with factor Xa, inhibiting the activity of factor Xa. However, the residual factor Xa can still hydrolyze chromogenic peptide substrate, releasing the chromophore for photometric detection. The absorbance is inversely proportional to the amount of heparin/LMWH. The results are given in anticoagulant concentration in units/ mL of anti-factor Xa, such that high values indicate high levels of anticoagulation and low values indicate low levels of anticoagulation. Herein, a novel assay method for anti-FXa activity of LMWHs using high performance liquid size exclusion chromatography (SEC) is reported, in which antithrombin III (AT Ill ) was diluted by the buffer solution contained LMWHs. Subsequently, exogenous FXa and p-nitroaniline coupled peptide substrate were added and incubated for a period, separately. The resulting mixture was separated based on size by SEC, and the free chromophore p-nitroaniline can be detected at an absorption maximum of 385 nm without interference from the absorbance of p-nitroanilide substrates. Moreover, the measurements are not influenced by sample opacity or turbidity, so it is possible to test various complex samples, such as plasma. The assay is robust, sensitive, and cost effective. PMID:24164039

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

    SciTech Connect

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

    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.

  12. Expanding the Chemical Cross-Linking Toolbox by the Use of Multiple Proteases and Enrichment by Size Exclusion Chromatography*

    PubMed Central

    Leitner, Alexander; Reischl, Roland; Walzthoeni, Thomas; Herzog, Franz; Bohn, Stefan; Förster, Friedrich; Aebersold, Ruedi

    2012-01-01

    Chemical cross-linking in combination with mass spectrometric analysis offers the potential to obtain low-resolution structural information from proteins and protein complexes. Identification of peptides connected by a cross-link provides direct evidence for the physical interaction of amino acid side chains, information that can be used for computational modeling purposes. Despite impressive advances that were made in recent years, the number of experimentally observed cross-links still falls below the number of possible contacts of cross-linkable side chains within the span of the cross-linker. Here, we propose two complementary experimental strategies to expand cross-linking data sets. First, enrichment of cross-linked peptides by size exclusion chromatography selects cross-linked peptides based on their higher molecular mass, thereby depleting the majority of unmodified peptides present in proteolytic digests of cross-linked samples. Second, we demonstrate that the use of proteases in addition to trypsin, such as Asp-N, can additionally boost the number of observable cross-linking sites. The benefits of both SEC enrichment and multiprotease digests are demonstrated on a set of model proteins and the improved workflow is applied to the characterization of the 20S proteasome from rabbit and Schizosaccharomyces pombe. PMID:22286754

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

    SciTech Connect

    Johnson, B.R.; Bartle, K.D.; Herod, A.A.; Kandiyoti, R.

    1995-12-31

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

  14. Size-exclusion chromatography of ultrahigh molecular weight methylcellulose ethers and hydroxypropyl methylcellulose ethers for reliable molecular weight distribution characterization.

    PubMed

    Li, Yongfu; Shen, Hongwei; Lyons, John W; Sammler, Robert L; Brackhagen, Meinolf; Meunier, David M

    2016-03-15

    Size-exclusion chromatography (SEC) coupled with multi-angle laser light scattering (MALLS) and differential refractive index (DRI) detectors was employed for determination of the molecular weight distributions (MWD) of methylcellulose ethers (MC) and hydroxypropyl methylcellulose ethers (HPMC) having weight-average molecular weights (Mw) ranging from 20 to more than 1,000kg/mol. In comparison to previous work involving right-angle light scattering (RALS) and a viscometer for MWD characterization of MC and HPMC, MALLS yields more reliable molecular weight for materials having weight-average molecular weights (Mw) exceeding about 300kg/mol. A non-ideal SEC separation was observed for cellulose ethers with Mw>800kg/mol, and was manifested by upward divergence of logM vs. elution volume (EV) at larger elution volume at typical SEC flow rate such as 1.0mL/min. As such, the number-average molecular weight (Mn) determined for the sample was erroneously large and polydispersity (Mw/Mn) was erroneously small. This non-ideality resulting in the late elution of high molecular weight chains could be due to the elongation of polymer chains when experimental conditions yield Deborah numbers (De) exceeding 0.5. Non-idealities were eliminated when sufficiently low flow rates were used. Thus, using carefully selected experimental conditions, SEC coupled with MALLS and DRI can provide reliable MWD characterization of MC and HPMC covering the entire ranges of compositions and molecular weights of commercial interest. PMID:26794765

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

    USGS Publications Warehouse

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

    1999-01-01

    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.

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

    PubMed Central

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

    2010-01-01

    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

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

    PubMed

    Happel, Oliver; Seubert, Andreas

    2006-03-01

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

  18. Ultraperformance ion-pairing liquid chromatography with on-line electrospray ion trap mass spectrometry for heparin disaccharide analysis

    PubMed Central

    Yang, Bo; Weyers, Amanda; Baik, Jong Youn; Sterner, Eric; Sharfstein, Susan; Mousa, Shaker A.; Zhang, Fuming; Dordick, Jonathan S.; Linhardt, Robert J.

    2011-01-01

    A high resolution method for the separation and analysis of disaccharides prepared from heparin and heparan sulfate (HS) using heparin lyases is described. Ultraperformance liquid chromatography in a reverse-phase, ion-pairing mode efficiently separates eight heparin/HS disaccharides. The disaccharides can then be detected and quantified using electrospray ionization mass spectrometry. This method is particularly useful in the analysis of small amounts of biological samples, including cells, tissues and biological fluids, as it provides high sensitivity without being subject to interference from proteins, peptides and other sample impurities. PMID:21530482

  19. Quantitative lipoxygenase product profiling by gas chromatography negative-ion chemical ionization mass spectrometry.

    PubMed

    Lehmann, W D; Metzger, K; Stephan, M; Wittig, U; Zalán, I; Habenicht, A J; Fürstenberger, G

    1995-01-01

    An assay for the quantitative determination of the hydroxylation profile of long-chain fatty acids is described for gas chromatography negative-ion chemical ionization mass spectrometry and stable isotope dilution using [carboxyl-18O2]-labeled internal standards. The assay has been applied to the study of fatty acids isolated from body fluids, tissue, and cultured cells. Examples for the analyses of biological systems expressing 5-, 8-, 12-, or 15-lipoxygenase activity are given and the most important sources of analytical errors are addressed. Increased specificity compared to analysis by negative-ion chemical ionization, at the cost of sensitivity, can be achieved by the use of positive-ion electron impact ionization for the investigation of hydrogenated pentafluorobenzylester/trimethylsilylether derivatives. The method described provides complete, specific, and quantitative profiles of hydroxylated fatty acids originally present in biological samples or generated in vitro by incubation with polyunsaturated fatty acid substrates such as linoleic or arachidonic acid. PMID:7710076

  20. Determination of residual pesticides in olive oil by GC-MS and HPLC-MS after extraction by size-exclusion chromatography.

    PubMed

    Barrek, Sami; Paisse, Olivier; Grenier-Loustalot, Marie-Florence

    2003-06-01

    This work describes the development of a method for analyzing pesticide residues in olive oil by GC-MS and HPLC-MS. Pesticides were separated from the oily matrix by size-exclusion chromatography. After extraction, 20 pesticides were separated and analyzed by GC-MS and 11 others HPLC-MS in electrospray mode. The development of this method enabled us to identify and quantify the pesticides of interest. PMID:12728294

  1. Simultaneous determination of inorganic anions, calcium and magnesium by suppressed ion chromatography.

    PubMed

    García-Fernández, Ruben; García-Alonso, J Ignacio; Sanz-Medel, Alfredo

    2004-04-01

    Suppressed conductimetric detection ion chromatography (IC) was investigated for the separation and detection of common inorganic anions, calcium and magnesium by anion-exchange chromatography using a sodium carbonate-EDTA mobile phase. The formation of anionic Ca2+ -EDTA and Mg2+ -EDTA complexes allowed its separation from other inorganic anions opening the way for their simultaneous determination in a single chromatographic run. The effect of the pH, carbonate and EDTA concentrations in the eluent and the previous addition of EDTA to the samples has been studied. The optimised experimental conditions were applied to the determination of Ca2+ and Mg2+ in mineral waters with results in agreement with alternative ICP-MS methodologies. PMID:15072297

  2. Determination of oxidation products in radiolysis of halophenols with pulse radiolysis, hplc, and ion chromatography

    SciTech Connect

    Ye, M. ); Schuler, R.H. )

    1990-01-01

    This paper reports on hydroxyl radicals that react with halogen substituted phenols by several different ways. One is addition of OH radicals to the aromatic ring, which is followed by elimination of hydrogen halide, H{sub 2}O or H{sup {minus}}. The positions of OH radicals attack are dependent on the nature of the halogen which affects the electronic distribution in the ring. The oxidation of fluorophenols, chlorophenols and bromophenols with hydroxyl radicals in N{sub 2}O saturated solution has been investigated with pulse radiolysis and {gamma}-irradiation experiments. The intermediates of the reactions were studied by pulse radiolysis. The products created in the {gamma}-irradiation of aqueous solutions of halophenols were analyzed by ion chromatography and high performance liquid chromatography (HPLC). With the combination of time-resolved and steady-state experiments a complete and detailed description of radiolytic oxidation of halophenols by hydroxyl radicals was obtained.

  3. Simulation model for overloaded monoclonal antibody variants separations in ion-exchange chromatography.

    PubMed

    Guélat, Bertrand; Ströhlein, Guido; Lattuada, Marco; Delegrange, Lydia; Valax, Pascal; Morbidelli, Massimo

    2012-08-31

    A model was developed for the design of a monoclonal antibody charge variants separation process based on ion-exchange chromatography. In order to account for a broad range of operating conditions in the simulations, an explicit pH and salt concentration dependence has been included in the Langmuir adsorption isotherm. The reliability of this model was tested using experimental chromatographic retention times as well as information about the structural characteristics of the different charge variants, e.g. C-terminal lysine groups and deamidated groups. Next, overloaded isocratic elutions at various pH and salt concentrations have been performed to determine the saturation capacity of the ion-exchanger. Furthermore, the column simulation model was applied for the prediction of monoclonal antibody variants separations with both pH and salt gradient elutions. A good prediction of the elution times and peak shapes was observed, even though none of the model parameters was adjusted to fit the experimental data. The trends in the separation performance obtained through the simulations were generally sufficient to identify the most promising operating conditions. The predictive column simulation model thus developed in this work, including a set of parameters determined through specific independent experiments, was experimentally validated and offers a useful basis for a rational optimization of monoclonal antibody variants separation processes on ion-exchange chromatography. PMID:22795935

  4. Capillary ion-exchange chromatography with nanogram sensitivity for the analysis of monoclonal antibodies.

    PubMed

    Rea, Jennifer C; Freistadt, Benny S; McDonald, Daniel; Farnan, Dell; Wang, Yajun Jennifer

    2015-12-11

    Ion-exchange chromatography (IEC) is widely used for profiling the charge heterogeneity of proteins, including monoclonal antibodies (mAbs). Despite good resolving power and robustness, ionic strength-based ion-exchange separations are generally product specific and can be time consuming to develop. In addition, conventional analytical scale ion-exchange separations require tens of micrograms of mAbs for each injection, amounts that are often unavailable in sample-limited applications. We report the development of a capillary IEC (c-IEC) methodology for the analysis of nanogram amounts of mAb charge variants. Several key modifications were made to a commercially available liquid chromatography system to perform c-IEC for charge variant analysis of mAbs with nanogram sensitivity. We demonstrate the method for multiple monoclonal antibodies, including antibody fragments, on different columns from different manufacturers. Relative standard deviations of <10% were achieved for relative peak areas of main peak, acidic and basic regions, which are common regions of interest for quantifying monoclonal antibody charge variants using IEC. The results herein demonstrate the excellent sensitivity of this c-IEC characterization method, which can be used for analyzing charge variants in sample-limited applications, such as early-stage candidate screening and in vivo studies. PMID:26596872

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

    USGS Publications Warehouse

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

    1996-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Andersson, Alexandra; Persson, Tobias; Zacchi, Guido; Stlbrand, Henrik; Jnsson, Ann-Sofi

    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.

  7. Isolation of Exosomes from Blood Plasma: Qualitative and Quantitative Comparison of Ultracentrifugation and Size Exclusion Chromatography Methods

    PubMed Central

    Baranyai, Tamás; Herczeg, Kata; Onódi, Zsófia; Voszka, István; Módos, Károly; Marton, Nikolett; Nagy, György; Mäger, Imre; Wood, Matthew J.; El Andaloussi, Samir; Pálinkás, Zoltán; Kumar, Vikas; Nagy, Péter; Kittel, Ágnes; Buzás, Edit Irén; Ferdinandy, Péter; Giricz, Zoltán

    2015-01-01

    Background Exosomes are emerging targets for biomedical research. However, suitable methods for the isolation of blood plasma-derived exosomes without impurities have not yet been described. Aim Therefore, we investigated the efficiency and purity of exosomes isolated with potentially suitable methods; differential ultracentrifugation (UC) and size exclusion chromatography (SEC). Methods and Results Exosomes were isolated from rat and human blood plasma by various UC and SEC conditions. Efficiency was investigated at serial UC of the supernatant, while in case of SEC by comparing the content of exosomal markers of various fractions. Purity was assessed based on the presence of albumin. We found that the diameter of the majority of isolated particles fell into the size range of exosomes, however, albumin was also present in the preparations, when 1h UC at 4°C was applied. Furthermore, with this method only a minor fraction of total exosomes could be isolated from blood as deduced from the constant amount of exosomal markers CD63 and TSG101 detected after serial UC of rat blood plasma samples. By using UC for longer time or with shorter sedimentation distance at 4°C, or UC performed at 37°C, exosomal yield increased, but albumin impurity was still observed in the isolates, as assessed by transmission electron microscopy, dynamic light scattering and immunoblotting against CD63, TSG101 and albumin. Efficiency and purity were not different in case of using further diluted samples. By using SEC with different columns, we have found that although a minor fraction of exosomes can be isolated without significant albumin content on Sepharose CL-4B or Sephacryl S-400 columns, but not on Sepharose 2B columns, the majority of exosomes co-eluted with albumin. Conclusion Here we show that it is feasible to isolate exosomes from blood plasma by SEC without significant albumin contamination albeit with low vesicle yield. PMID:26690353

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

    PubMed

    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

    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 (α-casein, β-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

  9. Indirect determination of cyanide compounds by ion chromatography with conductivity measurement

    SciTech Connect

    Nonomura, M.

    1987-09-01

    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.

  10. Direct injection of native aqueous matrices by achiral-chiral chromatography ion trap mass spectrometry for simultaneous quantification of pantoprazole and lansoprazole enantiomers fractions.

    PubMed

    Barreiro, Juliana Cristina; Vanzolini, Kenia Lourenço; Cass, Quezia Bezerra

    2011-05-20

    A two-dimensional liquid chromatography system coupled to ion-trap tandem mass spectrometer (2DLC-IT-MS/MS) was employed for the simultaneous quantification of pantoprazole and lansoprazole enantiomers fractions. A restricted access media of bovine serum albumin octyl column (RAM-BSA C(8)) was used in the first dimension for the exclusion of the humic substances, while a polysaccharide-based chiral column was used in the second dimension for the enantioseparation of both pharmaceuticals. The results described here show good selectivity, extraction efficiency, accuracy, and precision with detection limits of 0.200 and 0.150 μg L(-1) for the enatiomers of pantoprazole and lansoprazole respectively, while employing a small amount (1.0 mL) of native water sample per injection. This work reports an innovative assay for monitoring work, studies of biotic and abiotic enantioselective degradation and temporal changes of enantiomeric fractions. PMID:21429496

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  12. Suppressed ion chromatography for monitoring chemical impurities in steam for geothermal power plants.

    PubMed

    Santoyo, E; Verma, S P; Sandoval, F; Aparicio, A; García, R

    2002-03-01

    A suppressed ion chromatography (IC) technique has been evaluated as a chemical monitoring tool for detecting major anions (F-, Cl-, NO3- and SO4(2-)) of condensed steam in geothermal power plants. It is shown that the suppressed IC technique provides a suitable means for preventing possible damage to generating equipment in the geothermal industry. An electrical conductivity detector (0.1 microS sensitivity) with an anion-exchange column (IonPac AS4A-SC), a micro-membrane suppressor (AMMS II), and an isocratic high-pressure pump system were successfully used for detecting low concentrations of inorganic anions. Method detection limits for the anions of interest were <0.184 mg/L. Details of the IC methodology as well as some experimental results obtained during its application for the chemical monitoring of geothermal steam pipes are also described. PMID:11999745

  13. The removal of uranium from acidic media using ion exchange and/or extraction chromatography

    SciTech Connect

    FitzPatrick, J.R.; Schake, B.S.; Murphy, J.; Holmes, K; West, M.H.

    1996-06-01

    The separation and purification of uranium from either nitric acid or hydrochloric acid media can be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-addition, waste stream polishing is associated with this effort in order to achieve more complete removal of uranium prior to recycle of the acid. Extraction chromatography has been demonstrated to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps.

  14. [Content determination of dencichine in Panax Notoginseng by a reversed phase ion-pair chromatography].

    PubMed

    Li, Lin; Wang, Cheng-xiao; Qu, Yuan; Cui, Xiu-ming

    2015-10-01

    To build a reversed phase ion-pair chromatography to determination content of Dencichine from Panax notoginseng. Using Tetrabutyl ammonium hydroxide ions by the combination of reagent and HPLC method without derivatization to test the content of dencichine directly. The optimum conditions of supersonic extraction were solid-to-liquid ratio 1: 20, Continuous ultrasonic extraction: twice, each time 15 minutes; 3,500 r · min⁻¹, then centrifuging 15 minutes. Dencichine in different age, place, part and the different Processing mode were examined. The method is simple with sound separation degree and stability, which can facilitate the determination of dencichine content directly and provide the basis in quality standard of raw material. PMID:27062822

  15. [Simultaneous determination of ammonium and six alkylamines in cosmetics by ion chromatography].

    PubMed

    Zhong, Zhixiong; Li, Gongke; Zhu, Binghui; Luo, Zhibin; Wu, Ximei

    2010-07-01

    A method for the simultaneous determination of ammonium and six alkylamines in cosmetic products by ion chromatography (IC) was developed. The sample pretreatment process and the separation resolution of chromatography were investigated. The samples were extracted by 100 mmol/L acetic acid-20% (v/v) acetonitrile solution at room temperature, and then solid phase extraction (SPE) column was used to eliminate the interferences. The influences of pH value, organic solvent and coexisted ions were investigated. The separation was carried out on IonPac CS17 (250 mm x 4 mm)analytical column and IonPac CG17 (50 mm x 4 mm)guard column using 1.5 - 15 mmol/L methanesulfonic acid and 0.5% - 5% (v/v) acetonitrile gradient elution at a flow rate of 1.0 mL/min at 24 degrees C, coupled with suppressed conductivity detector. Under the optimum conditions, a measurement could be completed less than 26 min. The linearity ranged from 0.3 to 15 mg/L, the detection limits and the quantification limits were in the ranges of 2.1 - 7.9 mg/kg and 7 - 26 mg/kg, respectively. The method was successfully employed for the determination of ammonium, methylamine, dimethylamine, trimethylamine, ethylamine, propylamine and butylamine in samples including cleaning, body lotion, skin-bleaching, sun block, marcel, hair dye and pilatory cosmetics with the recoveries of 80.2% - 109.2% and the relative standard deviations (RSDs) of 0.5% - 3.1%. The method offered high selectivity, sensitivity, and gave satisfactory results for real sample analysis. PMID:21046791

  16. Computer-assisted multi-segment gradient optimization in ion chromatography.

    PubMed

    Tyteca, Eva; Park, Soo Hyun; Shellie, Robert A; Haddad, Paul R; Desmet, Gert

    2015-02-13

    This study reports simulation and optimization of ion chromatography separations using multi-segment gradient elution. First, an analytical expression for the gradient retention factor under these complex elution profiles was derived. This allows a rapid retention time prediction calculations under different gradient conditions, during computer-assisted method development. Next, these analytical expressions were implemented in an in-house written Matlab(®) routine that searches for the optimal (multi-segment) gradient conditions, either via a four-segment grid search or via the recently proposed one-segment-per-component search, in which the slope is adjusted after the elution of each individual component. Evaluation of the retention time simulation and optimization approaches was performed on a mixture of 18 inorganic anions and different subsets with varying number of compounds. The two considered multi-segment gradient optimization searches resulted in similar proposed gradient profiles, and corresponding chromatograms. Moreover, the resultant chromatograms were clearly superior to the chromatograms obtained from the best simple linear gradient profiles, found via a fine grid search. The proposed approach is useful for automated method development in ion chromatography in which complex elution profiles are often used to increase the separation power. PMID:25596760

  17. The principle of pooled calibrations and outlier retainment elucidates optimum performance of ion chromatography.

    PubMed

    Andersen, Jens E T; Mikolajczak, Maria; Wojtachnio-Zawada, Katarzyna Olga; Nicolajsen, Henrik Vigan

    2012-11-01

    A principle with quality assurance of ion chromatography (IC) is presented. Since the majority of scientists and costumers are interested in the determination of the true amount of analyte in real samples, the focus of attention should be directed towards the concept of accuracy rather than focussing on precision. By exploiting the principle of pooled calibrations and retainment of all outliers it was possible to obtain full correspondence between calibration uncertainty and repetition uncertainty, which for the first time evidences statistical control in experiments with ion chromatography. Anions of bromide were analysed and the results were subjected to quality assurance (QA). It was found that the limit of quantification (LOQ) was significantly underestimated by up to a factor of 30 with respect to the determination of concentration of unknowns. The concept of lower-limit of analysis (LLA) and upper-limit of analysis (ULA) were found to provide more acceptable limits with respect to reliable analysis with a limited number of repetitions. An excellent correspondence was found between calibration uncertainty and repetition uncertainty. These findings comply with earlier investigations of method validations where it was found that the principle of pooled calibrations provides a more realistic picture of the analytical performance with the drawback, however, that generally higher levels of uncertainties should be accepted, as compared to contemporary literature values. The implications to the science analytical chemistry in general and to method validations in particular are discussed. PMID:23040989

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

    PubMed Central

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

    2011-01-01

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

  19. Quantitation of diethylene glycol and its metabolites by gas chromatography mass spectrometry or ion chromatography mass spectrometry in rat and human biological samples.

    PubMed

    Perala, Adam W; Filary, Mark J; Bartels, Michael J; McMartin, Kenneth E

    2014-05-01

    The misuse of the commonly used chemical diethylene glycol (DEG) has lead to many poisonings worldwide. Methods were developed for analysis of DEG and its potential metabolites; ethylene glycol, glycolic acid, oxalic acid, diglycolic acid and hydroxyethoxy acetic acid in human urine, serum and cerebrospinal fluid samples, collected following a DEG-associated poisoning in the Republic of Panama during 2006. In addition, methods were developed for rat blood, urine, kidney and liver tissue to support toxicokinetic analysis during the conduct of DEG acute toxicity studies in the rat. Sample analysis was conducted using two techniques; ion chromatography with suppressed conductivity and negative ion electrospray ionization with MS detection or with gas chromatography using electron impact ionization or methane negative chemical ionization with MS detection. Stable-isotope-labeled analogs of each analyte were employed as quantitative internal standards in the assays. PMID:24668490

  20. 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

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

    2012-11-01

    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

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

    PubMed

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

    2002-11-01

    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

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

    PubMed

    Kadnar, Rainer; Madera, Martin; Schlifke, Ruth

    2003-05-16

    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

  3. Trace enrichment and separation of metal ions as dithiocarbamate complexes by liquid chromatography

    SciTech Connect

    Irth, H.; de Jong, G.J.; Brinkman, U.A.T.; Frei, R.W.

    1987-01-01

    A method is presented that involves the simultaneous formation of metal dithiocarbamates and on-line preconcentration and, subsequently, separation of heavy-metal ions (Cd(II), Pb(II), Hg(II), Cu(II), Co(II), Ni(II), Bi(III)) by reversed-phase liquid chromatography. A cetrimide-dithiocarbamate ion pair is loaded onto a precolumn packed with C/sub 18/-bonded silica, and the injected metal ions react instantaneously with the dithiocarbamate to form stable complexes. These relatively apolar complexes are efficiently preconcentrated on the precolumn. They can be eluted on-line to C/sup 18/ separation column and, next, separated with an acetonitrile/water gradient containing cetrimide and buffered to pH 6.8. The detection is effected with a UV-vis diode-array detector which allows the determination of subnanogram amounts of metal ions. The cleanup, preconcentration, and automation potential render the method suitable for multimetal analysis in complex samples. Application of this principle to the trace analysis of Cu(II) and Hg(II) in drinking water is demonstrated.

  4. Application of retention modelling to the simulation of separation of organic anions in suppressed ion chromatography.

    PubMed

    Zakaria, Philip; Dicinoski, Greg W; Ng, Boon Khing; Shellie, Robert A; Hanna-Brown, Melissa; Haddad, Paul R

    2009-09-18

    The ion-exchange separation of organic anions of varying molecular mass has been demonstrated using ion chromatography with isocratic, gradient and multi-step eluent profiles on commercially available columns with UV detection. A retention model derived previously for inorganic ions and based solely on electrostatic interactions between the analytes and the stationary phase was applied. This model was found to accurately describe the observed elution of all the anions under isocratic, gradient and multi-step eluent conditions. Hydrophobic interactions, although likely to be present to varying degrees, did not limit the applicability of the ion-exchange retention model. Various instrumental configurations were investigated to overcome problems associated with the use of organic modifiers in the eluent which caused compatibility issues with the electrolytically derived, and subsequently suppressed, eluent. The preferred configuration allowed the organic modifier stream to bypass the eluent generator, followed by subsequent mixing before entering the injection valve and column. Accurate elution prediction was achieved even when using 5-step eluent profiles with errors in retention time generally being less than 1% relative standard deviation (RSD) and all being less than 5% RSD. Peak widths for linear gradient separations were also modelled and showed good agreement with experimentally determined values. PMID:19683244

  5. Ion-pair reversed phase liquid chromatography with ultraviolet detection for analysis of ultraviolet transparent cations.

    PubMed

    He, Yan; Cook, Kenneth S; Littlepage, Eric; Cundy, John; Mangalathillam, Ratish; Jones, Michael T

    2015-08-21

    This paper describes the use of an anionic ion-pair reagent (IPR) to impove the ultraviolet (UV) detection and hydrophobic retention of polar and UV transparent cations. Anionic IPR added to the mobile phase forms an ion-pair with cations. Formation of the ion-pair causes a redshift in the absorption wavength, making it possible for direct UV detection of UV-inactive cations. The ion-pairs with increased hydrophobicity were separated by reversed phase liquid chromatography (RPLC). Different perfluorinated caboxylic acids (trifluoroacetic acid, heptafluorobutyric acid, nonafluoropentanoic acid) were evaluted as IPR in the separation and detection of the common cations sodium, ammonium and Tris(hydroxymethyl)aminomethane (Tris). The effects of the IPR type and concentration on separation and detection have been investigated to understand the separation and detection mechanisms. The optimal separation and detection condtions were attained with mobile phase containing 0.1% nonafluoropentanoic acid and with the UV detection at 210nm. UV detection and charged aerosol detection (CAD) were compared in the quantitation of the cations. The limit of quantitation (LOQ) of sodium and Tris with UV detection is comparable to that by CAD. The LOQ of ammonium with UV detection (1ppm or 3ng) is about 20-fold lower than that (20ppm or 60ng) by CAD. The RPLC-UV method was used to monitor ammonium clearance during ultrafiltration and diafiltration in the manfucaturing of biopharmceutical drug substance. PMID:26195039

  6. Ion chromatography for the separation of heparin and structurally related glycoaminoglycans: A review.

    PubMed

    Fasciano, Jennifer M; Danielson, Neil D

    2016-03-01

    The global crisis resulting from adulterated heparin in late 2007 and early 2008 revived the importance of analytical techniques for the purity analysis of heparin products. The utilization of ion chromatography techniques for the separation, detection, and structural determination of heparin and structurally related glycoaminoglycans, including their corresponding oligosaccharides, has become increasingly important. This review summarizes the primary HPLC approaches, particularly strong anion exchange, weak ion exchange, and reversed-phase ion-pair, used for heparin purity analysis as well as structural characterization. Strong anion exchange HPLC has been studied most extensively and currently offers the best separation of crude heparin and heparin-like compounds. Weak anion exchange HPLC has been shown to provide shorter analysis times with lower salt concentrations in the mobile phase but is not as widely developed for the separation of all glycoaminoglycans of interest. Reversed-phase ion-pair HPLC offers fast and effective separations of oligosaccharides derived from glycoaminoglycans that can be coupled to mass spectrometry for structural analysis. However, this method generally does not provide sufficient retention of intact glycoaminoglycans. PMID:26800335

  7. Resolution and quantitation of apolipoproteins A-I and A-II from human high-density lipoprotein by size exclusion high-performance liquid chromatography.

    PubMed

    Young, P M; Boehm, T M; Brown, J E

    1984-11-01

    Apolipoproteins A-I and A-II, extracted from human high-density lipoprotein (HDL), were resolved and quantified by size exclusion high-performance liquid chromatography on TSK 125 and TSK 250 analytical columns connected in series without the use of chemical denaturants or detergents in the eluent buffer. The columns were pre-equilibrated with a solution containing 0.1 M sodium phosphate, pH 7.2, 0.2 M sodium chloride at a flow-rate of 1 ml/min. Delipidated HDL (1 mg protein per ml) was resolved into two populations of apolipoprotein (apo) A-I: one representing the apo A-I monomer and the other, a self-associated form with a molecular weight of approximately 120,000 daltons. The column eluates were screened for immunoreactivity to apo A peptides, and the identity of each peak was confirmed by sodium dodecyl sulfate--polyacrylamide gel electrophoresis followed by immunoblot analysis. Apo A-I peptides isolated by high-performance liquid chromatography disrupted unilamellar phospholipid vesicles to form smaller phospholipid particles that eluted on gel filtration columns within the size range of HDL. Thus, a rapid method for the isolation and quantitation of non-denatured apolipoproteins from HDL has been developed using size exclusion high-performance liquid chromatography. PMID:6440900

  8. Investigating effects of sample pretreatment on protein stability using size-exclusion chromatography and high-resolution continuum source atomic absorption spectrometry.

    PubMed

    Rakow, Tobias; El Deeb, Sami; Hahne, Thomas; El-Hady, Deia Abd; AlBishri, Hassan M; Wätzig, Hermann

    2014-09-01

    In this study, size-exclusion chromatography and high-resolution atomic absorption spectrometry methods have been developed and evaluated to test the stability of proteins during sample pretreatment. This especially includes different storage conditions but also adsorption before or even during the chromatographic process. For the development of the size exclusion method, a Biosep S3000 5 μm column was used for investigating a series of representative model proteins, namely bovine serum albumin, ovalbumin, monoclonal immunoglobulin G antibody, and myoglobin. Ambient temperature storage was found to be harmful to all model proteins, whereas short-term storage up to 14 days could be done in an ordinary refrigerator. Freezing the protein solutions was always complicated and had to be evaluated for each protein in the corresponding solvent. To keep the proteins in their native state a gentle freezing temperature should be chosen, hence liquid nitrogen should be avoided. Furthermore, a high-resolution continuum source atomic absorption spectrometry method was developed to observe the adsorption of proteins on container material and chromatographic columns. Adsorption to any container led to a sample loss and lowered the recovery rates. During the pretreatment and high-performance size-exclusion chromatography, adsorption caused sample losses of up to 33%. PMID:24964383

  9. Anion exchangers with branched functional ion exchange layers of different hydrophilicity for ion chromatography.

    PubMed

    Shchukina, O I; Zatirakha, A V; Smolenkov, A D; Nesterenko, P N; Shpigun, O A

    2015-08-21

    Novel polystyrene-divinylbenzene (PS-DVB) based anion exchangers differing from each other in the structure of the branched functional ion exchange layer are prepared to investigate the role of linker and functional site on ion exchange selectivity. The proposed method of synthesis includes the obtaining of aminated PS-DVB particles by means of their acylation with following reductive amination with methylamine. Further modification of the obtained secondary aminogroups is provided by the alkylation with either 1,4-butanediol diglycidyl ether (1,4-BDDGE) or resorcinol diglycidyl ether (RDGE), which form the linkers of different hydrophobicity, and amination of terminal epoxide rings with trimethylamine (TMA), dimethylethanolamine (DMEA), methyldiethanolamine (MDEA) or triethanolamine (TEA). The variation of the structure and hydrophobicity of the linker and terminal quaternary ammonium sites in the functional layer allows the alteration of selectivity and separation efficiency of the obtained adsorbents. The ion exchange selectivity and separation efficiency of the anion exchangers are evaluated using the model mixtures of anions (F(-), HCOO(-), Cl(-), NO2(-), Br(-), NO3(-), HPO4(2-) and SO4(2-)) in potassium hydroxide eluents. The adsorbents show the decrease of selectivity with increasing the hydrophilicity of the terminal functional site. The anion exchangers having more flexible and hydrophilic 1,4-BDDGE linker provide smaller separation factors for most of the analytes as compared with RDGE-containing adsorbents with the same terminal ion exchange sites, but are characterized with higher column efficiencies and better peak symmetry for polarizable anions. In case of 1,4-BDDGE-modified anion exchangers of the particle size of 3.3μm functionalized with DMEA and MDEA the calculated values of column efficiencies for polarizable NO3(-) and Br(-) are up to 49,000 and 53,000N/m, respectively, which is almost twice higher than the values obtained for the RDGE-containing analogues. PMID:26159253

  10. 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

    Stevens, F J

    1989-01-01

    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. PMID:2765653

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

    PubMed Central

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

    2012-01-01

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

  12. Characterization of the synthesis of N,N-dimethyltryptamine by reductive amination using gas chromatography ion trap mass spectrometry.

    PubMed

    Brandt, Simon D; Moore, Sharon A; Freeman, Sally; Kanu, Abu B

    2010-07-01

    The present study established an impurity profile of a synthetic route to the hallucinogenic N,N-dimethyltryptamine (DMT). The synthesis was carried out under reductive amination conditions between tryptamine and aqueous formaldehyde in the presence of acetic acid followed by reduction with sodium cyanoborohydride. Analytical characterization of this synthetic route was carried out by gas chromatography ion trap mass spectrometry using electron- and chemical-ionization modes. Methanol was employed as a liquid CI reagent and the impact of stoichiometric modifications on side-products formation was also investigated. Tryptamine 1, DMT 2, 2-methyltetrahydro-β-carboline (2-Me-THBC, 3), N-methyl-N-cyanomethyltryptamine (MCMT, 4), N-methyltryptamine (NMT, 5), 2-cyanomethyl-tetrahydro-β-carboline (2-CM-THBC, 6) and tetrahydro-β-carboline (THBC, 7) have been detected under a variety of conditions. Replacement of formaldehyde solution with paraformaldehyde resulted in incomplete conversion of the starting material whereas a similar replacement of sodium cyanoborohydride with sodium borohydride almost exclusively produced THBC instead of the expected DMT. Compounds 1 to 7 were quantified and the limits of detection were 28.4, 87.7, 21.5, 23.4, 41.1, 36.6, and 34.9 ng mL(-1), respectively. The limits of quantification for compounds 1 to 7 were 32.4, 88.3, 25.4, 24.6, 41.4, 39.9, and 37.0 µg mL(-1), respectively. Linearity was observed in the range of 20.8-980 µg mL(-1) with correlation coefficients > 0.99. The application holds great promise in the area of forensic chemistry where development of reliable analytical methods for the detection, identification, and quantification of DMT are crucial and also in pharmaceutical analysis where DMT might be prepared for use in human clinical studies. PMID:20648523

  13. Insights Into Water-Soluble Organic Aerosol Sources From Carbon-13 Ratios of Size Exclusion Chromatography Fractions

    NASA Astrophysics Data System (ADS)

    Ruehl, C. R.; Chuang, P. Y.; McCarthy, M. D.

    2008-12-01

    Many sources of organic aerosols have been identified and quantified, and much of this work has used individual (mosty water-insoluble) compounds as tracers of primary sources. However, most organic aerosol cannot be molecularly characterized, and the water-soluble organic carbon (WSOC) in many aerosols is thought to originate from gaseous precursors (i.e., it is secondary in nature). It can therefore be difficult to infer aerosol sources, particularly of background (i.e., aged) aerosols, and of the relatively high-MW component of aerosols. The stable isotope ratios (δ13C) of organic aerosols have been used to distinguish between sources, with lighter values (-30‰ to -25‰) interpreted as having originated from fossil fuel combustion and C4 biogenic emission, and heavier values (-25‰ to - 20‰) indicating a marine or C3 biogenic source. Most published measurements were of either total suspended particulates or PM2.5, however, and it is unknown to what extent these fractions differ from submicron WSOC. We report δ13C for submicron WSOC collected at a variety of sites, ranging from marine to polluted to background continental. Bulk marine organic δ13C ranged from -30.4 to - 27.6‰, slightly lighter than previously published results. This could be due to the elimination of supermicron cellular material or other biogenic primary emissions from the sample. Continental WSOC δ13C ranged from -19.1 to -29.8‰, with heavier values (-19.8 ± 1.0‰) in Oklahoma and lighter values at Great Smoky Mountain National Park in Tennessee (-25.8 ± 2.6‰) and Illinois (-24.5 ± 1.0‰). This likely results from the greater proportional of C3 plant material in the Oklahoma samples. In addition to bulk samples, we used size exclusion chromatography (SEC) to report δ13C of organic aerosols as a function of hydrodynamic diameter. Variability and magnitude of hydrodynamic diameter was greatest at low SEC pH, indicative of the acidic character of submicron WSOC. Tennessee aerosols included neutral compounds not observed at other sites, and in general showed more variability in both hydrodynamic diameter and δ13C. This suggests that secondary formation processes were most active at this site.

  14. Size Exclusion Chromatography Studies of the Initial Self-Association Steps of Chicken Egg White Lysozyme Nucleation

    NASA Technical Reports Server (NTRS)

    Ewing, Felecia; Donovan, David; Pusey, Marc

    2000-01-01

    Nucleation is one of the least understood aspects of crystallogenesis. In the case of macromolecule nucleation, this understanding is further hampered by uncertainty over what precisely is being discussed. We define the process of solute self-association (aggregation, oligomerization, interaction, clustering, etc.) whereby n-mers (n > or = 2) having a crystallographic or nascent crystallographic arrangement leading to the critical nucleus reversibly form in the solution, to be part of the nucleation process. This reversible self-association process is a fundamental part of the nucleation process, and occurs as a function of the solute concentration. In the case of chicken egg white lysozyme, a considerable body of experimental evidence leads us to the conclusion that it also forms the crystal growth units. Size exclusion chromatography is a simple and direct method for determining the equilibrium constants for the self-association process. A Pharmacia FPLC system was used to provide accurate solution flow rates. The column, injection valve, and sample loop were all mounted within a temperature-controlled chamber. Chromatographically re-purified lysozyme was first dialyzed against the column equilibration buffer, with injection onto the column after several hours pre-incubation at the running temperature. Preliminary experiments, were carried out using a Toyopearl HW-50F column (1 x 50cm), equilibrated with 0.1 M sodium acetate, 5% sodium chloride, pH 4.6, at 15C. Protein concentrations from 0.1 to 4 mg/ml were employed (C(sub sat) = 1.2 mg/ml). The data from several different protein preparations consistently shows a progressively decreasing elution volume with increasing protein concentration, indicating that reversible self-association is occurring. The dotted line indicates the monomeric lysozyme elution volume. However, lysozyme interacts with the column matrix in these experiments, which complicates data analysis.Accordingly, we are testing silica-based HPLC columns in an effort to eliminate this problem and substantially reduce the column volume and experimental run time. The results and data analysis from these and subsequent experiments will be presented.

  15. [Determination of alditols in foods by ion chromatography-mass spectrometry].

    PubMed

    Zhou, Hongbin; Xiong, Zhiyu; Li, Ping; Li, Jing; Sun, Li; Zhao, Yunxia

    2013-11-01

    A method for the determination of alditols in foods by ion chromatography-mass spectrometry (IC-MS) has been developed. The samples were extracted and cleaned up with the solid phase extraction (SPE). Then, the ion chromatographic separation was performed on a CarboPar MA1 column. The alditols were determined by MS with the selected ion monitoring (SIM) mode and quantified by the external standard method. The calibration curves showed good linearity in the certain ranges with the correlation coefficients (R2) greater than 0.99. The limits of quantification (S/N = 10) of erythritol, xylitol, D-sorbitol, D-mannitol, lactitol, maltitol were 0.98, 1.99, 2.24, 5.92, 13.56, 13.21 mg/kg and the limits of detection (S/N = 3) were 0.28, 0.59, 0.71, 1.74, 4.14, 4.03 mg/kg, respectively. The spiked recoveries of the alditols in the foods at different levels were in the range of 82.5%-108.0% with the relative standard deviations (RSDs) of 1.5%-7.6%. The sensitivity, accuracy and precision of the method meet the technical standards of the determination. The method can be applied to the determination of alditols in foods. PMID:24558846

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

    SciTech Connect

    Niss, N.D.

    1989-07-01

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

  17. Portable, fully autonomous, ion chromatography system for on-site analyses.

    PubMed

    Elkin, Kyle R

    2014-07-25

    The basic operating principles of a portable, fully autonomous, ion chromatography system are described. The system affords the user the ability to collect and analyze samples continuously for 27 days, or about 1930 injections before needing any user intervention. Within the 13 kg system, is a fully computer controlled autosampling, chromatography and data acquisition system. An eluent reflux device (ERD), which integrates eluent suppression and generation in a single multi-chambered device, is used to minimize eluent consumption. During operation, about 1 μL of water per minute is lost to waste while operating standard-bore chromatography at 0.5 mL min(-1) due to eluent refluxing. Over the course of 27 days, about 100mL of rinse water is consumed, effectively eliminating waste production. Data showing the reproducibility (below 1% relative standard deviation over 14 days) of the device is also presented. Chromatographic analyses of common anions (Cl(-), NO3(-), SO4(2-), PO4(3-)), is accomplished in under 15 min using a low backpressure guard column with ∼ 25 mM KOH isocratic elution. For detection, a small capacitively-coupled contactless conductivity detector (C4D) is employed, able to report analytes in the sub to low micromolar range. Preconcentration of the injected samples gives a 50-fold decrease in detection limits, primarily utilized for in-situ detection of phosphate (LOQ 10 μg L(-1)). Field analyses are shown for multiple on-site analyses of stream water indifferent weather conditions. PMID:24913366

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

    PubMed Central

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

    1995-01-01

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

  19. Ion-exchange vs reversed-phase chromatography for separation and determination of basic psychotropic drugs.

    PubMed

    Petruczynik, Anna; Wróblewski, Karol; Deja, Michał; Waksmundzka-Hajnos, Monika

    2015-11-01

    Ion exchange chromatography, an alternative to reversed-phase (RP) chromatography, is described in this paper. We aimed to obtain optimal conditions for the separation of basic drugs because silica-based RP stationary phases show silanol effect and make the analysis of basic analytes hardly possible. The retention, separation selectivity, symmetry of peaks and system efficiency were examined in different eluent systems containing different types of buffers at acidic pH and with the addition of organic modifiers: methanol and acetonitrile. The obtained results reveal a large influence of the salt cation used for buffer preparation and the type of organic modifier on the retention behavior of the analytes. These results were also compared with those obtained on an XBridge C18 column. The obtained results demonstrated that SCX stationary phases can be successfully used as alternatives to C18 stationary phases in the separation of basic compounds. The most selective and efficient chromatographic systems were applied for the quantification of some psychotropic drugs in fortified human serum samples. PMID:25944095

  20. Determination of substituted indole derivatives by ion suppression-reverse-phase high-performance liquid chromatography.

    PubMed

    Frankenberger, W T; Poth, M

    1987-09-01

    A method for the separation of substituted indole derivatives has been developed by the use of ion suppression-reversed-phase high-performance liquid chromatography (IS-HPLC). Signal response, selectivity (alpha), retention times (tR), and capacity factors (k') were monitored by varying the mobile phase with respect to methanol composition and pH. Chromatographic parameters including tR, k', K (distribution coefficients), alpha, number of theoretical plates, height equivalent to theoretical plates, and column resolution were calculated and assessed in regard to the suitability of four stationary phases in the analysis of 20 substituted indole derivatives. This work has established the chromatographic foundation needed to analyze over 10 specific enzyme reactions involved in the microbial and plant metabolism of auxins. Quantitative studies on the stability of auxins were possible by employing IS chromatography (ISC). The application of the developed IS chromatographic technique was employed to detect indole-3-acetic acid derived from L-tryptophan in a fluorescent pseudomonad culture. PMID:3425900

  1. Determination of paraquat in marijuana by reversed-phase paired-ion high performance liquid chromatography.

    PubMed

    Needham, L; Paschal, D; Rollen, Z J; Liddle, J; Bayse, D

    1979-02-01

    A sensitive and selective method is described for the quantitative determination of paraquat in marijuana. Paraquat is extracted from finely ground plant material with hydrochloric acid with sonification, and the resulting acidic solution is extracted with chloroform:isopropanol (9:1) and evaporated to dryness. The residue is reconstituted with aqueous phosphate buffer pH 7.0; the solution is passed through a C-18 SEP-PAK TM and is analyzed with high performance liquid chromatography, using a reversed-phase column and an "ion pairing" reagent in the mobile phase. The recovery of paraquat in laboratory-spiked material varied from 90-97%. Results obtained with confiscated, field-sprayed marijuana by the procedure described were in excellent agreement with those obtained with a well-established ultraviolet procedure. The calculated limit of detection with this method is 2 ng of paraquat. PMID:479338

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

    SciTech Connect

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

    1994-10-01

    A comprehensive ion chromatography (IC) with beta-counting (beta) and inductively coupled plasma mass spectrometry (ICP/MS) detection approach has been developed to separate and detect 20 radionuclides in a Hanford waste tank sample. The IC separation was performed using a multi-functional group (anion/cation) resin and eluents of oxalic acid, diglycolic acid, and hydrochloric acid. Shorter-lived radionuclides were detected by a solid-state beta scintillation counter on-line with the IC separation. Mass spectrometry detection using an efficient and robust plasma ionization source provides isotopic discernability for both stable isotopes and long-lived radioactive species. Effective separation of over 47 elements and 160 isotopes was obtained from a single-elution scheme lasting 70 min. Automated IC separations provide the potential for rapid isotopic and radionuclide analysis of complex radioactive waste, using minimal sample and reagent volumes and reducing personnel exposures.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  4. High-resolution determination of 147Pm in urine using dynamic ion-exchange chromatography.

    PubMed

    Elchuk, S; Lucy, C A; Burns, K I

    1992-10-15

    A procedure has been developed for measuring 147Pm in bioassay samples, based on the separation and preconcentration of 147Pm from the urine matrix by adsorption onto a conventional cation-exchange column with final separation and purification by HPLC using dynamic ion-exchange chromatography. The concentration of 147Pm is determined by collecting the appropriate HPLC fraction and measuring the 147Pm by liquid scintillation counting. The limit of detection is 0.1 Bq (3 fg) 147Pm based on a 500-mL sample of urine and a counting time of 30 min with a background of 100 cpm. Ten samples can be processed in 1.5-2 days. PMID:1466450

  5. Determination of total dissolved inorganic carbon in freshwaters by reagent-free ion chromatography.

    PubMed

    Polesello, Stefano; Tartari, Gabriele; Giacomotti, Paola; Mosello, Rosario; Cavalli, Silvano

    2006-06-16

    Studies of inorganic carbon cycle in natural waters provide important information on the biological productivity and buffer capacity. Determination of total inorganic carbon, alkalinity and dissolved carbon dioxide gives an indication of the balance between photosynthesis and respiration by biota, both within the water column and sediments, and carbon dioxide transfers from the water column to the atmosphere. There are few methods to measure and distinguish the different forms of inorganic carbon, but all require a measure or an indirect quantification of total inorganic carbon. A direct measurement of TIC in water is made possible by the introduction of electrolytic generated hydroxide eluent in ion chromatography which allows to detect a chromatographic peak for carbonate. The advantage of this method is that all the inorganic forms of carbon are converted in carbonate at eluent pH and can be detected as a single peak by conductivity detection. Repeatability of carbonate peak was evaluated at different levels from 0.02 to 6 mequiv.l(-1) both in high purity water and in real samples and ranged from 1 to 9%. The calibration curve was not linear and has to be fitted by a quadratic curve. Limit of detection was estimated to be 0.02 mequiv.l(-1). Accuracy has been estimated by comparing ion chromatography method with total inorganic carbon calculated from alkalinity and pH. The correlation between the two methods was good (R(2)=0.978, n=141). The IC method has been applied to different typologies of surface waters (alpine and subalpine lakes and rivers) characterised by different chemical characteristics (alkalinity from 0.05 to 2 mequiv.l(-1) and pH from 6.7 to 8.5) and low total organic carbon concentrations. This analytical method allowed to describe the distribution of TIC along the water column of two Italian deep lakes. PMID:16620857

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

    SciTech Connect

    Wiedenman, B.; White, T.

    2009-11-16

    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.

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

    SciTech Connect

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

    2011-05-30

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

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

    ERIC Educational Resources Information Center

    Drossman, Howard

    2007-01-01

    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…

  9. 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...

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

    EPA Science Inventory

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

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

    ERIC Educational Resources Information Center

    Drossman, Howard

    2007-01-01

    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

  12. 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...

  13. The application of the high-performance ion-exchange chromatography for the analysis of bovine milk proteins.

    PubMed

    Bican, P

    1985-07-15

    A high-performance ion-exchange chromatographic (HPIEC) method for the analysis of milk proteins is described. The technique provides an alternative to other separation methods. The resolution obtained for both the proteins of the casein group and bovine lactoserum is comparable with that of electrophoretic analysis on polyacrylamide gels and low-pressure chromatography. PMID:4007137

  14. IDENTIFICATION OF MICROCYSTIN TOXINS FROM A STRAIN OF MICROCYSTIS AERUGINOSA BY LIQUID CHROMATOGRAPHY INTRODUCTION INTO A HYBRID LINEAR ION TRAP-FOURIER TRANSFORM ION CYCLOTRON RESONANCE MASS SPECTROMETER

    EPA Science Inventory

    The cyclic heptapeptide microcystin toxins produced by a strain of Microcystis aeruginosa that has not been investigated previously were separated by liquid chromatography and identified by high-accuracy m/z measurements of their [M + H]+ ions and the fragment i...

  15. Probing the metal-homeostatis effects of the administration of chromium(vi) to mice by ICP MS and size-exclusion chromatography-ICP MS.

    PubMed

    Döker, Serhat; Mounicou, Sandra; Doğan, Mehmet; Lobinski, Ryszard

    2010-08-01

    Concentrations of chromium, copper, iron, manganese and zinc were determined in liver, kidney, brain, lung, heart and testis of mouse following intraperitoneal injection of hexavalent chromium [Cr(vi)] at a single dose of 8.0 mg Cr/kg. As result, chromium concentrations increased ca. 40-fold in liver and kidney and by a factor of 3-5 in all the other tissues. The homeostasis of Cu, Fe, Mn and Zn was also affected. The element molecular weight distribution was evaluated in the cytosols of the different mouse organs by size-exclusion chromatography (Superdex-75) with UV-VIS and ICP-MS detection. The administration of Cr(vi) resulted in differences in the elution profiles of Fe, Mn, Cu and Zn-protein complexes. Bioinduced Mn, Fe and Zn-binding proteins could be detected in some tissues, especially in liver and kidney. Different molecular weight fractions containing chromium were heartcut and submitted to tryptic digestion prior to MALDI MS analysis. Cr-peptide complexes could be obtained both in non-denaturing and in denaturing (in the presence of urea and DTT) conditions. They were isolated by size-exclusion chromatography with a smaller separation range (Superdex Peptide) but could not be identified by MALDI MS. PMID:21072339

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

    PubMed

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

    2012-01-27

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

  17. Determination of pyrethroid insecticides in sediment by gas chromatography--ion trap tandem mass spectrometry.

    PubMed

    You, Jing; Wang, Dongli; Lydy, Michael J

    2010-04-15

    A method was developed to analyze 10 pyrethroid insecticides in sediment by gas chromatography-ion trap tandem mass spectrometry (GC-MS/MS) after accelerated solvent extraction and solid phase extraction cleanup. The MS/MS parameters included selection of the precursor and product ions, excitation mode, excitation amplitude and the stability parameter q(z), and were optimized to maximize detection sensitivity. Due to its superior ability to remove background noise, GC-MS/MS showed elevated selectivity and improved confidence in peak identification compared to GC-electron capture detector (ECD). The instrumental detection limits for GC-MS/MS ranged from 148 to 4033 fg, and the calibration curves were linear from 5 to 1000 microg/L for all of the pyrethroids except cyfluthrin. The method detection limits for pyrethroids ranged from 0.10 to 0.80 microg/kg dry sediment, while the recoveries were 59.7-128%, 60.6-90.9% and 63.2-83.6% with the relative standard deviations of 5.3-25.3%, 1.1-10.6% and 3.0-15.6% at the spiking levels of 1, 5 and 20 microg/kg, respectively. Field sediment collected from California was used to validate the newly developed method, and analytical results were comparable to those by GC-ECD in most cases. However, as the result of a cleaner background, more pyrethroids were identified by GC-MS/MS. PMID:20188899

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

    PubMed

    Nowack, B

    1997-06-27

    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

  19. Collection of ethanolamines in air and determination by mobile phase ion chromatography

    SciTech Connect

    Bouyoucos, S.A.; Melcher, R.G.

    1986-03-01

    A method is described for the collection and determination of monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) in air. Samples were collected by pulling air through a glass tube containing alumina, cleaned especially to remove interfering inorganic ions. The ethanolamines were desorbed with water and determined by Mobile Phase Ion Chromatography (MPIC). The recovery and total relative precision for MEA, DEA, and TEA - all collected from air at a flow rate of 100 mL/min for 7 hr - was 93.1 +/- 17%, 92.7 +/- 15% and 89.4 +/- 21%, respectively (95% confidence level). The method was validated for all three compounds from approximately the limit of detection (3 x noise) to ten times the limit of detection. Based on a sample size of 42 L, MEA was validated over the range from 0.12 to 3.0 ppm v/v (TLV=3), DEA over the range from 0.25 to 3.3 ppm v/v (TLV=3) and TEA from 0.31 to 3.7 ppm v/v (no TLV assigned). No effect on recovery was observed when sampling at high humidity or on storage of the samples for up to 31 days.

  20. Device to generate high purity hydroxide solution in-line for ion chromatography.

    PubMed

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

    2016-05-01

    Herein, we report a new device that generates a high-purity hydroxide solution in line. The device's container has three compartments that are isolated from each other by two cation exchange (CE) membranes. In each end of the container, an electrode is installed. The three compartments are filled with ion exchange resins. A bipolar boundary is a composite boundary comprising anion- and cation-exchangers. This device has two bipolar boundaries, which are used to separate the location of hydroxide solution generation from the location where water is electrolyzed. Therefore, it can produce high-purity hydroxide solutions that are free from gases and anionic impurities. The hydroxide solution is generated on the basis of an electrokinetic phenomenon at the surfaces of ion-exchange resins and membranes in an electric field; NaOH concentration can be controlled at rates from 0.01 to 100mM per 1mL/min by adjusting the electrical current (0-200mA) applied to the device. As the generated solution is used as an eluent for a suppressed anion chromatography, the electrical conductivity of the effluent from the suppressor is as low as that of ultra-pure water. Thus, the noise of the base-line electrical conductivity is improved, and so the detection limit of anions on the sub-ng/mL order can be achieved. PMID:27063368

  1. The use of on-line ion chromatography for high temperature and high pressure reaction studies

    SciTech Connect

    Lynch, G.J.

    1993-10-01

    This paper describes the use of on-line ion chromatography as a tool for chemistry reaction studies in small volume systems. The technique was used to study chemistry behavior in a high temperature and high pressure autoclave system. A dual analyzer, multi-channel on-line ion chromatograph (IC) was configured to automate the sampling and analysis. Analytical channels were set up for analysis of inorganic anions, monovalent cations, conductivity, and pH. Conductivity and pH were measured using the IC as a flow injection analyzer. Use of the IC system provides significant advantages over conventional sampling and analysis techniques: Reduction in sample volume, a closed sampling system that protects air or light sensitive analytes from breakdown, around-the-clock test performance combined with automatic calibration and quality control checking, and detection and tracking of reaction products or unexpected contaminants. Methods used to correct measured concentrations for the effects of sampling and for calculation of control chemical loss half-lives are presented. A limited evaluation of the flow injection analysis methods for conductivity and pH is provided.

  2. Ionic content in plant extracts determined by ion chromatography with conductivity detection.

    PubMed

    Cataldi, Tommaso R I; Margiotta, Giovanna; Del Fiore, Antonella; Bufo, Sabino A

    2003-01-01

    A simple method is described for the determination of the ionic content of vegetable samples by ion chromatography with suppressed conductivity detection. Extracts of leaves of cucumber (Cucumis sativus), leaves and cotyledons of watermelon (Citrullus lanantus), cotyledons of zucchini (Cucurbitapepo), and leaves and roots of olive (Olea europaea) obtained at room temperature yielded chromatographic profiles with substantial differences in the relative contents of Cl-, NO3-, HPO4(2-) and SO4(2-) as well as of Na+, NH4+, K+, Mg2+ and Ca2+. Although NO3-, Cl- and K+ were common to each extracted sample and accounted for most of the ions present, two additional anion peaks (i.e. malate and oxalate) were detected. Among the vegetable tissues investigated, olive roots contained a considerable amount of oxalate (37 mg/g dry weight), while Na+, which is present in very low amount in extracted samples of leaves and cotyledons, represented ca. 30% of the cationic content of olive roots. In all the examined tissue extracts, K+ was the main cation (16-55 mg/g dry weight) and NO3-, Cl- and HPO4(2-) were the main inorganic anions. PMID:12793466

  3. Separation of amaranthine-type betacyanins by ion-pair high-speed countercurrent chromatography.

    PubMed

    Jerz, Gerold; Gebers, Nadine; Szot, Dominika; Szaleniec, Maciej; Winterhalter, Peter; Wybraniec, Slawomir

    2014-05-30

    Betacyanins, red-violet plant pigments, were fractionated by ion-pair high-speed countercurrent chromatography (IP-HSCCC) from leaves extract of Iresine lindenii Van Houtte, an ornamental plant of the family Amaranthaceae. An HSCCC solvent system consisting of TBME-1-BuOH-ACN-H2O (1:3:1:5, v/v/v/v) was applied using ion-pair forming heptafluorobutyric acid (HFBA). Significantly different elution profiles of betacyanin diastereomeric pairs (derivatives based on betanidin and isobetanidin) observed in the HSCCC in comparison to HPLC systems indicate a complementarity of both techniques' fractionation capabilities. The numerous diastereomeric pairs can be selectively separated from each other using the HSCCC system simplifying the pigment purification process. Apart from the three well known highly abundant pigments (amaranthine, betanin and iresinin I) together with their isoforms, three new acylated (feruloylated and sinapoylated) betacyanins as well as known pigment hylocerenin (previously isolated from cacti fruits) were characterized in the plant for the first time and they are new for the whole Amaranthaceae family. PMID:24767836

  4. Determination of trace transition metals in environmental matrices by chelation ion chromatography.

    PubMed

    Murgia, Sandro M; Selvaggi, Roberta; Poletti, Antonio

    2011-03-01

    Trace transition metals (Fe(3+), Mn, Cu, Cd, Co, Zn, Ni) in environmental samples were analyzed by chelation ion chromatography using a mixed bed ion-exchange column with pyridine-2,6-dicarboxylic acid (PDCA) and oxalic acid as eluent and large volume direct injection (1,000 ?l). The two eluents, PDCA and oxalic acid, were tested, and repeatability and detection limits were compared. The total analysis time was ~15 min. The separation with PDCA was more successful than that obtained with acid oxalic. It was observed that utilizing PDCA resulted in lower detection limits, higher repeatability, and a quantitative detection of Cd and Mn, which coelute as a single peak when using the oxalic acid. At last, the PDCA calibration graphs resulted linear (r (2)?> 0.999) in the range 0.4-1,000 ?g/L. The procedure was applied to the analysis of metals in soils and in water samples. The results obtained from the analysis of natural waters have demonstrated that the method is simple and efficient, therefore, can be used for the determination of metals in natural waters using a continuous and automatic monitoring system. PMID:20446032

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

    PubMed

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

    2013-03-15

    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

  6. Determination of photodegradation and ozonation by products of linear alkylbenzene sulfonates by liquid chromatography and ion chromatography under controlled laboratory experiments.

    PubMed

    Fernández, J; Riu, J; Garíca-Calvo, E; Rodríguez, A; Fernández-Alba, A R; Barceló, D

    2004-09-01

    A Suntest solar simulator with arc xenon lamp was used to irradiate pure linear alkylbenzene sulfonates (LAS) standard and some commercial LAS solutions. The ozonation treatment was carried out in a pilot plant air-lift type reactor. Kinetic degradation curves were obtained showing an apparent first order reaction in both cases. Extraction and preconcentration of samples was carried out by off-line SPE using polymeric an RP-18 cartridges with recoveries varying from 77 to 93% for the LAS compounds. For LC chromatographic elution of LAS and degradation products an ion pair based on 5mM triethylamine and 5nM acetic acid had to the acetonitrile-water or methanol-water mobile phases. Fluorescence detection was achieved at 225 and 295nm as excitation and emission radiation wavelength, respectively. Degradation by products were identified by liquid chromatography electrospray mass spectrometry detection (LC-ESI-MS). Ion chromatography (IC) was used to analyze refractory species such as oxalate, formate and acetate ions which were present in the treated solution even after 3h of ozone treatment. The LAS mixture was almost totally degraded in less than 20min using O(3)/H(2)O(2), the reaction being faster than in the case of catalyzed photodecomposition. TOC removal reached 84% after 3h of ozonation process. PMID:18969570

  7. A simple liquid extraction protocol for overcoming the ion suppression of triacylglycerols by phospholipids in liquid chromatography mass spectrometry studies.

    PubMed

    Araujo, Pedro; Tilahun, Ephrem; Breivik, Joar Fjørtoft; Abdulkader, Bashir M; Frøyland, Livar; Zeng, Yingxu

    2016-02-01

    It is well-known that triacylglycerol (TAG) ions are suppressed by phospholipid (PL) ions in regiospecific analysis of TAG by mass spectrometry (MS). Hence, it is essential to remove the PL during sample preparation prior to MS analysis. The present article proposes a cost-effective liquid-liquid extraction (LLE) method to remove PL from TAG in different kinds of biological samples by using methanol, hexane and water. High performance thin layer chromatography confirmed the lack of PL in krill oil and salmon liver samples, submitted to the proposed LLE protocol, and liquid chromatography tandem MS confirmed that the identified TAG ions were highly enhanced after implementing the LLE procedure. PMID:26653473

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

    SciTech Connect

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

    2013-09-05

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

  9. High-performance size-exclusion chromatography of /sup 63/Ni-constituents in renal cytosol and microsomes from /sup 63/NiCl/sub 2/-treated rats

    SciTech Connect

    Sunderman, F.W. Jr.; Mangold, B.L.; Wong, S.H.; Shen, S.K.; Reid, M.C.; Jansson, I.

    1983-03-01

    Fractionations of /sup 63/Ni-constituents were performed by high-performance size-exclusion chromatography upon samples of renal cytosol and washed renal microsomes from rats that were killed 1 h after an im injection of /sup 63/NiCl2. Chromatography of renal cytosol on TSK-GEL SW-2000 and SW-3000 separated /sup 63/Ni into six fractions. The largest component (Fraction F) contained approximately 80% of cytosolic /sup 63/Ni. Since Fraction F was eluted near the total permeation volume of SW-2000 columns and beyond the total permeation volume of SW-3000 columns, its molecular weight could not be reliably estimated. The other components, which comprised collectively the remaining 20% of cytosolic /sup 63/Ni, had apparent molecular weights of 168,000 (Fraction A), 84,000 (Fraction B), 51,000 (Fraction C), 24,000 (Fraction D), and approximately 10,000 (Fraction E). Solubilized washed microsomes from kidneys of /sup 63/NiCl2-treated rats contained /sup 63/Ni in five components with elution profiles and /sup 63/Ni-contents that resembled Fractions A, B, D, E, and F of renal cytosol, based upon chromatography on SW-3000 columns. This study provides a rapid, convenient, and reproducible technique to fractionate /sup 63/Ni-components in tissue extracts, and it demonstrates in vivo binding of /sup 63/Ni to several constituents of renal cytosol and microsomes from /sup 63/NiCl2-treated rats.

  10. Determination of perchlorate anion in foods by ion chromatography-tandem mass spectrometry.

    PubMed

    Krynitsky, Alexander J; Niemann, Richard A; Nortrup, David A

    2004-09-15

    A rapid, sensitive, and specific method was developed for determining perchlorate anion in lettuce, cantaloupe, bottled water, and milk. A test portion of chopped crop homogenate was extracted with diluted nitric acid and filtered. Milk proteins were precipitated with acetonitrile, and the supernatant, after centrifugation, was cleaned up on a graphitized carbon solid-phase extraction column. Water samples were analyzed directly. All test solutions were syringe filtered and mixed with an 18O4-labeled perchlorate internal standard before ion chromatography-tandem mass spectrometry. A strong anion exchange column eluted with 100 mM ammonium acetate in 50:50 (v/v) acetonitrile/water was interfaced via electrospray ionization to a triple stage quadrupole mass spectrometer operated in the negative ion mode. The labeled internal standard corrected for any sample matrix effects on measured signals. Four parent-to-product ion transitions, for loss of oxygen, were monitored for native and 18O4-labeled perchlorate anion, respectively: 35Cl-perchlorate, m/z 99 --> 83 and 107 --> 89; 37Cl-perchlorate, m/z 101 --> 85 and 109 --> 91. The limit of quantitation was 1.0 microg/kg in lettuce, 2.0 microg/kg in cantaloupe, 0.50 microg/L in bottled water, and 3.0 microg/L in milk. Native perchlorate was recovered from fortified test portions in the range 93-107% for lettuce, 107-114% for cantaloupe, 100-115% for bottled water, and 99-101% for milk. PMID:15362915

  11. Analysis of VX nerve agent hydrolysis products in wastewater effluents by ion chromatography with amperometric and conductivity detection.

    PubMed

    Piao, Haishan; Marx, Randall B; Schneider, Steven; Irvine, David A; Staton, John

    2005-09-30

    An analytical method, based on the use of ion chromatography, was developed to monitor the levels of three regulated VX hydrolysis products in the effluent from a biological wastewater treatment process--ethylmethylphosphonic acid, methylphosphonic acid and 2-(diisopropyl)aminoethanethiol. Previous methods have not been applied to wastewater matrices or 2-(diisopropyl)aminoethanethiol. Despite the specificity and sensitivity constraints of this method, it was possible to measure the compounds in bioreactor effluents down to a level substantially below the US Army discharge limit of 0.1% (w/v). Analytical data was confirmed by liquid chromatography-mass spectrometry (LC-MS) at an independent laboratory. PMID:16130773

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

    PubMed

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

    2003-05-16

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  14. A method for measuring semi- and non-volatile organic halogens by combustion ion chromatography.

    PubMed

    Miyake, Yuichi; Kato, Mika; Urano, Kohei

    2007-01-12

    Recent studies have shown that various semi- and non-volatile organohalogen compounds are ubiquitous in the environment: these include halogenated dioxins including chlorinated dioxins, other persistent organic pollutants (POPs), brominated flame retardants (BFRs), and perfluorooctane sulfonate (PFOS). However, monitoring and assessment of these compounds by the analyses of individual compounds and their isomers is onerous because of their low environmental concentrations and large number of compounds. In this study, we have developed a new method that is capable of screening and monitoring an array of organohalogen compounds efficiently by combustion ion chromatography (CIC) - the new analyzer that serially connects combustion furnace and ion chromatograph. Analyzer performance was evaluated in terms of its applicability, reproducibility, and sensitivity as limit of detection (LOD). Recoveries of organochlorine, organobromine, and organoiodine compounds by the CIC were between 97 and 105%; those of organofluorine compounds were from 86 to 91%. In all cases, the relative standard deviation of five analyses was 4% or smaller. The analyzer would exhibit good sensitivity for various environmental matrices (e.g., 2.8-31ng-X/g-soil, 1.4-16ng-X/L-water, and 9.2-100ng-X/m3N-gas). The method is fast and can provide information regarding the occurrence of organohalogen compounds within 1 or 2 days after sampling. Applicability of the new method for the assessment of contamination in flue gas and fly ash was also demonstrated. Our results show that the method is efficient to investigate emission sources and areas contaminated by organohalogen compounds. PMID:17109873

  15. 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 ...

  16. Mixing characteristics of mixers in flow analysis. Application to two-dimensional detection in ion chromatography.

    PubMed

    Liao, Hongzhu; Dasgupta, Purnendu K; Srinivasan, Kannan; Liu, Yan

    2015-01-01

    Three mixer designs, a back-flow tee mixer (BT), an end-blocked membrane tee mixer (EMT), and a tubular membrane mixer (TM), were fabricated and compared to three commercially available mixers, Visco-Jet Micro mixer (VJM) and HS binary tee mixer with 2 and 10 ?L volume (HS-2 and HS-10) mixing cartridges. Internal volumes ranged from 8.3 to 20.3 ?L. Performance characteristics were evaluated by the Villermaux-Dushman reaction, noise in baseline conductance upon mixing an electrolyte solution with water, and dispersion/relative dispersion of an injected solute. No single characteristic would uniquely qualify a particular device. In typical postcolumn use when a small reagent flow is added to a principal flow stream using a low-pulsation high-end chromatographic pump, with the worst of these mixers, imperfect mixing accounted for 99.6% of the observed noise. EMT, BT, and TM with asymmetric inlets provided better mixing performances relative to VJM, HS-2, and HS-10 with symmetric inlet ports, especially when the secondary liquid flow rate was much lower than the principal stream-flow rate. Dispersion per unit residence time was singularly large for HS-2. Based on its mixing efficiency and small dispersion, the BT design was found to be the best for practicing postcolumn reaction. As an illustrative application, this was then used to introduce electrogenerated LiOH in a suppressed ion chromatography system to perform sensitive detection of weak acids in a second dimension. PMID:25426864

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

    SciTech Connect

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

    2011-01-30

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

  18. Preparation and chromatographic performance of polymer-based anion exchangers for ion chromatography: A review.

    PubMed

    Zatirakha, A V; Smolenkov, A D; Shpigun, O A

    2016-01-21

    In the last decade the developments in the field of ion chromatography (IC) were aimed at increasing the efficiency, sensitivity and rapidity of analysis, as well as on improving separation selectivity. Since selectivity and efficiency to the large extent depend on the surface chemistry of the stationary phase, the development of novel anion exchangers remains one of the priority tasks in modern IC. The exact chemistry of commercially available resins is not known and not many literature data devoted to the procedures of preparing anion exchangers for IC have become available in the last 10-15 years. However, the knowledge about the surface chemistry of anion exchangers can provide understanding of the trends in selectivity and efficiency changes, as well as help with the choice of the stationary phase type suitable for solving a particular analytical task. The current review is devoted to the methods of preparing anion exchangers based on polystyrene-divinylbenzene (PS-DVB) and ethylvinylbenzene-divinylbenzene (EVB-DVB) for IC of inorganic and small organic anions and is aimed at demonstrating the improvement of their performance over the years, which was brought by the development of the new types of stationary phase architecture. PMID:26724761

  19. The analysis of black powder substitutes containing ascorbic acid by ion chromatography/mass spectrometry.

    PubMed

    Lang, Gui-hua Lisa; Boyle, Katherine M

    2009-11-01

    Black powder substitutes containing ascorbic acid are a group of low explosives that utilize ascorbic acid as the fuel. The analysis of these powders is complicated by the degradation of ascorbic acid which occurs rapidly in solution and may also occur as the powder ages. Aqueous extracts of both intact powders and postblast residues were analyzed by an existing ion chromatography/mass spectrometry (IC/MS) method used at the Bureau of Alcohol, Tobacco, Firearms and Explosives. Results have shown that while ascorbic acid itself is not detected in this method, its diagnostic degradation products (threonic acid, monohydrated diketogulonic acid, and oxalic acid) can be identified. In addition, anions from the inorganic oxidizers (perchlorate and nitrate) and combustion products such as chloride, chlorate, and nitrite, can be identified within the same experiment. While this IC/MS method shows promise, future modifications are necessary because of limitations in identifying threonate in postblast residues, as well as coeluting compounds observed in postblast residues. PMID:19732276

  20. Determination of residual anabolic steroid in meat by gas chromatography-ion trap-mass spectrometer.

    PubMed

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

    2004-10-01

    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 analysis. MS(2) was employed for quantitative measurement. In addition, 2d-estradiol was used as an internal standard. Quantitative determination was based on the ratio of peak area of steroid derivative to peak area of internal standard derivative. Good linearity of each compound, 0.03-1.0mug/ml, was determined. Solvent extraction was used to extract residual anabolic compounds in meat samples and a solid phase extraction (SPE) procedure was utilized for sample cleanup and pre-concentration. The limits of detection of anabolic compounds approximately ranged from 0.1 to 0.4mug/kg. The detection limit was comparable with or better than reported methods and was below the minimum required performance limits (MRPLs) established by the European Community (EC). The application of this newly developed method was demonstrated by analyzing various beef, pork, chicken and several animal internal organ samples from local markets. PMID:18969619

  1. Off-line coupling of multidimensional immunoaffinity chromatography and ion mobility spectrometry: A promising partnership.

    PubMed

    Armenta, Sergio; de la Guardia, Miguel; Abad-Fuentes, Antonio; Abad-Somovilla, Antonio; Esteve-Turrillas, Francesc A

    2015-12-24

    The extreme specificity of immunoaffinity chromatography (IAC) columns coupled to the high sensitivity of ion mobility spectrometry (IMS) measurements makes this combination really useful for rapid, selective, and sensitive determination of a high variety of analytes in different samples. The capabilities of the IAC-IMS coupling have been highlighted under three different scenarios: (i) multiclass residue analysis using a single IAC column, (ii) multiclass residue analysis using stacked IAC columns, and (iii) isomer analysis. In the first case, the determination of three strobilurin fungicides - azoxystrobin, picoxystrobin, and pyraclostrobin - in water and strawberry juice was considered, obtaining limits of quantification (LOQs) from 11 to 63μgL(-1). Recoveries from 96 to 106% for water, and from 67 to 104% for strawberry juice were obtained. In the second case, anilinopyrimidine compounds, including two analytes with similar drift time, were selectively retained in different IAC columns and analyzed after independent elution in commercial wine samples by IMS. LOQ values of 16, 14 and 12μgL(-1) were obtained for pyrimethanil, mepanipyrim, and cyprodinil, respectively. The obtained recoveries for wine samples spiked with 25 and 100μgL(-1) were from 82 to 123%. Additionally, the stacked IAC columns concept was applied to the separation of Z and E isomers of azoxystrobin that were selectively retained in specific IAC columns and quantified by IMS. Recoveries between 91 and 94% were obtained for both isomers in water samples. PMID:26654255

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

    SciTech Connect

    Chadwick, J.L.

    1995-04-01

    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.

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

    SciTech Connect

    Best, D.

    2010-08-04

    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'.

  4. Coupled ion chromatography for the determination of chloride, phosphate and sulphate in concentrated nitric acid.

    PubMed

    Biesaga, Magdalena; Schmidt, Nicole; Seubert, Andreas

    2004-02-13

    A coupled ion chromatography (IC) system was used for the determination of chloride, sulphate and phosphate in high-purity nitric acid. Such a high ionic strength matrix causes a selectivity problem in single IC systems. The first part of the system is used for a pre-separation of the analytes from the nitrate matrix. A specially designed high-capacity anion exchanger with low retention for the analytes and high retention for nitrate was developed. The eluent stream containing the analytes was transferred to the second part of the system via a heart-cut valve and a pre-concentration column. The second system utilizes a high performance anion exchanger and is used to quantify the analytes. Recoveries of the analytes are 80-100% for phosphate, and around 100% for sulphate and chloride. Detection limits for chloride, sulphate and phosphate in concentrated nitric acid (69% w/w) are 0.1, 1 and 5 mg/l, respectively. PMID:14763747

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

    PubMed

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

    2013-01-11

    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

  6. Dimethylamine and ammonia measurements with ion chromatography during the CLOUD4 campaign

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    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.

  7. [Determination of 21 fragrance allergens in toys by gas chromatography-ion trap mass spectrometry].

    PubMed

    Lü, Qing; Zang, Qing; Bai, Hua; Li, Haiyu; Kang, Suyuan; Wang, Chao

    2012-05-01

    A method of gas chromatography-ion trap mass spectrometry (GC-IT-MS) was developed for the determination of 21 fragrance allergens in sticker toys, plush toys and plastic toys. The experimental conditions, such as sample pretreatment conditions, and the analytical conditions of GC-IT-MS, were optimized. The sticker toy samples and plush toy samples were extracted with acetone by ultrasonic wave, and the extracts were separated on an Agilent HP-1 MS column (50 m x 0.2 mm x 0.5 microm), then determined by IT-MS and quantified by external standard method. The plastic toy samples were extracted by the dissolution-precipitation approach, cleaned up with an Envi-carb solid phase extraction column and concentrated by rotary evaporation and nitrogen blowing, then determined by GC-IT-MS and quantified by external standard method. The calibration curves showed good linearity in the range of 0.002-50 mg/L with the correlation coefficients greater than 0.996 8. The limits of quantification (LOQ, S/N > 10) were 0.02-40 mg/kg. The average recoveries of the target compounds spiked in the sample at three concentration levels were in the range of 82.2%-110.8% with the relative standard deviations (RSDs) of 0.6%-10.5%. These results show that this method is accurate and sensitive for the qualitative and quantitative determination of the 21 fragrance allergens in the 3 types of toys. PMID:22934411

  8. Human salivary glucose analysis by high-performance ion-exchange chromatography and pulsed amperometric detection.

    PubMed

    Gough, H; Luke, G A; Beeley, J A; Geddes, D A

    1996-02-01

    The aim of this project was to develop an analytical procedure with the required level of sensitivity for the determination of glucose concentrations in small volumes of unstimulated fasting whole saliva. The technique involves high-performance ion-exchange chromatography at high pH and pulsed amperometric detection. It has a high level of reproducibility, a sensitivity as low as 0.1 mumol/l and requires only 50 microliters samples (sensitivity = 0.002 pmol). Inhibition of glucose metabolism, by procedures such as collection into 0.1% (w/v) sodium fluoride, was shown to be essential if accurate results are to be obtained. Collection on to ice followed by storage at -20 degrees C was shown to be unsuitable and resulted in glucose loss by degradation. There were inter- and intraindividual variations in the glucose concentration in unstimulated mixed saliva (range; 0.02-0.4 mmol/l). The procedure can be used for the analysis of other salivary carbohydrates and for monitoring the clearance of dietary carbohydrates from the mouth. PMID:8712970

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

    PubMed

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

    2000-04-21

    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 in under 6 min in a sample containing in excess of 800 mg l(-1) matrix metals. A detection limit of 35 microg l(-1) Be(II) was found using a post-column reaction involving Chrome Azurol S (CAS), 1 M hexamine and 10 mM EDTA buffered at pH 6. The standard addition curve gave excellent linearity (R2>0.999). The procedure was applied to the determination of trace beryllium in a certified sediment sample. The results obtained compared well with the certified value for beryllium. PMID:10823508

  10. Integrated protein analysis platform based on column switch recycling size exclusion chromatography, microenzymatic reactor and microRPLC-ESI-MS/MS.

    PubMed

    Yuan, Huiming; Zhou, Yuan; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2009-10-30

    An integrated platform with the combination of proteins and peptides separation was established via the unit of on-line proteins digestion, by which proteins were in sequence separated by column switch recycling size exclusion chromatography (csrSEC), on-line digested by an immobilized trypsin microreactor, trapped and desalted by two parallel C8 precolumns, separated by microRPLC with the linear gradient of organic modifier concentration, and identified by ESI-MS/MS. A 6-protein mixture, with Mr ranging from 10 kDa to 80 kDa, was used to evaluate the performance of the integrated platform, and all proteins were identified with sequence coverage over 5.67%. Our experimental results demonstrate that such an integrated platform is of advantages such as good time compatibility, high peak capacity, and facile automation, which might be a promising approach for proteome study. PMID:19541319

  11. Development and qualification of a size exclusion chromatography coupled with multiangle light scattering method for molecular weight determination of unfractionated heparin.

    PubMed

    Beirne, John; Truchan, Hilary; Rao, Lin

    2011-01-01

    The molecular weight of unfractionated heparin was determined by size exclusion chromatography (SEC) coupled with multiangle light scattering (MALS) detection. The SEC/MALS method determines absolute molecular weight directly from the angular dependence of scattered light intensity as a function of concentration and does not rely on molecular weight standards for column calibration. The SEC/MALS method developed at Scientific Protein Laboratories was qualified in terms of specificity, precision, robustness, and accuracy. By eliminating the requirement of well-characterized molecular weight standards derived from heparin, the present procedure represents a clear improvement over the column calibration methods used in molecular weight determination. The SEC/MALS method is suitable for routine quality control of unfractionated heparin. PMID:20838778

  12. Analysis and purification of nucleic acids by ion-pair reversed-phase high-performance liquid chromatography.

    PubMed

    Hecker, K H; Green, S M; Kobayashi, K

    2000-11-20

    Sizing of DNA fragments is a routine analysis traditionally performed on agarose or polyacrylamide gels. Electrophoretic analysis is labor-intensive with only limited potential for automation. Recovery of DNA fragments from gels is cumbersome. We present data on automated, size-based separation of DNA fragments by ion-pair reversed-phase high performance liquid chromatography (IP RP HPLC) - DNA chromatography - on the WAVE DNA Fragment Analysis System with the DNASep cartridge. This system is suitable for accurate and rapid sizing of double-stranded (ds) DNA fragments from 50 to ca. 2000 base pairs (bp). Fluorescently labeled DNA fragments are compatible with the technology. Length-dependent separation of dsDNA fragments is sequence independent and retention times are highly reproducible. The resolving capabilities of DNA chromatography are illustrated by the analysis of multiple DNA size markers. Resolved dsDNA fragments are easily collected and are suitable for downstream applications such as sequencing and cloning. DNA chromatography under denaturing conditions with fluorescently labeled DNA fragments offers a means for the separation and purification of individual strands of dsDNA. Analysis of DNA fragments on the WAVE System is highly automated and requires minimal manual intervention. DNA chromatography offers a reliable and automated alternative to gel electrophoresis for the analysis of DNA fragments. PMID:11086196

  13. Characterization and quantitative amino acids analysis of analgesic peptides in cinobufacini injection by size exclusion chromatography, matrix-assisted laser desorption/ionization time of flight mass spectrometry and gas chromatography mass spectrometry.

    PubMed

    Wu, Xu; Si, Nan; Bo, Gao; Hu, Hao; Yang, Jian; Bian, Baolin; Zhao, Hai Yu; Wang, Hongjie

    2015-01-01

    Cinobufacini injection that comes from the water extract of Bufo bufo gargarizans Cantor skin is widely used for cancer treatment in China. Peptide is one of its major types of constituents, however the biological effects and content of this injection are little reported. In present study, the analgesic effect of peptides was determined and evaluated by in-vivo models. To characterize and quantitatively analyze these peptides, a reliable and efficient method combining size exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with amino acid analysis was developed. The peptides presented as a series of analogs with similar molecular weights mostly ranging from 2 to 8 kDa. The amino acid analysis by gas chromatography mass spectrometry (GC-MS) was developed to determine both free and combined amino acids (FAA and CAA) in cinobufacini injection. This method achieved good linearity (R(2) , 0.9909-0.9999) and low limit of detection and quantification. FAA and CAA samples were efficiently analyzed by modified Phenomenex EZ: faast procedure. For the sample analysis, the method showed good repeatability (relative standard deviation, RSD ≤ 10%). For most FAA and CAA the mean recoveries were >80% with RSD <10%. The GC-MS based method is useful for quality assurance of both FAA and CAA in cinobufacini injection. PMID:24924921

  14. Determination of Sulfur in High-Level Waste Sludge by Inductively Coupled Plasma-Atomic Emission Spectroscopy and Ion Chromatography

    SciTech Connect

    COLEMAN, CJ

    2004-04-22

    Significant differences (approximately 30 percent) have been observed in the sulfur measurements in high-level waste sludge by the Analytical Development Section (ADS) using the inductively coupled plasma-atomic emission spectroscopy (ICP-AES) method compared with the ADS ion chromatography (IC) method. Since the measured concentrations of sulfur in the sludge approached the maximum concentration that can be processed in the DWPF, experiments were performed to determine the source of the differences and assess the true accuracy of sulfur measurements.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  16. Determination of metaldehyde in suspected cases of animal poisoning using gas chromatography-ion trap mass spectrometry.

    PubMed

    Jones, A; Charlton, A

    1999-11-01

    A method was developed to detect the molluscicide metaldehyde in samples of stomach contents for forensic toxicology investigations. Gas chromatography-ion trap mass spectrometry in full-scan mode was used to identify and quantify metaldehyde. The limit of detection based on mass chromatograms for the m/z 89 ion was 3 microg/g. Mean recoveries from six different spiked samples were 74% at 25 microg/g and 94% at 500 microg/g. The relative standard deviation of six replicate determinations of a sample containing 632 microg/g metaldehyde was 7.3%. PMID:10552870

  17. Mechanistic modeling of ion-exchange process chromatography of charge variants of monoclonal antibody products.

    PubMed

    Kumar, Vijesh; Leweke, Samuel; von Lieres, Eric; Rathore, Anurag S

    2015-12-24

    Ion-exchange chromatography (IEX) is universally accepted as the optimal method for achieving process scale separation of charge variants of a monoclonal antibody (mAb) therapeutic. These variants are closely related to the product and a baseline separation is rarely achieved. The general practice is to fractionate the eluate from the IEX column, analyze the fractions and then pool the desired fractions to obtain the targeted composition of variants. This is, however, a very cumbersome and time consuming exercise. A mechanistic model that is capable of simulating the peak profile will be a much more elegant and effective way to make a decision on the pooling strategy. This paper proposes a mechanistic model, based on the general rate model, to predict elution peak profile for separation of the main product from its variants. The proposed approach uses inverse fit of process scale chromatogram for estimation of model parameters using the initial values that are obtained from theoretical correlations. The packed bed column has been modeled along with the chromatographic system consisting of the mixer, tubing and detectors as a series of dispersed plug flow and continuous stirred tank reactors. The model uses loading ranges starting at 25% to a maximum of 70% of the loading capacity and hence is applicable to process scale separations. Langmuir model has been extended to include the effects of salt concentration and temperature on the model parameters. The extended Langmuir model that has been proposed uses one less parameter than the SMA model and this results in a significant ease of estimating the model parameters from inverse fitting. The proposed model has been validated with experimental data and has been shown to successfully predict peak profile for a range of load capacities (15-28mg/mL), gradient lengths (10-30CV), bed heights (6-20cm), and for three different resins with good accuracy (as measured by estimation of residuals). The model has been also validated for a two component mixture consisting of the main mAb product and one of its basic charge variants. The proposed model can be used for optimization and control of preparative scale chromatography for separation of charge variants. PMID:26686559

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

    SciTech Connect

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

    1985-05-01

    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.

  19. Characterization of currently marketed heparin products: reversed-phase ion-pairing liquid chromatography mass spectrometry of heparin digests.

    PubMed

    Brustkern, Adam M; Buhse, Lucinda F; Nasr, Moheb; Al-Hakim, Ali; Keire, David A

    2010-12-01

    Here we report results from the analyses by enzymatic digestion and reversed-phase ion-pairing liquid chromatography mass spectrometry (RPIP-LC-MS) of active pharmaceutical ingredient (API) unfractionated heparins (UFHs) from six different manufacturers and one USP standard sample. We employed a reverse phase ion-pairing chromatography method using a C(18) column and hexylamine as the ion-pairing reagent with acetonitrile gradient elution to separate disaccharides generated from the digestion of the heparins by lyase I and III (E.C. 4.2.2.7 and 4.2.2.8) before introduction into an ion-trap mass spectrometer by an electrospray ionization (ESI) interface. Extracted ion chromatograms (EICs) were used to determine the relative abundance of the disaccharides by mass spectrometry. Eight disaccharides were observed and a similar composition profile was observed from digests of 20 UFH samples. The compositional profile determined from these experiments provides a measure of the norm and range of variation in "good" heparin to which future preparations can be compared. Furthermore, the profile obtained in the RPIP-LC-MS assay is sensitive to the presence of the contaminant, oversulfated chondroitin sulfate A (OSCS), in heparin. PMID:21069966

  20. Size Exclusion High Performance Liquid Chromatography: Re-Discovery of a Rapid and Versatile Method for Clean-Up and Fractionation in Chemical Ecology.

    PubMed

    Sperling, Sergej; Khbandner, Stephan; Engel, Katharina C; Steiger, Sandra; Stkl, Johannes; Ruther, Joachim

    2015-06-01

    Solvent extraction of bioactive molecules from glands, tissues, or whole organisms is a common first step in chemoecological studies. Co-extraction of a surplus of high boiling materials such as triacylglycerides (TAGs) and other lipids with higher molecular weight might hamper the identification of volatile or medium-volatile semiochemicals by high resolution chromatographic and spectroscopic techniques. Therefore, effective clean-up procedures are needed to separate potential semiochemicals from the accompanying materials. Size exclusion high performance liquid chromatography (SE-HPLC), a technique often disregarded by chemoecologists, has proved to be a rapid and efficient clean-up method for complex crude extracts. We demonstrated that TAGs can be baseline separated from typical semiochemicals within less than 10 min on a porous gel stationary phase based on highly cross-linked polystyrene/divinylbenzene. We applied the method as a rapid one-step clean-up procedure for the analysis of juvenile hormone III in insect hemolymph by gas chromatography-mass spectrometry. We furthermore introduced some recent application examples on insect pheromones to demonstrate that SE-HPLC is not only an effective method for the purification of crude extracts, but can as well be used as a first fractionation step for the bioassay-guided identification of behavior modifying natural products. SE-HPLC can be well operated with low-boiling solvents such as dichloromethane, and results in fraction volumes of typically less than one ml, which decreases the danger of losing volatile analytes during subsequent concentration steps. PMID:25943862

  1. Distribution of elements binding to molecules with different molecular weights in aqueous extract of Antarctic krill by size-exclusion chromatography coupled with inductively coupled plasma mass spectrometry.

    PubMed

    Li, Bin; Bergmann, Jan; Lassen, Stephan; Leonhard, Peter; Prange, Andreas

    2005-01-01

    The distribution of silver, arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, selenium and zinc binding to species with different molecular weight in aqueous extract of krill was studied by on-line size-exclusion chromatography (SEC)/inductively coupled plasma mass spectrometry (ICP-MS). The extract was fractionated in three fractions with different molecular weight (MW) ranges (>20,000 relative molecular mass (rel. mol. mass), 2000-20,000 rel. mol. mass and <2000 rel. mol. mass), which were further analyzed by SEC with columns having different optimum fractionation ranges in order to obtain more detailed information about the MW distribution of the elements. Various distribution profiles for the target elements among different MW ranges were observed. The results obtained indicated that manganese, zinc, silver, cadmium and lead species were mostly distributed in the higher MW range (>20,000 rel. mol. mass). In the case of chromium, iron, cobalt, arsenic and selenium, most of them bind to species with lower MW (<2000 rel. mol. mass). Only copper and nickel species was predominantly present in middle MW range (2000-20,000 rel. mol. mass). Further speciation of arsenic compounds in the small MW fraction was carried out with anion exchange chromatography (AEC) coupled with ICP-MS. The results showed that the dominant arsenic species in this fraction is As(III) (63% of extractable arsenic), while As(V) (13%) and two unknown arsenic species (19% and 5%, respectively) are present in lower amounts. PMID:15607711

  2. Characterization and quantification of histidine degradation in therapeutic protein formulations by size exclusion-hydrophilic interaction two dimensional-liquid chromatography with stable-isotope labeling mass spectrometry.

    PubMed

    Wang, Chunlei; Chen, Sike; Brailsford, John A; Yamniuk, Aaron P; Tymiak, Adrienne A; Zhang, Yingru

    2015-12-24

    Two dimensional liquid chromatography (2D-LC) coupling size exclusion (SEC) and hydrophilic interaction chromatography (HILIC) is demonstrated as a useful tool to study polar excipients, such as histidine and its degradant, in protein formulation samples. The SEC-HILIC setup successfully removed interferences from complex sample matrices and enabled accurate mass measurement of the histidine degradation product, which was then determined to be trans-urocanic acid. Because the SEC effluent is a strong solvent for the second dimension HILIC, experimental parameters needed to be carefully chosen, i.e., small transferring loop, fast gradient at high flow rates for the second dimension gradient, in order to mitigate the solvent mismatch and to ensure good peak shapes for HILIC separations. In addition, the generation of trans-urocanic acid was quantified by single heart-cutting SEC-HILIC 2D-LC combined with stable-isotope labeling mass spectrometry. Compared with existing 2D quantification methods, the proposed approach is fast, insensitive to solvent mismatch between dimensions, and tolerant of small retention time shifts in the first dimension. Finally, the first dimension diode array detector was found to be a potential degradation source for photolabile analytes such as trans-urocanic acid. PMID:26674608

  3. Designed synthesis of Graphene @titania @mesoporous silica hybrid material as size-exclusive metal oxide affinity chromatography platform for selective enrichment of endogenous phosphopeptides.

    PubMed

    Yao, Jizong; Sun, Nianrong; Deng, Chunhui; Zhang, Xiangming

    2016-04-01

    In this work, a novel size-exclusive metal oxide affinity chromatography (SE-MOAC) platform was built for phosphoproteome research. The operation for preparing graphene @titania @mesoporous silica nanohybrids (denoted as G@TiO2@mSiO2) was facile and easy to conduct by grafting titania nanoparticles on polydopamine (PD)-covered graphene, following a layer of mesoporous silica was coated on the outermost layer. The G@TiO2@mSiO2 nanohybrids exhibited high sensitivity with a low detection limit of 5amol/μL (a total amount of 1fmol) and high selectivity for phosphopeptides at a mass ratio of phosphopeptides to non-phosphopeptides (1:1000). The size-exclusive capability of the nanohybrids were also demonstrated by enriching the phosphopeptides from the mixture of Bovine Serum Albumin (BSA), α-casein, and β-casein digests with a high mass ratio (β-casein digests: α-casein: BSA, 1:500:500), which was attributed to the large surface area and ordered mesoporous channels. In addition, the G@TiO2@mSiO2 nanohybrids were employed to capture the endogenous phosphopeptides from human serum successfully. PMID:26838411

  4. METHOD 332.0: DETERMINATION OF PERCHLORATE IN DRINKING WATER BY ION CHROMATOGRAPHY WITH SUPPRESSED CONDUCTIVITY AND ELECTROSPRAY IONIZATION MASS SPECTROMETRY

    EPA Science Inventory

    This method is applicable to the identification and quantitation of perchlorate in raw and finished drinking waters. The approach used is ion chromatography with suppressed conductivity and electrospray ionization mass spectrometry (IC-ESI/MS)

  5. 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...

  6. 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...

  7. Ion trace detection algorithm to extract pure ion chromatograms to improve untargeted peak detection quality for liquid chromatography/time-of-flight mass spectrometry-based metabolomics data.

    PubMed

    Wang, San-Yuan; Kuo, Ching-Hua; Tseng, Yufeng J

    2015-03-01

    Able to detect known and unknown metabolites, untargeted metabolomics has shown great potential in identifying novel biomarkers. However, elucidating all possible liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) ion signals in a complex biological sample remains challenging since many ions are not the products of metabolites. Methods of reducing ions not related to metabolites or simply directly detecting metabolite related (pure) ions are important. In this work, we describe PITracer, a novel algorithm that accurately detects the pure ions of a LC/TOF-MS profile to extract pure ion chromatograms and detect chromatographic peaks. PITracer estimates the relative mass difference tolerance of ions and calibrates the mass over charge (m/z) values for peak detection algorithms with an additional option to further mass correction with respect to a user-specified metabolite. PITracer was evaluated using two data sets containing 373 human metabolite standards, including 5 saturated standards considered to be split peaks resultant from huge m/z fluctuation, and 12 urine samples spiked with 50 forensic drugs of varying concentrations. Analysis of these data sets show that PITracer correctly outperformed existing state-of-art algorithm and extracted the pure ion chromatograms of the 5 saturated standards without generating split peaks and detected the forensic drugs with high recall, precision, and F-score and small mass error. PMID:25622715

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

    NASA Technical Reports Server (NTRS)

    Limero, Thomas F.; James, John T.

    1994-01-01

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

  9. An electrospray ionization-ion mobility spectrometer as detector for high- performance liquid chromatography.

    PubMed

    Zühlke, Martin; Riebe, Daniel; Beitz, Toralf; Löhmannsröben, Hans-Gerd; Zenichowski, Karl; Diener, Marc; Linscheid, Michael W

    2015-01-01

    The application of electrospray ionization (ESI) ion mobility (IM) spectrometry on the detection end of a high-performance liquid chromatograph has been a subject of study for some time. So far, this method has been limited to low flow rates or has required splitting of the liquid flow. This work presents a novel concept of an ESI source facilitating the stable operation of the spectrometer at flow rates between 10 μL mn(-1) and 1500 μL min(-1) without flow splitting, advancing the T-cylinder design developed by Kurnin and co-workers. Flow rates eight times faster than previously reported were achieved because of a more efficient dispersion of the liquid at increased electrospray voltages combined with nebulization by a sheath gas. Imaging revealed the spray operation to be in a rotationally symmetric multijet mode. The novel ESI-IM spectrometer tolerates high water contents (≤90%) and electrolyte concentrations up to 10mM, meeting another condition required of high-performance liquid chromatography (HPLC) detectors. Limits of detection of 50 nM for promazine in the positive mode and 1 μM for 1,3-dinitrobenzene in the negative mode were established. Three mixtures of reduced complexity (five surfactants, four neuroleptics, and two isomers) were separated in the millisecond regime in stand-alone operation of the spectrometer. Separations of two more complex mixtures (five neuroleptics and 13 pesticides) demonstrate the application of the spectrometer as an HPLC detector. The examples illustrate the advantages of the spectrometer over the established diode array detector, in terms of additional IM separation of substances not fully separated in the retention time domain as well as identification of substances based on their characteristic Ims. PMID:26307720

  10. A two level hierarchical model of protein retention in ion exchange chromatography.

    PubMed

    Salvalaglio, Matteo; Paloni, Matteo; Guelat, Bertrand; Morbidelli, Massimo; Cavallotti, Carlo

    2015-09-11

    Predicting protein retention in ion exchange chromatography (IEX) from first principles is a fascinating perspective. In this work a two level hierarchical modeling strategy is proposed in order to calculate protein retention factors. Model predictions are tested against experimental data measured for Lysozyme and Chymotrypsinogen A in IEX columns as a function of ionic strength and pH. At the highest level of accuracy Molecular Dynamics (MD) simulations in explicit water are used to determine the interaction free energy between each of the two proteins and the IEX stationary phase for a reference pH and ionic strength. At a lower level of accuracy a linear response model based on an implicit treatment of solvation and adopting a static protein structure is used to calculate interaction free energies for the full range of pHs and ionic strengths considered. A scaling coefficient, determined comparing MD and implicit solvent simulations, is then introduced in order to correct the linear response model for errors induced by the adoption of a static protein structure. The calculated free energies are then used to compute protein retention factors, which can be directly compared with experimental data. The possibility to introduce a third level of accuracy is explored testing the predictions of a semiempirical model. A quantitative agreement between the predicted and measured protein retention factors is obtained using the coupled MD-linear response models, supporting the reliability of the proposed approach. The model allows quantifying the electrostatic, van der Waals, and conformational contributions to the interaction free energies. A good agreement between experiments and model is obtained also using the semiempirical model that, although requiring parameterization over higher level models or experimental data, proves to be useful in order to rapidly determine protein retention factors across wide pH and ionic strength ranges as it is computationally inexpensive. PMID:26278361

  11. Evaluation of some parameters affecting troublesome pesticide analysis in gas chromatography-ion-trap mass spectrometry.

    PubMed

    Przybylski, Cédric; Hommet, Frédéric

    2008-08-01

    Nowadays, multiresidue methods for pesticides monitoring in food commodities are commonly employed. It is also well known that the presence of several compounds from the matrix introduces a bias during the detection and the quantification steps. The so-called matrix effect phenomenon is related to the masking or formation of active sites. In GC, this phenomenon occurs in the injector port, and in the separative system (retention gap and/or analytical column) and also causes ionization potential modification of analytes. The main consequence of matrix effect is an increasing or decreasing analyte signal in the presence of the matrix (real sample) in respect to the same analyte in solvent (standard solution). In standard mixture, pesticides themselves interact with the active present sites among analytical chain from injector to the detector. Some matrix components, sometimes at trace amounts, are inevitably present in analyzed samples even after numerous and diverse clean-up procedures. In this paper, the influence of some analytical parameters on pesticide signal response is explored using gas chromatography with ion-trap mass-selective detection (GC-IT-MS). Moreover, the responses of characteristic troublesome analytes are analyzed in various kinds of matrices. Finally, matrix compound identification is initiated to study analyte-matrix relationship. Sample acidification with 0.1% acetic acid was the most appropriate for the majority of pesticides, while 0.1% formic acid was more suitable for base-sensitive ones (amitraz, imazalil, thiabendazole). Among tested calibration methods, matrix matched calibration provides the best results. In green bean matrix model, a matrix/pesticide ratio of 1/1 induces the best detected signal for almost every investigated analytes. Presence and quantity of some identified matrix co-extracted compounds like sterols could be partially a cause of signal enhancement. PMID:18555259

  12. Comprehensive and Reproducible Phosphopeptide Enrichment Using Iron Immobilized Metal Ion Affinity Chromatography (Fe-IMAC) Columns

    PubMed Central

    Ruprecht, Benjamin; Koch, Heiner; Medard, Guillaume; Mundt, Max; Kuster, Bernhard; Lemeer, Simone

    2015-01-01

    Advances in phosphopeptide enrichment methods enable the identification of thousands of phosphopeptides from complex samples. Current offline enrichment approaches using TiO2, Ti, and Fe immobilized metal ion affinity chromatography (IMAC) material in batch or microtip format are widely used, but they suffer from irreproducibility and compromised selectivity. To address these shortcomings, we revisited the merits of performing phosphopeptide enrichment in an HPLC column format. We found that Fe-IMAC columns enabled the selective, comprehensive, and reproducible enrichment of phosphopeptides out of complex lysates. Column enrichment did not suffer from bead-to-sample ratio issues and scaled linearly from 100 μg to 5 mg of digest. Direct measurements on an Orbitrap Velos mass spectrometer identified >7500 unique phosphopeptides with 90% selectivity and good quantitative reproducibility (median cv of 15%). The number of unique phosphopeptides could be increased to more than 14,000 when the IMAC eluate was subjected to a subsequent hydrophilic strong anion exchange separation. Fe-IMAC columns outperformed Ti-IMAC and TiO2 in batch or tip mode in terms of phosphopeptide identification and intensity. Permutation enrichments of flow-throughs showed that all materials largely bound the same phosphopeptide species, independent of physicochemical characteristics. However, binding capacity and elution efficiency did profoundly differ among the enrichment materials and formats. As a result, the often quoted orthogonality of the materials has to be called into question. Our results strongly suggest that insufficient capacity, inefficient elution, and the stochastic nature of data-dependent acquisition in mass spectrometry are the causes of the experimentally observed complementarity. The Fe-IMAC enrichment workflow using an HPLC format developed here enables rapid and comprehensive phosphoproteome analysis that can be applied to a wide range of biological systems. PMID:25394399

  13. Comprehensive and reproducible phosphopeptide enrichment using iron immobilized metal ion affinity chromatography (Fe-IMAC) columns.

    PubMed

    Ruprecht, Benjamin; Koch, Heiner; Medard, Guillaume; Mundt, Max; Kuster, Bernhard; Lemeer, Simone

    2015-01-01

    Advances in phosphopeptide enrichment methods enable the identification of thousands of phosphopeptides from complex samples. Current offline enrichment approaches using TiO(2), Ti, and Fe immobilized metal ion affinity chromatography (IMAC) material in batch or microtip format are widely used, but they suffer from irreproducibility and compromised selectivity. To address these shortcomings, we revisited the merits of performing phosphopeptide enrichment in an HPLC column format. We found that Fe-IMAC columns enabled the selective, comprehensive, and reproducible enrichment of phosphopeptides out of complex lysates. Column enrichment did not suffer from bead-to-sample ratio issues and scaled linearly from 100 ?g to 5 mg of digest. Direct measurements on an Orbitrap Velos mass spectrometer identified >7500 unique phosphopeptides with 90% selectivity and good quantitative reproducibility (median cv of 15%). The number of unique phosphopeptides could be increased to more than 14,000 when the IMAC eluate was subjected to a subsequent hydrophilic strong anion exchange separation. Fe-IMAC columns outperformed Ti-IMAC and TiO(2) in batch or tip mode in terms of phosphopeptide identification and intensity. Permutation enrichments of flow-throughs showed that all materials largely bound the same phosphopeptide species, independent of physicochemical characteristics. However, binding capacity and elution efficiency did profoundly differ among the enrichment materials and formats. As a result, the often quoted orthogonality of the materials has to be called into question. Our results strongly suggest that insufficient capacity, inefficient elution, and the stochastic nature of data-dependent acquisition in mass spectrometry are the causes of the experimentally observed complementarity. The Fe-IMAC enrichment workflow using an HPLC format developed here enables rapid and comprehensive phosphoproteome analysis that can be applied to a wide range of biological systems. PMID:25394399

  14. Method for the determination of ammonium in cigarette tobacco using ion chromatography.

    PubMed

    Watson, Christina Vaughan; Valentin-Blasini, Liza; Damian, Maria; Watson, Clifford H

    2015-07-01

    Ammonia and other alkaline substances have been postulated to be important in cigarette design. The most significant potential contribution of ammonia is a possible interaction with the native, protonated nicotine in the smoke. Ammonia is more alkaline than nicotine and could facilitate a shift in the acid/base equilibrium where a fraction of the total nicotine converts to the more lipophilic, non-protonated form. This non-protonated, or free-base, form of nicotine absorbs more efficiently across membranes, resulting in more rapid delivery to the smoker's bloodstream. Ammonia and other potential ammonia sources, such as additives like diammonium phosphate, could influence the acid-base dynamics in cigarette smoke and ultimately the rate of nicotine delivery. To examine and characterize the ammonia content in modern cigarettes, we developed a fast, simple and reliable ion chromatography based method to measure extractable ammonia levels in cigarette filler. This approach has minimal sample preparation and short run times to achieve high sample throughput. We quantified ammonia levels in tobacco filler from 34 non-mentholated cigarette brands from 3 manufacturers to examine the ranges found across a convenience sampling of popular, commercially available domestic brands and present figures of analytical merit here. Ammonia levels ranged from approximately 0.9 to 2.4mg per gram of cigarette filler between brands and statistically significance differences were observed between brands and manufacturers. Our findings suggest that ammonia levels vary by brand and manufacturer; thus in domestic cigarettes ammonia could be considered a significant design feature because of the potential influence on smoke chemistry. PMID:25934256

  15. Solid-phase microextraction gas chromatography/ion trap mass spectrometry and multistage mass spectrometry experiments in the characterization of germacrene D.

    PubMed

    Gioacchini, A M; Menotta, M; Polidori, E; Giomaro, G; Stocchi, V

    2002-12-01

    Germacrene D is a vegetable pheromone utilized in interactions among organisms belonging to different species. For the first time, using solid-phase microextraction/gas chromatography/ion trap mass spectrometry, the presence of this compound was detected in an in vitro mycorrhizal synthesis system where the mycelium of the ectomycorrhizal fungus Tuber borchii Vittad. interacts with the plant Tilia Americana L. From this symbiosis, a new structure, called ectomycorrhiza, is formed where the two symbionts exchange nutrients and metabolites. It seems that only after this interaction can the mycelium develop the fruitbody, commonly known as truffle. The results obtained allowed us to ascertain that germacrene D was synthesized by the plant exclusively in the presence of T. borchii. The originality of these data prompted us to hypothesize that this compound could be involved in the first step of ectomycorrhiza formation, as it is able to stimulate specific fungi receptors. In fact, plants release hundreds of secondary metabolites that are important in their interactions with other organisms. PMID:12489082

  16. Simultaneous and sensitive analysis of aliphatic carboxylic acids by ion-chromatography using on-line complexation with copper(II) ion.

    PubMed

    Kemmei, Tomoko; Kodama, Shuji; Yamamoto, Atsushi; Inoue, Yoshinori; Hayakawa, Kazuichi

    2015-01-01

    A new approach to ion chromatography is proposed to improve the UV detection of aliphatic carboxylic acids separated by anion-exchange chromatography. When copper(II) ion added to the mobile phase, it forms complexes with carboxylic acids that can be detected at 240 nm. The absorbance was found to increase with increasing copper(II) ion concentration. The retention times of α-hydroxy acids were also found to depend on the copper(II) ion concentration. Addition of acetonitrile to the mobile phase improved the separation of aliphatic carboxylic acids. The detection limits of the examined carboxylic acids (formate, glycolate, acetate, lactate, propionate, 3-hydroxypropionate, n-butyrate, isobutyrate, n-valerate, isovalerate, n-caproate) calculated at S/N=3 ranged from 0.06 to 3 μM. The detector signal was linear over three orders of magnitude of carboxylic acid concentration. The proposed method was successfully applied to analyze aliphatic carboxylic acids in rainwater and bread. PMID:25523885

  17. Boosting Sensitivity in Liquid Chromatography-Fourier Transform Ion Cyclotron Resonance-Tandem Mass Spectrometry for Product Ion Analysis of Monoterpene Indole Alkaloids.

    PubMed

    Nakabayashi, Ryo; Tsugawa, Hiroshi; Kitajima, Mariko; Takayama, Hiromitsu; Saito, Kazuki

    2015-01-01

    In metabolomics, the analysis of product ions in tandem mass spectrometry (MS/MS) is noteworthy to chemically assign structural information. However, the development of relevant analytical methods are less advanced. Here, we developed a method to boost sensitivity in liquid chromatography-Fourier transform ion cyclotron resonance-tandem mass spectrometry analysis (MS/MS boost analysis). To verify the MS/MS boost analysis, both quercetin and uniformly labeled (13)C quercetin were analyzed, revealing that the origin of the product ions is not the instrument, but the analyzed compounds resulting in sensitive product ions. Next, we applied this method to the analysis of monoterpene indole alkaloids (MIAs). The comparative analyses of MIAs having indole basic skeleton (ajmalicine, catharanthine, hirsuteine, and hirsutine) and oxindole skeleton (formosanine, isoformosanine, pteropodine, isopteropodine, rhynchophylline, isorhynchophylline, and mitraphylline) identified 86 and 73 common monoisotopic ions, respectively. The comparative analyses of the three pairs of stereoisomers showed more than 170 common monoisotopic ions in each pair. This method was also applied to the targeted analysis of MIAs in Catharanthus roseus and Uncaria rhynchophylla to profile indole and oxindole compounds using the product ions. This analysis is suitable for chemically assigning features of the metabolite groups, which contributes to targeted metabolome analysis. PMID:26734034

  18. Quantitative In Silico Analysis of Retention of Phenylthiohydantoin-Amino Acids in Reversed-Phase Ion-Pair Liquid Chromatography.

    PubMed

    Hanai, Toshihiko

    2016-04-01

    The retention mechanisms of phenylthiohydantoin (PTH)-amino acids in reversed-phase ion-pair liquid chromatography were quantitatively analyzed in silico. The most significant interaction for the retention was the Lewis acid-base interaction between an aromatic ring of a PTH-amino acid and a hydroxyl-group hydrogen of tetra-alkyl ammonium hydroxide. Solvent effects, addition of molecular interaction (MI) energy values between an analyte and solvent molecules, significantly improved the relationship between the MI energy values, calculated using a molecular mechanics program, and logk values, measured via chromatography. The correlation coefficient between the calculated MI energy values and the logk values was 0.98 (n = 19). PMID:26769717

  19. An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.

    PubMed

    Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

    2015-07-01

    Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt. PMID:25452581

  20. Combining voltammetry and ion chromatography: application to the selective reduction of nitrate on Pt and PtSn electrodes.

    PubMed

    Yang, Jian; Kwon, Youngkook; Duca, Matteo; Koper, Marc T M

    2013-08-20

    To overcome the shortcomings of electroanalytical methods in analyzing the ionic reaction products that are either electrochemically inert or lack distinct electrochemical/spectroscopic fingerprints, we suggest combining voltammetry with ion chromatography by applying online sample collection to the electrochemical cell and offline ion chromatographic analysis. This combination allows a quantitative analysis including the potential dependence of the product distribution in a straightforward way. As a proof-of-concept example, we discuss the formation of ionic reaction products from nitrate reduction on Pt and Sn-modified Pt electrode in acid. On the Pt electrode, ammonia was the only identifiable product. After Sn modification of the Pt electrode, a change in selectivity was observed to hydroxylamine as the dominant product. Moreover, the rate determining step of nitrate reduction (reduction to nitrite) was enhanced by Sn modification of the Pt electrode, and a significant concentration of nitrite was evidenced on a Pt electrode with a high coverage of Sn species. The suggested combination of voltammetry and online ion chromatography hence proves very useful in the quantitative elucidation of electrocatalytic reactions with different ionic products. PMID:23899010

  1. Separation of Metal Complexes with Counter Ions by Tube Radial Distribution Chromatography Using a Ternary Solvent Containing 8-quinolinol.

    PubMed

    Kawai, Yuji; Fujinaga, Satoshi; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2015-01-01

    An open-tubular capillary chromatography system (tube radial distribution chromatography, TRDC) was developed using a ternary solvent (water-acetonitrile-ethyl acetate; volume ratio, 3:8:4) containing 10 mmol L(-1) 8-quinolinol for the separation of nitrate, chloride, and sulfate compounds of Ni(II), Al(III), and Fe(III). When a mixed solution of the Ni(II) compounds was injected into an untreated fused-silica capillary tube (90 cm × 75 μm i.d.) with a ternary solvent flow rate of 0.8 μL min(-1), the compounds were eluted in the following order: [Ni(II)-(8-quinolinol)3] complex, [Ni(II)-(8-quinolinol)]-nitrate ion interaction complex, [Ni(II)-(8-quinolinol)]-chloride ion interaction complex, and [Ni(II)-(8-quinolinol)]-sulfate ion interaction complex. The elution of mixtures of the Al(III) and Fe(III) compounds showed similar trends. PMID:26561263

  2. Size exclusion chromatography for the unambiguous detection of aliphatics in fractions from petroleum vacuum residues, coal liquids, and standard materials, in the presence of aromatics

    SciTech Connect

    Eiman M. Al-Muhareb; Fatma Karaca; Trevor J. Morgan; Alan A. Herod; Ian D. Bull; Rafael Kandiyoti

    2006-05-15

    A method has been developed using size exclusion chromatography (SEC) in heptane eluent that can detect aliphatics unambiguously without fractionation to remove aromatics. Spherical molecules such as colloidal silicas elute at the exclusion limit, while alkanes up to C{sub 50} elute through the porosity of the column. Detection of aliphatics was defined by use of an evaporative light scattering (ELS) detector with the simultaneous absence of UV absorbance at 300 nm. Alkanes smaller than C{sub 12} were not detected because the conditions of operation of the ELS caused their evaporation. All aromatics eluted after the permeation limit of about 25 min and were not detected until well after 45 min by their UV absorbance. The SEC method was applied to petroleum vacuum residues and coal liquids, and their fractions were soluble in pentane or heptane. High-temperature (HT) GC-MS confirmed the presence of alkanes in the pentane- and heptane-soluble fractions of petroleum vacuum residues, but did not elute any of the aromatics known to be present from SEC. Alkanes were examined in pentane-soluble fractions of a coal digest and a low-temperature coal tar; alkanes up to C{sub 40} were detected in the low-temperature tar and, although present in the digest, were masked by aromatics. No alkanes were detected by either SEC or HT GC-MS in fractions from a coal tar pitch. Aromatics in coal liquids and one petroleum residue were also examined by SEC using NMP as eluent and by UV fluorescence spectroscopy. The SEC method will find application to pentane- and heptane-soluble fractions of petroleum liquids and coal liquids where the alkanes are concentrated relative to the more abundant aromatics. 43 refs., 10 figs., 2 tabs.

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

    PubMed

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

    2006-06-16

    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

  4. Separation of membrane-embedded tryptic peptides of Na,K-ATPase by size-exclusion chromatography.

    PubMed

    Tal, D M; Goldshleger, R; Karlish, S J

    1993-08-27

    Several attempts to separate hydrophobic tryptic and cyanogen bromide-digested short peptides from Na,K-ATPase, using HPLC and different acid-organic solvent gradients, failed because of the insolubility of the peptides in the initial or final solvents of the gradients used for elution. Therefore, we opted to use a detergent-containing mobile phase. For sodium dodecyl sulphate-solubilized tryptic peptides of M(r) 7 x 10(3)-100 x 10(3), elution on a TSK-G3000SW size-exclusion column successfully separates families of peptides with a resolution of M(r) 5 x 10(3)-10 x 10(3). Peptides in these size ranges can then be resolved completely by tricine-sodium dodecyl sulphate gel electrophoresis, and identified by microsequencing after transfer to polyvinylidene difluoride paper. For separation of smaller peptides a Biosep-SEC-S2000 column, eluted at slow flow-rates, was evaluated. Use of ammonium chloride buffer allows sensitive detection at 214 nm. The separated fractions are resolved and identified on 16.5% tricine gels. Reasonable resolution has been obtained with defined cyanogen bromide fragments of myoglobin. Resolution of small tryptic and cyanogen bromide fragments of Na,K-ATPase is less successful, but the experiments suggest ways of improving the resolution of peptides in the range M(r) 2 x 10(3)-10 x 10(3). PMID:8408423

  5. Broad-Spectrum Drug Screening Using Liquid Chromatography-Hybrid Triple-Quadrupole Linear Ion Trap Mass Spectrometry.

    PubMed

    Stone, Judy

    2016-01-01

    Urine is processed with a simple C18 solid-phase extraction (SPE) and reconstituted in mobile phase. The liquid chromatography system (LC) injects 10 μL of extracted sample onto a reverse-phase LC column for gradient analysis with ammonium formate/acetonitrile mobile phases. Drugs in the column eluent become charged in the ion source using positive electrospray ionization (ESI). Pseudomolecular ions (M + H) are analyzed by a hybrid triple-quadrupole linear ion trap (QqQ and QqLIT) mass spectrometer using an SRM-IDA-EPI acquisition. An initial 125 compound selected ion monitoring (SRM) survey scan (triple quadrupole or QqQ mode) is processed by the information-dependent acquisition (IDA) algorithm. The IDA algorithm selects SRM signals from the survey scan with a peak height above the threshold (the three most abundant SRM signals above 1000 cps) to define precursor ions for subsequent dependent scanning. In the dependent QqLIT scan(s), selected precursor ion(s) are passed through the first quadrupole (Q1), fragmented with three different collision energies in the collision cell (Q2 or q), and product ions are collected in the third quadrupole (Q3), now operating as a linear ion trap (LIT). The ions are scanned out of the LIT in a mass dependent manner to produce a full-scan product ion spectrum (m/z 50-700) defined as an Enhanced (meaning acquired in LIT mode) Product Ion (EPI) spectrum (Mueller et al., Rapid Commun Mass Spectrom 19:1332-1338, 2005). Each EPI spectrum is linked to its precursor ion and to the associated SRM peak from the survey scan. EPI spectra are automatically searched against a 125 drug library of reference EPI spectra for identification. When the duty cycle is complete (one survey scan of 125 SRMs plus 0-3 dependent IDA-EPI scans) the mass spectrometer begins another survey scan of the 125 SRMs. PMID:26660183

  6. Peptide profiling of Internet-obtained Cerebrolysin using high performance liquid chromatography - electrospray ionization ion trap and ultra high performance liquid chromatography - ion mobility - quadrupole time of flight mass spectrometry.

    PubMed

    Gevaert, Bert; D'Hondt, Matthias; Bracke, Nathalie; Yao, Han; Wynendaele, Evelien; Vissers, Johannes Petrus Cornelis; De Cecco, Martin; Claereboudt, Jan; De Spiegeleer, Bart

    2015-09-01

    Cerebrolysin, a parenteral peptide preparation produced by controlled digestion of porcine brain proteins, is an approved nootropic medicine in some countries. However, it is also easily and globally available on the Internet. Nevertheless, until now, its exact chemical composition was unknown. Using high performance liquid chromatography (HPLC) coupled to ion trap and ultra high performance liquid chromatography (UHPLC) coupled to quadrupole-ion mobility-time-of-flight mass spectrometry (Q-IM-TOF MS), combined with UniProt pig protein database search and PEAKS de novo sequencing, we identified 638 unique peptides in an Internet-obtained Cerebrolysin sample. The main components in this sample originate from tubulin alpha- and beta-chain, actin, and myelin basic protein. No fragments of known neurotrophic factors like glial cell-derived neurotrophic factor (GDNF), neurotrophin nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and ciliary neurotrophic factor (CNTF) were found, suggesting that the activities reported in the literature are likely the result of new, hitherto unknown cryptic peptides with nootropic properties. PMID:26017115

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

    SciTech Connect

    Ford, Michael J; Van Berkel, Gary J

    2004-01-01

    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.

  8. The Effects of Light-Accelerated Degradation on the Aggregation of Marketed Therapeutic Monoclonal Antibodies Evaluated by Size-Exclusion Chromatography With Diode Array Detection.

    PubMed

    Hernández-Jiménez, José; Salmerón-García, Antonio; Cabeza, José; Vélez, Celia; Capitán-Vallvey, Luis Fermín; Navas, Natalia

    2016-04-01

    Research into the effects that exposure to light can have on therapeutic proteins is essential for ensuring the quality and safety of the medicines in which they are used. It is important to understand the effects of light on aggregation to help avoid undesirable colloidal instabilities, both in the original medicines and in the formats in which they are finally administered. In this study, 5 marketed therapeutic mAbs, namely bevacizumab, cetuximab, infliximab, rituximab, and trastuzumab, were investigated for this purpose. The medicines and 2 diluted preparations in 0.9 NaCl (2 mg/mL and 5 mg/mL)-commonly used in clinical practice-were subjected to controlled light-accelerated degradation. The formation of aggregates was monitored by size-exclusion chromatography. The results indicated that light induced protein aggregation. This process of protein damage was influenced above all by mAb concentration, although the particular characteristics of each mAb were also important. Photodegradation also produced the fragmentation of the mAbs. The damage caused to the mAbs as a result of light-induced aggregation and/or fragmentation was demonstrated both in the medicines and in the diluted preparation forms. These findings should be carefully considered when handling the medicines for administration and when recommending beyond-use dates in normal hospital conditions. PMID:26952878

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

    PubMed

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

    2012-05-01

    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 β-lactoglobulin (β-lg), α-lactalbumin (α-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 α-la and β-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

  10. Pre-study and in-study validation of a size-exclusion chromatography method with different detection modes for the analysis of monoclonal antibody aggregates.

    PubMed

    Oliva, Alexis; Fariña, Jose B; Llabrés, Matías

    2016-06-01

    Size exclusion chromatography (SEC) with different detection modes was assessed as a means to characterize the type of bevacizumab aggregate that forms under thermal stress, quantitatively monitoring the aggregation kinetics. The combination of SEC with light-scattering (SEC/LS) detection was validated using in-study validation process. This was performed by applying a strategy based on a control chart to monitor the process parameters and by inserting quality control samples in routine runs. The SEC coupled with a differential refractive-index detector (SEC/RI) was validated using a pre-study validation process in accordance with the ICH-Q2 (R1) guidelines and in-study monitoring in accordance with the Analytical Target Profile (ATP) criteria. The total error and β-expectation tolerance interval rules were used to assess method suitability and control the risk of incorrectly accepting unsuitable analytical methods. The aggregation kinetics data were interpreted using a modified Lumry-Eyring model. The true order of the reaction was determined using the initial-rate approach. All the kinetic data show a linear Arrhenius dependence within the studied temperature range. The Arrhenius approach over-predicted the aggregation rate for 5°C, but provides an idea of the aggregation process and amount of aggregate formed. In any case, real-time stability data are necessary to establish the product shelf-life. PMID:27107247

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

    PubMed

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

    1999-09-01

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

  12. Purification of recombinant virus-like particles of porcine circovirus type 2 capsid protein using ion-exchange monolith chromatography.

    PubMed

    Zaveckas, Mindaugas; Snipaitis, Simas; Pesliakas, Henrikas; Nainys, Juozas; Gedvilaite, Alma

    2015-06-01

    Diseases associated with porcine circovirus type 2 (PCV2) infection are having a severe economic impact on swine-producing countries. The PCV2 capsid (Cap) protein expressed in eukaryotic systems self-assemble into virus-like particles (VLPs) which can serve as antigens for diagnostics or/and as vaccine candidates. In this work, conventional adsorbents as well as a monolithic support with large pore sizes were examined for the chromatographic purification of PCV2 Cap VLPs from clarified yeast lysate. Q Sepharose XL was used for the initial separation of VLPs from residual host nucleic acids and some host cell proteins. For the further purification of PCV2 Cap VLPs, SP Sepharose XL, Heparin Sepharose CL-6B and CIMmultus SO3 monolith were tested. VLPs were not retained on SP Sepharose XL. The purity of VLPs after chromatography on Heparin Sepharose CL-6B was only 4-7% and the recovery of VLPs was 5-7%. Using ion-exchange chromatography on the CIMmultus SO3 monolith, PCV2 Cap VLPs with the purity of about 40% were obtained. The recovery of VLPs after chromatography on the CIMmultus SO3 monolith was 15-18%. The self-assembly of purified PCV2 Cap protein into VLPs was confirmed by electron microscopy. Two-step chromatographic purification procedure of PCV2 Cap VLPs from yeast lysate was developed using Q Sepharose XL and cation-exchange CIMmultus SO3 monolith. PMID:25910233

  13. Analysis of 40 weight loss compounds adulterated in health supplements by liquid chromatography quadrupole linear ion trap mass spectrometry.

    PubMed

    Zeng, Yun; Xu, Yimin; Kee, Chee-Leong; Low, Min-Yong; Ge, Xiaowei

    2016-03-01

    In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) with scheduled multiple reaction monitoring (MRM) enhanced product ion (EPI) method was developed for simultaneous determination of 40 compounds with weight loss effect, including bisacodyl, phenolphthalein, and sibutramine and its metabolites, etc. They might be adulterated in health supplements to get prominent weight loss effect. The samples were analyzed using a Q-Trap 5500 coupled with high performance liquid chromatography (HPLC) and a CORTECS ultra performance liquid chromatography (UPLC) C18 column (100 mm x 2.1 mm x1.6 µm). Scheduled MRM was used as survey scan, MS2 spectra acquired in the EPI mode were used to perform library searching to increase the confidence of detection. Limits of detection were less than 10 ng/g for the majority of the analytes. A total of 447 weight loss products were tested in our laboratory in the past three years. Among these samples, 119 samples were found to be adulterated with one or more weight loss compounds, including sibutramine, its metabolites benzyl sibutramine and desmethyl sibutramine; phenolphthalein; bisacodyl; furosemide; liothyronine (T3); and thyroxine (T4). Copyright © 2015 John Wiley & Sons, Ltd. PMID:26305055

  14. Identification of nitroaromatics in diesel exhaust particulate using gas chromatography/negative ion chemical ionization mass spectrometry and other techniques

    SciTech Connect

    Newton, D.L.; Erickson, M.D.; Tomer, K.B.; Pellizzari, E.D.; Gentry, P.

    1982-04-01

    A series of nitroaromatic compounds were identified in diesel exhaust particulate extract. Isomers of nitroanthracene (and/or nitrophenanthrene) and nitropyrene (and/or nitrofluoranthene) were unequivocally identified. Alkyl homologues of nitroanthracene through C/sub 3/-alkyl-nitroanthracene were tentatively identified. In addition, a C/sub 18/H/sub 11/NO/sub 2/ isomer was tentatively identified. The nitro-substituted polynuclear aromatic hydrocarbons (PAHs) were found in two fractions of diesel exhaust particulate extract collected from a low-pressure liquid chromatography (LPLC) column. One of the two fractions containing nitroaromatic constitutents accounted for a large percentage of the mutagenicity of the crude particulate extract. Initial identification were made by using high-resolution gas chromatography/electron impact mass spectrometry/computer (GC/EIMS) and negative ion chemical ionization mass specrometry/computer (GC/NICIMS). These identifications were confirmed by direct probe high-resolution mass spectrometry (HRMS) and gas chromatography/Fourier transform infrared spectrometry (GC/FT IR). The relative merit of each analytical technique for the determination of nitroaromatics is discussed with emphasis on the usefulness of GC/NICIMS as a means of analyzing for nitro-substituted PAHs.

  15. Determination of clenbuterol in bovine plasma and tissues by gas chromatography-negative-ion chemical ionization mass spectrometry.

    PubMed

    Girault, J; Fourtillan, J B

    1990-09-28

    A highly sensitive and specific assay was developed for the determination of clenbuterol in bovine plasma and tissues. Clenbuterol and the internal standard [2H9]clenbuterol were measured by gas chromatography-negative-ion chemical ionization mass spectrometry with methane as the reagent gas. Bovine tissues including muscle, liver, heart, kidney, lung, suet, brain, spinal cord and thymus were ground in a buffer of pH 7 and then extracted using ethyl acetate. After two subsequent purification steps, the cleaned-up organic extract was derivatized with pentafluoropropionic anhydride. The mass spectrometer was set to monitor the abundant ions m/z 368 and 377 of the perfluoroacyl derivatives. This assay was performed with 1 ml of plasma or 0.2 g of tissue. The feasibility of this method was demonstrated by the determination of clenbuterol residues as the femtomole level in a variety of tissues. PMID:2258412

  16. Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography.

    PubMed

    Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

    2015-03-01

    A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55μg/L, the relative standard deviation (n=10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples. PMID:25523043

  17. Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography

    NASA Astrophysics Data System (ADS)

    Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

    2015-03-01

    A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515 nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0 mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55 μg/L, the relative standard deviation (n = 10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5 mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1 h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples.

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

    PubMed Central

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

    2013-01-01

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

  19. Ion and gas chromatography mass spectrometry investigations of organophosphates in lithium ion battery electrolytes by electrochemical aging at elevated cathode potentials

    NASA Astrophysics Data System (ADS)

    Weber, Waldemar; Wagner, Ralf; Streipert, Benjamin; Kraft, Vadim; Winter, Martin; Nowak, Sascha

    2016-02-01

    The electrochemical aging of commercial non-aqueous lithium hexafluorophosphate (LiPF6)/organic carbonate solvent based lithium ion battery electrolyte has been investigated in view of the formation of ionic and non-ionic alkylated phosphates. Subject was a solvent mixture of ethylene carbonate/ethyl methyl carbonate EC:EMC (1:1, by wt.) with 1 M LiPF6 (LP50 Selectilyte™, BASF). The analysis was carried out by ion chromatography coupled with electrospray ionization mass spectrometry (ESI-MS) for ionic compounds and (headspace) gas chromatography mass spectrometry ((HS)-GC-MS) for non-ionic compounds. The electrochemical aging was performed by galvanostatic charge/discharge cycling and potentiostatic experiments with LiNi0.5Mn1.5O4 (LMNO) as cathode material at increased cut-off potentials (>4.5 V vs. Li/Li+). A strong dependence of the formation of organophosphates on the applied electrode potential was observed and investigated by quantitative analysis of the formed phosphates. In addition, new possible "fingerprint" compounds for describing the electrolyte status were investigated and compared to existing compounds.

  20. An approach to enhancing coverage of the urinary metabonome using liquid chromatography-ion mobility-mass spectrometry.

    PubMed

    Harry, Emma L; Weston, Daniel J; Bristow, Anthony W T; Wilson, Ian D; Creaser, Colin S

    2008-08-15

    The potential of drift tube ion mobility (IM) spectrometry in combination with high performance liquid chromatography (LC) and mass spectrometry (MS) for the metabonomic analysis of rat urine is reported. The combined LC-IM-MS approach using quadrupole/time-of-flight mass spectrometry with electrospray ionisation, uses gas-phase analyte characterisation based on both mass-to-charge (m/z) ratio and relative gas-phase mobility (drift time) following LC separation. The technique allowed the acquisition of nested data sets, with mass spectra acquired at regular intervals (65 micros) during each IMS separation (approximately 13 ms) and several IMS spectra acquired during the elution of a single LC peak, without increasing the overall analysis time compared to LC-MS. Preliminary results indicate that spectral quality is improved when using LC-IM-MS, compared to direct injection IM-MS, for which significant ion suppression effects were observed in the electrospray ion source. The use of reversed-phase LC employing fast gradient elution reduced sample preparation to a minimum, whilst maintaining the potential for high throughput analysis. Data mining allowed information on specific analytes to be extracted from the complex metabonomic data set. LC-IM-MS based approaches may have a useful role in metabonomic analyses by introducing an additional discriminatory dimension of ion mobility (drift time). PMID:18502703

  1. Determination of major sodium iodide symporter (NIS) inhibitors in drinking waters using ion chromatography with conductivity detector.

    PubMed

    Cengiz, Mehmet Fatih; Bilgin, Ayse Kevser

    2016-02-20

    Goiter is an important health problem all over the world and iodine deficiency is its most common cause. Perchlorate, thiocyanate and nitrate (called as major NIS inhibitors) are known to competitively inhibit iodide uptake by the thyroid gland and thus, human exposure to major NIS inhibitors is a public health concern. In this study, an ion chromatographic method for the determination of most common NIS inhibitor ions in drinking waters was developed and validated. This is the first study where an analytical method is used for the determination of major NIS inhibitors in drinking water by an ion chromatography system in a single run. Chromatographic separations were achieved with an anion-exchange column and separated ions were identified by a conductivity detector. The method was found to be selective, linear, precise accurate and true for all of interested ions. The limits of the detections (LOD) were estimated at 0.003, 0.004 and 0.025mgL(-1) for perchlorate, thiocyanate and nitrate, respectively. Possible interference ions in drinking waters were examined for the best separation of NIS inhibitors. The excellent method validation data and proficiency test result (Z-score for nitrate: -0.1) of the FAPAS(®) suggested that the developed method could be applied for determination of NIS inhibitor residues in drinking waters. To evaluate the usefulness of the method, 75 drinking water samples from Antalya/Turkey were analyzed for NIS inhibitors. Perchlorate concentrations in the samples ranged from not detected (less than LOD) to 0.07±0.02mgL(-1) and the range of nitrate concentrations were found to be 3.60±0.01mgL(-1) and 47.42±0.40mgL(-1). No thiocyanate residues were detected in tested drinking water samples. PMID:26744989

  2. Analysis of inorganic species by capillary electrophoresis-mass spectrometry and ion exchange chromatography-mass spectrometry using an ion spray source.

    PubMed

    Corr, J J; Anacleto, J F

    1996-07-01

    Mixtures of inorganic ions separated by capillary electrophoresis (CE) and ion exchange chromatography (IC) are detected by mass spectrometry (MS) using an ion spray atmospheric pressure ionization source. The selectable degree of ion-adduct declustering and molecular fragmentation in the MS interface region allows the system to be operated as an elemental analyzer or as a molecular detector suitable for oxidation state determinations. Both inorganic anions and cations (including alkalis, alkaline earths, transition metals, and lanthanides) are analyzed by CE-MS. A variety of CE separation buffers are evaluated for the cation analyses (e.g., creatinine, ammonium acetate, and tris[hydroxymethyl]aminomethane). Only one of the buffers (i.e., creatinine) can be used for CE-indirect UV detection. A CE capillary permanently coated with strong anion exchange sites and a pyromellitic acid buffer (suitable for indirect UV detection) is used for the inorganic anion separations. The coated column eliminates the need for buffer modifiers to reverse the flow in the capillary, which then reduces background noise and mass spectral complexity. The separation and detection of 13 inorganic anions are also accomplished by IC using an anion exchange column with a carbonate-bicarbonate mobile phase, on-line suppressed conductivity detection, and mass spectrometric detection. PMID:21619300

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

    EPA Science Inventory

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

  4. Multidimensional Separation of Natural Products Using Liquid Chromatography Coupled to Hadamard Transform Ion Mobility Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Liu, Wenjie; Zhang, Xing; Knochenmuss, Richard; Siems, William F.; Hill, Herbert H.

    2016-05-01

    A high performance liquid chromatograph (HPLC)was interfaced to an atmospheric drift tube ion mobility time of flight mass spectrometry. The power of multidimensional separation was demonstrated using chili pepper extracts. The ambient pressure drift tube ion mobility provided high resolving powers up to 166 for the HPLC eluent. With implementation of Hadamard transform (HT), the duty cycle for the ion mobility drift tube was increased from less than 1% to 50%, and the ion transmission efficiency was improved by over 200 times compared with pulsed mode, improving signal to noise ratio 10 times. HT ion mobility and TOF mass spectrometry provide an additional dimension of separation for complex samples without increasing the analysis time compared with conventional HPLC.

  5. Multidimensional Separation of Natural Products Using Liquid Chromatography Coupled to Hadamard Transform Ion Mobility Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Liu, Wenjie; Zhang, Xing; Knochenmuss, Richard; Siems, William F.; Hill, Herbert H.

    2016-02-01

    A high performance liquid chromatograph (HPLC)was interfaced to an atmospheric drift tube ion mobility time of flight mass spectrometry. The power of multidimensional separation was demonstrated using chili pepper extracts. The ambient pressure drift tube ion mobility provided high resolving powers up to 166 for the HPLC eluent. With implementation of Hadamard transform (HT), the duty cycle for the ion mobility drift tube was increased from less than 1% to 50%, and the ion transmission efficiency was improved by over 200 times compared with pulsed mode, improving signal to noise ratio 10 times. HT ion mobility and TOF mass spectrometry provide an additional dimension of separation for complex samples without increasing the analysis time compared with conventional HPLC.

  6. Multidimensional Separation of Natural Products Using Liquid Chromatography Coupled to Hadamard Transform Ion Mobility Mass Spectrometry.

    PubMed

    Liu, Wenjie; Zhang, Xing; Knochenmuss, Richard; Siems, William F; Hill, Herbert H

    2016-05-01

    A high performance liquid chromatograph (HPLC)was interfaced to an atmospheric drift tube ion mobility time of flight mass spectrometry. The power of multidimensional separation was demonstrated using chili pepper extracts. The ambient pressure drift tube ion mobility provided high resolving powers up to 166 for the HPLC eluent. With implementation of Hadamard transform (HT), the duty cycle for the ion mobility drift tube was increased from less than 1% to 50%, and the ion transmission efficiency was improved by over 200 times compared with pulsed mode, improving signal to noise ratio 10 times. HT ion mobility and TOF mass spectrometry provide an additional dimension of separation for complex samples without increasing the analysis time compared with conventional HPLC. Graphical Abstract ᅟ. PMID:26914233

  7. Size-exclusion chromatography as a stand-alone methodology identifies novel markers in mass spectrometry analyses of plasma-derived vesicles from healthy individuals

    PubMed Central

    de Menezes-Neto, Armando; Sáez, María José Fidalgo; Lozano-Ramos, Inés; Segui-Barber, Joan; Martin-Jaular, Lorena; Ullate, Josep M. Estanyol; Fernandez-Becerra, Carmen; Borrás, Francesc E.; del Portillo, Hernando A.

    2015-01-01

    Plasma-derived vesicles hold a promising potential for use in biomedical applications. Two major challenges, however, hinder their implementation into translational tools: (a) the incomplete characterization of the protein composition of plasma-derived vesicles, in the size range of exosomes, as mass spectrometric analysis of plasma sub-components is recognizably troublesome and (b) the limited reach of vesicle-based studies in settings where the infrastructural demand of ultracentrifugation, the most widely used isolation/purification methodology, is not available. In this study, we have addressed both challenges by carrying-out mass spectrometry (MS) analyses of plasma-derived vesicles, in the size range of exosomes, from healthy donors obtained by 2 alternative methodologies: size-exclusion chromatography (SEC) on sepharose columns and Exo-Spin™. No exosome markers, as opposed to the most abundant plasma proteins, were detected by Exo-Spin™. In contrast, exosomal markers were present in the early fractions of SEC where the most abundant plasma proteins have been largely excluded. Noticeably, after a cross-comparative analysis of all published studies using MS to characterize plasma-derived exosomes from healthy individuals, we also observed a paucity of “classical exosome markers.” Independent of the isolation method, however, we consistently identified 2 proteins, CD5 antigen-like (CD5L) and galectin-3-binding protein (LGALS3BP), whose presence was validated by a bead-exosome FACS assay. Altogether, our results support the use of SEC as a stand-alone methodology to obtain preparations of extracellular vesicles, in the size range of exosomes, from plasma and suggest the use of CD5L and LGALS3BP as more suitable markers of plasma-derived vesicles in MS. PMID:26154623

  8. 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

    Smrke, Samo; Opitz, Sebastian E W; Vovk, Irena; Yeretzian, Chahan

    2013-07-01

    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

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

    PubMed

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

    2013-02-01

    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'β-deacetoxyaustrospicatine. Initial examination of heartwood extracts for 2'β-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'β-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

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

    PubMed

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

    2006-09-18

    A liquid chromatography-ion trap mass spectrometry coupled with electrospray ionization (HPLC-ESI-ion trap mass spectrometry) method for simultaneous determination of cetirizine and pseudoephedrine in human plasma is presented. Chromatographic separation was performed on a Hypurity C18 column (Thermo Hypersil-Keystone 2.1 mm x 150 mm, 5 microm, USA), The mobile phase was composed of 65% methanol and 35% water (contained 0.1% formic acid, 10 mM ammonium formate), which was run with a flow-rate of 0.2 ml/min at 40 degrees C. Quantitation was achieved by monitoring the product ions at m/z 166-->m/z 148 (pseudoephedrine), m/z 389.9-->m/z 201.1 (cetirizine), m/z 264-->m/z 246 (tramadol, IS). The calibration curve of pseudoephedrine and cetirizine was established with standard solutions. The limit of detection for pseudoephedrine and cetirizine each was 5 ng/ml. This simplified analytical method is sensitive, specific and accurate enough for simultaneous determination of pseudoephedrine and cetirizine in human plasma and is successfully applied to the pharmacokinetic study of pseudoephedrine and cetirizine. PMID:16713697

  11. Determination of vinyl chloride in soil-gas samples by gas chromatography coupled with ion mobility spectrometry

    SciTech Connect

    Jones, T.L.; Hill, H.; Simpson, G.; Klasmeier, M.; Lopez-Avila, V.; Radolovich, G.

    1995-12-31

    The advantages of ion mobility spectrometry (IMS), such as ambient pressure operation, simplicity of design, high sensitivity, speed of response, spectral output, and ability to respond to a large number of compounds, make IMS technology attractive for a variety of field monitoring applications. A quantitative, multicompound field detector based on IMS technology has not been successful, however, because of technology limitations. For multicomponent samples, multiple ion-molecule reactions result in confusing spectral information. Varying humidity can result in ion-water clusters that cause errors in both the identification and quantification of the target analyte. These limitations could be overcome through the addition of gas chromatography (GC) prior to high-temperature IMS. When coupling GC to IMS, the following need to be considered: (a) currently available IMS cells have a relatively large internal volume (> 20 mL), reducing the chromatographic resolution; (b) smaller IMS cells are not capable of operating above 100 C; (c) the radioactive ionization cell limits the dynamic range of the device to 2 to 3 orders of magnitude; and (d) most standard miniature cells have a membrane inlet that does not allow direct interface with a GC column. The authors have overcome some of these difficulties by interfacing GC with Fourier Transform IMS (FTIMS). They will present data on determining vinyl chloride in soil-gas samples by GC-FTIMS.

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

    PubMed

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

    2014-11-01

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

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

    PubMed

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

    2013-09-10

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

  14. Ion chromatography as highly suitable method for rapid and accurate determination of antibiotic fosfomycin in pharmaceutical wastewater.

    PubMed

    Zeng, Ping; Xie, Xiaolin; Song, Yonghui; Liu, Ruixia; Zhu, Chaowei; Galarneau, Anne; Pic, Jean-Stéphane

    2014-01-01

    A rapid and accurate ion chromatography (IC) method (limit of detection as low as 0.06 mg L(-1)) for fosfomycin concentration determination in pharmaceutical industrial wastewater was developed. This method was compared with the performance of high performance liquid chromatography determination (with a high detection limit of 96.0 mg L(-1)) and ultraviolet spectrometry after reacting with alizarin (difficult to perform in colored solutions). The accuracy of the IC method was established in the linear range of 1.0-15.0 mg L(-1) and a linear correlation was found with a correlation coefficient of 0.9998. The recoveries of fosfomycin from industrial pharmaceutical wastewater at spiking concentrations of 2.0, 5.0 and 8.0 mg L(-1) ranged from 81.91 to 94.74%, with a relative standard deviation (RSD) from 1 to 4%. The recoveries of effluent from a sequencing batch reactor treated fosfomycin with activated sludge at spiking concentrations of 5.0, 8.0, 10.0 mg L(-1) ranging from 98.25 to 99.91%, with a RSD from 1 to 2%. The developed IC procedure provided a rapid, reliable and sensitive method for the determination of fosfomycin concentration in industrial pharmaceutical wastewater and samples containing complex components. PMID:24845315

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  17. Behaviour of different eluents and stabilizing agents in the determination of sulphite in water by ion-chromatography.

    PubMed

    Campanella, L; Majone, M; Pocci, R

    1990-02-01

    Ion-chromatography has been used for the determination of sulphite in water. The eluents were solutions of Na(2)CO(3) (1.1mM)-NaHCO(3) (1.4mM) or NaHCO(3) (1.0mM)-formaldehyde (0.2% w/w), and formaldehyde, glycerol or fructose was used as stabilizing agent. With the first eluent, fructose or glycerol can be used to stabilize samples against sulphite oxidation, but formaldehyde affects the peak height. On the other hand, formaldehyde can stabilize sulphite in the presence of Fe(III), whereas glycerol and fructose can not. If Fe(III) is present, the second eluent is used and sulphite is eluted directly as hydroxymethanesulphonate; formaldehyde will not then affect the peak height. This eluent allows a good peak separation and is suitable for the sulphite concentration range 0.1-12.0 mg/l. PMID:18964930

  18. Purification of genus-specific chlamydial antigen and its separation into several components by ion-exchange chromatography.

    PubMed Central

    Schmeer, N; Krauss, H

    1982-01-01

    Sodium deoxycholate-extracted genus-specific chlamydial antigen was purified from contaminating substances by ion-exchange chromatography with DEAE-sephacel, resulting in a decrease in the complement-fixing activity of the antigen, whereas the enzyme-linked immunosorbent assay activity increased. By successive elution with 0.5, 1.0, and 1.5 M acetate buffer at least three clearly separated components were consistently recovered in 14 trials. The identity of these components as genus-specific chlamydial antigen was demonstrated in enzyme-linked immunosorbent assay tests with specific antisera. The antigenic activity of these components was not diminished by prior treatment of the chlamydial particles with pronase. Antiserum prepared by immunization of rabbits with the antigenic component I of an egg-propagated antigen reacted predominantly with the antigenic components I and II of a cell culture-propagated antigen. PMID:7096557

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

    PubMed

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

    2004-09-22

    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

  20. Simultaneous determination of triprolidine and pseudoephedrine in human plasma by liquid chromatography-ion trap mass spectrometry.

    PubMed

    Shakya, Ashok K; Arafat, Tawfiq A; Abuawwad, Ahmad N; Melhim, Munther; Al-Ghani, Jafar; Yacoub, Mahmoud J

    2009-12-15

    A highly efficient, selective and specific method for simultaneous quantitation of triprolidine and pseudoephedrine in human plasma by liquid chromatography-ion trap-tandem mass spectrometry coupled with electro spray ionization (LC-ESI-ion trap-tandem MS) has been validated and successfully applied to a clinical pharmacokinetic study. Both targeted compounds together with the internal standard (gabapentin) were extracted from the plasma by direct protein precipitation. Chromatographic separation was achieved on a C(18) ACE((R)) column (50.0mmx2.1mm, 5mum, Advance Chromatography Technologies, Aberdeen, UK), using an isocratic mobile phase, consisting of water, methanol and formic acid (55:45:0.5, v/v/v), at a flow-rate of 0.3mL/min. The transition monitored (positive mode) was m/z 279.1-->m/z 208.1 for triprolidine, m/z 165.9-->m/z 148.0 for pseudoephedrine and m/z 172.0-->m/z 154.0 for gabapentin (IS). This method had a chromatographic run time of 5.0min and a linear calibration curves ranged from 0.2 to 20.0ng/mL for triprolidine and 5.0-500.0ng/mL for pseudoephedrine. The within- and between-batch accuracy and precision (expressed as coefficient of variation, %C.V.) evaluated at four quality control levels were within 94.3-106.3% and 1.0-9.6% respectively. The mean recoveries of triprolidine, pseudoephedrine and gabapentin were 93.6, 76.3 and 82.0% respectively. Stability of triprolidine and pseudoephedrine was assessed under different storage conditions. The validated method was successfully employed for the bioequivalence study of triprolidine and pseudoephedrine formulation in twenty six volunteers under fasting conditions. PMID:19926351

  1. Alternative purification method for recombinant measles viral nucleoprotein expressed in insect cells by ion-exchange chromatography.

    PubMed

    Lee, Han Saem; Kim, You-Jin; Yang, Jeongsun; Yoon, Hee Sook; Kim, Seung Tae; Kim, Kisoon

    2014-03-01

    Recombinant measles virus nucleoproteins (rMeV N) and fusion (F) proteins were characterized as major antigenic proteins expressed in insect cells mediated by recombinant baculoviruses (rBVs). Band intensities were analyzed by Western blotting to recognize IgG and IgM antibodies against the rMeV N and F proteins in human sera and cerebrospinal fluids (CSFs) from patients with measles infections. Positive results from the blots using the rMeV N were consistent with the results of enzyme-linked immunosorbent assays (ELISAs) in which whole viral proteins were used as antigens. Human sera and CSFs reacted more strongly with the rMeV N than with the rMeV F proteins prepared in an identical expression system. For efficient and reliable purification, ion-exchange chromatography using Source Q anion resin was applied, and high-purity rMeV N protein was harvested. To characterize the similarity with the native viral protein to purified N protein, structural mimicry of purified recombinant proteins with intact rMeV N was shown through transmission electron microscopy, and the truncation and the phosphorylation status of the expressed protein were analyzed. These results suggest that the rMeV N purified by ion-exchange chromatography has features similar to those of naïve N including a self-assembled structure, phosphorylation and antigenic function. Thus, these expression and purification methods can be applied to the large-scale production of the rMeV N, which is essential for the development of new diagnostic tools and vaccines for acute and chronic MeV infections. PMID:24355696

  2. Influence of carboxylic ion-pairing reagents on retention of peptides in thin-layer chromatography systems with C18 silica-based adsorbents.

    PubMed

    Gwarda, Radosław Ł; Aletańska-Kozak, Monika; Klimek-Turek, Anna; Ziajko-Jankowska, Agnieszka; Matosiuk, Dariusz; Dzido, Tadeusz H

    2016-04-01

    One of the main problems related to chromatography of peptides concerns adverse interactions of their strong basic groups with free silanol groups of the silica based stationary phase. Influence of type and concentration of ion-pairing regents on peptide retention in reversed-phase high-performance liquid chromatography (RP-HPLC) systems has been discussed before. Here we present influence of these mobile phase additives on retention of some peptide standards in high-performance thin-layer chromatography (HPTLC) systems with C18 silica-based adsorbents. We prove, that due to different characteristic of adsorbents used in both techniques (RP HPLC and HPTLC), influence of ion-pairing reagents on retention of basic and/or amphoteric compounds also may be quite different. C18 silica-based HPTLC adsorbents provide more complex mechanism of retention and should be rather considered as mixed-mode adsorbents. PMID:26944833

  3. Appropriate choice of collision-induced dissociation energy for qualitative analysis of notoginsenosides based on liquid chromatography hybrid ion trap time-of-flight mass spectrometry.

    PubMed

    Wang, Guang-Ji; Fu, Han-Xu; Xiao, Jing-Cheng; Ye, Wei; Rao, Tai; Shao, Yu-Hao; Kang, Dian; Xie, Lin; Liang, Yan

    2016-04-01

    Liquid chromatography hybrid ion trap/time-of-flight mass spectrometry possessesd both the MS(n) ability of ion trap and the excellent resolution of a time-of-flight, and has been widely used to identify drug metabolites and determine trace multi-components for in natural products. Collision energy, one of the most important factors in acquiring MS(n) information, could be set freely in the range of 10%-400%. Herein, notoginsenosides were chosen as model compounds to build a novel methodology for the collision energy optimization. Firstly, the fragmental patterns of the representatives for the authentic standards of protopanaxadiol-type and protopanaxatriol-type notoginsenosides authentic standards were obtained based on accurate MS(2) and MS(3) measurements via liquid chromatography hybrid ion trap/time-of-flight mass spectrometry. Then the extracted ion chromatograms of characteristic product ions of notoginsenosides in Panax Notoginseng Extract, which were produced under a series of collision energies and, were compared to screen out the optimum collision energies values for MS(2) and MS(3). The results demonstrated that the qualitative capability of liquid chromatography hybrid ion trap/time-of-flight mass spectrometry was greatly influenced by collision energies, and 50% of MS(2) collision energy was found to produce the highest collision-induced dissociation efficiency for notoginsenosides. BesidesAddtionally, the highest collision-induced dissociation efficiency appeared when the collision energy was set at 75% in the MS(3) stage. PMID:27114315

  4. 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...

  5. Speciation of arsenic(III)/arsenic(V) and selenium(IV)/ selenium(VI) using coupled ion chromatography - hydride generation atomic absorption spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Simple analytical methods have been developed to speciate inorganic arsenic and selenium in the ppb range using coupled ion chromatography-hydride generation atomic absorption spectrometry. Because of the differences in toxicity and adsorption behavior, determinations of the redox states arsenite A...

  6. Application of linear pH gradients for the modeling of ion exchange chromatography: Separation of monoclonal antibody monomer from aggregates.

    PubMed

    Kluters, Simon; Wittkopp, Felix; Jöhnck, Matthias; Frech, Christian

    2016-02-01

    The mobile phase pH is a key parameter of every ion exchange chromatography process. However, mechanistic insights into the pH influence on the ion exchange chromatography equilibrium are rare. This work describes a mechanistic model capturing salt and pH influence in ion exchange chromatography. The pH dependence of the characteristic protein charge and the equilibrium constant is introduced to the steric mass action model based on a protein net charge model considering the number of amino acids interacting with the stationary phase. This allows the description of the adsorption equilibrium of the chromatographed proteins as a function of pH. The model parameters were determined for a monoclonal antibody monomer, dimer, and a higher aggregated species based on a manageable set of pH gradient experiments. Without further modification of the model parameters the transfer to salt gradient elution at fixed pH is demonstrated. A lumped rate model was used to predict the separation of the monoclonal antibody monomer/aggregate mixture in pH gradient elution and for a pH step elution procedure-also at increased protein loadings up to 48 g/L packed resin. The presented model combines both salt and pH influence and may be useful for the development and deeper understanding of an ion exchange chromatography separation. PMID:26549715

  7. 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

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

    2004-01-01

    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.

  8. DETERMINATION OF A BOUND MUSK XYLENE METABOLITE IN CARP HEMOGLOBIN AS A BIOMARKER OF EXPOSURE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY USING SELECTED ION MONITORING

    EPA Science Inventory

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occur...

  9. 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...

  10. 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...

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

    PubMed

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

    2008-12-01

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

  12. Metabolite Profile of Salidroside in Rats by Ultraperformance Liquid Chromatography Coupled with Quadrupole Time-of-Flight Mass Spectrometry and High-Performance Liquid Chromatography Coupled with Quadrupole-Linear Ion Trap Mass Spectrometry.

    PubMed

    Hu, Zhiwei; Wang, Ziming; Liu, Yong; Wu, Yan; Han, Xuejiao; Zheng, Jian; Yan, Xiufeng; Wang, Yang

    2015-10-21

    In the present work, the salidroside metabolite profile in rat urine was investigated, and subsequently the metabolic pathways of salidroside were proposed. After administrations of salidroside at an oral dose of 100 or 500 mg/kg, rat urine samples were collected and pretreated with methanol to precipitate the proteins. The pretreated samples were analyzed by an Acquity ultraperformance liquid chromatography (UPLC) coupled with an HSS T3 column and detected by quadrupole time-of-flight mass spectrometry (Q-TOF-MS) or high-performance liquid chromatography coupled with hybrid triple-quadrupole linear ion trap mass spectrometry (HPLC/Q-trap-MS). A total of eight metabolites were detected and identified on the basis of the characteristics of their protonated ions in the urine samples. The results elucidated that salidroside was metabolized via glucuronidation, sulfation, deglycosylation, hydroxylation, methylation, and dehydroxylation pathways in vivo. PMID:26461036

  13. Phenolic profile characterization of Chemlali olive stones by liquid chromatography-ion trap mass spectrometry.

    PubMed

    Ben Mansour, Amir; Porter, Elaine A; Kite, Geoffrey C; Simmonds, Monique S J; Abdelhedi, Ridha; Bouaziz, Mohamed

    2015-02-25

    Aqueous methanol extracts of Chemlali olive stones were analyzed by reverse phase high-performance liquid chromatography (HPLC) with diode array detection and mass spectrometry [LC-MS/MS]. Oleoside, oleoside 11-methyl ester, nuezhenide, oleoside 11-methyloleoside, nuezhenide 11-methyloleoside, oleuropein, and glycosides of tryosol and hydroxytyrosol glycosides were identified in stones of Chemali olives. The antioxidant activity observed for the extract of the olive stones (IC50 = 13.84 μg/mL, TEAC = 0.436 mM) may be due to the high content of phenolic compounds, of which the main compounds are nuezhenide (325.78 mg/100g), methoxy derivative of nuezhenide (132.46 mg/100g), and nuezhenide-11-methyloleoside (82.91 mg/100g). These results suggest the use of olive stones as sources of natural antioxidants. PMID:25650173

  14. Improvements in macroreticular particles for ion-exchange and gel-permeation chromatography

    SciTech Connect

    Watson, J.S.

    1990-01-01

    The effectiveness of chromatographic processes is often limited by the resistance to mass transfer into the exchanger particles. The likelihood of the exchange process being limited by particle diffusion resistance is especially high when one or both of the exchanging ions has a high molecular weight, and thus large molecular size and low mobility within the particles. Separation of ionic species from bioreactors is likely to involve such high molecular weight species and slow diffusion rates. Macroreticular particles are more effective in these applications because the larger specie can diffuse more freely into the inner regions of the particles through large pores. The effects of small viscous flow rates through the larger pores of the macroreticular particle structure are examined in this paper to show how such flow can increase exchange rates. The importance of such flow is evaluated in terms of an effective diffusivity within the particle. The performance of an ion-exchange material can be affected strongly by the dimensions of its internal structure. The approach used to describe and evaluate the performance of ion-exchange materials with high-molecular-weight ions can be applied to macroreticular particles for separation of biological species and polymers by gel permeation. 7 refs., 2 figs.

  15. [Simultaneous determination of chlormequat chloride and mepiquat chloride in plants by mobile phase ion chromatography].

    PubMed

    Zhou, Xu; Xu, Jingang; Chen, Zhidong; Zhu, Yan

    2011-03-01

    Ion-pair reagent was used as mobile phase for the simultaneous separation of chlormequat chloride and mepiquat chloride in plants. The rapid separation was performed on a Dionex IonPac NG1 guard column and a Dionex IonPac NS1 analytical column using 1.0 mL/min of the eluent mixture of 1.00 mmol/L nonafluoropentanoic acid (as ion-pair reagent) and 7% acetonitrile, and the detection was achieved by a suppressed conductivity detector. The method provided good resolution of the analyte peaks without any interference. The detection limits of chlormequat chloride and mepiquat chloride were 0.154 6 mg/L and 0.171 4 mg/L, respectively. The linear calibration curves were obtained in the range of 1 - 100 mg/L. The mean recoveries in the ranges of 96.06% - 104.6% for chlormequat chloride and 98.53% - 103.7% for mepiquat chloride were obtained in real samples. The method requires only simple sample preparation and the technique is suitable for routine quality control analysis. PMID:21657055

  16. 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...

  17. High-resolution determination of {sup 147}Pm in urine using dynamic ion-exchange chromatography

    SciTech Connect

    Elchuk, S.; Lucy, C.A.; Burns, K.I.

    1992-10-15

    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.

  18. 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...

  19. 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...

  20. CRC handbook of chromatography

    SciTech Connect

    Qureshi, M.

    1986-01-01

    This book provides technology for routine analysis or developing new methods of chromatography or organic materials. In this book Section 1 presents the principles, techniques, quantitative determinations and detection methods used in chromatographic analysis. In the major part of the book, Section 2 summarizes data in voluminous tabular/graphic form on paper, thin layer, liquid and gas chromatography. Section 3 lists important books on electrophoreses, gel permeation chromatography, and ion exchange, in addition to the other forms of chromatography.

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

    PubMed

    Gu, Ming; Wang, Yongdong; Zhao, Xian-Guo; Gu, Zhe-Ming

    2006-01-01

    Acceleration of liquid chromatography/mass spectrometric (LC/MS) analysis for metabolite identification 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 that can suffer severely from matrix effects. This paper describes a new method to automatically extract and filter metabolite-related information from LC/MS data obtained at unit mass resolution in the presence of complex biological matrices. This approach is illustrated by LC/MS analysis of the metabolites of verapamil from a rat microsome incubation spiked with biological matrix (bile). MS data were acquired in profile mode on a unit mass resolution triple-quadrupole instrument, externally calibrated using a unique procedure that corrects for both mass axis and mass spectral peak shape to facilitate metabolite identification with high mass accuracy. Through the double-filtering effects of accurate mass and isotope profile, conventional extracted ion chromatograms corresponding to the parent drug (verapamil at m/z 455), demethylated verapamil (m/z 441), and dealkylated verapamil (m/z 291), that contained substantial false-positive peaks, were simplified into chromatograms that are substantially free from matrix interferences. These filtered chromatograms approach what would have been obtained by using a radioactivity detector to detect radio-labeled metabolites of interest. PMID:16463359

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

    PubMed

    Zakon, Yevgeni; Halicz, Ludwik; Gelman, Faina

    2014-07-01

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

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

    SciTech Connect

    Jantzen, C.M.

    1990-10-01

    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.

  4. [Determination of 16 polychlorinated biphenyls in fish oil by gas chromatography-negative ion chemical ionization-mass spectrometry].

    PubMed

    Wang, Li; Li, Shushu; Zhang, Zhan; Wang, Shoulin; Li, Lei

    2015-08-01

    An analytical method for the simultaneous determination of 16 polychlorinated biphenyls (PCBs) in fish oil was developed. PCBs were extracted from fish oil with n-hexane, purified by sulfuric acid and determined by using gas chromatography-negative ion chemical ionization-mass spectrometry (GC-NCI-MS) in selected ion-monitoring (SIM) mode. A good linear relationship (r > 0.99) was observed with the PCBs concentrations from 0.01 µg/L to 10 µg/L, and the limits of quantification (LOQ, S/N = 10) were between 3 pg/g and 67 pg/g for different kinds of PCBs. The average recoveries ranged from 62.3% to 121.8% with the relative standard deviations ( RSDs, n = 3) smaller than 12%. Compared with the traditional pre-treatment of multiple material solid phase extraction, this new method is simple, rapid and less organic solvent usage. Meanwhile the method has good selectivity and sensitivity, and it is suitable for the determination of multiple trace PCBs in fish oil. PMID:26749866

  5. Determination of four tobacco-specific nitrosamines in mainstream cigarette smoke by gas chromatography/ion trap mass spectrometry.

    PubMed

    Zhou, Jun; Bai, Ruoshi; Zhu, Yongfa

    2007-01-01

    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

  6. Identification of novel isomeric pectic oligosaccharides using hydrophilic interaction chromatography coupled to traveling-wave ion mobility mass spectrometry.

    PubMed

    Leijdekkers, Antonius G M; Huang, Jie-Hong; Bakx, Edwin J; Gruppen, Harry; Schols, Henk A

    2015-03-01

    Separation and characterization of complex mixtures of pectic oligosaccharides still remains challenging and often requires the use of multiple analytical techniques, especially when isomeric structures are present. In this work, it is demonstrated that the coupling of hydrophilic interaction chromatography (HILIC) to traveling-wave ion mobility mass spectrometry (TWIMMS) enabled the simultaneous separation and characterization of complex mixtures of various isomeric pectic oligosaccharides. Labeling of oligosaccharides with 3-aminoquinoline (3-AQ) improved MS-ionization efficiency of the oligosaccharides and reduced the complexity of the product ion mass spectra, without losing resolution of the HILIC separation. In addition, labeling enabled quantification of oligosaccharides on molar basis using in-line fluorescence detection. Isomeric structures were distinguished using TWIMMS. The 3-AQ-HILIC-TWIMMS method was used to characterize a series of isomeric sugar beet rhamnogalacturonan I derived oligosaccharides carrying a glucuronic acid substituent. Thereby, some novel structural features were identified for the first time: glucuronic acid was attached to O-3 or to O-2 of galacturonic acid residues and a single galacturonic acid residue within an oligomer could contain both an acetyl group and a glucuronic acid substituent. PMID:25647688

  7. A new approach for trace analysis of guanidine compounds in surface water with resorcinarene-based ion chromatography columns.

    PubMed

    Panahi, Tayyebeh; Weaver, Douglas J; Lamb, John D; Harrison, Roger G

    2016-01-25

    Trace levels of pharmaceuticals have been detected in surface water and may pose a health risk to humans and other organisms. New chromatographic materials will help identify and quantify these contaminants. We introduce a new ion chromatographic (IC) material designed to separate cationic pharmaceuticals and report its ability to separate a group of guanidine compounds. Guanidine moieties are strongly basic and protonated under acid conditions, and therefore can potentially be separated on the newly designed stationary phase and detected by ion exchange chromatography. The new column packing material is based on glutamic acids bonded to resorcinarene moieties that in turn are bound to divinylbenzene macroporous resin. Detection limits in the range of 5-30 μg L(-1) were achieved using integrated pulsed amperometric detection (IPAD) for guanidine (G), methylguanidine (MG), 1,1-dimethylbiguanide (DMG), agmatine (AGM), guanidinobenzoic acid (GBA) and cimetidine (CIM). Suppressed conductivity (CD) and UV-vis detection resulted in limits of detection similar to IPAD, in the range of 2-66 μg L(-1), but were not able to detect all of the analytes. Three water sources, river, lake, and marsh, were analyzed and despite matrix effects, sensitivity for guanidine compounds was in the 100 μg L(-1) range and apparent recoveries were 80-96%. The peak area precision was 0.01-2.89% for IPAD, CD and UV-vis detection. PMID:26649362

  8. Identification and separation of saxitoxins using hydrophilic interaction liquid chromatography coupled to traveling wave ion mobility-mass spectrometry.

    PubMed

    Poyer, Salom; Loutelier-Bourhis, Corinne; Coadou, Gal; Mondeguer, Florence; Enche, Julien; Bosse, Anne; Hess, Philipp; Afonso, Carlos

    2015-01-01

    The aim of this work was to develop a reliable and efficient analytical method to characterise and differentiate saxitoxin analogues (STX), including sulphated (gonyautoxins, GTX) and non-sulphated analogues. For this purpose, hydrophilic interaction liquid chromatography (HILIC) was used to separate sulphated analogues. We also resorted to ion mobility spectrometry to differentiate the STX analogues because this technique adds a new dimension of separation based on ion gas phase conformation. Positive and negative ionisation modes were used for gonyautoxins while positive ionisation mode was used for non-sulphated analogues. Subsequently, the coupling of these three complementary techniques, HILIC-IM-MS, permitted the separation and identification of STX analogues; isomer differentiation was achieved in HILIC dimension while non-sulphated analogues were separated in the IM-MS dimension. Additional structural characteristics concerning the conformation of STXs could be obtained using IM-MS measurements. Thus, the collision cross sections (CCS) of STXs are reported for the first time in the positive ionisation mode. These experimental CCSs correlated well with the calculated CCS values using the trajectory method. PMID:25601690

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  10. Simultaneous analysis of strychnine and brucine and their major metabolites by liquid chromatography-electrospray ion trap mass spectrometry.

    PubMed

    Chen, Xueguo; Lai, Yongquan; Cai, Zongwei

    2012-04-01

    A liquid chromatography-electrospray ionization-ion trap mass spectrometry (LC-ESI-ITMS) method was developed for the simultaneous analysis of strychnine, brucine and their major metabolites. Strychnine and brucine were individually incubated with rat liver S9 fraction. The incubation samples were pooled together and analyzed with LC-ESI-ITMS in positive ion and full-scan detection mode. The calibration curves of strychnine and brucine in rat liver showed good linearity in ranges of 0.020 to 8.0 µg/mL for strychnine and 0.020 to 8.5 µg/mL for brucine. The limits of detections were both 0.008 µg/mL and the recoveries were 88.3 and 83.2% for strychnine and brucine, respectively. Two metabolites were identified as strychnine N-oxide and brucine N-oxide by comparing the molecular mass, retention time, full-scan mass spectra, tandem MS and MS(3) spectra with those of strychnine and brucine. The developed method provided high sensitivity and selectivity for the determination of poisonous alkaloids and their major metabolites and can be applied in the determination of samples in forensic and clinically toxicological cases. PMID:22417832

  11. Metallomics approach to trace element analysis in ustilago maydis using cellular fractionation, atomic absorption spectrometry, and size exclusion chromatography with ICP-MS detection.

    PubMed

    Muñoz, Alma Hortensia Serafin; Kubachka, Kevin; Wrobel, Kazimierz; Corona, Felix Gutierrez; Yathavakilla, Santha K V; Caruso, Joseph A; Wrobel, Katarzyna

    2005-06-29

    Huitlacoche is the ethnic name of the young fruiting bodies of Ustilago maydis, a common parasite of maize. In Mexico and other Latin American countries, this fungus has been traditionally appreciated as a local delicacy. In this work a metallomics approach was used with the determination of eight elements in huitlacoche by electrothermal atomic absorption spectrometry as one facet of this approach. The results obtained indicated relatively lower concentrations of commonly analyzed metals, as referred to the data reported for other mushroom types. This effect was ascribed to different accessibilities of elements, depending on fungus substrate (lower from plant than from soil). Subcellular fractionation was accomplished by centrifugation of cell homogenates suspended in Tris-HCl buffer. Recoveries of the fractionation procedure were in the range of 71-103%. For six elements (Cr, Cu, Fe, Mn, Ni, and Pb), the mean relative contributions in cytosol, cell walls, and mixed membrane fraction were 50.7, 48.2, and 1.1% respectively. To attain the molecular weight distribution of compounds containing target elements as an additional aspect of the metallomics approach, the fungus extract (1% sodium dodecyl sulfate in Tris-HCl, 30 mmol L(-)(1), pH 7.0) was analyzed by size exclusion chromatography with UV and ICP-MS detection. With spectrophotometric detection (280 nm), the elution of high molecular weight compounds was observed in the form of one peak (MW > 10 kDa), and several lower peaks appeared at higher retention times (MW < 10 kDa). On ICP-MS chromatograms, a coelution of (59)Co, (63)Cu, (57)Fe, (202)Hg, (60)Ni, and (80)Se with the first peak on the UV chromatogram was clearly observed, indicating that a fraction of each element incorporated with high molecular weight compounds (12.7, 19.8, 33.7, 100, 19.4, and 45.8%, respectively, based on the peak area measurements). From a comparison of (80)Se and (33)S chromatograms (for sulfur analysis, the extract was obtained in the absence of SDS), both elements coeluted with the first UV peak, but their lower molecular weight compounds were apparently different. These findings may contribute to a better understanding of the accumulation of elements in mushrooms. PMID:15969488

  12. Development Of Ion Chromatography Methods To Support Testing Of The Glycolic Acid Reductant Flowsheet In The Defense Waste Processing Facility

    SciTech Connect

    Wiedenman, B. J.; White, T. L.; Mahannah, R. N.; Best, D. R.; Stone, M. E.; Click, D. R.; Lambert, D. P.; Coleman, C. J.

    2013-10-01

    Ion Chromatography (IC) is the principal analytical method used to support studies of Sludge Reciept and Adjustment Tank (SRAT) chemistry at DWPF. A series of prior analytical ''Round Robin'' (RR) studies included both supernate and sludge samples from SRAT simulant, previously reported as memos, are tabulated in this report.2,3 From these studies it was determined to standardize IC column size to 4 mm diameter, eliminating the capillary column from use. As a follow on test, the DWPF laboratory, the PSAL laboratory, and the AD laboratory participated in the current analytical RR to determine a suite of anions in SRAT simulant by IC, results also are tabulated in this report. The particular goal was to confirm the laboratories ability to measure and quantitate glycolate ion. The target was + or - 20% inter-lab agreement of the analyte averages for the RR. Each of the three laboratories analyzed a batch of 12 samples. For each laboratory, the percent relative standard deviation (%RSD) of the averages on nitrate, glycolate, and oxalate, was 10% or less. The three laboratories all met the goal of 20% relative agreement for nitrate and glycolate. For oxalate, the PSAL laboratory reported an average value that was 20% higher than the average values reported by the DWPF laboratory and the AD laboratory. Because of this wider window of agreement, it was concluded to continue the practice of an additional acid digestion for total oxalate measurement. It should also be noted that large amounts of glycolate in the SRAT samples will have an impact on detection limits of near eluting peaks, namely Fluoride and Formate. A suite of scoping experiments are presented in the report to identify and isolate other potential interlaboratory disceprancies. Specific ion chromatography inter-laboratory method conditions and differences are tabulated. Most differences were minor but there are some temperature control equipment differences that are significant leading to a recommendation of a heated jacket for analytical columns that are remoted for use in radiohoods. A suggested method improvement would be to implement column temperture control at a temperature slightly above ambient to avoid peak shifting due to temperature fluctuations. Temperature control in this manner would improve short and longer term peak retention time stability. An unknown peak was observed during the analysis of glycolic acid and SRAT simulant. The unknown peak was determined to best match diglycolic acid. The development of a method for acetate is summaraized, and no significant amount of acetate was observed in the SRAT products tested. In addition, an alternative Gas Chromatograph (GC) method for glycolate is summarized.

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

    PubMed

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

    2014-01-15

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

  14. Ion size effects upon ionic exclusion from dielectric interfaces and slit nanopores

    NASA Astrophysics Data System (ADS)

    Buyukdagli, Sahin; Achim, C. V.; Ala-Nissila, T.

    2011-05-01

    A previously developed field-theoretic model (Coalson et al 1995 J. Chem. Phys. 102 4584) that treats core collisions and Coulomb interactions on the same footing is investigated in order to understand ion size effects on the partition of neutral and charged particles at planar interfaces and the ionic selectivity of slit nanopores. We introduce a variational scheme that can go beyond the mean-field (MF) regime and couple in a consistent way pore-modified core interactions, steric effects, electrostatic solvation and image-charge forces, and surface charge induced electrostatic potential. Density profiles of neutral particles in contact with a neutral hard wall, obtained from Monte Carlo (MC) simulations are compared with the solutions of mean-field and variational equations. A recently proposed random-phase approximation (RPA) method is tested as well. We show that in the dilute limit, the MF and the variational theories agree well with simulation results, in contrast to the RPA method. The partition of charged Yukawa particles at a neutral dielectric interface (e.g. an air-water or protein-water interface) is investigated. It is shown that as a result of the competition between core collisions that push the ions toward the surface, and repulsive solvation and image forces that exclude them from the interface, a concentration peak of finite size ions sets in close to the dielectric interface. This effect is amplified with increasing ion size and bulk concentration. An integral expression for the surface tension that accounts for excluded volume effects is computed and the decrease of the surface tension with increasing ion size is illustrated. We also characterize the role played by the ion size in the ionic selectivity of neutral slit nanopores. We show that the complex interplay between electrostatic forces, excluded volume effects induced by core collisions and steric effects leads to an unexpected reversal in the ionic selectivity of the pore with varying pore size: while large pores exhibit a higher conductivity for large ions, narrow pores exclude large ions more efficiently than small ones.

  15. Exclusive processes in electron-ion collisions in the dipole formalism

    SciTech Connect

    Cazaroto, E. R.; Navarra, F. S.; Carvalho, F.; Goncalves, V. P.

    2013-03-25

    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.

  16. Determination of ammonium in a buddingtonite sample by ion-chromatography

    USGS Publications Warehouse

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

    1986-01-01

    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.

  17. Potential effects of surface water components on actinide determinations conducted by ion chromatography.

    PubMed

    Reboul, S H; Fjeld, R A

    1995-04-01

    An elution program for separating actinides (thorium, uranium, neptunium, plutonium, americium, and curium) on low hydrophobicity ion exchange columns was evaluated for solutions spiked with actinides and common surface water components. Potential interferences from dissolved ions (Na+, K+, Ca2+, Cl-, and SO(4)2-), humic acid, and radium were investigated. Sulfate levels greater than 0.25 mumol interfered with separation of americium, curium, and plutonium. Humic acid levels above 100 micrograms produced distinct widening of actinide peaks and reduced actinide recoveries. These interferences limit the range of useful sample volumes and create a need for sample pretreatment procedures. No interferences were produced by 0.025 to 2.5 mumol Ca2+, 0.045 to 4.5 mumol Na+, 0.015 to 1.5 mumol K+, and 0.025 to 4.5 mumol Cl-. In the absence of interferences, the program effectively separated radium from the actinides. PMID:7883573

  18. Bromate peak distortion in ion chromatography in samples containing high chloride concentrations.

    PubMed

    Pappoe, Michael K; Naeeni, Mohammad Hosein; Lucy, Charles A

    2016-04-29

    In this study, the effect of column overload of the matrix ion, chloride, on the elution peak profiles of trace bromate is investigated. The resultant peak profiles of chloride and bromate are explained on the basis of competitive Langmuir isotherms. The Thermo IonPac AS9-HC, AS19 and AS23 columns are recommended by the manufacturer for bromate (a carcinogen) analysis. Under trace conditions, these columns provide baseline resolution of bromate from matrix ions such as chloride (Rs=2.9, 3.3 and 3.2, respectively for the three columns). Injection of 10-300mM chloride with both hydroxide and carbonate eluents resulted in overload on these columns. On the basis of competitive Langmuir isotherms, a deficiency in the local concentration of the more retained eluent in addition to analyte overload leads to fronting of the overloaded analyte peak. The peak asymmetries (B/A10%) for chloride changed from 1.0 (Gaussian) under trace conditions to 0.7 (fronting) at 300mM Cl(-) for IonPac AS9-HC, 0.9-0.6 for AS19 and 0.8-0.5, for AS23, respectively. The 10mM bromate peak is initially near Gaussian (B/A10%=0.9) but becomes increasingly distorted and pulled back into the chloride peak as the concentration of chloride increased. Increasing the eluent strength reduced the pull-back effect on bromate and fronting in chloride in all cases. PMID:27046004

  19. DETERMINATION OF CARBOXYLIC ACIDS BY ION-EXCLUSION CHROMATOGRAPHY WITH NON-SUPPRESSED CONDUCTIVITY AND OPTICAL DETECTORS

    EPA Science Inventory

    Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. he background conductance of I-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. sing 0.2 MM I-octanesulfonic acid as a mobile p...

  20. DETERMINATION OF CARBOXYLIC ACIDS BY ION-EXCLUSION CHROMATOGRAPHY WITH NON-SUPPRESSED CONDUCTIVITY AND OPTICAL DETECTORS

    EPA Science Inventory

    Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. The background conductance of 1-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. Using 0.2 mM 1-octanesulfonic acid as a mobile...

  1. Gas chromatography/ion mobility spectrometry as a hyphenated technique for improved explosives detection and analysis

    NASA Technical Reports Server (NTRS)

    Mercado, AL; Marsden, Paul

    1995-01-01

    Ion Mobility Spectrometry (IMS) is currently being successfully applied to the problem of on-line trace detection of plastic and other explosives in airports and other facilities. The methods of sample retrieval primarily consist of batch sampling for particulate residue on a filter card for introduction into the IMS. The sample is desorbed into the IMS using air as the carrier and negative ions of the explosives are detected, some as an adduct with a reagent ion such as Cl(-). Based on studies and tests conducted by different airport authorities, this method seems to work well for low vapor pressure explosives such as RDX and PETN, as well as TNT that are highly adsorptive and can be found in nanogram quantities on contaminated surfaces. Recently, the changing terrorist threat and the adoption of new marking agents for plastic explosives has meant that the sample introduction and analysis capabilities of the IMS must be enhanced in order to keep up with other detector developments. The IMS has sufficient analytical resolution for a few threat compounds but the IMS Plasmogram becomes increasingly more difficult to interpret when the sample mixture gets more complex.

  2. Improved determination of tributyl phosphate degradation products (mono- and dibutyl phosphates) by ion chromatography.

    PubMed

    Dodi, A; Verda, G

    2001-06-22

    Tributyl phosphate (TBP) is a very important compound in the nuclear industry, particularly in the area of nuclear fuel reprocessing. This compound is used in the PUREX (plutonium and uranium refining extraction) process which consists of the extraction of uranium and plutonium from an aqueous nitric acid phase, for the purpose of recycling. But TBP may be degraded to dibutyl phosphate (DBP) and monobutyl phosphate (MBP) by dealkylation of one or two butoxy groups, respectively. We have compared and evaluated the capacity of two resins manufactured by Dionex (AS11 and AS5A) in the separation and measurement of these two degradation products. AS11 generates two interferences: nitrite/DBP and carbonate/MBP. The first one is the most serious. So, we have developed a method for oxidising nitrite ions to nitrate ions which have no trouble over the measurement. The second resin tested, AS5A, allows a very efficient separation between DBP and NO2- ions and a good separation between MBP and CO3(2-) in comparison with the AS11. The detection limits for the AS5A column are 0.13 microM for MBP and 0.71 microM for DBP (injection loop=50 microl). PMID:11453010

  3. Determination of the nitrogen content of nitrocellulose from smokeless gunpowders and collodions by alkaline hydrolysis and ion chromatography.

    PubMed

    López-López, María; Alegre, Jose María Ramiro; García-Ruiz, Carmen; Torre, Mercedes

    2011-01-31

    In this work, a method to determine the nitrogen content of nitrocellulose from gunpowders and collodions is proposed. A basic hydrolysis of nitrocellulose with 1.0% (m/v) NaOH at 150°C during 30 min was carried out for nitrocellulose from gunpowders (after its previous isolation by a protocol optimized by our research group) and from collodion samples. The concentration of nitrate and nitrite ions in the hydrolysate was determined by ion chromatography with suppression and conductimetric detection. The nitrogen content of nitrocellulose was calculated from the values of the concentration of both ions. The quantitative method was evaluated in terms of selectivity, sensitivity, robustness, limits of detection and quantification, and precision, measured as repeatability and intermediate precision. These parameters were good enough to demonstrate the validity of the method and its applicability to the determination of the nitrogen content of nitrocellulose contained in different types of gunpowders (single- and double-base gunpowders, manufactured from 1944 to 1997) and in commercial collodion samples. For gunpowders, the nitrogen content determined with the optimized method was compared with the values reported by the official label of the ammunition (obtained by a digestion/titration method) and errors, by defect, ranging from 1% to 15.2% (m/m) were calculated. The highest errors were obtained for the oldest gunpowders and could be attributed to the loss of nitro groups in the nitrocellulose molecule during aging. For collodion samples, errors could not be calculated since the real nitrogen content for these samples was not given in the label. In addition, the analysis time (2h for nitrocellulose isolation, 1.5h for nitrocellulose hydrolysis, and 0.2h for chromatographic separation) was about 10 times lower than in the digestion/titration method nowadays used for gunpowder samples. PMID:21168569

  4. Comparison of electrospray ionization and atmospheric pressure photoionization for coupling of micellar electrokinetic chromatography with ion trap mass spectrometry.

    PubMed

    Hommerson, Paul; Khan, Amjad M; de Jong, Gerhardus J; Somsen, Govert W

    2008-09-19

    The performance of dopant-assisted atmospheric pressure photoionization (DA-APPI) and electrospray ionization (ESI) for the coupling of micellar electrokinetic chromatography (MEKC) with ion trap mass spectrometry (ITMS) was compared using a set of test drugs comprising basic amines, steroids, esters, phenones and a quaternary ammonium compound. The influence of the surfactant sodium dodecyl sulfate (SDS) on analyte signals was studied by infusion of sample through the CE capillary into the respective ion sources. It was found that background electrolytes (BGEs) containing 20-50 mM SDS in 10 mM sodium phosphate (pH 7.5) caused major ionization suppression for both polar and apolar compounds in ESI-MS, whereas APPI-MS signal intensities remained largely unaffected. ESI gave rise to the formation of SDS clusters, which occasionally may cause space-charge effects in the ion trap. Furthermore, extensive sodium-adduct formation was observed for medium polar compounds with ESI-MS, whereas these compounds were detected as their protonated molecules with APPI-MS. Using the BGE containing 20 mM SDS, MEKC-ESI-MS still provides slightly lower limits of detection (LODs) (2.6-3.1 microM) than MEKC-APPI-MS (4.3-6.4 microM) for basic amines. For less polar compounds, highest S/Ns were obtained with APPI-MS detection (LODs, 4.5-71 microM). For BGEs containing 50 mM SDS, the limits of detection for MEKC-APPI-MS were more favorable (factor 1.5-12) than MEKC-ESI-MS for nearly all tested drugs. Spray shield contamination by SDS was lower in DA-APPI-MS than in ESI-MS. It is concluded that DA-APPI shows the most favorable characteristics for MEKC-MS, especially when compounds of low polarity have to be analyzed. PMID:18452927

  5. Dye-ligand and immobilized metal ion interaction chromatography for the purification of enzymes of prenyl pyrophosphate metabolism.

    PubMed

    Lanznaster, N; Croteau, R

    1991-02-01

    Dye-ligand and immobilized metal ion interaction chromatography were shown to be efficient techniques for the rapid batchwise fractionation, from crude plant extracts, of a series of enzymes of prenyl pyrophosphate metabolism. Isopentenyl pyrophosphate isomerase, two prenyltransferases, and a number of terpene cyclases (synthases) were readily adsorbed to Matrex Gel Red A (a dimeric triazine dye coupled to cross-linked agarose beads), and desorbed in good yield with relatively high concentrations of KCl and increasing pH. Although all of these enzymes exhibit the common feature of employing a pyrophosphorylated substrate, selective elution could not be achieved with substrate or substrate analogues bearing a pyrophosphate function. Nor could the strong binding of these enzymes to triazine dyes be attributed solely to metal ion interactions or to hydrophobic effects. In a similar way, the isomerase, the prenyltransferases, and all of the terpene cyclases bound to a column of iminodiacetate-immobilized Ni(II) and were desorbed in relatively high fold purity with 15 mM imidazole. Although all of these enzymes bear accessible histidine residues, the interactions with the chelated metal ion were not sufficiently different to permit selective enzyme desorbtion by imidazole gradient elution. However, the use of columns charged with Zn(II) or Co(II) did allow some separation of the different cyclase and transferase types. While empirical in nature, these techniques offer simple, effective, and high-capacity methods for the preliminary concentration and purification of a group of enzymes that utilize prenyl pyrophosphate intermediates of isoprenoid biosynthesis. PMID:1821775

  6. Neutral Loss Ion Mapping Experiment Combined with Precursor Mass List and Dynamic Exclusion for Screening Unstable Malonyl Glucoside Conjugates.

    PubMed

    Yang, Min; Zhou, Zhe; Yao, Shuai; Li, Shangrong; Yang, Wenzhi; Jiang, Baohong; Liu, Xuan; Wu, Wanying; Qv, Hua; Guo, De-an

    2016-01-01

    Malonates are one type of the acylation conjugates and found abundantly in ginseng and soybean. Malonyl conjugates of ginsenosides and isoflavone glycosides were often considered as the characteristic components to evaluate various species and different forms of ginseng and soybean products because of their thermal instability. Another famous isoflavonoid-rich leguminous traditional Chinese medicine (TCM), named Puerarin lobata (Gegen), has also been reported to contain malonyl daidzin and malonyl genistin. However, the conjugates were found to present in very low amount and particularly unstable in the negative ion mode scan using LTQ Orbitrap mass spectrometry with electrospray ionization (ESI). In order to screen and characterize the malonyl conjugates in Gegen, a specific method was designed and developed combining neutral loss ion mapping (NLIM) experiment and precursor mass list (PL) triggered data dependent acquisition (DDA). Along with the activation of dynamic exclusion (DE), the method was proven to be specific and efficient for searching the malonate derivatives from Gegen. Two samples were examined by the established method. A total of 66 compounds were found, and 43 of them were malonates of isoflavone glycoside. Very few compounds were reported previously in Gegen. The results are helpful to understand the constituents of Gegen with more insight. The study not only provided a method for analyzing the malonyl conjugates from complex matrices but also explored a way to trace other low amount components in TCMs. PMID:26334988

  7. Neutral Loss Ion Mapping Experiment Combined with Precursor Mass List and Dynamic Exclusion for Screening Unstable Malonyl Glucoside Conjugates

    NASA Astrophysics Data System (ADS)

    Yang, Min; Zhou, Zhe; Yao, Shuai; Li, Shangrong; Yang, Wenzhi; Jiang, Baohong; Liu, Xuan; Wu, Wanying; Qv, Hua; Guo, De-an

    2016-01-01

    Malonates are one type of the acylation conjugates and found abundantly in ginseng and soybean. Malonyl conjugates of ginsenosides and isoflavone glycosides were often considered as the characteristic components to evaluate various species and different forms of ginseng and soybean products because of their thermal instability. Another famous isoflavonoid-rich leguminous traditional Chinese medicine (TCM), named Puerarin lobata (Gegen), has also been reported to contain malonyl daidzin and malonyl genistin. However, the conjugates were found to present in very low amount and particularly unstable in the negative ion mode scan using LTQ Orbitrap mass spectrometry with electrospray ionization (ESI). In order to screen and characterize the malonyl conjugates in Gegen, a specific method was designed and developed combining neutral loss ion mapping (NLIM) experiment and precursor mass list (PL) triggered data dependent acquisition (DDA). Along with the activation of dynamic exclusion (DE), the method was proven to be specific and efficient for searching the malonate derivatives from Gegen. Two samples were examined by the established method. A total of 66 compounds were found, and 43 of them were malonates of isoflavone glycoside. Very few compounds were reported previously in Gegen. The results are helpful to understand the constituents of Gegen with more insight. The study not only provided a method for analyzing the malonyl conjugates from complex matrices but also explored a way to trace other low amount components in TCMs.

  8. Modeling of ion-pairing effect in peptide reversed-phase chromatography.

    PubMed

    Gétaz, David; Hariharan, Subrahmaniam B; Butté, Alessandro; Morbidelli, Massimo

    2012-08-01

    The modeling of counterion and organic modifier concentration effects in peptide APIs reversed-phase preparative chromatography is discussed in this manuscript. A stoichiometric retention model based on the counterion binding to the charged functional groups of the peptide is proposed. The model parameters were evaluated using a rather large set of retention data measured in mobile phases with various counterions and acetonitrile concentrations. The model parameters were experimentally validated by a new counterion binding measurement technique. The n(max) model parameter value was found to be equal to the peptide net charge, whereas the K model parameter value was found to be specific to the counterion type (i.e. AcO(-)

  9. Miniaturized GC/MS instrumentation for in situ measurements: micro gas chromatography coupled with miniature quadrupole array and paul ion trap mass spectrometers

    NASA Technical Reports Server (NTRS)

    Holland, P.; Chutjian, A.; Darrach, M.; Orient, O.

    2002-01-01

    Miniaturized chemical instrumentation is needed for in situ measurements in planetary exploration and other spaceflight applications where factors such as reduction in payload requirements and enhanced robustness are important. In response to this need, we are 'continuing to develop miniaturized GC/MS instrumentation which combines chemical separations by gas chromatography (GC) with mass spectrometry (MS) to provide positive identification of chemical compounds in complex mixtures of gases, such as those found in the International Space Station's cabin atmosphere. Our design approach utilizes micro gas chromatography components coupled with either a miniature quadrupole mass spectrometer array (QMSA) or compact, high-resolution Paul ion trap.

  10. Two-step ion-exchange chromatographic purification combined with reversed-phase chromatography to isolate C-peptide for mass spectrometric analysis.

    PubMed

    Kabytaev, Kuanysh; Durairaj, Anita; Shin, Dmitriy; Rohlfing, Curt L; Connolly, Shawn; Little, Randie R; Stoyanov, Alexander V

    2016-02-01

    A liquid chromatography with mass spectrometry on-line platform that includes the orthogonal techniques of ion exchange and reversed phase chromatography is applied for C-peptide analysis. Additional improvement is achieved by the subsequent application of cation- and anion-exchange purification steps that allow for isolating components that have their isoelectric points in a narrow pH range before final reversed-phase mass spectrometry analysis. The utility of this approach for isolating fractions in the desired "pI window" for profiling complex mixtures is discussed. PMID:26717885

  11. Characterization and Application of an Ambient Ion Monitor - Ion Chromatography (AIM-IC) System for the Detection of HONO and Nitrite in Polluted Environments

    NASA Astrophysics Data System (ADS)

    Vandenboer, T. C.; Markovic, M. Z.; Czar, M.; Murphy, J. G.

    2008-12-01

    The photolysis of the atmospheric trace gas nitrous acid (HONO) has been implicated as a major source of the OH radical, especially in early morning hours. While this rapid photolysis is expected to drive HONO concentrations to nearly zero during the day, significant concentrations have been observed in a variety of environments, indicating unknown or underestimated daytime sources. However, chemical interferences and lack of instrumental sensitivity make quantification of ambient HONO a true analytical challenge. During the Border Air Quality Study (BAQS) in 2007 near Harrow, ON observations frequently indicated low but non-zero mixing ratios of HONO and the presence of comparable amounts of particulate nitrite. Online, automated analysis of trace gases and PM2.5 constituents, was accomplished using Ambient Ion Monitor Ion Chromatography (AIM-IC) with collection by means of a parallel plate denuder and super saturated steam particle condensation chamber. The system was operated with one hour time resolution and was capable of characterizing 16 analyte ions. Subsequent method characterization yielded detection limits of 0.012 μg/m3 for particulate NO2- and 10 ppt for HONO by the isocratic elution methodology used in the Harrow field study. Laboratory experiments following this field campaign show that the collection efficiency of these species presented a source of uncertainty in observations of these trace gases. Interferences due to the presence of high NOX have also been explored. The method has since been used to characterize the effectiveness of particulate and gaseous collection between impactor and cyclone inlet assemblies. Finally, the optimized analytical system has been used to make measurements of HONO and nitrite in an urban setting in Toronto, ON.

  12. High performance ion chromatography of transition metal chelate complexes and aminopolycarboxylate ligands.

    PubMed

    Tófalvi, Renáta; Horváth, Krisztián; Hajós, Péter

    2013-01-11

    A simple ion chromatographic method was developed for the separation of transition metal chelates (CuEDTA, CuDCTA, ZnEDTA, ZnDCTA) and free anionic complexing ligands (EDTA, DCTA) using alkaline carbonate eluents and conductivity detection. The complex equilibria and kinetic process of separations were studied in order to understand major factors in the control of selectivity and retention order of complex anions. A systematic study was applied to identify the additional peaks of the system as NaEDTA(3-), NaHEDTA(2-), Na(2)EDTA(2-), EDTA(4-)/HEDTA(3-), DCTA(4-)/HDCTA(-3). On the basis of microequilibrium considerations of chelating ligand, it was shown that one should expect the peaks of sodium chelates when the ligand is in excess in the sample solution. The probability density function was introduced for calculation of complex chromatograms, because complexing ligands can exist in at least two different interconvertible forms in the presence of metal ion. The chromatogram of interconverting chelate species can be given as the sum of probability density functions (P) weighed by the molar fractions of complexed (Φ(ML)) and dissociated (Φ(L)) forms. The influences of kinetic rate of complex formation and dissociation on the distribution of components between eluents and ion exchange stationary phases were quantitatively described and demonstrated by elution profiles. The applicability of the developed method is represented by the simultaneous analysis of transition metal chelates and inorganic anions. ICP-AES analysis and FTIR-ATR technique were used for confirmation of IC results for metals and ligands, respectively. Collection protocols for the heart-cutting procedure of chromatograms were applied in the analysis of target components. The limit of detection and linearity of the method in the range of 0.01-0.25 mM sample concentration were also presented. PMID:23253118

  13. Permeative Amine Introduction for Very Weak Acid Detection in Ion Chromatography.

    PubMed

    Liao, Hongzhu; Dasgupta, Purnendu K

    2016-02-16

    A permeative amine introduction device (PAID) is placed after a conventional KOH eluent-suppressed conductometric anion chromatography (SCAC) system. The PAID converts the suppressed eluites from the acid form to the corresponding ammonium salt (NR2H + HX → NR2H2(+) + X(-)) and allows very weak acids HX (pKa ≥ 7.0) that cannot normally be detected by SCAC to be measured by a second conductivity detector following the PAID. Permeative reagent introduction is dilutionless, can be operated without pumps, and provides good mixing (baseline noise 0.8 nS/cm for 27 μM diethylamine) with low band dispersion (as small as 30 μL). Diethylamine (DEA) was chosen as the amine source due to its low pKb value (3.0), high vapor pressure, low toxicity, and low odor. The eluites are thus detected against a low diethylammonium hydroxide (DEAOH) background (5-31 μS/cm) as negative peaks because the equivalent conductance of OH(-) is greater than that of X(-). Reducing the background DEA concentration enhances the detectability of traces of weak acids. Lower background [DEA] will limit the maximum concentration of analyte acids that can be determined; a general concept of peak width measurement at a fixed height is proposed as a solution. Trace impurities formed during electrodialytic suppression play a role in background noise; for the first time, we look at the nature of such impurities. The appearance of silicate in a sample put in a glass container as a function of pH can be readily followed. The maximum silica level in high purity type 1 water is 50 nM (1.40 μg/L Si), which is a measurement challenge in particular. A large injection volume (1 mL) permits detection limits of 21 nM silicate, 3 nM taurine, 3 nM sulfide, and 13 nM cyanide. PMID:26815767

  14. Semiautomated pH gradient ion-exchange chromatography of monoclonal antibody charge variants.

    PubMed

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

    2014-10-01

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

  15. [Analysis of toxaphene and its eight congeners in sediment and fish tissue by gas chromatography-negative ion mass spectrometry].

    PubMed

    Lao, Wenjian

    2013-07-01

    Toxaphene quantification incorporating gas chromatography/negative chemical ionization mass spectrometry (GC/NCI-MS) offers improved sensitivity and specificity. The U. S. Environmental Protection Agency (USEPA) recently released a GC/NCI-MS method (Method 8276) for the measurement of technical toxaphene and eight specific congeners (Hx-Sed, Hp-Sed, P26, P41, P40, P44, P50 and P62). However, there is still lack of a practical and complete analytical method including sample extraction, clean up, instrumental analysis, and data analysis. The goal of this work was to develop a ready-to-use method for the quantification of total toxaphene and the eight congeners. Sediment and salmon fish tissue were selected as sample matrices and extracted with methylene chloride using an accelerated solvent extraction system. The sample extracts were cleaned up with active copper powder or gel permeation chromatography, and finally silica/alumina combination column. Separation was performed on a DB-XLB column. GC/NCI-MS was operated under selected ion monitoring mode with an identical set of confirmation and quantitation ions for total toxaphene and the eight congeners. Oxygen reaction of polychlorinated biphenyls (PCB) was monitored by PCB204, an internal calibration standard, and the reaction level was kept below 1%. Average relative response factors were used in quantitation. Quantitation of total toxaphene employed the sum of all detectable (S/N > or = 3) 6-C1 to 10-Cl homolog peak areas, while the individual congeners were quantified followed the standard procedures for single analytes. Multi-point calibration solutions ranged from 0. 5 (5 for P62) to 500 microg/L for the individual congeners, and 50 to 500 microg/L for technical toxaphene, with the lowest calibration levels as lower limits of quantitation. Average congener recovery was (90.8 +/- 17.4)% (n =10) in spiked sediment with relative standard deviations of 5.4% - 12.8% (n =10), underscoring an excellently accurate and precise method. The method was applied to analyze sediment and fish tissue sample. PMID:24164036

  16. Ion pair liquid chromatography method for the determination of thiamine (vitamin B1) homeostasis.

    PubMed

    Basiri, Babak; Sutton, James Michael; Hanberry, Bradley S; Zastre, Jason A; Bartlett, Michael G

    2016-01-01

    A new method for reversed phase HPLC determination of thiamine and its major in vivo phosphorylation products, thiamine monophosphate (TMP) and thiamine pyrophosphate (TPP), was developed using tetrabutylammonium hydroxide as the ion-pairing agent. The separation was performed on a Phenomenex Kinetex EVO C18 column with a gradient of a phosphate-buffered aqueous solution of the ion-pair reagent and methanol. The duty cycle for the assay was 13 min and pyrithiamine was successfully used as the internal standard for the first time in a thiamine HPLC measurement protocol. Detection of the fluorescence derivatives of the analytes as well as the IS allowed for lower detection limits in order to support biological applications in cell culture models. The linearity, sensitivity, specificity, accuracy and precision of the method were evaluated and met the requirements specified by the US Food and Drug Administration. The calibration curves proved to be linear and the method was validated over the range from 1.0-4000 nm for both cells and the media where complete recovery of the analytes was also achieved. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26120008

  17. Efficient purification of small unsaturated oligoglucuronides by reversed-phase chromatography.

    PubMed

    Tavernier, Marie-Laure; Petit, Emmanuel; Lesur, David; Wadouachi, Anne; Courtois, Bernard; Courtois, Josiane; Michaud, Philippe

    2008-03-01

    Ion-exchange chromatography has been applied to purification of unsaturated oligoglucuronans. After an isocratic elution on a strong anion-exchange column, the collected fractions were desalted by low pressure size exclusion chromatography. However, this efficient separation was limited by the time required to desalt. So, we developed a reversed-phase chromatography method using back ionization of oligomers. Two C18 columns were tested with trifluoroacetic acid (TFA 0.7%) as eluent. Different selectivities and column stabilities were observed in this acidic condition. The scale up for semi-preparative applications enabled us to recover pure unsaturated oligoglucuronans without desalting step. PMID:18262480

  18. Capillary ion chromatography with on-column focusing for ultra-trace analysis of methanesulfonate and inorganic anions in limited volume Antarctic ice core samples.

    PubMed

    Rodriguez, Estrella Sanz; Poynter, Sam; Curran, Mark; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Paull, Brett

    2015-08-28

    Preservation of ionic species within Antarctic ice yields a unique proxy record of the Earth's climate history. Studies have been focused until now on two proxies: the ionic components of sea salt aerosol and methanesulfonic acid. Measurement of the all of the major ionic species in ice core samples is typically carried out by ion chromatography. Former methods, whilst providing suitable detection limits, have been based upon off-column preconcentration techniques, requiring larger sample volumes, with potential for sample contamination and/or carryover. Here, a new capillary ion chromatography based analytical method has been developed for quantitative analysis of limited volume Antarctic ice core samples. The developed analytical protocol applies capillary ion chromatography (with suppressed conductivity detection) and direct on-column sample injection and focusing, thus eliminating the requirement for off-column sample preconcentration. This limits the total sample volume needed to 300μL per analysis, allowing for triplicate sample analysis with <1mL of sample. This new approach provides a reliable and robust analytical method for the simultaneous determination of organic and inorganic anions, including fluoride, methanesulfonate, chloride, sulfate and nitrate anions. Application to composite ice-core samples is demonstrated, with coupling of the capillary ion chromatograph to high resolution mass spectrometry used to confirm the presence and purity of the observed methanesulfonate peak. PMID:26206628

  19. Theoretical evaluation of peak capacity improvements by use of liquid chromatography combined with drift tube ion mobility-mass spectrometry.

    PubMed

    Causon, Tim J; Hann, Stephan

    2015-10-16

    In the domain of liquid phase separations, the quality of separation obtainable is most readily gauged by consideration of classical chromatographic peak capacity theory. Column-based multidimensional strategies for liquid chromatography remain the most attractive and practical route for increasing the number of spatially resolved components in order to reduce stress on necessary mass spectrometric detection. However, the stress placed on a chromatographic separation step as a second dimension in a comprehensive online methodology (i.e. online LC×LC) is rather high. As an alternative to online LC×LC combinations, coupling of HPLC with ion mobility spectrometry hyphenated to mass spectrometry (IMS-MS) has emerged as an attractive approach to permit comprehensive sampling of first dimension chromatographic peaks and subsequent introduction to an orthogonal IMS separation prior to measurement of ions by a mass spectrometer. In the present work, utilization of classical peak capacity and ion mobility theory allows theoretical assessment of the potential of two- (LC×IMS-MS) or even three-dimensional (LC×LC×IMS-MS) experimental setups to enhance peak capacity and, therefore, the number of correctly annotated features within the framework of complex, non-targeted analysis problems frequently addressed using HPLC-MS strategies. Theoretical calculations indicate that newly-available drift tube IMS-MS instrumentation can yield peak capacities of between 10 and 40 using nitrogen drift gas for typical non-targeted metabolomic, lipidomic and proteomic applications according to the expected reduced mobilities of components in the respective samples. Theoretically, this approach can significantly improve the overall peak capacity of conventional HPLC-(MS) methodologies to in excess of 10(4) depending upon the column length and gradient time employed. A more elaborate combination of LC×LC×IMS-MS would improve the ion suppression limitation and possibly allow access to theoretically even higher peak capacities, but such a combination may render the IMS separation practically redundant as well as imparting the well-known dilution problems associated with LC×LC. Finally, some predictions for the separation of co-eluted isobaric compounds can also be made by considering the required peak-to-peak resolution for acceptable IMS separation. The here-described theoretical predication approach can be used to aid method development for HPLC×IMS-MS and is also accompanied by some practical considerations that should be contemplated in associated non-targeted analysis workflows. PMID:26372446

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

    USGS Publications Warehouse

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

    1983-01-01

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

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

    PubMed

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

    2013-12-01

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

  2. Quantitative trace-level speciation of arsenite and arsenate in drinking water by ion chromatography.

    PubMed

    Johnson, Rebecca L; Aldstad, Joseph H

    2002-10-01

    We describe an improved method for the determination of inorganic arsenic in drinking water. The method is based on comprehensive optimization of the anion-exchange ion chromatographic (IC) separation of arsenite and arsenate with post-column generation and detection of the arsenate-molybdate heteropoly acid (AMHPA) complex ion. The arsenite capacity factor was improved from 0.081 to 0.13 by using a mobile phase (2.0 mL min(-1)) composed of 2.5 mM Na2CO3 and 0.91 mM NaHCO3 (pH 10.5). A post-column photo-oxidation reactor (2.5 m x 0.7 mm) was optimized (0.37 microM potassium persulfate at 0.50 mL min(-1)) such that arsenite was converted to arsenate with 99.8 +/- 4.2% efficiency. Multi-variate optimization of the complexation reaction conditions yielded the following levels: 1.3 mM ammonium molybdate, 7.7 mM ascorbic acid, 0.48 M nitric acid, 0.17 mM potassium antimony tartrate, and 1.0% (v/v) glycerol. A long-path length flow cell (Teflon AF, 100-cm) was used to measure the absorption of the AMHPA complex (818 +/- 2 nm). Figures of merit for arsenite/arsenate include: limit of detection (1.6/0.40 microg L(-1)): standard error in absorbance (5.1 x 10(-3)/3.5 x 10(-3)); and sensitivity (2.9 x 10(-3)/2.2 x 10(-3) absorbance units per ppb). Successful application of the method to fortified surface and ground waters (100 microL samples) is also described. PMID:12430600

  3. Analysis of inorganic nitrogen and related anions in high salinity water using ion chromatography with tandem UV and conductivity detectors.

    PubMed

    Wilson, Brian; Gandhi, Jay; Zhang, Chunlong Carl

    2011-09-01

    Over 97% of the Earth's water is high salinity water in the form of gulfs, oceans, and salt lakes. There is an increasing concern for the quality of water in bays, gulfs, oceans, and other natural waters. These waters are affected by many different sources of contamination. The sources are, but not limited to, groundwater run-off of nitrogen containing fertilizer, pesticides, cleaning agents, solid wastes, industrial waters, and many more. The final destinations of these contaminants are rivers, lakes, and bayous that eventually will lead to bays, gulfs, and oceans. Many industries depend on the quality of these waters, such as the fishing industry. In addition to wild marine life, there are large aquariums and fish and shrimp farms that are required to know the quality of the water. However, the ability of these industries to monitor their processes is limited. Most analytical methods do not apply to the analysis of high salinity waters. They are dependent on wet chemistry techniques, spectrophotometers, and flow analyzers. These methods do not have the accuracy, precision, and sensitivity when compared to ion chromatography (IC). Since the inception of IC, it has become a standard practice for determining the content of many different water samples. Many IC methods are limited in the range of analytes that can be detected, as well as the numerous sample sources of which the methods are applicable. The main focus of current IC methods does not include high salinity waters. This research demonstrates an ion chromatographic method that has the ability to determine low level concentrations of inorganic nitrogen and related anions (nitrite-N, nitrate-N, phosphorous-P, sulfate, bromide, chloride, sulfide, fluoride, ammonia, calcium, and magnesium) in a single run using a combination of UV and conductivity detectors. This method is applicable to various waters, and uses both freshwater and high salinity water samples. PMID:21859532

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

    PubMed

    Guyon, Francois; Gaillard, Laetitia; Brault, Audrey; Gaultier, Nicolas; Salagoty, Marie-Hlne; Mdina, Bernard

    2013-12-27

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

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

    PubMed

    Jerz, Gerold; Skotzki, Tanja; Fiege, Kathrin; Winterhalter, Peter; Wybraniec, Sławomir

    2008-05-01

    The first preparative fractionation of betalain pigments by means of ion-pair high-speed counter-current chromatography (IP-HSCCC) from berry extracts of Phytolacca americana (Phytolaccaceae) is presented. A novel HSCCC solvent system consisting of 1-butanol-acetonitrile-water (5:1:6, v/v/v) was applied using ion-pair forming trifluoroacetic acid at low concentration (0.7%, v/v). Affinity of polar betacyanins and betaxanthins to the organic stationary phase of the biphasic HSCCC solvent mixture was considerably improved. Partitioning coefficient values and influence of increasing trifluoroacetic acid additions to the biphasic solvent mixture were measured for all identified betacyanins and betaxanthins. Gentle separation by IP-HSCCC of the injected pigment extract (900 mg) yielded sufficient amounts of the principal pigments 15S-betanin/15R-isobetanin. The pure epimers separated by C18-HPLC were immediately studied by one- and two-dimensional NMR. In the recovered fractions, minor concentrated betacyanins and betaxanthins were significantly enriched by IP-HSCCC and were detected for the first time in the extracts of P. americana. IP-HSCCC and C18-HPLC were shown to be complementary techniques in the isolation procedure of recovering minor concentrated, highly polar and chemically instable betacyanins and betaxanthin from complex plant matrices. Altogether, identification of 17 betalains was achieved by HPLC-diode array detection-electrospray ionization MS/MS in the HSCCC fractions with their respective isomers, also resulting in the tentative elucidation of betacyanins with novel salicylic acid substitution pattern in the berry extracts of P. americana. PMID:18374932

  6. Determination of phenols with ion chromatography-online electrochemical derivatization based on porous electrode-fluorescence detection.

    PubMed

    Wu, Shuchao; Yang, Bingcheng; Xi, Lingling; Zhu, Yan

    2012-03-16

    The current study describes the determination of phenols using ion chromatography-online electrochemical derivatization-fluorescence detection (IC/ED/FD). Six model phenols including 4-methylphenol (pMP), 2, 4-dimethylphenol (DMP), 4-tert-butylphenol (TBP), 4-hydroxylphenolacetic acid (pHPA), 4-acetamidophenol (pAAP), and phenol (P) were well separated on an anion-exchange column under ion exchange mode using NaOH with small amount of acetonitrile added as eluent. Online electrochemical derivatization performed via a laboratory-made electrolytic cell (EC), consisting of porous titanium electrode and cation-exchange membrane (CEM), allows the oxidation products that are strongly fluorescent to be detected by the fluorescence detector. NaOH eluent used in the present method matches well with the maximal fluorescence intensity obtained at alkaline condition for oxidized phenols, thus the addition of specific buffer solution after oxidation encountered in previous report could be eliminated. This process leads to a simplified procedure. The proposed method was sensitive to the limits of detection in the range of 0.4 μg/L and 3.8 μg/L and the limits of quantification between 1.2 μg/L and 13 μg/L due to the strong electro-oxidation capacity of porous titanium electrode, as well as the implementation of time-programmed potential over EC. The linear ranges were 2.0-1.0 × 10(4) μg/L for pAAP and DMP, and 10-1.0 × 10(4) μg/L for P, pMP, pHPA, and TBP, respectively. The relative standard deviations range from 0.9% to 4.8%. The utilization of the method was demonstrated by the analysis of real samples. The average spiked recoveries of target analytes in pool water were 81.0-118%. PMID:22305361

  7. Recovering Paleo-Records from Antarctic Ice-Cores by Coupling a Continuous Melting Device and Fast Ion Chromatography.

    PubMed

    Severi, Mirko; Becagli, Silvia; Traversi, Rita; Udisti, Roberto

    2015-11-17

    Recently, the increasing interest in the understanding of global climatic changes and on natural processes related to climate yielded the development and improvement of new analytical methods for the analysis of environmental samples. The determination of trace chemical species is a useful tool in paleoclimatology, and the techniques for the analysis of ice cores have evolved during the past few years from laborious measurements on discrete samples to continuous techniques allowing higher temporal resolution, higher sensitivity and, above all, higher throughput. Two fast ion chromatographic (FIC) methods are presented. The first method was able to measure Cl(-), NO3(-) and SO4(2-) in a melter-based continuous flow system separating the three analytes in just 1 min. The second method (called Ultra-FIC) was able to perform a single chromatographic analysis in just 30 s and the resulting sampling resolution was 1.0 cm with a typical melting rate of 4.0 cm min(-1). Both methods combine the accuracy, precision, and low detection limits of ion chromatography with the enhanced speed and high depth resolution of continuous melting systems. Both methods have been tested and validated with the analysis of several hundred meters of different ice cores. In particular, the Ultra-FIC method was used to reconstruct the high-resolution SO4(2-) profile of the last 10,000 years for the EDML ice core, allowing the counting of the annual layers, which represents a key point in dating these kind of natural archives. PMID:26494022

  8. [Determination of total cyanides and sulfides in wastewater using ion chromatography coupled with ultraviolet photo-dissociation/gas-membrane diffusion].

    PubMed

    Lu, Keping

    2015-03-01

    An automated system for the determination of total cyanides and sulfides in wastewater has been developed using flow injection, ultraviolet (UV) photo-dissociation, gas-membrane diffusion, column trapping, ion chromatography separation and pulsed amperometric detection. When the sample was mixed with sulfuric acid and hypophosphorous acid medium containing the appropriate amount of sulfamic acid, ascorbic acid, EDTA and citric acid, metal-cyanide complexes such as Fe (CN)3-(6) can be photo-dissociated by 312 nm UV light, which results in hydrogen cyanide ( HCN) and similarly, sulfides release hydrogen sulfide (H2S). These products were diffused through a 0.45 m hydrophobic porous polypropylene membrane and were then absorbed in the dilute NaOH solution, concentrated with a Metrosep A PCC 1 HC/4.0 column, separated on an IonPac AS7 column, and finally detected by the pulsed amperometric detector with Ag electrode. The total cyanides and sulfides were good linear in the range of 0.5-1,000 g/L with correlation coefficients of 0.998 9 and 0.999 7 respectively. The recoveries were 93%-102% and the limits of detection were 0.5 g/L for total cyanides and 1.0 g/L for sulfides under the conditions of the sample volume of 100 L and the signal to noise ratio of 5. The sample throughput of the system was six samples per hour. The results from this new method have been compared with the ones obtained with the standard method, which shows a good agreement. PMID:26182472

  9. The Use of Ion Chromatography for the Determination of Clean-In-Place-200 (CIP-200) Detergent Traces

    PubMed Central

    Resto, Wilfredo; Roque, Joan; Rey, Rosamil; Colón, Héctor; Zayas, José

    2006-01-01

    Anion chromatography with conductivity detection was chosen as the analytical technique for the development of a cleaning validation method for clean-in-place (CIP) detergents. The method was developed and validated for the determination of traces of the detergent CIP-200. It was shown to be linear with a squared correlation coefficient (r2) of 0.9999 and the accuracy experiments presented average recoveries of 88.2% (area response factor) from stainless steel surfaces. The repeatability was found to be 1.6% and an intermediate precision of 1.9% across the range. The method was also shown to be sensitive with an average Detection Limit (DL) of 0.23 ppm and a Quantitation Limit (QL) of 0.70 ppm based on the amount of phosphate in the detergent sample. The phosphate signal was well resolved from typical ions encountered in water samples or any other interference presented from swabs and surfaces. The method was applied to cleaning validation samples and proved to be suitable for rapid and reliable quality control. PMID:19690632

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

    PubMed

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

    2014-10-01

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

  11. Determination of L-carnitine in food supplement formulations using ion-pair chromatography with indirect conductimetric detection.

    PubMed

    Kakou, Aikaterini; Megoulas, Nikolaos C; Koupparis, Michael A

    2005-04-01

    A novel method for the determination of L-carnitine in food supplement formulations was developed and validated, using ion-pair chromatography with indirect conductimetric detection. The chromatographic method was based on a non-polar (C18) column and an aqueous octanesulfonate (0.64 mM) eluent, acidified with trifluoroacetic acid (5.2 mM). The retention time was 5.4 min and the asymmetry factor 0.65. A linear calibration curve from 10 to 1000 microg/ml (r= 0.99998), with a detection limit of 2.7 microg/ml (25 microl injection volume), a repeatability %RSD of 0.8 (40 microg/ml, n = 5) and reproducibility %RSD of 2.6 were achieved. The proposed method was applied for the determination of carnitine in oral solutions and capsules. No interference from excipients was found and the only pretreatment step required was the appropriate dilution with the mobile phase. Recovery from spiked samples was ranged from 97.7 to 99.7% with a precision (%RSD, n = 3) of 0.01-2.1%. PMID:15830947

  12. Direct Separation of Molybdenum from Solid Uranium Matrices Employing Pyrohydrolysis, a Green Separation Method, and Its Determination by Ion Chromatography.

    PubMed

    Mishra, Vivekchandra G; Thakur, Uday K; Shah, Dipti J; Gupta, Neeraj K; Jeyakumar, Subbiah; Tomar, Bhupendra S; Ramakumar, Karanam L

    2015-11-01

    Pyrohydrolysis is a well-established separation method, and it is being used as a sample preparation method for several materials for further determination of non-metals such as halogens, boron, and sulfur. Analytes are retained in a diluted solution that is suitable for carrying out analysis by several determination techniques and minimizing the use of concentrated reagents. Pyrohydrolysis separation of metals has not been reported yet. The present study demonstrates the pyrohydrolysis separation of Mo as MoO4(2-) from uranium materials and its subsequent determination using ion chromatography coupled with suppressed conductivity detector. With use of TGA and XRD the volatilization behavior of Mo was studied. Important parameters for the pyrohydrolysis method required for the quantitative separation of Mo were evaluated. The precision of the method was better than 5% at 25 ppm of Mo. The accuracy was evaluated by analysis of a CRM (U3O8-ILCE-IV). The method was applied to determine Mo in ammonium diuranate samples, where the conventional methods suffer from the loss of Mo. PMID:26465172

  13. Simultaneous screening and confirmation of multiple classes of drug residues in fish by liquid chromatography-ion trap mass spectrometry.

    PubMed

    Smith, Shani; Gieseker, Charles; Reimschuessel, Renate; Decker, Christie-Sue; Carson, Mary C

    2009-11-13

    LC-ion trap mass spectrometry was used to screen and confirm 38 compounds from a variety of drug classes in four species of fish: trout, salmon, catfish, and tilapia. Samples were extracted with acetonitrile and hexane. The acetonitrile phase was evaporated, redissolved in water and acetonitrile, and analyzed by gradient chromatography on a phenyl column. MS(2) or MS(3) spectra were monitored for each compound. Qualitative method performance was evaluated by the analysis over several days of replicate samples of control fish, fish fortified with a drug mixture at 1 ppm, 0.1 ppm and 0.01 ppm, and fish dosed with a representative from each drug class. Half of the 38 drugs were confirmed at 0.01 ppm, the lowest fortification level. This included all of the quinolones and fluoroquinolones, the macrolides, malachite green, and most of the imidazoles. Florfenicol amine, metronidazole, sulfonamides, tetracyclines, and most of the betalactams were confirmed at 0.1 ppm. Ivermectin and penicillin G were only detectable in the 1 ppm fortified samples. With the exception of amoxicillin, emamectin, metronidazole, and tylosin, residue presence was confirmed in all the dosed fish. PMID:19616215

  14. Determination of malachite green and leucomalachite green in edible goldfish muscle by liquid chromatography-ion trap mass spectrometry.

    PubMed

    Lee, Kim-Chung; Wu, Jian-Lin; Cai, Zongwei

    2006-11-01

    A liquid chromatography-ion trap mass spectrometry method with three "time segments" has been developed to determine malachite green (MG) and its major metabolite, leucomalachite green (LMG) in edible goldfish muscle. By using the optimized "time segments", MG and LMG as well as the internal standard atrazine-d(5) were analyzed with good sensitivity with positive ESI-MS in a single run. The homogenized fish muscle tissues were extracted with a solution of perchloric acid and acetonitrile, followed by partitioning with dichloromethane. Strata-x polymeric solid-phase extraction column was used for the clean-up process. The determination of MG and LMG was achieved by using a reversed-phase HPLC gradient program coupled with MS/MS in multiple-reaction-monitoring mode. Matrix calibration curves were linear over the ranges of 5-500 ng/ml for MG and 1-100 ng/ml for LMG. Recoveries of the fish tissue extraction at three spiked levels (2, 10 and 30 ng/g for MG as well as 0.4, 2 and 6 ng/g for LMG) were better than 71% and 89%, respectively. Relative standard derivations from six determinations were less than 8%. The method detection limits were 0.13 ng/g for MG and 0.06 ng/g for LMG. PMID:16824810

  15. Development of an Ion Chromatography Method for Analysis of Organic Anions (Fumarate, Oxalate, Succinate, and Tartrate) in Single Chromatographic Conditions

    PubMed Central

    Kaviraj, Yarbagi; Srikanth, B.; Moses Babu, J.; Venkateswara Rao, B.; Paul Douglas, S.

    2015-01-01

    A single organic counterion analysis method was developed by using an ion chromatography separation technique and conductivity detector. This allows the rapid characterization of an API to support clinical studies and to fulfil the regulatory requirements for the quantitation of fumarate, oxalate, succinate, and tartrate counterions in active pharmaceutical ingredients (quetiapine fumarate, escitalopram oxalate, sumatriptan succinate, and tolterodine tartrate). The method was developed by using the Metrohm Metrosep A Supp 1 (250 × 4.0 mm, 5.0 µm particle size) column with a mobile phase containing an isocratic mixture of solution A: 7.5 mM sodium carbonate and 2.0 mM sodium bicarbonate in Milli-Q water and solution B: acetonitrile. The flow rate was set at 1.0 mL/min and the run time was 25 minutes. The developed method was validated as per ICH guidelines, and the method parameters were chosen to ensure the spontaneous quantitation of all four anions. The method was validated for all four anions to demonstrate the applicability of this method to common anions present in various APIs. PMID:26839842

  16. Development of an Ion Chromatography Method for Analysis of Organic Anions (Fumarate, Oxalate, Succinate, and Tartrate) in Single Chromatographic Conditions.

    PubMed

    Kaviraj, Yarbagi; Srikanth, B; Moses Babu, J; Venkateswara Rao, B; Paul Douglas, S

    2015-01-01

    A single organic counterion analysis method was developed by using an ion chromatography separation technique and conductivity detector. This allows the rapid characterization of an API to support clinical studies and to fulfil the regulatory requirements for the quantitation of fumarate, oxalate, succinate, and tartrate counterions in active pharmaceutical ingredients (quetiapine fumarate, escitalopram oxalate, sumatriptan succinate, and tolterodine tartrate). The method was developed by using the Metrohm Metrosep A Supp 1 (250 × 4.0 mm, 5.0 µm particle size) column with a mobile phase containing an isocratic mixture of solution A: 7.5 mM sodium carbonate and 2.0 mM sodium bicarbonate in Milli-Q water and solution B: acetonitrile. The flow rate was set at 1.0 mL/min and the run time was 25 minutes. The developed method was validated as per ICH guidelines, and the method parameters were chosen to ensure the spontaneous quantitation of all four anions. The method was validated for all four anions to demonstrate the applicability of this method to common anions present in various APIs. PMID:26839842

  17. Microscopic insight into role of protein flexibility during ion exchange chromatography by nuclear magnetic resonance and quartz crystal microbalance approaches.

    PubMed

    Hao, Dongxia; Ge, Jia; Huang, Yongdong; Zhao, Lan; Ma, Guanghui; Su, Zhiguo

    2016-03-18

    Driven by the prevalent use of ion exchange chromatography (IEC) for polishing therapeutic proteins, many rules have been formulated to summarize the different dependencies between chromatographic data and various operational parameters of interest based on statically determined interactions. However, the effects of the unfolding of protein structures and conformational stability are not as well understood. This study focuses on how the flexibility of proteins perturbs retention behavior at the molecular scale using microscopic characterization approaches, including hydrogen-deuterium (H/D) exchange detected by NMR and a quartz crystal microbalance (QCM). The results showed that a series of chromatographic retention parameters depended significantly on the adiabatic compressibility and structural flexibility of the protein. That is, softer proteins with higher flexibility tended to have longer retention times and stronger affinities on SP Sepharose adsorbents. Tracing the underlying molecular mechanism using NMR and QCM indicated that an easily unfolded flexible protein with a more compact adsorption layer might contribute to the longer retention time on adsorbents. The use of NMR and QCM provided a previously unreported approach for elucidating the effect of protein structural flexibility on binding in IEC systems. PMID:26896917

  18. Analytical characterization of complex, biotechnological feedstocks by pH gradient ion exchange chromatography for purification process development.

    PubMed

    Kröner, Frieder; Hanke, Alexander T; Nfor, Beckley K; Pinkse, Martijn W H; Verhaert, Peter D E M; Ottens, Marcel; Hubbuch, Jürgen

    2013-10-11

    The accelerating growth of the market for proteins and the growing interest in new, more complex molecules are bringing new challenges to the downstream process development of these proteins. This results in a demand for faster, more cost efficient, and highly understood downstream processes. Screening procedures based on high-throughput methods are widely applied nowadays to develop purification processes for proteins. However, screening highly complex biotechnological feedstocks, such as complete cell lysates containing target proteins often expressed with a low titre, is still very challenging. In this work we demonstrate a multidimensional, analytical screening approach based on pH gradient ion exchange chromatography (IEC), gel electrophoresis and protein identification via mass spectrometry to rationally characterize a biotechnological feedstock for the purpose of purification process development. With this very simple characterization strategy a two-step purification based on consecutive IEC operations was rapidly laid out for the purification of a diagnostic protein from a cell lysate reaching a purity of ∼80%. The target protein was recombinantly produced using an insect cell expression system. PMID:24016717

  19. Simple column-switching ion chromatography method for determining eight monosaccharides and oligosaccharides in honeydew and nectar.

    PubMed

    Ni, Chengzhu; Zhu, Binhe; Wang, Nani; Wang, Muhua; Chen, Suqing; Zhang, Jiajie; Zhu, Yan

    2016-03-01

    Honeydew is excreted by aphids as a sweet waste and nectar is floral honey. Honeydew and nectar are complicated samples which consist of various sugars and amino acids. In this work, a simple ion chromatography with column-switching method was developed for the simultaneous analysis of 8 monosaccharides and oligosaccharides in honeydew and nectar. A reversed-phase column was used as a pretreatment column to eliminate organics on-line and sugars were eluted from a collection loop to analytical column by using column-switching technique. This method showed good linearity (r⩾0.9994) and afforded low limits of detection ranging from 1.55 to 10.17μgL(-1) for all the analytes. Recoveries ranged from 95% to 105% and repeatability results were acceptable with relative standard deviation of less than 3.21% (n=6). This method was successfully applied to quantification of these sugars in honeydew and nectar. These results showed honeydew had much more oligosaccharides than nectar. PMID:26471592

  20. Multiple applications of ion chromatography oligosaccharide fingerprint profiles to solve a variety of sugar and sugar-biofuel industry problems.

    PubMed

    Eggleston, Gillian; Borges, Eduardo

    2015-03-25

    Sugar crops contain a broad variety of carbohydrates used for human consumption and the production of biofuels and bioproducts. Ion chromatography with integrated pulsed amperometric detection (IC-IPAD) can be used to simultaneously detect mono-, di-, and oligosaccharides, oligosaccharide isomers, mannitol, and ethanol in complex matrices from sugar crops. By utilizing a strong NaOH/NaOAc gradient method over 45 min, oligosaccharides of at least 2-12 dp can be detected. Fingerprint IC oligosaccharide profiles are extremely selective, sensitive, and reliable and can detect deterioration product metabolites from as low as 100 colony-forming units/mL lactic acid bacteria. The IC fingerprints can also be used to (i) monitor freeze deterioration, (ii) optimize harvesting methods and cut-to-crush times, (iii) differentiate between white refined sugar from sugar cane and from sugar beets, (iv) verify the activities of carbohydrate enzymes, (v) select yeasts for ethanol fermentations, and (vi) isolate and diagnose infections and processing problems in sugar factories. PMID:25708094

  1. Quantification of four arsenic species in fruit juices by ion-chromatography-inductively coupled plasma-mass spectrometry.

    PubMed

    Conklin, Sean D; Chen, Peter E

    2012-08-01

    A method using ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS) for the quantification of arsenic species in fruit juices has been developed and validated. The method is capable of quantifying four anionic arsenic species - arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) - in the presence of unretained species such as arsenobetaine (AsB). Method validation was based on repeatability, analysis of reference materials, recovery of fortified samples, and determination of detection and quantification limits. The method was tested for use with apple, pear, cranberry, grape (red, white and purple) juices, as well as several juice blends. Limits of detection were 0.35, 0.41, 0.45 and 0.70 µg kg⁻¹ for As(III), DMA, MMA and As(V), respectively. Chromatographic recovery was good for most samples (90-107% compared to total arsenic), though recovery for some grape juice samples was lower (67-78%). PMID:22639850

  2. In vitro metabolism of corydaline in human liver microsomes and hepatocytes using liquid chromatography-ion trap mass spectrometry.

    PubMed

    Ji, Hye Young; Lee, Hyeri; Kim, Jeong-Han; Kim, Ki Hyun; Lee, Kang Ro; Shim, Hyun Joo; Son, Miwon; Lee, Hye Suk

    2012-05-01

    Corydaline is a pharmacologically active isoquinoline alkaloid isolated from Corydalis tubers. It exhibits the antiacetylcholinesterase, antiallergic, antinociceptive, and gastric emptying activities. The purposes of this study were to establish in vitro metabolic pathways of corydaline in human liver microsomes and hepatocytes by identification of their metabolites using liquid chromatography-ion trap mass spectrometry. Human liver microsomal incubation of corydaline in the presence of an NADPH-generating system resulted in the formation of nine metabolites, namely, four O-desmethylcorydaline [M1 (yuanhunine), M2 (9-O-desmethylcorydaline), M3 (isocorybulbine), and M4 (corybulbine)], three di-O-desmethylcorydaline [M5 (9,10-di-O-desmethylcorydaline), M6 (2,10-di-O-desmethylcorydaline), and M7 (3,10-di-O-desmethylcorydaline)], M8 (hydroxyyuanhunine), and M9 (hydroxycorydaline). Incubation of corydaline in human hepatocytes produced four metabolites including M1, M5, M6, and M9. O-Demethylation and hydroxylation were the major metabolic pathways for the metabolism of corydaline in human liver microsomes and hepatocytes. PMID:22689485

  3. Optimization of Immobilized Gallium (III) Ion Affinity Chromatography for Selective Binding and Recovery of Phosphopeptides from Protein Digests

    PubMed Central

    Aryal, Uma K.; Olson, Douglas J.H.; Ross, Andrew R.S.

    2008-01-01

    Although widely used in proteomics research for the selective enrichment of phosphopeptides from protein digests, immobilized metal-ion affinity chromatography (IMAC) often suffers from low specificity and differential recovery of peptides carrying different numbers of phosphate groups. By systematically evaluating and optimizing different loading, washing, and elution conditions, we have developed an efficient and highly selective procedure for the enrichment of phosphopeptides using a commercially available gallium(III)-IMAC column (PhosphoProfile, Sigma). Phosphopeptide enrichment using the reagents supplied with the column is incomplete and biased toward the recovery and/or detection of smaller, singly phosphorylated peptides. In contrast, elution with base (0.4 M ammonium hydroxide) gives efficient and balanced recovery of both singly and multiply phosphorylated peptides, while loading peptides in a strong acidic solution (1% trifluoracetic acid) further increases selectivity toward phosphopeptides, with minimal carryover of nonphosphorylated peptides. 2,5-Dihydroxybenzoic acid, a matrix commonly used when analyzing phosphopeptides by matrix-assisted laser desorption/ionization mass spectrometry was also evaluated as an additive in loading and eluting solvents. Elution with 50% acetonitrile containing 20 mg/mL dihydroxybenzoic acid and 1% phosphoric acid gave results similar to those obtained using ammonium hydroxide as the eluent, although the latter showed the highest specificity for phosphorylated peptides. PMID:19183793

  4. [Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography].

    PubMed

    Yu, Ruipeng; Hu, Zhongyang; Ye, Mingli; Che, Jinshui

    2012-04-01

    A method based on accelerated solvent extraction-ion chromatography (ASE-IC) was developed for the simultaneous determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in plastic samples. The accelerated solvent extraction was employed as the pretreatment method for the simultaneous extraction of the Cr(III) and Cr(VI) from the samples. Cr(III) and Cr(VI) were derivatized with 2,6-pyridinedicarboxylic acid (PDCA) and 1,5-diphenyl-carbazide (DPC), and detected by an ultraviolet-visible (UV-Vis) detector at UV and visible wavelengths, respectively. The results showed that the limits of detection for Cr(III) and Cr(VI) were 5.0 microg/L and 0.5 microg/L and the good linearities of the calibration curves for them were in the ranges of 50 - 1 000 microg/L (r2 = 0.9994) and 5.0 - 100 microg/L (r2 = 0.9998), respectively. The recoveries were between 90.7% and 101.1% with the relative standard deviations (RSDs) of 1.7% -4.4% for Cr(III) and Cr(VI). The method is sensitive, reproducible and adaptable to the simultaneous determination of Cr(III) and Cr(VI) in the plastic samples. PMID:22799201

  5. One-step purification of rabbit histidine rich glycoprotein by dye-ligand affinity chromatography with metal ion requirement.

    PubMed

    Mori, S; Nishibori, M; Yamaoka, K; Okamoto, M

    2000-11-15

    A simple method for purification of the histidine rich glycoprotein (rHRG) from rabbit sera was developed. The rHRG was purified by one-step affinity chromatography using the triphenylmethane dye "acid fuchsin" as a specific ligand, which gave an overall yield above 80%. Interestingly, the binding of rHRG to the ligand required the divalent transition-metal ions such as Zn2+, Ni2+, and Co2+ at pH 9.5. In the presence of 0.5 mM ZnCl2, the binding was enhanced 15 times compared with that in the absence of ZnCl2. Bound rHRG was efficiently eluted from the affinity absorbent with 100 mM imidazole or histidine. Purified rHRG was homogeneous with an Mr of 94 kDa when analyzed by SDS-PAGE, whereas isoelectric focusing revealed microheterogeniety with pI values ranging from 6.3 to 6.8. Blotting analysis with lectins specific for carbohydrate moieties and treatment with glycosidases demonstrated that rHRG is a highly N-glycosylated protein with diverse carbohydrate structures. PMID:11185553

  6. A new method for the determination of sulphide in gastrointestinal contents and whole blood by microdistillation and ion chromatography.

    PubMed

    Richardson, C J; Magee, E A; Cummings, J H

    2000-03-01

    Hydrogen sulphide is produced in the human large intestine by the bacterial reduction of dietary inorganic sulphate and sulphite and by fermentation of sulphur amino acids. Sulphide may damage the colonic epithelium and has been implicated in the pathogenesis of ulcerative colitis. The accurate measurement of sulphide in biological samples, particularly in gut contents is difficult due to the volatile nature of the compound, and the viscosity and turbidity of the samples. Here we describe a method for the determination of sulphide in gut contents and whole blood which overcomes these problems. Initially, samples are treated with zinc acetate to trap sulphide. A microdistillation pretreatment is then used, which releases sulphide from its stable, stored state, coupled to ion chromatography with electrochemical detection. The limit of detection of the method was determined as 2.5 micromol/l, which enabled sulphide levels in gut contents and whole blood samples obtained from humans to be accurately determined. A preliminary investigation in healthy human subjects showed blood sulphide ranged from 10 to 100 micromol/l. Whole blood sulphide did not change significantly when increasing amounts of protein from meat were fed. However, faecal sulphide did show a significant increase from 164 to 754 nmol/g in four subjects fed diets which contained 60 and 420 g meat. PMID:10699427

  7. Custom-tailored adsorbers: A molecular dynamics study on optimal design of ion exchange chromatography material.

    PubMed

    Lang, Katharina M H; Kittelmann, Jörg; Pilgram, Florian; Osberghaus, Anna; Hubbuch, Jürgen

    2015-09-25

    The performance of functionalized materials, e.g., ion exchange resins, depends on multiple resin characteristics, such as type of ligand, ligand density, the pore accessibility for a molecule, and backbone characteristics. Therefore, the screening and identification process for optimal resin characteristics for separation is very time and material consuming. Previous studies on the influence of resin characteristics have focused on an experimental approach and to a lesser extent on the mechanistic understanding of the adsorption mechanism. In this in silico study, a previously developed molecular dynamics (MD) tool is used, which simulates any given biomolecule on resins with varying ligand densities. We describe a set of simulations and experiments with four proteins and six resins varying in ligand density, and show that simulations and experiments correlate well in a wide range of ligand density. With this new approach simulations can be used as pre-experimental screening for optimal adsorber characteristics, reducing the actual number of screening experiments, which results in a faster and more knowledge-based development of custom-tailored adsorbers. PMID:26319376

  8. Elution profiles of lanthanides with α-hydroxyisobutyric acid by ion exchange chromatography using fine resin.

    PubMed

    Trikha, Rahul; Sharma, Bal Krishan; Sabharwal, Kanwal Nain; Prabhu, Krishan

    2015-11-01

    Experiments were carried out using a strong acid cation exchange resin with a particle size of 75-150 μm, termed as "fine resin" in hydrogen ion form for the elution of individual lanthanides Sm, Eu, Gd, Tb, and Dy that are produced as fission products in the spent nuclear fuel and generated in the effluent during reprocessing of spent nuclear fuel. Batch experiments were carried out to study the effect of concentration of nitric acid on distribution coefficient. The distribution coefficient values for these individual lanthanides were determined in nitric acid medium in the concentration range of 0.01-4.0 N. Uptake of each individual lanthanide by resin was increased with increased nitric acid concentration from 0.01 to 0.5 N and remained similar from 0.5 to 1.0 N and decreased thereafter up to 4.0 N. Column experiments were also carried out using the same resin to study the parameters like pH of the eluent, flow rate, and resin bed height under isocratic elution conditions for eluting lanthanide elements using α-hydroxyisobutyric acid as eluent. The results of this study have indicated the possibility for the elution of individual lanthanides. PMID:26333182

  9. Monitoring fermentation media by ion-chromatography with a double chamber bulk acoustic wave detector.

    PubMed

    Xie, Y T; Zeng, H S; Yao, S Z; Wei, W Z

    1999-12-01

    A reliable ion-chromatographic (IC) method with a novel double chamber bulk acoustic wave (DCBAW) detector was developed for monitoring five important inorganic cations (Na(+), K(+), NH(4)(+), Ca(2+), Mg(2+)) in biological culture media. A Shimpack IC-C1 analytical column with 5 mM hydrochloric acid and 2 mM acetonitrile as mobile phase was used. All investigated inorganic cations could be detected and qualified in the range of 0.1-100 mg/l. Results showed that the consumption velocities of Mg(2+) and K(+) are related to the growth of the cells and decrease fastest during the first 2-5 h. Mg became a growth limiting factor at concentration below 0.1 mg/l. The concentrations of the other cations stayed nearly constant during the whole fermentation process. The simple sample preparation, short analytical time and accurate results made it a useful tool for the on-line monitoring, controlling and optimization of the fermentation process. PMID:18967796

  10. Separation of oxyanions of sulphur by single-column ion-chromatography.

    PubMed

    Beveridge, A; Pickering, W F; Slavek, J

    1988-04-01

    After stabilization of sulphite by addition of a five-fold excess of formaldehyde, mixtures of sulphite, sulphate and thiosulphate are readily separated by HPLC. For use with Vydac columns (302IC or 300IC) a suitable eluent is 1-3mM phthalic acid (pH 5-6), and the eluted ions may be detected by means of the change in refractive index or the absorbance at 290 nm. With a flow-rate of 2 ml/min, anion elution times are about 2.7 (0.7) min for HOCH(2)SO(-)(3), 7.5 (2.6) min for SO(2-)(4) and 8.4 (5.2) min for S(2)O(2-)(3), the values in parentheses being those for the shorter 300IC column. Detection limits for sulphite and sulphate were around 1 mg/l., with relative standard deviations of 2-3% at higher levels. The sensitivity for S(2)O(2-)(3) was an order of magnitude lower. The proposed method has advantages over earlier procedures based on alkaline eluents. PMID:18964518

  11. Simultaneous determination of Ephedra sinica and Citrus aurantium var. amara alkaloids by ion-pair chromatography.

    PubMed

    Ganzera, M; Lanser, C; Stuppner, H

    2005-05-15

    Ephedra sinica (Ma Huang) preparations have recently gained a lot of attention because of serious side effects associated with their prolonged consumption. Citrus aurantium var. amara is now used as an alternative, despite the fact that similar side effects are suspected. We have developed and validated the first analytical procedure for the simultaneous determination of all major alkaloids from both species. Using the ion-pairing reagent SDS, a C-18 stationary phase (3mum material) and a pH-gradient for elution enabled the baseline separation of six alkaloids ((+/-)-octopamine, (+/-)-synephrine, tyramine, (-)-norephedrine, (+)-pseudoephedrine and (-)-ephedrine) within less than 30min. The method is sensitive (LOD

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  14. The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

    SciTech Connect

    Johnson, S.

    1999-02-12

    The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

  15. Liquid chromatography-tandem mass spectrometric ion-switching determination of chlorantraniliprole and flubendiamide in fruits and vegetables.

    PubMed

    Caboni, Pierluigi; Sarais, Giorgia; Angioni, Alberto; Vargiu, Simona; Pagnozzi, Daniela; Cabras, Paolo; Casida, John E

    2008-09-10

    The anthranilic and phthalic diamides, chlorantraniliprole (CAP) and flubendiamide (FLU), respectively, represent a new class of very effective insecticides that activate the ryanodine-sensitive intracellular calcium release channel (ryanodine receptor). This paper reports an analytical method for the simultaneous determination of the two insecticides on fruits and vegetables by liquid chromatography-electrospray tandem mass spectrometry operated in the positive and negative ionization switching mode. The two diamides were extracted with acetonitrile and separated on a Zorbax Column Eclipse XDB C8 (4.6 mm x 150 mm i.d., 3 microm) by isocratic elution with a mobile phase consisting of acetonitrile and water with 0.1% formic acid pumped at a flow rate of 0.4 mL/min. The diamides were selectively detected by multiple reaction monitoring for transitions of proton adduct precursor ions simultaneously: positive m/z 484.3-->285 for CAP, m/z 445.5-->169 for internal standard, and negative m/z 681.4-->253 for FLU. For CAP calibration in the positive mode was linear over a working range of 2 to 1000 microg/L with r > 0.992. The limit of detection (LOD) and limit of quantification (LOQ) for CAP were 0.8 and 1.6 microg/kg, respectively. For FLU in the negative mode the corresponding values were 1-1000 microg/L for linear working range, with r > 0.996 and 0.4 and 0.8 microg/L for LOD and LOQ, respectively. Moreover, the presence of interfering compounds in the fruit and vegetable extracts was found to be minimal. Due to the linear behavior of the MS detector response for the two analytes, it was concluded that the multiple reaction transitions of molecular ions in the ion-switching mode can be used for analytical purposes, that is, for identification and quantification of diamides in fruit and vegetable extracts at trace levels. PMID:18690687

  16. Choline in infant formula and adult nutritionals by ion chromatography and suppressed conductivity: First Action 2012.20.

    PubMed

    Oates, Kassandra; Chen, Lillian; De Borba, Brian; Mohindra, Deepali; Rohrer, Jeffrey; Dowell, Dawn

    2013-01-01

    Single-laboratory validation (SLV) data from a method for the determination of choline in infant formula and adult nutritionals by ion chromatography (IC) and suppressed conductivity were generated and presented to the Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Expert Review Panel (ERP) at the AOAC Annual Meeting held in Las Vegas, NV, during September 30 to October 3, 2012. The ERP reviewed the data and concluded that the data met the standard method performance requirements (SMPRs) established and approved the method as AOAC Official First Action. At the ERP's request, a second, full SLV was performed on 17 SPIFAN matrixes that included fortified and placebo products. Prior to IC analysis, microwave-assisted acid hydrolysis was used to digest and release bound choline from powder and ready-to-feed (RTF) infant formula and adult nutritional samples. Following hydrolysis, separation of choline from common cations was achieved on a Thermo Scientific Dionex IonPac CS19 column followed by suppressed conductivity detection. Total choline was measured and reported as the choline ion in mg/100 g reconstituted material or RTF as-is. The system was calibrated over the analytical range specified in the SMPR (2-250 mg/100 g). Recoveries of spiked samples at 50 and 100% of the fortified choline amounts ranged from 93.1 to 100.7% with RSDs < or = 6.7% for product containing < 2 mg/100 g and < or = 4.1% for product containing 2-100 mg/100 g. Accuracy for the National Institute of Standards and Technology Standard Reference Material 1849a was determined over a 6-day interval and found to be 10.2 +/- 0.2 mg/100 g calculated as the reconstituted powder with an RSD of 1.8%. The LOD was determined to be 0.009, and the LOQ 0.012 mg/100 g, well below the SMPR requirements of 0.7 and 2 mg/100 g, respectively. Repeatability RSDs over the range of the assay (2-200 mg/100 g) ranged from 1.0 to 5.93% PMID:24645521

  17. Ion exchange chromatography of proteins-predictions of elution curves and operating conditions. II. Experimental verification.

    PubMed

    Yamamoto, S; Nakanishi, K; Matsuno, R; Kamijubo, T

    1983-05-01

    The applicability and validity of the model developed in Part I were confirmed experimentally. In this article, various proteins were eluted both by stepwise and linear gradient elution on DEAE ion exchangers under a variety of experimental conditions. Adsorption isotherms were measured as a function of ionic strength in batch experiments. The moment method was employed for the determination of various parameters such as the gel-phase diffusion coefficient and the longitudinal dispersion coefficient. By use of these parameters and the experimentally measured ionic strength of the peak position, the number of plates was determined according to the method described in Part I. Theoretical elution curves were calculated with the experimentally measured adsorption equilibria and the number of plates. Good agreement was observed between theory an experiments. Various factors affecting the separation were investigated. It was found that the effect of the number of plates for salts, N'(p), was negligible except the case of stepwise elution of high ionic strength buffer. When elution curves were symmetrical, the widths of the elution curves were inversely proportional to the square root of the number of plates of proteins, N(p), as in other chromatographic techniques. A simple graphical method for prediction of the peak position in linear gradient elution described in Part I was found applicable when the elution curves were symmetrical. A useful correlation of prediction of the peak width in a linear gradient elution was proposed on the basis of the approximate solution derived in Part I of this study. This graphical method and correlation permit easy prediction of the peak position and peak width in linear gradient elution in the case of symmetrical elution curves. PMID:18548766

  18. [Determination of heat stable salt anions in alkanolamine desulphurization solution by ion chromatography].

    PubMed

    Tang, Fei; Wang, Yujie; Luo, Qin; Tang, Meng; Chen, Gengliang

    2012-04-01

    To control the potential risk of natural gas purification plants, an ion chromatographic method has been developed to determine the heat stable salts (HSS) in alkanolamine desulphurization solution. Seven HSS anions, including CH3COO(-), HCOO(-), Cl(-), SO4(2-), C2O4(2-), S2O3(2-), SCN(-), were determined in a single injection. Before the chromatographic analysis, these industrial samples were pretreated by three steps, i.e. filtration, solid phase extraction and dilution. Using the gradient elution with KOH solution, all of the seven anions have been separated and determined by a conductivity detector. As the calibration results, the linear range of this method was 0.01 - 0.5 mmol/L for the 7 anions. The limit of detection (LOD, S/N = 3) was 0. 1 mg/L for each anion. By spiked standard solutions in the samples, the recoveries were in the range of 80.0% - 100.3%. The repeatability of this method was evaluated at five different concentrations. The relative standard deviations (RSD, n = 10) of the peak areas were in the range of 0.94% to 3.99%. Moreover, the reproducibility of the method was also tested in three different laboratories and it was acceptable with the RSD <5%. The proposed method has been applied to the determination of HSS in eight gas purification plants, three oil refineries and one coal gas plant and to monitor a gas purification plant continuously in 15 days. It's shown that the accuracy and precision of this method are satisfactory. PMID:22799195

  19. Comparison of Gas Chromatography-Mass Spectrometry and Gas Chromatography-Tandem Mass Spectrometry with Electron Ionization and Negative-Ion Chemical Ionization for Analyses of Pesticides at Trace Levels in Atmospheric Samples

    PubMed Central

    Raina, Renata; Hall, Patricia

    2008-01-01

    A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) with gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode with both electron ionization (EI) and negative-ion chemical ionization (NCI) are presented for over 50 pesticides ranging from organochlorines (OCs), organophosphorus pesticides (OPs) and pre-emergent herbicides used in the Canadian prairies (triallate, trifluralin, ethalfluralin). The developed GC-EI/SIM, GC-NCI/SIM, and GC-NCI/SRM are suitable for the determination of pesticides in air sample extracts at concentrations <100 pg μL−1 (<100 pg m−3 in air). No one method could be used to analyze the range of pre-emergent herbicides, OPs, and OCs investigated. In general GC-NCI/SIM provided the lowest method detection limits (MDLs commonly 2.5–10 pg μL−1) along with best confirmation (<25% RSD of ion ratio), while GC-NCI/SRM is recommended for use where added selectivity or confirmation is required (such as parathion-ethyl, tokuthion, carbofenothion). GC-EI/SRM at concentration <100 pg μL−1 was not suitable for most pesticides. GC-EI/SIM was more prone to interference issues than NCI methods, but gave good sensitivity (MDLs 1–10 pg μL−1) for pesticides with poor NCI response (OPs: sulfotep, phorate, aspon, ethion, and OCs: alachlor, aldrin, perthane, and DDE, DDD, DDT). PMID:19609395

  20. Analysis of anions in aqueous samples by ion chromatography and capillary electrophoresis. A comparative study of peak modeling and validation criteria.

    PubMed

    Tamisier-Karolak, S L; Le Potier, I; Barlet, O; Czok, M

    1999-08-13

    The object of this study is the comparison of two methods for the quantitative analysis of anions in aqueous samples: ion chromatography with conductimetric detection, and capillary zone electrophoresis with indirect photometric detection. The comparison includes modeling of experimental peaks as well as statistical validation criteria according to the recommendations of the International Conference on Harmonisation. In ion chromatography, peak shapes are Gaussian or exponentially modified Gaussian, and the number of theoretical plates calculated using the appropriate mathematical relations correspond well to those obtained from statistical moments. Peaks in capillary electrophoresis, however, do not follow the same models. A different model, treating the peaks as right angle triangles, has been studied. Equations corresponding to this model permit a good estimation of plate numbers. The statistical validation of these methods includes detection limits, linearity, accuracy and precision. Overall, ion chromatography yields better validation results than capillary electrophoresis. In the latter method the injection mode plays an important role, with voltage injection giving lower detection limits than hydrodynamic injection. PMID:10481986

  1. Ultrafiltration by a compacted clay membrane-II. Sodium ion exclusion at various ionic strengths

    USGS Publications Warehouse

    Hanshaw, B.B.; Coplen, T.B.

    1973-01-01

    Several recent laboratory studies and field investigations have indicated that shales and compacted clay minerals behave as semipermeable membranes. One of the properties of semipermeable membranes is to retard or prevent the passage of charged ionic species through the membrane pores while allowing relatively free movement of uncharged species. This phenomenon is termed salt filtering, reverse osmosis, or ultrafiltration. This paper shows how one can proceed from the ion exchange capacity of clay minerals and, by means of Donnan membrane equilibrium concept and the Teorell-Meyer-Siever theory, develop a theory to explain why and to what extent ultrafiltration occurs when solutions of known concentration are forced to flow through a clay membrane. Reasonable agreement between theory and laboratory results were found. The concentration of the ultrafiltrate was always greater than predicted because of uncertainty in values of some parameters in the equations. Ultrafiltration phenomena may be responsible for the formation of some subsurface brines and mineral deposits. The effect should also be taken into consideration in any proposal for subsurface waste emplacement in an environment containing large quantities of clay minerals. ?? 1973.

  2. Influence of Equilibration Time in Solution on the Inclusion/Exclusion Topology Ratio of Host-Guest Complexes Probed by Ion Mobility and Collision-Induced Dissociation.

    PubMed

    Carroy, Glenn; Daxhelet, Charlotte; Lemaur, Vincent; De Winter, Julien; De Pauw, Edwin; Cornil, Jérôme; Gerbaux, Pascal

    2016-03-18

    Host-guest complexes are formed by the creation of multiple noncovalent bonds between a large molecule (the host) and smaller molecule(s) or ion(s) (the guest(s)). Ion-mobility separation coupled with mass spectrometry nowadays represents an ideal tool to assess whether the host-guest complexes, when transferred to the gas phase upon electrospray ionization, possess an exclusion or inclusion nature. Nevertheless, the influence of the solution conditions on the nature of the observed gas-phase ions is often not considered. In the specific case of inclusion complexes, kinetic considerations must be taken into account beside thermodynamics; the guest ingression within the host cavity can be characterized by slow kinetics, which makes the complexation reaction kinetically driven on the timescale of the experiment. This is particularly the case for the cucurbituril family of macrocyclic host molecules. Herein, we selected para-phenylenediamine and cucurbit[6]uril as a model system to demonstrate, by means of ion mobility and collision-induced dissociation measurements, that the inclusion/exclusion topology ratio varies as a function of the equilibration time in solution prior to the electrospray process. PMID:26880721

  3. Quality evaluation of extracted ion chromatograms and chromatographic peaks in liquid chromatography/mass spectrometry-based metabolomics data

    PubMed Central

    2014-01-01

    Background Extracted ion chromatogram (EIC) extraction and chromatographic peak detection are two important processing procedures in liquid chromatography/mass spectrometry (LC/MS)-based metabolomics data analysis. Most commonly, the LC/MS technique employs electrospray ionization as the ionization method. The EICs from LC/MS data are often noisy and contain high background signals. Furthermore, the chromatographic peak quality varies with respect to its location in the chromatogram and most peaks have zigzag shapes. Therefore, there is a critical need to develop effective metrics for quality evaluation of EICs and chromatographic peaks in LC/MS based metabolomics data analysis. Results We investigated a comprehensive set of potential quality evaluation metrics for extracted EICs and detected chromatographic peaks. Specifically, for EIC quality evaluation, we analyzed the mass chromatographic quality index (MCQ index) and propose a novel quality evaluation metric, the EIC-related global zigzag index, which is based on an EIC's first order derivatives. For chromatographic peak quality evaluation, we analyzed and compared six metrics: sharpness, Gaussian similarity, signal-to-noise ratio, peak significance level, triangle peak area similarity ratio and the local peak-related local zigzag index. Conclusions Although the MCQ index is suited for selecting and aligning analyte components, it cannot fairly evaluate EICs with high background signals or those containing only a single peak. Our proposed EIC related global zigzag index is robust enough to evaluate EIC qualities in both scenarios. Of the six peak quality evaluation metrics, the sharpness, peak significance level, and zigzag index outperform the others due to the zigzag nature of LC/MS chromatographic peaks. Furthermore, using several peak quality metrics in combination is more efficient than individual metrics in peak quality evaluation. PMID:25350128

  4. Analysis of 19-nortestosterone residue in animal tissues by ion-trap gas chromatography-tandem mass spectrometry*

    PubMed Central

    Jiang, Jin-qing; Zhang, Lei; Li, Guang-ling; Zhang, Hai-tang; Yang, Xue-feng; Liu, Jun-wei; Li, Ren-feng; Wang, Zi-liang; Wang, Jian-hua

    2011-01-01

    A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with β-glucuronidase from Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol/L). Next, the homogenate was mixed with methanol and heated at 60 °C for 15 min, then placed in an ice-bath at −18 °C for 2 h. After liquid-liquid extraction with n-hexane, the analytes were subjected to a normal-phase solid phase extraction (SPE) C18 cartridge for clean-up. The dried organic extracts were derivatized with heptafluorobutyric anhydride (HFBA), and then the products were injected into GC-MS. Using electron impact mass spectrometry (EI-MS) with positive chemical ionization (PCI), four diagnostic ions (m/z 666, 453, 318, and 306) were determined. A standard calibration curve over the concentration range of 1–20 ng/g was reached, with Y=467 084X−68 354 (R 2=0.999 7) for 19-NT, and the detection limit was 0.3 ng. When applied to spiked samples collected from bovine and ovine, the recoveries ranged from 63% to 101% with relative standard deviation (RSD) between 2.7% and 8.9%. The procedure is a highly efficient, sensitive, and more economical method which offers considerable potential to resolve cases of suspected nandrolone doping in husbandry animals. PMID:21634039

  5. Study of the in vitro metabolism of TJ0711 using ultra high performance liquid chromatography with quadrupole time-of-flight and ultra fast liquid chromatography with quadrupole linear ion trap mass spectrometry.

    PubMed

    Hu, Lei; Lv, Zhenhua; Li, Gao; Xu, Xiaolong; Zhang, Chenghao; Cao, Peng; Huang, Jiangeng; Si, Luqin

    2015-06-01

    TJ0711 (1-[4-(2-methoxyethyl)phenoxy]-3-[2-(2-methoxyphenoxy)ethylamino]-2-propanol) is a novel β-adrenoreceptor blocker with vasodilating activity. The aim of this study was to investigate the in vitro metabolic properties of TJ0711 from both qualitative and quantitative aspects using mouse, rat, dog, and human liver microsomes as well as rat hepatocytes. Two modern liquid chromatography with tandem mass spectrometry systems, ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry and ultra fast liquid chromatography with quadrupole linear ion trap mass spectrometry, were utilized for the analysis. To better characterize the metabolic pathways of TJ0711, two major metabolites were incubated under the same conditions as that for TJ0711. TJ0711 was extensively metabolized in vitro, and a total of 34 metabolites, including 19 phase I and 15 phase II metabolites, were identified. Similar metabolite profiles were observed among species, and demethylation, hydroxylation, carboxylic acid formation, and glucuronidation were proposed as the major metabolic routes. Significant interspecies differences were observed in the metabolic stability studies of TJ0711. Furthermore, gender differences were significant in mice, rats, and dogs, but were negligible in humans. The valuable information provided in this work will be useful in planning and interpreting further pharmacokinetic, in vivo metabolism and toxicological studies of this novel β-blocker. PMID:25800512

  6. Fast filtration sampling protocol for mammalian suspension cells tailored for phosphometabolome profiling by capillary ion chromatography - tandem mass spectrometry.

    PubMed

    Kvitvang, Hans F N; Bruheim, Per

    2015-08-15

    Capillary ion chromatography (capIC) is the premium separation technology for low molecular phosphometabolites and nucleotides in biological extracts. Removal of excessive amounts of salt during sample preparation stages is a prerequisite to enable high quality capIC separation in combination with reproducible and sensitive MS detection. Existing sampling protocols for mammalian cells used for GC-MS and LC-MS metabolic profiling can therefore not be directly applied to capIC separations. Here, the development of a fast filtration sampling protocol for mammalian suspension cells tailored for quantitative profiling of the phosphometabolome on capIC-MS/MS is presented. The whole procedure from sampling the culture to transfer of filter to quenching and extraction solution takes less than 10s. To prevent leakage it is critical that a low vacuum pressure is applied, and satisfactorily reproducibility was only obtained by usage of a vacuum pressure controlling device. A vacuum of 60mbar was optimal for filtration of multiple myeloma Jjn-3 cell cultures through 5μm polyvinylidene (PVDF) filters. A quick deionized water (DI-water) rinse step prior to extraction was tested, and significantly higher metabolite yields were obtained during capIC-MS/MS analyses in this extract compared to extracts prepared by saline and reduced saline (25%) washing steps only. In addition, chromatographic performance was dramatically improved. Thus, it was verified that a quick DI-water rinse is tolerated by the cells and can be included as the final stage during filtration. Over 30 metabolites were quantitated in JJN-3 cell extracts by using the optimized sampling protocol with subsequent capIC-MS/MS analysis, and up to 2 million cells can be used in a single filtration step for the chosen filter and vacuum pressure. The technical set-up is also highly advantageous for microbial metabolome filtration protocols after optimization of vacuum pressure and washing solutions, and the reduced salt content of the extract will also improve the quality of LC-MS analysis due to lower salt adduct ion formation. PMID:26151192

  7. Identification of chlorinated fatty acids in fish by gas chromatography/mass spectrometry with negative ion chemical ionization of pentafluorobenzyl esters.

    PubMed

    Zhuang, Wenshan; McKague, A Bruce; Reeve, Douglas W; Carey, John H

    2004-01-01

    This paper reports the development of a technique for identifying and confirming chlorinated fatty acids previously detected in fish by gas chromatography (GC) with halogen-specific detection (XSD). Fatty acid methyl esters (FAMEs) including chlorinated FAMEs within fractions of reversed-phase high-performance liquid chromatography of transesterified fish extracts were derivatized to pentafluorobenzyl esters, which were subjected to GC/mass spectrometry (MS) with negative ion chemical ionization (NICI). Pentafluorobenzyl esters displayed reasonably good GC characteristics, a very high ionization efficiency and a low degree of fragmentation. Chloride ion chromatograms extracted at m/z 35 and 37 from full scans were utilized for locating traces of chlorinated unknowns in the GC elution profile so that their mass spectra could be readily displayed. Significant ions displayed in the mass spectrum scanned in a narrow range of retention time where a chlorinated unknown was located were evaluated using ion chromatograms extracted at the m/z of these ions. The chromatographic peaks of those ions derived from the analyte were expected to center at that specific retention time, whereas those originating from matrix compounds were not. The isotopic patterns of chlorinated ions were also examined against their theoretical relative abundances. Using this approach, three metabolism-related dichloro fatty acids previously identified by GC/XSD in filet extracts of white sucker sampled downstream from a bleached kraft pulp mill were confirmed: dichlorooctadecanoic, dichlorohexadecanoic and dichlorotetradecanoic acids. In addition, an isomer of dichlorotetradecanoic acid was found in a reference fish sample. As sample preparation is critical in this application, improved conditions for hydrolysis and pentafluorobenzyl esterification are also discussed. PMID:14760613

  8. Two-dimensional ion chromatography for the separation of ionic organophosphates generated in thermally decomposed lithium hexafluorophosphate-based lithium ion battery electrolytes.

    PubMed

    Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Menzel, Jennifer; Wiemers-Meyer, Simon; Winter, Martin; Nowak, Sascha

    2015-08-28

    A two-dimensional ion chromatography (IC/IC) technique with heart-cutting mode for the separation of ionic organophosphates was developed. These analytes are generated during thermal degradation of three different commercially available Selectilyte™ lithium ion battery electrolytes. The composition of the investigated electrolytes is based on 1M lithium hexafluorophosphate (LiPF6) dissolved in ethylene carbonate/dimethyl carbonate (50:50wt%, LP30), ethylene carbonate/diethyl carbonate (50:50wt%, LP40) and ethylene carbonate/ethyl methyl carbonate (50:50wt%, LP50). The organophosphates were pre-separated from PF6(-) anion on the low capacity A Supp 4 column, which was eluted with a gradient step containing acetonitrile. The fraction containing analytes was retarded on a pre-concentration column and after that transferred to the high capacity columns, where the separation was performed isocratically. Different stationary phases and eluents were applied on the 2nd dimension for the investigation of retention times, whereas the highly promising results were obtained with a high capacitive A Supp 10 column. The organophosphates generated in LP30 and LP40 electrolytes could be separated by application of an aqueous NaOH eluent providing fast analysis time within 35min. For the separation of the organophosphates of LP50 electrolyte due to its complexity a NaOH eluent containing a mixture of methanol/H2O was necessary. In addition, the developed two dimensional IC method was hyphenated to an inductively coupled plasma mass spectrometer (ICP-MS) using aqueous NaOH without organic modifiers. This proof of principle measurement was carried out for future quantitative investigation regarding the concentration of the ionic organophosphates. Furthermore, the chemical stability of several ionic organophosphates in water and acetonitrile at room temperature over a period of 10h was investigated. In both solvents no decomposition of the investigated analytes was observed and therefore water as solvent for dilution of samples was proved as suitable. PMID:26209196

  9. Wide-scope screening and quantification of 50 pesticides in wine by liquid chromatography/quadrupole time-of-flight mass spectrometry combined with liquid chromatography/quadrupole linear ion trap mass spectrometry.

    PubMed

    He, Zeying; Xu, Yaping; Wang, Lu; Peng, Yi; Luo, Ming; Cheng, Haiyan; Liu, Xiaowei

    2016-04-01

    In this paper, a wide scope screening method of pesticides in wine was established using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF MS) and liquid chromatography/quadrupole linear ion trap mass spectrometry (LC-QqLIT MS). Information dependent acquisition (IDA) experiments are used to obtain both MS and MS/MS information for LC-QTOF MS analysis. For LC-QqLIT MS analysis, MS/MS spectra of target pesticides were simultaneously acquired using Enhanced Product Ion (EPI) mode at very low concentrations to increase the confidence in analytical results of multiple reaction monitoring (MRM) by library searching. Method validation was carried out using 50 pesticides commonly used in vineyards. The LOQs, linearity, repeatability were determined and good enough for quantification. The screening and quantification results obtained using LC-QTOF MS and LC-QqLIT MS were compared. Contaminants were screened against libraries containing over 2800 compounds based on accurate mass, isotopic patterns, and MS/MS spectra searching to extend the scope of this methodology to non-target screening. PMID:26593613

  10. Ion-exclusion chromatographic separations of C1-C6 aliphatic carboxylic acids on a sulfonated styrene-divinylbenzene co-polymer resin column with 5-methylhexanoic acid as eluent.

    PubMed

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

    2003-05-16

    The application of C7 aliphatic carboxylic acids (heptanoic, 2-methylhexanoic, 5-methylhexanoic and 2,2-dimethyl-n-valeric acids) as eluents in ion-exclusion chromatography with conductimetric detection for C1-C6 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic and caproic acids) was carried out using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as a stationary phase. When using 0.05 mM sulfuric acid at pH 4.0 as the eluent, peak shapes of hydrophobic carboxylic acids (isovaleric, valeric, isocaproic and caproic acids) were tailed strongly. In contrast, when using 1 mM these C7 carboxylic acids at pH ca. 4 as the eluents, although system peaks (vacant peaks) corresponding to these C7 carboxylic acids appeared, peak shapes of these hydrophobic acids were improved drastically. Excellent simultaneous separation and relatively high sensitive conductimetric detection for these C1-C6 aliphatic carboxylic acids were achieved in 25 min on the TSKgel SCX column (150 x 6 mm I.D.) using 1 mM 5-methylhexanoic acid at pH 4.0 as the eluent. PMID:12830882

  11. Simultaneous detection and quantitation of highly water-soluble herbicides in serum using ion-pair liquid chromatography-tandem mass spectrometry.

    PubMed

    Wang, Kuang-Chuan; Chen, Shih-Ming; Hsu, Jung-Fa; Cheng, Sheaw-Guey; Lee, Ching-Kuo

    2008-12-15

    We report the simultaneous screening of highly polar, water-soluble, and less-volatile herbicides, including glyphosate, glufosinate, paraquat, and diquat, in serum using liquid chromatography-mass spectrometry. The herbicides were separated by solid-phase extraction using a Strata-XC cartridge. A heptafluorobutyric acid solution was chosen as the mobile phase for ion-pair liquid chromatography. Mass spectrometry was used for analysis and was optimized for operation in the positive mode for all analytes. The serum specimens were screened for the presence of the herbicides at the following concentrations: 5 ng/mL for glyphosate, 2 ng/mL for glufosinate, 1 ng/mL for diquat, and 5 ng/mL for paraquat. This is the first report on the simultaneous detection of these compounds. PMID:19022710

  12. The determination of underivatized chlorophenols in human urine by combined high performance liquid chromatography mass spectrometry and selected ion monitoring.

    PubMed

    Wright, L H; Edgerton, T R; Arbes, S J; Lores, E M

    1981-10-01

    A method for the determination of underivatized chlorophenols in human urine samples by combined high performance liquid chromatography mass spectrometry is described. Results obtained on individual samples are reported and compared with data obtained by alternative chromatographic methods. PMID:7295873

  13. Size exclusion chromatography to gain insight into the complex formation of carrot pectin methylesterase and its inhibitor from kiwi fruit as influenced by thermal and high-pressure processing.

    PubMed

    Jolie, Ruben P; Duvetter, Thomas; Verlinde, Philippe H C J; Van Buggenhout, Sandy; Van Loey, Ann M; Hendrickx, Marc E

    2009-12-01

    A size exclusion chromatography (HPSEC) method was implemented to study complex formation between carrot pectin methylesterase (PME) and its inhibitor (PMEI) from kiwi fruit in the context of traditional thermal and novel high-pressure processing. Evidence was gained that both thermal and high-pressure treatments of PME give rise to two distinct enzyme subpopulations: a catalytically active population, eluting from the size exclusion column, and an inactive population, aggregated and excluded from the column. When mixing a partly denatured PME sample with a fixed amount of PMEI, a PME-PMEI complex peak was observed on HPSEC, of which the peak area was highly correlated with the residual enzyme activity of the corresponding PME sample. This observation indicates complex formation to be restricted to the active PME fraction. When an equimolar mixture of PME and PMEI was subjected to either a thermal or a high-pressure treatment, marked differences were observed. At elevated temperature, enzyme and inhibitor remained united and aggregated as a whole, thus gradually disappearing from the elution profile. Conversely, elevated pressure caused the dissociation of the PME-PMEI complexes, followed by a separate action of pressure on enzyme and inhibitor. Remarkably, PMEI appeared to be pressure-resistant when compressed at acidic pH (ca. 4). PMID:19908835

  14. Total zinc quantification by inductively coupled plasma-mass spectrometry and its speciation by size exclusion chromatography-inductively coupled plasma-mass spectrometry in human milk and commercial formulas: Importance in infant nutrition.

    PubMed

    Fernández-Menéndez, Sonia; Fernández-Sánchez, María L; Fernández-Colomer, Belén; de la Flor St Remy, Rafael R; Cotallo, Gil Daniel Coto; Freire, Aline Soares; Braz, Bernardo Ferreira; Santelli, Ricardo Erthal; Sanz-Medel, Alfredo

    2016-01-01

    This paper summarises results of zinc content and its speciation in human milk from mothers of preterm and full-term infants at different stages of lactation and from synthetic formula milks. Human milk samples (colostrum, 7th, 14th, and 28th day after delivery) from Spanish and Brazilian mothers of preterm and full-term infants (and also formula milks) were collected. After adequate treatment of the sample, total Zn was determined, while speciation analysis of the Zn was accomplished by size exclusion chromatography coupled online with the ICP-MS. It is observed that total zinc content in human milk decreases continuously during the first month of lactation, both for preterm and full term gestations. All infant formulas analysed for total Zn were within the currently legislated levels. For Zn speciation analysis, there were no differences between preterm and full term human milk samples. Moreover Zn species elute mainly associated with immunoglobulins and citrate in human milk whey. Interestingly the speciation in formula milk whey turned out to be completely different as the observed Zn(2+) was bound almost exclusively to low molecular weight ligands (citrate) and only comparatively very low amounts of the metal appeared to be associated with higher mass biomolecules (e.g. proteins). PMID:26381570

  15. Field detection of bacillus spore aerosols with stand-alone pyrolysis-gas chromatography and ion mobility spectrometry

    NASA Astrophysics Data System (ADS)

    Snyder, A.; Maswadeh, Waleed M.; Parsons, John A.; Tripathi, Ashish; Meuzelaar, Henk L. C.; Dworzanski, Jacek P.; Kim, Man-Goo

    1999-12-01

    A commercially available, hand-held chemical vapor detector was modified to detect Gram-positive Bacillus subtilis var. globigii spores (BG) in outdoor field scenarios. An Airborne Vapor Monitor (AVM) ion mobility spectrometry (IMS) vapor detector was interfaced to a biological sample processing and transfer introduction system. The biological sample processing was accomplished by quartz tube pyrolysis (Py), and the resultant vapor was transferred by gas chromatography (GC) to the IMS detector. The Py-GC/IMS system can be described as a hyphenated device where two analytical dimensions, in series, allow the separation and isolation of individual components from the pyrolytic decomposition of biological analytes. Gram positive spores such as BG contain 5 - 15% by weight of dipicolinic acid (DPA), and picolinic acid is a pyrolysis product of DPA. Picolinic acid has a high proton affinity, and it is detected in a sensitive fashion by the atmospheric pressure-based IMS device. Picolinic acid occupies a unique region in the GC/IMS data domain with respect to other bacterial pyrolysis products. A 1000 to 1, air-to-air, aerosol concentrator was interfaced to the Py-GC/IMS instrument, and the system was placed in an open-air, Western United States desert environment. The system was tested with BG spore aerosol releases, and the instrument was remotely operated during a trial. A Met-One aerosol particle counter was placed next to the Py-GC/IMS so as to obtain a real-time record of the ambient and bacterial aerosol challenges. The presence/absence of an aerosol event, determined by an aerosol particle counter and a slit sampler-agar plate system, was compared to the presence/absence of a picolinic acid response in a GC/IMS data window at selected times in a trial with respect to a BG challenge. In the 21 BG trials, the Py-GC/IMS instrument experienced two true negatives, no false positives, and the instrument developed a software failure in one trial. The remaining 18 trials were true positive determinations for the presence of BG aerosol, and a limit of detection for the Py-GC/IMS instrument was estimated at approximately 3300 BG spore-containing particles.

  16. Effect of suppressor current intensity on the determination of glyphosate and aminomethylphosphonic acid by suppressed conductivity ion chromatography.

    PubMed

    Dimitrakopoulos, Ioannis K; Thomaidis, Nikolaos S; Megoulas, Nikolaos C; Koupparis, Michael A

    2010-05-28

    This paper presents the application of ion chromatography with electrolytic eluent generation and mobile phase suppression for the direct conductimetric detection of glyphosate and its degradation product aminomethylphosphonic acid (AMPA). The compounds were separated on a Dionex AS18 anion exchange column with a 12-40 mM KOH step gradient from 9 to 9.5 min. The effect of the suppressor current intensity on the electrostatic interaction of these amphoteric compounds with the suppressor cation exchange membranes was evaluated. A suppressor current gradient technique was proposed for the limitation of peak broadening and baseline noise, in order to improve method sensitivity and detectability. It was observed that residual sample carbonates co-eluted with AMPA when a large injection loop was installed for the low level determination of both compounds in natural waters. For this reason, glyphosate was isocratically eluted using 33 mM KOH in order to decrease analysis time within 10 min and a column clean up step using 100 mM KOH was used to ensure retention time reproducibility. The developed method was applied to the analysis of drinking and natural water and it was further successfully applied to orange samples with slight modifications. Instrumental LOD for glyphosate was 0.24 microg/L, while method LOD was 0.54 microg/L for spring waters and 0.01 mg/kg for oranges using a 1000 microL direct loop injection of the sample. Intra-day and inter-day precision (as %RSD) for water samples was 4.6% and 12% at a spiking level of 2 microg/L, and the recovery ranged from 64% to 88% depending on sample conductivity. For orange samples, the inter-day precision was 1.4% at a spiking level of 4.4 mg/kg, while overall recovery was 103%. The developed method is direct, fast, sensitive and relatively inexpensive, and could be used as an ideal fast screening tool for the monitoring of glyphosate residues in water and fruit samples. PMID:20399436

  17. Field detection and identification of a bioaerosol suite by pyrolysis-gas chromatography-ion mobility spectrometry

    NASA Astrophysics Data System (ADS)

    Snyder, A. Peter; Tripathi, Ashish; Maswadeh, Waleed M.; Ho, Jim; Spence, Mel

    2002-06-01

    Improvements were made to a pyrolysis-gas chromatography-ion mobility spectrometry stand-alone biodetector to provide more pyrolyzate compound information to the IMS detector module. Air carrier gas flowing continuously through the pyrolysis tube, the rate of air flow, and pyrolysis rate were found to improve the relative quality and quantity of pyrolyzate compounds detected by the IMS detector compare to earlier work. These improvements allowed a greater degree of confidence in the correlation of biological aerosols obtain in outdoor testing scenarios to a standard GC-IMS biological aerosol dataset. The airflow improvement allowed more biomarker compounds to be observed in the GC-IMS data domain for aerosols of Gram-negative Erwinia herbicola (EH) and ovalbumin protein as compared to previous studies. Minimal differences were observed for Gram-positive spores of Bacillus subtilis var. globigii (BG) from that of earlier work. Prior outdoor aerosol challenges dealt with the detection of one organism, either EH or BG. Biological aerosols were disseminated in a Western Canadian prairie and the Py-GC-IMS was tested for its ability to detect the biological aerosols. The current series of outdoor trials consisted of three different biological aerosol challenges. Forty-two trials were conducted and a simple area calculation of the GC-IMS data domain biomarker peaks correlated with the correct bioaerosol challenge in 30 trials. In another 7 trials, the status of an aerosol was determined to be biological in origin. Two additional trials had no discernible, unambiguous GC-IMS biological response, because they were black water sprays. Reproducible limits of detection were at a concentration of less than 0.5 bacterial analyte-containing particles per liter of air (ACPLA). In order to realize this low concentration, an aerosol concentrator was used to concentrate 2000 liters of air in 2.2 minutes. Previous outdoor aerosol trials have shown the Py-GC-IMS device to be a credible detector with response to determining the presence of a biological aerosol. The current series of outdoor trials has provided a platform to show that the Py-PC-IMS can provide information more specific than a biological or non-biological analysis to an aerosol when the time of dissemination is unknown to the operator. The Py-GC-IMS is shown to be able to discriminate between aerosols of a Gram-positive spore, a Gram-negative bacterium and a protein.

  18. Characterization of molecular mass ranges of two coal tar distillate fractions (creosote and anthracene oils) and aromatic standards by LD-MS, GC-MS, probe-MS and size-exclusion chromatography

    SciTech Connect

    T.J. Morgan; A. George; P. A'lvarez; M. Millan; A.A. Herod; R. Kandiyoti

    2008-09-15

    Laser-desorption mass spectrometry (LD-MS) method development was undertaken to improve estimates of mass ranges for complex hydrocarbon mixtures. A creosote oil, an anthracene oil, and a mixture of known polynuclear aromatic hydrocarbon (PAH) compounds were examined. The formation of cluster ions was possible without overloading the detector system. These multimer ions overlapped with higher-mass ion signals from the sample. However, careful balancing of sample concentration, laser power, total ion current, and delayed ion extraction appears to show high-mass materials without generating high-mass multimer (artifact) ions. It is possible to suppress the formation of cluster ions by keeping low target concentrations and, consequently, low gas phase concentrations formed by the laser pulse. The principal method used in this work was the fractionation of samples by planar chromatography followed by successive LD-MS analysis of the separated fractions directly from the chromatographic plates. This method separated the more abundant small molecules from the less abundant large molecules to permit the generation of their mass spectra independently, as well as reducing the concentration of sample by spreading over the PC-plate. The technique demonstrably suppressed multimer formation and greatly improved the reproducibility of the spectra. Results showed the presence of molecule ions in the ranges m/z 1000-2000 for the anthracene oil sample and m/z 600-1500 for the creosote oil sample, tailing off to m/z about 5,000. The creosote oil contained significantly less of this high-mass material than the anthracene oil sample, and in both cases, high-mass material was only present in low quantities. The method outlined in the paper appears directly applicable to the characterization of heavier coal and petroleum derived fractions. 44 refs., 14 figs., 3 tabs.

  19. Investigation of isomeric flavanol structures in black tea thearubigins using ultraperformance liquid chromatography coupled to hybrid quadrupole/ion mobility/time of flight mass spectrometry.

    PubMed

    Yassin, Ghada H; Grun, Christian; Koek, Jean H; Assaf, Khaleel I; Kuhnert, Nikolai

    2014-11-01

    Ultra performance liquid chromatography (UPLC) when coupled to ion mobility (IMS)/orthogonal acceleration time of flight mass spectrometry is a suitable technique for analyzing complex mixtures such as the black tea thearubigins. With the aid of this advanced instrumental analysis, we were able to separate and identify different isomeric components in the complex mixture which could previously not be differentiated by a conventional high performance liquid chromatography/tandem mass spectrometry. In this study, the difference between isomeric structures theasinensins, proanthocyanidins B-type and rutin (quercetin-3O-rutinoside) were studied, and these are present abundantly in many botanical sources. The differentiation between these structures was accomplished according to their acquired mobility drift times differing from the traditional investigations in mass spectrometry, where calculation of theoretical collisional cross sections allowed assignment of the individual isomeric structures. The present work demonstrates UPLC-IMS-MS as an efficient technology for isolating and separating isobaric and isomeric structures existing in complex mixtures discriminating between them according to their characteristic fragment ions and mobility drift times. Therefore, a rational assignment of isomeric structures in many phenolic secondary metabolites based on the ion mobility data might be useful in mass spectrometry-based structure analysis in the future. PMID:25395124

  20. High-performance liquid chromatography of amino acids, peptides and proteins. CIII. Mass transfer resistances in ion-exchange and dye-affinity chromatography of proteins.

    PubMed

    Johnston, A; Hearn, M T

    1990-07-20

    Adsorption equilibria and rate kinetics have been investigated for the binding of several proteins, with different molecular geometries, to several ion-exchange and dye-affinity chromatographic resins with varying pore size and protein accessibilities. The pore geometry was shown to play a significant role in the protein capacity and loadability of both the ion-exchange and dye-affinity resins. For example the Fractogel HW75-Cibacron Blue F3GA affinity sorbent had the greatest capacity for the small protein, lysozyme, compared to the other Fractogel HW-Cibacron Blue F3GA sorbents, and similarly, the ion-exchange resins, such as DEAE-Fractogel 65, bound more human serum albumin (HSA), as opposed to the larger protein, ferritin. The apparent diffusion of protein from the bulk phase to the ligands/ionic sites was calculated to be considerably restricted when the pore to protein size ratio was small, as is the case of DEAE Fractogel 65/ferritin system, and the dye-affinity Fractogel HW55/HSA system. In these circumstances, pore diffusivity was calculated to be up to 100-fold smaller than bulk diffusivity. PMID:2229222

  1. Fragmentation study of imatinib and characterization of new imatinib metabolites by liquid chromatography-triple-quadrupole and linear ion trap mass spectrometers.

    PubMed

    Marull, Marc; Rochat, Bertrand

    2006-03-01

    Imatinib (Gleevec) is an anticancer drug that inhibits specific protein kinases involved in cell proliferation. Whereas this drug is considered to have opened a new era, various mechanisms of resistance have been associated with imatinib relapse. Drug disposition in cancer cells including influx, efflux and drug metabolism is one mechanism that remains to be more thoroughly investigated. Moreover, recent genomic studies have revealed that some isozymes of cytochrome P450 (CYP) are possibly associated with the treatment outcome. Therefore, this research paper investigates the role of the activity of CYP1A1, 1A2, 1B1, 3A4, 4F2 and 4F3A/B on the fate of imatinib. First, a study of imatinib fragmentation was effected using electrospray triple-quadrupole and linear ion trap tandem mass spectrometers (MSn). Accurate mass determinations were performed at enhanced mass resolution for the identification of some product ions that were not predicted by two fragmentation softwares. Whereas the quadrupole MS was not designed for accurate mass measurement, delta mass errors were below 20 ppm. Then, a biotransformation study was effected in vitro. Imatinib metabolites were produced in microsomal incubations containing CYP isozymes. Imatinib and metabolites were extracted from incubation mixtures by protein precipitation, and supernatants were injected into a liquid chromatography equipment coupled with MS(n). Hydrophobic interaction liquid chromatography resolved one demethylated-, two hydroxy- and three N-oxide metabolites. Various rates of metabolite formation were observed between CYP isozymes. Liquid chromatography with deuterium oxide-containing mobile phase (H/D exchange) or incorporation of (18)O from H(2) (18)O added in the incubations was performed to elucidate the metabolite structure. Various MS(n) product scans (n < or = 4) were acquired on the linear ion trap or on the triple-quadrupole MS. Postulated structures of new metabolites are addressed. PMID:16470567

  2. Simultaneous determination of vitamins B1, B2, B6, and niacinamide in multivitamin pharmaceutical preparations by paired-ion reversed-phase high-pressure liquid chromatography.

    PubMed

    Kwok, R P; Rose, W P; Tabor, R; Pattison, T S

    1981-09-01

    A high-pressure liquid chromatographic procedure for the simultaneous determination of vitamins B1, B2, B6, and niacinamide in multivitamin pharmaceutical preparations was developed and evaluated. The method uses paired-ion reversed-phase partition chromatography for baseline separation of the four water-soluble vitamins. This method was applied to the analysis of a multivitamin and multivitamin-multimineral tablets, and a technique was developed to reduce vitamin adsorption by the minerals. The results obtained by this method were compared with those obtained by the official methods. It was concluded that this method is fast, accurate, specific, and suitable for routine quality control use. PMID:6101144

  3. Metabonomic Study of Biochemical Changes in Human Hair of Heroin Abusers by Liquid Chromatography Coupled with Ion Trap-Time of Flight Mass Spectrometry.

    PubMed

    Xie, Pu; Wang, Tie-Jie; Yin, Guo; Yan, Yan; Xiao, Li-He; Li, Qing; Bi, Kai-Shun

    2016-01-01

    Hair analysis is with the advantage of non-invasive collection and long surveillance window. The present study employed a sensitive and reliable liquid chromatography coupled with ion trap-time of flight mass spectrometry method to study the metabonomic characters in the hair of 58 heroin abusers and 72 non-heroin abusers. Results indicated that certain endogenous metabolites, such as sorbitol and cortisol, were accelerated, and the level of arachidonic acid, glutathione, linoleic acid, and myristic acid was decreased in hair of heroin abusers. The metabonomic study is helpful for further understanding of heroin addiction and clinical diagnosis. PMID:26445826

  4. Use of solid-phase microextraction for the detection of acetic acid by ion-trap gas chromatography-mass spectrometry and application to indoor levels in museums.

    PubMed

    Godoi, Ana F L; Van Vaeck, Luc; Van Grieken, René

    2005-03-01

    A simple and efficient method using solid-phase microextraction (SPME) and gas chromatography-ion trap mass spectrometry (GC-ITMS) was developed for the analysis of acetic acid in air. The choice of the SPME fibre revealed to be critical as well as the sampling and desorption time. A dilution vessel was used for calibration. The precision of the method was found to be 4.7% relative standard deviation (RSD) and the detection limit 5.7 microg m(-3). The SPME-GC-MS technique was applied to the analysis of acetic acid in museum atmospheres. PMID:15844539

  5. Chelation ion chromatography of alkaline earth and transition metals a using monolithic silica column with bonded N-hydroxyethyliminodiacetic acid functional groups.

    PubMed

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Jones, Phil; Paull, Brett

    2013-02-01

    A commercially available porous silica monolithic column (Onyx Monolithic Si, 100 mm×4.6 mm I.D.) was 'in-column' covalently functionalised with 2-hydroxyethyliminodiacetic acid (HEIDA) groups, and applied to the simultaneous and rapid separation of alkaline earth and transition metal ions, using high-performance chelation ion chromatography (HPCIC). With a 0.3mM dipicolinic acid (DPA) containing eluent, the baseline separation of various common transition and heavy metal ions and the four alkaline earth metal ions could be achieved in under 14 min with a flow rate of just 0.8 mL/min. Detection was achieved using spectrophotometric detection at 540 nm after post-column reaction (PCR) with 4-(2-pyridylazo)-resorcinol (PAR). Significant effects from variation of eluent nature, concentration and temperature upon selectivity and retention were demonstrated with the new monolithic silica chelating phase. Under optimised conditions (0.165 M LiNO(3) eluent, pH 2.5), peak efficiencies of 54,000, 60,000 and 64,000 N/m, for Zn(2+), Mn(2+) and Cd(2+), respectively, were recorded, far exceeding that previously reported for IDA based chelation ion exchange columns. PMID:23298846

  6. Determination of trace labile copper in environmental waters by magnetic nanoparticle solid phase extraction and high-performance chelation ion chromatography.

    PubMed

    Wei, Z; Sandron, S; Townsend, A T; Nesterenko, P N; Paull, B

    2015-04-01

    Cobalt magnetic nanoparticles surface functionalised with iminodiacetic acid were evaluated as a nano-particulate solid phase extraction absorbent for copper ions (Cu(2+)) from environmental water samples. Using an external magnetic field, the collector nanoparticles could be separated from the aqueous phase, and adsorbed ions simply decomplexed using dilute HNO3. Effects of pH, buffer concentration, sample and sorbent volume, extraction equilibrium time, and interfering ion concentration on extraction efficiency were investigated. Optimal conditions were then applied to the extraction of Cu(2+) ions from natural water samples, prior to their quantitation using high-performance chelation ion chromatography. The limits of detection (LOD) of the combined extraction and chromatographic method were ~0.1 ng ml(-1), based upon a 100-fold preconcentration factor (chromatographic performance; LOD=9.2 ng ml(-1) Cu(2+)), analytical linear range from 20 to 5000 ng mL(-1), and relative standard deviations=4.9% (c=1000 ng ml(-1), n=7). Accuracy and precision of the combined approach was verified using a certified reference standard estuarine water sample (SLEW-2) and comparison of sample determinations with sector field inductively coupled plasma mass spectrometry. Recoveries from the addition of Cu(2+) to impacted estuarine and rain water samples were 103.5% and 108.5%, respectively. Coastal seawater samples, both with and without prior UV irradiation and dissolved organic matter removal were also investigated using the new methodology. The effect of DOM concentration on copper availability was demonstrated. PMID:25640140

  7. Quantitative analysis of exogenous peptides in plasma using immobilized enzyme cleavage and gas chromatography-mass spectrometry with negative ion chemical ionization.

    PubMed

    Márquez, C D; Lee, M L; Weintraub, S T; Smith, P C

    1997-10-24

    A method is presented for the analysis of peptides in plasma at picomole to femtomole levels. Peptides are isolated from plasma by solid-phase extraction, the peptide of interest is purified by reversed-phase high-performance liquid chromatography (HPLC) and selectively digested using immobilized trypsin or chymotrypsin to yield specific di- or tripeptides. These di- and tripeptides are esterified using heptafluorobutyric anhydride, alkylated with pentafluorobenzyl bromide, then quantified by gas chromatography-mass spectrometry with negative ion chemical ionization. This method has been evaluated for a model synthetic heptapeptide, using a deuterium labeled analog as an internal standard. The half-life of the heptapeptide in human plasma was found to be 2 min. Extraction efficiencies of a tritiated peptide of similar size to the heptapeptide, [3H]DSLET, from plasma using either C18 or strong cation-exchange columns were 85+/-3 and 70+/-2%, respectively. Quantitation of fragments from the heptapeptide indicated that the analysis was linear from 1-50 ng of the heptapeptide per ml of plasma. This method was subsequently employed for pharmacokinetic studies of the biologically active peptide Met-enkephalin-Arg-Gly-Leu, where linearity was obtained from 50 to 1000 ng/ml in rat plasma. This method demonstrated negligible side reaction by-products due to autolysis, and has potential for extensive use given the wide availability of gas chromatography-mass spectrometry. PMID:9390710

  8. Gas Chromatography/Atmospheric Pressure Chemical Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Pyrolysis Oil from German Brown Coal

    PubMed Central

    Zuber, Jan; Kroll, Marius M.; Rathsack, Philipp; Otto, Matthias

    2016-01-01

    Pyrolysis oil from the slow pyrolysis of German brown coal from Schöningen, obtained at a temperature of 500°C, was separated and analyzed using hyphenation of gas chromatography with an atmospheric pressure chemical ionization source operated in negative ion mode and Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FT-ICR-MS). Development of this ultrahigh-resolving analysis method is described, that is, optimization of specific GC and APCI parameters and performed data processing. The advantages of GC-APCI-FT-ICR-MS hyphenation, for example, soft ionization, ultrahigh-resolving detection, and most important isomer separation, were demonstrated for the sample liquid. For instance, it was possible to separate and identify nine different propylphenol, ethylmethylphenol, and trimethylphenol isomers. Furthermore, homologous series of different acids, for example, alkyl and alkylene carboxylic acids, were verified, as well as homologous series of alkyl phenols, alkyl dihydroxy benzenes, and alkoxy alkyl phenols. PMID:27066076

  9. Gas Chromatography/Atmospheric Pressure Chemical Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Pyrolysis Oil from German Brown Coal.

    PubMed

    Zuber, Jan; Kroll, Marius M; Rathsack, Philipp; Otto, Matthias

    2016-01-01

    Pyrolysis oil from the slow pyrolysis of German brown coal from Schöningen, obtained at a temperature of 500°C, was separated and analyzed using hyphenation of gas chromatography with an atmospheric pressure chemical ionization source operated in negative ion mode and Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FT-ICR-MS). Development of this ultrahigh-resolving analysis method is described, that is, optimization of specific GC and APCI parameters and performed data processing. The advantages of GC-APCI-FT-ICR-MS hyphenation, for example, soft ionization, ultrahigh-resolving detection, and most important isomer separation, were demonstrated for the sample liquid. For instance, it was possible to separate and identify nine different propylphenol, ethylmethylphenol, and trimethylphenol isomers. Furthermore, homologous series of different acids, for example, alkyl and alkylene carboxylic acids, were verified, as well as homologous series of alkyl phenols, alkyl dihydroxy benzenes, and alkoxy alkyl phenols. PMID:27066076

  10. Characterisation of anthocyanins in red cabbage using high resolution liquid chromatography coupled with photodiode array detection and electrospray ionization-linear ion trap mass spectrometry.

    PubMed

    Arapitsas, Panagiotis; Sjöberg, Per J R; Turner, Charlotta

    2008-07-01

    The aim of this work was to analyse and tentatively identify anthocyanin species in red cabbage using HPLC/DAD-ESI/Qtrap MS. The extraction was realized by using a pressurized liquid technique and the separation of the pigments was achieved by a high resolution liquid chromatography system with a 1.8μm particles C-18 column. Photodiode array detection was employed to determine the UV/Vis spectral characteristic of the pigments. Electrospray ionization-linear ion trap mass spectrometry allowed the specific determination of the fragmentation patterns of the anthocyanins, by performing different ion scan modes. Twenty four anthocyanins were separated and identified, all having cyanidin as aglycon, represented as mono- and/or di-glycoside, and acylated, or not, with aromatic and aliphatic acids. Nine anthocyanins were identified for the first time in red cabbage. PMID:26054284

  11. Simultaneous doping analysis of main urinary metabolites of anabolic steroids in horse by ion-trap gas chromatography-tandem mass spectrometry.

    PubMed

    Yamada, Masayuki; Aramaki, Sugako; Kurosawa, Masahiko; Kijima-Suda, Isao; Saito, Koichi; Nakazawa, Hiroyuki

    2008-09-01

    The use of anabolic steroids in racehorses is strictly regulated. We have developed a method for the simultaneous analysis of 11 anabolic steroids: fluoxymesterone, 17alpha-methyltestosterone, mestanolone, methandienone, methandriol, oxymetholone, boldenone, furazabol, methenolone, nandrolone, and stanozolol, for possible application to a doping test in racehorses. We selected 15 kinds of target substances for a doping test from the main metabolites of these anabolic steroids, and established a method for simultaneous analysis. Urine was hydrolyzed and subjected to solid-phase extraction. Then, the residue from the extracts was derivatized by trimethylsilylation. The derivatized samples were subjected to ion-trap gas chromatography-tandem mass spectrometry, and their mass chromatograms and product ion spectra were obtained. The limit of detection of the target substances was 5-50 ng/mL, and the mean recovery and coefficient of variation were 71.3-104.8% and 1.1-9.5%, respectively. PMID:18781036

  12. The identification and quantification of a high molecular weight light stabilizer in polycarbonate by application of an online coupling of size exclusion chromatography in stopped flow mode with pyrolysis gas chromatography time of flight mass spectroscopy.

    PubMed

    Brander, Eric; Wold, Christian

    2014-10-01

    The identification and quantification of a high molecular weight light stabilizer (Uvinul 3030™) in an unknown polycarbonate sample was achieved through the application of SEC-Py-TOF-GCMS. A size exclusion column optimized to achieve resolution in the lower mass range was applied to allow the fractionation of an individual additive peak. A commercially available sampling interface was operated in stop flow mode and fractions were pyrolyzed to allow chromatographic separation of the fragments of the otherwise non-volatile stabilizer. After identification on the basis of accurate mass and elemental composition of the additive the quantification was compared using the available SEC-UV and SEC-PY-GC-TOFMS data. The resulting method provided a high degree of certainty in identification and flexibility in quantification expected to be applicable to other additives of similar volatilities or functional class. PMID:25160954

  13. Determination of human insulin and its analogues in human blood using liquid chromatography coupled to ion mobility mass spectrometry (LC-IM-MS).

    PubMed

    Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2014-01-01

    The qualitative and quantitative determination of insulin from human blood samples is an emerging topic in doping controls as well as in other related disciplines (e.g. forensics). Beside the therapeutic use, insulin represents a prohibited, performance enhancing substance in sports drug testing. In both cases accurate, sensitive, specific, and unambiguous determination of the target peptide is of the utmost importance. The challenges concerning identifying insulins in blood by liquid chromatography coupled to ion mobility mass spectrometry (LC-IM-MS) are detecting the basal concentrations of approximately 0.2 ng/mL and covering the hyperinsulinaemic clamps at > 3 ng/mL simultaneously using up to 200 μL of plasma or serum. This is achieved by immunoaffinity purification of the insulins with magnetic beads and subsequent separation by micro-scale liquid chromatography coupled to ion mobility / high resolution mass spectrometry. The method includes human insulin as well as the synthetic or animal analogues insulin aspart, glulisine, glargine, detemir, lispro, bovine, and porcine insulin. The method validation shows reliable results considering specificity, limit of detection (0.2 ng/mL except for detemir: 0.8 ng/mL), limit of quantification (0.5 ng/mL for human insulin), precision (CV < 20%), linearity (r > 0.99), recovery, accuracy (>90%), robustness (plasma/serum), and ion suppression. For quantification of human insulin a labelled internal standard ([[(2) H10 ]-Leu(B6,B11,B15,B17) ] - human Insulin) is introduced. By means of the additional ion mobility separation of the different analogues, the chromatographic run time is shortened to 8 min without losing specificity. As proof-of-concept, the procedure was successfully applied to different blood specimens from diabetic patients receiving recombinant synthetic analogues. PMID:25219675

  14. An optimized method for the determination of perfluorooctanoic acid, perfluorooctane sulfonate and other perfluorochemicals in different matrices using liquid chromatography/ion-trap mass spectrometry.

    PubMed

    Dolman, Sebastiaan; Pelzing, Matthias

    2011-07-15

    Perfluorochemicals (PFC's) are widely spread in the environment and have been detected in blood of wildlife and humans world-wide. Recently, various toxic effects of PFC's in laboratory rats have been demonstrated, resulting in increased government concerns regarding the presence of PFC's in the environment and the implications they have on human health. In the last decade, various analytical methods have been developed for the analysis of PFC's in different matrices whereby the majority of methods have utilised liquid chromatography coupled with mass spectrometry (LC-MS). Here we describe an optimized method for the quantitation of PFC's, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), in food packaging, polytetrafluoroethylene (PTFE) sealant tape and drinking water. The method involved PFC's extraction via off-line SPE followed by separation using reversed-phase liquid chromatography on a Phenyl-Hexyl column coupled with ion-trap (IT) mass spectrometric detection. The optimized approach minimized ion-suppression effects commonly seen with conventional elution buffers, improving detection limits down to 25 pg/mL and allowed effective quantitation down to 50 pg/mL for PFOA and PFOS. The optimized LC-MS method detected PFOA and other PFC's in microwave popcorn packaging and PFOA in PTFE sealant tape in the low μg/kg. In all samples, PFOS was not detected. PMID:21700512

  15. Residues from low-order energetic materials: the comparative performance of a range of sampling approaches prior to analysis by ion chromatography.

    PubMed

    Szomborg, Katarzyna; Jongekrijg, Fleur; Gilchrist, Elizabeth; Webb, Tony; Wood, Dan; Barron, Leon

    2013-12-10

    A quantitative study of common forensic evidence collection devices for the recovery of low-explosive residues from non-porous glass and plastic is presented herein. Swabbing materials including cotton, rayon, Nomex(®) (poly(isophthaloylchloride/m-phenylenediamine)), Teflon/Teflon-coated fibreglass (polytetrafluoroethylene) and adhesive-coated tapes were used to collect known quantities of up to 14 forensically relevant inorganic and organic anion and cation species from both surfaces. Analysis was performed using two validated ion chromatography methods. This study revealed that all swabs and surfaces contributed highly variable levels of interfering ionic species and that swabbing materials showed variance in the quantities and total number of analytes recovered from both surfaces. Teflon and Nomex(®) materials demonstrated the most promise due to their ability to collect and release analytes into simple extraction solvents as well as displaying relatively low endogenous interference. In parallel, the ability to extract residue directly from both surfaces via the addition of a suitable extraction solvent was investigated instead of swabbing. This work highlights that direct solvent extraction from a surface should be considered as an alternative approach, especially for small areas or objects. To the best of our knowledge, this work represents the most comprehensive study of the efficiencies of sample collection technologies for low-explosive residues prior to analysis by ion chromatography. PMID:24314502

  16. Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring

    ERIC Educational Resources Information Center

    Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

    2005-01-01

    Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining

  17. Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring

    ERIC Educational Resources Information Center

    Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

    2005-01-01

    Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining…

  18. Methodology for porting retention prediction data from old to new columns and from conventional-scale to miniaturised ion chromatography systems.

    PubMed

    Ng, Boon K; Shellie, Robert A; Dicinoski, Greg W; Bloomfield, Carrie; Liu, Yan; Pohl, Christopher A; Haddad, Paul R

    2011-08-12

    Several procedures are available for simulating and optimising separations in ion chromatography (IC), based on the application of retention models to an extensive database of analyte retention times on a wide range of columns. These procedures are subject to errors arising from batch-to-batch variability in the synthesis of stationary phases, or when using a column having a different diameter to that used when the database was acquired originally. Approaches are described in which the retention database can be recalibrated to accommodate changes in the stationary phase (ion-exchange selectivity coefficient and ion-exchange capacity) or in the column diameter which lead to changes in phase ratio. The entire database can be recalibrated for all analytes on a particular column by performing three isocratic separations with two analyte ions. The retention data so obtained are then used to derive a "porting" equation which is employed to generate the required simulated separation. Accurate prediction of retention times is demonstrated for both anions and cations on 2mm and 0.4mm diameter columns under elution conditions which consist of up to five sequential isocratic or linear gradient elution steps. The proposed approach gives average errors in retention time prediction of less than 3% and the correlation coefficient was 0.9849 between predicted and observed retention times for 344 data points comprising 33 anionic or cationic analytes, 5 column internal diameters and 8 complex elution profiles. PMID:21741652

  19. Diagnostic filtering to screen polycyclic polyprenylated acylphloroglucinols from Garcinia oblongifolia by ultrahigh performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry.

    PubMed

    Zhang, Hong; Zheng, Dan; Li, Hao-Hao; Wang, Hui; Tan, Hong-Sheng; Xu, Hong-Xi

    2016-03-17

    A novel multistage MS approach, insource collision-induced dissociation (CID) combined with Time Aligned Parallel (TAP) fragmentation, was established to study the fragmentation behavior of polycyclic polyprenylated acylphloroglucinols (PPAPs), which could provide a more reliable fragmentation relationship between precursor and daughter ions. The diagnostic ions for different subtypes of PPAPs and their fragmentation behaviors have been summarized. Moreover, a new and reliable multidimensional analytical workflow that combines ultrahigh performance liquid chromatography (UHPLC), data-independent mass spectrometry (MS(E)), and tandem MS with ion mobility (IM) has been optimized and established for the analysis of PPAPs in the plant Garcinia oblongifolia by diagnostic filtering. Diagnostic fragment ions were used to selectively screen PPAPs from extracts, whereas IM coupled to MS was used to maximize the peak capacity. Under the optimized UHPLC-IM-MS(E) and UHPLC-IM-MS/MS method, 140 PPAPs were detected from the crude extract of G. oblongifolia, and 10 of them were unambiguously identified by comparing them to the reference compounds. Among those PPAPs, 7 pairs of coeluting isobaric PPAPs that were indistinguishable by conventional UHPLC-HRMS alone, were further resolved using UHPLC-IM-MS. It is anticipated that the proposed method will be extended to the rapid screening and characterization of the other targeted or untargeted compounds, especially these coeluting isomers in complex samples. PMID:26920776

  20. [Screening method for the determination of 199 pesticides in agricultural products by gas chromatography/ion trap mass spectrometry (GC/MS/MS)].

    PubMed

    Hirahara, Yoshichika; Kimura, Mika; Inoue, Tomoko; Uchikawa, Seiji; Otani, Shoji; Hirose, Hideaki; Suzuki, Sosuke; Uchida, Yukinori

    2006-10-01

    A screening method is described for determining 200 pesticides, except dimethipin, divided into four groups by means of gas chromatography/tandem mass spectrometry (GC/MS/MS) using an ion trap mass spectrometer equipped with automated gain control (AGC). The quantitation limit for 194 pesticides was 0.01 mg/kg on a crop basis, except for allidochlor, dimethoate, hexythiazox, methamidophos and triadimenol. The calibration curve of each pesticide was linear in the range of 0.04-5.0 microg/mL. One hundred and ninety-nine pesticides were added to matrix of potato, spinach, cabbage, apple, orange, soybean and unpolished rice at twice the limits of quantitation. The recoveries of 194 pesticides from all crops were satisfactory (50-150%) for screening purposes. Although some pesticides in apple and orange were not determined by selected ion monitoring (SIM) analysis at the limits of quantitation, all of them were identified by ion-trap GC/MS/MS at the same concentration. Thus, the ion trap GC/MS/MS technique is useful for the screening of residual pesticides present at low levels in agricultural products. PMID:17128871

  1. A study of the analytical behaviour of selected new molecular entities using electrospray ionisation ion trap mass spectrometry, liquid chromatography, gas chromatography and polarography and their determination in serum at therapeutic concentrations.

    PubMed

    Rodríguez Robledo, Virginia; Smyth, W Franklin

    2008-08-15

    This paper provides analytical chemical information on selected new molecular entities (NMEs) which are drugs that have recently been approved by the FDA. These are the antiretroviral drugs, atazanavir, indinavir and emtricitabine, the antibacterial gemifloxacin, rosuvastatine which is a cholesterol-lowering drug, the anti-cancer drug gefitinib and aprepitant for neurological disorders. Electrospray ionisation-quadrupole ion trap mass spectrometry (ESI-MS(n)) was employed to generate tandem mass spectrometric (MS(2)) data of the drugs studied and structural assignments of product ions were supported by quadrupole time-of-flight mass spectrometry (QToF-MS/MS). These fragmentation studies were then utilised in the development and validation of a specific and sensitive liquid chromatographic method (LC-ESI-MS(2)) to identify and determine these drugs at therapeutic concentration levels in serum after a single protein precipitation procedure with acetonitrile. In addition, this method was compared to the application of gas liquid chromatography-flame ionisation detection (GLC-FID) and differential pulse polarography (DPP) for the analysis of these NMEs in serum. PMID:18620927

  2. Identification of 1-hydroxypyrene glucuronide in tissue of marine polychaete Nereis diversicolor by liquid chromatography/ion trap multiple mass spectrometry.

    PubMed

    Giessing, Anders M B; Lund, Torben

    2002-01-01

    1-Hydroxypyrene glucuronide is identified as the single major aqueous metabolite of the tetracyclic aromatic hydrocarbon pyrene, in tissue from a deposit-feeding marine polychaete, Nereis diversicolor. Identification was performed using an ion trap mass spectrometer fitted with an atmospheric pressure chemical ionization (APCI) probe and connected to a high-performance liquid chromatography/diode array detector (HPLC/DAD) system. Besides 1-hydroxypyrene, the 339-nm UV trace of tissue samples from pyrene-exposed worms showed only one dominant peak that could be related to pyrene metabolism. Negative APCI-MS of this supposed 1- hydroxypyrene conjugate gave a characteristic signal at m/z 429 corresponding to the molecular ion of 1-hydroxypyrene glucuronide plus eluent adducts ([M - H + 2H(2)O](-)). Fragmentation pathways were studied by isolating the abundant ion at m/z 429 in the ion trap and performing multiple mass spectrometric experiments (MS(n)). The fragmentations observed were consistent with the proposed identification. Two low intensity LC peaks that could be related to pyrene metabolism by their DAD absorption spectra were also present in the 339-nm UV chromatogram of tissue samples. However, these peaks could not be identified by their mass spectra in negative ion mode due to ion suppression by very abundant co-eluting impurities. The present method shows that LC/MS(n) is a fast and useful analytical tool for identification of aqueous polycyclic aromatic hydrocarbon biotransformation products in samples from relatively small marine invertebrates with limited sample preparation. PMID:12203242

  3. High-performance liquid chromatography with paired ion electrospray ionization (PIESI) tandem mass spectrometry for the highly sensitive determination of acidic pesticides in water.

    PubMed

    Xu, Chengdong; Armstrong, Daniel W

    2013-08-20

    A novel method based on the paired ion electrospray ionization (PIESI) mass spectrometry has been developed for determination of acidic pesticides at ultratrace levels in surface and ground waters. The proposed approach provides greatly enhanced sensitivity for acidic pesticides and overcomes the drawbacks of the less sensitive negative ion mode ESI-MS. The limits of detection (LODs) of 19 acidic pesticides were evaluated with four types of dicationic ion-pairing reagent (IPR) in both single ion monitoring (SIM) and selected reaction monitoring (SRM) mode. The LOD of 19 pesticides obtained with the use the optimal dicationic ion-pairing reagent ranged from 0.6pg to 19pg, indicating the superior sensitivity provided by this method. The transition pathways for different pesticide-IPR complexes during the collision induced dissociation (CID) were identified. To evaluate and eliminate any matrix effects and further decrease the detection limits, off-line solid-phase extraction (SPE) was performed for DI water and a river water matrix spiked with 2000ng L(-1) and 20ng L(-1) pesticides standards respectively, which showed an average percent recovery of 93%. The chromatographic separation of the acidic pesticides was conducted by high-performance liquid chromatography (HPLC) using a C18 column (250mm×2.1mm) in the reversed phase mode using linear gradient elution. The optimized HPLC-PIESI-MS/MS method was utilized for determination of acidic pesticide at ng L(-1) level in stream/pond water samples. This experimental approach is 1-3 orders of magnitude more sensitive for these analytes than other reported methods performed in the negative ion mode. PMID:23910961

  4. Applying Chromatography.

    ERIC Educational Resources Information Center

    Klein, Jessie W.; Patev, Paul

    1998-01-01

    Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

  5. Study of ion suppression for phenolic compounds in medicinal plant extracts using liquid chromatography-electrospray tandem mass spectrometry.

    PubMed

    Faccin, H; Viana, C; do Nascimento, P C; Bohrer, D; de Carvalho, L M

    2016-01-01

    A systematic study on the various sources of ion suppression in UHPLC-MS-MS analysis was carried out for 24 phenolic antioxidants in 6 different extracts of medicinal plants from Amazonia. The contributions of matrix effects, mobile-phase additives, analyte co-elution and electric charge competition during ionization to the global ion suppression were evaluated. Herein, the influence of mobile-phase additives on the ionization efficiency was found to be very pronounced, where ion suppression of approximately 90% and ion enhancement effects greater than 400% could be observed. The negative effect caused by the wrong choice of internal standard (IS) on quantitative studies was also evaluated and discussed from the perspective of ion suppression. This work also shows the importance of performing studies with this approach even for very similar matrices, such as varieties of medicinal plants from the same species, because different effects were observed for the same analyte. PMID:26709070

  6. Study of fungal degradation products of polycyclic aromatic hydrocarbons using gas chromatography with ion trap mass spectrometry detection.

    PubMed

    Cajthaml, Toms; Mder, Monika; Kacer, Petr; Sasek, Vclav; Popp, Peter

    2002-10-18

    Representatives of polycyclic aromatic hydrocarbons (PAHs) were degraded by ligninolytic fungus Irpex lacteus. The products were analyzed by GC-Ion trap mass spectrometry. The combination of full scan mass spectra, product ion scans (MS-MS) and derivatization of the degradation products of anthracene, phenanthrene, fluoranthene and pyrene provided further insight in the degradation mechanism initiated by I. lacteus. Particularly, the product ion scans enabled the interpretation of unknown degradation products, even though they were only produced at trace level. Most of the structures suggested were later confirmed with authentic standards. PMID:12458938

  7. Sensitive determination of acidic drugs and triclosan in surface and wastewater by ion-pair reverse-phase liquid chromatography/tandem mass spectrometry.

    PubMed

    Quintana, José Benito; Reemtsma, Thorsten

    2004-01-01

    A new method is presented for the determination of 12 acidic pharmaceuticals (non-steroidal anti-inflammatory drugs and bezafibrate), including two metabolites from aqueous samples, together with triclosan as a personal care product. Ion-pair liquid chromatography (IP-LC) with electrospray ionisation tandem mass spectrometry (ESI-MS) in the negative ion mode was employed. The ion-pairing agent (tri-n-butylamine) increased the signal intensity for all acidic analytes and detection limits of 6-200 ng/L were obtained by multiple reaction monitoring. This allows analysis of wastewater samples by direct injection into the LC/MS system without the need for a preceding enrichment step. When combined with a solid-phase extraction (SPE) step, limits of quantification between 0.15 and 11 ng/L were obtained from 100-mL sample volumes, which is adequate for most applications. The occurrence of matrix effects was studied and standard addition was required for reliable quantification after SPE from wastewater. The method was finally applied to surface and wastewaters, with analyte concentrations ranging from below the detection limit up to 5.5 microg/L. PMID:15052558

  8. Organic solvent and temperature-enhanced ion chromatography-high resolution mass spectrometry for the determination of low molecular weight organic and inorganic anions.

    PubMed

    Gilchrist, Elizabeth S; Nesterenko, Pavel N; Smith, Norman W; Barron, Leon P

    2015-03-20

    There has recently been increased interest in coupling ion chromatography (IC) to high resolution mass spectrometry (HRMS) to enable highly sensitive and selective analysis. Herein, the first comprehensive study focusing on the direct coupling of suppressed IC to HRMS without the need for post-suppressor organic solvent modification is presented. Chromatographic selectivity and added HRMS sensitivity offered by organic solvent-modified IC eluents on a modern hyper-crosslinked polymeric anion-exchange resin (IonPac AS18) are shown using isocratic eluents containing 5-50 mM hydroxide with 0-80% methanol or acetonitrile for a range of low molecular weight anions (<165 Da). Comprehensive experiments on IC thermodynamics over a temperature range between 20-45 °C with the eluent containing up to 60% of acetonitrile or methanol revealed markedly different retention behaviour and selectivity for the selected analytes on the same polymer based ion-exchange resin. Optimised sensitivity with HRMS was achieved with as low as 30-40% organic eluent content. Analytical performance characteristics are presented and compared with other IC-MS based works. This study also presents the first application of IC-HRMS to forensic detection of trace low-order anionic explosive residues in latent human fingermarks. PMID:25732588

  9. Ion chromatography/inductively coupled plasma mass spectrometry for simultaneous determination of glyphosate, glufosinate, fosamine and ethephon at nanogram levels in water.

    PubMed

    Guo, Zhong-Xian; Cai, Qiantao; Yang, Zhaoguang

    2007-01-01

    This paper describes the first approach that simultaneously quantifies four polar, water-soluble organophosphorus herbicides, i.e., glyphosate, glufosinate, fosamine and ethephon, at nanogram levels in environmental waters. The target herbicides were separated completely by ion chromatography (IC) on a polymer anion-exchange column, Dionex IonPac AS16 (4.0 mm x 250 mm), with 30 mM citric acid flowing at 0.70 mL min(-1) as the eluent. On-line inductively coupled plasma mass spectrometry (ICP-MS) using a quadrupole mass spectrometer was employed as a sensitive and selective detector of the effluents. Various parameters affecting the separation and detection were systematically examined and optimized. Detection limits of the herbicides achieved with the proposed IC/ICP-MS method were 1.1-1.4 microg L(-1) (as compound) based on a 500-microL sample injection. Matrix anions, metal ions, phosphate, polyphosphates, non-polar and other polar organophosphorus pesticides showed no interference. The developed method was validated using reservoir water, treated water and NEWater samples spiked at the level of 10-25 microg L(-1) with satisfactory recoveries (95-109%). It is applicable to the simultaneous determination of microg L(-1) concentrations of the herbicides in polluted water. PMID:17443488

  10. Rapid speciation and determination of vanadium compounds using ion-pair reversed-phase ultra-high-performance liquid chromatography inductively coupled plasma-sector field mass spectrometry.

    PubMed

    Kilibarda, Nikola; Afton, Scott E; Harrington, James M; Yan, Fei; Levine, Keith E

    2013-08-23

    Environmental vanadium contamination is a potential concern to public health, as evidenced by its place on the U.S. Environmental Protection Agency Drinking Water Contaminant Candidate List as a priority contaminant. Vanadium toxicity varies significantly between different oxidation states; therefore, it is crucial to be able to monitor the speciation of vanadium in environmental samples. In this study, a novel method is described that utilizes ion-pair reversed-phase ultra-high-performance liquid chromatography with inductively coupled plasma-sector field mass spectrometry (IP-RP-UHPLC-ICP-SFMS) to separate vanadyl and vanadate ions and resolve a major polyatomic spectral interference ((35)Cl(16)O(+)) in less than a minute. Detection limits were obtained in the low ngL(-1) (part per trillion) range with linear calibrations across several orders of magnitude (50ngL(-1)-100μgL(-1)). The mechanism of chromatographic retention was elucidated through investigation of the role of ethylenediaminetetraacetic acid, tetrabutylammonium ion and pH on elution. The optimized method was then applied to the speciation of vanadium in local lake water samples. PMID:23871564

  11. Quantitative determination of trace concentrations of tetracycline and sulfonamide antibiotics in surface water using solid-phase extraction and liquid chromatography/ion trap tandem mass spectrometry.

    PubMed

    Yang, Shinwoo; Cha, Jongmun; Carlson, Kenneth

    2004-01-01

    The occurrence of human and veterinary pharmaceutical compounds in surface waters (e.g. streams, lakes and reservoirs) is an important emerging environmental issue. There is a need for robust, sensitive and reliable analytical methods for measuring these compounds in a variety of natural water and wastewater matrices. This paper describes a method for the determination of seven tetracycline (TC) and six sulfonamide (SA) compounds in pristine and wastewater-influenced surface water using solid-phase extraction, and LCQ Duo ion trap liquid chromatography/tandem mass spectrometry (LC/MS/MS) with positive electrospray ionization (ESI(+)) and selected reaction monitoring (SRM). The seven TCs and six SAs analyzed using this method include oxytetracycline (OTC), chlortetracycline (CTC), tetracycline (TC), democlocycline (DMC), doxycycline (DXC), meclocycline (MCC), minocycline (MNC), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethazine (SMT), sulfachloropyridazine (SCP), sulfamethoxazole (SMX), and sulfadimethoxane (SDM). This study discusses the effects of flow rate, LC column diameter and LC column temperature on UV and/or mass peak quality of the different analytes. Several product ions for MS/MS detection have been identified and compared for ion trap and triple quadrupole LC/MS/MS instruments. Statistical analysis for determination of the method detection limit (MDL), accuracy and precision of the method is described. Matrix effects are evaluated in deionized, pristine and wastewater-influenced river water. The method is applied to evaluate the occurrence of these compounds in a small watershed in northern Colorado. PMID:15317045

  12. Mass Spectrometry Parameters Optimization for the 46 Multiclass Pesticides Determination in Strawberries with Gas Chromatography Ion-Trap Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Fernandes, Virgínia C.; Vera, Jose L.; Domingues, Valentina F.; Silva, Luís M. S.; Mateus, Nuno; Delerue-Matos, Cristina

    2012-12-01

    Multiclass analysis method was optimized in order to analyze pesticides traces by gas chromatography with ion-trap and tandem mass spectrometry (GC-MS/MS). The influence of some analytical parameters on pesticide signal response was explored. Five ion trap mass spectrometry (IT-MS) operating parameters, including isolation time (IT), excitation voltage (EV), excitation time (ET), maximum excitation energy or " q" value (q), and isolation mass window (IMW) were numerically tested in order to maximize the instrument analytical signal response. For this, multiple linear regression was used in data analysis to evaluate the influence of the five parameters on the analytical response in the ion trap mass spectrometer and to predict its response. The assessment of the five parameters based on the regression equations substantially increased the sensitivity of IT-MS/MS in the MS/MS mode. The results obtained show that for most of the pesticides, these parameters have a strong influence on both signal response and detection limit. Using the optimized method, a multiclass pesticide analysis was performed for 46 pesticides in a strawberry matrix. Levels higher than the limit established for strawberries by the European Union were found in some samples.

  13. Ultra-high performance liquid chromatography with linear ion trap-Orbitrap hybrid mass spectrometry combined with a systematic strategy based on fragment ions for the rapid separation and characterization of components in Stellera chamaejasme extracts.

    PubMed

    Wang, Zhixin; Qu, Yang; Wang, Li; Zhang, Xiaozhe; Xiao, Hongbin

    2016-04-01

    Stellera chamaejasme, a famous toxic herb, has been used in traditional Chinese medicine to treat various diseases. For decades, increasing attention in modern pharmacological studies has been drawn to S. chamaejasme because of its potential anti-tumor, anti-virus, and anti-fungus activities. However, due to the intrinsic complexity of chemical constitutes, hardly any investigations formed an overall recognition for the chemical profiles of this herb. In this study, a rapid and sensitive ultra-high performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry method was developed to characterize the chemical components of S. chamaejasme extracts. Based on optimized ultra-high performance liquid chromatography and mass spectrometry conditions and systematic fragment ions-based strategy, a total of 47 components including flavones, diterpenes, coumarins, and lignans were simultaneously detected and identified or tentatively identified for the first time. The MS(n) fragmentation patterns of all the characterized compounds in positive or negative electrospray ionization modes were also explored and summarized. These results provided essential data for further pharmacological research on S. chamaejasme. Moreover, the method was demonstrated to be an efficient tool for rapid qualitative analysis of secondary metabolites from natural resources. PMID:26861765

  14. Determination of testosterone in plasma from men by gas chromatography/mass spectrometry, with high-resolution selected-ion monitoring and metastable peak monitoring

    SciTech Connect

    Finlay, E.M.; Gaskell, S.J.

    1981-07-01

    Highly specific methods are described for determining testosterone in plasma or serum from men. Extract fractions obtained by selective isolation procedures are converted to tert-butyldimethylsilyl (TBDMS) oximes/TBDMS ethers or methyl oximes/TBDMS ethers and analyzed by gas chromatography/mass spectrometry in the high-resolution selected-ion monitoring or metastable peak-monitoring modes. (2H3)Testosterone and unlabeled 17-epitestosterone are used as the respective internal standards. When we applied the two procedures to analysis of samples of pooled plasma and serum used for external quality assessment of routine assays, the results agreed well. Interlaboratory values for mean concentrations obtained by routine immunoassays (y) consistently exceeded values obtained by our technique (x), although the values closely correlated (r . 0.997; y . 1.008x + 0.564 nmol/L).

  15. Direct chemical-analysis of uv laser-ablation products of organic polymers by using selective ion monitoring mode in gas-chromatography mass-spectrometry

    USGS Publications Warehouse

    Cho, Yirang; Lee, H.W.; Fountain, S.T.; Lubman, D.M.

    1994-01-01

    Trace quantities of laser ablated organic polymers were analyzed by using commercial capillary column gas chromatography/mass spectrometry; the instrument was modified so that the laser ablation products could be introduced into the capillary column directly and the constituents of each peak in the chromatogram were identified by using a mass spectrometer. The present study takes advantage of the selective ion monitoring mode for significantly improving the sensitivity of the mass spectrometer as a detector, which is critical in analyzing the trace quantities and confirming the presence or absence of the species of interest in laser ablated polymers. The initial composition of the laser ablated polymers was obtained by using an electron impact reflectron time-of-flight mass spectrometer and the possible structure of the fragments observed in the spectra was proposed based on the structure of the polymers.

  16. Analysis of Disperse Dyes Using Liquid Chromatography/Linear Ion Trap Mass Spectrometry (LC/LIT-MS(n)) and Database Construction.

    PubMed

    Kato, Takao; Ikeue, Takahisa; Suzuki, Yasuhiro; Handa, Makoto

    2016-01-01

    Liquid chromatography/linear ion trap mass spectrometry (LC/LIT-MS(n)) was used to construct a database of disperse dyes. Fifty-three standard dyes were subjected to LC/LIT-MS(n) and characterized based on their mass spectra (MS, MS(2), and MS(3)), values of λmax (maximum absorption wavelength in the UV-visible spectrum), and retention times. The results demonstrate that it is possible to reliably identify coexisting dyes that cannot be separated by LC or detected by diode array detection due to their low molecular absorption coefficients. In addition, the by-products included in the standard dyes were found to provide important information for the identification and discrimination of dyestuffs synthesized using different processes. The confirmation of the effectiveness of LC/LIT-MS(n) analysis in detecting small amounts of disperse dyes in this study shows its potential for use in the discrimination of dyed fibers obtained at crime scenes. PMID:26860557

  17. Identification of 3',4'-Dimethoxy Flavonol-3-β-d-Glucopyranoside Metabolites in Rats by Liquid Chromatography-Electrospray Ionization Ion Trap Mass Spectrometry.

    PubMed

    Zhu, Yuan; Wen, Jun; Cao, Yuqing; Jiang, Yuanying; Huang, Jinghua; Fan, Guorong; Lou, Yuefen

    2016-01-01

    A method using liquid chromatography-electrospray ionization ion trap mass spectrometry was established for the identification of metabolites in feces, urine and bile in rats after oral administration of 3',4'-dimethoxy flavonol-3-β-d-glucopyranoside (abbreviated DF3G). Seven metabolites in rat feces, urine and bile were firstly identified on the basis of their MS fragmentation behaviors. Three metabolites were identified in the feces, 6 in the urine and 2 in the bile, which suggested that demethylation, deglycosylation and deglycosylation followed by glucuronide conjugation were the major metabolic pathways for DF3G in vivo. Hydrolyzation might be the first step in the absorption and metabolism of DF3G. The possible metabolic pathway was proposed for the first time. The established method was simple, reliable and sensitive, revealing that it could be used to rapidly screen and identify the structures of metabolites of DF3G to better understand its metabolism in vivo. PMID:27070571

  18. Determination of cis-thymine glycol in DNA by gas chromatography-mass spectrometry with selected ion recording and multiple reaction monitoring.

    PubMed

    Farooq, S; Bailey, E; Farmer, P B; Jukes, R; Lamb, J H; Hernández, H; Sram, R; Topinka, J

    1997-11-21

    A novel method for the determination of cis-thymine glycol in DNA has been developed, using gas chromatography-mass spectrometry with selected ion recording or multiple reaction monitoring. The procedure involves acidic hydrolysis of DNA in the presence of the internal standard cis-[2H3]thymine glycol, followed by derivatisation with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. The method was validated on DNA that had been oxidatively modified in vitro by radiation treatment, and was then applied to determine cis-thymine glycol in human placental DNA. Background levels of 5.45+/-2.98 ng cis-thymine glycol/mg DNA were observed in the human samples. PMID:9449555

  19. Pesticide residue analysis of a dietary ingredient by gas chromatography/selected-ion monitoring mass spectrometry using neutral alumina solid-phase extraction cleanup.

    PubMed

    Jeong, Mijeong Lee; Zahn, Michael; Trinh, Thao; Brooke, Fay A; Ma, Wenwen

    2008-01-01

    A sample cleanup procedure has been developed to remove coextractives that interfere with pesticide residue analysis of a dietary ingredient (Product B), an extract consisting of Scutellaria baicalensis and Acacia catechu. Samples were extracted using 1% acetic acid in acetonitrile, followed by solid-phase extraction and analysis by capillary gas chromatography with mass spectrometry in the selective-ion monitoring mode. Neutral alumina (alumina N) was found to be the most effective sorbent to remove coextractives from Product B; other materials that were tested but failed to remove interference were graphitized carbon black/primary-secondary amine (PSA), octadecylsilane (C18), Florisil, Oasis MCX, and strong anion exchange-PSA. The method was specifically developed for Product B, which was spiked with 41 organochlorine and organophosphorus pesticides, and resulted in the recovery of 80 to 120% at U.S. Pharmacopeia limits (0.06 to 4 microg/g) for the majority of the pesticides. PMID:18567310

  20. Analysis of the in vitro metabolites of diferuloylmethane (curcumin) by liquid chromatography--tandem mass spectrometry on a hybrid quadrupole linear ion trap system: newly identified metabolites.

    PubMed

    Tamvakopoulos, Constantin; Sofianos, Zacharias D; Garbis, Spiros D; Pantazis, Panayotis

    2007-01-01

    In this study, we have described a novel approach for determining the metabolic scheme of diferuloylmethane (curcumin) in mouse and human liver microsomal preparations using a hybrid quadrupole linear ion trap mass spectrometer coupled with liquid chromatography for the detection of new metabolites. Application of various acquisition modes allowed targeted searches for metabolites with high sensitivity and selectivity using information of the mass spectral fragmentation properties of curcumin. Structural assignments for metabolites previously reported in the literature were made with confidence using the described approach. In addition, we identified curcumin metabolites that had not previously been reported, such as curcumin bisglucuronide and O-demethylated derivatives. The major pathways of curcumin metabolism in vitro have been summarized. Finally, very similar metabolic pathways of curcumin were observed in human and mouse microsomes. PMID:17479544