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1

Distribution analysis of cellulose acetate phthalate by ion-exclusion-moderated size exclusion chromatography  

Microsoft Academic Search

Ion-exclusion is the electrostatic repulsive interaction between a charged polymer and charges of the same sign on the surface of a column packing. Controlled ion-exclusion allows compensation of hydrophobic adsorption in size exclusion chromatography of negatively charged cellulose acetate phthalate (CAP) polymers in acetone\\/water\\/LiCl (80\\/20) as a mobile phase. Properly selected low-ionic-strength conditions provide correct separation in size-exclusion mode also

B Porsch; I Hillang; A Karlsson; L.-O Sundelöf

2002-01-01

2

Exclusion Chromatography  

NSDL National Science Digital Library

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

Kimball, John W.

2011-05-03

3

Ion-Exclusion Chromatography for Analyzing Organics in Water  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

4

Separation of Some Weak-Acid Anions by Ion-Exclusion Chromatography.  

National Technical Information Service (NTIS)

The separation of citrate, lactate, fluoride, borate, carbonate, and cyanide from strong-acid anions by ion-exclusion chromatography was investigated. Dilute hydrochloric acid was used as the eluent. Conductimetric measurement of the separate species was ...

C. Pohlandt

1981-01-01

5

Vacancy ion-exclusion chromatography of haloacetic acids on a weakly acidic cation-exchange resin  

Microsoft Academic Search

A new and simple approach is described for the determination of the haloacetic acids (such as mono-, di- and trichloroacetic acids) usually found in drinking water as chlorination by-products after disinfection processes and acetic acid. The new approach, termed vacancy ion-exclusion chromatography, is based on an ion-exclusion mechanism but using the sample solution as the mobile phase, pure water as

Murad I. H. Helaleh; Kazuhiko Tanaka; Masanobu Mori; Qun Xu; Hiroshi Taoda; Ming-Yu Ding; Wenzhi Hu; Kiyoshi Hasebe; Paul R. Haddad

2003-01-01

6

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

PubMed

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

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

2004-06-11

7

Vacancy ion-exclusion chromatography of haloacetic acids on a weakly acidic cation-exchange resin.  

PubMed

A new and simple approach is described for the determination of the haloacetic acids (such as mono-, di- and trichloroacetic acids) usually found in drinking water as chlorination by-products after disinfection processes and acetic acid. The new approach, termed vacancy ion-exclusion chromatography, is based on an ion-exclusion mechanism but using the sample solution as the mobile phase, pure water as the injected sample, and a weakly acidic cation-exchange resin column (TSKgel OApak-A) as the stationary phase. The addition of sulfuric acid to the mobile phase results in highly sensitive conductivity detection with sharp and well-shaped peaks, leading to excellent and efficient separations. The elution order was sulfuric acid, dichloroacetic acid, monochloroacetic acid, trichloroacetic acid, and acetic acid. The separation of these acids depends on their pKa values. Acids with lower pKa values were eluted earlier than those with higher pKa, except for trichloroacetic acid due to a hydrophobic-adsorption effect occurring as a side-effect of vacancy ion-exclusion chromatography. The detection limits of these acids in the present study with conductivity detection were 3.4 microM for monochloroacetic acid, 0.86 microM for dichloroacetic acid and 0.15 microM for trichloroacetic acid. PMID:12830885

Helaleh, Murad I H; Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Taoda, Hiroshi; Ding, Ming-Yu; Hu, Wenzhi; Hasebe, Kiyoshi; Haddad, Paul R

2003-05-16

8

Recovery of ionic liquid and sugars from hydrolyzed biomass using ion exclusion simulated moving bed chromatography.  

PubMed

Efficient recovery of ionic liquid (IL) from aqueous mixture of ILs and sugars (which derived from enzymatic or chemical catalyzed hydrolysis of ILs-pretreated biomass) is a major drawback for commercialization of biofuel and platform chemicals production from biomass utilized ILs as pretreatment solvent. In this study, simulated moving bed (SMB) chromatography equipped with ion exclusion column (containing [Emim]+ cation) was investigated to separate sugars (glucose and xylose) which are the main products from biomass hydrolysate and 1-ethyl-3-methylimidazolium acetate (EmimAc) which is the ILs used for biomass pretreatment. A four-zone SMB system with a configuration of 2-2-2-2 (2 ion exclusion columns in each zone) was used to recover glucose, xylose and EmimAc from their aqueous mixture with yield of 71.38, 99.37 and 98.92%, respectively. Moreover, the optimization of SMB zone configuration by simulation results in a complete recovery of ILs. This result indicates that for the first time, ion exclusion SMB chromatography could be used for complete recovery of ILs from aqueous sugar mixture. PMID:22265172

Mai, Ngoc Lan; Nguyen, Nam Trung; Kim, Jin-Il; Park, Hyuk-Min; Lee, Sung-Kyun; Koo, Yoon-Mo

2012-03-01

9

[Determination of maleic hydrazide in vegetables by high performance ion-exclusion chromatography].  

PubMed

A new method was developed for the determination of maleic hydrazide (MH) in potatoes, onions and garlics by high performance ion-exclusion chromatography (HPIEC). The sample was extracted with acidic methanol, and then analyzed by HPIEC. The analytical column was IonPac ICE-AS1 (250 mm x 9 mm) and a mixture of 3 mmol/L formic acid water solution-acetonitrile (70: 30, v/v) was used as the eluent at a flow rate of 0.8 mL/min. The detection was performed at 205 nm by an Ultimate 3000 VWD. The quantitative analysis of external standard calibration curves was used. The linear range of the method for MH was 0.006 - 1.0 mg/L (r = 0.999 9). The average recoveries were 91% - 103% with relative standard deviations (RSDs) less than 3%. The detection limit was 0.002 mg/L for MH. The method is simple, effective, precise, sensitive, reproducible and selective. It can be used to determine the residue of MH in potatoes, onions and garlics. PMID:21046793

Pan, Guangwen; Zhao, Zengyun; Hu, Zhongyang; Ye, Mingli

2010-07-01

10

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

SciTech Connect

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

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

1994-10-01

11

Vacancy ion-exclusion/adsorption chromatography of aliphatic amines on a polymethacrylate-based weakly basic anion-exchange column.  

PubMed

Vacancy ion-exclusion/adsorption chromatography has been applied to investigate the separation behavior of five aliphatic amines (ethylamine, propylamine, butylamine, pentylamine and hexylamine) on a polymethacrylate-based weakly basic anion-exchange column (Tosoh TSKgel DEAE-5PW). This system is consisted of analytes as a mobile phase and water as an injected sample. In the vacancy ion-exclusion/adsorption chromatography, the elution order was as follows: ethylamine < propylamine < butylamine < pentylamine < hexylamine, depending on their hydrophobicity. The retention times of the amines were decreased with decreasing their concentrations in the mobile phase. The retention times and resolutions of the amines were increased by adding a basic compound (e.g., lithium hydroxide or heptylamine) and by increasing the pH of mobile phase (pH > 11). This was because the dissociations of amine samples in the mobile phase were suppressed and thus the hydrophobic adsorption effects were enhanced. The linearity of calibration graphs could be obtained from the peak areas of the amine samples injected to the 0.05, 0.5 and 5 mM of amine mobile phase at pH 11 by heptylamine. The detection limits of aliphatic amines as injected samples were around 1 microM for five aliphatic amines at three different amine mobile phases. From these results, the retention behaviors of aliphatic amines on vacancy ion-exclusion/adsorption chromatography were concluded to be governed by the hydrophobic adsorption effect. PMID:15250414

Mori, Masanobu; Helaleh, Murad I H; Xu, Qun; Hu, Wenzhi; Ikedo, Mikaru; Ding, Ming-Yu; Taoda, Hiroshi; Tanaka, Kazuhiko

2004-06-11

12

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  

Microsoft Academic Search

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

Tetsuya Nakazato; Hiroaki Tao; Tadashi Taniguchi; Kenji Isshiki

2002-01-01

13

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

Microsoft Academic Search

The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1–C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic

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

2003-01-01

14

Determination of acrylamide in starch-based foods by ion-exclusion liquid chromatography  

Microsoft Academic Search

A simple and rapid method using liquid chromatography coupled with diode array detection (LC–DAD) was developed for the determination of acrylamide in starch-based foods. The method entails extraction of acrylamide with 75% (v\\/v) methanol in water, concentration, and cleanup with an Oasis HLB solid-phase extraction (SPE) cartridge. The chromatographic separations were performed on an HC-75H+ column with 5mM sulfuric acid

Zhiming Geng; Rong Jiang; Ming Chen

2008-01-01

15

High-performance ion-exclusion\\/cation-exchange chromatography of anions and cations in acid rain waters on a weakly acidic cation-exchange resin  

Microsoft Academic Search

A new method for the simultaneous determination of anions (sulfate, nitrate, and chloride) and cations (sodium, ammonium, potassium, magnesium, and calcium) in acid rain waters was investigated using high-performance ion-exclusion\\/cation-exchange chromatography with conductimetric detection on a separation column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the hydrogen-form and an eluent comprising 1.5 mM sulfosalicylic acid–6 mM 18-crown-6 at

Kazuhiko Tanaka; Kazutoku Ohta; Paul R Haddad; James S Fritz; Akiyashi Miyanaga; Wenzhi Hu; Kiyashi Hasebe; Kwang-Pill Lee; Corrado Sarzanini

2001-01-01

16

Simultaneous ion-exclusion\\/cation-exchange chromatography of anions and cations in acid rain waters on a weakly acidic cation-exchange resin by elution with sulfosalicylic acid  

Microsoft Academic Search

A simple, selective, and sensitive method for the simultaneous determination of anions (sulfate, nitrate, and chloride) and cations (sodium, ammonium, potassium, magnesium, and calcium) in acid rain waters was developed using ion-exclusion\\/cation-exchange chromatography with conductimetric detection. A weakly acidic cation-exchange resin column (Tosho TSKgel OA-PAK-A) and a sulfosalicylic acid–methanol–water eluent was used. With a mobile phase comprising 1.25 mM sulfosalicylic

Kazuhiko Tanaka; Kazutoku Ohta; Paul R Haddad; James S Fritz; Akiyoshi Miyanaga; Wenzhi Hu; Kiyoshi Hasebe

2000-01-01

17

Ion Exchange Chromatography  

NSDL National Science Digital Library

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

2011-05-23

18

Vacancy ion-exclusion chromatography of inorganic acids on a weakly acidic cation-exchange resin column.  

PubMed

Vacancy ion-exclusion chromatography (VIEC) for inorganic acids such as H(2)SO(4), HCl, H(3)PO(4), HNO(3), HI and HF is tested on a polymethacrylate-based weakly acidic cation-exchange resin column in the H(+)-form. That is, mixture of inorganic acids in the mobile phase is adsorbed to the resin phase passing through the separation column, and each vacant peak induced by injecting water is determined. Retention times are dependent on the degrees of retention for each analyte in the resin phase. In VIEC, well-shaped peaks of inorganic acids are produced, leading to efficient separations. However, retention behaviors of inorganic acids were strongly affected by the concentrations of the acids in the mobile phase. Sulfosalicylic acid was mixed with inorganic acids in the mobile phase prior to the introduction of a separation column in order to obtain the well-resolutions in the lower concentrations of the acids. By using this method, the separations of inorganic acids could be achieved in the range of 0.01-1 mM, and the linear ranges could be extended over two-orders of magnitude. This is considered since the protonated carboxylic groups fixed on the resin phase were increased with increasing the acid concentrations in the mobile phase, and the penetration effects for the acids to the resin phase were thus enhanced. The detection limits (S/N=3) were below 1.0 microM for all analyte acids. Precision values for retention times were below 0.32% and for peak area were below 0.91%. PMID:16472541

Mori, Masanobu; Itabashi, Hideyuki; Helaleh, Murad I H; Kaczmarski, Krzysztof; G?ód, Bronis?aw; Kowalska, Teresa; Xu, Qun; Ikedo, Mikaru; Hu, Wenzhi; Tanaka, Kazuhiko

2006-06-16

19

Determination of acrylamide in drinking water by large-volume direct injection and ion-exclusion chromatography–mass spectrometry  

Microsoft Academic Search

Acrylamide, a known neurotoxin and putative human carcinogen, has been included among the substances to be monitored in drinking water according to the European Union Directive 98\\/83 on potable water. This paper reports a new method based on the combination of ion-exclusion chromatographic separation and MS detection. Samples of drinking water have been directly injected in the microbore ICE-AS1 column

S Cavalli; S Polesello; G Saccani

2004-01-01

20

Ion Chromatography: An Account of Its Conception and Early Development  

ERIC Educational Resources Information Center

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

Small, Hamish

2004-01-01

21

Determination of acrylamide in drinking water by large-volume direct injection and ion-exclusion chromatography-mass spectrometry.  

PubMed

Acrylamide, a known neurotoxin and putative human carcinogen, has been included among the substances to be monitored in drinking water according to the European Union Directive 98/83 on potable water. This paper reports a new method based on the combination of ion-exclusion chromatographic separation and MS detection. Samples of drinking water have been directly injected in the microbore ICE-AS1 column and detected in the selected-ion monitoring mode by a single quadrupole system with electrospray ionization. Chromatographic conditions, such as eluent composition and flow rate, have been optimized by a central composite design experiment. Statistical analysis of data showed that the amount of acetonitrile fraction in the eluent mixture, composed by acetonitrile and formic acid solution, is the variable that most influences retention of the acrylamide peak. After optimization of MS detection parameters, this method has been validated for spiked drinking water samples. The effect of large-volume injection (up to 500 microl) has been also explored. Linearity was evaluated from 0.5 to 5 microg l(-1). Repeatability, expressed as R.S.D., was 16 and 12% at 0.5 and 1 microg l(-1) respectively. The limit of detection was 0.20 ppb with 500 microl injection volume. PMID:15250418

Cavalli, S; Polesello, S; Saccani, G

2004-06-11

22

Characterization of loaded liposomes by size exclusion chromatography.  

PubMed

This review focuses on the use of conventional (SEC) and high performance (HPSEC) size exclusion chromatography for the analysis of liposomes. The suitability of both techniques is examined regarding the field of liposome applications. The potentiality of conventional SEC is strongly improved by using a HPLC system associated to gel columns with a size selectivity range allowing liposome characterization in addition to particle fractionation. Practical aspects of size exclusion chromatography are described and a methodology based on HPSEC coupled to multidetection modes for on-line analysis of liposomes via label or substance encapsulation is presented. Examples of conventional SEC and HPSEC applications are described which concern polydispersity, size and encapsulation stability, bilayer permeabilization, liposome formation and reconstitution, incorporation of amphiphilic molecules. Size exclusion chromatography is a simple and powerful technique for investigation of encapsulation, insertion/interaction of substances from small solutes (ions, surfactants, drugs, etc.) up to large molecules (proteins, peptides and nucleic acids) in liposomes. PMID:12834977

Grabielle-Madelmont, Cécile; Lesieur, Sylviane; Ollivon, Michel

2003-06-30

23

Liposome retention in size exclusion chromatography  

PubMed Central

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

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

2005-01-01

24

Ion-exclusion chromatography with the direct UV detection of non-absorbing inorganic cations using an anion-exchange conversion column in the iodide-form.  

PubMed

An ion-exclusion chromatographic method for the direct UV detection of non-absorbing inorganic cations such as sodium (Na(+)), ammonium (NH(4)(+)) and hydrazine (N(2)H(5)(+)) ions was developed by connecting an anion-exchange column in the I(-)-form after the separation column. For example, NH(4)(+) is converted to a UV-absorbing molecule, NH(4)I, by the anion-exchange column in the I(-)-form after the ion-exclusion separation on anion-exchange column in the OH(-)-form with water eluent. As a result, the direct UV detection of Na(+), NH(4)(+) and N(2)H(5)(+) could be successfully obtained as well as the well-resolved separation. The calibration graphs of the analyte cations detected with UV at 230nm were linear in the range of 0.001-5.0mM. The detection limits at S/N=3 of the cations were below 0.1muM. This method was applied to real water analysis, the determination of NH(4)(+) in river and rain waters, or that of N(2)H(5)(+) in boiler water, with the satisfactory results. This could be applied also to low- or non-absorbing anions such as fluoride or hydrogencarbonate ions by the combination of a weakly acidic cation-exchange resin in the H(+)-form as the separation column and the anion-exchange conversion column. PMID:18970747

Mori, Masanobu; Itabashi, Hideyuki; Ikedo, Mikaru; Tanaka, Kazuhiko

2006-08-15

25

Size-exclusion chromatography of perfluorosulfonated ionomers.  

PubMed

A size-exclusion chromatography (SEC) method in N,N-dimethylformamide containing 0.1 M LiNO(3) is shown to be suitable for the determination of molar mass distributions of three classes of perfluorosulfonated ionomers, including Nafion(®). Autoclaving sample preparation is optimized to prepare molecular solutions free of aggregates, and a solvent exchange method concentrates the autoclaved samples to enable the use of molar-mass-sensitive detection. Calibration curves obtained from light scattering and viscometry detection suggest minor variation in the specific refractive index increment across the molecular size distributions, which introduces inaccuracies in the calculation of local absolute molar masses and intrinsic viscosities. Conformation plots that combine apparent molar masses from light scattering detection with apparent intrinsic viscosities from viscometry detection partially compensate for the variations in refractive index increment. The conformation plots are consistent with compact polymer conformations, and they provide Mark-Houwink-Sakurada constants that can be used to calculate molar mass distributions without molar-mass-sensitive detection. Unperturbed dimensions and characteristic ratios calculated from viscosity-molar mass relationships indicate unusually free rotation of the perfluoroalkane backbones and may suggest limitations to applying two-parameter excluded volume theories for these ionomers. PMID:21782181

Mourey, T H; Slater, L A; Galipo, R C; Koestner, R J

2011-08-26

26

Using Ion Exchange Chromatography to Separate Proteins  

NSDL National Science Digital Library

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

Daugherty, Ellyn A.; Exchange, Access E.

27

Using Ion Exchange Chromatography to Separate Proteins  

NSDL National Science Digital Library

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

Daugherty, Ellyn A.

2010-02-02

28

Influence of acidic eluent for retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography on a weakly acidic cation-exchange resin in the H+ -form.  

PubMed

Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) (first dissociation constant) of acid in eluent. The retention behaviors of anions and cations were related to that of elution dip induced after eluting acid to separation column and injecting analyte sample. These results were largely dependent on the natures of acid as eluent. Through this study, succinic acid as the eluent was suitable for simultaneous separation of strong acid anions (SO(4)(2-), Cl(-), NO(3)(-) and I(-)), weak acid anions (F(-), HCOO(-) and CH(3)COO(-)), and cations (Na(+), K(+), NH(4)(+), Mg(2+) and Ca(2+)). The separation was achieved in 20 min under the optimum eluent condition, 20 mM succinic acid/2 mM 18-crown-6. Detection limits at S/N=3 ranged from 0.10 to 0.51 microM for strong acid anions, 0.20 to 5.04 microM for weak acid anions and 0.75 to 1.72 microM for cations. The relative standard deviations of peak areas in the repeated chromatographic runs (n=10) were in the range of 1.1-2.9% for anions and 1.8-4.5% for cations. This method was successfully applied to hot spring water containing strong acid anions, weak acid anions and cations, with satisfactory results. PMID:16546200

Mori, Masanobu; Tanaka, Kazuhiko; Satori, Tatsuya; Ikedo, Mikaru; Hu, Wenzhi; Itabashi, Hideyuki

2006-06-16

29

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

PubMed

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

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

2011-01-01

30

Two-dimensional high-performance liquid chromatography using monodisperse polymer beads containing segregated chemistries prepared by pore size specific functionalization. Single-column combinations of size exclusion or ion exchange with reversed-phase chromatography.  

PubMed

Separation media for the complete separation of complex samples that require a combination of size exclusion or ion-exchange with reversed-phase chromatographic modes in a single column have been prepared from size monodisperse 10 microns poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads using a pore size specific functionalization process. To achieve the first combination of chromatographic modes, the large pores of the beads were selectively hydrolyzed to diols using aqueous poly(styrenesulfonic acid), while highly hydrophobic octadecyl groups were introduced into the small pores by reaction of the remaining epoxide groups with octadecylamine. These beads provide excellent protein recoveries and may be used for the direct injection separation of samples containing both hydrophilic proteins and hydrophobic drugs. Beads containing diethylamino groups in the large pores and octadecyl functionalities in the small pores were also prepared by size-selective modification. A plot of log k' against ionic strength of the mobile phase for these beads shows the absence of hydrophobic interactions and documents the clean ion-exchange mechanism of protein separation. Examination of the small pores in both types of separation media confirmed that their hydrophobicity was sufficient to allow the separations of small molecules in reversed-phase mode. Column packed with these dual-chemistry beads exhibited high efficiencies and were used successfully for the separations of proteins and alkylbenzenes or drugs. PMID:7847631

Smigol, V; Svec, F; Fréchet, J M

1994-12-01

31

Size exclusion-high-performance liquid chromatography (SEC-HPLC).  

PubMed

The size exclusion-high-performance liquid chromatography is a high-throughput analytical method, through isocratic condition, that allows to determine and quantify the level of aggregates and fragments of purified antibodies. Here, we describe the preparation of the samples, chromatographic conditions to be used (buffer preparation, quantity injected, flow rate, run time, column suitability, etc.), validity of the analysis, and integration of the chromatogram in order to calculate the proportion of the different components. PMID:24515486

Schrag, Delphine; Corbier, Marie; Raimondi, Sylvain

2014-01-01

32

High-speed ion-exclusion chromatography of dissolved carbon dioxide on a small weakly acidic cation-exchange resin column with ion-exchange enhancement columns of conductivity detection.  

PubMed

The high-speed ion-exclusion chromatographic determination of dissolved carbon dioxide, i.e., carbonic acid, hydrogencarbonate or carbonate, with conductivity detection was obtained using a small column packed with a weakly acidic cation-exchange resin in the H+-form (40 mm long x 4.6 mm i.d., 3 microm-particle and 0.1 meq./ml-capacity). Two different ion-exchange resin columns, which were a strongly acidic cation-exchange resin in the K+-form and a strongly basic anion-exchange resin in the OH- -form, were connected after the separation column. The sequence of columns could convert dissolved carbon dioxide to KOH having high conductivity response. The enhancement effect for dissolved carbon dioxide could retain even on the vast chromatographic runs, by using the enhancement columns with high ion-exchange capacity above 1.0 meq./ml. The retention time was in 60 s at flow-rate of 1.2 ml/min. The calibration graph of dissolved carbon dioxide estimated as H2CO3- was linear in the range of 0.005-10 mM. The detection limit at signal to noise of 3 was 0.15 microM as H2CO3-. This method was applicable to several rainwater and tap water samples. PMID:16199234

Mori, Masanobu; Ikedo, Mikaru; Hu, Wenzhi; Helaleh, Murad I H; Xu, Qun; Itabashi, Hideyuki; Tanaka, Kazuhiko

2005-10-28

33

Selectivity in preparative separations of inorganic electrolytes by size-exclusion chromatography on hypercrosslinked polystyrene and microporous carbons  

Microsoft Academic Search

Preparative-scale separation of concentrated solutions of simplest mineral electrolytes by size-exclusion chromatography was performed on three samples of commercially available microporous hypercrosslinked polystyrene sorbents “Macronet Hypersol” and two experimental samples of activated carbons. Selectivity of separation of a pair of electrolytes was found to be determined by the largest ions in each pair. Fortunately, selectivity rises at higher concentrations of

V. A. Davankov; M. P. Tsyurupa; N. N. Alexienko

2005-01-01

34

Ion Chromatography Analysis of Dibutyl Phosphoric Acid.  

National Technical Information Service (NTIS)

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) concentra...

R. J. Ray

1998-01-01

35

Application of artificial intelligence to ion chromatography  

NASA Astrophysics Data System (ADS)

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

Ramadan, Ziad

1999-10-01

36

The History of Ion Chromatography: The Engineering Perspective  

ERIC Educational Resources Information Center

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

Evans, Barton

2004-01-01

37

Optimization Strategies in Ion Chromatography  

Microsoft Academic Search

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

Tomislav Bolan?a

2007-01-01

38

Size-exclusion chromatography system for macromolecular interaction analysis  

DOEpatents

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

Stevens, Fred J. (Downers Grove, IL)

1988-01-01

39

Separation of lithium ions by chromatography  

SciTech Connect

Trioctylphosphine oxide (TOPO) forms an adduct with lithium dibenzoylmethane (DBM). The chelate is readily extractable by nonaqueous solvents, and this is the basis for the chromatographic separation of lithium from other alkali ions. A liquid chromatography column with 0.1 M DBM - 0.1 M TOPO in dodecane as the stationary phase was used. Lithium ions were retrained on the column while the remaining alkali metal ions were eluted with ammonium hydroxide. Lithium was eluted with 0.6 N hydrochloric acid. The structure of the extracted lithium species was determined by extraction equilibria studies and by the method of continuous variations.

Lee, D.A.

1983-11-12

40

Peak distortion effects in analytical ion chromatography.  

PubMed

The elution profile of chromatographic peaks provides fundamental understanding of the processes that occur in the mobile phase and the stationary phase. Major advances have been made in the column chemistry and suppressor technology in ion chromatography (IC) to handle a variety of sample matrices and ions. However, if the samples contain high concentrations of matrix ions, the overloaded peak elution profile is distorted. Consequently, the trace peaks shift their positions in the chromatogram in a manner that depends on the peak shape of the overloading analyte. In this work, the peak shapes in IC are examined from a fundamental perspective. Three commercial IC columns AS16, AS18, and AS23 were studied with borate, hydroxide and carbonate as suppressible eluents. Monovalent ions (chloride, bromide, and nitrate) are used as model analytes under analytical (0.1 mM) to overload conditions (10-500 mM). Both peak fronting and tailing are observed. On the basis of competitive Langmuir isotherms, if the eluent anion is more strongly retained than the analyte ion on an ion exchanger, the analyte peak is fronting. If the eluent is more weakly retained on the stationary phase, the analyte peak always tails under overload conditions regardless of the stationary phase capacity. If the charge of the analyte and eluent anions are different (e.g., Br(-) vs CO3(2-)), the analyte peak shapes depend on the eluent concentration in a more complex pattern. It was shown that there are interesting similarities with peak distortions due to strongly retained mobile phase components in other modes of liquid chromatography. PMID:24328391

Wahab, M Farooq; Anderson, Jordan K; Abdelrady, Mohamed; Lucy, Charles A

2014-01-01

41

High Performance Liquid Chromatography–Size Exclusion Chromatography for Rapid Analysis of Total Polar Compounds in Used Frying Oils  

Microsoft Academic Search

Analysis of used frying oil samples by high performance liquid chromatography–size exclusion chromatography (HPLC–SEC or HPSEC)\\u000a was compared to AOCS Official Method Cd 20-91 (silica gel column chromatography) for the purpose of developing a rapid analysis\\u000a of total polar compounds (TPC). In a direct comparison of the two analytical methods using four different sets of used frying\\u000a oils (21 total

J. D. CaldwellB; B. S. Cooke; M. K. Greer

42

Ion Exchange Application of Overpressured Thin-Layer Chromatography  

Microsoft Academic Search

The application of overpressured thin-layer chromatography introduced into the field of ion exchange chromatography. The basic differences between overpressured thin-layer chromatography and classical thin-layer chromatography are discussed including the distinction between the separations performed on thin-layer plates containing silica gel and a mixture of ion exchanger material and silica gel. The basic increase of flow velocity of solvent front with

Huba Kalász; János Nagy

1981-01-01

43

Size-exclusion chromatography (SEC) of branched polymers and polysaccharides  

PubMed Central

Branched polymers are among the most important polymers, ranging from polyolefins to polysaccharides. Branching plays a key role in the chain dynamics. It is thus very important for application properties such as mechanical and adhesive properties and digestibility. It also plays a key role in viscous properties, and thus in the mechanism of the separation of these polymers in size-exclusion chromatography (SEC). Critically reviewing the literature, particularly on SEC of polyolefins, polyacrylates and starch, we discuss common pitfalls but also highlight some unexplored possibilities to characterize branched polymers. The presence of a few long-chain branches has been shown to lead to a poor separation in SEC, as evidenced by multiple-detection SEC or multidimensional liquid chromatography. The local dispersity can be large in that case, and the accuracy of molecular weight determination achieved by current methods is poor, although hydrodynamic volume distributions offer alternatives. In contrast, highly branched polymers do not suffer from this extensive incomplete separation in terms of molecular weight. Figure Representation of (a) a linear polymer chain and various branched polymer structures with (b) longchain branches (amylose-like), (c) short-chain branches (amylopectin-like), (d) both short-chain and long-chain branches (polyacrylate- or polyethylene-like).

Gaborieau, Marianne

2010-01-01

44

Chromatography  

MedlinePLUS

... high pressure liquid, or ion exchange chromatography. In general, chromatography takes advantage of the differences in the chemicals you want to separate, such as their size, electric charge, or ability to stick to (bind) to ...

45

An Empirical Formula From Ion Exchange Chromatography and Colorimetry.  

ERIC Educational Resources Information Center

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)

Johnson, Steven D.

1996-01-01

46

Analysis of fountain solutions for anionic components, including alkylbenzenesulfonates, carboxylates and polyphosphates, by a combination of ion-exchange and ion-exclusion chromatography and inductively coupled plasma atomic emission spectrometry  

Microsoft Academic Search

A method for the quantitative determination of the major anionic constituents of fountain solutions, typically mono-, di- and hydroxycarboxylates, alkylbenzenesulfonates, and inorganic anions, including orthophosphate and polyphosphates, is presented here for the first time. The analytical problems arising from extensive co-elution of many of these analytes on an ion-exchange column have been resolved through a combination of (i) careful selection

A. D Bewsher; D. A Polya; P. R Lythgoe; I. M Bruckshaw; D. A. C Manning

2001-01-01

47

Determination of polyacrylamide in soil waters by size exclusion chromatography.  

PubMed

Determination of polyacrylamide (PAM) concentration in soil waters is important in improving the efficiency of PAM application and understanding the environmental fate of applied PAM. In this study, concentrations of anionic PAM with high molecular weight in soil waters containing salts and dissolved organic matter (DOM) were determined quantitatively by size exclusion chromatography (SEC) with ultraviolet (UV) absorbance detection. Polyacrylamide was separated from interferential salts and DOM on a polymeric gel column eluted with an aqueous solution of 0.05 M KH2PO4 and then detected at a short UV wavelength of 195 nm. Analysis of PAM concentrations in soil sorption supernatants, soil leachates, and water samples from irrigation furrow streams showed that SEC is an effective approach for quantifying low concentrations (0-10 mg L(-1)) of PAM in waters containing soil DOM and salts. The method has a lower detection limit of 0.02 microg and a linear response range of 0.2 to 80 mg L(-1). Precision studies gave coefficients of variation of < 1.96% (n = 4) for > 10 mg L(-1) PAM and < 12% (n = 3) for 0.2 to 3 mg L(-1) PAM. PMID:14535339

Lu, Jianhang; Wu, Laosheng; Gan, Jianying

2003-01-01

48

Ion Chromatography Analysis of Dibutyl Phosphoric Acid  

SciTech Connect

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

Ray, R.J.

1998-12-04

49

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

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

Bierla, Katarzyna; Szpunar, Joanna; Lobinski, Ryszard

2008-08-29

50

Chromatographic NMR with size exclusion chromatography stationary phases  

NASA Astrophysics Data System (ADS)

Chromatographic NMR describes the use of stationary phases or solvent additives, such as polymers, to modify the diffusion properties of analyte molecules and thereby improve the observed resolution in the diffusion domain. This paper demonstrates similar ideas using size exclusion chromatographic media and characterises the changes in the observed diffusion coefficient using a series of polymer molecular weight reference standards of known polydispersity. The results are interpreted in terms of a simple description of the size exclusion phenomena.

Joyce, Rebecca E.; Day, Iain J.

2012-07-01

51

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

Microsoft Academic Search

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

M. Monteiro; C. Nerín; F. G. R. Reyes

1996-01-01

52

Immobilized Metal Ion Affinity Chromatography (IMAC) Chemistry and Bioseparation Applications  

Microsoft Academic Search

This review discusses the principles of immobilized metal ion affinity chromatography (IMAC) and its applications to protein separations. IMAC functions by binding the accessible electron-donating pendant groups of a protein - such as histidine, cysteine, and tryptophan - to a metal ion which is held by a chelating group covalently attached on a stationary support. A common chelating group is

Jon W. Wong; Robert L. Albright; Nien-Hwa L. Wang

1991-01-01

53

Determination of the permeability and porosity of anaerobic sludge granules by size exclusion chromatography  

Microsoft Academic Search

A new application of size-exclusion chromatography is described for assessment of the permeability and internal pore distribution of anaerobic sludge granules. The fractionation range and adsorption characteristics were investigated for a series of standard proteins and dextrans. To determine possible adsorption of solutes and stability of the sludges, the pH and salt concentration of the mobile phase were varied. Good

P. Arne Alphenaar; M. Cecilia Perez; Willem J. H. van Berkel; Gatze Lettinga

1992-01-01

54

Mathematical modeling and scale-up of size-exclusion chromatography  

Microsoft Academic Search

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

Zhiguo Li; Yesong Gu; Tingyue Gu

1998-01-01

55

Separation of Lithium Ions by Chromatography.  

National Technical Information Service (NTIS)

Trioctylphosphine oxide (TOPO) forms an adduct with lithium dibenzoylmethane (DBM). The chelate is readily extractable by nonaqueous solvents, and this is the basis for the chromatographic separation of lithium from other alkali ions. A liquid chromatogra...

D. A. Lee

1983-01-01

56

Mineral separation in a CELSS by ion-exchange chromatography  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

57

Forensic Identification of Inorganic Explosives by Ion Chromatography  

Microsoft Academic Search

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

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

2006-01-01

58

Determination of halogens in a petroleum product by ion chromatography  

SciTech Connect

A rapid, high-performance ion chromatography (HPIC) method with isocratic separation and the anion self-regenerating suppressor (in the chemical suppression mode, specifically for the determination of fluoride, chloride, bromide, and iodide in a petroleum product) is discussed. This is a proposed new method for a production laboratory within the Analytical Services Organization at the Oak Ridge Y-12 Plant.

Tucker, H.L.

1994-07-15

59

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...

60

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

NASA Astrophysics Data System (ADS)

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.

Zhang, Zhongqi

2012-08-01

61

Silica based click amino stationary phase for ion chromatography and hydrophilic interaction liquid chromatography.  

PubMed

A silica based amino stationary phase was prepared by immobilization of propargylamine on azide-silica via click chemistry. This readily prepared click amino stationary phase demonstrated good selectivity in separation of common inorganic anions under ion chromatography (IC) mode, and the triazole ring in combination with free amino group was observed to play a major role for separation of the anions examined. On the other hand, the stationary phase also showed good hydrophilic interaction liquid chromatography (HILIC) properties in the separation of polar compounds including nucleosides, organic acids and bases. The retention mechanism was found to match well the typical HILIC retention. PMID:22343922

Liu, Yajing; Du, Qing; Yang, Bingcheng; Zhang, Feifang; Chu, Changhu; Liang, Xinmiao

2012-04-01

62

Application of size-exclusion chromatography to polymers of ultra-high molar mass  

Microsoft Academic Search

This article describes the experimental conditions that should be applied to avoid molecular degradation in size-exclusion chromatography of polymers of ultra-high molar mass (weight-average molar mass Mw>5000 kg\\/mol). The applicability of the optimized experimental conditions is demonstrated using polystyrene as a model substance, but also by using polymers of biochemical and biophysical interest, such as polyethylene of ultra-high molar mass,

Nicolai Aust

2003-01-01

63

Effect of salt on purification of plasmid DNA using size-exclusion chromatography  

Microsoft Academic Search

In the present study, we compared the performances of size-exclusion chromatography for the purification of plasmid DNA when different concentrations (0.5M, 1M, 2M, respectively) of two types of salt (NaCl and (NH4)2SO4) are present in running buffers. Our experiment results displayed that it is not only the resolution of RNA but also those of supercoiled plasmid DNA and host's genomic

Liang-Zhu Li; Yong Liu; Mao-Sheng Sun; Yi-Ming Shao

2007-01-01

64

Use of Size-Exclusion High-Performance Liquid Chromatography for Wheat Quality Prediction in Ethiopia  

Microsoft Academic Search

Cereal Chem. 81(4):533-537 Wheat quality testing facilities in Ethiopia are limited. The aim of this study was to determine whether size-exclusion high-performance liquid chromatography (SE-HPLC) could be used in breeding programs for quality testing. Thirteen Ethiopian and two South African wheat cultivars were evaluated in two diverse environments for milling and dough char- acteristics. SE-HPLC was done on the same

M. T. Labuschagne; E. Koen; T. Dessalegn

2004-01-01

65

Molecular mass determination of polyamic acid ionic salt by size-exclusion chromatography.  

PubMed

A methodology was developed for the determination of molecular weight aveages of polyamic acid ionic salt (PAS) by size-exclusion chromatography (SEC). Polystyrene standards were used for calibration and THF-DMF 1:1 by volume containing 0.06 M LiBr and 0.06 M H3PO4 was used as the mobile phase. The proposed methodology was found to be reproducible. PMID:12456110

Krishnan, P Santhana Gopala; Veeramani, S; Vora, Rohit H; Chung, Tai-Shung; Uchimura, Shun-Ichiro; Sugitani, Hatsuo

2002-11-22

66

Ion-exchange chromatography of proteins near the isoelectric points  

Microsoft Academic Search

The retention and the resolution of ?-lactoglobulin A and B (LgA, LgB) were investigated with various ion-exchange chromatography media. The number of sites involved in the retention (adsorption) decreased as the mobile phase pH approached the isoelectric points pI (=5.1–5.2). However, even at pH 5.2 both LgA and LgB were retained on anion- and cation-exchange chromatography columns. The separation (resolution)

Shuichi Yamamoto; Takashi Ishihara

1999-01-01

67

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

PubMed

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

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

2012-06-01

68

Ion exchange-high-performance liquid chromatography (IEX-HPLC).  

PubMed

The ion exchange-high-performance liquid chromatography is a high-throughput analytical method that allows to determine the charge profile of purified antibodies. Here, we describe the preparation of the samples, chromatographic conditions to be used (buffer preparation, salt gradient, quantity injected, flow rate, run time, column suitability, etc.), validity of the analysis, and integration of the chromatogram in order to calculate the proportion of the different isoforms. PMID:24515485

Corbier, Marie; Schrag, Delphine; Raimondi, Sylvain

2014-01-01

69

Determination of some pesticides and intermediates by ion chromatography  

Microsoft Academic Search

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

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

2000-01-01

70

Mechanistic model of retention in protein ion-exchange chromatography  

Microsoft Academic Search

A mechanistic model is developed to describe the retention of proteins in ion-exchange chromatography, as a simplified version of a more elaborate colloidal model within which retention is related to protein and stationary-phase structural and functional parameters and eluent composition. The protein parameters are the size and net charge, while incorporation of stationary-phase properties, namely the surface charge density and

Charles M. Roth; Klaus K. Unger; Abraham M. Lenhoff

1996-01-01

71

Statistical quality control applied to ion chromatography calibrations  

Microsoft Academic Search

Multivariate statistical quality control principles, including control charting of calibration parameters and control samples, are applied to multilevel ion chromatography (IC) calibrations to determine instrument response stability and minimum calibration frequency. For phosphate species quantitated by suppressed-conductivity IC with NaOH gradient elution, ortho- and pyrophosphate exhibit stable responses over the 10-week course of the study, while tripolyphosphate shows a response

Frederick S Stover; Robert V Brill

1998-01-01

72

Characterization of copper-complexing ligands in seawater using immobilized copper(II)-ion affinity chromatography and electrospray ionization mass spectrometry  

Microsoft Academic Search

Electrochemical studies show that copper and other bioactive trace metals are associated almost exclusively with dissolved organic ligands in surface seawater. Some of these ligands may be released by photosynthetic marine organisms to control metal uptake. However, new analytical approaches are needed to determine the chemical composition and ecological significance of these compounds. We have combined immobilized metal-ion affinity chromatography

Andrew R. S Ross; Michael G Ikonomou; Kristin J Orians

2003-01-01

73

Determination of total chromium in phosphate rocks by ion chromatography.  

PubMed

Chromium(VI) is one of seven elements which is classified in the fertilizer industry as being harmful to plants and biological systems. Phosphate rocks represent the raw material for complex fertilizer production in the world. This paper investigates for the first time the determination of total chromium in phosphate rocks by ion chromatography. The developed analytical method involves the digestion of phosphate rocks with nitric acid followed by sample treatment of the resulting solution. The digestion solution obtained was treated with an oxidising agent (potassium peroxosulphate) to convert all chromium to the hexavalent state. The analytical method developed utilizes anion-exchange ion chromatography to achieve the separation and spectrophotometric post-column reaction for detection with diphenylcarbazide. The relative standard of deviation from analytical data comparison of six different phosphate rocks with atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry techniques, and cross-analysis data against an internationally certified phosphate rock standard were between 0.58 and 1.45%. Calibration curve between 0.2 and 0.9 microgram/ml was excellent, and the method has a detection limit for Cr(VI) of 0.05 ng. The developed method offers a fast, a reliable and an alternative procedure for the determination of total chromium in phosphate rock deposits by ion chromatography. PMID:10457474

al-Shawi, A W; Dahl, R

1999-07-30

74

Liquid Chromatography in 1982.  

ERIC Educational Resources Information Center

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

Freeman, David H.

1982-01-01

75

Adenovirus purification by two-column, size-exclusion, simulated countercurrent chromatography.  

PubMed

Adenovirus serotype 5 (Ad5) was successfully separated by size-exclusion chromatography (SEC) using a simple, yet efficient, two-column, quasi-continuous, simulated moving-bed process operated in an open-loop configuration. The operating cycle is divided into two identical half-cycles, each of them consisting of the following sequence of sub-steps: (i) elution of the upstream column and direction of the effluent of the downstream column to waste; (ii) elution of the upstream column and redirection of its effluent to waste while the downstream column is fed with the clarified bioreaction bulk and its effluent collected as purified product; (iii) operation of the system as in step (i) but collecting the effluent of the downstream column as product; (iv) elution of the upstream column and direction of its effluent to waste while the flow through the downstream column is temporarily halted. Clearance of impurities, namely DNA and host cell protein (HCP), were experimentally assessed. The pilot-scale run yielded a virus recovery of 86%, and a clearance of 90% and 89% for DNA and HCP, respectively, without any fine tunning of the predetermined operating parameters. These figures compare very favorably against single-column batch chromatography for the same volume of size-exclusion resin. However, and most importantly, the virus yield was increased from 57% for the batch system to 86% for the two-column SEC process because of internal recycling of the mixed fractions of contaminated Ad5, even though the two-column process was operated strictly in an open-loop configuration. And last, but not least, the productivity was increased by 6-fold with the two-column process. In conclusion, the main drawbacks of size-exclusion chromatography, namely low productivity and low product titer, were overcome to a considerable extent by an innovative two-column configuration that keeps the mixed fractions inside the system at all times. PMID:24813933

Nestola, Piergiuseppe; Silva, Ricardo J S; Peixoto, Cristina; Alves, Paula M; Carrondo, Manuel J T; Mota, José P B

2014-06-20

76

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

SciTech Connect

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

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

2006-07-01

77

Determination of UV stabilizers in PET bottles by high performance-size exclusion chromatography.  

PubMed

A Size Exclusion Chromatography-High Performance Liquid Chromatography (SECHPLC) method to determine antioxidants and UV stabilizers in PET bottles has been developed. In only a single run a synthetic mixture of the stabilizers was separated and quantified. The detection limit obtained for BHT, Tinuvin 326, Cyasorb UV 5411, and Tinuvin P was about 0.1 microgram/g and for Irgafos 168 it was 1.0 microgram. RSD values were lower than 3%. Tinuvin P was identified and quantified in PET bottle extracts. Olive oil, soybean oil and sunflower oil showed well defined separation from Tinuvin P at the same conditions of analysis. Cyclic dimers were identified in the PET extracts. PMID:8799719

Monteiro, M; Nerín, C; Reyes, F G

1996-07-01

78

Steroid receptor analysis by size-exclusion liquid chromatography: considerations for the clinical laboratory.  

PubMed

Steroid receptor activity can be more quickly estimated by size-exclusion chromatography than by conventional analysis on sucrose gradients, and profiles of receptor activity are better resolved. Here we discuss several factors affecting this form of analysis in clinical laboratories. The composition of the elution buffer influences steroid receptor elution and recovery: high ionic strength, neutral pH, and the presence of dimethylformamide are important. Of the TSK-SW (Beckman) size-exclusion chromatographic columns we considered, the TSK-G2000SW column appeared to be the most appropriate. "Reference" elution profiles are presented for several marker proteins and estrogen receptor forms generated under different sample-treatment conditions. In examining the sensitivity of receptor analyses by this method, we used fresh rodent preparations, a commercial receptor reference (Estrocept), and human tumor material obtained by needle biopsy. We also compared frozen and lyophilized receptor preparations with fresh ones. PMID:3978784

Pavlik, E J; Nelson, K; van Nagell, J R; Robinson, J C; Hanson, M B; Donaldson, E S; Flanigan, R C; Kenady, D E

1985-04-01

79

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

PubMed

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

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

2013-10-15

80

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

PubMed

Porous polymer spherical particles for column packings in nonaqueous size-exclusion chromatography (SEC) were prepared from 1,2-syndiotactic polybutadiene by suspension and evaporation method. The polymer microbeads obtained were crosslinked by radical reaction between 2-vinyl groups in polybutadiene with ultraviolet radiation, to render them insoluble. These microbeads have wider chromatographic separation width than polystyrene column packings. In addition, the polybutadiene microbeads did not show the excessive retention observed with commercial polystyrene columns for polycyclic aromatic compounds. Therefore, a close correlation between the elution volume and M, for polycyclic aromatic compounds was observed with polybutadiene microbeads columns. PMID:16035360

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

2005-08-01

81

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

Microsoft Academic Search

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

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

2009-01-01

82

Behavior of polysaccharide assemblies in field-flow fractionation and size-exclusion chromatography  

Microsoft Academic Search

Asymmetric flow field-flow fractionation (AsFlFFF) and high-performance size-exclusion chromatography (HPSEC) are techniques\\u000a for separating and characterizing macromolecules; until now the latter is more utilized for analyzing polysaccharides. The\\u000a demand for characterizing complex, high-molar-mass polysaccharides has raised interest in the use of AsFlFFF in analyzing\\u000a polymeric carbohydrates in addition to HPSEC. In this paper, we compare the behavior of arabinoxylan aggregates

Leena Pitkänen; Maija Tenkanen; Päivi Tuomainen

2011-01-01

83

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

PubMed

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-?-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

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

2014-08-01

84

What can in situ ion chromatography offer for Mars exploration?  

PubMed

Abstract The successes of the Mars exploration program have led to our unprecedented knowledge of the geological, mineralogical, and elemental composition of the martian surface. To date, however, only one mission, the Phoenix lander, has specifically set out to determine the soluble chemistry of the martian surface. The surprising results, including the detection of perchlorate, demonstrated both the importance of performing soluble ion measurements and the need for improved instrumentation to unambiguously identify all the species present. Ion chromatography (IC) is the state-of-the-art technique for soluble ion analysis on Earth and would therefore be the ideal instrument to send to Mars. A flight IC system must necessarily be small, lightweight, low-power, and have low eluent consumption. We demonstrate here a breadboard system that addresses these issues by using capillary IC at low flow rates with an optimized eluent generator and suppressor. A mix of 12 ions known or plausible for the martian soil, including 4 (oxy)chlorine species, has been separated at flow rates ranging from 1 to 10??L/min, requiring as little as 200?psi at 1.0??L/min. This allowed the use of pneumatic displacement pumping from a pressurized aluminum eluent reservoir and the elimination of the high-pressure pump entirely (the single heaviest and most energy-intensive component). All ions could be separated and detected effectively from 0.5 to 100??M, even when millimolar concentrations of perchlorate were present in the same mixtures. Key Words: Ion chromatography-Perchlorate (ClO4(-))-Mars soil-Oxychlorine species. Astrobiology 14, 577-588. PMID:24963874

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

2014-07-01

85

Advances in silver ion chromatography for the analysis of fatty acids and triacylglycerols-2001 to 2011.  

PubMed

An effort is made to critically present the achievements in silver ion chromatography during the last decade. Novelties in columns, mobile-phase compositions and detectors are described. Recent applications of silver ion chromatography in the analysis of fatty acids and triacylglycerols are presented while stressing novel analytical strategies or new objects. The tendencies in the application of the method in complementary ways with reversed-phase chromatography, chiral chromatography and, especially, mass detection are outlined. PMID:22975910

Momchilova, Svetlana M; Nikolova-Damyanova, Boryana M

2012-01-01

86

Ion chromatography in the manufacture of multilayer circuit boards  

NASA Astrophysics Data System (ADS)

Ion chromatography (IC) has proven useful in analyzing chemical solutions used in the manufacture of multilayer circuit boards. IC provides results on ions not expected in the production solutions. Thus, solution contamination and breakdown 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 mu in. 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 in. 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 total fluoroborate, tin, and lead. In addition, mobile phase ion chromatography (MPIC) is used to monitor the nonionic organic brighteners in the baths.

Smith, R. E.

1987-10-01

87

Ion chromatography in the manufacture of multilayer circuit boards  

NASA Astrophysics Data System (ADS)

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.

Smith, Robert E.

1990-01-01

88

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

PubMed

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

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

2011-11-01

89

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

PubMed Central

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

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

2012-01-01

90

Chromatography.  

ERIC Educational Resources Information Center

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

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

91

Functional speciation of metal-dissolved organic matter complexes by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry and deconvolution analysis  

Microsoft Academic Search

High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry (HP-SEC–ICP-MS), in combination with deconvolution analysis, has been used to obtain multielemental qualitative and quantitative information about the distributions of metal complexes with different forms of natural dissolved organic matter (DOM). High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry chromatograms only provide continuous distributions

Francisco Laborda; Sergio Ruiz-Beguería; Eduardo Bolea; Juan R. Castillo

2009-01-01

92

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

SciTech Connect

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.

Kawate,T.; Gouaux, E.

2006-01-01

93

Intercomparison of the measurements of oxalic acid in aerosols by gas chromatography and ion chromatography  

NASA Astrophysics Data System (ADS)

Oxalate, the anion of oxalic acid, is one of the most abundant measurable organic species in atmospheric aerosols. Traditionally, this bifunctional species has been measured by gas chromatography (GC) after derivatization to butyl ester and by ion chromatography (IC) without derivatization. However, there are few published comparisons of the two techniques. Here, we report the results of an intercomparison study for the measurement of oxalic acid in Arctic aerosols (<2.5 ?m, n = 82) collected in 1992 using GC and IC. The concentrations of oxalic acid by GC ranged from 6.5-59.1 ng m -3 (av. 26.0 ng m -3, median 26.2 ng m -3) whereas those by IC ranged from 6.6-52.1 ng m -3 (av. 26.6 ng m -3, median 25.4 ng m -3). They showed a good correlation ( r = 0.84) with a slope of 0.96. Thus, observations of oxalate obtained by GC employing dibutyl esters are almost equal to those by IC. Because the accuracy of oxalic acid by GC method largely depends on the method used, it is important to strictly examine the recovery in each study.

Kawamura, Kimitaka; Barrie, Leonard A.; Toom-Sauntry, Desiree

2010-12-01

94

Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography  

SciTech Connect

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

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

2010-06-15

95

Characterization and analysis of thermal denaturation of antibodies by size exclusion high-performance liquid chromatography with quadruple detection  

Microsoft Academic Search

Size exclusion chromatography (SEC) coupled with online light scattering, viscometry, refractometry, and UV–visible spectroscopy provides a very powerful tool for studying protein size, shape, and aggregation. This technique can be used to determine the molecular weight of the component peaks independent of the retention times in the SEC column and simultaneously measure the hydrodynamic radius and polydispersity of the protein.

Wanda K. Hartmann; Nirmala Saptharishi; Xiao Yi Yang; Gautam Mitra; Gopalan Soman

2004-01-01

96

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

97

Analysis of anions in hydrofluoro ethers by ion chromatography.  

PubMed

Hydrofluoro ethers (HFES) are considered to be an ideal cleaning solvent in applications like vapor degreasing and wet cleaning. It is also a good solvent replacement for CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), HFCs (hydrofluorocarbons) and chlorinated solvents because they have a short atmospheric lifetime and low global warming potential. Based upon their properties, hydrofluoro ethers are ideally suited for the demands of the electronics industry. However, the electronics industry requires these solvents to have high purity, especially in the area of residual anions. This paper will present information on an extraction methodology for the transfer of anions from the hydrofluoro ether to water. Then, an analytical method utilizing ion chromatography that is capable of detection of 10 anions (fluoride, acetate, formate, chloride, nitrite, bromide, nitrate, sulfate, oxalate, and phosphate) in the part per billion level will be demonstrated. PMID:15250412

Hulteen, John C; Schaible, Sandi M

2004-06-11

98

Thin-layer ion-exchange chromatography of proteins.  

PubMed

Thin-layer chromatography (TLC) is one of the simplest and most convenient techniques to separate small molecules. Of a variety of TLC separation modes, only size-exclusion was successfully used to separate proteins. In this paper, adsorption-TLC was used to separate proteins. The net charges were calculated for four model proteins, albumin, transferrin, lactoferrin and lysozyme, under different pH values. The suitable pH values for separation were determined according to the results from such calculations. Then, the adsorption isotherms of the four proteins were measured to deduce the ionic strength for appropriate elution conditions. Optimal conditions, 0.01 M bicine and pH 8.50, and a three-step elution process (1st step 0.01 M NaCl, 2nd 0.025 M NaCl, and 3rd 0.10 M NaCl), were obtained. Finally, the four model proteins were successfully separated under these elution condition. PMID:9741103

Luo, Q; Andrade, J D; Caldwell, K D

1998-08-01

99

Rapid characterization of cellular retinoid-binding proteins by high-performance size-exclusion chromatography.  

PubMed

A high-performance size-exclusion chromatographic method was developed for the analysis of cellular retinol and retinoic acid-binding proteins. The chromatographic analysis of the retinol-retinol-binding protein complex or the retinoic acid-retinoic acid-binding protein complex requires 15 min. The use of high-specific-radioactivity retinoid ligand (30-40 Ci/mmol) allows routine detection of 25 fmol of retinoid-binding protein/mg of cytosolic protein. Thus, this method provides a rapid alternative to sucrose density gradient sedimentation analysis of the cellular retinoid-binding proteins. High-performance size-exclusion chromatography is well suited to screening novel tissues, tumors, and cell lines for the presence of retinoid-binding proteins and to the further characterization of these cellular proteins. This method was applied to the characterization of cellular retinol- and retinoic acid-binding proteins in fetal rabbit tissues. Both retinol- and retinoic acid-binding proteins were detected in fetal rabbit brain, intestine, kidney, and lung at a gestational age of 28 days. Neither retinoid-binding protein was detected in 28-day-old fetal rabbit placenta. Specific retinoic acid binding in fetal intestinal cytosol decreased as a function of increasing gestational age. PMID:6312895

Rainier, S; Herrera, J M; McCormick, A M

1983-09-01

100

Electrodialytic membrane suppressors for ion chromatography make programmable buffer generators.  

PubMed

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

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

2012-01-01

101

Determination of aluminium using high performance chelation ion chromatography.  

PubMed

The suitability of high performance chelation ion chromatography (HPCIC) using postcolumn reaction for the separation and determination of dissolved aluminium in complex samples was investigated. Use of a chelating ion-exchanger allowed for differentiation between kinetically labile and kinetically stable species of aluminium. Separation through a combination of chelation and cation-exchange was achieved using a 200 x 4.0 mm id column packed with particles of silica functionalised with iminodiacetic acid, with nitric acid-potassium chloride eluents. A temperature anomaly causing a five-fold increase in column efficiency for aluminium is believed to be a result of localised temperature effects in the particular type of instrument used. Postcolumn reagents investigated for the photometric detection included Tiron, Pyrocatechol Violet, Chrome Azurol S, and Eriochrome Cyanine R. The lowest detection limit (2.7 microg/L for a 100 microL sample volume) was achieved using 0.25 mM Eriochrome Cyanine R in 0.2 M hexamine (pH 6.1) with 1 mM cetyltrimethylpyridium bromide (CTAB). The optimised HPCIC system was applied successfully to the quantification of labile aluminium in paper mill process water. PMID:18563745

Tria, Juliette; Haddad, Paul R; Nesterenko, Pavel N

2008-07-01

102

Size exclusion chromatography of quantum dots by utilizing nanoparticle repelling surface of concentrated polymer brush  

NASA Astrophysics Data System (ADS)

We have found that the concentrated poly(methyl methacrylate) (PMMA) brush showed the very good nanoparticles (NPs) repellency in its good solvent, e.g. tetrahydrofuran (THF). Whereas the oil- and hydro-phobic (fluorinated), hydrophobic and hydrophilic surfaces adsorbed a lot of NPs. The repellency of NPs did not depend on the surface nature of the NPs. Preparing absorption free columns for size exclusion chromatography (SEC) may enable us to separate quantum dots (QDs) and NPs according to their size. By installing the concentrated PMMA brush into silica monolith columns, we tried to achieve SEC of QDs and NPs. The concentrated PMMA brush immobilized silica monolith columns were prepared by surface initiated atom transfer polymerization of MMA. As a result, we have succeeded in separating QDs according to their size. This SEC system may be advantageous because it can be used in good solvents of the brush regardless of the stability of the surface modifier layer on the NPs.We have found that the concentrated poly(methyl methacrylate) (PMMA) brush showed the very good nanoparticles (NPs) repellency in its good solvent, e.g. tetrahydrofuran (THF). Whereas the oil- and hydro-phobic (fluorinated), hydrophobic and hydrophilic surfaces adsorbed a lot of NPs. The repellency of NPs did not depend on the surface nature of the NPs. Preparing absorption free columns for size exclusion chromatography (SEC) may enable us to separate quantum dots (QDs) and NPs according to their size. By installing the concentrated PMMA brush into silica monolith columns, we tried to achieve SEC of QDs and NPs. The concentrated PMMA brush immobilized silica monolith columns were prepared by surface initiated atom transfer polymerization of MMA. As a result, we have succeeded in separating QDs according to their size. This SEC system may be advantageous because it can be used in good solvents of the brush regardless of the stability of the surface modifier layer on the NPs. Electronic supplementary information (ESI) available: Setup for SEC of NPs, images of the columns and separation results using commercially available SEC columns. Those items are available on the WWW or from the author. See DOI: 10.1039/c0nr00157k

Arita, Toshihiko; Yoshimura, Tomoka; Adschiri, Tadafumi

2010-08-01

103

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

PubMed

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

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

2007-07-20

104

Determination of Cyanogenic Compounds in Edible Plants by Ion Chromatography  

PubMed Central

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.

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

2013-01-01

105

Elucidating the redox cycle of environmental phosphorus using ion chromatography.  

PubMed

Historically, it was assumed that reactive, inorganic phosphorus present in pristine environments was solely in the form of orthophosphate. However, this assumption contradicts theories of biogenesis and the observed metabolic behavior of select microorganisms. This paper discusses the role of ion chromatography (IC) in elucidating the oxidation-reduction cycle of environmental phosphorus. These methods employ suppressed-IC, coupled with tandem conductivity and electrospray mass spectrometry detectors to identify and quantify phosphorus oxyanions in natural water, synthetic cosmochemical, and biological samples. These techniques have been used to detect phosphite and orthophosphate in geothermal hot springs. Hypophosphite, phosphite, and orthophosphate have been detected in synthetic schreibersite corrosion samples, and termite extract supernatant. Synthetic schreibersite corrosion samples were also analyzed for two poly-phosphorus compounds, hypophosphate and pyrophosphate, and results show these samples did not contain concentrations above the 1.3 and 2.0 ?M respective 3? limit of detection. These methods are readily adaptable to a variety of matrices, and contribute to the elucidation of the oxidation-reduction cycle of phosphorus oxyanions in the environment. In contrast to most studies, these techniques have been used to show that phosphorus actively participates in redox processes in both the biological and geological world. PMID:21859529

Pech, Herbe; Vazquez, Maria G; Van Buren, Jean; Shi, Lixin; Ivey, Michelle M; Salmassi, Tina M; Pasek, Matthew A; Foster, Krishna L

2011-09-01

106

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

PubMed

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

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

2009-04-01

107

Influence of extraction method on size exclusion chromatography fingerprints of EPS from wastewater sludges.  

PubMed

Extracellular polymeric substances (EPS) were separated using two serial-linked size exclusion chromatography (SEC) columns to obtain detailed fingerprints. The chromatographic profile results were influenced by the nature of biological sludge (activated sludges, anaerobic granules, anaerobic flocculated sludges). Furthermore, our results highlight that EPS fingerprints are also highly dependent on the extraction method. If physical extractions modify only the relative absorbance of the chromatographic peaks, heating during extraction induces significant modifications of the fingerprints, probably owing to better organic matter extraction efficiency as well as an increase in hydrolysis for some compounds but not for EPS extracted from anaerobic granular sludges. This confirms that thermal treatment is a proper method to extract EPS from anaerobic granular sludges. The use of chemical extraction results in major changes on the EPS fingerprints. This work demonstrates that some chromatographic peaks are due to residues from the chemical reagent (such as EDTA, glutaraldehyde) which can modify or form complexes with some EPS macromolecules. As a result, due to its sensitivity to sludge origin and/or extraction procedure, SEC appears to be a suitable tool for an accurate qualitative EPS characterization. PMID:23530346

Bourven, I; Simon, S; Guibaud, G

2013-01-01

108

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

PubMed Central

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

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

2011-01-01

109

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

PubMed

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

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

2012-09-21

110

High yield purification of functional baculovirus vectors by size exclusion chromatography.  

PubMed

Recombinant baculoviruses carrying mammalian expression cassettes or "BacMam" are promising gene delivery vehicles shown to transduce mammalian cells efficiently both in vitro and in vivo. These viruses are vectors of choice because they are non-pathogenic; able to accommodate large foreign DNA inserts and can be produced at high titers. Hence, the demand for pure and functional baculovirus vectors for gene delivery experiments is anticipated in the future. The main goal of this work is to develop a simple and efficient process to purify recombinant baculovirus derived from Autographa californica multiple nucleopolyhedrovirus from a culture supernatant by size exclusion chromatography. The final yields obtained for total and infectious particles were 1.39 x 10(11) and 1.02 x 10(10) and recoveries of 25% and 24%, respectively. The virus was purified from the majority of the protein contaminants as shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Negative stain electron microscopy demonstrated that >95% of the purified virus was intact particles with shape like rod and average diameter and length of 60 and 266 nm, respectively. Transduction of 293 human embryonic kidney cells by a purified GFP-expressing BacMam at a multiplicity of transduction of 200 resulted in 36% positive cell population. PMID:17306891

Transfiguracion, Julia; Jorio, Hasnaa; Meghrous, Jamal; Jacob, Danielle; Kamen, Amine

2007-06-01

111

Analysis of residuum desulfurization by size exclusion chromatography with element specific detection. Part II  

SciTech Connect

Heavy crude residua are analyzed by side exclusion chromatography with element specific detection (SEC-ICP), to elucidate structural information about the S-containing compounds. These compounds appear to fall into two categories: those which are 1) moderately small components (probably thiophenic), and 2) larger components associated with apparent precursors of asphaltenes. The effects of thermal hydroprocessing on the S-containing compounds were also examined. High and moderate thermal severity appear to, in addition to removing S: 1) remove the larger S-containing compounds, 2) shift the total S profile to smaller molecular size, and 3) form S-containing compounds not existent in the feed. Low thermal severity appears to only partially remove the larger S-containing compounds. These results indicate the S-containing compounds behave similarly to the metal-containing compounds under the same processing conditions. Possible binding site relationships between some of the S- and metal-containing compounds in heavy crudes and residua are discussed. The authors observed S and V correlations in both feeds and products, suggesting a relationship between the S and V at the molecular level.

Reynolds, J.G.; Biggs, W.R.

1988-01-01

112

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

NASA Astrophysics Data System (ADS)

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.

Pawcenis, Dominika; Koperska, Monika A.; Milczarek, Jakub M.; ?ojewski, Tomasz; ?ojewska, Joanna

2014-02-01

113

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

PubMed

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

Liu, Guangliang; Cai, Yong

2013-11-15

114

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

Microsoft Academic Search

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

Heike Jerosch; Bertrand Lavédrine; Jean-Claude Cherton

2001-01-01

115

Chromatography  

NSDL National Science Digital Library

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

Hardy, James K.

2011-05-16

116

Ion chromatography characterization of polysaccharides in ancient wall paintings.  

PubMed

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

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

2002-08-30

117

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  

Microsoft Academic Search

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 Cââ elute through the porosity of the column. Detection of aliphatics was defined by use of an evaporative light scattering (ELS) detector

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

2006-01-01

118

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

SciTech Connect

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

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

1988-08-01

119

Simultaneous determination of arsenic species by ion chromatography-inductively coupled plasma mass spectrometry  

Microsoft Academic Search

Six arsenic species, arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine, were separated by coupled column ion chromatography using carbonate and nitric acid as eluents, and were detected by inductively coupled plasma mass spectrometry. Coupling of an anion column with a cation column made the simultaneous determination of both the cationjic and the anionic arsenic species possible by ion

Pertti Teräsahde; Mari Pantsar-Kallio; Pentti K. G. Manninen

1996-01-01

120

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

121

[Determination of hydrazine ion in explosion dust of liquid explosive by ion chromatography].  

PubMed

A method for the determination of hydrazine ion in explosion dust of liquid explosive has been established by ion chromatography. The hydrazine ion in an explosion dust sample was extracted with deionized water by sonification and centrifugation. The large molecules and solid particles in supernatant were removed by an OnGuard II RP column and a 0.22 microm filtration membrane, respectively. The filtrate was separated on an IonPac CS-12A column with isocratic elution of 5 mmol/L methanesulfonic acid (MSA). Then 0.1 mol/L NaOH solution was post-column added and the resultant solution was detected by an ampere detector with golden electrode. The results showed that, the calibration curve was linear in the range of 0.02 - 2.0 mg/L with a correlation coefficient (r2 ) of 0.999 7. The limits of detection (LOD, S/N = 3) and quantification (LOQ, S/N = 10) of hydrazine were 5.0 microg/L and 16.6 microg/L, respectively. The recoveries ranged between 95.4% and 99.1% with the relative standard deviations (RSDs, n = 5) of 2.1% - 3.3%. The hydrazine content in a real explosion dust sample of liquid explosive was 10.3 mg/kg by this method. The method is simple, accurate, and suitable for the quantitative detection of hydrazine ions in explosion dust of liquid explosive, and the method can meet the needs of the criminal evidence identification work. PMID:24392633

Wang, Yong; Geng, Qing; Zuo, Yuexian; Zhou, Xinwen; Lian, Hongzhen; Pan, Guangwen

2013-09-01

122

Preliminary studies on selenium-containing proteins in Brassica juncea by size exclusion chromatography and fast protein liquid chromatography coupled to ICP-MS.  

PubMed

An approach for screening and resolving selenium-containing plant proteins was developed based on the combination of sample preparation and multi-dimensional liquid chromatography coupled to ICP-MS. Different protein extraction protocols were investigated. A 24 h dodecylsulfate-mediated protein extraction in a sonication bath followed by acetone precipitation was found to be optimal. The use of different protein precipitate solubilizing agents (sodium dodecyl sulfate media and Tris-HCl buffer) demonstrates possible fractionation of the selenium-containing proteins. Selenium-containing protein screening and fractionation were carried out by means of SEC-ICP-MS. High molecular weight selenium containing proteins were solubilized with a sodium dodecyl sulfate-containing buffer, whereas the low molecular weight compounds were released into a Tris-HCl buffer. Size exclusion chromatography-fast protein liquid chromatography coupled to ICP-MS allowed separation and detection of several selenium-containing proteins in Se-supplemented wild type Brassica juncea plant, a fast growing selenium accumulator. PMID:14752553

Mounicou, Sandra; Meija, Juris; Caruso, Joseph

2004-02-01

123

Optimization of reversed-phase ion-pair chromatography by over-pressurized thin-layer chromatography III. Over-pressurized thin-layer chromatography using 10-camphor sulfonic acid as ion-pair reagent  

Microsoft Academic Search

Summary  The use of over-pressurized thin-layer chromatography in ion pair system using acidic type pairing reagent has been studied.\\u000a The most important aspect when reversed phase ion-pair TLC system is used to apply a suitable procedure for pre-treatment\\u000a of the sorbents. Because of the acidic type of ion pair reagents cannot be bounded to the surface of the layer by immersion

G. Szepesi; M. Gazdag; Zs. Pap-Sziklay; Z. Végh

1984-01-01

124

Ion-Pair Chromatography of Metal Complexes of Unithiol in the Presence of Quaternary Phosphonium Salts  

Microsoft Academic Search

The chromatographic behavior of heavy-metal (Pb, Cd, Cu, Hg, and Ni) complexes of unithiol was studied by ion-pair reversed-phase chromatography using new ion-pair reagents: tetrabutylphosphonium and tributylhexadecylphosphonium bromides. The dependence of the retention of metal unithiolates on the nature and concentration of ion-pair reagents, concentrations of an organic solvent and inorganic salts in the mobile phase, and the pH of

E. N. Shapovalova; M. N. Ofitserova; E. V. Savost'yanova; O. A. Shpigun

2001-01-01

125

DETERMINATION OF TRACE ANIONS IN WATER BY MULTIDIMENSIONAL ION CHROMATOGRAPHY  

EPA Science Inventory

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

126

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

PubMed

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

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

2008-02-29

127

Speciation of aluminium in tea infusions studied by size exclusion chromatography with detection by post-column reaction.  

PubMed

Aluminium-organic species in tea infusions were studied by size exclusion chromatography, using a Superose 12 HR column, a mobile phase of 0.12 mol l-1 tris(hydroxymethyl)aminomethane adjusted to pH 5.5 and detection by UV-visible spectrophotometry. Aluminium was detected after post-column reaction with pyrocatechol violet at 585 nm and the organic material was detected at 280 nm. Teas of different origin were analyzed; the results indicate that aluminium is bound to the same relatively narrow size-range of large organic molecules in the tea infusions, irrespective of the origin of the tea. PMID:9397596

Flaten, A K; Lund, W

1997-11-14

128

Multi-column step-gradient chromatography system for automated ion exchange separations  

SciTech Connect

A multi-column step-gradient chromatography system has been designed to perform automated sequential separations of radionuclides by ion exchange chromatography. The system consists of a digital programmer with automatic stream selection valve, two peristaltic pumps, ten columns, and a fraction collector. The automation allows complicated separations of radionuclides to be made with minimal analyst attention and allows for increased productivity and reduced cost of analyses. Results are reported for test separations on mixtures of radionuclides by the system.

Rucker, T.L.

1985-01-01

129

Water extraction of plant tissues for analysis by ion chromatography  

Microsoft Academic Search

High pressure liquid chromatography (HPLC)?grade water was evaluated as an alternative extraction reagent to acid extraction of plant tissue. Green and red bell pepper fruit (Capsium annuum var. annuum L.), cultivar Pip; sweet corn internodes (Zea mays L.), cultivar Florida Staysweet; cabbage wrapper leaves (Brassica oleracea L. Capitata group), cultivar Solid Blue 770; peach leaves [Prunus persica (L.) Batsch], cultivar

V. M. Russo; S. V. Karmarkar

1998-01-01

130

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

NASA Technical Reports Server (NTRS)

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.

Otterson, D. A.

1978-01-01

131

Chromatography  

NSDL National Science Digital Library

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

Boston, Wgbh

2002-01-01

132

Determination of the big head carp myofibrillar (Aristichthys nobilis) adenosine triphosphatase activity by ion chromatography.  

PubMed

A method for the determination of adenosine triphosphatase (ATPase) activity of myofibrils of big head carp by using ion chromatography was introduced. Adenosine triphosphate (ATP), adenosine diphosphate (ADP) and orthophosphate (Pi) were separated completely. Recoveries for ATP, ADP and Pi were 98+/-5%, 97+/-4% and 98+/-5%, respectively. Pi liberated from ATP during reaction was monitored by ion chromatography using the suggested method. This method was applicable to the determination of myofibrils ATPase activity for quick quality evaluation of surimi. PMID:16701679

Gao, Rui-chang; Xue, Chang-hu; Yuan, Li; Li, Zhao-jie; Xue, Yong; Cui, Fengxia; Sun, Yan

2006-06-23

133

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

NASA Astrophysics Data System (ADS)

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

Xie, Wenchun

134

Determination of phosphite in a eutrophic freshwater lake by suppressed conductivity ion chromatography.  

PubMed

The establishment of a sensitive and specific method for the detection of reduced phosphorus (P) is crucial for understanding P cycle. This paper presents the quantitative evidence of phosphite (P, +3) from the freshwater matrix correspondent to the typically eutrophic Lake Taihu in China. By ion chromatography coupled with gradient elution procedure, efficient separation of micromolar levels of phosphite is possible in the presence of millimolar levels of interfering ions, such as chloride, sulfate, and hydrogen carbonate in freshwater lakes. Optimal suppressed ion chromatography conditions include the use of 500 ?L injection volumes and an AS11 HC analytical column heated to 30 °C. The method detection limit of 0.002 ?M for phosphite was successfully applied for phosphite determination in natural water samples with recoveries ranging from 90.7 ± 3.2% to 108 ± 1.5%. Phosphite in the freshwater matrix was also verified using a two-dimensional capillary ion chromatography and ion chromatography coupled with mass spectrometry. Results confirmed the presence of phosphite in Lake Taihu ranging from 0.01 ± 0.01 to 0.17 ± 0.01 ?M, which correlated to 1-10% of the phosphate. Phosphite is an important component of P and may influence biogeochemical P cycle in lakes. PMID:22954139

Han, Chao; Geng, Jinju; Xie, Xianchuan; Wang, Xiaorong; Ren, Hongqiang; Gao, Shixiang

2012-10-01

135

Comparison of different transition metal ions for immobilized metal affinity chromatography of selenoprotein P from human plasma  

Microsoft Academic Search

Cu2+, Ni2+, Zn2+, Co2+ and Cd2+ were evaluated in metal ion affinity chromatography for enrichment of selenoprotein P, and immobilized Co2+ affinity chromatography was found to be the most selective chromatographic method. The chromatography was performed by fast protein liquid chromatography and the fractionation was followed by analysis of the collected fractions for selenium by inductively coupled plasma mass spectrometry.

U Sidenius; O Farver; O Jøns; B Gammelgaard

1999-01-01

136

Ion-exchange sorption and preparative chromatography of biologically active materials  

SciTech Connect

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.

Samsonov, G.V.

1986-01-01

137

Determination of lanthanides by ion chromatography. Separation and retention mechanism  

Microsoft Academic Search

As an extension of our previous studies, in this work, an ion exchange method for the determination of rare earths in a YbF3 matrix, used for optical fibres manufacture, was improved. The separation has been performed on a mixed bed column, IonPac CS5 containing both anion and cation exchange sites, by oxalic and diglycolic acids eluents and post-column spectrophotometric detection.

Maria Concetta Bruzzoniti; Edoardo Mentasti; Corrado Sarzanini

1997-01-01

138

Serially interfaced gas chromatography\\/Fourier transform infrared spectrometer\\/ion trap mass spectrometer system  

Microsoft Academic Search

A serial gas chromatography\\/Fourier transform infrared spectrometer\\/mass spectrometer (GC\\/FTIR\\/MS) system has been developed with an ion trap detector or mass analyzer that is interfaced to the light pipe in the FTIR spectrometer. A modification of the manufacturer-supplied open-split interface to the ion trap was required to obtain chromatographic results free of discrimination and activation effects. The flow rate of the

Edwin S. Olson; John W. Diehl

1987-01-01

139

Zonal rate model for stacked membrane chromatography part II: characterizing ion-exchange membrane chromatography under protein retention conditions.  

PubMed

The Zonal Rate Model (ZRM) has previously been shown to accurately account for contributions to elution band broadening, including external flow nonidealities and radial concentration gradients, in ion-exchange membrane (IEXM) chromatography systems operated under nonbinding conditions. Here, we extend the ZRM to analyze and model the behavior of retained proteins by introducing terms for intra-column mass transfer resistances and intrinsic binding kinetics. Breakthrough curve (BTC) data from a scaled-down anion-exchange membrane chromatography module using ovalbumin as a model protein were collected at flow rates ranging from 1.5 to 20 mL min(-1). Through its careful accounting of transport nonidealities within and external to the membrane stack, the ZRM is shown to provide a useful framework for characterizing putative protein binding mechanisms and models, for predicting BTCs and complex elution behavior, including the common observation that the dynamic binding capacity can increase with linear velocity in IEXM systems, and for simulating and scaling separations using IEXM chromatography. Global fitting of model parameters is used to evaluate the performance of the Langmuir, bi-Langmuir, steric mass action (SMA), and spreading-type protein binding models in either correlating or fundamentally describing BTC data. When combined with the ZRM, the bi-Langmuir, and SMA models match the chromatography data, but require physically unrealistic regressed model parameters to do so. In contrast, for this system a spreading-type model is shown to accurately predict column performance while also providing a realistic fundamental explanation for observed trends, including an observed increase in dynamic binding capacity with flow rate. PMID:22012741

Francis, Patrick; von Lieres, Eric; Haynes, Charles

2012-03-01

140

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

Microsoft Academic Search

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

B. Wiedenman; T. White

2009-01-01

141

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

Microsoft Academic Search

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

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

2012-01-01

142

Analyses of Vegetable Oil Triacylglycerols by Silver Ion High Performance Liquid Chromatography with Flame Ionization Detection  

Microsoft Academic Search

Silver ion high performance liquid chromatography with a commercially available column with a simple isocratic mobile phase of acetonitrile in hexane and flame ionization detection was employed to separate and quantitate triacylglycerol species of vegetable oils. Coconut, palm, cottonseed, olive, safflower, sunflower, corn, pumpkinseed, linseed, soybean, and canola oils were analyzed, as well as randomized corn and soybean oils, and

W. E. Neff; R. O. Adlof; G. R. List; M. El-Agaimy

1994-01-01

143

Measurements of SO2 and Sulfate Concentrations in Car Exhaust Using Ion Chromatography.  

National Technical Information Service (NTIS)

In the framework of the analysis of non-limited exhaust gas components, an ion chromatography system is used for the detection of inorganic trace components. Processes for the detection of sulphur dioxide and sulphate are developed, and the process coeffi...

A. Hartung A. Behte A. Postulka

1989-01-01

144

Heart-cutting two-dimensional (size exclusion x reversed phase) liquid chromatography-mass spectrometry analysis of flavonol glycosides from leaves of Maytenus ilicifolia.  

PubMed

Two-dimensional liquid chromatography-electrospray ionization mass spectrometry was employed to analyze flavonol glycosides present in leaves of Maytenus ilicifolia, frequently used in traditional Brazilian medicine. Since they contain many flavonol glycosides, including isomers, one-dimensional liquid chromatography did not give complete separation and identification, yielding overlapping of compounds with different molecular weights. Thus, employing size exclusion chromatography in the first and reversed phase in the second dimension, a great number of flavonol glycosides could be identified and its relative abundances determined. The majority of glycosides contained kaempferol or quercetin as aglycones, and glycosides with previously unreported structures were also present and characterized. PMID:19062030

de Souza, Lauro M; Cipriani, Thales R; Sant'ana, Carolina F; Iacomini, Marcello; Gorin, Philip A J; Sassaki, Guilherme L

2009-01-01

145

Sulfobutyl ether-?-cyclodextrin fingerprint using ion pair reversed-phase chromatography  

Microsoft Academic Search

Summary  A liquid chromatography (LC) method using volatile ion-pairing agent and evaporative light scattering detection has been developed\\u000a for the analysis of sulfobutyl-ether-?-cyclodextrins (SBE-?-CD). Different protonated aliphatic amines (triethylamine, pentylamine\\u000a and heptylamine) were evaluated as volatile ion-pairing agents. The effects on SBE-?-CD retention of the n-alkyl chain length\\u000a and concentration (0.5 to 50 mM) of the ion-pairing agent and the effect

S. Grard; C. Elfakir; M. Dreux

1999-01-01

146

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

Microsoft Academic Search

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

Takeshi Matsuzaki; Yoshinori Inoue; Tetsuo Ookubo; Sadao Mori

1980-01-01

147

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

PubMed

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

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

2012-05-01

148

Fluorescence determination of sulphobutylether-beta-cyclodextrin in human plasma by size exclusion chromatography with inclusion complex formation.  

PubMed

A selective method for the determination of sulphobutylether-beta-cyclodextrin (SBECD) in human plasma has been developed and validated over the range 4-200 microg ml(-1). SBECD is extracted from plasma using end-capped cyclohexyl solid phase extraction cartridges. This is followed by high performance size exclusion chromatography with a mobile phase consisting of 1-naphthol (0.1 mM) in methanol-potassium nitrate (0.2 M) (1:9 v/v), 1 ml min(-1). The high aqueous content of the mobile phase quenches the fluorescence of 1-naphthol. However, the naphthol forms an inclusion complex with SBECD. The non-polar 'bucket' environment of the inclusion region restores the fluorescence, which is measured at excitation and emission wavelengths of 290 and 360 nm, respectively, when SBECD elutes from the column. PMID:10815720

Gage, R; Venn, R F; Bayliss, M A; Edgington, A M; Roffey, S J; Sorrell, B

2000-06-01

149

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

PubMed

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

Wang, Zhengxin; Marcus, R Kenneth

2014-07-18

150

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

PubMed

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

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

2013-01-14

151

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

PubMed

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 µg L(-1) for Fe(II) and 3 µg 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

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

2012-01-01

152

Structure of the mouse glucocorticoid receptor: rapid analysis by size-exclusion high-performance liquid chromatography.  

PubMed

Gel-exclusion high-performance liquid chromatography (HPLC) has been used to separate the untransformed from the transformed glucocorticoid receptor (GC-R) extracted from mouse AtT-20 cells. With 200 mM potassium phosphate as the eluent, an efficient separation of the forms of the GC-R is attained in 15-20 min. The untransformed cytosolic GC-R elutes from the column with a Stokes radius (Rs) of 8.2-8.6 nm, as do the molybdate-stabilized GC-R, the purified untransformed GC-R, and the cross-linked cytosolic GC-R. GC-R transformed in vitro by either ammonium sulfate precipitation, KCl treatment, or G-25 chromatography elutes with an Rs of 5.7-6 nm. Also, GC-R extracted from the nucleus with either 0.3 M KCl or 2 mM sodium tungstate, or purified by two cycles of DNA-cellulose chromatography, has an Rs of 5.5-6.3 nm. The data are identical either in the presence or in the absence of 20 mM Na2MoO4, suggesting that molybdate is not causing aggregation to produce a larger Rs value than that of the native receptor. Vertical tube rotor sucrose gradient ultracentrifugation of cytosol produces three forms of the GC-R: 9.1 S, 5.2 S, and 3.8 S. Sequential analysis of the GC-R forms by HPLC and vertical tube rotor ultracentrifugation and vice versa allows for the hydrodynamic determination of molecular weight within a very short time period (2-3 h total).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3707935

LaPointe, M C; Chang, C H; Vedeckis, W V

1986-04-22

153

Metalloprotein separation and analysis by directly coupled size exclusion high-performance liquid chromatography inductively coupled plasma mass spectroscopy.  

PubMed

The feasibility of using directly coupled size exclusion high-performance liquid chromatography inductively coupled plasma mass spectroscopy (HPLC/ICP-MS) for the separation and subsequent elemental analysis of metalloproteins in biological samples has been studied. Data, on up to eight elements, was acquired simultaneously and the reconstructed elemental profiles from the chromatographed samples were quantified by flow injection analysis. Absolute and relative detection limits, reproducibility, operational dynamic range, and linearity of response were initially evaluated by analyzing standards of metallothionein protein of known elemental composition for Cd, Zn, and Cu. There was evidence of displacement of Zn from the protein during chromatography and the substitution of Cu sequestered from the mobile phase. Cd associated with the protein was fully recovered during chromatography. Memory effects, due to protein adsorption to the glassware in the torch box, were minimal and there was no degradation of the resolution of the chromatographed peak during extended transport through the HPLC/ICP-MS interface. The versatility of the technique has been demonstrated by the quantitative multi-element analysis of cytosolic metal-binding proteins separated from the polychaete worm Neanthes arenaceodentata. Fidelity of analysis has been demonstrated by two independent procedures: first, by comparing the elemental profiles obtained by directly aspirating the HPLC eluant into the ICP-MS to those obtained by collecting fractions and quantifying the metal content of the proteins in the conventional analytical mode; second, by comparing the stable isotopic profiles for 114Cd obtained by simultaneous ICP-MS analysis with radiometric profiles of 109Cd obtained by counting radioactivity associated with collected fractions.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2363489

Mason, A Z; Storms, S D; Jenkins, K D

1990-05-01

154

Detection of Alkylaminium Salts in Particulate Matter by Ion Chromatography  

NASA Astrophysics Data System (ADS)

Smog chamber experiments were conducted to determine how amines react to form particles, specifically amine salts, in the atmosphere. All of the experiments were performed in a smog chamber at University of California Riverside's College of Engineering Center for Environmental Research and Technology (CE-CERT). A Particle Into Liquid Sampler Ion Chromatograph (PILS-IC) was used to determine the concentration of the amine salts formed during the experiment. It became apparent that the amines (trimethylamine, diethylamine, and butylamine) behave differently in the presence of oxidants. The oxidants used were N2O5 and hydroxyl, both under varying levels of humidity (0 - 40%). By order of decreasing amount, the amines that produced the highest concentration of amine salts were: diethylamine, butylamine, and trimethylamine. It was also discovered that the hydroxyl radical had a higher tendency to oxidize the carbon side chain of the amine, rather than form the salt as in the case of N2O5.

Praske, E.; Lee, S. A.; Tang, X.; Cocker, D. R.; Silva, P. J.; Purvis-Roberts, K. L.

2012-04-01

155

Determination of biogenic amines in cheese by ion exchange chromatography.  

PubMed

A sensitive, fully automated method, yielding reproducible results, was developed for the determination of relevant biogenic amines in cheese. Histamine, tyramine, putrescine, cadaverine, tryptamine, agmatine, spermidine and spermine were separated in the ion exchanger of OSTION LG ANB column of the automatic amino acid analyser Mikrotechna 339 T. Elution was carried out at 60 degrees C using a system of two buffers. The samples were extracted and precipitated by trichloroacetic acid and purified, after removal of fat, by membrane filtration. The recovery for individual amines in cheese ranged between 86% and 108%. The detection limit was of 1-5 mg of the respective amine per 1 kg of cheese and the method was linear within the dose range of 0.1-10 micrograms (for tryptamine 0.5-10 micrograms). PMID:10702996

Standara, S; Veselá, M; Drdák, M

2000-02-01

156

Analysis of glucosylceramides from various sources by liquid chromatography-ion trap mass spectrometry.  

PubMed

Liquid chromatography-mass spectrometry is one of the most powerful methods for the identification and detection of chemical structures of lipids. In this study, we attempted to identify the chemical structures of glucosylceramides from maize, rice, mushroom (maitake) and sea cucumber by liquid chromatography-ion trap mass spectrometry. For structural analysis of glucosylceramides, [M+H]+, [M+H-18]+ or [M+H-162]+ in the positive scan mode was used for MS/MS analysis to obtain product ion spectra. The typical signals which are characteristic for the sphingoid base moieties were observed while the isomers could not be distinguished. This method should be useful for the structural determination of diverse glucosylceramide molecular species. PMID:20513973

Sugawara, Tatsuya; Aida, Kazuhiko; Duan, Jingjing; Hirata, Takashi

2010-01-01

157

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

SciTech Connect

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

Goheen, Steven C.; Gibbins, Betty M.

2000-01-01

158

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

Microsoft Academic Search

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

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

2007-01-01

159

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

Microsoft Academic Search

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

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

1984-01-01

160

Analysis of Urushiols by Liquid Chromatography\\/Atmospheric Pressure Chemical Ionization?Ion Trap Mass Spectrometry  

Microsoft Academic Search

Urushiol derivatives in a natural polymeric paint (urushi), obtained from Korean tapping lacquer trees were separated by reverse phase liquid chromatography and analyzed by on?line atmospheric pressure chemical ionization ion trap mass spectrometry (LC\\/APCI?ITMS). The molecular weight and molecular structure information for each peak were obtained from full scan spectrum and collision induced dissociation (CID) spectrum, respectively. Each urushiol isomer

Jong Oh Choi; Jeong Soo Yang; Dai Woon Lee

2003-01-01

161

Identification and quantification of glucosinolates in rapeseed using liquid chromatography–ion trap mass spectrometry  

Microsoft Academic Search

A rapid and sensitive method for the speciation and quantification of glucosinolates in rapeseed is described. The method\\u000a combines liquid chromatography (LC) with ion trap mass spectrometry (ITMS) detection. Electrospray ionization (ESI) has been\\u000a chosen as the ionization technique for the on-line coupling of LC with ITMS. Glucosinolates are extracted from different rapeseeds\\u000a with MeOH and the extracts are cleaned-up

Silvia Millán; M. Carmen Sampedro; Patricia Gallejones; Ander Castellón; Maria L. Ibargoitia; M. Aranzazu Goicolea; Ramón J. Barrio

2009-01-01

162

Surfactant-sensitized post-column reaction with xylenol orange for the determination of lanthanides by ion chromatography  

Microsoft Academic Search

The presence of the cationic surfactants cetylpyridinium chloride and hexadecyltrimethylammonium bromide in an alkaline 40% methanol medium was found to enhance sensitivity when xylenol orange is employed as the post-column reaction reagent for the determination of lanthanides by dynamic ion chromatography. Detection of individual lanthanides was carried out at 618 nm after separation by cation-exchange chromatography with gradient elution on

Eduardo A. Gautier; Raquel T. Gettar; Roberto E. Servant; Daniel A. Batistoni

1997-01-01

163

Large-scale Analysis of in Vivo Phosphorylated Membrane Proteins by Immobilized Metal Ion Affinity Chromatography and Mass Spectrometry  

Microsoft Academic Search

Global analyses of protein phosphorylation require spe- cific enrichment methods because of the typically low abundance of phosphoproteins. To date, immobilized metal ion affinity chromatography (IMAC) for phos- phopeptides has shown great promise for large-scale studies, but has a reputation for poor specificity. We in- vestigated the potential of IMAC in combination with cap- illary liquid chromatography coupled to tandem

Thomas S. Nuhse; Allan Stensballe; Ole N. Jensen; Scott C. Peck

2003-01-01

164

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

PubMed

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

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

2006-05-10

165

[Determination of trace perchlorate in groundwater by solid phase extraction-ion chromatography].  

PubMed

A comprehensive analytical method based on solid phase extraction-ion chromatography (SPE-IC) has been developed for the determination of trace perchlorate in groundwater. An amount of 0.7 liter of groundwater was enriched by a solid phase extraction column after pretreatment to remove the interference ions and then the column was eluted by 6 mL 1% NaOH solution. After filtration of the concentrated liquor with a filter membrane (0.45 microm), the liquor was analyzed on an ion chromatograph (IC) equipped with an Ion Pac AS20 separation column and a 50 microL injection loop, eluted with 40 mmol/L KOH solution. The method detection limit (MDL) and limit of determination (LOD) of perchlorate were 0.15 microg/L and 0.60 microg/L, respectively. The recovery was in the range of 99.7%-100.5% when the sampling concentrations were in the range of 1-15 microg/L. The method is economical and effective. It can be applied to determine trace perchlorate in groundwater. The perchlorate in groundwater samples got from the areas surrounding Harbin was determined by this method. The relative errors were in the range of 1.85%-9.24% between the results got by the SPE-IC and ion chromatography-tandem single quadrupole mass spectrometry. PMID:22667096

Ye, Long; You, Hong; Yao, Jie; Su, Huailong

2012-01-01

166

Use of Ion Chromatography-DC Plasma Atomic Emission Spectrometry for the Speciation of Trace Metals: Progress Report.  

National Technical Information Service (NTIS)

Purpose of this research is to study the interfacing of ion chromatography (IC) with dc plasma atomic emission spectrometry (DCPAES), tailoring the combined system to trace metal speciation in aqueous solutions. The DCPAES will serve as an element selecti...

I. T. Urasa

1987-01-01

167

Simultaneous determination of organic and cationic species in explosives residues with column-switching liquid chromatography-ion chromatography system.  

PubMed

A new column-switching method has been proposed for the determination of 14 organic explosives (1,3,5,7-tetranitro-N-methylaniline, 1,3,5-trinitro-1,3,5-triazacyclohexane, 1,3,5-trinitrobenzene, 1,3-dinitrobenzene, nitrobenzene, 2,4,6-N-tetranitro-N-methylaniline, Trinitrotoluene, 4-amino-2,6-dinitrotoluene, 2-amino-4,6-dinitrotoluene, 2,6-dinitrotoluene, 2,4-dinitrotoluene, 2-nitrotoluene, 4-nitrotoluene, and 3-nitrotoluene) and/or five inorganic cations (Na(+), NH(4)(+), K(+), Mg(2+), and Ca(2+)) using liquid chromatography linked to ion chromatography by a switching valve. The mobile phase was methanol-water (40/60, v/v) for a C18 reversed-phase column and 3 mM of methanesulfonic acid (pH 2.5) for a cation-exchange column, respectively. Under the optimal conditions, the 14 organic explosives and the five inorganic cations were separated and detected simultaneously within 45 min. The limits of detection (S/N = 3) of the 14 organic explosives and the five inorganic cations were in the range of 0.0048-0.0333 mg/L and 0.0116-0.1851 mg/L, respectively. The linear correlation coefficients were 0.9971-0.9999, and the relative standard deviation of the retention time and the peak area were 0.02-0.31% and 0.51-3.64%, respectively. The method was successfully applied to the determination of organic explosives and inorganic cations in dust samples. PMID:21859537

Xie, Peijin; Xu, Jingang; Hu, Zhenzhen; El-Sepai, Fawzi; Peimin, Zhang; Zhu, Yan

2011-09-01

168

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

Microsoft Academic Search

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

Liang K. Tan; John E. Dutrizac

1985-01-01

169

Size-exclusion high-performance liquid chromatography in analysis of protein and peptide epitopes.  

PubMed

Size-exclusion HPLC provides direct observation of antibody-antigen interactions in free solution without chemical modification of either component. HPLC data collection systems are now a routine resource in both academic and industrial research laboratories. Monoclonal antibodies are, in principle, homogeneous reagents whose interactions with epitope are suitable for unambiguous quantitative characterization. HPLC-based methods, therefore, have the potential to contribute significantly to efficient quantitative characterization of monoclonal antibodies in studies directed to the fundamental physiological roles of these molecules as well as to the optimized selection and quality control of these reagents in biotechnical applications such as represented by the immunodiagnostic industry. In many cases, HPLC-based methods may represent the simplest and most rapid approach for evaluation of relative epitope specificities and affinity/kinetic characteristics of interaction. PMID:2481206

Stevens, F J

1989-01-01

170

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

PubMed

Current European Commission Directives on foods for infants and young children places emphasis on the control of pesticide residues at levels below 10 ?g 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 ?g 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

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

2012-11-15

171

A four-electrode microconstant direct current resistance detector for ion chromatography applying ion-exchange membrane and porous electrode.  

PubMed

A four-electrode microconstant direct current resistance detector for ion chromatography not sensitive to the effects of electrode polarization, capacitance, and electrolysis by-products is proposed. A constant current of microampere magnitude is applied across the current electrodes of the four-electrode device, and the voltage responses between the detection probes are directly picked up by a high input impedance instrumentation amplifier. The ion-exchange membranes, which separate the detection chamber from the electrolysis chambers, enable the measurement of solution resistance free of the interference of electrolysis by-products. Two resin beds in the detection chamber serve as ion conductors while reduce the dead volume of the detector. Recycled detection effluent supplies water for the electrolysis reactions at the current electrodes to sustain constant current in solution. The porous detection probes provide microchannel for the flowing solution while indicating signals. Owing to the constant current excitation, the electronics setup becomes simple. The cell configuration, operating principle, electronics, and error analysis of this detection mode are discussed along with their use for suppressed anion chromatography. Experimental data show that this four-electrode direct current detection mode is comparable to conventional two-electrode alternating current method. PMID:20801342

Huang, Weixiong; Chen, Huabin; Su, Yuhua; Hu, Rongzong

2010-09-15

172

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

PubMed

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

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

2013-10-17

173

Acid-rain monitoring in East Asia with a portable-type ion-exclusion–cation-exchange chromatographic analyzer  

Microsoft Academic Search

A monitoring system consisting of a portable-type conductimetric ion-exclusion–cation-exchange chromatographic (CEC) analyzer and a meteorological satellite data analyzer has been investigated for the evaluation of the effects of acid precipitation on natural and urban environments in East Asia. The portable ion-exclusion–CEC analyzer uses a polymethacrylate-based weakly acidic cation-exchange resin column in the H+-form and a weak-acid eluent (tartaric acid–methanol–water) and

K. Tanaka; K. Ohta; P. R. Haddad; J. S. Fritz; K.-P. Lee; K. Hasebe; A. Ieuji; A. Miyanaga

1999-01-01

174

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

PubMed Central

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.

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

175

Determination of pharmaceutically related compounds by suppressed ion chromatography: III. Role of electrolytic suppressor design.  

PubMed

For the hyphenation of ion chromatography to nebulising detectors or mass spectrometry, suppression of the non-volatile ionic eluent to water is a required step to avoid elevated detector baselines. Presented here is a study of three new designs of electrolytic suppressors, incorporating high ion-exchange capacity screens and high ion-exchange capacity membranes in different thickness and compositions. These designs aim to minimise hydrophobic interactions of the suppressor with organic analytes and to provide higher compatibility with eluents containing acetonitrile. In comparison with a commercially available electrolytic suppressor and also a commercially available chemical suppressor, the new high-capacity suppressor showed superior performance, exhibiting minimal interactions with a test set of analytes under the examined conditions. This led to the attainment of high recoveries of the analytes after suppression (93-99% recovery) and significantly reduced band broadening during suppression. The new suppressor has been shown to perform well under both isocratic and gradient elution conditions. PMID:22377470

Karu, Naama; Dicinoski, Greg W; Hanna-Brown, Melissa; Srinivasan, Kannan; Pohl, Christopher A; Haddad, Paul R

2012-04-13

176

Ultraperformance liquid chromatography with electrospray ionization ion trap mass spectrometry for chondroitin disaccharide analysis.  

PubMed

Chondroitin sulfate (CS) has an important role in cell division, in the central nervous system, and in joint-related pathologies such as osteoarthritis. Due to the complex chemical structure and biological importance of CS, simple, sensitive, high resolution, and robust analytical methods are needed for the analysis of CS disaccharides and oligosaccharides. An ion-pairing, reversed-phase, ultraperformance liquid chromatography (IPRP-UPLC) separation, coupled to electrospray ionization mass spectrometry with an ion trap mass analyzer, was applied for the analyses of CS-derived disaccharides. UPLC separation technology uses small particle diameter, short column length, and elevated column temperature to obtain high resolution and sensitivity. Hexylamine (15 mM) was selected as the optimal ion-pairing reagent. PMID:19769936

Solakyildirim, Kemal; Zhang, Zhenqing; Linhardt, Robert J

2010-02-01

177

Ultraperformance Liquid Chromatography with Electrospray Ion Trap Mass Spectrometry for Chondroitin Disaccharide Analysis  

PubMed Central

Chondroitin sulfate (CS) has an important role in cell division, in the central nervous system, and in joint related pathologies such as osteoarthritis. Due to the complex chemical structure and biological importance of CS, simple, sensitive, high-resolution, and robust analytical methods are needed for the analysis of CS disaccharides and oligosaccharides. An ion pairing, reversed-phase, ultraperformance liquid chromatography (IPRP-UPLC) separation, coupled to electrospray ionization mass spectrometry with ion trap mass analyzer was applied for the analyses of CS-derived disaccharides. UPLC separation technology utilizes small particle diameter, short column length, and elevated column temperature to obtain high resolution and sensitivity. Hexylamine (15 mM) was selected the optimal ion-pairing reagent.

Solakyildirim, Kemal; Zhang, Zhenqing; Linhardt, Robert J.

2010-01-01

178

Purification of proteins containing zinc finger domains using Immobilized Metal Ion Affinity Chromatography  

PubMed Central

Heterologous proteins are frequently purified by Immobilized Metal Ion Affinity Chromatography (IMAC) based on their modification with a hexa-histidine affinity tag (His-tag). The terminal His-tag can, however, alter functional properties of the tagged protein. Numerous strategies for the tag removal have been developed including chemical treatment and insertion of protease target sequences in the protein sequence. Instead of using these approaches, we took an advantage of natural interaction of zinc finger domains with metal ions to purify functionally similar retroviral proteins from two different retroviruses. We found that these proteins exhibited significantly different affinities to the immobilized metal ions, despite that both contain the same type of zinc finger motif (i.e. CCHC). While zinc finger proteins may differ in biochemical properties, the multitude of IMAC platforms should allow relatively simple yet specific method for their isolation in native state.

Vorackova, Irena; Suchanova, Sarka; Ulbrich, Pavel; Diehl, William E.; Ruml, Tomas

2011-01-01

179

Size exclusion chromatography and viscometry in paper degradation studies. New Mark-Houwink coefficients for cellulose in cupri-ethylenediamine.  

PubMed

The paper deals with the application of size exclusion chromatography (SEC) for the studies of paper degradation phenomena. The goal is to solve some of the technical problems connected with the calibration of multi-detector SEC system and to find the correlation between SEC and viscometric results of degree of polymerization of cellulose. The results gathered for the paper samples degraded by acidic air pollutant (NO(2)) are used as an example of SEC-MALLS application. From the correlation between intrinsic viscosities and absolute value of molecular masses obtained with SEC/MALLS (Multi Angle Laser Light Scattering) technique, Mark-Houwink coefficients for cellulose in cupri-ethylenediamine solution were determined. Thus obtained coefficients were used for the determination of viscometric degree of polymerization (molecular mass) of the aged samples. An excellent correlation was found between the chromatographic values of molecular masses obtained with SEC-UV/VIS detection and the viscometric ones utilizing the improved values of Mark-Houwink coefficients. PMID:20833398

?ojewski, Tomasz; Zieba, Katarzyna; Lojewska, Joanna

2010-10-15

180

Online high-performance size exclusion chromatography-nuclear magnetic resonance for the characterization of dissolved organic matter.  

PubMed

The substantial heterogeneity of dissolved organic matter (DOM) inhibits detailed chromatographic analysis with conventional detectors as little structural information can be obtained in the presence of extensive coelution. Here we examine the direct hyphenation of high-performance size exclusion chromatography (HPSEC) with nuclear magnetic resonance (NMR) spectroscopy to determine how size-distinguished fractions differ in composition. The results support the applicability of using HPSEC to generate more homogeneous fractions of DOM prior to NMR analysis and demonstrate that structure is significantly altered with size. The largest fractions are enriched in carbohydrate- and aromatic-type structures. The midsized material is substantial and is representative of carboxyl-rich alicyclic molecules (CRAMs). The smallest material has strong signatures of material derived from linear terpenoids (MDLT). Both CRAMs and MDLT have been recently hypothesized as major components of DOM, and detection by HPSEC-NMR confirms their existence as unique and separable entities. This preliminary work focuses on NMR hyphenation to HPSEC due to widespread use of HPSEC to characterize DOM. Online hyphenation is useful not only for time-efficient analysis of DOM but also for that of other highly complex samples such as those found in many environmental analyses. PMID:20030309

Woods, Gwen C; Simpson, Myrna J; Kelleher, Brian P; McCaul, Margaret; Kingery, William L; Simpson, André J

2010-01-15

181

Size-exclusion high-performance liquid chromatography in the study of the autoassociating antibiotic gramicidin A in micellar milieu.  

PubMed

Gramicidin A (gA) is a polypeptide antibiotic which forms dimeric channels specific for monovalent cations in biological membranes. It is a polymorphic molecule that adopts several different conformations, double-stranded (ds) helical dimers (pore conformation) and single-stranded beta-helical dimers (channel conformation). This study investigated the conformational adaptability of gramicidin A when incorporated into micelles as membrane-mimetic model system. Taking advantage of our reported, versatile, size-exclusion high-performance liquid chromatography (SE-HPLC) strategy that allows the separation of double-stranded dimers and monomers, we have quantitatively characterized the conformational transition undergone by the peptide in the micellar milieu. The importance of both hydrophobic/hydrophilic moieties of the amphipaths in the stabilization of concrete conformational species is demonstrated using detergents with different hydrocarbon chain length and/or polar head. SE-HPLC is a valuable, rapid, accurate technique for the structural characterization of hydrophobic autoassociating peptides that work in lipid environments such as biological membranes. PMID:12834985

Bañó, Maria Carmen; Salom, David; Abad, Concepción

2003-06-30

182

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

SciTech Connect

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

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

1995-12-31

183

Kinetic effects on the interactions of Rh(III) with humic acids as determined using size-exclusion chromatography (SEC).  

PubMed

The anthropogenic inputs of Rh in the environment-together with other platinum group elements-have increased considerably during the last 20-30 years. However, thermodynamics and kinetics on the interaction of Rh with natural organic and inorganic ligands are still poorly characterized. Here, we report the time-dependent speciation of rhodium chlorides spiked to model freshwater with and without the presence of humic substances. Rhodium species were determined using size-exclusion chromatography-inductively coupled plasma mass spectrometry (SEC-ICP-MS). Results indicate that organic matter can effectively bind rhodium, but the extremely slow reaction kinetics of Rh plays a significant role on its speciation in natural waters. Accordingly, formation of Rh-organic complexes from spiked rhodium chlorides required around 15 days to reach equilibrium; this should be taken into account in those laboratory experiments where the biological interactions of Rh, using spiked samples, are studied. Regarding Rh inorganic speciation in freshwater, the available thermodynamic constants predict the dominance of the neutral trihydroxo and negatively charged tetrahydroxo rhodium complexes over typical pHs (6-8); our results, however, indicate only the presence of negatively charged hydroxocomplexes at pH 7. Reexamination of the Rh stability constants suggest that these hydroxylated rhodium complexes may also dominate its inorganic speciation in seawater. PMID:22875477

Cobelo-García, Antonio

2013-04-01

184

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

PubMed

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

Zhang, Qianqian; Kang, Jingwu

2013-07-01

185

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

USGS Publications Warehouse

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

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

1999-01-01

186

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

187

A novel size-exclusion high performance liquid chromatography (SE-HPLC) method for measuring degree of amylose retrogradation in rice starch  

Microsoft Academic Search

The objective of this study was to develop a new method to measure the degree of amylose retrogradation in rice starch using size-exclusion high performance liquid chromatography (SE-HPLC). This developed method is based on the change in molecule size related to the retention time of amylose. Results showed that SE-HPLC was able to provide accurate data to evaluate the amylose

Yaoqi Tian; Yin Li; Xueming Xu; Zhengyu Jin; Aiquan Jiao; Jinpeng Wang; Bo Yu

2010-01-01

188

Analysis of a complex polysaccharide (gum arabic) by multi-angle laser light scattering coupled on-line to size exclusion chromatography and flow field flow fractionation  

Microsoft Academic Search

The heterogeneous polysaccharide gum arabic has been characterized using size exclusion chromatography (SEC) and flow field flow fractionation (F4) coupled on-line to multi-angle laser light scattering (MALLS). Two distinct populations have been shown. About 80% of the material consist of highly branched arabinogalactan (AG) units. The rest is mainly composed of heterogeneous arabinogalactan–protein complex (AGP) of high molecular weight. The

L. Picton; I. Bataille; G. Muller

2000-01-01

189

Determination of pyrethroid pesticide residues in fatty materials by solid-matrix dispersion partition, followed by mini-column size-exclusion chromatography  

Microsoft Academic Search

The method studied uses a combination of a solid-matrix dispersion partition (SMDP) followed by high-performance size-exclusion chromatography on a minicolumn (HPmSEC) of 7.8 mm I.D. for the separation of pyrethroid (PYR) residues from fatty material. The solid-matrix dispersion extraction is carried out by absorbing a fat solution onto an Extrelut-3 cartridge (filled with a macroporous diatomaceous material) and extracting the

Alfonso Di Muccio; Patrizia Pelosi; Danilo Attard Barbini; Tiziana Generali; Silvana Girolimetti; Patrizia Stefanelli; Antonio Leonelli; Graziella Amendola; Luciano Vergori

1999-01-01

190

Rapid, quantitative determination of polar compounds in fats and oils by solid-phase extraction and size-exclusion chromatography using monostearin as internal standard  

Microsoft Academic Search

A rapid and simple method was developed for quantitation of polar compounds in fats and oils using monostearin as internal standard. Starting from 50 mg of oil sample, polar compounds were obtained by solid-phase extraction (silica cartridges) and subsequently separated by high-performance size-exclusion chromatography into triglyceride polymers, triglyceride dimers, oxidized triglyceride monomers, diglycerides, internal standard and fatty acids. Quantitation of

G. Márquez-Ruiz; N. Jorge; M. Martín-Polvillo; M. C. Dobarganes

1996-01-01

191

Functional speciation of metal-dissolved organic matter complexes by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry and deconvolution analysis  

NASA Astrophysics Data System (ADS)

High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry (HP-SEC-ICP-MS), in combination with deconvolution analysis, has been used to obtain multielemental qualitative and quantitative information about the distributions of metal complexes with different forms of natural dissolved organic matter (DOM). High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry chromatograms only provide continuous distributions of metals with respect to molecular masses, due to the high heterogeneity of dissolved organic matter, which consists of humic substances as well as biomolecules and other organic compounds. A functional speciation approach, based on the determination of the metals associated to different groups of homologous compounds, has been followed. Dissolved organic matter groups of homologous compounds are isolated from the aqueous samples under study and their high performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry elution profiles fitted to model Gaussian peaks, characterized by their respective retention times and peak widths. High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry chromatograms of the samples are deconvoluted with respect to these model Gaussian peaks. This methodology has been applied to the characterization of metal-dissolved organic matter complexes in compost leachates. The most significant groups of homologous compounds involved in the complexation of metals in the compost leachates studied have been hydrophobic acids (humic and fulvic acids) and low molecular mass hydrophilic compounds. The environmental significance of these compounds is related to the higher biodegradability of the low molecular mass hydrophilic compounds and the lower mobility of humic acids. In general, the hydrophilic compounds accounted for the complexation of around 50% of the leached metals, with variable contributions of humic and fulvic acids, depending on the nature of the samples and the metals.

Laborda, Francisco; Ruiz-Beguería, Sergio; Bolea, Eduardo; Castillo, Juan R.

2009-05-01

192

Simultaneous Cu, Fe, and Zn-specific detection of metalloproteins contained in rabbit plasma by size-exclusion chromatography–inductively coupled plasma atomic emission spectroscopy  

Microsoft Academic Search

Analytical methods which are capable of determining the plasma or serum metalloproteome have inherent diagnostic value for\\u000a human diseases associated with increased or decreased concentrations of specific plasma metalloproteins. We have therefore\\u000a systematically developed a method to rapidly determine the major Cu-, Fe-, and Zn-containing metalloproteins in rabbit plasma\\u000a (0.5 mL) based on size-exclusion chromatography (SEC; stationary phase Superdex 200, mobile

Shawn A. Manley; Simon Byrns; Andrew W. Lyon; Peter Brown; Jürgen Gailer

2009-01-01

193

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  

Microsoft Academic Search

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),

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

2005-01-01

194

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

PubMed

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

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

2008-12-12

195

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

PubMed

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

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

2013-04-10

196

Ionic composition of seawaters and derived saline solutions determined by ion chromatography and its relation to other water quality parameters  

Microsoft Academic Search

Ion chromatography (IC) presents new possibilities for assessing information about environmental samples, namely waters of various compositions, ranging from high-purity water to highly saline ones. Constant proportion between major ions present in seawater, has been assumed in the past, from which the first practical equation relating chlorinity and salinity has been developed, being later substituted by a practical salinity scale,

Nataša Gros; M. F. Camões; Cristina Oliveira; M. C. R. Silva

2008-01-01

197

Specific screening method for dextran and hydroxyethyl starch in human urine by size exclusion chromatography-in-source collision-induced dissociation-time-of-flight mass spectrometry.  

PubMed

The use of plasma volume expanders (PVE), such as dextran (DEX) and hydroxyethyl starch (HES), is prohibited in sports. DEX is a naturally occurring glucose polymer, whereas HES is synthetically produced from amylopectin starch by substitution with hydroxyethyl groups. In doping control, the commonly applied enzymatic and colorimetric screening methods are lacking adequate specificity for DEX and HES. Also, gas chromatographic-mass spectrometic (GC-MS) screening methods have specificity issues with DEX. In addition, due to the nature of the target compounds, time-consuming derivatisation steps are required in GC-MS. Based on the high molecular weight of carbohydrate polymers excreted in urine after administration of DEX and HES, a screening method was developed involving size exclusion chromatography (SEC) combined with time-of-flight mass spectrometry (TOFMS). By using solely a SEC guard column as an analytical column allowed sufficient chromatographic resolution in a minimal amount of time and with reasonable repeatability (average RSD of 10%). Detector response was linear throughout the measurement range with R(2)?>?0.99 for both analytes. Limits of detection were 100 and 250 ?g mL(-1) for DEX and HES, respectively. Ion suppression was found to be 52% at maximum. In-source collision-induced dissociation (ISCID) was used to produce characteristic fragments at a mass accuracy better than 2 mDa. The specificity of the SEC-ISCID-TOFMS method was demonstrated with 120 PVE negative doping control samples analyzed in parallel with a routine GC-MS screening method. In addition, seven urine samples from diabetic athletes, causing interpretation problems in routine GC-MS, showed here a definitely negative profile. PMID:21416163

Kolmonen, Marjo; Leinonen, Antti; Kuuranne, Tiia; Pelander, Anna; Deventer, Koen; Ojanperä, Ilkka

2011-08-01

198

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

PubMed

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

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

2013-04-01

199

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

PubMed Central

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

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

2013-01-01

200

Tailored Noise Waveform/ Collision-Induced Dissociation of Ions Stored in a Linear Ion Trap Combined with Liquid Chromatography/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

SciTech Connect

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

Vilkov, Andrey N.; Bogdanov, Bogdan; Pasa-Tolic, Liljiana; Prior, David C.; Anderson, Gordon A.; Masselon, Christophe D.; Moore, Ronald J.; Smith, Richard D.

2004-11-01

201

Indirect determination of cyanide compounds by ion chromatography with conductivity measurement  

SciTech Connect

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

Nonomura, M.

1987-09-01

202

Rapid determination of magnesium and calcium in water and serum by ion chromatography  

SciTech Connect

Single column ion chromatography was used to separate calcium and magnesium on poly(styrene-divinylbenzene) sulfonated to a capacity of 9 ..mu..eq/g. A 0.12 M HClO/sub 4/ eluent was used. The ions were complexed with Arsenazo I, at pH 10, in a post column reactor. The complexes were monitored spectrophotometrically at 590 nm. The separation of these ions is achieved in under three minutes. The method is rapid, reproducible, accurate and relatively free of interferences. A variety of water samples were analyzed and results agreed to within 10% with those obtained from an EDTA titration. Serum samples were analyzed for the total and ionized fractions of calcium and magnesium. For the total ion concentration, the serum was acidified, centrifuged and the liquid layer was injected into the chromatograph. The ionized forms of calcium and magnesium were separated, from the protein matrix, on a ''mini'' column filled with 0.07 g of XAD-4 resin sulfonated to a capacity of 2.8 meq/g. The ions were eluted from the ''mini'' 4 column with 4 M HCl, the mixture was buffered to pH 10 and injected into the chromatograph. A flow rate of 35 mL/min was required to push the serum sample through the ''mini'' column to prevent the equilibria of the bound fractions of calcium and magnesium from shifting.

Smith, D.L.

1987-08-01

203

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

PubMed

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

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

2013-05-21

204

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

PubMed

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 13kg 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?L of water per minute is lost to waste while operating standard-bore chromatography at 0.5mLmin(-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 15min using a low backpressure guard column with ?25mM 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?gL(-1)). Field analyses are shown for multiple on-site analyses of stream water indifferent weather conditions. PMID:24913366

Elkin, Kyle R

2014-07-25

205

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

SciTech Connect

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.

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

1996-06-01

206

[Nano-electrospray ionization-ion mobility spectrometry and its combination with high performance liquid chromatography].  

PubMed

A nano-electrospray ionization-ion mobility spectrometer (nanoESI-IMS) was built up. Firstly, the effects of the parameters such as drift gas flow rate and solvent flow rate on the desolvation capability were studied and optimized. Then, a series of compounds were used to characterize the nanoESI-IMS system. The results showed that, complete desolvation was achieved for nano-electrospray ion droplets with the nanoESI-IMS apparatus. The limit of detection of this instrument for trioctylamine could reach 10 microg/L. Finally, this instrument was coupled to the high performance liquid chromatography (HPLC) as a detector for amines analysis. A test mixture containing triethylamine, diethylamine and butylamine was successfully separated and determined by the HPLC-nanoESI-IMS system. Linear response ranges of about two orders of magnitude were achieved for triethylamine, diethylamine and butylamine with this system. PMID:23898640

Chen, Chuang; Wang, Weiguo; Liang, Xixi; Zhou, Qinghu; Peng, Liying; Wen, Meng; Ju, Bangyu; Zhao, Kun; Liu, Jun; Li, Haiyang

2013-04-01

207

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

208

Comparison of diafiltration and size-exclusion chromatography to recover hemicelluloses from process water from thermomechanical pulping of spruce.  

PubMed

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. PMID:18478449

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

2007-04-01

209

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

NASA Astrophysics Data System (ADS)

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

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

210

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

PubMed

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

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

2010-01-01

211

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

PubMed Central

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

Hofmann, Christina L.; Smith, Ross; Chen, Michelle H.

2010-01-01

212

Purification of dye-labeled oligonucleotides by ion-pair reversed-phase high-performance liquid chromatography  

Microsoft Academic Search

Singly- and dually-labeled synthetic oligonucleotides were purified by ion-pair reversed-phase high-performance liquid chromatography using a 50×4.6-mm column packed with porous, 2.5 ?m C18 sorbent. We studied the mechanism of dye-labeled oligonucleotide retention in order to improve the quality of purification. By-products of oligonucleotide synthesis were characterized by liquid chromatography with mass spectrometry detection (LC–MS). We purified oligonucleotides labeled with 6-carboxyfluorescein

Kenneth J. Fountain; Martin Gilar; Yeva Budman; John C. Gebler

2003-01-01

213

Identification of Human Liver Diacetyl Reductases by Nano-Liquid Chromatography\\/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

Microsoft Academic Search

Several forms of diacetyl-reducing enzyme were found to exist in the human liver cytosol. Three (DAR-2, DAR-5, and DAR-7) of them were purified as a single band on SDS–PAGE by a combination of a few kinds of column chromatographies. The in-gel tryptic digests of the purified enzymes were analyzed by nano-liquid chromatography (LC)\\/Fourier transform ion cyclotron resonance mass spectrometry (FT

Yorihisa Tanaka; Ikuya Sato; Chisaki Iwai; Toshiyuki Kosaka; Toshihiko Ikeda; Takemichi Nakamura

2001-01-01

214

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

PubMed Central

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

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

2011-01-01

215

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

PubMed

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

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

2012-11-01

216

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

PubMed

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

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

2014-05-01

217

Quantification of cholesterol tracers by gas chromatography--negative ion chemical ionization mass spectrometry.  

PubMed

Because of its high sensitivity, gas chromatography negative ion chemical ionization mass spectrometry (GC-NCI-MS) is a potentially valuable analytical tool for the study of cholesterol metabolism. Of several derivatives prepared for potential use in tracer studies pentafluorobenzoyl cholesterol was selected because it formed rapidly at ambient temperature and was stable for long periods, could be detected at a level of 1 fmol, and yielded a mass spectrum in which the molecular ion was the principal component. Hexadeuterated cholesterol tracer ([26,26,26,27,27,27-2H6]cholesterol) could be detected in dilutions up to 2700 in unlabeled cholesterol by selected ion monitoring with a coefficient of variation averaging 3.2%. In seven normal subjects tracer cholesterol was infused intravenously and plasma cholesterol enrichment was determined after 4 h. The measured rapidly miscible cholesterol pool was 391.0 +/- 38.6 mg cholesterol/kg. Negative ion mass spectrometry of pentafluorobenzyol cholesterol will facilitate analysis of both small amounts of natural cholesterol and labeled cholesterol in applications where sensitivity is critical. PMID:8946736

Ostlund, R E; Hsu, F F; Bosner, M S; Stenson, W F; Hachey, D L

1996-11-01

218

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

PubMed

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

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

2009-09-18

219

Evaluation of the thermal effect on separation selectivity in anion-exchange processes using superheated water ion-exchange chromatography.  

PubMed

The thermal effect on retention and separation selectivity of inorganic anions and aromatic sulfonate ions in anion-exchange chromatography is studied on a quaternized styrene-divinylbenzene copolymer anion-exchange column in the temperature range of 40-120 °C using superheated water chromatography. The selectivity coefficient for a pair of identically charged anions approaches unity as temperature increases provided the ions have the same effective size, such that the retention of an analyte ion decreases with an increase in temperature when the analyte ion has stronger affinity for the ion-exchanger than that of the eluent counterion, whereas it increases when it has weaker affinity. The change in anion-exchange selectivity with temperature observed with superheated water chromatography has been discussed on the basis of the effect of temperature on hydration of the ions. At elevated temperatures, especially in superheated water, the electrostatic interaction or association of the ions with the fixed ion in the resin phase becomes a predominant factor resulting in a different separation selectivity from that obtained at ambient temperature. PMID:22614168

Shibukawa, Masami; Taguchi, Akihiko; Suzuki, Yusuke; Saitoh, Kazunori; Hiaki, Toshihiko; Yarita, Takashi

2012-07-01

220

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

PubMed

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

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

2013-03-01

221

Complexation ion-exchange chromatography of some metal ions on papers impregnated with Ti(IV)-based inorganic ion exchangers.  

PubMed

The chromatographic behavior of 40 metal ions is studied on titanium (IV) arsenate, titanium (IV) phosphate-, titanium (IV) molybdate-, titanium(IV) tungstate-, and titanium(IV) selenite-impregnated papers in 0.1M oxalic, citric, and tartaric acid as mobile phases. Similar studies are carried out on Whatman No. 1 papers for comparison. The ion-exchange capacity of these papers is determined, and their selectivity for different cations is discussed. The mechanism of migration is explained in terms of ion-exchange, precipitation, and adsorption. The prediction of elution sequence from RF values is also checked. The average Ri is found to be almost linearly dependent on the charge of the metal ions. The effect of the pKa of complexing acids on average RF values of 3d series metal ions is explained. A number of binary and ternary separations are achieved. PMID:10677834

Sharma, S D; Gupta, R

2000-02-01

222

High-speed and high-performance size-exclusion chromatography of proteins on a new hydrophilic polystyrene-based resin.  

PubMed

High-performance size-exclusion chromatography of some standard proteins, peptides and amino acids on a new hydrophilic packing material obtained by chemical transformation of a cross-linked polystyrene-divinylbenzene copolymer was studied. Columns filled with 4 and 7 micron particles were compared. The influence of the concentration of acetonitrile, isopropanol and trifluoroacetic acid in the mobile phase on the chromatographic performance was investigated. A good linear calibration graph covering the molecular weight range from 200 to 700,000, was obtained under the optimal conditions. The packing material can be used for separations, for molecular weight determinations and for the pre-fractionation of proteins. The high rigidity of the packing material allows relatively high pressures to be used and therefore fast separations to be achieved. The packing material was applied to the chromatography of proteins from beer, bones and milk. PMID:3584334

Yang, Y B; Verzele, M

1987-04-01

223

Determination of the triple helical chain conformation of ?-glucan by facile and reliable triple-detector size exclusion chromatography.  

PubMed

Triple helical polysaccharides (t-polysaccharides) are easily gelated in water, resulting in difficult fractionation, leading to the complex and time-consuming chain conformational characterization. Moreover, the fractionation is not always successful due to the coexistence of individual chains and aggregates. In this work, we developed a facile and reliable method to rapidly and accurately characterize the chain conformation of t-polysaccharide without fractionation needed in traditional conformation characterization. A triple helical ?-1,3-glucan (t-?-1,3-glucan), extracted from the fruiting bodies of Lentinus edodes, was identified to consist of a ?-1,3-glucan with two ?-1,6-D-glucopyranoside branchings for every five ?-1,3-glucopyranoside linear linkages by one- and two-dimensional NMR and GC-MS analysis. The chain conformations of the t-?-glucan in aqueous solution and in DMSO were successfully characterized by a combination of size exclusion chromatography (SEC), multiangle static light scattering, a differential refractometer, and a capillary viscosity detector (triple-detector SEC). The results revealed that the predominate species of the t-?-glucan in a 0.15 M NaCl aqueous solution existed as a triple helical conformation with high chain stiffness, and a few aggregates (4%) coexisted here. The Mark-Houwink and ?S(2)?(1/2) versus M(w) equations of individual triple helical chains and aggregates were obtained simultaneously, and the results confirmed again the coexistence of two kinds of chain conformations. The fractal dimension indicated that the aggregate in the aqueous solution was a kind of reversible microgel with a 3D network structure. Furthermore, the chain morphology of the t-?-glucan in aqueous solution was observed directly by transmission electron microscopy and atomic force microscopy to support the worm-like chain for the individuals and 3D network for the aggregates. The triple-detector SEC technology was facile and reliable for the system with two fractions of different chain conformation, and the test time required was only 1/30 of what the traditional method needed. PMID:24400948

Li, Sheng; Huang, Yao; Wang, Sen; Xu, Xiaojuan; Zhang, Lina

2014-01-23

224

Polydispersity characterization of lipid nanoparticles for siRNA delivery using multiple detection size-exclusion chromatography.  

PubMed

The development of lipid nanoparticle (LNP) based small interfering RNA (siRNA) therapeutics presents unique pharmaceutical and regulatory challenges. In contrast to small molecule drugs that are highly pure and well-defined, LNP drug products can exhibit heterogeneity in size, composition, surface property, or morphology. The potential for batch heterogeneity introduces a complexity that must be confronted in order to successfully develop and ensure quality in LNP pharmaceuticals. Currently, there is a lack of scientific knowledge in the heterogeneity of LNPs as well as high-resolution techniques that permit this evaluation. This article reports a size-exclusion chromatography (SEC) method that permits the high-resolution analysis of LNP size distribution in its native solution condition. When coupled with multiple detection systems including UV-vis, multi-angle light scattering, and refractive index, on-line characterization of the distributions in size, molecular weight, and siRNA cargo loading of LNPs could be achieved. Six LNPs with sizes in the rang of 60-140 nm were evaluated and it was found that the SEC separation is efficient, highly reproducible, and can be broadly applied to a diverse range of LNPs. A comparison between the current SEC method and asymmetric field flow fractionation (FFF) shows that the current method provides similar size distribution results on LNPs compared to FFF. Two representative LNPs with similar bulk properties were evaluated in-depth using the SEC method along with two other sizing techniques-dynamic light scattering and cryo-TEM. Profound differences in batch polydispersity were observed between them. Despite the similarity in the particle assembly process, it was found that one LNP (A) possessed a narrow size and molecular weight distribution while the other (B) was polydisperse. The present results suggest that LNP drug products are highly complex and diverse in nature, and care should be taken in examining and understanding them to ensure quality and consistency. The method developed here can not only serve as a method for understanding LNP product property, permitting control on product quality, but also could serve as a potential manufacturing method for product purification. Understandings obtained in this work can help to facilitate the development of LNPs as a well-defined pharmaceutical product. PMID:22816783

Zhang, Jingtao; Haas, R Matthew; Leone, Anthony M

2012-07-17

225

Unfolding of a model protein on ion exchange and mixed mode chromatography surfaces.  

PubMed

Recent studies with proteins indicate that conformational changes and aggregation can occur during ion exchange chromatography (IEC). Such behavior is not usually expected, but could lead to decreased yield and product degradation from both IEC and multi mode chromatography (MMC) that has ligands of both hydrophobic and charged functionalities. In this study, we used hydrogen exchange mass spectrometry to investigate unfolding of the model protein BSA on IEC and MMC surfaces under different solution conditions at 25°C. Increased solvent exposure, indicating greater unfolding relative to that in solution, was found for protein adsorbed on cationic IEC and MMC surfaces in the pH range of 3.0 to 4.5, where BSA has decreased stability in solution. There was no effect of anionic surfaces at pH values in the range from 6.0 to 9.0. Differences of solvent exposure of whole molecules when adsorbed and in solution suggest that adsorbed BSA unfolds at lower pH values and may show aggregation, depending upon pH and the surface type. Measurements on digested peptides showed that classifications of stability can be made for various regions; these are generally retained as pH is changed. When salt was added to MMC systems, where electrostatic interactions would be minimized, less solvent exposure was seen, implying that it is the cationic moieties, rather than the hydrophobic ligands, which cause greater surface unfolding at low salt concentrations. These results suggest that proteins of lower stability may exhibit unfolding and aggregation during IEC and MMC separations, as they can with hydrophobic interaction chromatography. PMID:24997510

Gospodarek, Adrian M; Hiser, Diana E; O'Connell, John P; Fernandez, Erik J

2014-08-15

226

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

Microsoft Academic Search

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

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

227

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

PubMed

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

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

2005-04-15

228

Analysis of carbohydrates and amino acids in vegetable waste waters by ion chromatography.  

PubMed

High-performance anion exchange chromatography coupled with pulsed amperometric detection was used for the quantitative determination of total and free sugars in olive oil mill waste waters (OMWW). Automated amino acid ion chromatography was employed to analyse total and free amino acids in the same OMWW. Sugars were analysed in samples pre-purified by means of a three-step purification procedure involving: (i) methanol precipitation of OMWW; (ii) dialysis of the obtained solid and liquid fractions; and (iii) chromatographic purification on RP18 phase followed by Amberlite resin. The amino acids were determined directly in samples obtained from the first two steps performed for sugar analysis. The analysis carried out with the reported methodologies allowed the quantitative determination of total sugars and amino acids and the differentiation between their free and bound forms. The sugars determined were arabinose, fructose, galactose, glucose, rhamnose, xylose, galacturonic and glucuronic acids, and the amino acids were Asp, Glu, Thr, Ser, Pro, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe, Lys, His, Arg and Cys. Asn, Gin, and Trp were not detected. The technological, biotechnological and environmental advantages arising from this analytical methodology applied to OMWW are briefly discussed. PMID:12693630

Arienzo, Michele; De Martino, Antonio; Capasso, Renato; Di Maro, Antimo; Parente, Augusto

2003-01-01

229

Diagnosis of porphyrias by ion-pair high-performance liquid chromatography.  

PubMed

Ion-pair reversed-phase high-performance liquid chromatography together with fluorescence detection is useful in the analysis of urinary porphyrin carboxylic acids. The sensitive and quantitative detection facilitates the clinical diagnosis of porphyrias. The method described permits the detection of porphyrins down to 0.1 ng directly from urine without laborious sample pre-treatment. A linear response curve was obtained from 0.2 up to 200 ng for coproporphyrin I. The within-assay correlation coefficients ranged from 2.5 to 10.1%. Recovery experiments gave an accuracy of 89-109%. The rapidity and simplicity of the method allows its application to the routine analysis of urinary porphyrins in the clinical laboratory. PMID:7451603

Meyer, H D; Jacob, K; Vogt, W; Knedel, M

1980-10-31

230

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

SciTech Connect

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.

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

231

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

PubMed

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

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

2011-02-01

232

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

PubMed

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

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

2013-03-15

233

Determination of chloroacetic acids in drinking water using suppressed ion chromatography with solid-phase extraction.  

PubMed

Suppressed ion chromatography with a conductivity detector was developed for the determination of trace amounts of underivatized chloroacetic acids (CAAs). When sodium carbonate and methanol were used as a mobile phase, the simultaneous determination of each CAA took approximately 25 min. The linearity, reproducibility and detection limits were determined for the proposed method. For the solid-phase extraction step, the effects of the pH of the sample solution, sample volume and the eluting agent were tested. Under the optimized extracting conditions, the average recoveries for CAAs spiked in tap water were 83-107%, with an optimal preconcentration factor of 20. The reproducibility of recovery rate for CAAs was 1.2-3.8%, based upon 6 repetitions of the recovery experiments. PMID:20009341

Yoshikawa, Kenji; Soda, Yuko; Sakuragawa, Akio

2009-12-01

234

Determination of bisphosphonates by ion chromatography-inductively coupled plasma mass spectrometry.  

PubMed

An ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) was introduced in the analysis of bisphosphonates. Two compounds (alendronic acid and etidronic acid) were separated on a Dionex AS-7 anion-exchange column with dilute nitric acid employed as the mobile phase. The analytes were detected at m/z 31, as they contain phosphorus. The detection limits achieved were 0.20 mg l(-1) for alendronic acid and 0.05 mg l(-1) for etidronic acid. Since the determination of phosphorus by ICP-MS is difficult due to polyatomic interferences at m/z 31 (15N16O+, 14N16O1H+, and 12C1H(3)16O+), a detailed study of the influence of plasma parameters on phosphorus and background signal was performed. PMID:15250406

Kovacevic, Miroslav; Gartner, Andrej; Novic, Milko

2004-06-11

235

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

236

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

PubMed

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

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

2013-03-01

237

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

SciTech Connect

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

Wiedenman, B.; White, T.

2009-11-16

238

Scaled-up separation of cellobiohydrolase1 from a cellulase mixture by ion-exchange chromatography.  

PubMed

Enzymatic hydrolysis of cellulose often involves cellulases produced by Trichoderma reesei, of which cellobiohydrolase1 (CBH1) is the most abundant (about 60% of total cellulases) and plays an important role in the hydrolysis of crystalline cellulose. A method for separating sufficient quantities from the bulk cellulase cocktail is highly desirable for many studies, such as those that aim to characterize binding and hydrolysis kinetics of CBH1. In this work, CBH1 was separated from other Spezyme CP cellulases by ion-exchange chromatography using an efficient modification of a smaller scale process. The ion-exchange column was connected to a vacuum manifold system to provide a steady flow through parallel columns and thus achieve scale-up for enzyme separation. With five 5-mL columns running in parallel, about 55 mg of CBH1 was separated from 145 mg of Spezyme CP in a single separation. Step elution was used to replace the continuous gradient used at smaller scale. The purified CBH1 was collected in the fraction eluted with a buffer containing 0.33 M salt and showed comparable purity and activity as the enzyme purified by a fast protein liquid chromatography system. The stability of separated CBH1 was studied for up to 2 days and good thermal stability was observed. Separated CBH1 also showed both high adsorption to bacterial microcrystalline cellulose with ~4 ?mol/g maximum adsorption and a K(a) of 5.55 ± 2.34 ?M(-1) , and good hydrolytic activity based on atomic force microscopy observations that show a reduction in fiber height. PMID:21905272

Ye, Zhuoliang; Lane, Andrew N; Willing, Gerold A; Berson, R Eric

2011-01-01

239

Determination of total sulfur by ion chromatography following peroxide oxidation in spent caustic from the chemical cleaning of coal  

Microsoft Academic Search

Total sulfur in samples of spent caustic arising from the chemical cleaning of coal has been determined by ion chromatography after oxidation of all sulfur species to sulfate. Oxidation with hydrogen peroxide first under basic conditions and subsequently under strongly acidic conditions was required for quantitative conversion of all sulfur species to sulfate. The effects of pH, sample size, and

Colin D. Chriswell; David R. Mroch; Richard. Markuszewski

1986-01-01

240

Determination of organic acids in the presence of inorganic anions by ion chromatography with suppressed conductivity detection  

Microsoft Academic Search

Simultaneous separation of 19 organic acids and 10 inorganic anions has been demonstrated using ion chromatography with a high capacity anion exchange column and the suppressed conductivity detector under an auto-suppression external sulfuric acid mode. Quantitative merits of this method were examined for analysis of nine organic acids of potential significance in cell culture broth. External calibration curves for these

Xiumei Geng; Sufang Zhang; Qian Wang

2008-01-01

241

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...

242

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

ERIC Educational Resources Information Center

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

Drossman, Howard

2007-01-01

243

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

SciTech Connect

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

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

2011-05-30

244

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...

245

Determination of 1-aminocyclopropane-1-carboxylic acid and its structural analogue by liquid chromatography and ion spray tandem mass spectrometry.  

PubMed

Liquid chromatography coupled to ion spray tandem mass spectrometry was developed as a method for the simultaneous analysis of the amino acid 1-aminocyclopropane-1-carboxylic acid (ACC) and its structural analogue, cyclopropane-1,1-dicarboxylic acid (CDA). ACC and CDA fragmentation as well as optimization of MS parameters were investigated in positive ion mode. In selective reaction monitoring mode the protonated molecule [M+H]+ was selected as parent ion for both ACC and CDA, while the immonium ion from ACC and the [M+H-H2O]+ ion from CDA were selected, respectively, as product ions. In spite of the high selectivity of MS/MS among the 20 protein amino acids potentially present with ACC and CDA in the plant material analyzed, Glu and Thr can interfere with the signal of ACC. As a result, their chromatographic separation is necessary. This was achieved in less than 4 min by ion-pair reversed-phase chromatography with nonafluoropentanoic acid as ion-pair reagent. A linear response within a concentration range of 1-5 mg l(-1) was observed for this LC method and the detection limit was found to be 20 pmol for ACC and 150 pmol for CDA (using a 20-microl loop). This methodology was successfully applied to the detection of ACC in apple tissue. PMID:11093668

Petritis, K; Dourtoglou, V; Elfakir, C; Dreux, M

2000-10-27

246

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

PubMed

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

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

2013-12-01

247

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

PubMed

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

Döker, Serhat; Mounicou, Sandra; Do?an, Mehmet; Lobinski, Ryszard

2010-08-01

248

Evaluation and comparison of commercially available Aloe vera L. products using size exclusion chromatography with refractive index and multi-angle laser light scattering detection.  

PubMed

Raw materials supplied as Aloe vera L. (sometimes referred to as Aloe barbadensis) samples often contain different composition of low and high molecular weight components when analyzed by size exclusion chromatography. One major reason for variable compositions of commercial A. vera L. materials is that they are produced by different manufacturing techniques. Consistent composition of matter based upon a given standard has been difficult to define. In addition, the method of quantifying and characterization of these commercially available materials has not been agreed upon within the industry. The end user, whether a researcher, a manufacturer, a marketing arm of industry or the consumer, should know that they are receiving a consistent product. A blind study of 32 various A. vera L. samples from different manufacturers, and a prepared sample of fresh A. vera L. gel with the commercial, biologic drug Acemannan Immunostimulanttrade mark, were analyzed for content of high molecular weight (polysaccharides) material by size exclusion chromatography with refractive index detection (SEC/RI) and SEC/RI coupled with multi-angle laser light scattering (MALLS) detection. Results from the SEC/RI analysis showed significant variation in the high molecular weight content, and the MALLS analysis also showed significant variation versus SEC/RI. In addition, HPLC analysis of the anthraquinone content showed that all samples contained significantly less than that of the raw, unwashed aloe gel. The variation of results from all analysis is attributed to differing methods in which the samples were processed by the different manufacturers. PMID:15531289

Turner, Carlton E; Williamson, David A; Stroud, Paul A; Talley, Doug J

2004-12-20

249

[Determination of trace haloacetic acids in drinking water using ion chromatography coupled with solid phase extraction].  

PubMed

The combined solid phase extraction (SPE)-ion chromatography (IC) method was developed for the analysis of trace haloacetic acids (HAAs) in drinking water. The tested HAAs included monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), monobromoacetic acid (MBAA) and dibromoacetic acid (DBAA). For trace determination of HAAs in real drinking water samples, conditions of LiChrolut EN SPE cartridge were investigated for HAAs preconcentration and matrix elimination. Elution was carried out by 2 mL of sodium hydroxide (10 mmol/L) with the flow rate of 2 mL/min. The Dionex IonPac AS16 column (250 mm x 4 mm i. d.), a high capacity and hydroxide-selective anion-exchange column designed for the determination of polarizable anions, was chosen for chromatographic separation. HAAs were analyzed with a concentration gradient of NaOH with the flow rate of 0.8 mL/min and detected by suppressed conductivity. A 500 microL sample loop was used. The detection limits of this SPE-IC method for MCAA, DCAA, DBAA and TCAA were 0.38-1.69 microg/L and MBAA was 12.5 microg/L under 25-fold preconcentration. The results demonstrate that the method is suitable for the analysis of trace haloacetic acids in drinking water. PMID:16929853

Sun, Yingxue; Huang, Jianjun; Gu, Ping

2006-05-01

250

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

PubMed

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

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

2011-03-01

251

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

PubMed

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

Fauland, Alexander; Köfeler, Harald; Trötzmüller, Martin; Knopf, Astrid; Hartler, Jürgen; Eberl, Anita; Chitraju, Chandramohan; Lankmayr, Ernst; Spener, Friedrich

2011-12-01

252

Simultaneous quantitative analysis of metabolites using ion-pair liquid chromatography-electrospray ionization mass spectrometry.  

PubMed

We have developed an analytical method, consisting of ion-pair liquid chromatography coupled to electrospray ionization mass spectrometry (IP-LC-ESI-MS), for the simultaneous quantitative analysis of several key classes of polar metabolites, like nucleotides, coenzyme A esters, sugar nucleotides, and sugar bisphosphates. The use of the ion-pair agent hexylamine and optimization of the pH of the mobile phases were critical parameters in obtaining good retention and peak shapes of many of the above-mentioned polar and acidic metabolites that are impossible to analyze using standard reversed-phase LC/MS. Optimum conditions were found when using a gradient from 5 mM hexylamine in water (pH 6.3) to 90% methanol/10% 10 mM ammonium acetate (pH 8.5). The IP-LC-ESI-MS method was extensively validated by determining the linearity (R2 > 0.995), sensitivity (limit of detection 0.1-1 ng), repeatability, and reproducibility (relative standard deviation <10%). The IP-LC-ESI-MS method was shown to be a useful tool for microbial metabolomics, i.e., the comprehensive quantitative analysis of metabolites in extracts of microorganisms, and for the determination of the energy charge, i.e., the cellular energy status, as an overall quality measure for the sample workup and analytical protocols. PMID:16970336

Coulier, Leon; Bas, Richard; Jespersen, Sonja; Verheij, Elwin; van der Werf, Mariët J; Hankemeier, Thomas

2006-09-15

253

Purification of tubulin and microtubule-associated proteins by membrane ion-exchange chromatography.  

PubMed

Microtubules, composed of tubulin and microtubule-associated proteins (MAPs), can be isolated using routine procedures from homogenates of vertebrate brain. Often, it is necessary then to purify the tubulin from the MAPs, and normally this purification is effected by standard techniques of ion-exchange chromatography. However, such procedures can be expensive, both in the consumption of buffers and other expensive components (e. g. GTP) and in investigator time. Here, we demonstrate that membrane ion exchangers mounted in syringe filter cartridges can be used to separate tubulin from MAPs in a matter of minutes, compared to the several hours that are normally required for typical chromatographic procedures using phosphocellulose orDEAE. The resulting tubulin is competent to assemble into microtubules upon either addition of the purified MAPs or addition of the microtubule-stabilizing drug Taxol. Thus, the procedure should be useful to investigators requiring a rapid and effective purification of tubulin for use in assembly studies or in vitro motility assays. PMID:9675064

Sloboda, R D; Belfi, L M

1998-07-01

254

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

PubMed

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

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

2014-05-30

255

Specific determination of bromate in bread by ion chromatography with ICP-MS.  

PubMed

A sensitive method for detecting bromate in bread by ion chromatography with inductively-coupled plasma mass spectrometry (IC/ICP-MS) was developed. Bromate was extracted from bread with water. The clean-up procedure included a 0.2 micron filter, a C18 cartridge for defatting, a silver cartridge to remove halogen anions, a centrifugal ultrafiltration unit to remove proteins, and a cation-exchange cartridge to remove silver ions. A 500 microL sample solution was applied to IC/ICP-MS. The detection limit and the quantitation limit of bromate in the solution were 0.3 ng/mL and 1.0 ng/mL, expressed as HBrO3, respectively, which corresponded to 2 ng/g and 5 ng/g, respectively, in bread. Recovery of bromate was about 90%, and the CV was about 2%. Based on the detection limit in solution and recovery from bread, the detection limit of bromate in bread was estimated to be 2 ng/g. PMID:12635336

Akiyama, Takumi; Yamanaka, Michiko; Date, Yukiko; Kubota, Hiroki; Nagaoka, Megumi Hamano; Kawasaki, Yoko; Yamazaki, Takeshi; Yomota, Chikako; Maitani, Tamio

2002-12-01

256

Determination of salsolinol by ion-exchange chromatography with glycylglycine as the post-derivatizing agent.  

PubMed

The determination of salsolinol in human urine was carried out by ion-exchange chromatography on two coupled columns of a weakly acidic ion exchanger with a hydrophilic matrix (Asahipak ES-502C). Salsolinol was first isolated from urine by adsorption on Amberlite CG-50. It was eluted together with catecholamines by 2/3 M boric acid solution. The amines were then separated by isocratic elution from the first column of Asahipak with 0.05 M sodium succinate buffer (pH 5.5) containing 0.015 M borate and 0.5 mM ethylenediaminetetraacetate. Epinephrine, norepinephrine, dopamine and salsolinol were eluted in that order. The salsolinol-containing fraction was then transferred, by column switching, to a second Asahipak column and eluted with the same mobile phase. Salsolinol was determined fluorimetrically by reaction with glycylglycine in the presence of hexacyanoferrate(III) at pH 7.5-8 and 65 degrees C. Samples could be analysed every 47 min. The detection limit for salsolinol was 2 pmol/ml. PMID:3243899

Seki, T; Yanagihara, Y; Noguchi, K

1988-12-28

257

Determination of cannabinoids in cannabis products using liquid chromatography-ion trap mass spectrometry.  

PubMed

A method was developed and validated for the simultaneous determination of five cannabinoids, viz. cannabidiol (CBD), cannabidiol acid (CBD-COOH), cannabinol (CBN), delta9-tetrahydrocannabinol (THC), and 3'-carboxy-delta9-all-trans-tetrahydrocannabinol (THC-COOH) in cannabis products. The cannabinoids were extracted from the grinded cannabis samples with a mixture of methanol-chloroform and analysed using liquid chromatography with ion-trap-mass-spectrometry (LC-IT-MSn). For quantification the two most abundant diagnostic MS-MS ions of the analyte in the sample and external standard were monitored. For confirmation purposes the EU criteria as described in Commission Decision 2002/657/EC were followed. Fully satisfactory results were obtained, that is, unequivocal confirmation according to the most stringent EU criteria was possible. The limits of quantification were 0.1 g/kg for CBD, 0.04 g/kg for CBD-COOH, 0.03 g/kg for CBN, 0.28 g/kg for THC and 9.9 g/kg for THC-COOH. The repeatabilities, defined by R.S.D., were 2% for CBN, THC and THC-COOH at the concentration levels of respectively 0.023, 3.3 and 113 g/kg and 5% for CBD-COOH at the level of 0.34 g/kg (n = 6). PMID:15595662

Stolker, A A M; van Schoonhoven, J; de Vries, A J; Bobeldijk-Pastorova, I; Vaes, W H J; van den Berg, R

2004-11-26

258

Purification of hemoglobin by ion exchange chromatography in flow-through mode with PEG as an escort.  

PubMed

Development of hemoglobin-based blood substitutes requires production of highly purified hemoglobin. Process of hemoglobin purification by ion exchange chromatography in flow-through mode was researched and optimized. Three kinds of media including, QMA Spherosil LS (Biosepra, France) and Q Sepharose Big Beads (Amersham Bioscience, Sweden), and an anion exchange membrane column, Mustang Q (PALL, USA) were investigated and compared. Adding polyethylene glycol (PEG) as an escort in ion exchange chromatography improved the purity and recovery, and the recovery in the chromatography was increased from 75 to 95%. The mechanism of PEG effects on chromatography was discussed. The optimal chromatography step, in combination with hypotonic dilution hemolyzing and membrane separation, formed an integrated hemoglobin purification process. The total recovery in the process was 87.6%. The activity of hemoglobin was well preserved: P50 23.2 mmHg, and Hill coefficient 2.31. The product appeared as a single band in SDS-PAGE, and GF-HPLC showed only one peak. The purity of the prepared hemoglobin was more than 99.9%. The optimized process is time saving and suitable for large-scale preparation of hemoglobin to provide materials for further preparation of blood substitutes. PMID:15274429

Lu, Xiuling; Zhao, Dongxu; Su, Zhiguo

2004-05-01

259

Effects of ion exclusion and isotopic fractionation on pore water geochemistry during gas hydrate formation and decomposition  

Microsoft Academic Search

The effects of ion exclusion and isotopic fractionation associated with gas hydrate formation and decomposition in continental margin sediments are examined using simple mass balance calculations. In a closed system pore fluid salinity can be increased to brine levels and detectable changes in interstitial waterd18O can be caused by formation of significant amounts of interstitial gas hydrate. Time- and mass-dependent

W. Ussler; C. K. Paull

1995-01-01

260

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

PubMed

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

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

2011-06-01

261

Chromatography Theory  

NSDL National Science Digital Library

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

2011-05-26

262

Bacterial sulfate production by biodesulfurization of aromatic hydrocarbons, determined by ion chromatography.  

PubMed

The use of bacteria to remove sulfur from crude oil or petroleum distillates is a novel concept that presents an alternative biotechnology to the current technology of hydrodesulfurization (HDS). Sulfur must be removed from crude oils prior use. The burning of fossil fuels containing sulfur releases sulfur dioxide into the atmosphere causing acid rain. The aim of this work is to determine the sulfate concentration by ion chromatography (IC), and calculate the percentage of transformation of organic bound sulfur, that is converted to sulfate, and estimate the efficiency of bacteria in desulfurization. IC is a suitable method for sulfate concentration determination. However, when chloride concentrations are significantly high, interference of the sulfate signal does occur. In this case, it could be avoided by diluting samples. A Dionex Model 2000i/SP IC system, with an anionic pre-column (Dionex AG4A), an anion separator column (Dionex AS4A), a suppressor column (Dionex AMMS-II), and a conductivity detector was used. The eluent (21 mM NaOH) and regenerant (electrolyzed 18 M omega/cm water) flow-rates were 1.0 and 2.0 ml/min, respectively. The sample loop volume was 10 microliters and the conductivity sensitivity was 30 muS. The diluted samples were filtered through a 0.45-micron filter before injection. The highest sulfate concentration detected was 24.10 mg/l, corresponding to a maximal conversion rate of 10% in a month. Sulfate ions were not detected in control samples. The correlation coefficient for a linear least squares fit was 0.99 (p < 0.001). The minimal concentration that we can read was 0.02 mg/l and this concentration corresponded to the limit of detection obtained under the conditions employed in this study. IC is an economical, sensitive and accurate way to estimate the sulfate concentrations in microbiological samples. PMID:9818427

Soto, L M; Ledo, H; Calderón, Y; Marín, J; Galarraga, F

1998-10-16

263

Determination of haloacetic acids in hospital effluent after chlorination by ion chromatography.  

PubMed

The ion chromatography combined solid phase extraction (SPE) method was developed for the analysis of low concentration haloacetic acids (HAAs), a class of disinfection by-products formed from chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a sodium hydroxide eluent at a flow rate of 0.8 ml/min, electrolytically generated gradients, and suppressed conductivity detection. To analyze the HAAs in real hospital wastewater samples, C18 pretreatment cartridge was utilized to reduce samples' turbidity. Preconcentration with SPE and matrix elimination with treatment cartridges were investigated and found to be able to obtain acceptable detection limits. Linearity, repeatability and detection limits of the above method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid were 2.61 microg/L and 1.30 microg/L, respectively, and the other three acids are ranging from 0.48 to 0.82 microg/L under 25-fold preconcentration. When the above optimization procedure was applied to three hospital wastewater samples with different treatment processes in Tianjin, it was found that the dichloroacetic acid was the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite were 91.28%, 63.61% and 79.50%, respectively. PMID:17966879

Sun, Ying-Xue; Gu, Ping

2007-01-01

264

Determination of pharmaceutically related compounds by suppressed ion chromatography: II. Interactions of analytes with the suppressor.  

PubMed

For the hyphenation of ion chromatography to nebulising detectors or mass spectrometry, suppression of the non-volatile ionic eluent to water is a required step. However, suppression of weakly acidic or weakly basic organic analytes can potentially lead to losses of analytes during suppression resulting from precipitation, hydrophobic adsorption onto the suppressor, or permeation of the analyte through the suppressor membranes. This study investigates the interactions between the suppressor and weak organic acid analytes, including pharmaceutically related compounds, for eluents containing organic solvent. Correlations were observed between analyte recovery rates after electrolytic suppression and the eluent composition, the suppression conditions, and the physico-chemical properties of the analytes. These results suggest that hydrophobic adsorption interactions occur in the electrolytic suppressor and that these interactions are ameliorated by the addition to the eluent of high levels of organic solvents, especially acetonitrile. Use of eluents containing 80% acetonitrile resulted in very low losses of analyte during suppression. Recovery experiments conducted in various compartments of the electrolytic suppressor showed that some analytes permeated through the suppressor membrane into the regenerant chambers, but this could be prevented by adding organic solvent to the regenerant solution. It was also noted that analyte losses increased with ageing of the electrolytic suppressors. Chemical suppression avoids some of the analyte losses observed with an electrolytic suppressor, but when used under the correct conditions, electrolytic suppressors gave close to equivalent performance to chemical suppressors. PMID:22239961

Karu, Naama; Dicinoski, Greg W; Hanna-Brown, Melissa; Haddad, Paul R

2012-02-10

265

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

PubMed

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

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

2013-01-20

266

Detection of metabolites of trapped humans using ion mobility spectrometry coupled with gas chromatography.  

PubMed

For the first time, ion mobility spectrometry coupled with rapid gas chromatography, using multicapillary columns, was applied for the development of a pattern of signs of life for the localization of entrapped victims after disaster events (e.g., earthquake, terroristic attack). During a simulation experiment with entrapped volunteers, 12 human metabolites could be detected in the air of the void with sufficient sensitivity to enable a valid decision on the presence of a living person. Using a basic normalized summation of the measured concentrations, all volunteers involved in the particular experiments could be recognized only few minutes after they entered the simulation void and after less than 3 min of analysis time. An additional independent validation experiment enabled the recognition of a person in a room of ?25 m(3) after ?30 min with sufficiently high sensitivity to detect even a person briefly leaving the room. Undoubtedly, additional work must be done on analysis time and weight of the equipment, as well as on validation during real disaster events. However, the enormous potential of the method as a significantly helpful tool for search-and-rescue operations, in addition to trained canines, could be demonstrated. PMID:23249433

Vautz, Wolfgang; Slodzynski, Rafael; Hariharan, Chandrasekhara; Seifert, Luzia; Nolte, Jürgen; Fobbe, Rita; Sielemann, Stefanie; Lao, Bolan C; Huo, Ran; Thomas, C L Paul; Hildebrand, Lars

2013-02-19

267

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

SciTech Connect

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

Best, D.

2010-08-04

268

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

SciTech Connect

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

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

2011-01-30

269

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

SciTech Connect

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

Chadwick, J.L.

1995-04-01

270

The relationship between Candida species charge density and chitosan activity evaluated by ion-exchange chromatography.  

PubMed

Chitosan, a natural biopolymer presents antifungal activity that seems to be dependent on the interaction of its cationic amino groups and yeast cell surface. In this work we used ion-exchange chromatography to assess the surface charge density of Candida species and subsequently to relate this with their sensitivity profile to chitosan. The ability of several strains from distinct Candida species to interact with strong anionic and cationic exchangers was tested and the yeasts charge surface was assessed by measuring the zeta potential. Our results showed that all the yeast cells tested presented no interaction with the cationic resin and a species-related pattern of interaction was observed with the anionic resin. Specifically, regarding the Q-Sepharose support, Candida glabrata showed the lower retention affinity, followed by Candida albicans, presenting Candida tropicalis an intermediate profile; Candida parapsilosis and Candida guilliermondii revealed a stronger ionic interaction. The yeasts retention synergy in the anionic resin corroborates with the zeta potential outcomes. The behavior observed fit with sensitivity patterns to chitosan as the most susceptible species to chitosan presented higher affinity to the anionic resin in contrast to the less sensitive ones (C. albicans and C. glabrata). This data confirms and reinforces that chitosan activity is probably mediated by an ionic reaction between its amino free groups and ionic charges at the cell surface. PMID:22080045

Palmeira-de-Oliveira, A; Passarinha, L A; Gaspar, C; Palmeira-de-Oliveira, R; Sarmento, B; Martinez-de-Oliveira, J; Pina-Vaz, C; Rodrigues, A G; Queiroz, J A

2011-12-01

271

Analysis of psilocybin and psilocin in Psilocybe subcubensis GUZMÁN by ion mobility spectrometry and gas chromatography–mass spectrometry  

Microsoft Academic Search

A new method has been developed for the rapid analysis of psilocybin and\\/or psilocin in fungus material using ion mobility spectrometry. Quantitative analysis was performed by gas chromatography–mass spectrometry after a simple one-step extraction involving homogenization of the dried fruit bodies of fungi in chloroform and derivatization with MSTFA. The proposed methods resulted in rapid procedures useful in analyzing psychotropic

Thomas Keller; Andrea Schneider; Priska Regenscheit; Richard Dirnhofer; Thomas Rücker; Jürgen Jaspers; Wolfgang Kisser

1999-01-01

272

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

Microsoft Academic Search

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

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

1992-01-01

273

Quantitative Silver Ion Thin Layer Chromatography of Triacylglycerols from Sunflower Oils Differing in the Level of Linoleic Acid  

Microsoft Academic Search

Eight samples of sunflower oil with different linoleic acid contents (9–63{%}) were subjected to a triacylglycerol (TAG) analysis by silver-ion thin-layer chromatography with densitometric quantification. In spite of this substantial change in the fatty acid composition, the relative content of the component TAG classes in the sum of polyunsaturated triacylglycerols remains constant. Thus, a characteristic fingerprint of sunflower oil TAG

Ilko Marekov; Roumyana Tarandjiiska; Svetlana Momchilova; Boryana Nikolova-Damyanova

2008-01-01

274

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

Microsoft Academic Search

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

Wen Huang; Yinchun Gu; Hai Niu

2008-01-01

275

The determination of hydrotropes in detergent products by reverse-phase and ion-pair high performance liquid chromatography  

Microsoft Academic Search

The three aromatic sulfonates most commonly used as hydrotropes in detergent products can be qualitatively and quantitatively\\u000a determined by high performance liquid chromatography (HPLC). Reverse-phase and paired-ion methods are described for separating\\u000a sodium toluene, xylene and cumene sulfonates using conventional C18, C8, hexyl, and cyano columns as well as radially compressed\\u000a HPLC cartridges. Ultraviolet (UV) detection at 254 nm gives

B. P. McPherson; N. Omelczenko

1983-01-01

276

Quantification of four arsenic species in fruit juices by ion-chromatography–inductively coupled plasma–mass spectrometry  

Microsoft Academic Search

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

Sean D. Conklin; Peter E. Chen

2012-01-01

277

Arsenic speciation analysis of human urine using ion exchange chromatography coupled to inductively coupled plasma mass spectrometry  

Microsoft Academic Search

A sensitive and robust method for the determination of seven inorganic and organic arsenic species was developed using ion exchange chromatography combined with inductively coupled plasma mass spectrometry (IC-ICP-MS). Both anion and cation exchange columns were used in a complementary fashion. Arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) were selectively separated by an anion exchange column

Ruimin Xie; Willie Johnson; Steve Spayd; Gene S. Hall; Brian Buckley

2006-01-01

278

Optimizing Ion Chromatography-Inductively Coupled Plasma Mass Spectrometry for Speciation Analysis of Arsenic, Chromium and Bromine in Water Samples  

Microsoft Academic Search

Inductively coupled plasma mass spectrometry (ICP–MS) was coupled as a multielement detector for ion chromatography (IC) in analysis of chromium, arsenic and bromine species. The efforts were focused on selecting instrumental and operating conditions suitable for IC–ICP–MS. The choice of the eluent for IC was found to be critical. Ammonium buffer and nitric acid were suitable eluents since they did

Mari Pantsar-kallio; Pentti K. G. Manninen

1999-01-01

279

Simultaneous determination of toxic arsenic and chromium species in water samples by ion chromatography-inductively coupled plasma mass spectrometry  

Microsoft Academic Search

A method based on ion chromatography in conjunction with inductively coupled plasma mass spectrometry is presented for simultaneous determination of toxic chromium and arsenic species: Cr(VI), As(III) and As(V) using KNO3 at pH 9.8 as eluent. Cr(III), dimethylarsinate, monomethylarsonate, arsenobetaine and arsenocholine did not interfere with the analysis, since Cr(III) was eliminated before analysis and As species were separated from

Mari Pantsar-Kallio; Pentti K. G. Manninen

1997-01-01

280

Confirmatory method for sulfonamide residues in animal tissues by gas chromatography and pulsed positive ion-negative ion-chemical ionization mass spectrometry.  

PubMed

A confirmatory method has been developed for determination of 13 sulfonamides in edible tissues. The assay involves extraction from a solution resulting from a screening procedure by liquid chromatography and subsequent derivatization. Sulfachloropyridazine (SCP), sulfadiazine (SDA), sulfadimethoxine (SDM), sulfamethazine (SMZ), sulfamerazine (SME), sulfamethoxazole (SMX), sulfamethoxypyridazine (SMP), sulfapyridine (SPR), sulfaquinoxaline (SQX), and sulfathiazole (STA) were detected as the N1-methyl-N4-trifluoroacetyl derivatives, sulfaguanidine (SGU) as the same derivative after cyclization by hexafluoroacetylacetone, and sulfacetamide (SAC) as the methyl derivative. These sulfonamides were detected by gas chromatography and pulsed positive ion-negative ion-chemical ionization mass spectrometry with methane as the reactant gas, whereas sulfanilamide (SAA) was determined as the methyl derivative by electron-impact ionization. PMID:8241826

Mooser, A E; Koch, H

1993-01-01

281

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

NASA Astrophysics Data System (ADS)

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

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

1992-07-01

282

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

283

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

PubMed

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

Li, Jing; Zhu, Yan

2014-01-01

284

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

SciTech Connect

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

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

1985-05-01

285

Simultaneous determination of alkali and alkaline earth metals by ion chromatography with neutral carrier-based ion-selective electrode detector  

Microsoft Academic Search

Neutral carrier-based potentiometric detectors that can monitor both mono- and divalent cations have been developed for ion chromatography. The solvent polymeric membranes doped with a mixture of monesin methyl ester (MME; a monovalent cation-selective ionophore) and a divalent cation-selective ionophore (ETH 1117 or ETH 4030) have the combined properties of each single ionophore. These double ionophore-doped ISE membranes showed similar

Uk Sun Hong; Hye Kyong Kwon; Hakhyun Nam; Geun Sig Cha; Kyung-Hee Kwon; Ki-Jung Paeng

1995-01-01

286

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

PubMed

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

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

2010-12-01

287

Determination of Rare-Earth Elements in Geological Materials by Ion-Exchange Chromatography Separation and Induction Coupled Plasma Emission Spectroscopy.  

National Technical Information Service (NTIS)

A methodology for the analysis of Rare-Earth elements in geological samples has been developed. Ion exchange chromatography for the separation and induction coupled plasma emission spectroscopy for the analysis have been used. The columns with cationic re...

M. Diaz S. S. Iyer M. H. Kakazu L. C. P. Reino

1987-01-01

288

Identification of conjugated linoleic acid isomers in cheese by gas chromatography, silver ion high performance liquid chromatography and mass spectral reconstructed ion profiles. Comparison of chromatographic elution sequences  

Microsoft Academic Search

Commercial cheese products were analyzed for their composition and content of conjugated linoleic acid (CLA) isomers. The\\u000a total lipids were extracted from cheese using petroleum ether\\/diethyl ether and methylated using NaOCH3. The fatty acid methyl esters (FAME) were separated by gas chromatography (GC), using a 100-m polar capillary column, into\\u000a nine minor peaks besides that of the major rumenic acid,

Najibullah Sehat; John K. G. Kramer; Magdi M. Mossoba; Martin P. Yurawecz; John A. G. Roach; Klaus Eulitz; Kim M. Morehouse; Youh Ku

1998-01-01

289

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

PubMed

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

Miyamoto, Kenji; Fujimaki, Susumu; Ueda, Yoshihisa

2009-10-30

290

Development and validation of high-performance size exclusion chromatography methods to determine molecular size parameters of Haemophilus influenzae type b polysaccharides and conjugates.  

PubMed

Current vaccines against Haemophilus influenzae type b (Hib) consist of the polyribosyl ribitol phosphate (PRP) capsular polysaccharide chemically conjugated to a carrier protein. Among the various biological and physical analyses to be performed on these vaccines, the determination of the molecular size of the polysaccharide preparations throughout the conjugation process is particularly relevant. Comparison of results from high-performance size exclusion chromatography (HPSEC) with those routinely obtained using conventional gel permeation chromatography (CGPC) methods highlights the correlation between the two methods for determining the values of the chromatographic distribution coefficient (KD) of native and activated polysaccharides. The resulting data showed that the KD value is sufficient to characterize these polysaccharides using an HPSEC method. However, additional molecular size parameters (i.e., molar mass and hydrodynamic radius) are necessary for a reliable characterization of the tetanus conjugate (PRP-T), certainly due to the lattice-like structure of the conjugate. In practice, an absolute detection system in HPSEC composed of a low-angle light scattering detector, a viscometer, and a refractive index (RI) detector was used. As demonstrated, these HPSEC methods are rapid, accurate, and reproducible for the polysaccharides and their glycoconjugates and provide a relevant and more informative alternative to the current CGPC methods. PMID:24608090

Thiébaud, Jérôme; Fanget, Ingrid; Jaudinaud, Isabelle; Fourrichon, Laurence; Sabouraud, Alain; Talaga, Philippe; Uhlrich, Sylvie

2014-05-15

291

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

PubMed

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

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

2014-11-15

292

Determination of gas-phase produced ethyl parathion and toluene 2,4-diisocyanate by ion mobility spectrometry, gas chromatography and liquid chromatography.  

PubMed

Ethyl parathion and toluene 2,4-diisocyanate (2,4-TDI) vapors were generated using a vapor generation system that was designed for the evaporation of liquid samples at known flow rates. The vapor generation of parathion and 2,4-TDI posed a challenge because of their low volatility and tendency to absorb into surfaces of the vapor generation system. Experimental concentration of parathion was determined using gas chromatography-mass spectrometry (GC-MS). 2,4-TDI was derivatized with 1-(2-pyridyl)piperazine to urea derivative which concentration was analyzed using high performance liquid chromatography (HPLC). In addition, in combination with vapor generator, aspiration IMS was used for monitoring ion mobility cell (IMCell) and semiconductor cell (SCCell) responses to parathion and 2,4-TDI vapors. The chromatographic results correlated well with the IMCell response data, showing high specificity of IMS to parathion and 2,4-TDI. The concentrations of parathion and 2,4-TDI at the detection limit of IMS were significantly lower than IDLH threshold values of parathion or 2,4-TDI, demonstrating high sensitivity of IMS to both compounds. The IMS patterns of both chemicals and the influence of humidity on IMCell and SCCell sensitivity were analyzed. PMID:19071713

Nousiainen, Marjaana; Peräkorpi, Kaleva; Sillanpää, Mika

2007-05-15

293

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

NASA Technical Reports Server (NTRS)

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

Limero, Thomas F.; James, John T.

1994-01-01

294

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

PubMed

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

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

2012-08-01

295

[Determination of sulfite in flue gas desulfurization with seawater by ion chromatography].  

PubMed

The technology for flue gas desulfurization (FGD) with seawater is widely adopted by coal-fired power plants in coastal areas. SO2 in the flue gas is absorbed by alkaline seawater and transfered in aqueous phase as sulfite (SO3(2-)), and most SO3(2-) is transformed to sulfate (SO4(2-)) after an aeration process. The remaining SO3(2-) in the seawater discharged to sea area may be harmful to marine organism because of its biological toxicity, thus it is necessary to determine the concentration of SO3(2-) in the seawater for desulfurization. In this study, the method of determination of SO3(2-) in the seawater by ion chromatography was investigated. The separation was achieved on an IonPac AS14A column with 14 mmol/L NaOH-12 mmol/L Na2 CO3 solution as the mobile phase at a flow rate of 1.2 mL/min, and the detection was performed by a pulsed amperometric detector. Formaldehyde was added as a protective agent when sampling because the SO3(2-) is easy to be oxidized. To avoid the formation of Mg (OH)2 in the mobile phase with high pH value which might block the column, the Mg(2+) in seawater was precipitated by NaOH solution (pH 12.0) before sample determination. The method showed good linearity within the range of 0-100 mg/L with an average recovery of 116.8%. The method detection limit (MDL) reached as low as 0.05 mg/L. The relative standard deviations (RSD) for seawater matrix samples spiked at levels of 7.5, 25.0 and 75.0 mg/L were 2.1% 3.1% and 4.0% (n = 9) , respectively. The method has been applied for the determination of SO3(2-) in flue gas desulfurization seawater with the advantages of being fast, sensitive and selective. PMID:20352939

Yin, Liqian; Yuan, Dongxing; Guo, Juan; Liu, Xiyao

2009-11-01

296

Fragmentation study of hexanitrostilbene by ion trap multiple mass spectrometry and analysis by liquid chromatography/mass spectrometry.  

PubMed

The fragmentation pathways of three explosive compounds with similar structures, hexanitrostilbene (HNS), cyclotrimethylene trinitramine (RDX), and 2,4,6-trinitrotoluene (TNT), have been investigated by multiple mass spectrometry (MSn, n = 1, 2, 3) with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) sources. The electron capture mechanism for these compounds in negative ion APCI and ESI mode differs from the usual negative ion mechanism, deprotonation or addition of other species. This was shown for HNS and TNT, which both gave a [M]- anion but not a [M-H]- ion in APCI, and the [M]- anion of HNS was observed in ESI. The quantitative analysis of HNS was performed by liquid chromatography (LC)/ESI-MS, and the results obtained by the internal standard (ISTD) method were compared with those from the external standard (ESTD) method, demonstrating that both quantitation approaches are useful, with good sensitivity, reproducibility and linearity, and ESTD is preferable in routine applications. PMID:16941723

Fu, Xiaofang; Zhang, Yong; Shi, Shenhua; Gao, Fei; Wen, Dawei; Li, Wei; Liao, Yiping; Liu, Huwei

2006-01-01

297

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

PubMed

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

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

2014-06-20

298

[Simultaneous determination of 16 organic acids in feed additives by on-line enrichment and ion chromatography-mass spectrometry].  

PubMed

A novel analytical method for simultaneous determination of sixteen organic acids by on-line enrichment and ion chromatography-mass spectrometry (IC-MS) was developed. Online enrichment and separation of the organic acids were performed by ion chromatography on a homemade enrichment column and a homemade separation column. The qualitative and quantitative analyses of the organic acids were performed by mass spectrometry in selected ion monitoring (SIM) mode on the basis of atmospheric pressure chemical ionization (APCI) source in negative mode. The sample of 200 microL was injected for the analysis, and the on-line enrichment time was 3 min. The sodium hydroxide solution was used as a gradient elution system. The two columns made it possible to have a low limit of detection due to the good enrichment and separation capability. The sixteen organic acids were separated completely within 30 min. All curves showed good linearity within the test concentration ranges. The limits of detection (LODs) were between 0.01 and 0.22 mg/L, and the average recoveries were between 70.6% and 110.8%. The relative standard deviations (RSDs) were less than 6.3%. The results indicate that this method is simple, rapid, sensitive and accurate for the determination of the organic acids in feed additives. PMID:24822448

Xiong, Zhiyu; Dong, Ying; Zhou, Hongbin; Yu, Yang; Li, Jing; Sun, Li

2014-02-01

299

Determination of seven arsenic species in seafood by ion exchange chromatography coupled to inductively coupled plasma-mass spectrometry following microwave assisted extraction: Method validation and occurrence data  

Microsoft Academic Search

The determination of seven arsenic species in seafood was performed using ion exchange chromatography on an IonPac AS7 column with inductively coupled plasma mass spectrometry detection after microwave assisted extraction. The effect of five parameters on arsenic extraction recoveries was evaluated in certified reference materials. The recoveries of total arsenic and of arsenic species with the two best extraction media

Axelle Leufroy; Laurent Noël; Vincent Dufailly; Diane Beauchemin; Thierry Guérin

2011-01-01

300

MEASUREMENT OF RADIONUCLIDES USING ION CHROMATOGRAPHY AND FLOW-CELL SCINTILLATION COUNTING WITH PULSE SHAPE DISCRIMINATION  

SciTech Connect

Radiological characterization and monitoring is an important component of environmental management activities throughout the Department of Energy complex. Gamma-ray spectroscopy is the technology most often used for the detection of radionuclides. However, radionuclides which cannot easily be detected by gamma-ray spectroscopy, such as pure beta emitters and transuranics, pose special problems because their quantification generally requires labor intensive radiochemical separations procedures that are time consuming and impractical for field applications. This project focused on a technology for measuring transuranics and pure beta emitters relatively quickly and has the potential of being field deployable. The technology combines ion exchange liquid chromatography and on-line alpha/beta pulse shape discriminating scintillation counting to produce simultaneous alpha and beta chromatograms. The basic instrumentation upon which the project was based was purchased in the early 1990's. In its original commercial form, the instrumentation was capable of separating select activation/fission products in ionic forms from relatively pure aqueous samples. We subsequently developed the capability of separating and detecting actinides (thorium, uranium, neptunium, plutonium, americium, and curium) in less than 30 minutes (Reboul, 1993) and realized that the potential time savings over traditional radiochemical methods for isolating some of these radionuclides was significant. However, at that time, the technique had only been used for radionuclide concentrations that were considerably above environmental levels and for aqueous samples of relatively high chemical purity. For the technique to be useful in environmental applications, development work was needed in lowering detection limits; to be useful in applications involving non-aqueous matrices such as soils and sludges or complex aqueous matrices such as those encountered in waste samples, development work was needed in sample preparation and processing. The general goal of this project was to address the issues mentioned above, and in so doing transform an interesting laboratory technique of limited applicability into a robust field instrument suitable for environmental restoration and waste management applications. The project consisted of the following tasks: (1) development of a low background, flow-cell detector, (2) identification of sample chemical and radiological interferences, (3) development of protocols for processing waste and/or environmental samples, and (4) integration and testing of the prototype system. The scope of work associated with these tasks has been completed and the report for Tasks 1-3 was submitted previously. Presented here are the results for Task 4.

R. A. Fjeld; T.A. DeVol; J.D. Leyba

2000-03-30

301

Ion Chromatography Based Urine Amino Acid Profiling Applied for Diagnosis of Gastric Cancer  

PubMed Central

Aim. Amino acid metabolism in cancer patients differs from that in healthy people. In the study, we performed urine-free amino acid profile of gastric cancer at different stages and health subjects to explore potential biomarkers for diagnosing or screening gastric cancer. Methods. Forty three urine samples were collected from inpatients and healthy adults who were divided into 4 groups. Healthy adults were in group A (n = 15), early gastric cancer inpatients in group B (n = 7), and advanced gastric cancer inpatients in group C (n = 16); in addition, two healthy adults and three advanced gastric cancer inpatients were in group D (n = 5) to test models. We performed urine amino acids profile of each group by applying ion chromatography (IC) technique and analyzed urine amino acids according to chromatogram of amino acids standard solution. The data we obtained were processed with statistical analysis. A diagnostic model was constructed to discriminate gastric cancer from healthy individuals and another diagnostic model for clinical staging by principal component analysis. Differentiation performance was validated by the area under the curve (AUC) of receiver-operating characteristic (ROC) curves. Results. The urine-free amino acid profile of gastric cancer patients changed to a certain degree compared with that of healthy adults. Compared with healthy adult group, the levels of valine, isoleucine, and leucine increased (P < 0.05), but the levels of histidine and methionine decreased (P < 0.05), and aspartate decreased significantly (P < 0.01). The urine amino acid profile was also different between early and advanced gastric cancer groups. Compared with early gastric cancer, the levels of isoleucine and valine decreased in advanced gastric cancer (P < 0.05). A diagnosis model constructed for gastric cancer with AUC value of 0.936 tested by group D showed that 4 samples could coincide with it. Another diagnosis model for clinical staging with an AUC value of 0.902 tested by 3 advanced gastric cancer inpatients of group D showed that all could coincide with the model. Conclusions. The noticeable differences of urine-free amino acid profiles between gastric cancer patients and healthy adults indicate that such amino acids as valine, isoleucine, leucine, methionine, histidine and aspartate are important metabolites in cell multiplication and gene expression during tumor growth and metastatic process. The study suggests that urine-free amino acid profiling is of potential value for screening or diagnosing gastric cancer.

Fan, Jing; Hong, Jing; Hu, Jun-Duo; Chen, Jin-Lian

2012-01-01

302

Quantifying phytate in dairy digesta and feces: alkaline extraction and high-performance ion chromatography.  

PubMed

Development of an analytical method with appropriate combination of extraction and quantification approaches for undigested phytate in ruminant feces and digesta will advance knowledge of phytate degradation in ruminants and help to reduce phosphorus excretion. Established quantification methods give satisfactory results for feedstuffs and nonruminant manure but recovery of phytate is incomplete for ruminant feces and digesta because of their complex sample matrix and low ratio of phytate to inorganic P. The objective was to develop a robust, accurate, sensitive, and inexpensive method to extract and quantify phytate in feeds, ruminant feces, and digesta. Diets varying in phytate content were fed to dairy heifers, dry cows, and lactating cows to generate digesta and fecal samples of varying composition to challenge extraction and quantification methods. Samples were extracted with 0.5 M HCl or 0.25 M NaOH + 0.05 M EDTA. Acid extracts were mixed with 20% NaCl, alkaline extracts were acidified to final pH < 2, and then both extracts were clarified with C?? cartridges and 0.2-?m filters. High-performance ion chromatography (HPIC) was used to quantify phytate. In feed samples, the measured phytate was comparable in alkaline and acid extracts (2,965 vs. 3,085 ?g/g of DM). In digesta and fecal samples, alkaline extraction yielded greater estimates of phytate content than did acid extraction (40.7 vs. 33.6 and 202.9 vs. 144.4 ?g/g of DM for digesta and fecal samples, respectively). Analysis of alkaline extracts by HPIC is usually not possible because of sample matrix interferences; acidification and C(18)-cartridge elution of alkaline extracts prevented this interference. Pure phytate added to dry samples before extraction was almost completely recovered (88 to 105%), indicating high extraction efficiency, no adverse effect of extract clean-up procedures, and accurate quantification of phytate. The proposed method is rapid, inexpensive, robust, and combines the extraction power of NaOH-EDTA with the precision and sensitivity of HPIC quantification, allowing accurate quantification of phytate in feeds, ruminant digesta, and fecal samples. PMID:22612959

Ray, P P; Shang, C; Maguire, R O; Knowlton, K F

2012-06-01

303

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

Microsoft Academic Search

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

Aurélien Thomas; Christèle Widmer; Gérard Hopfgartner; Christian Staub

2007-01-01

304

Detection of trace levels of triclopyr using capillary gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.  

PubMed

Triclopyr, after esterification, is shown to be a suitable candidate for detection by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry forming a characteristic carboxylate anion which offers a high detection sensitivity. A detection limit of 70 fg reaching the ionizer is indicated. Low backgrounds and an absence of chemical interferences are shown for vegetation extracts, using a simple method of extraction and derivatisation. A similar behaviour is demonstrated for 2,4-D and 2,4,5-T. PMID:3379116

Begley, P; Foulger, B E

1988-04-01

305

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

SciTech Connect

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

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

1988-10-01

306

Column and high-performance size exclusion chromatography applications to the in vivo digestibility study of a thermoxidized and polymerized olive oil.  

PubMed

This study aimed (i) to design an in vivo model to study fat digestibility, and (ii) to apply this design to test the in vivo digestibility of a highly thermoxidized olive oil. True digestibility of unheated olive oil was tested 2, 4, 6, and 7 h after administering 1 g of olive oil/100 g body weight to young adult Wistar rats by means of esophageal probes. Remaining gastrointestinal lumen fat showed an inversely linear relationship (r= -0.9932; P < 0.001) with the length of the experiment. A 4-h test was considered adequate because after this period, half of the oil administer still remains in the lumen, making it possible to accurately measure the different nondigested, nonabsorbed thermoxidized compounds. In a second experiment, fresh olive oil (3.6 mg polar content/100 mg oil) was heated at 180 degrees C for 50 h in the presence of air; the polar content in this oil rose to 46.0 mg/100 mg oil. After 4 h, the true digestibility coefficient of 50-h heated olive oil did not significantly change, although it tended to decrease (24%) with respect to the unheated oil. Silica gel column chromatography and high-performance size exclusion chromatography were used to quantify nonthermoxidized and thermoxidized products present in the oils and in the gastrointestinal lumen after these test periods. True digestibility of the different thermoxidized compounds from the heated oil was 30-40%, whereas that of thermoxidized compounds from the fresh oil was much higher (approximately 80%). Nonoxidized triacylglycerol hydrolysis was negatively affected by the presence of large amounts of thermoxidized compounds. The present proposed model seems to be a useful tool for the study of thermoxidized oils. Data also show that thermoxidized compounds from abused olive oil are poorly but actively hydrolyzed and absorbed in vivo. PMID:10606041

Sánchez-Muniz, F J; Bastida, S; González-Muñoz, M J

1999-11-01

307

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

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.

Eiman M. Al-Muhareb; Fatma Karaca; Trevor J. Morgan; Alan A. Herod; Ian D. Bull; Rafael Kandiyoti [Imperial College, London (United Kingdom). Department of Chemical Engineering

2006-05-15

308

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

PubMed Central

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

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

2009-01-01

309

Metabolomic profiling of anionic metabolites in head and neck cancer cells by capillary ion chromatography with Orbitrap mass spectrometry.  

PubMed

A highly sensitive platform coupling capillary ion chromatography (Cap IC) with Q Exactive mass spectrometer has been developed for metabolic profiling of head and neck squamous cell carcinoma (HNSCC) cells. The Cap IC allowed an excellent separation of anionic polar metabolites, and the sensitivities increased by up to 100-fold compared to reversed-phase liquid chromatography and hydrophilic interaction chromatography performed at either high- or capillary-flow rates. The detection limits for a panel of standard metabolites were between 0.04 to 0.5 nmol/L (0.2 to 3.4 fmol) at a signal-to-noise ratio of 3. This platform was applied to an untargeted metabolomic analysis of head and neck cancer cells and stem-like cancer cells. Differential metabolomics analysis identified significant changes in energy metabolism pathways (e.g., glycolysis and tricarboxylic acid cycle). These experiments demonstrate Cap IC/MS as a powerful metabolomics tool by providing enhanced separation and sensitivity of polar metabolites combined with high resolution and accurate mass measurement (HR/AM) capabilities to differentiate isobaric metabolites. PMID:24766394

Wang, Junhua; Christison, Terri T; Misuno, Kaori; Lopez, Linda; Huhmer, Andreas F; Huang, Yingying; Hu, Shen

2014-05-20

310

Use of Two-Column Ion Chromatography for the Separation of Transition Metal Complexes of 1,2-Cyclohexanediaminetetraacetic Acid and Study of Complexation in Alkaline Solutions  

Microsoft Academic Search

The ion-chromatographic behavior of anionic transition metal complexes of 1,2-cyclohexanediaminetetraacetic acid (CHDTA) on polymeric anion exchangers was studied. It was demonstrated that two-column ion chromatography can be used for studying the complexation of CHDTA with transition metal ions in alkaline solutions. A method was proposed for the calculation of equilibrium constants of complexation reactions and stability constants from the data

N. V. Shcheglova; T. V. Popova

2004-01-01

311

Profiling the iron, copper and zinc content in primary neuron and astrocyte cultures by rapid online quantitative size exclusion chromatography-inductively coupled plasma-mass spectrometry.  

PubMed

Metals often determine the chemical reactivity of the proteins to which they are bound. Each cell in the body tightly maintains a unique metalloproteomic profile, mostly dependent on function. This paper describes an analytical online flow injection quantitative size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) method, which was applied to profiling the metal-binding proteins found in primary cultures of neurons and astrocytes. This method can be conducted using similar amounts of sample to those used for Western blotting (20-150 ?g protein), and has a turnaround time of <15 minutes. Metalloprotein standards for Fe (as ferritin), Cu and Zn (as superoxide dismutase-1) were used to construct multi-point calibration curves for online quantification of metalloproteins by SEC-ICP-MS. Homogenates of primary neuron and astrocyte cultures were analysed by SEC-ICP-MS. Online quantification by external calibration with metalloprotein standards determined the mass of metal eluting from the column relative to time (as pg s(-1)). Total on-column Fe, Cu and Zn detection limits ranged from 0.825 ± 0.005 ng to 13.6 ± 0.7 pg. Neurons and astrocytes exhibited distinct metalloprotein profiles, featuring both ubiquitous and unique metalloprotein species. Separation and detection by SEC-ICP-MS allows appraisal of these metalloproteins in their native state, and online quantification was achieved using this relatively simple external calibration process. PMID:24132241

Hare, Dominic J; Grubman, Alexandra; Ryan, Timothy M; Lothian, Amber; Liddell, Jeffrey R; Grimm, Rudolf; Matsuda, Toshiaki; Doble, Philip A; Cherny, Robert A; Bush, Ashley I; White, Anthony R; Masters, Colin L; Roberts, Blaine R

2013-12-01

312

Size-exclusion chromatography-mass spectrometry with m-nitrobenzyl alcohol as post-column additive for direct characterization of size variants of monoclonal antibodies.  

PubMed

Size-exclusion chromatography (SEC) is commonly used to monitor low molecular weight fragments and aggregates present in recombinant monoclonal antibody (mAb) biopharmaceuticals. It has been previously demonstrated that SEC could be coupled with mass spectrometry (MS) to directly measure the molecular weights of these protein species to aid in their identification. However, the use of certain mobile phase modifiers led to compromised sensitivity in MS detection. In this work, we demonstrate that the use of m-nitrobenzyl alcohol (m-NBA) as a post-column additive in an SEC-MS method is able to improve the ionization of antibody light chain and heavy chain approximately 7-fold and 2-fold, respectively, and thus allows the MS detection of low-abundance size variants present in mAb biopharmaceuticals. Application of the 15-min reducing SEC-UV/MS method enabled the direct identification of size variants present in an IgG1 mAb sample. One high molecular weight species observed under reducing conditions was identified to be a thioether-linked heterodimer of light chain and heavy chain. Multiple lower molecular weight species were found to result from cleavage of the heavy chain at a number of sites throughout the conserved sequence. The reducing SEC-UV/MS method provides a straightforward approach for identification of size variants present in mAb and may be applicable generally to all types of mAb biopharmaceuticals. PMID:24835510

Xu, Chong-Feng; Zang, Li; Weiskopf, Andrew

2014-06-01

313

Size exclusion chromatography with evaporative light scattering detection as a method for speciation analysis of polydimethylsiloxanes. III. Identification and determination of dimeticone and simeticone in pharmaceutical formulations.  

PubMed

The pharmaceutical industry is one of the more important sectors for the use of polydimethylsiloxanes (PDMS), which belong to the organosilicon polymers. In drugs for internal use, they are used as an active pharmaceutical ingredient (API) called dimeticone or simeticone. Due to their specific chemical nature, PDMS can have different degrees of polymerization, which determine the molecular weight and viscosity. The Pharmacopoeial monographs for dimeticone and simeticone, only give the permitted polymerization and viscosity range. It is, however, essential to know also the degree of polymerization or the specific molecular weight of PDMS that are present in pharmaceutical formulations. In the literature there is information about the impact of particle size, and thus molecular weight, on the toxicity, absorption and migration in living organisms. This study focused on the use of a developed method - the exclusion chromatography with evaporative light scattering detector (SEC-ELSD) - for identification and determination of dimeticone and simeticone in various pharmaceutical formulations. The method had a high degree of specificity and was suitable for speciation analysis of these polymers. So far the developed method has not been used in the control of medicinal products containing dimeticone or simeticone. PMID:21962761

Mojsiewicz-Pie?kowska, Krystyna

2012-01-25

314

Preferential interactions between ApoE-containing lipoproteins and A? revealed by a detection method that combines size exclusion chromatography with non-reducing gel-shift.  

PubMed

The association between apolipoprotein E (apoE) and amyloid-? peptide (A?) may significantly impact the function of both proteins, thus affecting the etiology of Alzheimer's disease (AD). However, apoE/A? interactions remain fundamentally defined by the stringency of the detection method. Here we use size exclusion chromatography (SEC) as a non-stringent approach to the detection of apoE/A? interactions in solution, specifically apoE and both endogenous and exogenous A? from plasma, CSF and astrocyte conditioned media. By SEC analysis, A? association with plasma and CNS lipoproteins is apoE-dependent. While endogenous A? elutes to specific human plasma lipoproteins distinct from those containing apoE, it is the apoE-containing lipoproteins that absorb excess amounts of exogenous A?40. In human CSF, apoE, endogenous A? and phospholipid elute in an almost identical profile, as do apoE, exogenous A? and phospholipid from astrocyte conditioned media. Combining SEC fractionation with subsequent analysis for SDS-stable apoE/A? complex reveals that apoE-containing astrocyte lipoproteins exhibit the most robust interactions with A?. Thus, standardization of the methods for detecting apoE/A? complex is necessary to determine its functional significance in the neuropathology characteristic of AD. Importantly, a systematic understanding of the role of apoE-containing plasma and CNS lipoproteins in A? homeostasis could potentially contribute to identifying a plasma biomarker currently over-looked because it has multiple components. PMID:22138302

LaDu, Mary Jo; Munson, Gregory W; Jungbauer, Lisa; Getz, Godfrey S; Reardon, Catherine A; Tai, Leon M; Yu, Chunjiang

2012-02-01

315

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

PubMed

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

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

2012-05-01

316

Fluorescence detection to determine proteins and humic-like substances fingerprints of exopolymeric substances (EPS) from biological sludges performed by size exclusion chromatography (SEC).  

PubMed

Fingerprints of extracellular polymeric substances (EPS) from activated and anaerobic granular sludges were obtained by size exclusion chromatography coupled to UV (210 and 280 nm) and fluorescence (221/350 nm (protein-like molecules) and 345/443 nm (humic-like substances)) detection. The total area below the peaks obtained with fluorescence detection is linked to the protein or humic-like substances EPS content. The EPS protein fingerprints, usually recorded with UV-280 nm, change dramatically, mainly in the relative size of peaks when they were measured by a florescence detection method. It means that the apparent molecular weight (aMW) distribution of EPS chomatophores and fluorophores is different. Protein-like and humic-like substances were found to be specific fingerprints of the EPS, affected by the type and origin of the bacterial aggregate and improve EPS sample differentiation. The protein-like fraction of EPS displays a wide range of aMW (>600 kDa-<10 kDa) whereas the humic-like substances fraction is composed of molecules of low aMW (6-<1.2 kDa). PMID:23347923

Bhatia, Divya; Bourven, Isabelle; Simon, Stéphane; Bordas, François; van Hullebusch, Eric D; Rossano, Stéphanie; Lens, Piet N L; Guibaud, Gilles

2013-03-01

317

Study of thermal aggregation of globulin from common buckwheat (Fagopyrum esculentum Moench) by size-exclusion chromatography and laser light scattering.  

PubMed

The heat-induced aggregation of common buckwheat (Fagopyrum esculetum Moench) globulin (BWG) was studied using size-exclusion chromatography (SEC) combined with on-line multiangle laser light scattering (MALLS) and quasielastic light scattering (QELS). The unheated BWG was found to exist mainly as a hexamer, with an estimated weight-average molecular weight (M(w)) of 342 000, close to that deduced from the genomic cloned data of 13S buckwheat globulin. The QELS data predicted that the hexamer exists as two annular trimeric rings (diameter approximately 10.8 nm) placed on top of each other, forming an oblate cylinder (height approximately 9.1 nm). Upon heating, hexamers and trimers were dissociated and then associated to form extended small aggregates, finally forming compact, large macroaggregates. N-Ethylmaleimide would favor macroaggregate formation and increased the molar masses and hydrodynamic radii of the soluble aggregates, suggesting a different aggregation process in the presence of the sulfhydryl-blocking agent. A plot of log hydrodynamic radius versus log molar mass showed changes in the slope during heat treatment, suggesting conformational transformation in the heat-denatured and aggregated BWG molecules. PMID:16417320

Choi, Siu-Mei; Ma, Ching-Yung

2006-01-25

318

Online Size-Exclusion High-Performance Liquid Chromatography Light Scattering and Differential Refractometry Methods to Determine Degree of Polymer Conjugation to Proteins and Protein–Protein or Protein–Ligand Association States  

Microsoft Academic Search

Characterizing the solution structure of protein–polymer conjugates and protein–ligand interactions is important in fields such as biotechnology and biochemistry. Size-exclusion high-performance liquid chromatography with online classical light scattering (LS), refractive index (RI), and UV detection offers a powerful tool in such characterization. Novel methods are presented utilizing LS, RI, and UV signals to rapidly determine the degree of conjugation and

Brent S. Kendrick; Bruce A. Kerwin; Byeong S. Chang; John S. Philo

2001-01-01

319

Application of gas chromatography-mass spectrometry with selected ion monitoring to the urinanalysis of 4-pyridoxic acid.  

PubMed

An analytical protocol has been developed for the analysis of urinary 4-pyridoxic acid (4-PA) by gas chromatography-mass spectrometry (GC-MS) for use in metabolic studies. Aliquots of urine were deproteinised and fractionated by isocratic reversed-phase high-performance liquid chromatography. The eluent fraction containing the 4-PA was collected, freeze-dried and silylated using N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. Derivatisation produced the mono-tert.-butyldimethylsilyl derivative of 4-PA lactone. This derivative was readily amenable to GC-MS analysis in the electron ionisation (70 eV) mode, yielding a prominent fragment ion at m/z 222 ([M-57]+; base peak). A heavy isotope-labelled derivative of pyridoxine [dideuteriated pyridoxine; 3-hydroxy-4-(hydroxymethyl)-5-[hydroxymethyl-2H2]-2-methylpyridine] has been synthesised and is being employed to determine the kinetics of labelling of the body pools of vitamin B6. Kinetic measurements are based on the determination of the relative proportions of metabolically produced deuterium-labelled and non-labelled 4-PA in urine, obtained from stable isotope ratios determined by low-resolution selected ion monitoring using a bench-top quadrupole GC-MS system. PMID:1452608

Leyland, D M; Evershed, R P; Edwards, R H; Beynon, R J

1992-10-23

320

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

PubMed

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

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

2009-02-01

321

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

EPA Science Inventory

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

322

Analysis of Underivatized Amino Acids in Geological Samples Using Ion-Pairing Liquid Chromatography and Electrospray Tandem Mass Spectrometry  

NASA Astrophysics Data System (ADS)

The capability of detecting biomarkers, such as amino acids, in chemically complex field samples is essential to establishing the knowledge required to search for chemical signatures of life in future planetary explorations. However, due to the complexities of in situ investigations, it is important to establish a new analytical scheme that utilizes a minimal amount of sample preparation. This paper reports the feasibility of a novel and sensitive technique, which has been established to quantitate amino acids in terrestrial crust samples directly without derivatization using volatile ion-pairing liquid chromatography and tandem mass spectrometry equipped with an electrospray ionization source. Adequate separation of 20 underivatized amino acids was achieved on a C18 capillary column within 26 min with nonafluoropentanoic acid (NFPA) as ion-pairing reagent. Each amino acid was identified from its retention time as well as from its characteristic parent-to-daughter ion transition. Using tandem mass spectrometry as a detection technique allows co-elution of some amino acids, as it is more specific than traditional spectrophotometric methods. In the present study, terrestrial samples collected from 3 different locations were analyzed for their water-extractable free amino acid contents, following the removal of metal and organic interferences via ion exchange procedures. This is the first time that amino acids in geological samples were directly determined quantitatively without complicated derivatization steps. Depending on the amino acid, the detection limits varied from 0.02 to 5.7 pmol with the use of a 1 ?l sample injection loop.

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

2008-04-01

323

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

PubMed

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

Brewer, Amandaa K; Striegel, André M

2011-04-15

324

Ion exchange chromatography of purified colonic mucus glycoproteins in inflammatory bowel disease: absence of a selective subclass defect.  

PubMed Central

Previous reports of a selective mucin subclass defect in ulcerative colitis have been reassessed using high performance chromatography (Superose 6 and Mono Q) for mucin purification and fractionation coupled with analysis of the fractions obtained using a combination of enzyme linked lectin and mucin antibody assays. Mucin samples purified from snap frozen rectal biopsy specimens obtained from patients with ulcerative colitis (n = 12), Crohn's disease (n = 5), and non-inflammatory bowel disease control subjects (n = 9) were subject to ion exchange chromatography using a continuous 0-0.35 mol/l NaCl salt gradient with a final 2.5 mol/l NaCl step. In all samples the major proportion (mean (SD) 86.7 (8.9)%) of the mucin detectable by wheat germ agglutinin binding eluted between 0.15 and 0.35 mol/l NaCl with no significant difference in elution profile between ulcerative colitis and control subjects. Significant elution of glycoprotein at less than 0.15 mol/l NaCl did occur, however, when a lower molecular weight mucin containing fraction which contained concanavalin A positive (glucose or mannose containing) material was analysed similarly. Similar ion exchange profiles were obtained when (3H)N-acetylglucosamine labelled mucins were studied after tissue culture of rectal biopsy specimens. No significant alteration in the ion exchange profile of purified mucins in ulcerative colitis has been shown in these studies. It is possible that the previously reported relative depletion of mucin subclass IV (eluting with 0.20 mol/l NaCl) may simply have reflected mucin depletion. Images Figure 2

Raouf, A; Parker, N; Iddon, D; Ryder, S; Langdon-Brown, B; Milton, J D; Walker, R; Rhodes, J M

1991-01-01

325

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

PubMed

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

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

2014-01-15

326

Purification of norovirus-like particles (VLPs) by ion exchange chromatography.  

PubMed

Recombinant expression of the norovirus capsid protein VP1 leads to self-assembly of non-infectious virus-like particles (VLPs), which are recognized as promising vaccine candidates against norovirus infections. To overcome the scalability issues connected to the ultracentrifugation-based purification strategies used in previous studies, an anion exchange-based purification method for norovirus VLPs was developed in this study. The method consists of precipitation by polyethylene glycol (PEG) and a single anion exchange chromatography step for purifying baculovirus-expressed GII.4 norovirus VLPs, which can be performed within one day. High product purity was obtained using chromatography. The purified material also contained fully assembled monodispersed VLPs, which were recognized by human sera containing polyclonal antibodies against norovirus GII.4. PMID:22265819

Koho, Tiia; Mäntylä, Tuomas; Laurinmäki, Pasi; Huhti, Leena; Butcher, Sarah J; Vesikari, Timo; Kulomaa, Markku S; Hytönen, Vesa P

2012-04-01

327

Separation of lead-203 from cyclotron-bombarded thallium targets by ion-exchange chromatography.  

PubMed

A simple method is presented for the separation of lead-203 from copper-backed thallium cyclotron targets. The procedure involves cation-exchange chromatography in hydrochloric acid and hydrochloric acid-acetone mixtures. Further purification involves anion-exchange chromatography in nitric acid-hydrobromic acid mixtures. A cation-exchange column containing 3.0 g of resin can handle as much as 15 g of thallium and 160 mg of copper. An anion-exchange column containing 3.0 g of resin can separate lead from up to 200 mg of thallium and 10 mg of copper. Separations are extremely sharp and less than 0.1 mug of thallium and less than 0.1 mug of copper remain in the lead-203 fraction. PMID:18963189

van der Walt, T N; Strelow, F W; Haasbroek, F J

1982-07-01

328

ION-pair liquid chromatography technique for the estimation of metformin in its multicomponent dosage forms  

Microsoft Academic Search

A simple, precise and accurate high performance liquid chromatography (HPLC) method was developed for the simultaneous estimation of metformin with gliclazide and glipizide present in multicomponent dosage forms. The method was carried out on Inertsil® C18 column. A mobile phase composed of acetonitrile–water containing camphor sulphonic acid (adjusted to pH 7 using 0.1 N sodium hydroxide; 75 mM) at a

M Vasudevan; J Ravi; S Ravisankar; B Suresh

2001-01-01

329

Determination of trace inorganic anions in seawater samples by ion chromatography using silica columns modified with cetyltrimethylammonium ion.  

PubMed

Conventional silica columns dynamically modified with cetyltrimethylammonium ions were evaluated for the determination of UV-absorbing bromide, nitrate, and nitrite in seawater samples. Cetyltrimethylammonium, which is a quaternary ammonium ion, was dynamically introduced onto silica surfaces. The first layer of the modifier was introduced by electrostatic interaction, whereas the second layer was introduced by hydrophobic interaction. The latter layer worked as the anion-exchange sites. The modified conventional silica columns could be used for separation of inorganic anions. Separation of authentic mixture of five anions was achieved within 17 min. The addition of 0.1 mM cetyltrimethylammonium ion to the eluent improved the repeatability of the retention time. Seawater samples could be directly injected onto the prepared conventional silica columns, and bromide, nitrate, and nitrite levels were determined to be 69, 0.13, and 0.016 ppm, respectively. PMID:18762921

Jiang, Xiao-Lin; Lim, Lee Wah; Takeuchi, Toyohide

2009-01-01

330

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

PubMed

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

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

2013-02-01

331

Analysis of oligosaccharides derived from heparin by ion-pair reversed-phase chromatography/mass spectrometry.  

PubMed

Current chromatographic and mass spectrometric techniques have limitations for analyzing heparin and heparin oligomers due to their high polarity, structural diversity, and sulfate lability. A rapid method for the analysis of heparin oligosaccharides was developed using ion-pair reversed-phase ultraperformance liquid chromatography coupled with electrospray quadruple time-of-flight mass spectrometry (IPRP-UPLC ESI Q-TOF MS). The method utilizes an optimized buffer system containing a linear pentylamine and a unique additive, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), to achieve highly efficient separation together with enhanced mass response of heparin oligosaccharides. Analyses of a heparin oligosaccharide test mixture, dp6 through dp22, reveal that the chromatographic conditions enable baseline resolution of isomeric heparin oligosaccharides (dp6) and produce intact molecular ions with no sulfate losses during mass spectrometric analysis. In addition, the described conditions are amenable to the detection of heparin oligosaccharides in positive ion mode, yield stronger positive ion signals for corresponding oligosaccharides compared to the negative ion mode, and allow identification of structural isomers by an MS/MS approach. Because sensitive detection of oligosaccharides is also achieved with ultraviolet (UV) detection, the method utilizes a dual detection scheme (UV and MS in series) along with IPRP UPLC to simultaneously obtain quantification (UV) and characterization (MS) data for heparin oligosaccharides. The broad potential of this new method is further demonstrated for the analysis of a low-molecular-weight heparin (LMWH) preparation from porcine heparin. This approach will be of particular utility for profiling the molecular entities of heparin materials, as well as for structural variability comparison for samples from various sources. PMID:19344114

Doneanu, Catalin E; Chen, Weibin; Gebler, John C

2009-05-01

332

Ionic composition of seawaters and derived saline solutions determined by ion chromatography and its relation to other water quality parameters.  

PubMed

Ion chromatography (IC) presents new possibilities for assessing information about environmental samples, namely waters of various compositions, ranging from high-purity water to highly saline ones. Constant proportion between major ions present in seawater, has been assumed in the past, from which the first practical equation relating chlorinity and salinity has been developed, being later substituted by a practical salinity scale, derived from conductivity measurements relative to a standard seawater, according to internationally accepted recommended procedures. Seawaters are characterized by salinity values around 35 while derived saline solutions may present considerable changes in ionic composition, conductivity, hence on salinity. Natural and anthropogenic phenomena may introduce new issues requiring clarification for which qualitative and quantitative information from additional sources is useful, e.g. ionic composition from IC. The different ranges of concentration of major and minor species present in seawater and derived saline solutions are a challenge for the optimization of a practical methodology for composition assessment in two single IC runs, one for anions and another one for cations, which has been attained in this work. Composition of saline solutions determined by IC was critically assessed in terms of anion-cation balance and further related to conductivity and salinity measurements aiming to evaluate the quality/completeness of ion chromatographic analyses performed at preselected conditions and to search for other meaningful relations for efficient recognition/distinction between saline solutions of different types. PMID:18829032

Gros, Natasa; Camões, M F; Oliveira, Cristina; Silva, M C R

2008-11-01

333

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

PubMed

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

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

2006-09-18

334

Electrostatic model for protein adsorption in ion-exchange chromatography and application to monoclonal antibodies, lysozyme and chymotrypsinogen A.  

PubMed

A model for the adsorption equilibrium of proteins in ion-exchange chromatography explicitly accounting for the effect of pH and salt concentration in the limit of highly diluted systems was developed. It is based on the use of DLVO theory to estimate the electrostatic interactions between the charged surface of the ion-exchanger and the proteins. The corresponding charge distributions were evaluated as a function of pH and salt concentration using a molecular approach. The model was verified for the adsorption equilibrium of lysozyme, chymotrypsinogen A and four industrial monoclonal antibodies on two strong cation-exchangers. The adsorption equilibrium constants of these proteins were determined experimentally at various pH values and salt concentrations and the model was fitted with a good agreement using three adjustable parameters for each protein in the whole range of experimental conditions. Despite the simplifications of the model regarding the geometry of the protein-ion-exchanger system, the physical meaning of the parameters was retained. PMID:20663509

Guélat, Bertrand; Ströhlein, Guido; Lattuada, Marco; Morbidelli, Massimo

2010-08-27

335

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

PubMed

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

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

2013-12-01

336

Analysis of commercial beverage products by size exclusion chromatography coupled with UV-vis absorbance detection and dynamic surface tension detection.  

PubMed

Multidimensional analysis of instant coffee and barley beverage samples using size exclusion chromatography (SEC) combined with a dynamic surface tension detector (DSTD) and a UV-vis absorbance detector (UV) is reported. A unique finding of this study was the action of the tetrabutylammonium (TBA) cation as a modifying agent (with bromide as the counter anion) that substantially increased the surface pressure signal and sensitivity of many of the proteins in the chromatographically separated samples. The tetrabutylammonium bromide (TBAB) enhancement of the surface pressure signal was further investigated by studying the response of 12 commercial standard proteins (alpha-lactalbumin, beta-lactoglobulin, human serum albumin (HSA), albumin from chicken egg white (OVA), bovine serum albumin (BSA), hemoglobin, alpha-chymotrypsinogen A, cytochrome C, myoglobin, RNase A, carbonic anhydrase, and lysozyme) in buffer performed using flow injection analysis (FIA) coupled with the DSTD with and without various concentrations of TBAB. The FIA-DSTD data show that 1mM TBAB enhances sensitivity of HSA detection, by lowering the limit of detection (LOD) from 2mg/mL to 0.1mg/mL. Similarly, the LOD for BSA was reduced from 1mg/mL to 0.2mg/mL. These FIA-DSTD experiments allowed the detection conditions to be optimized for further SEC-UV/DSTD experiments. Thus, the SEC-UV/DSTD system has been optimized and successfully applied to the selective analysis of surface-active protein fractions in a commercial instant coffee sample and in a soluble barley sample. The complementary selectivity of using the DSTD relative to an absorbance detector is also demonstrated. PMID:20006112

Pierce, Karisa M; Bramanti, Emilia; Onor, Massimo; Spiniello, Roberto; Kangas, Alexandra; Skogerboe, Kristen J; Synovec, Robert E

2010-01-15

337

Determination of surface-bound hydroxypropylcellulose (HPC) on drug particles in colloidal dispersions using size exclusion chromatography: a comparison of ELS and RI detection.  

PubMed

Evaporative light scattering (ELS) and refractive index (RI) detection methods were evaluated for the determination of surface-bound hydroxypropylcellulose (HPC) on drug particles in colloidal dispersions. Size exclusion chromatography (SEC) was used to separate HPC from other components of the dispersions. The instrumental parameters of the ELS detector were optimized to obtain maximum peak intensity, adequate peak shape and minimal baseline noise by varying the mobile phase flow rate, nebulizer temperature, and evaporation temperature. The chromatographic method was validated using both detectors. The ELS detector response exhibited second order polynomial and linear double logarithmic correlation with concentration over a 10-300% range while the RI response was linear. The double logarithmic correlation simplified the calculation compared to using the polynomial fit, and it provided more accurate results compared to the linear fit approach. Total HPC was obtained by solubilizing all components of the dispersion and analyzing for HPC. Non-bound HPC was obtained by ultracentrifuging the dispersion and analyzing the supernatant for HPC concentration. Analysis for total- and non-bound HPC in a representative colloidal dispersion gave method precisions with R.S.D.s of 2.5 and 2.2% for ELS, and 4.5 and 2.4% for RI (n=4). HPC bound to the surface of the drug particles was determined by difference: % bound HPC=100%-% non-bound HPC. Resultant % bound HPC values ranged from 22.1 to 25.4% of available HPC. Both ELS and RI are satisfactory detection techniques for HPC quantitation and for determination of the proportion of HPC bound to drug colloid particles, and the assay results are comparable. PMID:16242886

Zhu, Limin; Seburg, Randal A; Tsai, Eric W

2006-03-18

338

Recovering Ga(III) from coordination complexes using pyridine 2,6-dicarboxylic acid chelation ion chromatography.  

PubMed

Ion exchange chelation chromatography is an effective means to extract metals from coordination complexes and biological samples; however there is a lack of data to verify the nature of metal complexes that can be successfully analysed using such a procedure. The aim of this study was to assess the capability of pyridine 2,6-dicarboxylic acid (PDCA) to extract and quantify Ga(III) from a range of environments using standard liquid chromatography apparatus. The PDCA chelation method generated a single Ga(III) peak with a retention time of 2.55 +/- 0.02 min, a precision of <2% and a limit of detection of 110 microM. Ga(III) hydroxide complexes (highest stability constant 15.66) were used to successfully cross-validate the chelation method with inductively coupled plasma mass spectrometry. The PDCA assay extracted 96.9 +/- 1.2% of the spiked Ga(III) from porcine mucus and 100.7 +/- 2.7% from a citrate complex (stability constant 10.02), but only ca 50% from an EDTA complex (stability constant 22.01). These data suggest that PDCA chelation can be considered a suitable alternative to inductively coupled plasma mass spectrometry for Ga(III) quantification from all but the most strongly bound coordinated complexes i.e. a stability constant of <15. PMID:20700886

Staff, K; Brown, M B; Hider, R C; Kong, X L; Friden, P; Jones, S A

2010-09-01

339

Analysis of Particle Content of Recombinant Adeno-Associated Virus Serotype 8 Vectors by Ion-Exchange Chromatography  

PubMed Central

Abstract Advances in adeno-associated virus (AAV)-mediated gene therapy have brought the possibility of commercial manufacturing of AAV vectors one step closer. To realize this prospect, a parallel effort with the goal of ever-increasing sophistication for AAV vector production technology and supporting assays will be required. Among the important release assays for a clinical gene therapy product, those monitoring potentially hazardous contaminants are most critical for patient safety. A prominent contaminant in many AAV vector preparations is vector particles lacking a genome, which can substantially increase the dose of AAV capsid proteins and lead to possible unwanted immunological consequences. Current methods to determine empty particle content suffer from inconsistency, are adversely affected by contaminants, or are not applicable to all serotypes. Here we describe the development of an ion-exchange chromatography-based assay that permits the rapid separation and relative quantification of AAV8 empty and full vector particles through the application of shallow gradients and a strong anion-exchange monolith chromatography medium.

Lock, Martin; Alvira, Mauricio R.

2012-01-01

340

Retention study of some cation-type compounds using bile acid sodium salts as ion pairing agents in liquid chromatography.  

PubMed

The possibility of forming ion-pairs between bile acids (sodium taurocholate, sodium taurodeoxycholate and sodium taurochenodeoxycholate) and different compounds (pralidoxime, obidoxime and pyridostigmine) having a cationic character has been studied in reversed-phase liquid chromatography (RP-LC). This study can be useful in understanding the role of bile acids in the transport of ionic species through hydrophobic membrane. The present study focused on the influence of mobile phase composition on the retention parameters of chosen compounds (percentage of acetonitrile, pH of aqueous component or ionic strength). For constant concentration of bile acids in aqueous component of mobile phase the functional dependencies between the logarithm of the retention factor (k) and the methanol content in the mobile phase followed a binomial pattern (U-shaped), with a minimum positioned within the interval 70-85% methanol. PMID:20960581

Radulescu, Medeea; Voicu, Victor; Medvedovici, Andrei; David, Victor

2011-08-01

341

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

342

Rapid Isothermal Gas Chromatography-Mass Spectrometry Method for Validating a Small Ion Mobility Spectrometer Sensor  

Microsoft Academic Search

A fast and reproducible isothermal gas chromatographic-mass spectrometric method for validating a small ion mobility spectrometer (IMS) sensor for detection of gaseous volatile organic compounds (VOCs) is presented. This method utilizes an automated cyclic valving (CV) sampling technique coupled to a gas chromatograph- mass spectrometer (GC\\/MS) in selected ion monitoring (SIM) mode (CV\\/GC\\/MS\\/ SIM). The sampling time is considerably reduced

Jerome A. Imonigie; Robert N. Walters; Molly M. Gribb

2006-01-01

343

ION-pair liquid chromatography technique for the estimation of metformin in its multicomponent dosage forms.  

PubMed

A simple, precise and accurate high performance liquid chromatography (HPLC) method was developed for the simultaneous estimation of metformin with gliclazide and glipizide present in multicomponent dosage forms. The method was carried out on Inertsil C(18) column. A mobile phase composed of acetonitrile-water containing camphor sulphonic acid (adjusted to pH 7 using 0.1 N sodium hydroxide; 75 mM) at a flow rate of 1 ml min(-1) was used for the separation. Detection was carried out at 225 nm. Tolbutamide was used as internal standard. Validation of the developed HPLC method was carried out. PMID:11274860

Vasudevan, M; Ravi, J; Ravisankar, S; Suresh, B

2001-04-01

344

Development of high-throughput liquid chromatography injected ion mobility quadrupole time-of-flight techniques for analysis of complex peptide mixtures  

Microsoft Academic Search

The development of a multidimensional approach involving high-performance liquid chromatography (LC), ion mobility spectrometry (IMS) and tandem mass spectrometry is described for the analysis of complex peptide mixtures. In this approach, peptides are separated based on differences in their LC retention times and mobilities (as ions drift through He) prior to being introduced into a quadrupole\\/octopole\\/time-of-flight mass spectrometer. The initial

Young Jin Lee; Cherokee S Hoaglund-Hyzera; Catherine A Srebalus Barnes; Amy E Hilderbrand; Stephen J Valentine; David E Clemmer

2002-01-01

345

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

PubMed

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

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

2009-12-15

346

Ion-exchange chromatography of a dinucleotide preparation from controlled alkaline hydrolysis of ribonucleic acids  

PubMed Central

With the aim of preparing the 16 possible ribodinucleotides derived from the four principal ribonucleotides, we made a kinetic study to determine the optimum conditions for a partial alkaline hydrolysis of RNA. Satisfactory results were obtained when the hydrolysis of RNA (1g.) in 0·2m-sodium hydroxide (100ml.) at 37° was ceased approx. 10min. after the start of the reaction. The relative yields of the monomer, dimer and trimer fractions were approx. 41:30:15 in E260 units, indicating that the reaction conditions were reasonably close to those required from kinetic considerations. The partial alkaline hydrolysate was chromatographed on a column of DEAE-Sephadex A-25 in the presence of 7m-urea. The dinucleotide fraction thus obtained was subjected to a subsequent chromatography on Dowex 1 (X2) under acidic conditions to separate the mixture according to base composition and base sequence. The results were satisfactory, and most of the 32 dinucleotides [i.e. 16 XpYp(3?) plus 16 XpYp(2?)] were fractionated by this single chromatographic procedure. The present method should be useful for further study of oligonucleotides as a time-saving method for the simultaneous preparation of a variety of dinucleotides. Further, examination of the present chromatographic pattern has provided several empirical criteria useful for the identification of oligonucleotides other than dimers appearing in the elution profile of Dowex 1 (X2) column chromatography under similar conditions.

Satoh, Kimihiko; Inoue, Yasuo

1969-01-01

347

Rapid ion chromatography of l-ascorbic acid, nitrite, sulfite, oxalate, iodide and thiosulfate by isocratic elution utilizing a postcolumn reaction with cerium(IV) and fluorescence detection  

Microsoft Academic Search

Rapid separation and determination of mixtures of l-ascorbic acid, nitrite, sulfite, oxalate, iodide and thiosulfate by conventional ion chromatography is often difficult due to incomplete separation of l-ascorbic acid and nitrite from the water peak when using eluents giving short elution times for iodide and thiosulfate. Separation of the six species within about 15 min has been achieved by isocratic

Yasuyuki Miura; Masahide Hatakeyama; Thikara Hosino; Paul R. Haddad

2002-01-01

348

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...

349

Improved ion chromatography–integrated pulsed amperometric detection method for the evaluation of biogenic amines in food of vegetable or animal origin and in fermented foods  

Microsoft Academic Search

An improved method for the simultaneous determination of underivatized biogenic amines, cadaverine, putrescine, spermidine, histamine, tyramine and some amino acids precursors, histidine and tyrosine, in food products, based on ion-exchange chromatography (IC) with integrated pulsed amperometric detection (IPAD) has been developed. The method was successfully used for the analysis of biogenic amines and amino acids in food both of vegetable

R Draisci; L Giannetti; P Boria; L Lucentini; L Palleschi; S Cavalli

1998-01-01

350

Determination of trace metals in waters and compost by on-line precipitation coupled to flame atomic absorption spectrophotometry or ion chromatography  

Microsoft Academic Search

A general rapid on-line preconcentration method for the determination of trace metals coupled to flame atomic absorption spectrophotometry (FAAS) or ion chromatography (IC) with spectrophotometric detection is described. The method is based on the on-line precipitation of metal hydroxides with sodium hydroxide and their dissolution in a small volume of nitric acid solution. All the chemical and physical variables that

A. Mart??n-Esteban; R. M. Garcinuño; S. Angelino; P. Fernández; C. Cámara

1999-01-01

351

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

Microsoft Academic Search

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

L. Bednarczyk; I. Fidelis

1978-01-01

352

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...

353

An ion exchange liquid chromatography\\/mass spectrometry method for the determination of reduced and oxidized glutathione and glutathione conjugates in hepatocytes  

Microsoft Academic Search

A rugged LC-MS\\/MS method was developed to quantify reduced and oxidized glutathione (GSH and GSSG, respectively) in rat hepatocytes. In addition, GSH conjugates can be detected, characterized and measured in the same analysis. Samples were treated with acetonitrile and iodoacetic acid to precipitate proteins and trap free GSH, respectively. These highly polar analytes were separated by ion exchange chromatography using

Amy F Loughlin; Gary L Skiles; David W Alberts; William H Schaefer

2001-01-01

354

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

ERIC Educational Resources Information Center

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

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

2004-01-01

355

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...

356

Determination of the main hydrolysis products of organophosphorus nerve agents, methylphosphonic acids, in human serum by indirect photometric detection ion chromatography  

Microsoft Academic Search

For the verification of the use of chemical warfare agents (CWA), sarin, soman and VX, a simple rapid and accurate method which allows us to simultaneously determine their degradation products, isopropyl methylphosphonic acid (IPMPA), pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), in human serum, was explored by indirect photometric detection ion chromatography (IPD-IC) which employs

M. Katagi; M. Nishikawa; M. Tatsuno; H. Tsuchihashi

1997-01-01

357

Determination of niacin in fresh and dry cured pork products by ion chromatography: experimental design approach for the optimisation of nicotinic acid separation  

Microsoft Academic Search

A simple and robust method to determine the niacin level in fresh and dry-cured pork products by ion chromatography is reported. The analytical procedure includes an acidic hydrolysis to free all the bound forms (NAD and NADP) and to convert all the niacin into nicotinic acid, after that the chromatographic separation of the acid form is performed by a cation-exchange

G. Saccani; E. Tanzi; S. Mallozzi; S. Cavalli

2005-01-01

358

Confirmatory analysis method for zeranol, its metabolites and related mycotoxins in urine by liquid chromatography-negative ion electrospray tandem mass spectrometry  

Microsoft Academic Search

The determination of the banned anabolic substance zeranol and the metabolites taleranol and zearalanone in bovine urine is complicated by the occurrence of the structurally-related mycotoxin zearalenone and the corresponding ?- and ?-zearalenol metabolites which possess similar estrogenic properties. A liquid chromatography-negative ion electrospray tandem mass spectrometric method is presented for the confirmatory analysis of all six resorcylic acid lactones

E. O van Bennekom; L. Brouwer; E. H. M. Laurant; H. Hooijerink; M. W. F. Nielen

2002-01-01

359

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

Microsoft Academic Search

Mixing coal fly ash with an organic waste increases macronutrient content and may make land application of fly ash a viable disposal alternative. However, trace element chemistry of these mixed waste products warrants investigation. Speciation of As and Se in soil solutions of fly ash-, poultry litter- and sewage sludge-amended soils was determined over a 10-day period by ion chromatography

B. P. Jackson; W. P. Miller

1999-01-01

360

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

PubMed

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

Cecchi, Teresa; Marcotulli, Federica

2013-11-01

361

Dynamic chelation ion chromatography of transition and heavy metal ions using a mobile phase containing 4-chlorodipicolinic acid.  

PubMed

The chromatographic behaviour of selected transition and heavy metal ions, the lanthanides, uranium and aluminium, on a neutral polystyrene-divinylbenzene (PS-DVB) stationary phase (7 microm Hamilton PRP-1) dynamically modified with 4-chlorodipicolinic acid, was investigated to evaluate retention characteristics. Complicated retention factor against pH plots were found for these metals demonstrating changes in retention order. It was concluded that complexation between the metal ions and the ligand adsorbed on the resin was strongly influenced by the decrease in dynamic loading with increase in pH, coinciding with changes in the metal-to-ligand ratio in the mobile phase. Possible reversed-phase interactions between metal-chlorodipicolinic acid complexes and the hydrophobic PS-DVB stationary phase also could not be ruled out. An eluent of 0.25 mM chlorodipicolinic acid, I M potassium nitrate at pH 2.2 was suitable for the separation of seven transition and heavy metal ions in under 20 min on a 250 x 4.6 mm column (with 50-mm guard column), determined in a certified water sample with good accuracy (R2 > or = 0.994) and reproducibility (RSD 1-4.2%). Pb(II), Cd(II) and Cu(II) were additionally analysed in <10 min in a more complicated certified rice flour matrix, using the same eluent but adjusted to pH 1.5, again with good accuracy (R2 > or = 0.998) and reproducibility (RSD 0.48-1.38%). PMID:12058928

Shaw, Matthew J; Jone, Phil; Nesterenko, Pavel N

2002-04-12

362

Nuclear stopping in heavy-ion collisions at 100 MeV/nucleon from inclusive and exclusive neutral pion measurements  

SciTech Connect

Inclusive and exclusive measurements of neutral pions in heavy-ion collisions around 100 MeV/nucleon, carried out in a near 4{pi} geometry, have been analyzed to obtain information on the nuclear stopping of the projectile. Stopping of the projectile has been investigated by the analysis of the source velocity, of the distribution of the energetic products of the collisions, and of the associated rapidity distribution of the baryon matter. Collisions were classified according to their centrality by the charged particle multiplicity. Clear evidence for this phenomenon has been obtained by the study of different observables. Both stopping and reabsorption effects play an essential role in the interpretation of the results. {copyright} {ital 1996 The American Physical Society.}

Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S.; Riggi, F.; Russo, A.C.; Russo, G.; Turrisi, R. [Istituto Nazionale di Fisica Nucleare, Sez. di Catania, Corso Italia, 57 -- I 95129 Catania (Italy)]|[Dipartimento di Fisica dell`Universita di Catania, Corso Italia, 57 -- I 95129 Catania (Italy)]|[Istituto Nazionale di Fisica Nucleare, Laboratorio Nazionale del Sud, Via S. Sofia, 44 -- I 95123 Catania (Italy)

1996-04-01

363

Determination of rare earth elements by ion chromatography. Separation procedure optimization  

Microsoft Academic Search

In the development of research on materials for optical fibres production, the use of pure lanthanum compounds is very important for the manufacture of glasses, since they can play an important role for signal enhancement by fluorescence emission. For this purpose, an ion exchange chromatographic method for rare earth determination has been studied and optimized. The analytical column involved was

Maria Concetta Bruzzoniti; Edoardo Mentasti; Corrado Sarzanini; Marco Braglia; Giuseppe Cocito; Jörg Kraus

1996-01-01

364

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...

365

Use of ion chromatography for the measurement of organic acids in fruit juices  

Microsoft Academic Search

A gradient ion chromatographic method to separate and determine main organic acids in fruit juices was developed. The method allows the separation of organic anions on Dionex OMNI PAC PAX-500 column by NaOH gradient elution and conductometric detection. The main organic acids of fruit juices (citric, malic, tartaric) were separated together with other less abundant acids. More than 500 samples

G. Saccani; S. Gherardi; A. Trifirò; C. Soresi Bordini; M. Calza; C. Freddi

1995-01-01

366

Separation of organotin compounds by ion-exchange chromatography and their determination by inverse voltammetry.  

PubMed

An ion exchange procedure was developed for the enrichment, separation and quantification of butyltin and phenyltin species, which show very close half wave potentials by their voltammetric determination. As a case study the separation of dibutyltin (DBT) from triphenyltin (TPT) was investigated. Among different ion exchangers tested, the strong acid ion exchanger PUROLITE C100H, used for industrial purposes, was found to be the most suitable. By using a resin bed volume of 25 mL, a flow rate of the feed solution of 1 mL/min and 3 M HCl in methanol as eluent with a flow rate of 0.5 mL/min, a recovery rate of each species of about 80% could be achieved. The detection limit for the determination of DBT and TPT by anodic stripping voltammetry after their separation and enrichment by the above mentioned ion exchange procedure was found to be 0.4 ng/mL for DBT and 6 ng/mL for TPT in the feed solution, respectively. The applicability of the whole procedure was tested on a sediment candidate reference material of BCR (Bureau of Reference Community). PMID:11371062

Ochsenkühn, K M; Ochsenkühn-Petropoulou, M; Tsopelas, F; Mendrinos, L

2001-04-01

367

High-resolution determination of {sup 147}Pm in urine using dynamic ion-exchange chromatography  

SciTech Connect

Ion exchange preconcentration followed by HPLC purification prior to scintillation counting was used to measure the concentration of {sup 147}Pm in urine. the detection limit for this method was found to be 0.1 Bq (3 fg) of {sup 147}Pm in 500 ml of urine.

Elchuk, S.; Lucy, C.A.; Burns, K.I. [Chalk River Labs., Ontario (Canada)

1992-10-15

368

Determination of trace perchlorate in high-salinity water samples by ion chromatography with on-line preconcentration and preelution.  

PubMed

A simple, automated system for the determination of trace perchlorate by ion chromatography (IC) with an online preconcentration technique is reported. The sample is preconcentrated, and less strongly held ions preeluted before the analyte is transferred to the principal separation system. This approach provides low limits of detection (LOD) and is particularly robust toward the effect of high concentrations of common anions, such as those present in groundwater samples. It compares favorably with currently promulgated EPA method 314.0. The LOD (S/N = 3) is 0.77 microg/L for a 2-mL reagent water sample and decreases more-or-less proportionately with increasing sample volume, at least up to 20 mL. Even with a sample of conductivity 14.7 mS/cm (approximately that of 0.1 M Na2SO4), the recovery of added perchlorate at the 25.0 microg/L level was still 92%. The concentration of added perchlorate in the range of 1-400 microg/L was linearly correlated to the peak area, with an r2 value of 0.9997. The recovery of perchlorate from artificial samples with different conductivity by the present method compares favorably with those from the currently recommended EPA Method. The ability of this approach to remove matrix interferences suggests that it would be also promising for perchlorate analysis in other challenging samples. PMID:12585505

Tian, Kang; Dasgupta, Purnendu K; Anderson, Todd A

2003-02-01

369

Analysis of fluorescently labeled sugars by reversed-phase ion-pairing high-performance liquid chromatography.  

PubMed

Reducing sugars, including monosaccharides, disaccharides, and a trisaccharide, are derivatized by reductive amination with 7-amino-1,3-naphthalene disulfonic acid. Reversed-phase ion-pairing high-performance liquid chromatography is then used to separate these visibly fluorescent, charged conjugates. Isocratic elution with triethylamine-acetic acid from a phenyl column, a C18 column, and C18 and phenyl columns in series gives good separations of a mixture of monosaccharides and a mixture of disaccharides and trisaccharides. Resolution of certain monosaccharides is enhanced by replacing triethylamine with a chiral amine and using gradient elution. Further enhancement of resolution is achieved by adding phenylboronic acid, an agent capable of complexing with the vicinal diol functionality present in many sugars. The trimethylamine-acetic acid eluant permits detection by either ultraviolet absorbance or fluorescence, and the addition of a chiral ion-pairing agent or a phenylboronic acid complexing agent necessitates fluorescence detection. A reversible Schiff base form of the fluorescent sugar conjugate is prepared; it is sufficiently stable to perform fractionations but sufficiently unstable to be converted to a fluorescent label and reducing sugar. PMID:7738134

Kim, Y S; Liu, J; Han, X J; Pervin, A; Linhardt, R J

1995-04-01

370

Analysis of hexavalent chromium in Colla corii asini with on-line sample pretreatment valve-switching ion chromatography.  

PubMed

An ion chromatography (IC) system with on-line sample pretreatment using valve-switching technique was developed for the determination of hexavalent chromium (Cr(VI)) in Colla corii asini. Colla corii asini is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a collection loop to analytical columns, with matrix eliminated on-line. Under the optimized separation conditions, the method showed good linearity (r=0.9998) in the range of 0.004-1.0mg/L and satisfactory repeatability (RSD<3%, n=6). The limit of detection (LOD) was 1.4?g/L (S/N=3). The average spiked recoveries of Cr(VI) were 93.4-102.0%. The result showed that the on-line sample pretreatment IC system was convenient and practical for the determination of trace Cr(VI) in Colla corii asini samples. PMID:23891376

Yang, Yuling; He, Jie; Huang, Zhongping; Zhong, Naifei; Zhu, Zuoyi; Jiang, Renyu; You, Jinghua; Lu, Xiuyang; Zhu, Yan; He, Shiwei

2013-08-30

371

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

PubMed Central

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

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

2011-01-01

372

Single-column method of ion chromatography for the determination of common cations and some transition metals.  

PubMed

A single-column method for the simultaneous determination of common cations and transition metals in real samples is proposed in this paper. Eleven cations (copper, lithium, sodium, ammonium, potassium, cobalt, nickel, magnesium, calcium, strontium and zinc) were separated and analyzed by means of ion chromatography using an isocratic elution with 2.5 mM methane sulfonic acid and 0.8 mM oxalic acid as mobile phase, IonPac SCS1 (250 mm x 4 mm I.D.) as the separation column and non-suppressed conductor detection. Optimized analytical conditions were further validated in terms of accuracy, precision and total uncertainty and the results showed the reliability of the IC method. The relative standard deviations (RSDs) of the retention time and peak area were less than 0.04 and 1.30%, respectively. The coefficients of determination for cations ranged from 0.9988 to 1.000. The method developed was successfully applied to determination of cations in samples of beer and bottled mineral water. The spiked recoveries for the cations were 94-106%. The method was applied to beer and beverage without interferences. PMID:16483592

Zeng, Wenfang; Chen, Yongxin; Cui, Hairong; Wu, Feiyan; Zhu, Yan; Fritz, James S

2006-06-16

373

Determination of sulfite in dried garlic by reversed-phase ion-pairing liquid chromatography with post-column detection.  

PubMed

A method is described for determining sulfite in dried garlic. Garlic is extracted with an HCl solution to inhibit the formation of allicin, which interferes with the determination of sulfite. After cleanup of the extract on a C18 solid-phase extraction column, sulfite is converted to hydroxymethylsulfonate (HMS) by adding formaldehyde and heating to 50 degrees C. HMS is determined by reversed-phase ion-pairing liquid chromatography with post-column detection. The post-column reaction system consists of the addition of KOH to convert HMS to sulfite ion, followed by the addition of 5,5'-dithiobis(2-nitrobenzoic acid) to produce 5-mercapto-2-nitrobenzoic acid which is detected spectrophotometrically at 450 nm. Background levels in unsulfited dried garlic equivalent to < 20 ppm SO2 were found. Recoveries of HMS from spiked garlic averaged 94.8% with a coefficient of variation of 3.8%. Sulfite was found in 13 of 21 samples of dried garlic produced in China, with sulfite ranging from 114 to 445 ppm. Sulfite was found in 60% of commercial dried garlic products purchased locally. The suitability of the Monier-Williams method for determining sulfite in garlic is discussed. PMID:12852574

Perfetti, Gracia A; Diachenko, Gregory W

2003-01-01

374

Isotope Analysis of Sulfur, Bromine, and Chlorine in Individual Anionic Species by Ion Chromatography/Multicollector-ICPMS.  

PubMed

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

Zakon, Yevgeni; Halicz, Ludwik; Gelman, Faina

2014-07-01

375

Simultaneous determination of 16 pyrethroid residues in tea samples using gas chromatography and ion trap mass spectrometry.  

PubMed

Pyrethroids are widely used in tea production, and pesticide residues in brewed tea are becoming a major issue. Thus, an appropriate control method of pyrethroid residues in tea samples has to be developed and used to reduce the potential health hazard from consumption of pyrethroids. A method is described here for the simultaneous determination of 16 pyrethroid residues in tea samples. The insecticides were extracted using acetone and then underwent cleanup through a florisil column. Analysis was performed by gas chromatography with ion trap mass spectrometry (GC IT-MS) in MS MS mode. Retention time and specific ions were used for identification. Recoveries at spiked levels (0.001-0.2 ?g/g) for the 16 pyrethroids ranged from 71.3% to 106.3%, and the coefficient of variation was less than 17% in each case. The limits of detection were from 0.001 to 0.05 ?g/g. The proposed method was successfully applied to determine pyrethroid residues in 25 brewed made tea samples. It was found that there were bifenthrin, cyfluthrin, lamda-cyhalothrin, cypermethrin, dicofol, fenpropathrin, fenvalerate, fluvalinate, and tetramethrin residues in different samples with levels ranging from 1.18-3071.29 ?g/kg. PMID:20875241

Kuang, Hua; Miao, Hong; Hou, Xiaolin; Zhao, Yunfeng; Wu, Yongning; Xu, Chuanlai

2010-10-01

376

[Study of chemical kinetics between pyrroloquinoline quinine and D-serine in body by ion-pair liquid chromatography].  

PubMed

As a new neurotransmitter present in the glial cells, D-serine (DSer) plays an important role in central nervous system diseases. Pyrroloquinoline quinine (PQQ) can promote the production of the nerve growth factor and has a protective effect on nerve injuries. The chemical kinetics of PQQ and DSer was studied by determining the free contents of PQQ using ion-pair liquid chromatography (LC), so it can provide important information for the mechanisms of PQQ in the regulation of neurotransmitter. The PQQ and the production of the incubation were separated on an Amethyst C18-P column using tetrabutylammonium bromide as ion-pair reagent. The average recoveries were between 94.2% and 99.3%, and the relative standard deviations were between 1.05% and 2.03%. The average rate constants (K) of PQQ with DSer were 0.032, 0.07 and 0.17 h(-1) at 25, 37 and 50 degrees C, respectively. The average activation energy (E(a)) was 54.7 kJ/mol. The values of half life (t1/2) were 22.0, 9.8 and 3.99 h at 25, 37 and 50 degrees C, respectively. The results showed that PQQ can regulate the balance of DSer in the brain. The method is simple and reliable. PMID:22679836

Zhou, Xingqin; Qin, Xiaofeng; Zhang, Jiankang; Cao, Guoxian

2012-02-01

377

Speciation of aluminum in rainwater using a fluoride ion-selective electrode and ion-exchange chromatography with fluorometric detection of the aluminum-lumogallion complex.  

PubMed

Soluble aluminum in rainwater was separated into three categories: free aluminum (Al3+), fluoride complexes (sum of AlF2+ and AlF2+), and other forms of aluminum. The free form of the aluminum ion (Al3+) was directly obtained from the separation data of aluminum species according to their charge using gradient elution cation-exchange chromatography. The aluminum fluoride complexes were estimated by combining the data of the free and total fluoride determined using a fluoride ion-selective electrode, with the assumption that 2+ charged aluminum species consisted only of AlF2+. The rest of the aluminum species had a 1+, neutral, or negative charge and mainly consisted of organic complexes. The origin of the organically bound aluminum is discussed. The concentration range of the total dissolved fluoride and aluminum in the rainwater samples was usually in the micromolar to submicromolar range, and the ratio of [T-F]/[T-Al] was found to be between 1 and 4. The speciation of dissolved aluminum into three categories was carried out on the basis of data of 15 rainwater samples collected in the city of Otsu. PMID:11816592

Hara, H; Kobayashi, H; Maeda, M; Ueno, A; Kobayashi, Y

2001-11-15

378

Tailored Noise Waveform\\/ Collision-Induced Dissociation of Ions Stored in a Linear Ion Trap Combined with Liquid Chromatography\\/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

Microsoft Academic Search

A new collision-induced dissociation (CID) technique based on broadband tailored noise waveform (TNW) excitation of ions stored in a linear ion trap has been developed. In comparison with the conventional sustained off-resonance irradiation (SORI) CID method commonly used in Fourier transform ion cyclotron resonance mass spectrometry, this MS\\/MS technique increases throughput by eliminating the long pump-down delay associated with gas

Andrey N. Vilkov; Bogdan Bogdanov; Liljiana Pasa-Tolic; David C. Prior; Gordon A. Anderson; Christophe D. Masselon; Ronald J. Moore; Richard D. Smith

2004-01-01

379

Capability measurement of size-exclusion chromatography with a light-scattering detection method in a stability study of bevacizumab using the process capability indices.  

PubMed

In this study, we investigated if the size-exclusion chromatography coupled with light-scattering and refractive index detection (SEC/LS/RI) method is fitted for its intended purpose and checked if the analytical method is able to provide enough conforming results. For this, the process capability indices Cp, Cpk, and Cpm were computed. The traditional X-chart and moving range (MR) chart were used by the same analyst to monitor the equipment in the laboratory over a 1-year period. For this, a bovine serum albumin (BSA) sample (0.3mgmL(-1)) with a nominal Mw of 66.4kDa was analyzed each working day. The results confirmed that the analytical method is in-control and stable. To determine whether the given process meets the present capability requirement and runs under the desired quality conditions, the Pearn and Shu (2003) method based on the lower confidence bound C on Cpm was used. The estimator Cpm was 1.81, and the lower confidence bound C was 1.40. We therefore conclude that the true value of the method capability Cpm is no less than 1.40 with a 95% level of confidence. This result indicates that the method is satisfactory and no stringent precision control is required. The usefulness of this method was applied in the characterization of bevacizumab commercial pharmaceutical preparations stored under different conditions that lead to aggregation. In this case, the computed Cpm index was 0.98 (0.70, 1.26), which indicates that the method does not comply with the specification limits and needs to be revised. The quality improvement effort should: (1) reduce the uncertainty in the absolute Mw determination; (2) either move the process mean closer to the target value or reduce the process variation, i.e. improve the method accuracy (?-T) and precision (?(2)). On this point, the Bayesian posterior distribution of the mean and standard deviation pointed out the need to control the precision but specially accuracy in order to reduce the overall uncertainty of analytical method and thus, the method is capable. PMID:24786652

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

2014-08-01

380

Development of a high performance size exclusion chromatography method to determine the stability of Human Serum Albumin in a lyophilized formulation of Interferon alfa-2b.  

PubMed

Intron Powder for Injection is a lyophilized formulation of Interferon alfa-2b marketed for treatment of Hepatitis C and some cancer indications. Human Serum Albumin (HSA) is used as a lyoprotectant and cryoprotectant at 1.0 mg/mL in the product formulation. No stability-indicating method, which can quantitate HSA and its dimer or oligomer aggregates in the formulated product, has been published to date. This paper describes the development and validation of a stability-indicating high performance size exclusion chromatography (HPSEC) method for the assay of HSA and estimation of HSA related compounds in lyophilized Intron Powder for Injection. The method employs a YMC-Pack Diol-200 column (7.8 mm x 30 cm, 5 microm porous particles with 250 A pore size), UV detection at 214 nm, and a mobile phase of 0.1 M phosphate buffer at pH 7.0 with 0.1 M sodium sulfate. The mobiles phase runs in an isocratic mode at 1.0 mL/min and the total chromatographic run time is 30 min. The method was validated for specific, linearity, accuracy, sensitivity, and robustness. It was shown to be specific for HSA and HSA aggregates (dimer and oligomers) with a limit of quantitation of 0.0005 mg/mL or 0.05% of HSA label claim in the presence of active therapeutic protein, Interferon alfa-2b, and the other pharmaceutical excipients, glycine, sodium phosphate dibasic, sodium phosphate monobasic. The method is stability indicating and is suitable for assay of HSA from 0.0005 mg/mL to 1.5mg/mL. (0.05-150% of HSA label claim) and for estimation of HSA related aggregates (dimer, and oligomer) from 0.0005 mg/mL to 0.15 mg/mL (0.05-15% of HSA label claim). The method is robust for routine use in product quality control. The method was applied to the analysis of batches of lyophilized Intron Powder for Injection of low, middle and high strength from the beginning, middle and end of shelf-life. The results indicated that HSA is stable in the product through out its shelf-life. PMID:18258245

Qian, Jin; Tang, Qinglin; Cronin, Bart; Markovich, Robert; Rustum, Abu

2008-06-13

381

Determination of the nitrogen content of nitrocellulose from smokeless gunpowders and collodions by alkaline hydrolysis and ion chromatography.  

PubMed

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

López-López, María; Alegre, Jose María Ramiro; García-Ruiz, Carmen; Torre, Mercedes

2011-01-31

382

Determination of glyphosate and phosphate in water by ion chromatography--inductively coupled plasma mass spectrometry detection.  

PubMed

Quantitative determination of trace glyphosate and phosphate in waters was achieved by coupling ion chromatography (IC) separation with inductively coupled plasma mass spectrometry (ICP-MS) detection. The separation of glyphosate and phosphate on a polymer anion-exchange column (Dionex IonPac AS16, 4.0 mm x 250 mm) was obtained by eluting them with 20 mM citric acid at 0.50 mL min(-1), and the analytes were detected directly and selectively by ICP-MS at m/z = 31. Parameters affecting their chromatographic behaviors and ICP-MS characteristics were systematically examined. Based on a 500-microL sample injection volume, the detection limits were 0.7 microgL(-1) for both glyphosate and phosphate, and the calibrations were linear up to 400 microgL(-1). Polyphosphates, aminomethylphosphonic acid (the major metabolite of glyphosate), non-polar and other polar phosphorus-containing pesticides showed different chromatographic behaviors from the analytes of interest and therefore did not interference. The determination was also interference free from the matrix anions (nitrate, nitrite, sulphate, chloride, etc.) and metallic ions. The analysis of certified reference material, drinking water, reservoir water and Newater yielded satisfactory results with spiked recoveries of 97.1-107.0% and relative standard deviations of < or = 7.4% (n = 3). Compared to other reported methods for glyphosate and phosphate, the developed IC-ICP-MS method is sensitive and simple, and does not require any chemical derivatization, sample preconcentration and mobile phase conductivity suppression. PMID:16185703

Guo, Zhong-Xian; Cai, Qiantao; Yang, Zhaoguang

2005-12-30

383

Matrix interference free determination of perchlorate in urine by ion association-ion chromatography-mass spectrometry.  

PubMed

Quantitative measurement of perchlorate in biological fluids is of importance to assess its toxicity and to study its effects on the thyroid gland. Whenever possible, urine samples are preferred in toxicologic/epidemiologic studies because sample collection is non-invasive. We present here a pretreatment method for the determination of perchlorate in urine samples that lead to a clean matrix. Urine samples, spiked with isotopically labeled perchlorate, are exposed to UV to destroy/decompose organic molecules and then sequentially treated with an H+-form cation exchange resin to remove protolyzable compounds, with ammonia to raise the pH to 10-11 and finally passed through a mini-column of basic alumina to remove the color and other organic matter. After filtration through a 0.45 microm syringe filter, the sample thus prepared can be directly injected into an ion chromatograph (IC). We use ion association-electrospray ionization-mass spectrometry (ESI-MS) to detect and quantify perchlorate. The proposed sample preparation method leads to excellent limits of detection (LOD's) for perchlorate since there is essentially no dilution of sample and the matrix effects are eliminated. Results of urine samples from both men and women volunteers are reported for perchlorate, as well as for iodide and thiocyanate, which are generally present at much higher concentrations and for which a "dilute and shoot" approach is adequate. The limit of detection (S/N=3) for iodide, thiocyanate and perchlorate by the present method was 0.40, 0.10 and 0.080 microg l(-1), respectively. PMID:17723382

Martinelango, P Kalyani; Gümü?, Gülçin; Dasgupta, Purnendu K

2006-05-10

384

Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.  

PubMed

A microfluidic membrane suppressor has been constructed to suppress ions of alkaline mobile-phases via an acid-base reaction across a sulfonated poly(tetrafluoroethylene)-based membrane and was evaluated for anion-exchange separations using conductivity detection. The membrane was clamped between two chip substrates, accommodating rectangular microchannels for the eluent and regenerant flow, respectively. Additionally, a clamp-on chip holder has been constructed which allows the alignment and stacking of different chip modules. The response and efficacy of the microfluidic chip suppressor was assessed for a wide range of eluent (KOH) concentrations, using 127 and 183?m thick membranes, while optimizing the flow rate and concentration of the regenerant solution (H2SO4). The optimal operating eluent flow rate was determined at 5?L/min, corresponding to the optimal van-Deemter flow velocity of commercially-available column technology, i.e. a 0.4mm i.d.×250mm long column packed with 7.5?m anion-exchange particles. When equilibrated at 10mM KOH, a 99% decrease in conductivity signal could be obtained within 5min when applying 10mM H2SO4 regenerant at 75?L/min. A background signal as low as 1.2?S/cm was obtained, which equals the performance of a commercially-available electrolytic hollow-fiber suppressor. When increasing the temperature of the membrane suppressor from 15 to 20°C, ion suppression was significantly improved allowing the application of 75mM KOH. The applicability of the chip suppressor has been demonstrated with an isocratic baseline separation of a mixture of seven inorganic ions, yielding plate numbers between 5300 and 10,600 and with a gradient separation of a complex ion mixture. PMID:24973803

Wouters, Sam; Wouters, Bert; Jespers, Sander; Desmet, Gert; Eghbali, Hamed; Bruggink, Cees; Eeltink, Sebastiaan

2014-08-15

385

Liquid chromatography coordination ion-spray mass spectrometry (LC–CIS–MS) of docosahexaenoate ester hydroperoxides  

Microsoft Academic Search

Coordination ion-spray mass spectrometry (CIS–MS) is a useful tool in the detection and identification of complex mixtures of cholesterol ester and phospholipid hydroperoxides. The methyl ester, cholesterol ester, and phospholipid hydroperoxides of docosahexaenoic acid were analyzed by LC–CIS–MS and their elution orders were identified. Their corresponding alcohols were also identified. The methyl hydroperoxydocosahexaenoate (HPDHE) elution order is 14, 17, 16,

Jennifer R. Seal; Ned A. Porter

2004-01-01

386

Ion-pair reversed-phase high-performance liquid chromatography analysis of oligonucleotides  

Microsoft Academic Search

An ion-pair reversed-phase HPLC method was evaluated for the separation of synthetic oligonucleotides. Mass transfer in the stationary phase was found to be a major factor contributing to peak broadening on porous C18 stationary phases. A small sorbent particle size (2.5 ?m), elevated temperature and a relatively slow flow-rate were utilized to enhance mass transfer. A short 50 mm column

Martin Gilar; Kenneth J. Fountain; Yeva Budman; Uwe D. Neue; Kurt R. Yardley; Paul D. Rainville; Reb J. Russell II; John C. Gebler

2002-01-01

387

Gas chromatography/ion mobility spectrometry as a hyphenated technique for improved explosives detection and analysis  

NASA Technical Reports Server (NTRS)

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.

Mercado, AL; Marsden, Paul

1995-01-01

388

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)

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.

Holland, P.; Chutjian, A.; Darrach, M.; Orient, O.

2002-01-01

389

Critical Evaluation of Acetylcholine Determination in Rat Brain Microdialysates using Ion-Pair Liquid Chromatography with Amperometric Detection  

PubMed Central

Liquid chromatography with amperometric detection remains the most widely used method for acetylcholine quantification in microdialysis samples. Separation of acetylcholine from choline and other matrix components on a microbore chromatographic column (1 mm internal diameter), conversion of acetylcholine in an immobilized enzyme reactor and detection of the produced hydrogen peroxide on a horseradish peroxidase redox polymer coated glassy carbon electrode, achieves sufficient sensitivity for acetylcholine quantification in rat brain microdialysates. However, a thourough validation within the concentration range required for this application has not been carried out before. Furthermore, a rapid degradation of the chromatographic columns and enzyme systems have been reported. In the present study an ion-pair liquid chromatography assay with amperometric detection was validated and its long-term stability evaluated. Working at pH 6.5 dramatically increased chromatographic stability without a loss in sensitivity compared to higher pH values. The lower limit of quantification of the method was 0.3 nM. At this concentration the repeatability was 15.7%, the inter-day precision 8.7% and the accuracy 103.6%. The chromatographic column was stable over 4 months, the immobilized enzyme reactor up to 2-3 months and the enzyme coating of the amperometric detector up to 1-2 months. The concentration of acetylcholine in 30 ?l microdialysates obtained under basal conditions from the hippocampus of freely moving rats was 0.40 ± 0.12 nM (mean ± SD, n = 30). The present method is therefore suitable for acetylcholine determination in rat brain microdialysates.

De Bundel, Dimitri; Sarre, Sophie; Van Eeckhaut, Ann; Smolders, Ilse; Michotte, Yvette

2008-01-01

390

Determination of berberine and palmatine in Phellodendri Cortex using ion-pair supercritical fluid chromatography on-line coupled with ion-pair supercritical fluid extraction by on-column trapping  

Microsoft Academic Search

An assay of berberine and palmatine in Phellodendri Cortex was established using ion-pair supercritical fluid chromatography (IP-SFC) on-line coupled with ion-pair supercritical fluid extraction (IP-SFE). The on-column method was employed to successfully perform on-line SFE-SFC. With a silica-gel column as a trapping and separation column, berberine and palmatine were extracted and focused at the column head, even if 10% methanol

Keiichi Suto; Shinichi Kakinuma; Yuji Ito; Kazuhiko Sagara; Hideki Iwasaki; Hideji Itokawa

1997-01-01

391

[Analysis of toxaphene and its eight congeners in sediment and fish tissue by gas chromatography-negative ion mass spectrometry].  

PubMed

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

Lao, Wenjian

2013-07-01

392

Characterization of steroid hormone receptors with ion-exchange fast protein liquid chromatography.  

PubMed

Androgen, estrogen and progesterone receptors have been characterized with anion exchange Fast Protein Liquid Chromatography (FPLC) on a Mono Q column (Pharmacia). In the presence of sodium molybdate androgen receptors in cytosols from rat prostate, rat epididymis and calf uterus eluted as a single sharp peak at 0.32 M NaCl with recoveries of approx 90%. The molybdate-stabilized form of the androgen receptor from rat prostate was purified about 75-fold. The receptor containing FPLC-peak fractions sedimented in high salt (0.4 M KCl) linear sucrose gradients at 3.6 S (prostate) and at 4.6 S (epididymis and calf uterus) respectively. Multiple forms of the androgen receptor were present in cytosols from rat prostate prepared in the absence of sodium molybdate, probably due to proteolytic breakdown of the native form. Calf uterine estradiol and progesterone receptors prepared in the presence of sodium molybdate (20 mM) eluted from the Mono Q column at 0.32 M NaCl. The molybdate-stabilized forms of the oestradiol and progesterone receptors were purified approx 70-fold and 30-fold respectively. In the absence of molybdate the estradiol receptor dissociated into two major forms eluting at 0.23 M NaCl and 0.37 M NaCl. After heat induced transformation (30 min at 25 degrees C) of the estradiol receptor one major peak was eluted at 0.42 M NaCl, indicating a change in the surface charge of the estradiol receptor as a result of the 4 S to 5 S transformation. It is concluded that the FPLC anion exchange system is a powerful, fast tool for characterization and partial purification of steroid receptors. In addition this technique could be applied as a rapid procedure for the quantitative estimation of steroid receptors in small biological samples. PMID:3871882

Brinkmann, A O; Bolt-de Vries, J; De Boer, W; Lindh, L M; Mulder, E; van der Molen, H J

1985-01-01

393

Determination of sodium, potassium, calcium and magnesium cations in biodiesel by ion chromatography.  

PubMed

This work reports an ion chromatographic (IC) method for the quantitative determination of inorganic cations (Na(+), K(+), Mg(2+) and Ca(2+)) in biodiesel samples that were synthesized from different vegetable oils and fat. The proposed method uses water extraction, heating and ultrasound. The limits of detection (LOD) for each ion, in milligrams of the analyte per kilogram of biodiesel (mgkg(-1)), were respectively: 0.11 (Na(+)); 0.42 (K(+)); 0.23 (Ca(2+)); and 0.36 (Mg(2+)). The accuracy of the method was studied through recovery tests. For comparison, two samples were also analyzed using an Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) procedure. The paired Student t test and the Snedecor F test showed that both methods offer equivalent results in terms of accuracy and precision. The operational simplicity, accuracy and precision of the proposed method suggest that it can be a good alternative for the determination of inorganic cations in biodiesel samples. PMID:22305906

de Caland, Lilia Basilio; Silveira, Eva Lúcia Cardoso; Tubino, Matthieu

2012-03-01

394

Liquid chromatography-electrospray quadrupole ion-trap mass spectrometry of nine pesticides in fruits.  

PubMed

A liquid chromatographic method, with electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS), has been developed for determining acrinathrin, carbosulfan, cyproconazole, lambda-cyhalothrin, kresoxim methyl, pyrifenox, pyriproxyfen, propanil, and tebufenpyrad in fruits. The ions prominent in ESI spectra were [M + H]+ and [M + Na]+. In the mass analyzer, collision-induced dissociation fragmentation involved common pathways, for example, product ions of [M + H]+ resulted from the cleavage of the carbamic group or an oxygen bound. The utility of the method is demonstrated by the analysis of crude extracts obtained by matrix solid-phase dispersion (MSPD) using C18 as dispersant and dichloromethane-methanol as eluent, and by solid-liquid extraction (SLE) with ethyl acetate and anhydrous sodium sulfate. Mean recoveries ranged from 51.5 to 108%, with relative standard deviations <16%, were obtained for MSPD and from 59 to 101% with relative standard deviation <17% for SLE. However, for most compounds, limits of quantification are better by SLE (0.01-4.4 mg kg(-1)) than by MSPD (0.05-2 mg kg(-1)). During the validation process, the procedure was tested for matrix effects, blanks and stability of the system. Considerably matrix effects in the ESI ionization process were detected by comparing standard calibration, and matrix calibration. Because of this, detected residues were quantified from interpolation against calibration data obtained using matrix matched standards. PMID:15453417

Soler, Carla; Mañes, Jordi; Picó, Yolanda

2004-09-01

395

[Simultaneous determination of twenty-one organic acids in food by ion chromatography with eluent autogeneration].  

PubMed

A novel ion chromatographic method was developed for the simultaneous determination of organic acids in food samples including quinic acid, acetic acid, pyruvic acid, ketosuccinic acid, mannitic acid, lactic acid, succinic acid, malic acid, tartaric acid, oxalic acid, fumaric acid, ascorbic acid, alpha-ketoglutaric acid, cinnamic acid, salicylic acid, citric acid, isocitric acid, ferulic acid, cis-aconitic acid, trans-aconitic acid, beta-coumaric acid. 5 - 34 mmol/L KOH produced by an EG40 eluent autogenerator could achieve a flat baseline and lower background conductance when performing gradient elution. The flow rate was 0.6 - 2.5 mL/min and the injection volume was 25 microL. The separation was performed on an IonPac AS11 column and detected by suppressed conductivity with self-regenerating suppressor mode. The samples were prepared through extraction, decoloration and filtration before analysis. Twenty-one organic acids showed good linear relationship between the mass concentration and the peak area in the measurement ranges. The correlation coefficients were above 0.999 and the detection limits were 0.011 - 0.188 mg/L, and the average recoveries were 91.5% - 101.8%. The method is simple and rapid with good accuracy and reproducibility, and has been applied to determine twenty-one organic acids in diversiform samples with satisfactory results. PMID:17432587

Lin, Huaying; Lin, Fenghua; Sheng, Lina; Li, Yidan; Zhang, Qiong

2007-01-01

396

Simultaneous determination of inorganic anions and cations in explosive residues by ion chromatography.  

PubMed

A non-suppressed ion chromatographic method by connecting anion-exchange and cation-exchange columns directly was developed for the separation and determination of five inorganic anions (sulfate, nitrate, chloride, nitrite, and chlorate) and three cations (sodium, ammonium, and potassium) simultaneously in explosive residues. The mobile phase was composed of 3.5mM phthalic acid with 2% acetonitrile and water at flow rate of 0.2 mL/min. Under the optimal conditions, the eight inorganic ions were completely separated and detected simultaneously within 16 min. The limits of detection (S/N=3) of the anions and cations were in the range of 50-100 microg/L and 150-320 microg/L, respectively, the linear correlation coefficients were 0.9941-0.9996, and the R.S.D. of retention time and peak area were 0.10-0.29% and 5.65-8.12%, respectively. The method was applied successfully to the analysis of the explosive samples with satisfactory results. PMID:18585271

Meng, Hong-Bo; Wang, Tian-Ran; Guo, Bao-Yuan; Hashi, Yuki; Guo, Can-Xiong; Lin, Jin-Ming

2008-07-15

397

Purification of monoclonal antibodies to Le(y) and Le(d) carbohydrate antigens by ion-exchange and thiophilic-adsorption chromatography.  

PubMed

The paper deals with convenient and fast methods for purification of monoclonal antibodies (MAbs) to carbohydrate antigens Le(y) and Le(d) from the cell culture and ascite fluid by ion-exchange chromatography on S-Sepharose and salt-promoted chromatography on a "thiophilic" adsorbent. One-step procedure on S-Sepharose of MAbs to Le(y) (IgG and IgM) provides significant purification (over 90% of contaminants were removed), while a purification factor for IgM to Le(d) is much lower. Highly purified IgM to Le(d) could be obtained by a two-step purification procedure including "thiophilic-adsorption" chromatography and gel-filtration (90-98% of contaminants from the cell culture and ascite fluid were removed). The preparations of IgG and IgM retain their initial antibody activity. PMID:7655191

Rapoport, E M; Zhigis, L S; Vlasova, E V; Piskarev, V E; Bovin, N V; Zubov, V P

1995-06-01

398

The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry  

SciTech Connect

The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

Johnson, S.

1999-02-12

399

[Determination of five halogenated acetic acids in water using ion chromatography].  

PubMed

The five halogenated acetic acids (HAAs), monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloro acetic acid (TCAA), monobromoacetic acid (MBAA), dibromoacetic acid (DBAA), were separated on an IonPac AS19 column specially designed for oxyhalides, and the separating conditions were optimized. DCAA and nitrite were separated by controlling the temperature. TCAA and sulfate were well separated rapidly by the concentration gradient of mobile phase. The interfering of carbonate (bicarbonate) was eliminated by the method of neutralization vacuum exhausting gas. The experimental results showed that the five HAAs, nitrite, bromide, nitrate, sulfate, etc. can be separated and detected simultaneously, and the detection limits of the DCAA and TCAA were 2.50 microg/L and 3.75 microg/L respectively, and the linearity ranges were from 10.0 to 2000.0 microg/L with the correlation coefficients of 0.999. The method is satisfied for the determination of drinking water. PMID:18438039

Gui, Jianye; Zhang, Lin

2008-01-01

400

Separation of sulfite, sulfate, and thiosulfate by ion chromatography with gradient elution  

SciTech Connect

A simple gradient apparatus, consisting of a peristaitic pump in addition to a standard high-pressure pump, is described. The device is used to make a single-run ion chromotographic separation of sulfite, sulfate, and thiosulfate in less than 15 min. This separation required a step gradient with 4.8 mM NaHCO/sub 3//4.7 mM Na/sub 2/CO/sub 3/ as start eluent and 6.9 mM NaHCO/sub 3//8.6 mM Na/sub 2/CO/sub 3/ is final eluent when two (4 x 50) mm Dionex anion precolumns in series were used as separator. The eluent compositions were simplex optimized.

Sunden, T. (Univ. of Umea, Sweden); Lindgren, M.; Cedergren, A.; Siemer, D.D.

1983-01-01

401

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching  

NASA Astrophysics Data System (ADS)

An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity ( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability (RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.

Du, Juan; Fa, Yun; Zheng, Yue; Li, Xuebing; Du, Fanglin; Yang, Haiyan

2014-05-01

402

Fragmentation of toxicologically relevant drugs in positive-ion liquid chromatography-tandem mass spectrometry.  

PubMed

The identification of drugs and related compounds by LC-MS-MS is an important analytical challenge in several application areas, including clinical and forensic toxicology, doping control analysis, and environmental analysis. Although target-compound based analytical strategies are most frequently applied, at some point the information content of the MS-MS spectra becomes relevant. In this article, the positive-ion MS-MS spectra of a wide variety of drugs and related substances are discussed. Starting point was an MS-MS mass spectral library of toxicologically relevant compounds, available on the internet. The positive-ion MS-MS spectra of ?570 compounds were interpreted by chemical and therapeutic class, thus involving a wide variety of drug compound classes, such benzodiazepines, beta-blockers, angiotensin-converting enzyme inhibitors, phenothiazines, dihydropyridine calcium channel blockers, diuretics, local anesthetics, vasodilators, as well as various subclasses of anti-diabetic, antidepressant, analgesic, and antihistaminic drugs. In addition, the scientific literature was searched for available MS-MS data of these compound classes and the interpretation thereof. The results of this elaborate study are presented in this article. For each individual compound class, the emphasis is on class-specific fragmentation, as discussing fragmentation of all individual compounds would take far too much space. The recognition of class-specific fragmentation may be quite informative in determining the compound class of a specific unknown, which may further help in the identification. In addition, knowledge on (class-specific) fragmentation may further help in the optimization of the selectivity in targeted analytical approaches of compounds of one particular class. PMID:21294151

Niessen, W M A

2011-01-01

403

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

PubMed

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

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

2013-12-01

404

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

PubMed

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

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

2011-04-01

405

Analysis of inorganic nitrogen and related anions in high salinity water using ion chromatography with tandem UV and conductivity detectors.  

PubMed

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

Wilson, Brian; Gandhi, Jay; Zhang, Chunlong Carl

2011-09-01

406

Development of a liquid chromatography-tandem mass spectrometry method for plasma-free metanephrines with ion-pairing turbulent flow online extraction.  

PubMed

Liquid chromatography-tandem mass spectrometry has become the preferred technology to measure unconjugated metanephrine and normetanephrine in plasma because of its high sensitivity and specificity over immunoassay and gas chromatography-mass spectrometry. In our earlier study, plasma metanephrines were extracted with offline ion-pairing solid-phase extraction and quantified by liquid chromatography-tandem mass spectrometry with porous graphitic carbon column based chromatography. In this study, we aim to automate the sample preparation with turbulent flow online extraction technology and maintain or improve the analytical performance previously achieved from the offline approach. The online extraction was done with a mixed-mode cation exchange turbulent flow chromatography column assisted with ion-pairing reagent and porous graphitic column was used for chromatographic separation. The total online extraction and analytical LC runtime was 12 min. This method was linear from 6.3 to 455.4 pg/mL for metanephrine; 12.6 to 954.5 pg/mL for normetanephrine with an accuracy of 80.6% to 93.5% and 80.9% to 101.7%, respectively. The lower limit of quantitation was 6.3 pg/mL for metanephrine and 12.6 pg/mL for normetanephrine. Inter-assay and intra-assay precision for metanephrine and normetanephrine at low and high concentration levels ranged from 2.0% to 10.5%. In conclusion, we have developed a fast and sensitive automated online turbulent flow extraction method for the quantitative analysis of plasma metanephrines. Ion-pairing reagent was necessary for the success of this method. PMID:22349327

He, Xiang; Kozak, Marta

2012-03-01

407

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

PubMed

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

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

2014-10-01

408

[Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography].  

PubMed

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

Yu, Ruipeng; Hu, Zhongyang; Ye, Mingli; Che, Jinshui

2012-04-01

409

Analysis of atmospheric aerosols by particle-induced X-ray emission, instrumental neutron activation analysis, and ion chromatography  

NASA Astrophysics Data System (ADS)

Particle-induced X-ray emission (PIXE), ion chromatography (IC), and occasionally also instrumental neutron activation analysis (INAA) were used in combination for the analysis of atmospheric aerosol samples that were collected on Nuclepore polycarbonate filters. A comparison of the results enabled us to evaluate the matrix effects (i.e., particle size effects) of the PIXE analysis for the light elements and to assess the water-solubility and/or speciation of a number of elements (e.g., S, K, Ca). Results are presented from several measurement campaigns at urban and forested sites in Europe, whereby PM10 or PM2.5 filter samples were taken. From the PIXE and IC results for a 2003 summer campaign at the K-puszta site in Hungary, it was estimated that organosulphates could be responsible for 20% of the total sulphur concentration and 30% of the organic aerosol in PM10. The comparison of the IC and PIXE data for K and Ca from the various sites indicated that most of the Ca was water-soluble (the mineral dust Ca was presumably mostly present as calcite, and perhaps also in part as gypsum); in contrast, for K, only half of it was typically water-soluble, indicating that it was to a large extent associated with insoluble mineral dust. Exceptions, with almost fully water-soluble K, were found for samples that were substantially impacted by biomass burning.

Maenhaut, Willy; Raes, Nico; Wang, Wan

2011-11-01

410

Derivatization Ion Chromatography for the Determination of Monoethanolamine in Presence of Hydrazine in PHWR Steam-Water Circuits.  

PubMed

A simple, rapid and accurate method for the determination of monoethanolamine (MEA) in PHWR steam-water circuits has been developed. MEA is added in the feed water to provide protection against corrosion while hydrazine is added to scavenge dissolved oxygen. The quantitative determination of MEA in presence of hydrazine was accomplished using derivatization ion chromatography with conductometric detection in nonsuppressed mode. A Metrosep cation 1-2 analytical column and a Metrosep cartridge were used for cation separation. A mixture of 4?mM tartaric acid, 20% acetone and 0.05?mM HNO(3) was used as eluent. Acetone in the mobile phase leads to the formation of different derivatives with MEA and hydrazine. The interferences due Na(+) and NH(4)?(+) were eliminated by adopting a simple pretreatment procedure employing OnGuard-H cartridge. The limit of detection limit of MEA was 0.1??g?mL(-1) and the relative standard deviation was 2% for the overall method. The recovery of MEA added was in the range 95%-102%. The method was applied to the determination of MEA in steam generator water samples. PMID:21785596

D, Ayushi; Sengupta, Arijit; Kumar, Sangita D; Kumbhar, A G; Venkateswaran, G

2011-01-01

411

[Fast screening of the artificial dyes in wine by liquid chromatography/hybrid linear ion trap-orbitrap mass spectrometry].  

PubMed

A fast screening method was established for the simultaneous determination of 15 water-soluble artificial dyes in wine by liquid chromatography/hybrid linear ion trap orbitrap mass spectrometry (LC/LTQ-orbitrap MS) based on a self-established mass spectral database. The confirmations of these target dyes were processed by the accurate mass numbers, and the MS(2) spectra marching to the self-established mass spectral database. The dyes in wine were purified by an anion-exchange column and separated by a BEH Phenyl column, then identified and quantified by LTQ-orbitrap MS. The results showed that the method detection limits of the target compounds were ranged from 0.00040 to 0.18 mg/L, and the average recoveries of the 15 compounds spiked at three concentrations were in the range of 43.1% - 127% with the relative standard deviations less than 10%. The spiked sample had the matching scores higher than 98% to the second order mass spectra of the standard compounds in the database. The method is also suitable for screening the 15 dyes in wine without reference standards. PMID:24369604

Li, Yongle; Zheng, Yanjie; Xiong, Cen; Zeng, Yongting; Chen, Sujuan

2013-08-01

412

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

PubMed

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

Rühmann, Broder; Schmid, Jochen; Sieber, Volker

2014-07-11

413

Determination of selenium and tellurium compounds in biological samples by ion chromatography dynamic reaction cell inductively coupled plasma mass spectrometry.  

PubMed

An ion chromatography-inductively coupled plasma mass spectrometric (IC-ICP-MS) method for the speciation of selenium and tellurium compounds namely selenite [Se(IV)], selenate [Se(VI)], Se-methylselenocysteine (MeSeCys), selenomethione (SeMet), tellurite [Te(IV)] and tellurate [Te(VI)] is described. Chromatographic separation is performed in gradient elution mode using 0.5 mmol L(-1) ammonium citrate in 2% methanol (pH 3.7) and 20 mmol L(-1) ammonium citrate in 2% methanol (pH 8.0). The analyses are carried out using dynamic reaction cell (DRC) ICP-MS. The DRC conditions have also been optimized to obtain interference free measurements of (78)Se(+) and (80)Se(+) which are otherwise interfered by (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+), respectively. The detection limits of the procedure are in the range 0.01-0.03 ng Se mL(-1) and 0.01-0.08 ng Te mL(-1), respectively. The accuracy of the method has been verified by comparing the sum of the concentrations of individual species obtained by the present procedure with the total concentration of the elements in two NIST SRMs Whole Milk Powder RM 8435 and Rice Flour SRM 1568a. The selenium and tellurium species are extracted from milk powder and rice flour samples by using Protease XIV at 70 degrees C on a water bath for 30 min. PMID:18199446

Kuo, Chia-Yi; Jiang, Shiuh-Jen

2008-02-15