Optimized anion exchange column isolation of zirconium-89 ( 89 Zr) from yttrium cyclotron target: Method development and implementation on an automated fluidic platform

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

O’Hara, Matthew J.; Murray, Nathaniel J.; Carter, Jennifer C.

Zirconium-89 (89Zr), produced by the (p,n) reaction from naturally monoisotopic yttrium (natY), is a promising positron emitting isotope for immunoPET imaging. Its long half-life of 78.4 h is sufficient for evaluating slow physiological processes. A prototype automated fluidic system, coupled to on-line and in-line detectors, has been constructed to facilitate development of new 89Zr purification methodologies. The highly reproducible reagent delivery platform and near-real time monitoring of column effluents allows for efficient method optimization. The separation of Zr from dissolved Y metal targets was evaluated using several anion exchange resins. Each resin was evaluated against its ability to quantitatively capturemore » Zr from a load solution that is high in dissolved Y. The most appropriate anion exchange resin for this application was identified, and the separation method was optimized. The method is capable of a high Y decontamination factor (>105) and has been shown to separate Fe, an abundant contaminant in Y foils, from the 89Zr elution fraction. Finally, the performance of the method was evaluated using cyclotron bombarded Y foil targets. The separation method was shown to achieve >95% recovery of the 89Zr present in the foils. The 89Zr eluent, however, was in a chemical matrix not immediately conducive to labeling onto proteins. The main intent of this study was to develop a tandem column 89Zr purification process, wherein the anion exchange column method described here is the first separation in a dual-column purification process.« less

Classification of LC columns based on the QSRR method and selectivity toward moclobemide and its metabolites.

PubMed

Plenis, Alina; Olędzka, Ilona; Bączek, Tomasz

2013-05-05

This paper focuses on a comparative study of the column classification system based on the quantitative structure-retention relationships (QSRR method) and column performance in real biomedical analysis. The assay was carried out for the LC separation of moclobemide and its metabolites in human plasma, using a set of 24 stationary phases. The QSRR models established for the studied stationary phases were compared with the column test performance results under two chemometric techniques - the principal component analysis (PCA) and the hierarchical clustering analysis (HCA). The study confirmed that the stationary phase classes found closely related by the QSRR approach yielded comparable separation for moclobemide and its metabolites. Therefore, the QSRR method could be considered supportive in the selection of a suitable column for the biomedical analysis offering the selection of similar or dissimilar columns with a relatively higher certainty. Copyright © 2013 Elsevier B.V. All rights reserved.

Industrial application of green chromatography--I. Separation and analysis of niacinamide in skincare creams using pure water as the mobile phase.

PubMed

Yang, Yu; Strickland, Zackary; Kapalavavi, Brahmam; Marple, Ronita; Gamsky, Chris

2011-03-15

In this work, chromatographic separation of niacin and niacinamide using pure water as the sole component in the mobile phase has been investigated. The separation and analysis of niacinamide have been optimized using three columns at different temperatures and various flow rates. Our results clearly demonstrate that separation and analysis of niacinamide from skincare products can be achieved using pure water as the eluent at 60°C on a Waters XTerra MS C18 column, a Waters XBridge C18 column, or at 80°C on a Hamilton PRP-1 column. The separation efficiency, quantification quality, and analysis time of this new method are at least comparable with those of the traditional HPLC methods. Compared with traditional HPLC, the major advantage of this newly developed green chromatography technique is the elimination of organic solvents required in the HPLC mobile phase. In addition, the pure water chromatography separations described in this work can be directly applied in industrial plant settings without further modification of the existing HPLC equipment. Copyright © 2011 Elsevier B.V. All rights reserved.

Proline-coated column for the capillary electrochromatographic separation of amino acids by in-column derivatization.

PubMed

Lin, Chun-Chi; Liu, Chuen-Ying

2004-10-01

With 3-trimethoxysilylpropyl chloride as the spacer, a proline-coated capillary column was prepared for the capillary electrochromatographic (CEC) separation of amino acids by in-column derivatization. Nine standard mixtures, including aspartic acid, glutamic acid, valine, phenylalanine, alanine, isoleucine, leucine, tyrosine, and tryptophan, were injected. o-Phthalaldehyde (OPA), OPA/2-mercaptoethanol (2-ME) and OPA/N-acetylcysteine (NAC) in borate buffer were tested as the derivatizing agent. Among them, OPA (50 mM) in borate buffer (pH 9.5, 50 mM) gave the best performance. The formation of isoindole could be detected by UV detection. The sandwich-type injection was carried out in hydrostatic mode (10 cm) with the program R(10 s)S(10 s) R(10 s)W(10 min) with R, S, and W being the reagent, sample, and waiting times. Mesityl oxide, benzyl alcohol, and acetone showed some interaction with the column. A current monitoring method was used instead of the determination of the electroosmotic flow (EOF). The direction of EOF was from anode to cathode even under acidic condition lower than the pI value (6.31) of the bonded group due to some unreacted silanol groups. Some parameters including pH, nature, and concentration of the mobile phase and the effect of organic modifier with regard to the CEC separation were investigated. With the proline-coated column (75 (50) cm x 75 microm ID) the best separation was performed in phosphate buffer (pH 4.00, 100 mM) with an applied voltage of -15 kV. The established method was also compared with those precolumn derivatized prior to the separation with proline-coated column as well as with in-capillary derivatization and separation with a bare fused-silica column. Copyright 2004 WILEY-VCH Verlag GmbH & Co.

The Application of TD/GC/NICI-MS with an Al2O3-PLOT-S Column for the Determination of Perfluoroalkylcycloalkanes in the Atmosphere.

PubMed

Ren, Yu; Schlager, Hans; Martin, Damien

2014-01-01

A modified method for the quantitative determination of atmospheric perfluoroalkylcycloalkanes (PFCs) using thermal desorption coupled with gas chromatography and detection by negative ion chemical ionization-mass spectrometry was developed. Using an optimized analytical system, a commercially available Al 2 O 3 porous layer open tubular (PLOT) capillary column (30 m × 0.25 mm) deactivated with Na 2 SO 4 was used for separation of PFCs. Improvements in the separation of PFCs, the corresponding identification and the limit of detection of PFCs using this method and column are presented. The method was successfully applied to determine the atmospheric background concentrations of a range of PFCs from a number of samples collected at a rural site in Germany. The results of this study suggest that the method outlined using the Al 2 O 3 -PLOT-S capillary column has good sensitivity and selectivity, and that it can be deployed in a routine laboratory process for the analysis of PFCs in the future research work. In addition, the ability of this column to separate the isomers of one of the lower boiling PFCs (perfluorodimethylcyclobutane) and its ability to resolve perfluoroethylcyclohexane offer the opportunity for single-column analysis for multiple PFCs.

Cu2+-imprinted cross-linked chitosan resin as micro-column packing materials for online chemiluminescence determination of trace copper.

PubMed

Nie, Feng; Hao, Liang; Gao, Mei; Wu, Yingchun; Li, Xinsheng; Yu, Sha

2011-01-01

The Cu(2+)-imprinted cross-linked chitosan resin was synthesized and the binding characteristic of the resin to Cu(2+) was evaluated. The prepared resin was packed into a micro-glass column and used as micro-separating column. The micro-separating column was connected into the chemiluminescence flow system and placed in front of the window of the photomultiplier tube. Based on the luminol-hydrogen peroxide chemiluminescence system, a flow injection online chemiluminescence method for determination of trace copper was developed and trace Cu(2+) in complex samples was successfully determined. The proposed method improved the shortcomings of chemiluminescence method's poor selectivity. Copyright © 2010 John Wiley & Sons, Ltd.

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

PubMed

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

2011-01-01

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

Counter-current motion in counter-current chromatography.

PubMed

Ito, Yoichiro

2014-12-12

After the CCC2012 meeting, I have received an e-mail regarding the terminology of "Countercurrent Chromatography". It stated that the term "Countercurrent" is a misnomer, because its stationary phase is motionless in the column and that the method should be renamed as liquid-liquid separations or centrifugal separations. However, it was found that these names are already used for various other techniques as found via Google search. The term "Countercurrent Chromatography" was originally made after two preparative methods of Countercurrent distribution and liquid Chromatography, both having no countercurrent motion in the column. However, it is surprising to find that this F1 hybrid method "Countercurrent Chromatography" can clearly exhibit countercurrent motion within the separation column in both hydrodynamic and hydrostatic equilibrium systems. This justifies that "Countercurrent Chromatography" is a proper term for this chromatographic method. Published by Elsevier B.V.

Clean-up of a pesticide-lanolin mixture by gel permeation chromatography.

PubMed

López-Mesas, M; Crespi, M; Brach, J; Mullender, J P

2000-12-01

In this study, the efficiency of a clean-up method by gel permeation chromatography (GPC) for the separation of pesticides from lanolin is analyzed. The pesticides analyzed belong to two different families, organophosphorous and synthetic pyrethroids. Lanolin, a standard mixture of the pesticides, and a lanolin-pesticides mixture are injected in a GPC column. The recoveries and elution times from the GPC column of lanolin (by a gravimetric method) and pesticides (by gas chromatography-electron capture detector) are determined. From this column, a good separation of the lanolin-pesticides mixture is observed.

Ionic liquids as stationary phases for fatty acid analysis by gas chromatography.

PubMed

Fanali, C; Micalizzi, G; Dugo, P; Mondello, L

2017-12-04

The present paper provides an overview of the application of ionic liquid (IL) columns for GC analysis of fatty acid methyl esters (FAMEs). Although their separation can be carried out utilizing GC columns containing polar stationary phases, some ILs have been employed as stationary phases, either commercial or laboratory made, in GC analysis. Monodimensional and bidimensional GC methods have been optimized in order to achieve the best separation especially considering the geometric and positional isomers of unsaturated fatty acids. Several methods for the analysis of trans-fatty acids have also been reported. The use of GC-GC, using either the same IL columns or different columns in the first and second dimensions, allowed the separation of a large number of FAMEs. The application of the IL columns for GC analysis of FAMEs in different types of real samples is described, e.g., oil of different nature (fish, flaxseed, and olive), margarine and butter, biodiesel, milk, bacteria etc.

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

NASA Astrophysics Data System (ADS)

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Final summarizing report on Grant DE-SC0001014 "Separation of Highly Complex Mixtures by Two-dimension Liquid Chromatography"

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

Guiochon, Georges

The goal of our research was a fundamental investigation of methods available for the coupling of two separate chromatographic separations that would considerably enhance the individual separation power of each of these two separations. This gain arises from the combination of two independent retention mechanisms, one of them separating the components that coelute on the other column, making possible the separation of many more compounds in a given time. The two separation mechanisms used must be very different. This is possible because many retention mechanisms are available, using different kinds of molecular interactions, hydrophobic or hydrophilic interactions, polar interactions, hydrogenmore » bonding, complex formation, ionic interactions, steric exclusion. Two methods can be used, allowing separations to be performed in space (spreading the bands of sample components on a plate covered with stationary phase layer) or in time (eluting the sample components through a column and detecting the bands leaving the column). Both offer a wide variety of possible combinations and were studied.« less

Application of a Fast Separation Method for Anti-diabetics in Pharmaceuticals Using Monolithic Column: Comparative Study With Silica Based C-18 Particle Packed Column.

PubMed

Hemdan, A; Abdel-Aziz, Omar

2018-04-01

Run time is a predominant factor in HPLC for quality control laboratories especially if there is large number of samples have to be analyzed. Working at high flow rates cannot be attained with silica based particle packed column due to elevated backpressure issues. The use of monolithic column as an alternative to traditional C-18 column was tested for fast separation of pharmaceuticals, where the results were very competitive. The performance comparison of both columns was tested for separation of anti-diabetic combination containing Metformin, Pioglitazone and Glimepiride using Gliclazide as an internal standard. Working at high flow rates with less significant backpressure was obtained with the monolithic column where the run time was reduced from 6 min in traditional column to only 1 min in monolithic column with accepted resolution. The structure of the monolith contains many pores which can adapt the high flow rate of the mobile phase. Moreover, peak symmetry and equilibration time were more efficient with monolithic column.

HPLC separation post-column reaction, UV-visible and fluorescence detection of trace UO/sub 2//sup 2 +//U/sup 4 +/ species in aqueous solutions

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

Karimi, A.R.

In this study a method for the measurement of uranium in natural waters at sub-ppB concentration levels by the separation and determination of U/sup 4 +/ and UO/sub 2//sup 2 +/ species is proposed. Reversed phase high performance liquid chromatography, followed by a post-column reaction and a sensitive UV-visible detection system was the method of choice to determine qualitatively and quantitatively the two uranium species. Also a cation-exchange and fluorescence detection system was studied for separation and determination of UO/sub 2//sup 2 +/ ions. Uranyl ion was selectively complexed with L-phenylalanine moetie in the sample solution containing U/sup 4 +/more » ions. Uranium (IV)/U(VI)-ligand was separated on a C/sub 18/ column with acetate buffer. Hexanesulfonate was found to be the choice for ion-pair reagent. The separation was best done with the acetate buffer at .01 M concentration and pH of 3.5. Absorption of the two species were measured after a post-column reaction with Arsenazo-III. Chromatographic parameters were calculated and a calibration curves were constructed. The detection limit for the procedure was 0.7 ..mu..g/mo and 1.2..mu..g/ml for U(IV) and U(VI) respectively. When U(VI) was separated on the cation-exchange column the limit of detection was calculated to be 1 ..mu..g/ml. The direct fluorometric method for U(VI) measurement results in a detection limit of 2 ppB and upper concentration limit of 2 ppM. The effect of interfering ions in the direct method of determination could be eliminated by dilution of sample solution.« less

SEPARATION OF T-MAZ ETHOXYLATED SORBITAN FATTY ACID ESTERS BY SUPERCRITICAL FLUID CHROMATOGRAPHY

EPA Science Inventory

The application of supercritical fluid chromatography (SFC) to the analysis of T-MAZ ethoxylated sorbitan fatty acid esters is described. FC separation methods utilize a density programming technique and a 50 um I.D. capillary column. his work demonstrates that capillary column S...

Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed-phase high-performance liquid chromatography.

PubMed

Zhang, Ping; Yu, Qian; He, Xiulong; Qian, Kun; Xiao, Wei; Xu, Zhifeng; Li, Tian; He, Lin

2018-04-01

The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum R s were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level. © 2017 Wiley Periodicals, Inc.

Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters

PubMed Central

Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz

2016-01-01

This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis. PMID:26805819

Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters.

PubMed

Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz

2016-01-21

This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.

Separation of the Components of a Commercial Analgesic Tablet: A Two-Week Sequence Comparing Purification by Two-Base Extraction and Column Chromatography

ERIC Educational Resources Information Center

Revell, Kevin D.

2011-01-01

A new laboratory experiment is described in which students compare two benchtop separation methods to isolate the three active components of the commercial analgesic Excedrin. In the two-week sequence, aspirin, acetaminophen, and caffeine are separated using either a two-base liquid-liquid extraction or silica column chromatography. Students then…

A Better Method for Filling Pasteur Pipet Chromatography Columns

ERIC Educational Resources Information Center

Ruekberg, Ben

2006-01-01

An alternative method for the preparation of Pasteur pipet chromatography columns is presented that allows the column to be filled with solvent without bubbles and allows greater control of fluid flow while the materials to be separated are added. Students are required to wear gloves and goggles and caution should be used while handling glass…

The separation of flavonoids from Pongamia pinnata using combination columns in high-speed counter-current chromatography with a three-phase solvent system.

PubMed

Yin, Hao; Zhang, Si; Long, Lijuan; Yin, Hang; Tian, Xinpeng; Luo, Xiongming; Nan, Haihan; He, Sha

2013-11-08

The mangrove plant Pongamia pinnata (Leguminosae) is well known as a plant pesticide. Previous studies have indicated that the flavonoids are responsible of the biological activities of the plant. A new high-speed counter-current chromatography (HSCCC) method for the separation of three flavonoids, karanjin (1), pinnatin (2), and pongaflavone (3), from P. pinnata was developed in the present study. The lower and intermediate phase (LP and IP) of a new three-phase solvent system, n-hexane-acetonitrile-dichloromethane-water, at a volume ratio of 5:5:1:5, were used as the stationary phases, while the upper phase (UP) was used as the mobile phase, and the volume ratio between the stationary phases in the CCC column could be tuned by varying the initial pumped volume ratio of the stationary phases. The CCC columns containing all three phases of the solvent system were considered combination columns. According to the theories of combination column, it is possible to optimize the retention time of the target compounds by varying the volume ratio of the stationary phases in the HSCCC combination columns, as well as the suitable volume ratios of the stationary phases for the separation of the target compounds were predicted from the partition coefficients of the compounds in the three-phase solvent system. Then, three HSCCC separations using the combination columns with initial pumped LP:IP volume ratios of 1:0, 0.9:0.1, and 0.7:0.3 were performed separately based on the prediction. Three target compounds were prepared with high purity when the initial pumped volume ratio of the stationary phases was 0.9:0.1. The baseline separation of compounds 2 and 3 was achieved on the combination column with an initial pumped volume ratio of 0.7:0.3. Furthermore, the three experiments clearly demonstrated that the retentions and resolutions of the target compounds increased with an increasing volume ratio of IP, which is consistent with the prediction for the retention times for the solutes on combination columns. The method proposed here reduces the need for solvent selection compared with the conventional method and may have broad potential applicability in the preparation of natural products. Copyright © 2013 Elsevier B.V. All rights reserved.

Isotopic generator for bismuth-212 and lead-212 based on radium

DOEpatents

Hines, J.J.; Atcher, R.W.; Friedman, A.M.

1985-01-30

Disclosed are method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

Isotopic generator for bismuth-212 and lead-212 from radium

DOEpatents

Atcher, Robert W.; Friedman, Arnold M.; Hines, John

1987-01-01

A method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

Enantioselective Analytical- and Preparative-Scale Separation of Hexabromocyclododecane Stereoisomers Using Packed Column Supercritical Fluid Chromatography.

PubMed

Riddell, Nicole; Mullin, Lauren Gayle; van Bavel, Bert; Ericson Jogsten, Ingrid; McAlees, Alan; Brazeau, Allison; Synnott, Scott; Lough, Alan; McCrindle, Robert; Chittim, Brock

2016-11-10

Hexabromocyclododecane (HBCDD) is an additive brominated flame retardant which has been listed in Annex A of the Stockholm Convention for elimination of production and use. It has been reported to persist in the environment and has the potential for enantiomer-specific degradation, accumulation, or both, making enantioselective analyses increasingly important. The six main stereoisomers of technical HBCDD (i.e., the (+) and (-) enantiomers of α-, β-, and γ-HBCDD) were separated and isolated for the first time using enantioselective packed column supercritical fluid chromatography (pSFC) separation methods on a preparative scale. Characterization was completed using published chiral liquid chromatography (LC) methods and elution profiles, as well as X-ray crystallography, and the isolated fractions were definitively identified. Additionally, the resolution of the enantiomers, along with two minor components of the technical product (δ- and ε-HBCDD), was investigated on an analytical scale using both LC and pSFC separation techniques, and changes in elution order were highlighted. Baseline separation of all HBCDD enantiomers was achieved by pSFC on an analytical scale using a cellulose-based column. The described method emphasizes the potential associated with pSFC as a green method of isolating and analyzing environmental contaminants of concern.

Chiral separation of G-type chemical warfare nerve agents via analytical supercritical fluid chromatography.

PubMed

Kasten, Shane A; Zulli, Steven; Jones, Jonathan L; Dephillipo, Thomas; Cerasoli, Douglas M

2014-12-01

Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G-type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical-scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(-) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(-) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents. © 2014 The Authors. Chirality published by John Wiley Periodicals, Inc.

Comprehensive two-dimensional chromatography with coupling of reversed phase high performance liquid chromatography and supercritical fluid chromatography.

PubMed

Stevenson, Paul G; Tarafder, Abhijit; Guiochon, Georges

2012-01-13

A 2D comprehensive chromatographic separation of blackberry sage fragrant oil was performed by using HPLC in the first dimension and SFC in the second. A C(18)-bonded silica column eluted with an ACN gradient was used in the HPLC dimension and an amino-bonded silica column eluted with ACN as a modifier in the SFC dimension. This 2D separation was completed in the off-line mode, the fractions from the HPLC column being collected and injected in the SFC column. The retention factors on the two columns have a -0.757 correlation coefficient. The method provides a practical peak capacity of 2400 in 280 min. The first eluted peaks in HPLC are the last ones eluted in SFC and vice versa. The results demonstrate that the coupling of an HPLC and an SFC separation have a great potential for 2D chromatographic separations. Copyright © 2011 Elsevier B.V. All rights reserved.

Group type analysis of asphalt by column liquid chromatography

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

Zhang, C.; Yang, J.; Xue, Y.

2008-07-01

An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The modelmore » compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.« less

Development of pseudo-linear gradient elution for high-throughput resin selectivity screening in RoboColumn® Format.

PubMed

Kiesewetter, André; Menstell, Peter; Peeck, Lars H; Stein, Andreas

2016-11-01

Rapid development of chromatographic processes relies on effective high-throughput screening (HTS) methods. This article describes the development of pseudo-linear gradient elution for resin selectivity screening using RoboColumns ® . It gives guidelines for the implementation of this HTS method on a Tecan Freedom EVO ® robotic platform, addressing fundamental aspects of scale down and liquid handling. The creation of a flexible script for buffer preparation and column operation plus efficient data processing provided the basis for this work. Based on the concept of discretization, linear gradient elution was transformed into multistep gradients. The impact of column size, flow rate, multistep gradient design, and fractionation scheme on separation efficiency was systematically investigated, using a ternary model protein mixture. We identified key parameters and defined optimal settings for effective column performance. For proof of concept, we examined the selectivity of several cation exchange resins using various buffer conditions. The final protocol enabled a clear differentiation of resin selectivity on miniature chromatography column (MCC) scale. Distinct differences in separation behavior of individual resins and the influence of buffer conditions could be demonstrated. Results obtained with the robotic platform were representative and consistent with data generated on a conventional chromatography system. A study on antibody monomer/high molecular weight separation comparing MCC and lab scale under higher loading conditions provided evidence of the applicability of the miniaturized approach to practically relevant feedstocks with challenging separation tasks as well as of the predictive quality for larger scale. A comparison of varying degrees of robotic method complexity with corresponding effort (analysis time and labware consumption) and output quality highlights tradeoffs to select a method appropriate for a given separation challenge or analytical constraints. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1503-1519, 2016. © 2016 American Institute of Chemical Engineers.

Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization.

PubMed

Wang, Jin Zhao; Zeng, Su; Hu, Gong Yun; Wang, Dan Hua

2009-04-10

SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm x 4.6 mm, 5 microm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.

Preparative electrophoresis of living lymphocytes

NASA Technical Reports Server (NTRS)

Vanoss, C. J.; Bigazzi, P. E.; Gillman, C. F.; Allen, R. E.

1974-01-01

Vertical liquid columns containing low molecular weight dextran density gradients can be used for preparative lymphocyte electrophoresis on earth, in simulation of 0 gravity conditions. Another method that has been tested at 1 G, is the electrophoresis of lymphocytes in a upward direction in vertical columns. By both methods up to 10 to the 7th power lymphocytes can be separated at one time in a 30 cm glass column of 8 mm inside diameter, at 12 v/cm, in 2 hours. Due to convection and sedimentation problems, the separation at 1 G is less than ideal, but it is expected that at 0 gravity electrophoresis will prove to be a uniquely powerful cell separation tool. The technical feasibility of electrophoresing inert particles at 0 G has been proven earlier, during the flight of Apollo 16.

Fast comprehensive two-dimensional gas chromatography method for fatty acid methyl ester separation and quantification using dual ionic liquid columns.

PubMed

Nosheen, Asia; Mitrevski, Blagoj; Bano, Asghari; Marriott, Philip J

2013-10-18

Safflower oil is a complex mixture of C18 saturated and unsaturated fatty acids amongst other fatty acids, and achieving separation between these similar structure components using one dimensional gas chromatography (GC) may be difficult. This investigation aims to obtain improved separation of fatty acid methyl esters in safflower oil, and their quantification using comprehensive two-dimensional GC (GC×GC). Here, GC×GC separation is accomplished by the coupling of two ionic liquid (IL) column phases: the combination of SLB-IL111 with IL59 column phases was finally selected since it provided excellent separation of a FAME standard mixture, as well as fatty acids in safflower and linseed oil, compared to other tested column sets. Safflower oil FAME were well separated in a short run of 16min. FAME validation was demonstrated by method reproducibility, linearity over a range up to 500mgL(-1), and limits of detection which ranged from 1.9mgL(-1) to 5.2mgL(-1) at a split ratio of 20:1. Quantification was carried out using two dilution levels of 200-fold for major components and 20-fold for trace components. The fatty acids C15:0 and C17:0 were not reported previously in safflower oil. The SLB-IL111/IL59 column set proved to be an effective and novel configuration for separation and quantification of vegetable and animal oil fatty acids. Copyright © 2013 Elsevier B.V. All rights reserved.

Validation of an HPLC method for the determination of fleroxacin and its photo-degradation products in pharmaceutical forms.

PubMed

Djurdjevic, Predrag; Laban, Aleksandra; Jelikic-Stankov, Milena

2004-01-01

HPLC determination of fleroxacin in dosage forms was carried out using either reversed-phase column YMC pack ODS-AQ or Supelco LC Hisep shielded hydrophobic phase column, with UV detection at 280 nm. The mobile phase for ODS column consisted of 50:50:0.5 v/v/v and for Hisep column 15:85:0.5 v/v/v acetonitrile-water-triethylamine. The pH of the mobile phase was adjusted to 6.30 for ODS column and to 6.85 for Hisep column, with H3PO4. Linear response was obtained in the concentration range of fleroxacin between 0.01 and 1.30 micrograms/mL. Detection limit was 4.8 ng/mL. Recovery test in the determination of fleroxacin in "Quinodis" tablets (Hoffmann La Roche, nominal mass 400 or 200 mg) was 98-101% for both columns. The effect of the composition and pH of the mobile phase on spectra, retention time and dissociation constants of fleroxacin was discussed. The proposed method could be also used for separation of the photo-degradation products of fleroxacin. Ten degradation products were separated on the ODS-AQ column, thus confirming the suitability of the proposed method for stability study of fleroxacin in pharmaceuticals.

A simple and inexpensive on-column frit fabrication method for fused-silica capillaries for increased capacity and versatility in LC-MS/MS applications.

PubMed

Wang, Ling-Chi; Okitsu, Cindy Yen; Kochounian, Harold; Rodriguez, Anthony; Hsieh, Chih-Lin; Zandi, Ebrahim

2008-05-01

A modified sol-gel method for a one-step on-column frit preparation for fused-silica capillaries and its utility for peptide separation in LC-MS/MS is described. This method is inexpensive, reproducible, and does not require specialized equipments. Because the frit fabrication process does not damage polyimide coating, the frit-fabricated column can be tightly connected on-line for high pressure LC. These columns can replace any capillary liquid transfer tubing without any specialized connections up-stream of a spray tip column. Therefore multiple columns with different phases can be connected in series for one- or multiple-dimensional chromatography.

Branched-chain dicationic ionic liquids for fatty acid methyl ester assessment by gas chromatography.

PubMed

Talebi, Mohsen; Patil, Rahul A; Sidisky, Leonard M; Berthod, Alain; Armstrong, Daniel W

2017-12-06

Twelve bis- or dicationic ionic liquids (ILs) including eight based on imidazolium, a single one based on phosphonium, and three based on pyrrolidinium cationic units were prepared with the bis(trifluoromethyl sulfonyl) imide anion. The two identical cationic moieties were attached by different alkyl spacers having three or five carbons and differing alkyl substituents attached to the spacer. The SLB-IL111 column, as the most polar commercial stationary phase known, was included in the study for comparison. Isothermal separations of a rapeseed oil fatty acid methyl ester (FAME) sample were used to study and compare the 12 IL-based column performances and selectivities. The retention times of the most retained methyl esters of lignoceric (C24:0) and erucic (C22:1) acids were used to estimate the IL polarity. The phosphonium dicationic IL column was, by far, the least polar. Imidazolium-based dicationic IL columns were the most polar. Polarity and selectivity for the FAME separation were somewhat related. The separation of a 37-FAME standard mixture allowed the investigation of selectivity variations observed on the 12 IL-based columns under temperature gradients up to 230 °C. The remarkable selectivity of the IL-based columns is demonstrated by the detailed analysis of the cis/trans C18:1 isomers of a partially hydrogenated vegetable oil sample on 30-m columns, separations competing with that done following an "official method" performed on a 100-m column. Graphical abstract Separation of fatty acid methyl esters on a 30-m 3m 2 C 5 (mpy) 2 . 2NTf 2 branched-chain dicationic IL-based column. Branched chain dicationic ILs show great selectivity for separation of cis/trans, ω-3/ω-6, and detailed analysis of cis/trans fats.

Simple, rapid, and environmentally friendly method for the separation of isoflavones using ultra-high performance supercritical fluid chromatography.

PubMed

Wu, Wenjie; Zhang, Yuan; Wu, Hanqiu; Zhou, Weie; Cheng, Yan; Li, Hongna; Zhang, Chuanbin; Li, Lulu; Huang, Ying; Zhang, Feng

2017-07-01

Isoflavones are natural substances that exhibit hormone-like pharmacological activities. The separation of isoflavones remains an analytical challenge because of their similar structures. We show that ultra-high performance supercritical fluid chromatography can be an appropriate tool to achieve the fast separation of 12 common dietary isoflavones. Among the five tested columns the Torus DEA column was found to be the most effective column for the separation of these isoflavones. The impact of individual parameters on the retention time and separation factor was evaluated. These parameters were optimized to develop a simple, rapid, and green method for the separation of the 12 target analytes. It only took 12.91 min using gradient elution with methanol as an organic modifier and formic acid as an additive. These isoflavones were determined with limit of quantitation ranging from 0.10 to 0.50 μg/mL, which was sufficient for reliable determination of various matrixes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

OPTIMIZATION AND VALIDATION OF HPLC METHOD FOR TETRAMETHRIN DETERMINATION IN HUMAN SHAMPOO FORMULATION.

PubMed

Zeric Stosic, Marina Z; Jaksic, Sandra M; Stojanov, Igor M; Apic, Jelena B; Ratajac, Radomir D

2016-11-01

High-performance liquid chromatography (HPLC) method with diode array detection (DAD) were optimized and validated for separation and determination of tetramethrin in an antiparasitic human shampoo. In order to optimize separation conditions, two different columns, different column oven temperatures, as well as mobile phase composition and ratio, were tested. Best separation was achieved on the Supelcosil TM LC-18- DB column (4.6 x 250 mm), particle size 5 jim, with mobile phase methanol : water (78 : 22, v/v) at a flow rate of 0.8 mL/min and at temperature of 30⁰C. The detection wavelength of the detector was set at 220 nm. Under the optimum chromatographic conditions, standard calibration curve was measured with good linearity [r2 = 0.9997]. Accuracy of the method defined as a mean recovery of tetramethrin from shampoo matrix was 100.09%. The advantages of this method are that it can easily be used for the routine analysis of drug tetramethrin in pharmaceutical formulas and in all pharmaceutical researches involving tetramethrin.

High-Throughput Analysis of Sucrose Fatty Acid Esters by Supercritical Fluid Chromatography/Tandem Mass Spectrometry

PubMed Central

Hori, Katsuhito; Tsumura, Kazunobu; Fukusaki, Eiichiro; Bamba, Takeshi

2014-01-01

Supercritical fluid chromatography (SFC) coupled with triple quadrupole mass spectrometry was applied to the profiling of sucrose fatty acid esters (SEs). The SFC conditions (column and modifier gradient) were optimized for the effective separation of SEs. In the column test, a silica gel reversed-phase column was selected. Then, the method was used for the detailed characterization of commercial SEs and the successful analysis of SEs containing different fatty acids. The present method allowed for fast and high-resolution separation of monoesters to tetra-esters within a shorter time (15 min) as compared to the conventional high-performance liquid chromatography. The applicability of our method for the analysis of SEs was thus demonstrated. PMID:26819875

[Determination of sennosides and degraded products in the process of sennoside metabolism by HPLC].

PubMed

Sun, Yan; Li, Xuetuo; Yu, Xingju

2004-01-01

A method for the separation and determination of sennosides A and B and the main composition (sennidins A and B) in degraded products of sennosides by linear gradient high performance liquid chromatography has been developed. Separation conditions were as follows: column, a Spherisorb C18 column (250 mm x 4.6 mm i.d., 10 microm); column temperature, 40 degrees C; detection wavelength, 360 nm; mobile phase A, 1.25% acetic acid aqueous solution; mobile phase B, methanol; linear gradient, 100% A --> (20 min) 100% B. The method is effective, quick, accurate and reproducible. The satisfactory results show that this new method has certain practical values as an approach of real-time analysis in the process of sennoside metabolism.

Evaluation of an International Pharmacopoeia method for the analysis of nelfinavir mesilate by liquid chromatography.

PubMed

Yekkala, Raja Satyanarayana; Vandenwayenberg, Stephanie; Hoogmartens, Jos; Adams, Erwin

2006-11-17

A gradient LC method for the determination of related substances in nelfinavir mesilate (NFVM) has been recently published in the International Pharmacopoeia. The method uses a base deactivated reversed phase C18 column (25 cm x 4.6 mm I.D.), 5 microm kept at a temperature of 35 degrees C. The mobile phases consist of acetonitrile, methanol, phosphate buffer pH 3.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 225 nm. A system suitability test (SST) is described to govern the quality of the separation. The separation towards NFVM components was investigated on 18 C18 columns and correlation was made with the column classification system developed in our laboratory. The method was evaluated using a Hypersil BDS C18 column (25 cm x 4.6 mm I.D.), 5 microm. A two level fractional factorial design was applied to examine the robustness of the method. The method shows good selectivity, precision, linearity and sensitivity. Seven commercial samples were examined using this method.

Enhanced capabilities of separation in Sequential Injection Chromatography--fused-core particle column and its comparison with narrow-bore monolithic column.

PubMed

Chocholouš, Petr; Kosařová, Lucie; Satínský, Dalibor; Sklenářová, Hana; Solich, Petr

2011-08-15

In the Sequential Injection Chromatography (SIC) only monolithic columns for chromatographic separations have been used so far. This article presents the first use of fused-core particle packed column in an attempt to extend of the chromatographic capabilities of the SIC system. A new fused-core particle column (2.7 μm) Ascentis(®) Express C18 (Supelco™ Analytical) 30 mm × 4.6 mm brings high separation efficiency within flow rates and pressures comparable to monolithic column Chromolith(®) Performance RP-18e 100-3 (Merck(®)) 100 mm × 3 mm. Both columns matches the conditions of the commercially produced SIC system - SIChrom™ (8-port high-pressure selection valve and medium-pressure Sapphire™ syringe pump with 4 mL reservoir - maximal work pressure 1000 PSI) (FIAlab(®), USA). The system was tested by the separation of four estrogens with similar structure and an internal standard - ethylparaben. The mobile phase composed of acetonitrile/water (40/60 (v/v)) was pumped isocratic at flow rate 0.48 mL min(-1). Spectrophotometric detection was performed at wavelength of 225 nm and injected volume of sample solutions was 10 μL. The chromatographic characteristics of both columns were compared. Obtained results and conclusions have shown that both fused-core particle column and longer narrow shaped monolithic column bring benefits into the SIC method. Copyright © 2011 Elsevier B.V. All rights reserved.

Optimal performance of single-column chromatography and simulated moving bed processes for the separation of optical isomers

NASA Astrophysics Data System (ADS)

Medi, Bijan; Kazi, Monzure-Khoda; Amanullah, Mohammad

2013-06-01

Chromatography has been established as the method of choice for the separation and purification of optically pure drugs which has a market size of about 250 billion USD. Single column chromatography (SCC) is commonly used in the development and testing phase of drug development while multi-column Simulated Moving Bed (SMB) chromatography is more suitable for large scale production due to its continuous nature. In this study, optimal performance of SCC and SMB processes for the separation of optical isomers under linear and overloaded separation conditions has been investigated. The performance indicators, namely productivity and desorbent requirement have been compared under geometric similarity for the separation of a mixture of guaifenesin, and Tröger's base enantiomers. SCC process has been analyzed under equilibrium assumption i.e., assuming infinite column efficiency, and zero dispersion, and its optimal performance parameters are compared with the optimal prediction of an SMB process by triangle theory. Simulation results obtained using actual experimental data indicate that SCC may compete with SMB in terms of productivity depending on the molecules to be separated. Besides, insights into the process performances in terms of degree of freedom and relationship between the optimal operating point and solubility limit of the optical isomers have been ascertained. This investigation enables appropriate selection of single or multi-column chromatographic processes based on column packing properties and isotherm parameters.

The study on the extraction method of indirubin from Indigo Naturalis.

PubMed

Cheng, Li-hui

2007-01-01

To discuss how to extract the indirubin of the higher purity from Indigo Naturalis. After extracting the indirubin from Indigo Naturalis by acetic ether, compare the separation effect of the extract in Si gel column with that in alumina column. The indirubin in Indigo Naturalis by Si gel column chromatography is chosen. The purity of indirubin is 98.3% after Si gel column chromatography. The indiruhbin of the higher purity was attained by the simple experimental method.

Hybridation of different chiral separation techniques with ICP-MS detection for the separation and determination of selenomethionine enantiomers: chiral speciation of selenized yeast.

PubMed

Méndez, S P; González, E B; Sanz-Medel, A

2001-05-01

Enantioseparation and determination of selenomethionine enantiomers in selenized yeast was investigated using chiral separation techniques based on different principles, coupled on-line to inductively coupled plasma mass spectrometry (ICP-MS) for selenium-specific detection. High performance liquid chromatography (HPLC) on a beta-cyclodestrin (beta-CD) column, cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC), gas chromatography (GC) on a Chirasil-L-Val column, and HPLC on a Chirobiotic T column have been investigated as the chiral separation techniques. For HPLC separation on the beta-CD column, and also for CD-MEKC, selenomethionine enantiomers were derivatized with NDA/CN(-). For chiral separation by GC, selenomethionine enantiomers were converted into their N-trifluoroacetyl (TFA)-O-alkyl esters. The developed hybridation methodologies are compared with respect to enantioselectivity, sensitivity and analysis time. The usefulness of the best-suited method [HPLC (Chirobiotic T)-ICP-MS] was demonstrated by its application to the successful chiral speciation of selenium and D-and L-selenomethionine content determination in selenized yeast. Copyright 2001 John Wiley & Sons, Ltd.

Chiral separation of the β2-sympathomimetic fenoterol by HPLC and capillary zone electrophoresis for pharmacokinetic studies.

PubMed

Ullrich, Thomas; Wesenberg, Dirk; Bleuel, Corinna; Krauss, Gerd-Joachim; Schmid, Martin G; Weiss, Michael; Gübitz, Gerald

2010-10-01

The development of methods for the separation of the enantiomers of fenoterol by chiral HPLC and capillary zone electrophoresis (CZE) is described. For the HPLC separation precolumn fluorescence derivatization with naphthyl isocyanate was applied. The resulting urea derivatives were resolved on a cellulose tris(3,5-dimethylphenylcarbamate)-coated silica gel column employing a column switching procedure. Detection was carried out fluorimetrically with a detection limit in the low ng/mL range. The method was adapted to the determination of fenoterol enantiomers in rat heart perfusates using liquid-liquid extraction. As an alternative a CE method was used for the direct separation of fenoterol enantiomers comparing different cyclodextrin derivatives as chiral selectors. Copyright © 2010 John Wiley & Sons, Ltd.

Chiral Separation of G-type Chemical Warfare Nerve Agents via Analytical Supercritical Fluid Chromatography

PubMed Central

Kasten, Shane A; Zulli, Steven; Jones, Jonathan L; Dephillipo, Thomas; Cerasoli, Douglas M

2014-01-01

Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G-type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical-scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(–) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(–) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents. Chirality 26:817–824, 2014. © 2014 The Authors. Chirality published by John Wiley Periodicals, Inc. PMID:25298066

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

PubMed Central

Heshka, Nicole E.; Hager, Darcy B.

2015-01-01

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate interferences, a two dimensional column configuration is used, with a Deans switch employed to transfer hydrogen sulfide from the first to the second column (heart-cutting). Liquid crude samples are first separated on a dimethylpolysiloxane column, and light gases are heart-cut and further separated on a bonded porous layer open tubular (PLOT) column that is able to separate hydrogen sulfide from other light sulfur species. Hydrogen sulfide is then detected with a sulfur chemiluminescence detector, adding an additional layer of selectivity. Following separation and detection of hydrogen sulfide, the system is backflushed to remove the high-boiling hydrocarbons present in the crude samples and to preserve chromatographic integrity. Dissolved hydrogen sulfide has been quantified in liquid samples from 1.1 to 500 ppm, demonstrating wide applicability to a range of samples. The method has also been successfully applied for the analysis of gas samples from crude oil headspace and process gas bags, with measurement from 0.7 to 9,700 ppm hydrogen sulfide. PMID:26709594

Trace analysis of impurities in bulk gases by gas chromatography-pulsed discharge helium ionization detection with "heart-cutting" technique.

PubMed

Weijun, Yao

2007-10-12

A method has been developed for the detection of low-nL/L-level impurities in bulk gases such as H(2), O(2), Ar, N(2), He, methane, ethylene and propylene, respectively. The solution presented here is based upon gas chromatography-pulsed discharge helium ionization detection (GC-PDHID) coupled with three two-position valves, one two-way solenoid valve and four packed columns. During the operation, the moisture and heavy compounds are first back-flushed via a pre-column. Then the trace impurities (except CO(2) which is diverted to a separate analytical column for separation and detection) together with the matrix enter onto a main column, followed by the heart-cut of the impurities onto a longer analytical column for complete separation. Finally the detection is performed by PDHID. This method has been applied to different bulk gases and the applicability of detecting impurities in H(2), Ar, and N(2) are herewith demonstrated. As an example, the resulting detection limit of 100 nL/L and a dynamic range of 100-1000 nL/L have been obtained using an Ar sample containing methane.

Determination of ambroxol hydrochloride, methylparaben and benzoic acid in pharmaceutical preparations based on sequential injection technique coupled with monolithic column.

PubMed

Satínský, Dalibor; Huclová, Jitka; Ferreira, Raquel L C; Montenegro, Maria Conceição B S M; Solich, Petr

2006-02-13

The porous monolithic columns show high performance at relatively low pressure. The coupling of short monoliths with sequential injection technique (SIA) results in a new approach to implementation of separation step to non-separation low-pressure method. In this contribution, a new separation method for simultaneous determination of ambroxol, methylparaben and benzoic acid was developed based on a novel reversed-phase sequential injection chromatography (SIC) technique with UV detection. A Chromolith SpeedROD RP-18e, 50-4.6 mm column with 10 mm precolumn and a FIAlab 3000 system with a six-port selection valve and 5 ml syringe were used for sequential injection chromatographic separations in our study. The mobile phase used was acetonitrile-tetrahydrofuran-0.05M acetic acid (10:10:90, v/v/v), pH 3.75 adjusted with triethylamine, flow rate 0.48 mlmin(-1), UV-detection was at 245 nm. The analysis time was <11 min. A new SIC method was validated and compared with HPLC. The method was found to be useful for the routine analysis of the active compounds ambroxol and preservatives (methylparaben or benzoic acid) in various pharmaceutical syrups and drops.

Rapid column heating method for subcritical water chromatography.

PubMed

Fogwill, Michael O; Thurbide, Kevin B

2007-01-19

A novel resistive heating method is presented for subcritical water chromatography (SWC) that provides higher column heating rates than those conventionally obtained from temperature-programmed gas chromatography (GC) convection ovens. Since the polarity of water reduces dramatically with increasing temperature, SWC employs column heating to achieve gradient elution. As such, the rate at which the mobile phase is heated directly impacts the magnitude of such gradients applied in SWC. Data from the current study demonstrate that the maximum column heating rate attainable in a typical SWC apparatus (i.e. using a GC convection oven) is around 10 degrees C/min, even at instrument oven settings of over three times this value. Conversely, by wrapping the separation column with ceramic insulation and a resistively heated wire, the column heating rates are increased five-fold. As a result, elution times can be greatly decreased in SWC employing gradients. Separations of standard alcohol test mixtures demonstrate that the retention time of the latest eluting component decreases by 35 to 50% using the prototype method. Additionally, solute retention times in this mode deviate by less than 1% RSD over several trials, which compares very well to those obtained using a conventional GC convection oven. Results suggest that the developed method can be a useful alternative heating technique in SWC.

Very high pressure liquid chromatography using core-shell particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois A; Guiochon, Georges

2014-01-17

Five methods for controlling the mobile phase flow rate for gradient elution analyses using very high pressure liquid chromatography (VHPLC) were tested to determine thermal stability of the column during rapid gradient separations. To obtain rapid separations, instruments are operated at high flow rates and high inlet pressure leading to uneven thermal effects across columns and additional time needed to restore thermal equilibrium between successive analyses. The purpose of this study is to investigate means to minimize thermal instability and obtain reliable results by measuring the reproducibility of the results of six replicate gradient separations of a nine component RPLC standard mixture under various experimental conditions with no post-run times. Gradient separations under different conditions were performed: constant flow rates, two sets of constant pressure operation, programmed flow constant pressure operation, and conditions which theoretically should yield a constant net heat loss at the column's wall. The results show that using constant flow rates, programmed flow constant pressures, and constant heat loss at the column's wall all provide reproducible separations. However, performing separations using a high constant pressure with programmed flow reduces the analysis time by 16% compared to constant flow rate methods. For the constant flow rate, programmed flow constant pressure, and constant wall heat experiments no equilibration time (post-run time) was required to obtain highly reproducible data. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation of sunscreens in skincare creams using greener high-temperature liquid chromatography and subcritical water chromatography.

PubMed

Kapalavavi, B; Marple, R; Gamsky, C; Yang, Y

2012-04-01

In this study, high-temperature liquid chromatographic (HTLC) and subcritical water chromatographic (SBWC) separations of sunscreens contained in skincare creams were achieved at temperatures ranging from 90 to 250°C. The columns employed in this work include a ZirChrom-DiamondBond-C18, a XTerra MS C18 and a XBridge C18 column. The quantity of methanol consumed by the greener HTLC sunscreen methods developed in this project is significantly reduced although the HTLC separation at this stage is not as efficient as that achieved by traditional HPLC. SBWC separation of sunscreens was also achieved on the XTerra MS C18 and the XBridge C18 columns using pure water at 230-250°C. Methanol was eliminated in the SBWC methods developed in this study. © 2011 The Authors. ICS © 2011 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Simultaneous separation of water- and fat-soluble vitamins in isocratic pressure-assisted capillary electrochromatography using a methacrylate-based monolithic column.

PubMed

Yamada, Hiroki; Kitagawa, Shinya; Ohtani, Hajime

2013-06-01

A method of simultaneous separation of water- and fat-soluble vitamins using pressure-assisted CEC with a methacrylate-based capillary monolithic column was developed. In the proposed method, water-soluble vitamins were mainly separated electrophoretically, while fat soluble-ones were separated chromatographically by the interaction with a methacrylate-based monolith. A mixture of six water-soluble and four fat-soluble vitamins was separated simultaneously within 20 min with an isocratic elution using 1 M formic acid (pH 1.9)/acetonitrile (30:70, v/v) containing 10 mM ammonium formate as a mobile phase. When the method was applied to a commercial multivitamin tablet and a spiked one, the vitamins were successfully analyzed, and no influence of the matrix contained in the tablet was observed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A new method for the preparation of polymeric porous layer open tubular columns for GC application

NASA Technical Reports Server (NTRS)

Shen, T. C.; Wang, M. L.

1995-01-01

A new method to prepare polymeric PLOT columns by using in situ polymerization technology is described. The method involves a straightforward in situ polymerization of the monomer. The polymer produced is directly coated on the metal tubing. This eliminates many of the steps needed in conventional polymeric PLOT column preparation. Our method is easy to operate and produces very reproducible columns, as shown previously (T. C. Shen. J. Chromatogr. Sci. 30, 239, 1992). The effects of solvents, tubing pretreatments, initiators and reaction temperatures in the preparation of PLOT columns are studied. Several columns have been developed to separate (1) highly polar compounds, such as water and ammonia or water and HCN, and (2) hydrocarbons and inert gases. A recent improvement has allowed us to produce bonded polymeric PLOT columns. These were studied, and the results are included also.

Separation of alpha-, beta-, gamma-, delta-tocopherols and alpha-tocopherol acetate on a pentaerythritol diacrylate monostearate-ethylene dimethacrylate monolith by capillary electrochromatography.

PubMed

Chaisuwan, Patcharin; Nacapricha, Duangjai; Wilairat, Prapin; Jiang, Zhengjin; Smith, Norman W

2008-06-01

This work reports the first use of a monolith with method development for the separation of tocopherol (TOH) compounds by CEC with UV detection. A pentaerythritol diacrylate monostearate-ethylene dimethacrylate (PEDAS-EDMA) monolithic column has been investigated for an optimised condition to separate alpha-, beta-, gamma- and delta-TOHs, and alpha-tocopherol acetate (TAc). The PEDAS-EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the beta- and gamma-isomers which are not easily separated by standard C8 or C18 particle-packed columns. Retention studies indicated that an RP mechanism was involved in the separation on the PEDAS-EDMA column, but polar interactions with the underlying ester and hydroxyl groups enhanced the separation of the problematic beta- and gamma-isomers. Separation of all the compounds was achieved within 25 min using 3:10:87 v/v/v 100 mM Tris buffer (pH 9.3)/methanol/ACN as the mobile phase. The method was successfully applied to a pharmaceutical sample with recoveries from 93 to 99%. Intraday and interday precisions (%RSD) for peak area and retention time were less than 2.3. LODs for all four TOHs and TAc were below 1 ppm.

A PROCESS FOR SEPARATING AZEOTROPIC MIXTURES BY EXTRACTIVE AND CONVECTIVE DISTILLATION

DOEpatents

Frazer, J.W.

1961-12-19

A method is described for separating an azeotrope of carbon tetrachloride and 1,1,2,2-tetrafluorodinitroethane boiling at 60 deg C. The ndethod comnprises, specifically, feeding azeotrope vapors admixed with a non- reactive gas into an extractive distillation column heated to a temperature preferably somewhat above the boiling point of the constant boiling mixture. A solvent, di-n-butylphthalate, is metered into the column above the gas inlet and permitted to flow downward, earrying with it the higher bomling fraction, while the constituent having the lower boiling point passes out of the top of the column with the non-reactive gas and is collected in a nitrogen cold trap. Other solvents which alter the vapor pressure relationship may be substituted. The method is generally applicable to azeotropic mixtures. A number of specific mixtures whicb may be separated are disclosed. (AEC)

Determination of antioxidants by a novel on-line HPLC-cupric reducing antioxidant capacity (CUPRAC) assay with post-column detection.

PubMed

Celik, Saliha Esin; Ozyürek, Mustafa; Güçlü, Kubilay; Apak, Reşat

2010-07-26

A novel on-line HPLC-cupric reducing antioxidant capacity (CUPRAC) method was developed for the selective determination of polyphenols (flavonoids, simple phenolic and hydroxycinnamic acids) in complex plant matrices. The method combines chromatographic separation, constituent analysis, and post-column identification of antioxidants in plant extracts. The separation of polyphenols was performed on a C18 column using gradient elution with two different mobile phase solutions, i.e., MeOH and 0.2% o-phosphoric acid. The HPLC-separated antioxidant polyphenols in the extracts react with copper(II)-neocuproine (Cu(II)-Nc) reagent in a post-column reaction coil to form a derivative. The reagent is reduced by antioxidants to the copper(I)-neocuproine (Cu(I)-Nc) chelate having maximum absorption at 450 nm. The negative peaks of antioxidant constituents were monitored by measuring the increase in absorbance due to Cu(I)-Nc. The detection limits of polyphenols at 450 nm (in the range of 0.17-3.46 microM) after post-column derivatization were comparable to those at 280 nm UV detection without derivatization. The developed method was successfully applied to the identification of antioxidant compounds in crude extracts of Camellia sinensis, Origanum marjorana and Mentha. The method is rapid, inexpensive, versatile, non-laborious, uses stable reagents, and enables the on-line qualitative and quantitative estimation of antioxidant constituents of complex plant samples. Copyright 2010 Elsevier B.V. All rights reserved.

Development and application of a high-performance liquid chromatography method using monolithic columns for the analysis of ecstasy tablets.

PubMed

Mc Fadden, Kim; Gillespie, John; Carney, Brian; O'Driscoll, Daniel

2006-07-07

A rapid and selective HPLC method using monolithic columns was developed for the separation and quantification of the principal amphetamines in ecstasy tablets. Three monolithic (Chromolith RP18e) columns of different lengths (25, 50 and 100 mm) were assessed. Validation studies including linearity, selectivity, precision, accuracy and limit of detection and quantification were carried out using the Chromolith SpeedROD, RP-18e, 50 mm x 4.6 mm column. Column backpressure and van Deemter plots demonstrated that monolithic columns provide higher efficiency at higher flow rates when compared to particulate columns without the loss of peak resolution. Application of the monolithic column to a large number of ecstasy tablets seized in Ireland ensured its suitability for the routine analysis of ecstasy tablets.

Transport of Cryptosporidium parvum Oocysts in Soil Columns following Applications of Raw and Separated Liquid Slurries

PubMed Central

Petersen, Heidi H.; Enemark, Heidi L.; Olsen, Annette; Amin, M. G. Mostofa

2012-01-01

The potential for the transport of viable Cryptosporidium parvum oocysts through soil to land drains and groundwater was studied using simulated rainfall and intact soil columns which were applied raw slurry or separated liquid slurry. Following irrigation and weekly samplings over a 4-week period, C. parvum oocysts were detected from all soil columns regardless of slurry type and application method, although recovery rates were low (<1%). Soil columns with injected liquid slurry leached 73 and 90% more oocysts compared to columns with injected and surface-applied raw slurries, respectively. Among leachate samples containing oocysts, 44/72 samples yielded viable oocysts as determined by a dye permeability assay (DAPI [4′,6′-diamidino-2-phenylindole]/propidium iodide) with the majority (41%) of viable oocysts found in leachate from soil columns with added liquid slurry. The number of viable oocysts was positively correlated (r = 0.63) with the total number of oocysts found. Destructively sampling of the soil columns showed that type of slurry and irrigation played a role in the vertical distribution of oocysts, with more oocysts recovered from soil columns added liquid slurry irrespective of the irrigation status. Further studies are needed to determine the effectiveness of different slurry separation technologies to remove oocysts and other pathogens, as well as whether the application of separated liquid slurry to agricultural land may represent higher risks for groundwater contamination compared to application of raw slurry. PMID:22706058

A fast and sensitive method for the separation of carotenoids using ultra-high performance supercritical fluid chromatography-mass spectrometry.

PubMed

Jumaah, Firas; Plaza, Merichel; Abrahamsson, Victor; Turner, Charlotta; Sandahl, Margareta

2016-08-01

In this study, a rapid and sensitive ultra-high performance supercritical fluid chromatography-mass spectrometry (UHPSFC-MS) method has been developed and partially validated for the separation of carotenoids within less than 6 min. Six columns of orthogonal selectivity were examined, and the best separation was obtained by using a 1-aminoanthracene (1-AA) column. The length of polyene chain as well as the number of hydroxyl groups in the structure of the studied carotenoids determines their differences in the physiochemical properties and thus the separation that is achieved on this column. All of the investigated carotenoids were baseline separated with resolution values greater than 1.5. The effects of gradient program, back pressure, and column temperature were studied with respect to chromatographic properties such as retention and selectivity. Electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) were compared in both positive and negative mode, using both direct infusion and hyphenated with UHPSFC. The ESI in positive mode provided the highest response. The coefficient of determination (R (2)) for all calibration curves were greater than 0.998. Limit of detection (LOD) was in the range of 2.6 and 25.2 ng/mL for α-carotene and astaxanthin, respectively, whereas limit of quantification (LOQ) was in the range of 7.8 and 58.0 ng/mL for α-carotene and astaxanthin, respectively. Repeatability and intermediate precision of the developed UHPSFC-MS method were determined and found to be RSD < 3 % and RSD < 6 %, respectively. The method was applied in order to determine carotenoids in supercritical fluid extracts of microalgae and rosehip. Graphical Abstract Ultra-high performance supercritical fluid chromatography-a rapid separation method for the analysis of carotenoids in rosehip and microalgae samples.

A silica monolithic column prepared by the sol-gel process for enantiomeric separation by capillary electrochromatography.

PubMed

Kang, Jingwu; Wistuba, Dorothee; Schurig, Volker

2002-04-01

A method for the preparation of a silica monolithic capillary electrochromatography (CEC) column for the separation of enantiomers has been developed. The porous silica monolith was fabricated inside a fused-silica capillary column by using the sol-gel process. After gelation for 24 h, hydrothermal treatment at 100 degrees C for 24 h was performed to prevent the sol-gel matrix from cracking. The prepared monolith was then coated with Chirasil-beta-Dex which represents a chiral polymer prepared by grafting permethyl-beta-cyclodextrin to polymethylsiloxane with an octamethylene spacer. Immobilization of Chirasil-beta-Dex was performed by heat treatment at 120 degrees C for 48 h to give a nonextractable coating. The column performance was evaluated by using racemic hexobarbital as a model compound. The efficiency of 9.2 x 10(4) theoretical plates/m for the first eluted enantiomer of hexobarbital was obtained at an optimal flow rate of the mobile phase. The effect of mobile phase composition on enantiomeric separation of hexobarbital was also investigated. The column proved to be stable for more than one hundreds of runs during a two-months period. The enantiomers of several neutral and negatively charged chiral compounds were baseline separated on this column.

Development of an analytical method for separation of phenolic acids by ultra-performance convergence chromatography (UPC2) using a column packed with a sub-2-μm particle.

PubMed

Jiang, Hai; Yang, Liu; Xing, Xudong; Yan, Meiling; Guo, Xinyue; Yang, Bingyou; Wang, Qiu-Hong; Kuang, Hai-Xue

2018-05-10

Phenolic acids are important active components of certain Traditional Chinese Medicines (TCM) and have a wide range of biological effects. Separation and purification of phenolic acids remains challenging due to difficulties with quality control using existing chromatographic methods The purpose of this study was to compare the effects of different chromatographic columns and conditions for the separation of phenolic acids. The BEH column was determined to be optimal, providing efficient separation in the shortest time (17.00 min) using gradient elution with carbon dioxide as the mobile phase, methanol/acetonitrile (70:30, v/v) with 1% TFA as the modifier, and a flow rate of 0.8 mL/min. Good peak shapes were obtained, and the peak asymmetry values were close to 1.00 for all phenolic acids. The resolution was more than 2.83 for all separated peaks. The developed method was subsequently applied to the determination of phenolic acids in Xanthii Fructus. These results are beneficial for quality control and standardization of herbal drugs using UPC 2 , providing an efficient, rapid and environmentally friendly scientific basis for future analysis of phenolic acids. Copyright © 2018. Published by Elsevier B.V.

Sub-1min separation in sequential injection chromatography for determination of synthetic water-soluble dyes in pharmaceutical formulation.

PubMed

Davletbaeva, Polina; Chocholouš, Petr; Bulatov, Andrey; Šatínský, Dalibor; Solich, Petr

2017-09-05

Sequential Injection Chromatography (SIC) evolved from fast and automated non-separation Sequential Injection Analysis (SIA) into chromatographic separation method for multi-element analysis. However, the speed of the measurement (sample throughput) is due to chromatography significantly reduced. In this paper, a sub-1min separation using medium polar cyano monolithic column (5mm×4.6mm) resulted in fast and green separation with sample throughput comparable with non-separation flow methods The separation of three synthetic water-soluble dyes (sunset yellow FCF, carmoisine and green S) was in a gradient elution mode (0.02% ammonium acetate, pH 6.7 - water) with flow rate of 3.0mLmin -1 corresponding with sample throughput of 30h -1 . Spectrophotometric detection wavelengths were set to 480, 516 and 630nm and 10Hz data collection rate. The performance of the separation was described and discussed (peak capacities 3.48-7.67, peak symmetries 1.72-1.84 and resolutions 1.42-1.88). The method was represented by validation parameters: LODs of 0.15-0.35mgL -1 , LOQs of 0.50-1.25mgL -1 , calibration ranges 0.50-150.00mgL -1 (r>0.998) and repeatability at 10.0mgL -1 of RSD≤0.98% (n=6). The method was used for determination of the dyes in "forest berries" colored pharmaceutical cough-cold formulation. The sample matrix - pharmaceuticals and excipients were not interfering with vis determination because of no retention in the separation column and colorless nature. The results proved the concept of fast and green chromatography approach using very short medium polar monolithic column in SIC. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of citrus limonoid glucosides by high performance liquid chromatography coupled to post-column reaction with Ehrlich’s Reagent

USDA-ARS?s Scientific Manuscript database

A method for the identification and quantification of citrus limonoid glucosides in juices based upon high performance liquid chromatography (HPLC) separation coupled to post-column reaction with Ehrlichs’s reagent has been developed. This method utilizes a phenyl stationary phase and an isocratic ...

Systematic Interpolation Method Predicts Antibody Monomer-Dimer Separation by Gradient Elution Chromatography at High Protein Loads.

PubMed

Creasy, Arch; Reck, Jason; Pabst, Timothy; Hunter, Alan; Barker, Gregory; Carta, Giorgio

2018-05-29

A previously developed empirical interpolation (EI) method is extended to predict highly overloaded multicomponent elution behavior on a cation exchange (CEX) column based on batch isotherm data. Instead of a fully mechanistic model, the EI method employs an empirically modified multicomponent Langmuir equation to correlate two-component adsorption isotherm data at different salt concentrations. Piecewise cubic interpolating polynomials are then used to predict competitive binding at intermediate salt concentrations. The approach is tested for the separation of monoclonal antibody monomer and dimer mixtures by gradient elution on the cation exchange resin Nuvia HR-S. Adsorption isotherms are obtained over a range of salt concentrations with varying monomer and dimer concentrations. Coupled with a lumped kinetic model, the interpolated isotherms predict the column behavior for highly overloaded conditions. Predictions based on the EI method showed good agreement with experimental elution curves for protein loads up to 40 mg/mL column or about 50% of the column binding capacity. The approach can be extended to other chromatographic modalities and to more than two components. This article is protected by copyright. All rights reserved.

Recovery of 131I from alkaline solution of n-irradiated tellurium target using a tiny Dowex-1 column.

PubMed

Chattopadhyay, Sankha; Saha Das, Sujata

2010-10-01

A simple and inexpensive ion-exchange chromatography method for the separation of medically useful no-carrier-added (nca) iodine radionuclides from bulk amounts of irradiated tellurium dioxide (TeO(2)) target was developed and tested using (131)I. The radiochemical separation was performed using a very small Dowex-1x8 ion-exchange column. The overall radiochemical yield for the complete separation of (131)I was 92+/-1.8 (standard deviation) % (n=8). The separated nca (131)I was of high, approximately 99%, radionuclidic and radiochemical purity and did not contain detectable amounts of the target material. This method may be adopted for the radiochemical separation of other different iodine radionuclides produced from tellurium matrices through cyclotron as well as reactor irradiation. Copyright 2010 Elsevier Ltd. All rights reserved.

Highly Sensitive Determination of 2,4,6-Trinitrotoluene and Related Byproducts Using a Diol Functionalized Column for High Performance Liquid Chromatography

PubMed Central

Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O.; Tekinay, Turgay

2014-01-01

In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95–98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation. PMID:24905826

Highly sensitive determination of 2,4,6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography.

PubMed

Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O; Tekinay, Turgay

2014-01-01

In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation.

Validated HPLC method for determination of sennosides A and B in senna tablets.

PubMed

Sun, Shao Wen; Su, Hsiu Ting

2002-07-31

This study developed an efficient and reliable ion-pair liquid chromatographic method for quantitation of sennosides A and B in commercial senna tablets. Separation was conducted on a Hypersil C 18 column (250 x 4.6 mm, 5 microm) at a temperature of 40 degrees C, using a mixture of 0.1 M acetate buffer (pH 6.0) and acetonitrile (70:30, v/v) containing 5 mM tetrahexylammonium bromide as mobile phase. Sennosides A and B were completely separated from other constituents within 14 min. The developed method was validated. Both run-to-run repeatability (n=10) and day-to-day reproducibility (n=3) of peak area were below 0.4% RSD. Linearity of peak area was tested in the range 30-70 microg/ml (r>0.9997). Accuracy was assessed with recovery and the recoveries for sennosides A and B were 101.73+/-1.30% and 101.81+/-2.18% (n=3 x 6), respectively. Robustness of the analytical method was tested using a three-leveled Plackett-Burman design in which 11 factors were assessed with 23 experiments. Eight factors (column, concentration of ion pair reagent, % of organic modifier (acetonitrile), buffer pH, column temperature, flow rate, time constant and detection wavelength) were investigated in a specified range above and below the nominal method conditions. It was found that: (1) column and % acetonitrile affected significantly resolution and retention time, (2) column, % acetonitrile, column temperature, flow rate and time constant affected significantly the plate number of sennoside A, and (3) column and time constant affected significantly the tailing factor.

A rapid method for the sequential separation of polonium, plutonium, americium and uranium in drinking water.

PubMed

Lemons, B; Khaing, H; Ward, A; Thakur, P

2018-06-01

A new sequential separation method for the determination of polonium and actinides (Pu, Am and U) in drinking water samples has been developed that can be used for emergency response or routine water analyses. For the first time, the application of TEVA chromatography column in the sequential separation of polonium and plutonium has been studied. This method utilizes a rapid Fe +3 co-precipitation step to remove matrix interferences, followed by plutonium oxidation state adjustment to Pu 4+ and an incubation period of ~ 1 h at 50-60 °C to allow Po 2+ to oxidize to Po 4+ . The polonium and plutonium were then separated on a TEVA column, while separation of americium from uranium was performed on a TRU column. After separation, polonium was micro-precipitated with copper sulfide (CuS), while actinides were micro co-precipitated using neodymium fluoride (NdF 3 ) for counting by the alpha spectrometry. The method is simple, robust and can be performed quickly with excellent removal of interferences, high chemical recovery and very good alpha peak resolution. The efficiency and reliability of the procedures were tested by using spiked samples. The effect of several transition metals (Cu 2+ , Pb 2+ , Fe 3+ , Fe 2+ , and Ni 2+ ) on the performance of this method were also assessed to evaluate the potential matrix effects. Studies indicate that presence of up to 25 mg of these cations in the samples had no adverse effect on the recovery or the resolution of polonium alpha peaks. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Simultaneous determination of vitamins A, D3 and E in infant formula and adult nutritions by online two-dimensional liquid chromatography].

PubMed

Zhang, Yanhai; Qibule, Hasi; Jin, Yan; Wang, Jia; Ma, Wenli

2015-03-01

A rapid method for the simultaneous determination of vitamins A, D3 and E in infant formula and adult nutritions has been developed using online two-dimensional liquid chromatography (2D-LC). First of all, C8 and polar embedded C18 columns were chosen as the first and second dimensional column respectively according to hydrophobic-subtraction model, which constituted excellent orthogonal separation system. The detection wavelengths were set at 263 nm for vitamin D3, 296 nm for vitamin E and 325 nm for vitamin A. The purification of vitamin D3 and quantifications of vitamins A and E were completed simultaneously in the first dimensional separation using the left pump of Dual Gradient LC (DGLC) with methanol, acetonitrile and water as mobile phases. The heart-cutting time window of vitamin D3 was confirmed according to the retention time of vitamin D3 in the first dimensional separation. The elute from the first dimensional column (1-D column) which contained vitamin D3 was collected by a 500 µL sample loop and then taken into the second dimensional column (2-D column) by the right pump of DGLC with methanol, acetonitrile and water as mobile phases. The quantification of vitamin D3 was performed in the second dimensional separation with vitamin D2 as internal standard. At last, this method was applied for the analysis of the three vitamins in milk powder, cheese and yogurt. The injected sample solution with no further purification was pre-treated by hot-saponification using 1. 25 kg/L KOH solution and extracted by petroleum ether solvent. The recoveries of vitamin D3 spiked in all samples were 75.50%-85.00%. There was no statistically significant difference for the results between this method and standard method through t-test. The results indicate that vitamins A, D3 and E in infant formula and adult fortified dairy can be determined rapidly and accurately with this method.

Assessment of removal efficiency of perfluorocompounds (PFCs) in a semiconductor fabrication plant by gas chromatography.

PubMed

Ou Yang, Chang-Feng; Kam, Seak-Hong; Liu, Chia-Hung; Tzou, Jiren; Wang, Jia-Lin

2009-08-01

This study investigated a gas chromatographic (GC) method to assess the destruction or removal efficiency (DRE) of local scrubbers on five perfluorocompounds (PFCs), i.e., SF(6), NF(3), CF(4), C(2)F(6), and C(3)F(8), which are very potent greenhouse gases used in a semiconductor fabrication plant. Air samples taken at inlets and outlets of local scrubbers were analyzed by a self-constructed multi-column GC system equipped with thermal conductivity detection. Three packed columns were integrated into the heart-cut GC system to allow simultaneous analysis of the five target PFCs. The Porapak Q pre-column performs rough separation and cuts eluent groups to two analytical columns for optimal separation. The Molecular Sieve - 5A column separated NF(3), CF(4), and C(3)F(8) and the second Porapak Q separated SF(6) and C(2)F(6). Linearity was greater than 0.995 (R(2)) for the five PFCs, and the reproducibility was about 4% (relative standard deviation) for NF(3), and better than 0.5% for the other four PFCs. DRE for the combustion (CB) and electric-thermal types of local scrubbers was evaluated by taking into account the in-line dilution from air and fuel gases. Both flow and tracer methods were employed to deduce the dilution factors (DFs). For the tracer method, helium was employed as the tracer and injected upstream of the scrubbers and thus mixed with the exhaust gas. With this method, the DFs were determined to be in the range from 4.8 to 5.9 for the CB unit, significantly higher than the value of 3.3 based on the flow method. The DREs for the CB unit for C(3)F(8) were greater than 90% and between 40% and 50% for CF(4).

A high-throughput, simultaneous analysis of carotenoids, chlorophylls and tocopherol using sub two micron core shell technology columns.

PubMed

Chebrolu, Kranthi K; Yousef, Gad G; Park, Ryan; Tanimura, Yoshinori; Brown, Allan F

2015-09-15

A high-throughput, robust and reliable method for simultaneous analysis of five carotenoids, four chlorophylls and one tocopherol was developed for rapid screening large sample populations to facilitate molecular biology and plant breeding. Separation was achieved for 10 known analytes and four unknown carotenoids in a significantly reduced run time of 10min. Identity of the 10 analytes was confirmed by their UV-Vis absorption spectras. Quantification of tocopherol, carotenoids and chlorophylls was performed at 290nm, 460nm and 650nm respectively. In this report, two sub two micron particle core-shell columns, Kinetex from Phenomenex (1.7μm particle size, 12% carbon load) and Cortecs from Waters (1.6μm particle size, 6.6% carbon load) were investigated and their separation efficiencies were evaluated. The peak resolutions were >1.5 for all analytes except for chlorophyll-a' with Cortecs column. The ruggedness of this method was evaluated in two identical but separate instruments that produced CV<2 in peak retentions for nine out of 10 analytes separated. Copyright © 2015 Elsevier B.V. All rights reserved.

Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

2014-01-10

Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time. Copyright © 2013 Elsevier B.V. All rights reserved.

Gradient stationary phase optimized selectivity liquid chromatography with conventional columns.

PubMed

Chen, Kai; Lynen, Frédéric; Szucs, Roman; Hanna-Brown, Melissa; Sandra, Pat

2013-05-21

Stationary phase optimized selectivity liquid chromatography (SOSLC) is a promising technique to optimize the selectivity of a given separation. By combination of different stationary phases, SOSLC offers excellent possibilities for method development under both isocratic and gradient conditions. The so far available commercial SOSLC protocol utilizes dedicated column cartridges and corresponding cartridge holders to build up the combined column of different stationary phases. The present work is aimed at developing and extending the gradient SOSLC approach towards coupling conventional columns. Generic tubing was used to connect short commercially available LC columns. Fast and base-line separation of a mixture of 12 compounds containing phenones, benzoic acids and hydroxybenzoates under both isocratic and linear gradient conditions was selected to demonstrate the potential of SOSLC. The influence of the connecting tubing on the deviation of predictions is also discussed.

Particle detector spatial resolution

DOEpatents

Perez-Mendez, V.

1992-12-15

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution is disclosed. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector. 12 figs.

Particle detector spatial resolution

DOEpatents

Perez-Mendez, Victor

1992-01-01

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector.

On-line SPE-UHPLC method using fused core columns for extraction and separation of nine illegal dyes in chilli-containing spices.

PubMed

Khalikova, Maria A; Satínský, Dalibor; Smidrkalová, Tereza; Solich, Petr

2014-12-01

The presented work describes the development of a simple, fast and effective on-line SPE-UHPLC-UV/vis method using fused core particle columns for extraction, separation and quantitative analysis of the nine illegal dyes, most frequently found in chilli-containing spices. The red dyes Sudan I-IV, Sudan Red 7B, Sudan Red G, Sudan Orange G, Para Red, and Methyl Red were separated and analyzed in less than 9 min without labor-consuming pretreatment procedure. The chromatographic separation was performed on Ascentis Express RP-Amide column with gradient elution using mixture of acetonitrile and water, as a mobile phase at a flow rate of 1.0 mL min(-1) and 55°C of temperature. As SPE sorbent for cleanup and pre-concentration of illegal dyes short guard fused core column Ascentis Express F5 was used. The applicability of proposed method was proven for three different chilli-containing commercial samples. Recoveries for all compounds were between 90% and 108% and relative standard deviation ranged from 1% to 4% for within- and from 2% to 6% for between-day. Limits of detection showed lower values than required by European Union regulations and were in the range of 3.3-10.3 µg L(-1) for standard solutions, 5.6-235.6 µg kg(-1) for chilli-containing spices. Copyright © 2014 Elsevier B.V. All rights reserved.

A simple and rapid technique for radiochemical separation of iodine radionuclides from irradiated tellurium using an activated charcoal column.

PubMed

Chattopadhyay, Sankha; Saha Das, Sujata

2009-10-01

A simple and inexpensive method for the separation of medically useful no-carrier-added (nca) iodine radionuclides from bulk amounts of irradiated tellurium dioxide (TeO(2)) target was developed. The beta(-) emitting (131)I radionuclide, produced by the decay of (131)Te through the (nat)Te(n, gamma)(131)Te nuclear reaction, was used for standardization of the radiochemical separation procedure. The radiochemical separation was performed by precipitation followed by column (activated charcoal) chromatography. Quantitative post-irradiation recovery of the TeO(2) target material (98-99%), in a form suitable for reuse in future irradiations, was achieved. The overall radiochemical yield for the complete separation of (131)I was 75-85% (n=8). The separated nca (131)I was of high, approximately 99%, radionuclidic and radiochemical purities and did not contain detectable amounts of the target material. This method can be adopted for the radiochemical separation of other different iodine radionuclides produced from tellurium matrices through cyclotron as well as reactor irradiation.

Rapid quantification of underivatized amino acids in plasma by hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass-spectrometry.

PubMed

Prinsen, Hubertus C M T; Schiebergen-Bronkhorst, B G M; Roeleveld, M W; Jans, J J M; de Sain-van der Velden, M G M; Visser, G; van Hasselt, P M; Verhoeven-Duif, N M

2016-09-01

Amino acidopathies are a class of inborn errors of metabolism (IEM) that can be diagnosed by analysis of amino acids (AA) in plasma. Current strategies for AA analysis include cation exchange HPLC with post-column ninhydrin derivatization, GC-MS, and LC-MS/MS-related methods. Major drawbacks of the current methods are time-consuming procedures, derivative problems, problems with retention, and MS-sensitivity. The use of hydrophilic interaction liquid chromatography (HILIC) columns is an ideal separation mode for hydrophilic compounds like AA. Here we report a HILIC-method for analysis of 36 underivatized AA in plasma to detect defects in AA metabolism that overcomes the major drawbacks of other methods. A rapid, sensitive, and specific method was developed for the analysis of AA in plasma without derivatization using HILIC coupled with tandem mass-spectrometry (Xevo TQ, Waters). Excellent separation of 36 AA (24 quantitative/12 qualitative) in plasma was achieved on an Acquity BEH Amide column (2.1×100 mm, 1.7 μm) in a single MS run of 18 min. Plasma of patients with a known IEM in AA metabolism was analyzed and all patients were correctly identified. The reported method analyzes 36 AA in plasma within 18 min and provides baseline separation of isomeric AA such as leucine and isoleucine. No separation was obtained for isoleucine and allo-isoleucine. The method is applicable to study defects in AA metabolism in plasma.

Improved quality-by-design compliant methodology for method development in reversed-phase liquid chromatography.

PubMed

Debrus, Benjamin; Guillarme, Davy; Rudaz, Serge

2013-10-01

A complete strategy dedicated to quality-by-design (QbD) compliant method development using design of experiments (DOE), multiple linear regressions responses modelling and Monte Carlo simulations for error propagation was evaluated for liquid chromatography (LC). The proposed approach includes four main steps: (i) the initial screening of column chemistry, mobile phase pH and organic modifier, (ii) the selectivity optimization through changes in gradient time and mobile phase temperature, (iii) the adaptation of column geometry to reach sufficient resolution, and (iv) the robust resolution optimization and identification of the method design space. This procedure was employed to obtain a complex chromatographic separation of 15 antipsychotic basic drugs, widely prescribed. To fully automate and expedite the QbD method development procedure, short columns packed with sub-2 μm particles were employed, together with a UHPLC system possessing columns and solvents selection valves. Through this example, the possibilities of the proposed QbD method development workflow were exposed and the different steps of the automated strategy were critically discussed. A baseline separation of the mixture of antipsychotic drugs was achieved with an analysis time of less than 15 min and the robustness of the method was demonstrated simultaneously with the method development phase. Copyright © 2013 Elsevier B.V. All rights reserved.

Low energy consumption method for separating gaseous mixtures and in particular for medium purity oxygen production

DOEpatents

Jujasz, Albert J.; Burkhart, James A.; Greenberg, Ralph

1988-01-01

A method for the separation of gaseous mixtures such as air and for producing medium purity oxygen, comprising compressing the gaseous mixture in a first compressor to about 3.9-4.1 atmospheres pressure, passing said compressed gaseous mixture in heat exchange relationship with sub-ambient temperature gaseous nitrogen, dividing the cooled, pressurized gaseous mixture into first and second streams, introducing the first stream into the high pressure chamber of a double rectification column, separating the gaseous mixture in the rectification column into a liquid oxygen-enriched stream and a gaseous nitrogen stream and supplying the gaseous nitrogen stream for cooling the compressed gaseous mixture, removing the liquid oxygen-enriched stream from the low pressure chamber of the rectification column and pumping the liquid, oxygen-enriched steam to a predetermined pressure, cooling the second stream, condensing the cooled second stream and evaporating the oxygen-enriched stream in an evaporator-condenser, delivering the condensed second stream to the high pressure chamber of the rectification column, and heating the oxygen-enriched stream and blending the oxygen-enriched stream with a compressed blend-air stream to the desired oxygen concentration.

An alternative procedure for uranium analysis in drinking water using AQUALIX columns: application to varied French bottled waters.

PubMed

Bouvier-Capely, C; Bonthonneau, J P; Dadache, E; Rebière, F

2014-01-01

The general population is chronically exposed to uranium ((234)U, (235)U, and (238)U) and polonium ((210)Po) mainly through day-to-day food and beverage intake. The measurement of these naturally-occurring radionuclides in drinking water is important to assess their health impact. In this work the applicability of calix[6]arene-derivatives columns for uranium analysis in drinking water was investigated. A simple and effective method was proposed on a specific column called AQUALIX, for the separation and preconcentration of U from drinking water. This procedure is suitable for routine analysis and the analysis time is considerably shortened (around 4h) by combining the separation on AQUALIX with fast ICP-MS measurement. This new method was tested on different French bottled waters (still mineral water, sparkling mineral water, and spring water). Then, the case of simultaneous presence of uranium and polonium in water was considered due to interferences in alpha spectrometry measurement. A protocol was proposed using a first usual step of spontaneous deposition of polonium on silver disc in order to separate Po, followed by the uranium extraction on AQUALIX column before alpha spectrometry counting. © 2013 Published by Elsevier B.V.

Cavitating flow during water hammer using a generalized interface vaporous cavitation model

NASA Astrophysics Data System (ADS)

Sadafi, Mohamadhosein; Riasi, Alireza; Nourbakhsh, Seyed Ahmad

2012-10-01

In a transient flow simulation, column separation may occur when the calculated pressure head decreases to the saturated vapor pressure head in a computational grid. Abrupt valve closure or pump failure can result in a fast transient flow with column separation, potentially causing problems such as pipe failure, hydraulic equipment damage, cavitation or corrosion. This paper reports a numerical study of water hammer with column separation in a simple reservoir-pipeline-valve system and pumping station. The governing equations for two-phase transient flow in pipes are solved based on the method of characteristics (MOC) using a generalized interface vaporous cavitating model (GIVCM). The numerical results were compared with the experimental data for validation purposes, and the comparison indicated that the GIVCM describes the experimental results more accurately than the discrete vapor cavity model (DVCM). In particular, the GIVCM correlated better with the experimental data than the DVCM in terms of timing and pressure magnitude. The effects of geometric and hydraulic parameters on flow behavior in a pumping station with column separation were also investigated in this study.

NEW COLUMN SEPARATION METHOD FOR EMERGENCY URINE SAMPLES

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

Maxwell, S; Brian Culligan, B

2007-08-28

The Savannah River Site Environmental Bioassay Lab participated in the 2007 NRIP Emergency Response program administered by the National Institute for Standards and Technology (NIST) in May, 2007. A new rapid column separation method was applied directly to the NRIP 2007 emergency urine samples, with only minimal sample preparation to reduce preparation time. Calcium phosphate precipitation, previously used to pre-concentrate actinides and Sr-90 in NRIP 2006 urine and water samples, was not used for the NRIP 2007 urine samples. Instead, the raw urine was acidified and passed directly through the stacked resin columns (TEVA+TRU+SR Resins) to separate the actinides andmore » strontium from the NRIP urine samples more quickly. This improvement reduced sample preparation time for the NRIP 2007 emergency urine analyses significantly. This approach works well for small volume urine samples expected during an emergency response event. Based on initial feedback from NIST, the SRS Environmental Bioassay Lab had the most rapid analysis times for actinides and strontium-90 analyses for NRIP 2007 urine samples.« less

Separation-oriented derivatization of native fluorescent compounds through fluorous labeling followed by liquid chromatography with fluorous-phase.

PubMed

Sakaguchi, Yohei; Yoshida, Hideyuki; Todoroki, Kenichiro; Nohta, Hitoshi; Yamaguchi, Masatoshi

2009-06-15

We have developed a new and simple method based on "fluorous derivatization" for LC of native fluorescent compounds. This method involves the use of a column with a fluorous stationary phase. Native fluorescent analytes with target functional groups are precolumn derivatized with a nonfluorescent fluorous tag, and the fluorous-labeled analytes are retained in the column, whereas underivatized substances are not. Only the retained fluorescent analytes are detected fluorometrically at appropriate retention times, and retained substrates without fluorophores are not detected. In this study, biologically important carboxylic acids (homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid) and drugs (naproxen, felbinac, flurbiprofen, and etodolac) were used as model native fluorescent compounds. Experimental results indicate that the fluorous-phase column can selectively retain fluorous compounds including fluorous-labeled analytes on the basis of fluorous separation. We believe that separation-oriented derivatization presented here is the first step toward the introduction of fluorous derivatization in quantitative LC analysis.

Radiochemical Applications of Insoluble Sulfate Columns. Analytical Possibilities in the Field of the Fission Product Solutions; APLICACIONES RADIO-QUIMICAS DE LAS COLUMNAS DE PRECIPITADOS DE SULFATOS INSOLUBLES. CONTRIBUCION AL ESTUDIO DE LAS SOLUCIONES ENVEJECIDAS DE PRODUCTOS DE FISION

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

Barrachina, M.; Sauvagnac, R.

1962-01-01

The heterogeneous ion-isotopic exchange column is used to determine the radiochemical composition of raw solutions used in the industrial recuperation of long-lived fission products, The separation of the radioelements is made by small columns, 1--3 cm height, of BaSO/sub 4/ or SrSO/sub 4/, under selected experimental conditions. These columns behave like inorganic exchangers, working by adsorption or ion-isotopic exchange depending on the cases, and they provide selective separation of fission products employing very small volumes of fixing and eluting solutions. By coupling the separative capabilities of these columns and the liquid--liquid extraction with the 2-thenoyltrifluoroacetone and the di-2 ethylexyl orthophosphoricmore » acid, a set of new radiochemical methods, for the determination of Sr/sup 90/, Y/sup 90/, Ce/sup 144/ - Pr/sup 144/, and Pm/sup 147/ in the fission product solutions of Marcoule, were developed. (auth)« less

Blind column selection protocol for two-dimensional high performance liquid chromatography.

PubMed

Burns, Niki K; Andrighetto, Luke M; Conlan, Xavier A; Purcell, Stuart D; Barnett, Neil W; Denning, Jacquie; Francis, Paul S; Stevenson, Paul G

2016-07-01

The selection of two orthogonal columns for two-dimensional high performance liquid chromatography (LC×LC) separation of natural product extracts can be a labour intensive and time consuming process and in many cases is an entirely trial-and-error approach. This paper introduces a blind optimisation method for column selection of a black box of constituent components. A data processing pipeline, created in the open source application OpenMS®, was developed to map the components within the mixture of equal mass across a library of HPLC columns; LC×LC separation space utilisation was compared by measuring the fractional surface coverage, fcoverage. It was found that for a test mixture from an opium poppy (Papaver somniferum) extract, the combination of diphenyl and C18 stationary phases provided a predicted fcoverage of 0.48 and was matched with an actual usage of 0.43. OpenMS®, in conjunction with algorithms designed in house, have allowed for a significantly quicker selection of two orthogonal columns, which have been optimised for a LC×LC separation of crude extractions of plant material. Copyright © 2016 Elsevier B.V. All rights reserved.

Short communication: separation and quantification of caseins and casein macropeptide using ion-exchange chromatography.

PubMed

Holland, B; Rahimi Yazdi, S; Ion Titapiccolo, G; Corredig, M

2010-03-01

The aim of this work was to improve an existing method to separate and quantify the 4 major caseins from milk samples (i.e., containing whey proteins) using ion-exchange chromatography. The separation process was carried out using a mini-preparative cation exchange column (1 or 5mL of column volume), using urea acetate as elution buffer at pH 3.5 with a NaCl gradient. All 4 major caseins were separated, and the purity of each peak was assessed using sodium dodecyl sulfate-PAGE. Purified casein fractions were also added to raw milk to confirm their elution volumes. The quantification was carried out using purified caseins in buffer as well as added directly to fresh skim milk. This method can also be employed to determine the decrease in kappa-casein and the release of the casein-macropeptide during enzymatic hydrolysis using rennet. In this case, the main advantage of using this method is the lack of organic solvents compared with the conventional method for separation of macropeptide (using reversed phase HPLC).

Tunable thick porous silica coating fabricated by multilayer-by-multilayer bonding of silica nanoparticles for open-tubular capillary chromatographic separation.

PubMed

Qu, Qishu; Liu, Yuanyuan; Shi, Wenjun; Yan, Chao; Tang, Xiaoqing

2015-06-19

A simple coating procedure employing a multilayer-by-multilayer process to modify the inner surface of bare fused-silica capillaries with silica nanoparticles was established. The silica nanoparticles were adsorbed onto the capillary wall via a strong electrostatic interaction between amino functional groups and silica particles. The thickness of the coating could be tuned from 130 to 600 nm by increasing the coating cycles from one to three. Both the retention factor and the resolution were greatly increased with increasing coating cycles. The loading capacity determined by naphthalene in the column with three coating cycles is 152.1 pmol. The effects of buffer concentration and pH value on the stability of the coating were evaluated. The retention reproducibility of the separation of toluene was 0.8, 1.2, 2.3, and 4.5%, respectively, for run-to-run, day-to-day, column-to-column, and batch-to-batch, respectively. The chromatographic performance of these columns was evaluated by both capillary liquid chromatography and open-tubular capillary electrochromatography (OT-CEC). Separation of aromatic hydrocarbons in the column with three coating cycles provided high theoretical plate numbers (up to 269,280 plates m(-1) for toluene) and short separation time (<15 min) by using OT-CEC mode. The method was also used to separate egg white proteins. Both acidic and basic proteins as well as four glycoisoforms were separated in a single run. Copyright © 2015 Elsevier B.V. All rights reserved.

Assay of free and glycine- and taurine-conjugated bile acids in serum by high-pressure liquid chromatography by using post-column reaction after group separation.

PubMed Central

Onishi, S; Itoh, S; Ishida, Y

1982-01-01

An accurate and sensitive method that involves the group separations of serum bile acids (i.e. free and glycine- and taurine-conjugated bile acid fractions) by ion-exchange chromatography on piperidinohydroxypropyl-Sephadex LH-20 is described. Each group was then analysed by high-pressure liquid chromatography by using the post-column reaction technique with immobilized 3 alpha-hydroxy steroid dehydrogenase. The bile acid patterns in the umbilical venous serum samples were analysed by this method. Taurochenodeoxycholate predominated in the umbilical blood. PMID:6956336

High-performance cation-exchange chromatofocusing of proteins.

PubMed

Kang, Xuezhen; Frey, Douglas D

2003-03-28

Chromatofocusing using high-performance cation-exchange column packings, as opposed to the more commonly used anion-exchange column packings, is investigated with regard to the performance achieved and the range of applications possible. Linear or convex gradients in the range from pH 2.6 to 9 were formed using a variety of commercially available column packings that provide a buffering capacity in different pH ranges, and either polyampholytes or simple mixtures having a small number (three or fewer) of buffering species as the elution buffer. The resolutions achieved using cation-exchange or anion-exchange chromatofocusing were in general comparable, although for certain pairs of proteins better resolution could be achieved using one type of packing as compared to the other, evidently due to the way electrostatic charges are distributed on the protein surface. Several chromatofocusing methods were investigated that take advantage of the acid-base properties of commercially available cation-exchange column packings. These include the use of gradients with a composite shape, the use of very low pH ranges, and the use of elution buffers containing a single buffering species. The advantages of chromatofocusing over ion-exchange chromatography using a salt gradient at constant pH were illustrated by employing the former method and a cation-exchange column packing to separate beta-lactoglobulins A and B, which is a separation reported to be impossible using the latter method and a cation-exchange column packing. Trends in the apparent isoelectric points determined using cation- and anion-exchange chromatofocusing were interpreted using applicable theories. Results of this study indicate that cation-exchange chromatofocusing is a useful technique which is complementary to anion-exchange chromatofocusing and isoelectric focusing for separating proteins at both the analytical and preparative scales.

An on-line SPE-HPLC method for effective sample preconcentration and determination of fenoxycarb and cis, trans-permethrin in surface waters.

PubMed

Šatínský, Dalibor; Naibrtová, Linda; Fernández-Ramos, Carolina; Solich, Petr

2015-09-01

A new on-line SPE-HPLC method using fused-core columns for on-line solid phase extraction and large volume sample injection for increasing the sensitivity of detection was developed for the determination of insecticides fenoxycarb and cis-, trans-permethrin in surface waters. The separation was carried out on fused-core column Phenyl-Hexyl (100×4.6 mm), particle size 2.7 µm with mobile phase acetonitrile:water in gradient mode at flow rate 1.0 mL min(-1), column temperature 45°C. Large volume sample injection (1500 µL) to the extraction dimension using short precolumn Ascentis Express RP C-18 (5×4.6 mm); fused-core particle size 2.7 µm allowed effective sample preconcentration and efficient ballast sample matrix removal. The washing mobile phase consisting of a mixture of acetonitrile:water; 30:70, (v/v) was pumped at flow rate of 0.5 mL min(-1) through the extraction precolumn to the waste. Time of the valve switch for transferring the preconcentrated sample zone from the extraction to the separation column was set at 3rd min. Elution of preconcentrated insecticides from the extraction precolumn and separation on the analytical column was performed in gradient mode. Linear gradient elution started from 40% of acetonitrile at time of valve switch from SPE column (3rd min) to 95% of acetonitrile at 7th min. Synthetic dye sudan I was chosen as an internal standard. UV detection at wavelength 225 nm was used and the method reached the limits of detection (LOD) at ng mL(-1) levels for both insecticides. The method showing on-line sample pretreatment and preconcentration with highly sensitive determination of insecticides was applied for monitoring of fenoxycarb and both permethrin isomers in different surface water samples in Czech Republic. The time of whole analysis including on-line extraction, interferences removal, chromatography separation and system equilibration was less than 8 min. Copyright © 2015 Elsevier B.V. All rights reserved.

Separation of copper, iron, and zinc from complex aqueous solutions for isotopic measurement

USGS Publications Warehouse

Borrok, D.M.; Wanty, R.B.; Ridley, W.I.; Wolf, R.; Lamothe, P.J.; Adams, M.

2007-01-01

The measurement of Cu, Fe, and Zn isotopes in natural samples may provide valuable information about biogeochemical processes in the environment. However, the widespread application of stable Cu, Fe, and Zn isotope chemistry to natural water systems remains limited by our ability to efficiently separate these trace elements from the greater concentrations of matrix elements. In this study, we present a new method for the isolation of Cu, Fe, and Zn from complex aqueous solutions using a single anion-exchange column with hydrochloric acid media. Using this method we are able to quantitatively separate Cu, Fe, and Zn from each other and from matrix elements in a single column elution. Elution of the elements of interest, as well as all other elements, through the anion-exchange column is a function of the speciation of each element in the various concentrations of HCl. We highlight the column chemistry by comparing our observations with published studies that have investigated the speciation of Cu, Fe, and Zn in chloride solutions. The functionality of the column procedure was tested by measuring Cu, Fe, and Zn isotopes in a variety of stream water samples impacted by acid mine drainage. The accuracy and precision of Zn isotopic measurements was tested by doping Zn-free stream water with the Zn isotopic standard. The reproducibility of the entire column separation process and the overall precision of the isotopic measurements were also evaluated. The isotopic results demonstrate that the Cu, Fe, and Zn column separates from the tested stream waters are of sufficient purity to be analyzed directly using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), and that the measurements are fully-reproducible, accurate, and precise. Although limited in scope, these isotopic measurements reveal significant variations in ??65Cu (- 1.41 to + 0.30???), ??56Fe (- 0.56 to + 0.34???), and ??66Zn (0.31 to 0.49???) among samples collected from different abandoned mines within a single watershed. Hence, Cu, Fe, and Zn isotopic measurements may be a powerful tool for fingerprinting specific metal sources and/or examining biogeochemical reactions within fresh water systems.

Sugar, acid and furfural quantification in a sulphite pulp mill: Feedstock, product and hydrolysate analysis by HPLC/RID.

PubMed

Llano, Tamara; Quijorna, Natalia; Andrés, Ana; Coz, Alberto

2017-09-01

Waste from pulp and paper mills consist of sugar-rich fractions comprising hemicellulose derivatives and cellulose by-products. A complete characterisation of the waste streams is necessary to study the possibilities of an existing mill. In this work, four chromatographic methods have been developed to obtain the most suitable chromatographic method conditions for measuring woody feedstocks, lignocellulosic hydrolysates and cellulose pulp in sulphite pulping processes. The analysis of major and minor monosaccharides, aliphatic carboxylic acids and furfurals has been optimised. An important drawback of the spent liquors generated after sulphite pulping is their acidic nature, high viscosity and adhesive properties that interfere in the column lifetime. This work recommends both a CHO-782Pb column for the sugar analysis and an SH-1011 resin-based cross-linked gel column to separate low-molecular-weight chain acids, alcohols and furfurals. Such columns resulted in a good separation with long lifetime, wide pH operating range and low fouling issues.

Fiber-based monolithic columns for liquid chromatography.

PubMed

Ladisch, Michael; Zhang, Leyu

2016-10-01

Fiber-based monoliths for use in liquid chromatographic separations are defined by columns packed with aligned fibers, woven matrices, or contiguous fiber structures capable of achieving rapid separations of proteins, macromolecules, and low molecular weight components. A common denominator and motivating driver for this approach, first initiated 25 years ago, was reducing the cost of bioseparations in a manner that also reduced residence time of retained components while achieving a high ratio of mass to momentum transfer. This type of medium, when packed into a liquid chromatography column, minimized the fraction of stagnant liquid and resulted in a constant plate height for non-adsorbing species. The uncoupling of dispersion from eluent flow rate enabled the surface chemistry of the stationary phase to be considered separately from fluid transport phenomena and pointed to new ways to apply chemistry for the engineering of rapid bioseparations. This paper addresses developments and current research on fiber-based monoliths and explains how the various forms of this type of chromatographic stationary phase have potential to provide new tools for analytical and preparative scale separations. The different stationary phases are discussed, and a model that captures the observed constant plate height as a function of mobile phase velocity is reviewed. Methods that enable hydrodynamically stable fiber columns to be packed and operated over a range of mobile phase flow rates, together with the development of new fiber chemistries, are shown to provide columns that extend the versatility of liquid chromatography using monoliths, particularly at the preparative scale. Graphical Abstract Schematic representation of a sample mixture being separated by a rolled-stationary phase column, resulting separated peaks shown in the chromatogram.

Column-coupling strategies for multidimensional electrophoretic separation techniques.

PubMed

Kler, Pablo A; Sydes, Daniel; Huhn, Carolin

2015-01-01

Multidimensional electrophoretic separations represent one of the most common strategies for dealing with the analysis of complex samples. In recent years we have been witnessing the explosive growth of separation techniques for the analysis of complex samples in applications ranging from life sciences to industry. In this sense, electrophoretic separations offer several strategic advantages such as excellent separation efficiency, different methods with a broad range of separation mechanisms, and low liquid consumption generating less waste effluents and lower costs per analysis, among others. Despite their impressive separation efficiency, multidimensional electrophoretic separations present some drawbacks that have delayed their extensive use: the volumes of the columns, and consequently of the injected sample, are significantly smaller compared to other analytical techniques, thus the coupling interfaces between two separations components must be very efficient in terms of providing geometrical precision with low dead volume. Likewise, very sensitive detection systems are required. Additionally, in electrophoretic separation techniques, the surface properties of the columns play a fundamental role for electroosmosis as well as the unwanted adsorption of proteins or other complex biomolecules. In this sense the requirements for an efficient coupling for electrophoretic separation techniques involve several aspects related to microfluidics and physicochemical interactions of the electrolyte solutions and the solid capillary walls. It is interesting to see how these multidimensional electrophoretic separation techniques have been used jointly with different detection techniques, for intermediate detection as well as for final identification and quantification, particularly important in the case of mass spectrometry. In this work we present a critical review about the different strategies for coupling two or more electrophoretic separation techniques and the different intermediate and final detection methods implemented for such separations.

Separation of natural product using columns packed with Fused-Core particles.

PubMed

Yang, Peilin; Litwinski, George R; Pursch, Matthias; McCabe, Terry; Kuppannan, Krishna

2009-06-01

Three HPLC columns packed with 3 microm, sub-2 microm, and 2.7 microm Fused-Core (superficially porous) particles were compared in separation performance using two natural product mixtures containing 15 structurally related components. The Ascentis Express C18 column packed with Fused-Core particles showed an 18% increase in column efficiency (theoretical plates), a 76% increase in plate number per meter, a 65% enhancement in separation speed and a 19% increase in back pressure compared to the Atlantis T3 C18 column packed with 3 microm particles. Column lot-to-lot variability for critical pairs in the natural product mixture was observed with both columns, with the Atlantis T3 column exhibiting a higher degree of variability. The Ascentis Express column was also compared with the Acquity BEH column packed with sub-2 microm particles. Although the peak efficiencies obtained by the Ascentis Express column were only about 74% of those obtained by the Acquity BEH column, the 50% lower back pressure and comparable separation speed allowed high-efficiency and high-speed separation to be performed using conventional HPLC instrumentation.

Methacrylate-bonded covalent-organic framework monolithic columns for high performance liquid chromatography.

PubMed

Liu, Li-Hua; Yang, Cheng-Xiong; Yan, Xiu-Ping

2017-01-06

Covalent-organic frameworks (COFs) are a newfangled class of intriguing microporous materials. Considering their unique properties, COFs should be promising as packing materials for high performance liquid chromatography (HPLC). However, the irregular shape and sub-micrometer size of COFs synthesized via the traditional methods render the main obstacles for the application of COFs in HPLC. Herein, we report the preparation of methacrylate-bonded COF monolithic columns for HPLC to overcome the above obstacles. The prepared COF bonded monolithic columns not only show good homogeneity and permeability, but also give high column efficiency, good resolution and precision for HPLC separation of small molecules including polycyclic aromatic hydrocarbons, phenols, anilines, nonsteroidal anti-inflammatory drugs and benzothiophenes. Compared with the bare polymer monolithic column, the COF bonded monolithic columns show enhanced hydrophobic, π-π and hydrogen bond interactions in reverse phase HPLC. The results reveal the great potential of COF bonded monoliths for HPLC and COFs in separation sciences. Copyright © 2016 Elsevier B.V. All rights reserved.

High-pressure liquid chromatography with direct injection of gas sample.

PubMed

Astanin, Anton I; Baram, Grigory I

2017-06-09

The conventional method of using liquid chromatography to determine the composition of a gaseous mixture entails dissolving vapors in a suitable solvent, then obtaining a chromatograph of the resulting solution. We studied the direct introduction of a gaseous sample into a C18 reversed-phase column, followed by separation of the components by HPLC with UV detection. Since the chromatography was performed at high pressure, vapors readily dissolved in the eluent and the substances separated in the column as effectively as in liquid samples. Samples were injected into the column in two ways: a) through the valve without a flow stop; b) after stopping the flow and relieving all pressure. We showed that an injectable gas volume could reach 70% of column dead volume. When an injected gaseous sample volume was less than 10% of the column dead volume, the resulting peaks were symmetrical and the column efficiency was high. Copyright © 2017 Elsevier B.V. All rights reserved.

Stereospecific analysis of loxoprofen in plasma by chiral column liquid chromatography with a circular dichroism-based detector.

PubMed

Kanazawa, Hideko; Tsubayashi, Akane; Nagata, Yoshiko; Matsushima, Yoshikazu; Mori, Chiharu; Kizu, Junko; Higaki, Megumu

2002-03-01

The chiral separation of loxoprofen was achieved on a chiral column with UV and circular dichroism (CD) detection. The good resolution of four loxoprofen stereoisomers was obtained. The column used for the chiral separation was Chiralcel OJ column (250 x 4.6 mm) using hexane-2-propanol-trifluoroacetic acid (95:5:0.1), as an eluent. The flow-rate was 1.0 ml/min and the detection was at 225 nm. In addition, CD and UV spectra were obtained by stopped flow scanning. The method allows the determination of the stereoisomers of loxoprofen in human plasma after the administration of therapeutic dose of the racemic drug, thus HPLC with CD detector is useful for the stereospecific determination of loxoprofen products in biological samples.

Separation techniques: Chromatography

PubMed Central

Coskun, Ozlem

2016-01-01

Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis. Proteins can be purified based on characteristics such as size and shape, total charge, hydrophobic groups present on the surface, and binding capacity with the stationary phase. Four separation techniques based on molecular characteristics and interaction type use mechanisms of ion exchange, surface adsorption, partition, and size exclusion. Other chromatography techniques are based on the stationary bed, including column, thin layer, and paper chromatography. Column chromatography is one of the most common methods of protein purification. PMID:28058406

Silver ion chromatography for peak resolution enhancement: Application to the preparative separation of two sesquiterpenes using online heart-cutting LC-LC technique.

PubMed

Yang, Yang; Zhang, Yongmin; Wei, Chong; Li, Jing; Sun, Wenji

2018-09-01

Silver ion chromatography, utilizing columns packed with silver ions bonded to silica gel, has proved to be an invaluable technique for the analysis of some positional isomers. In this work, silver ion chromatography by combination with online heart-cutting LC-LC technique for the preparative separation of two sesquiterpenes positional isomers from a natural product was investigated. On the basis of the evaluation that silver ion content impacts on the separation, the laboratory-made silver ion columns, utilizing silica gel impregnated with 15% silver nitrate as column packing materials, were used for peak resolution improvement of these two isomers and the preparative separation of them in heart-cutting LC-LC. The relationship among the maximal sample load, flow rate and peak resolution in the silver ion column were optimized, and the performance of the silver ion column was compared with conventional C 18 column and silica gel column. Based on the developed chromatographic conditions, online heart-cutting LC-LC chromatographic separation system in combination with a silica gel column and a silver ion column that was applied to preparative separation of these two isomers from a traditional Chinese medicine, Inula racemosa Hook.f., was established. The results showed that the online heart-cutting LC-LC technique by combination of a silica gel column and a silver ion column for the preparative separation of these two positional isomers from this natural plant was superior to the preparative separation performed on a single-column system with C 18 column or silica gel column. Copyright © 2018 Elsevier B.V. All rights reserved.

Two multidimensional chromatographic methods for enantiomeric analysis of o,p'-DDT and o,p'-DDD in contaminated soil and air in a malaria area of South Africa.

PubMed

Naudé, Yvette; Rohwer, Egmont R

2012-06-12

In rural parts of South Africa the organochlorine insecticide DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is still used for malaria vector control where traditional dwellings are sprayed on the inside with small quantities of technical DDT. Since o,p'-DDT may show enantioselective oestrogenicity and biodegradability, it is important to analyse enantiomers of o,p'-DDT and its chiral degradation product, o,p'-DDD, for both health and environmental-forensic considerations. Generally, chiral analysis is performed using heart-cut multidimensional gas chromatography (MDGC) and, more recently, comprehensive two-dimensional gas chromatography (GC×GC). We developed an off-line gas chromatographic fraction collection (heart-cut) procedure for the selective capturing of the appropriate isomers from a first apolar column, followed by reinjection and separation on a second chiral column. Only the o,p'-isomers of DDT and DDD fractions from the first dimension complex chromatogram (achiral apolar GC column separation) were selectively collected onto a polydimethylsiloxane (PDMS) multichannel open tubular silicone rubber trap by simply placing the latter device on the flame tip of an inactivated flame ionisation detector (FID). The multichannel trap containing the o,p'-heart-cuts was then thermally desorbed into a GC with time-of-flight mass spectrometry detection (GC-TOFMS) for second dimension enantioselective separation on a chiral column (β-cyclodextrin-based). By selectively capturing only the o,p'-isomers from the complex sample chromatogram, (1)D separation of ultra-trace level enantiomers could be achieved on the second chiral column without matrix interference. Here, we present solventless concentration techniques for extraction of DDT from contaminated soil and air, and report enantiomeric fraction (EF) values of o,p'-DDT and o,p'-DDD obtained by a new multidimensional approach for heart-cut gas chromatographic fraction collection for off-line second dimension enantiomeric separation by (1)D GC-TOFMS of selected isomers. This multidimensional method is compared to the complementary technique of comprehensive GC×GC-TOFMS using the same enantioselective column, this time as the first dimension of separation. Copyright © 2012 Elsevier B.V. All rights reserved.

Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent.

PubMed

Kifle, Dejene; Wibetoe, Grethe

2013-09-13

One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III. Copyright © 2013 Elsevier B.V. All rights reserved.

Characterization of free thiol variants of an IgG1 by reversed phase ultra high pressure liquid chromatography coupled with mass spectrometry.

PubMed

Liu, Hongbin; Jeong, Justin; Kao, Yung-Hsiang; Zhang, Yonghua Taylor

2015-05-10

RP-HPLC has been demonstrated as a powerful tool to study antibody free thiol and disulfide variants. Recently, the introduction of UHPLC columns with wide pore size (300Å) and small particle size (1.7μm) offered the opportunity to further improve the separation of such variants. This paper describes a systematic evaluation of stationary phases, operating parameters, and mobile phases for a UHPLC based method to separate free thiol variants of a recombinant monoclonal antibody (referred as mAb A), targeting high resolution, high throughput and improved recovery. Among the four different stationary phases evaluated, UHPLC diphenyl columns were found to provide the best separation. Using an optimized UHPLC method, free thiol variants of mAb A were separated in 5min. Importantly, the UHPLC method revealed minor variants that had coeluted in an HPLC based method, and the UHPLC method is also applicable as a platform method for characterization of other mAbs as well. Furthermore, an on-line UHPLC-MS method was developed to characterize the separated variants, and this method can streamline the characterization of fully assembled monoclonal and bispecific therapeutic antibodies. Copyright © 2015 Elsevier B.V. All rights reserved.

[Rapid determination of trace iodate using monolithic column ion-pair chromatography coupled with direct conductivity detection].

PubMed

Liu, Yuzhen; Yu, Hong; Li, Siwen

2011-10-01

A method was developed on a monolithic column for the fast determination of trace iodate (IO(3)- ) by ion-pair chromatography with direct conductivity detection. The analytes were separated using a mobile phase of tetrabutylammonium hydroxide (TBA)-phthalic acid-acetonitrile on a reversed-phase silica-based monolithic column. The effects of eluent, flow rate and column temperature on the retention of iodate were investigated. The optimized chromatographic conditions for the determination of the anion were as follows: 0. 25 mmol/L TBA-0. 18 mmol/L phthalic acid-3% acetonitrile (pH 5.5) as mobile phase, a flow rate of 4.0 mL/min and a column temperature of 30 degrees C. Under the optimal conditions, retention time of iodate was less than 0. 5 min and the baseline separation of iodate was achieved without any interference by other anions (Cl-, NO , SO4(2)-, I- ). The detection limit (S/N= 3) was 0.36 mg/L for IO(3)- . Relative standard deviation (RSD, n = 5) of chromatographic peak area and retention time were 0. 35% and 0. 28%, respectively. The proposed method was applied to the determination of trace iodate in iodized medicine. The spiked recovery of iodate was 96. 4%. The method is rapid, simple, accurate, reliable, and practical.

Method and apparatus for the selective separation of gaseous coal gasification products by pressure swing adsorption

DOEpatents

Ghate, Madhav R.; Yang, Ralph T.

1987-01-01

Bulk separation of the gaseous components of multi-component gases provided by the gasification of coal including hydrogen, carbon monoxide, methane, and acid gases (carbon dioxide plus hydrogen sulfide) are selectively adsorbed by a pressure swing adsorption technique using activated carbon, zeolite or a combination thereof as the adsorbent. By charging a column containing the adsorbent with a gas mixture and pressurizing the column to a pressure sufficient to cause the adsorption of the gases and then reducing the partial pressure of the contents of the column, the gases are selectively and sequentially desorbed. Hydrogen, the least absorbable gas of the gaseous mixture, is the first gas to be desorbed and is removed from the column in a co-current direction followed by the carbon monoxide, hydrogen and methane. With the pressure in the column reduced to about atmospheric pressure the column is evacuated in a countercurrent direction to remove the acid gases from the column. The present invention is particularly advantageous as a producer of high parity hydrogen from gaseous products of coal gasification and as an acid gas scrubber.

Separation of carbon nanotubes into chirally enriched fractions

DOEpatents

Doorn, Stephen K [Los Alamos, NM; Niyogi, Sandip [Los Alamos, NM

2012-04-10

A mixture of single-walled carbon nanotubes ("SWNTs") is separated into fractions of enriched chirality by preparing an aqueous suspension of a mixture of SWNTs and a surfactant, injecting a portion of the suspension on a column of separation medium having a density gradient, and centrifuging the column. In some embodiments, salt is added prior to centrifugation. In other embodiments, the centrifugation is performed at a temperature below room temperature. Fractions separate as colored bands in the column. The diameter of the separated SWNTs decreases with increasing density along the gradient of the column. The colored bands can be withdrawn separately from the column.

METHOD OF OPERATING A HEAVY WATER MODERATED REACTOR

DOEpatents

Vernon, H.C.

1962-08-14

A method of removing fission products from the heavy water used in a slurry type nuclear reactor is described. According to the process the slurry is steam distilled with carbon tetrachloride so that at least a part of the heavy water and carbon tetrachloride are vaporized; the heavy water and carbon tetrachloride are separated; the carbon tetrachloride is returned to the steam distillation column at different points in the column to aid in depositing the slurry particles at the bottom of the column; and the heavy water portion of the condensate is purified. (AEC)

High performance liquid chromatographic method for the determination of cetirizine and ambroxol in human plasma and urine--a boxcar approach.

PubMed

Dharuman, J; Vasudhevan, M; Ajithlal, T

2011-09-01

A column switching high performance liquid chromatographic method with estimable sensitivity and accuracy was developed for the determination of cetirizine and ambroxol in human plasma using nebivolol as the internal standard. Plasma samples were prepared by liquid-liquid extraction in methylene chloride and a mixture of diethylether (80:20, v/v). The extracted samples were injected into a multifunctional clean-up column Supelcosil LCABZ (50 mm × 4.6 mm, 5 μm particle size) using mobile phase 1 comprising acetonitrile-phosphate buffer (pH 3.5; 20 mM) (20:80, v/v). The eluate of cetirizine and ambroxol were separated to an analytical Kromasil C(8) micro bore column (50 mm × 0.3 mm, 5 μm particle size) via a column switching device. A Kromasil C(18) analytical column (250 mm × 2.1 mm, 5 μm particle size) was used as a separation column. Mobile phase 2 consisting acetonitrile-triethylamine (0.5%) in phosphate buffer (pH 3.5; 20mM) (55:45, v/v) was used for the compound elution. The eluents were detected at 230 nm with photodiode array detector. An aliquot of 150 μl of plasma sample was introduced into the pretreatment column via the auto sampler using mobile phase 1 at a flow rate of 0.5 ml/min, column switching valve being positioned at A. The pretreatment column retained cetirizine, ambroxol and nebivolol (IS) in the column leaving the residual proteins of plasma eluted in void volume and drained out. The switching valve was shifted to position B at 7.5 min. Cetirizine, ambroxol and IS were eluted from the pretreatment column between 7. 5 and 11.5 min and introduced to the concentration column. Finally, cetirizine, ambroxol and IS were introduced to the separation column by switching valve using mobile phase 2 at a flow rate of 0.4 ml/min. During the analysis the pretreatment column was washed for the next analysis and resume to the position A. The total run time was 25 min for a sample. The procedure was repeated for urine analysis also. The method was linear from 2 to 450 ng/ml and 7-300 ng/ml for cetirizine and ambroxol respectively in plasma and 1-500 ng/ml and 5-400 ng/ml, respectively for cetirizine and ambroxol in urine. Intra-day and inter-day precision of cetirizine and ambroxol was below 15% in terms of coefficient of variation and accuracy of cetirizine and ambroxol was ranged from 94 to 101.6% and 91.1 to 100.2%, respectively. The method demonstrated high sensitivity and selectivity and therefore, applied to evaluate pharmacokinetics of cetirizine and ambroxol in healthy human volunteer after a single oral administration. Urine samples obtained from healthy human volunteers and clinical subjects with renal impairment have also been analyzed by the method to compare the elimination pattern. The method was precise and accurate for the estimation of cetirizine and ambroxol both in blood and in urine. Copyright © 2011 Elsevier B.V. All rights reserved.

An automated HPLC method for the fractionation of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans in fish tissue on a porous graphitic carbon column

USGS Publications Warehouse

Echols, Kathy R.; Gale, Robert W.; Tillitt, Donald E.; Schwartz, Ted R.; O'Laughlin, Jerome

1997-01-01

The Ah (aryl-hydrocarbon) hydroxylase-receptor active polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were fractionated by an automated high-performance liquid chromatography (HPLC) system using the Hypercarb™ porous graphitic carbon (PGC) column. This commercially available column was used to fractionate the di-, mono-, and non-ortho PCBs into three fractions for gas chromatography (GC)/electron capture detection analysis, and a fourth fraction containing the PCDDs/PCDFs for GC/mass spectrometry analysis. The recoveries of the PCBs ranged from 68 to 96%, and recoveries of the PCDDs/PCDFs ranged from 74 to 123%. The PGC column has the advantage of faster separations (110 min versus 446 min) and less solvent use (275 ml versus 1,100 ml) compared with automated fractionation of these compounds on activated carbon (PX-21), while still affording good separation of the classes. The PGC column may have an advantage over the pyrenyl-based HPLC method because it has a greater loading capacity (400 μg total PCBs versus 250 μg). Overall, the PGC is a standard column that provides reproducible fractionation of PCDD/PCDFs and PCBs for analytical measurement in environmental samples.

Preparative separation of the polar part from the rhizomes of Anemarrhena asphodeloides using a hydrophilic C18 stationary phase.

PubMed

Cai, Jianfeng; Xin, Huaxia; Cheng, Lingping; Fu, YanHui; Jiang, Dasen; Feng, Jiatao; Fu, Qing; Jin, Yu; Liang, Xinmiao

2017-09-15

The goal of this study was to develop a method that utilized a hydrophilic C18 stationary phase in the preparative high performance liquid chromatography to isolate the polar part from the rhizomes of Anemarrhena asphodeloides. The results showed that an initial mobile phase of pure water for the separation could greatly increase the retention and solubility of the polar compounds at the preparative scale. Introducing polar groups on the surface of the hydrophilic C18 column together with the use of optimized mobile phase compositions improved the column separation selectivity for polar compounds. Eleven previously undescribed compounds in Anemarrhena asphodeloides were obtained, indicating that the method developed in this study would facilitate the purification and separation of the polar part of traditional Chinese medicines. Copyright © 2017 Elsevier B.V. All rights reserved.

The Effect of Column and Eluent Fluorination on the Retention and Separation of non-Fluorinated Amino Acids and Proteins by HPLC

PubMed Central

Joyner, Katherine; Wang, Weizhen; Yu, Yihua Bruce

2011-01-01

The effect of column and eluent fluorination on the retention and separation of non-fluorinated amino acids and proteins in HPLC is investigated. A side-by-side comparison of fluorocarbon column and eluents (F-column and F-eluents) with their hydrocarbon counterparts (H-column and H-eluents) in the separation of a group of 33 analytes, including 30 amino acids and 3 proteins, is conducted. The H-column and the F-column contain the n-C8H17 group and n-C8F17 group, respectively, in their stationary phases. The H-eluents include ethanol (EtOH) and isopropanol (ISP) while the F-eluents include trifluoroethanol (TFE) and hexafluorosopropanol (HFIP). The 2 columns and 4 eluents generated 8 (column, eluent) pairs that produce 264 retention time data points for the 33 analytes. A statistical analysis of the retention time data reveals that although the H-column is better than the F-column in analyte separation and H-eluents are better than F-eluents in analyte retention, the more critical factor is the proper pairing of column with eluent. Among the conditions explored in this project, optimal retention and separation is achieved when the fluorocarbon column is paired with ethanol, even though TFE is the most polar one among the 4 eluents. This result shows fluorocarbon columns have much potential in chromatographic analysis and separation of non-fluorinated amino acids and proteins. PMID:21318121

Enhancing Centrifugal Separation With Electrophoresis

NASA Technical Reports Server (NTRS)

Herrmann, F. T.

1986-01-01

Separation of biological cells by coil-planet centrifuge enhanced by electrophoresis. By itself, coil-planet centrifuge offers relatively gentle method of separating cells under low centrifugal force in physiological medium that keeps cells alive. With addition of voltage gradient to separation column of centrifuge, separation still gentle but faster and more complete. Since separation apparatus contains no rotary seal, probability of leakage, contamination, corrosion, and short circuits reduced.

Optimized anion exchange column isolation of zirconium-89 ( 89Zr) from yttrium cyclotron target: Method development and implementation on an automated fluidic platform

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

O’Hara, Matthew J.; Murray, Nathaniel J.; Carter, Jennifer C.

Zirconium-89 ( 89Zr), produced by the (p, n) reaction from naturally monoisotopic yttrium ( natY), is a promising positron emitting isotope for immunoPET imaging. Its long half-life of 78.4 h is sufficient for evaluating slow physiological processes. A prototype automated fluidic system, coupled to on-line and in-line detectors, has been constructed to facilitate development of new 89Zr purification methodologies. The highly reproducible reagent delivery platform and near-real time monitoring of column effluents allows for efficient method optimization. The separation of Zr from dissolved Y metal targets was evaluated using several anion exchange resins. Each resin was evaluated against its abilitymore » to quantitatively capture Zr from a load solution high in dissolved Y. The most appropriate anion exchange resin for this application was identified, and the separation method was optimized. The method is capable of a high Y decontamination factor (>10 5) and has been shown to remove Fe, an abundant contaminant in Y foils, from the 89Zr elution fraction. Finally, the method was evaluated using cyclotron bombarded Y foil targets; the method was shown to achieve >95% recovery of the 89Zr present in the foils. The anion exchange column method described here is intended to be the first 89Zr isolation stage in a dual-column purification process.« less

Optimized anion exchange column isolation of zirconium-89 ( 89Zr) from yttrium cyclotron target: Method development and implementation on an automated fluidic platform

DOE PAGES

O’Hara, Matthew J.; Murray, Nathaniel J.; Carter, Jennifer C.; ...

2018-02-24

Zirconium-89 ( 89Zr), produced by the (p, n) reaction from naturally monoisotopic yttrium ( natY), is a promising positron emitting isotope for immunoPET imaging. Its long half-life of 78.4 h is sufficient for evaluating slow physiological processes. A prototype automated fluidic system, coupled to on-line and in-line detectors, has been constructed to facilitate development of new 89Zr purification methodologies. The highly reproducible reagent delivery platform and near-real time monitoring of column effluents allows for efficient method optimization. The separation of Zr from dissolved Y metal targets was evaluated using several anion exchange resins. Each resin was evaluated against its abilitymore » to quantitatively capture Zr from a load solution high in dissolved Y. The most appropriate anion exchange resin for this application was identified, and the separation method was optimized. The method is capable of a high Y decontamination factor (>10 5) and has been shown to remove Fe, an abundant contaminant in Y foils, from the 89Zr elution fraction. Finally, the method was evaluated using cyclotron bombarded Y foil targets; the method was shown to achieve >95% recovery of the 89Zr present in the foils. The anion exchange column method described here is intended to be the first 89Zr isolation stage in a dual-column purification process.« less

[Research on chemical constituents from stem of Gymnema sylvestre].

PubMed

Zhen, Han-shen; Zhu, Xue-yan; Lu, Ru-mei; Liang, Jie; Qiu, Qin; Meng, Qi-miao

2008-08-01

To study on the chemical constituents from the stem of Gymnema sylvestre. The constituents were extracted by percolation with ethanol. Then the extract was separated by systemic solvent separation methods. The part of n-butanol extract was isolated and purified by macroporous adsorptive resins, silica gel column chromatography, sephadex gel column chromatography and recrystallization. The isolated compounds were identified by spectrum methods. Eight compounds were isolated and identified as fallows: Conduritol A(I), 1-Heptadecanol(II), Stigmasterol glucoside(III), 1-Quercitol(IV), 1-Octadecanol(V), Potassium nitrate(VI), Lupeol cinnamate(VII), Stigmasterol(VIII). Chemical compounds II, III, V, VII are firstly obtained from this plant.

New approaches with two cyano columns to the separation of acetaminophen, phenylephrine, chlorpheniramine and related compounds.

PubMed

Olmo, B; García, A; Marín, A; Barbas, C

2005-03-25

The development of new pharmaceutical forms with classical active compounds generates new analytical problems. That is the case of sugar-free sachets of cough-cold products containing acetaminophen, phenylephrine hydrochloride and chlorpheniramine maleate. Two cyanopropyl stationary phases have been employed to tackle the problem. The Discovery cyanopropyl (SUPELCO) column permitted the separation of the three actives, maleate and excipients (mainly saccharine and orange flavour) with a constant proportion of aqueous/ organic solvent (95:5, v/v) and a pH gradient from 7.5 to 2. The run lasted 14 min. This technique avoids many problems related to baseline shifts with classical organic solvent gradients and opens great possibilities to modify selectivity not generally used in reversed phase HPLC. On the other hand, the Agilent Zorbax SB-CN column with a different retention profile permitted us to separate not only the three actives and the excipients but also the three known related compounds: 4-aminophenol, 4-chloracetanilide and 4-nitrophenol in an isocratic method with a run time under 30 min. This method was validated following ICH guidelines and validation parameters showed that it could be employed as stability-indicating method for this pharmaceutical form.

Fast analysis of capsaicinoids in Naga Jolokia extracts (Capsicum chinense) by high-performance liquid chromatography using fused core columns.

PubMed

Stipcovich, Tea; Barbero, Gerardo F; Ferreiro-González, Marta; Palma, Miguel; Barroso, Carmelo G

2018-01-15

A rapid high-performance liquid chromatography method with a C18 reverse-phase fused-core column has been developed for the determination and quantification of the main capsaicinoids (nornordihydrocapsaicin, nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin) present in Naga Jolokia peppers. A fused-core Kinetex™ C18 column (50×2.1mm i.d.; 2.6μm) was used for the analysis. The chromatographic separation was obtained with a gradient method in which the mobile phase was water (0.1% acetic acid) as solvent A and acetonitrile (0.1% acetic acid) as solvent B. The separation of all compounds was achieved in less than 3min with a total analysis time (sample-to-sample) of 10min. The robustness of the method was evaluated. The method showed excellent repeatability and intermediate precision expressed as coefficient of variance of less than 2%. The developed method was employed for the quantification of the major capsaicinoids present in different peppers and commercial products containing chilli peppers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analytical method development for directed enzyme evolution research: a high throughput high-performance liquid chromatography method for analysis of ribose and ribitol and a capillary electrophoresis method for the separation of ribose enantiomers.

PubMed

Sun, Baoguo; Miller, Gregory; Lee, Wan Yee; Ho, Kelvin; Crowe, Michael A; Partridge, Leslie

2013-01-04

Analytical methods were developed for a directed enzyme evolution research programme, which pursued high performance enzymes to produce high quality L-ribose using large scale biocatalytic reaction. A high throughput HPLC method with evaporative light-scattering detection was developed to test ribose and ribitol in the enzymatic reaction, a β-cyclobond 2000 analytical column separated ribose and ribitol in 2.3 min, a C(18) guard column was used as an on-line filter to clean up the enzyme sample matrix and a short gradient was applied to wash the column, the enzymatic reaction solution can be directly injected after quenching. Total run time of each sample was approx. 4 min which provided capability of screening 4×96-well plates/day/instrument. Meanwhile, a capillary electrophoresis method was developed for the separation of ribose enantiomers, while 7-aminonaphthalene-1,3-disulfonic acid was used as derivatisation reagent and 25 mM tetraborate with 5 mM β-cyclodextrin was used as electrolyte. 0.35%of D-ribose in L-ribose can be detected which can be translated into 99.3% ee of L-ribose. Derivatisation reagent and sample matrix did not interfere with the measurement. Copyright © 2012 Elsevier B.V. All rights reserved.

Separation, isolation and stereochemical assignment of imazalil enantiomers and their quantitation in an in vitro toxicity test.

PubMed

Casas, Mònica Escolà; Kretschmann, Andreas Christopher; Andernach, Lars; Opatz, Till; Bester, Kai

2016-06-24

A simple method for the separation of the enantiomers of the fungicide imazalil was developed. Racemic imazalil was separated into its enantiomers with an enantiomeric purity of 99% using HPLC-UV with an enantioselective column (permethylated cyclodextrin) operated in reversed phase mode (water with 0.2% trimethylamine and 0.08% acetic acid and methanol). The absolute configuration of the separated enantiomers was assigned and unequivocally confirmed by optical rotation as well as by vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) combined with ab-initio calculations. The same enantioselective column was also used to develop an HPLC-MS/MS method for the quantification of imazalil enantiomers. The HPLC-MS/MS method reached limits of quantification (LOQs) of 0.025mg/mL with 5μL injections. This method was used to verify imazalil concentrations and enantiomeric fractions in samples from an in vitro test on effects on human steroidogenesis (H295R steroidogenesis assay). The quantification verified the stability of the enantiomers of imazalil during the in vitro tests. Copyright © 2016 Elsevier B.V. All rights reserved.

Sequential Injection Chromatography with an Ultra-short Monolithic Column for the Low-Pressure Separation of α-Tocopherol and γ-Oryzanol in Vegetable Oils and Nutrition Supplements.

PubMed

Thaithet, Sujitra; Kradtap Hartwell, Supaporn; Lapanantnoppakhun, Somchai

2017-01-01

A low-pressure separation procedure of α-tocopherol and γ-oryzanol was developed based on a sequential injection chromatography (SIC) system coupled with an ultra-short (5 mm) C-18 monolithic column, as a lower cost and more compact alternative to the HPLC system. A green sample preparation, dilution with a small amount of hexane followed by liquid-liquid extraction with 80% ethanol, was proposed. Very good separation resolution (R s = 3.26), a satisfactory separation time (10 min) and a total run time including column equilibration (16 min) were achieved. The linear working range was found to be 0.4 - 40 μg with R 2 being more than 0.99. The detection limits of both analytes were 0.28 μg with the repeatability within 5% RSD (n = 7). Quantitative analyses of the two analytes in vegetable oil and nutrition supplement samples, using the proposed SIC method, agree well with the results from HPLC.

ANION EXCHANGE METHOD FOR SEPARATION OF METAL VALUES

DOEpatents

Hyde, E.K.; Raby, B.A.

1959-02-10

A method is described for selectively separating radium, bismuth, poloniums and lead values from a metallic mixture of thc same. The mixture is dissolved in aqueous hydrochloric acid and the acidity is adjusted to between 1 to 2M in hydrochloric acid to form the anionic polychloro complexes of polonium and bismuth. The solution is contacted with a first anion exchange resin such as strong base quaternary ammonia type to selectively absorb the polonium and bismuth leaving the radium and lead in the effluent. The effluent, after treatment in hydrochloric acid to increase the hydrochloric acid concentration to 6M is contacted with a second anion exchange iesin of the same type as the above to selectively adsorb the lead leaving the radium in the effluent. Radium is separately recovered from the effluent from the second exchange column. Lead is stripped from the loaded resin of the second column by treatment with 3M hydrochloric acid solution. The loaded resin of the first column is washed with 8M hydrochloric acid solution to recover bismuth and then treated with strong nitric acid solution to recover polonium.

Rapid Column-Free Enrichment of Mononuclear Cells from Solid Tissues

PubMed Central

Scoville, Steven D.; Keller, Karen A.; Cheng, Stephanie; Zhang, Michael; Zhang, Xiaoli; Caligiuri, Michael A.; Freud, Aharon G.

2015-01-01

We have developed a rapid negative selection method to enrich rare mononuclear cells from human tissues. Unwanted and antibody-tethered cells are selectively depleted during a Ficoll separation step, and there is no need for magnetic-based reagents and equipment. The new method is fast, customizable, inexpensive, remarkably efficient, and easy to perform, and per sample the overall cost is less than one-tenth the cost associated with a magnetic column-based method. PMID:26223896

Resolution of common dietary sugars from probe sugars for test of intestinal permeability using capillary column gas chromatography.

PubMed

Farhadi, Ashkan; Keshavarzian, Ali; Fields, Jeremy Z; Sheikh, Maliha; Banan, Ali

2006-05-19

The most widely accepted method for the evaluation of intestinal barrier integrity is the measurement of the permeation of sugar probes following an oral test dose of sugars. The most-widely used sugar probes are sucrose, lactulose, mannitol and sucralose. Measuring these sugars using a sensitive gas chromatographic (GC) method, we noticed interference on the area of the lactulose and mannitol peaks. We tested different sugars to detect the possible makeup of these interferences and finally detected that the lactose interferes with lactulose peak and fructose interferes with mannitol peak. On further developing of our method, we were able to reasonably separate these peaks using different columns and condition for our assay. Sample preparation was rapid and simple and included adding internal standard sugars, derivitization and silylation. We used two chromatographic methods. In the first method we used Megabore column and had a run time of 34 min. This resulted in partial separation of the peaks. In the second method we used thin capillary column and was able to reasonably separate the lactose and lactulose peaks and the mannitol and fructose peaks with run time of 22 min. The sugar probes including mannitol, sucrose, lactulose, sucralose, fructose and lactose were detected precisely, without interference. The assay was linear between lactulose concentrations of 0.5 and 40 g/L (r(2)=1.000, P<0.0001) and mannitol concentrations of 0.01 and 40 g/L (r(2)=1.000). The sensitivity of this method remained high using new column and assay condition. The minimum detectable concentration calculated for both methods was 0.5 mg/L for lactulose and 1 mg/L for mannitol. This is the first report of interference of commonly used sugars with test of intestinal permeability. These sugars are found in most of fruits and dairy products and could easily interfere with the result of permeability tests. Our new GC assay of urine sugar probes permits the simultaneous quantitation of sucralose, sucrose, mannitol and lactulose, without interference with lactose and fructose. This assay is a rapid, simple, sensitive and reproducible method to accurately measure intestinal permeability.

Simultaneous separation and analysis of water- and fat-soluble vitamins on multi-modal reversed-phase weak anion exchange material by HPLC-UV.

PubMed

Dabre, Romain; Azad, Nazanin; Schwämmle, Achim; Lämmerhofer, Michael; Lindner, Wolfgang

2011-04-01

Several methods for the separation of vitamins on HPLC columns were already validated in the last 20 years. However, most of the techniques focus on separating either fat- or water-soluble vitamins and only few methods are intended to separate lipophilic and hydrophilic vitamins simultaneously. A mixed-mode reversed-phase weak anion exchange (RP-WAX) stationary phase was developed in our laboratory in order to address such mixture of analytes with different chemical characteristics, which are difficult to separate on standard columns. The high versatility in usage of the RP-WAX chromatographic material allowed a baseline separation of ten vitamins within a single run, seven water-soluble and three fat-soluble, using three different chromatographic modes: some positively charged vitamins are eluted in ion exclusion and ion repulsion modes whereas the negatively charged molecules are eluted in the ion exchange mechanism. The non-charged molecules are eluted in a classical reversed-phase mode, regarding their polarities. The method was validated for the vitamin analysis in tablets, evaluating selectivity, robustness, linearity, accuracy, and precision. The validated method was finally employed for the analysis of the vitamin content of some commercially available supplement tablets. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of separation properties of a modified strong cation exchange material named MEX and its application in 2D-MEX × C18 system to separate peptides from scorpion venom.

PubMed

Chen, Bo; Xu, Junyan; Fu, Qing; Dong, Xuefang; Guo, Zhimou; Jin, Yu; Liang, Xinmiao

2015-07-07

Peptides from scorpion venom represent one of the most promising drug sources for drug discovery for some specific diseases. Current challenges in their separation include high complexity, high homologies and the huge range of peptides. In this paper, a modified strong cation exchange material, named MEX, was utilised for the two-dimensional separation of peptides from complex scorpion venom. The silica-based MEX column was bonded with two functional groups; benzenesulfonic acid and cyanopropyl. To better understand its separation mechanisms, seven standard peptides with different properties were employed in an evaluation study, the results of which showed that two interactions were involved in the MEX column: electrostatic interactions based on benzenesulfonic acid groups dominated the separation of peptides; weak hydrophobic interactions introduced by cyanopropyl groups increased the column's selectivity for peptides with the same charge. This characteristic allowed the MEX column to overcome some of the drawbacks of traditional strong cation exchange (SCX) columns. Furthermore, the study showed the great effects of the acetonitrile (ACN) content, the sodium perchlorate (NaClO4) concentration and the buffer pH in the mobile phase on the peptides' retention and separation selectivity on the MEX column. Subsequently, the MEX column was combined with a C18 column to establish an off-line 2D-MEX × C18 system to separate peptides from scorpion Buthus martensi Karsch (BmK) venom. Due to complementary separation mechanisms in each dimension, a high orthogonality of 47.62% was achieved. Moreover, a good loading capacity, excellent stability and repeatability were exhibited by the MEX column, which are beneficial for its use in future preparation experiments. Therefore, the MEX column could be an alternative to the traditional SCX columns for the separation of peptides from scorpion venom.

Demonstration of motionless Knudsen pump based micro-gas chromatography featuring micro-fabricated columns and on-column detectors.

PubMed

Liu, Jing; Gupta, Naveen K; Wise, Kensall D; Gianchandani, Yogesh B; Fan, Xudong

2011-10-21

This paper reports the investigation of a micro-gas chromatography (μGC) system that utilizes an array of miniaturized motionless Knudsen pumps (KPs) as well as microfabricated separation columns and optical detectors. A prototype system was built to achieve a flow rate of 1 mL min(-1) and 0.26 mL min(-1) for helium and dry air, respectively, when they were used as carrier gas. This system was then employed to evaluate GC performance compromises and demonstrate the ability to separate and detect gas mixtures containing analytes of different volatilities and polarities. Furthermore, the use of pressure programming of the KP array was demonstrated to significantly shorten the analysis time while maintaining a high detection resolution. Using this method, we obtained a high resolution detection of 5 alkanes of different volatilities within 5 min. Finally, we successfully detected gas mixtures of various polarities using a tandem-column μGC configuration by installing two on-column optical detectors to obtain complementary chromatograms.

Simultaneous LC determination of paracetamol and related compounds in pharmaceutical formulations using a carbon-based column.

PubMed

Monser, Lotfi; Darghouth, Frida

2002-03-01

A simple, rapid and convenient high performance liquid chromatographic method, which permits the simultaneous determination of paracetamol, 4-aminophenol and 4-chloracetanilide in pharmaceutical preparation has been developed. The chromatographic separation was achieved on porous graphitized carbon (PGC) column using an isocratic mixture of 80/20 (v/v) acetonitrile/0.05 M potassium phosphate buffer (pH 5.5) and ultraviolet detection at 244 nm. Correlation coefficient for calibration curves in the ranges 1-50 microg ml(-1) for paracetamol and 5-40 microg ml(-1) for 4-aminophenol and 4-chloroacetanilide were >0.99. The sensitivity of detection is 0.1 microg ml(-1) for paracetamol and 0.5 microg ml(-1) for 4-aminophenol and 4-chloroacetanilide. The proposed liquid chromatographic method was successfully applied to the analysis of commercially available paracetamol dosage forms with recoveries of 98-103%. It is suggested that the proposed method should be used for routine quality control and dosage form assay of paracetamol in pharmaceutical preparations. The chromatographic behaviour of the three compounds was examined under variable mobile phase compositions and pH, the results revealed that selectivity was dependent on the organic solvent and pH used. The retention selectivity of these compounds on PGC was compared with those of octadecylsilica (ODS) packing materials in reversed phase liquid chromatography. The ODS column gave little separation for the degradation product (4-aminophenol) from paracetamol, whereas PGC column provides better separation in much shorter time.

Preparation of diclofenac-imprinted polymer beads for selective molecular separation in water.

PubMed

Zhou, Tongchang; Kamra, Tripta; Ye, Lei

2018-03-01

Molecular imprinting technique is an attractive strategy to prepare materials for target recognition and rapid separation. In this work, a new type of diclofenac (DFC)-imprinted polymer beads was synthesized by Pickering emulsion polymerization using 2-(dimethylamino)ethyl methacrylate as the functional monomer. The selectivity and capacity of the molecularly imprinted polymers (MIPs) were investigated in aqueous solution. Equilibrium binding results show that the MIPs have a high selectivity to bind DFC in a wide range of pH values. Moreover, in liquid chromatography experiment, the imprinted polymer beads were packed into column to investigate the binding selectivity under nonequilibrium conditions. The retention time of DFC on the MIP column is significantly longer than its structural analogues. Also, retention of DFC on the MIP column was significantly longer than on the nonimprinted polymer column under aqueous condition. As the new MIP beads can be used to achieve direct separation of DFC from water, the synthetic method and the affinity beads developed in this work opened new possibilities for removing toxic chemicals from environmental and drinking water. Copyright © 2017 John Wiley & Sons, Ltd.

Signal Enhancement in HPLC/Micro-Coil NMR Using Automated Column Trapping

PubMed Central

Djukovic, Danijel; Liu, Shuhui; Henry, Ian; Tobias, Brian; Raftery, Daniel

2008-01-01

A new HPLC-NMR system is described that performs analytical separation, pre-concentration, and NMR spectroscopy in rapid succession. The central component of our method is the online pre-concentration sequence that improves the match between post-column analyte peak volume and the micro-coil NMR detection volume. Separated samples are collected on to a C18 guard column with a mobile phase composed of 90% D2O/10% acetonitrile-D3, and back-flashed to the NMR micro-coil probe with 90% acetonitrile-D3/10% D2O. In order to assess the performance of our unit, we separated a standard mixture of 1 mM ibuprofen, naproxen, and phenylbutazone using a commercially available C18 analytical column. The S/N measurements from the NMR acquisitions indicated that we achieved signal enhancement factors up to 10.4 (±1.2)-fold. Furthermore, we observed that pre-concentration factors increased as the injected amount of analyte decreased. The highest concentration enrichment of 14.7 (±2.2)-fold was attained injecting 100 μL solution of 0.2 mM (~4 μg) ibuprofen. PMID:17037915

Method and apparatus for the selective separation of gaseous coal gasification products by pressure swing adsorption

DOEpatents

Ghate, M.R.; Yang, R.T.

1985-10-03

Bulk separation of the gaseous components of multi-component gases provided by the gasification of coal including hydrogen, carbon monoxide, methane, and acid gases (carbon dioxide plus hydrogen sulfide) are selectively adsorbed by a pressure swing adsorption technique using activated carbon zeolite or a combination thereof as the adsorbent. By charging a column containing the adsorbent with a gas mixture and pressurizing the column to a pressure sufficient to cause the adsorption of the gases and then reducing the partial pressure of the contents of the column, the gases are selectively and sequentially desorbed. Hydrogen, the least absorbable gas of the gaseous mixture, is the first gas to be desorbed and is removed from the column in a co-current direction followed by the carbon monoxide, hydrogen and methane. With the pressure in the column reduced to about atmospheric pressure the column is evacuated in a countercurrent direction to remove the acid gases from the column. The present invention is particularly advantageous as a producer of high purity hydrogen from gaseous products of coal gasification and as an acid gas scrubber. 2 figs., 2 tabs.

Quantitative separation of tetralin hydroperoxide from its decomposition products by high performance liquid chromatography

NASA Technical Reports Server (NTRS)

Worstell, J. H.; Daniel, S. R.

1981-01-01

A method for the separation and analysis of tetralin hydroperoxide and its decomposition products by high pressure liquid chromatography has been developed. Elution with a single, mixed solvent from a micron-Porasil column was employed. Constant response factors (internal standard method) over large concentration ranges and reproducible retention parameters are reported.

Rapid sequential determination of Pu, 90Sr and 241Am nuclides in environmental samples using an anion exchange and Sr-Spec resins.

PubMed

Lee, M H; Ahn, H J; Park, J H; Park, Y J; Song, K

2011-02-01

This paper presents a quantitative and rapid method of sequential separation of Pu, (90)Sr and (241)Am nuclides in environmental soil samples with an anion exchange resin and Sr Spec resin. After the sample solution was passed through an anion exchange column connected to a Sr Spec column, Pu isotopes were purified from the anion exchange column. Strontium-90 was separated from other interfering elements by the Sr Spec column. Americium-241 was purified from lanthanides by the anion exchange resin after oxalate co-precipitation. Measurement of Pu and Am isotopes was carried out using an α-spectrometer. Strontium-90 was measured by a low-level liquid scintillation counter. The radiochemical procedure of Pu, (90)Sr and (241)Am nuclides investigated in this study validated by application to IAEA reference materials and environmental soil samples. Copyright © 2010 Elsevier Ltd. All rights reserved.

High performance liquid chromatography column efficiency enhancement by zero dead volume recycling and practical approach using park and recycle arrangement.

PubMed

Minarik, Marek; Franc, Martin; Minarik, Milan

2018-06-15

A new instrumental approach to recycling HPLC is described. The concept is based on fast reintroduction of incremental peak sections back onto the separation column. The re-circulation is performed within a closed loop containing only the column and two synchronized switching valves. By having HPLC pump out of the cycle, the method minimizes peak broadening due to dead volume. As a result the efficiency is dramatically increased allowing for the most demanding analytical applications. In addition, a parking loop is employed for temporary storage of analytes from the middle section of the separated mixture prior to their recycling. Copyright © 2018 Elsevier B.V. All rights reserved.

The design of a new concept chromatography column.

PubMed

Camenzuli, Michelle; Ritchie, Harald J; Ladine, James R; Shalliker, R Andrew

2011-12-21

Active Flow Management is a new separation technique whereby the flow of mobile phase and the injection of sample are introduced to the column in a manner that allows migration according to the principles of the infinite diameter column. A segmented flow outlet fitting allows for the separation of solvent or solute that elutes along the central radial section of the column from that of the sample or solvent that elutes along the wall region of the column. Separation efficiency on the analytical scale is increased by 25% with an increase in sensitivity by as much as 52% compared to conventional separations.

Performances of CN-columns for the analysis of γ-oryzanol and its p-coumarate and caffeate derivatives by normal phase HPLC and a validated method of quantitation.

PubMed

D'Ambrosio, Michele

2013-06-15

γ-Oryzanol is an important phytochemical used in pharmaceutical, alimentary and cosmetic preparations. The present article, for the first time, discloses the performances of NP-HPLC in separating γ-oryzanol components and develops a validated method for its routine quantification. The analysis is performed on a cyanopropyl bonded column using the hexane/MTBE gradient elution and UV detection at 325 nm. The method allows: the separation of steryl ferulate, p-coumarate and caffeate esters, the separation of cis- from trans-ferulate isomers, the splitting of steroid moieties into saturated and unsaturated at the side chain. The optimised method provides excellent linear response (R(2)=0.99997), high precision (RSD<1.0%) and satisfactory accuracy (R(∗)=70-86%). In conclusion, the established method presents the details of the procedure and the experimental conditions in order to achieve the required precision and instrumental accuracy. The method is fast and sensitive and it could be a suitable tool for quality assurance and determination of origin. Copyright © 2012 Elsevier Ltd. All rights reserved.

Green Chromatographic Separation of Coumarin and Vanillins Using Subcritical Water as the Mobile Phase.

PubMed

Kayan, Berkant; Akay, Sema; Yang, Yu

2016-08-01

Pure water was used as the eluent for separation of coumarin, vanillin and ethyl vanillin at temperatures ranging from 100 to 200°C using a homemade subcritical water chromatography (SBWC) system. Chromatographic separations were performed on five commercial columns including XTerra MS C18, XBridge C18, Zorbax RRHD Eclipse Plus, Zorbax SB-Phenyl and Zorbax SB-C18 columns. The retention time of all three solutes decreased with increasing water temperature. The shortest retention time among all acceptable separations, less than 4 min, was achieved on the Zorbax SB-C18 column at 200°C. While separations on the XTerra MS C18 column resulted in fronting peaks and a degradation peak from ethyl vanillin on the Zorbax RRHD Eclipse Plus column was observed, all three other columns yielded reasonable separations under SBWC conditions. In addition to separation of the standard test mixture, separation of coumarin contained in a skincare cream sample was also carried out using SBWC. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simulation of elution profiles in liquid chromatography - II: Investigation of injection volume overload under gradient elution conditions applied to second dimension separations in two-dimensional liquid chromatography.

PubMed

Stoll, Dwight R; Sajulga, Ray W; Voigt, Bryan N; Larson, Eli J; Jeong, Lena N; Rutan, Sarah C

2017-11-10

An important research direction in the continued development of two-dimensional liquid chromatography (2D-LC) is to improve the detection sensitivity of the method. This is especially important in applications where injection of large volumes of effluent from the first dimension ( 1 D) column into the second dimension ( 2 D) column leads to severe 2 D peak broadening and peak shape distortion. For example, this is common when coupling two reversed-phase columns and the organic solvent content of the 1 D mobile phase overwhelms the 2 D column with each injection of 1 D effluent, leading to low resolution in the second dimension. In a previous study we validated a simulation approach based on the Craig distribution model and adapted from the work of Czok and Guiochon [1] that enabled accurate simulation of simple isocratic and gradient separations with very small injection volumes, and isocratic separations with mismatched injection and mobile phase solvents [2]. In the present study we have extended this simulation approach to simulate separations relevant to 2D-LC. Specifically, we have focused on simulating 2 D separations where gradient elution conditions are used, there is mismatch between the sample solvent and the starting point in the gradient elution program, injection volumes approach or even exceed the dead volume of the 2 D column, and the extent of sample loop filling is varied. To validate this simulation we have compared results from simulations and experiments for 101 different conditions, including variation in injection volume (0.4-80μL), loop filling level (25-100%), and degree of mismatch between sample organic solvent and the starting point in the gradient elution program (-20 to +20% ACN). We find that that the simulation is accurate enough (median errors in retention time and peak width of -1.0 and -4.9%, without corrections for extra-column dispersion) to be useful in guiding optimization of 2D-LC separations. However, this requires that real injection profiles obtained from 2D-LC interface valves are used to simulate the introduction of samples into the 2 D column. These profiles are highly asymmetric - simulation using simple rectangular pulses leads to peak widths that are far too narrow under many conditions. We believe the simulation approach developed here will be useful for addressing practical questions in the development of 2D-LC methods. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of various types of stationary phases in non-aqueous reversed-phase high-performance liquid chromatography-mass spectrometry of glycerolipids in blackcurrant oil and its enzymatic hydrolysis mixture.

PubMed

Lísa, Miroslav; Holcapek, Michal; Sovová, Helena

2009-11-20

The selection of column packing during the development of high-performance liquid chromatography method is a crucial step to achieve sufficient chromatographic resolution of analyzed species in complex mixtures. Various stationary phases are tested in this paper for the analysis of complex mixture of triacylglycerols (TGs) in blackcurrant oil using non-aqueous reversed-phase (NARP) system with acetonitrile-2-propanol mobile phase. Conventional C(18) column in the total length of 45 cm is used for the separation of TGs according to their equivalent carbon number, the number and positions of double bonds and acyl chain lengths. The separation of TGs and their more polar hydrolysis products after the partial enzymatic hydrolysis of blackcurrant oil in one chromatographic run is achieved using conventional C(18) column. Retention times of TGs are reduced almost 10 times without the loss of the chromatographic resolution using ultra high-performance liquid chromatography with 1.7 microm C(18) particles. The separation in NARP system on C(30) column shows an unusual phenomenon, because the retention order of TGs changes depending on the column temperature, which is reported for the first time. The commercial monolithic column modified with C(18) is used for the fast analysis of TGs to increase the sample throughput but at cost of low resolution.

Enantiomeric separation of triazole fungicides with 3-μm and 5-μml particle chiral columns by reverse-phase high-performance liquid chromatography.

PubMed

Qiu, Jing; Dai, Shouhui; Zheng, Chuangmu; Yang, Shuming; Chai, Tingting; Bie, Mei

2011-07-01

This study used chiral columns packed with 3-μm and 5-μm particles to comparatively separate enantiomers of 9 triazole fungicides, and Lux Cellulose-1 columns with chiral stationary phase of cellulose-tris-(3,5-dimethylphenylcarbamate) were used on reverse-phase high-performance liquid chromatography with flow rates of 0.3 and 1.0 mL min(-1) for 3-μm and 5-μm columns, respectively. The (+)-enantiomers of hexaconazole (1), tetraconazole (4), myclobutanil (7), fenbuconazole (8) and the (-)-enantiomers of flutriafol (2), diniconazole (3), epoxiconazole (5), penconazole (6), triadimefon (9) were firstly eluted from both columns, the elution orders identified with an optical rotation detector didn't change with variety of column particles and mobile phases (acetronitrile/water and methanol/water). The plots of natural logarithms of the selectivity factors (ln α) for all fungicides except penconazole (6) versus the inverse of temperature (1/T) were linear in range of 5-40°C. The thermodynamic parameters (ΔH°, ΔS°, ΔΔH° and ΔΔS°) were calculated using Van't Hoff equations to understand the thermosynamic driving forces for enantioseparation. This work will be very helpful to obtain good enantiomeric separation and establish more efficient analytical method for triazole fungicides. Chirality, 2011. © 2011 Wiley-Liss, Inc. Copyright © 2011 Wiley-Liss, Inc.

Comprehensive two-dimensional HPLC to study the interaction of multiple components in Rheum palmatum L. with HSA by coupling a silica-bonded HSA column to a silica monolithic ODS column.

PubMed

Hu, Lianghai; Li, Xin; Feng, Shun; Kong, Liang; Su, Xingye; Chen, Xueguo; Qin, Feng; Ye, Mingliang; Zou, Hanfa

2006-04-01

A mode of comprehensive 2-D LC was developed by coupling a silica-bonded HSA column to a silica monolithic ODS column. This system combined the affinity property of the HSA column and the high-speed separation ability of the monolithic ODS column. The affinity chromatography with HSA-immobilized stationary phase was applied to study the interaction of multiple components in traditional Chinese medicines (TCMs) with HSA according to their affinity to protein in the first dimension. Then the unresolved components retained on the HSA column were further separated on the silica monolithic ODS column in the second dimension. By hyphenating the 2-D separation system to diode array detector and MS detectors, the UV and molecular weight information of the separated compounds can also be obtained. The developed separation system was applied to analysis of the extract of Rheum palmatum L., a number of low-abundant components can be separated on a single peak from the HSA column after normalization of peak heights. Six compounds were preliminarily identified according to their UV and MS spectra. It showed that this system was very useful for biological fingerprinting analysis of the components in TCMs and natural products.

Separation analysis of macrolide antibiotics with good performance on a positively charged C18HCE column.

PubMed

Wei, Jie; Shen, Aijin; Yan, Jingyu; Jin, Gaowa; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2016-03-01

The separation of basic macrolide antibiotics suffers from peak tailing and poor efficiency on traditional silica-based reversed-phase liquid chromatography columns. In this work, a C18HCE column with positively charged surface was applied to the separation of macrolides. Compared with an Acquity BEH C18 column, the C18HCE column exhibited superior performance in the aspect of peak shape and separation efficiency. The screening of mobile phase additives including formic acid, acetic acid and ammonium formate indicated that formic acid was preferable for providing symmetrical peak shapes. Moreover, the influence of formic acid content was investigated. Analysis speed and mass spectrometry compatibility were also taken into account when optimizing the separation conditions for liquid chromatography coupled with tandem mass spectrometry. The developed method was successfully utilized for the determination of macrolide residues in a honey sample. Azithromycin was chosen as the internal standard for the quantitation of spiramycin and tilmicosin, while roxithromycin was used for erythromycin, tylosin, clarithromycin, josamycin and acetylisovaleryltylosin. Good correlation coefficients (r(2) > 0.9938) for all macrolides were obtained. The intra-day and inter-day recoveries were 73.7-134.7% and 80.7-119.7% with relative standard deviations of 2.5-8.0% and 3.9-16.1%, respectively. Outstanding sensitivity with limits of quantitation (S/N ≥ 10) of 0.02-1 μg/kg and limits of detection (S/N ≥ 3) of 0.01-0.5 μg/kg were achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimized anion exchange column isolation of zirconium-89 (89Zr) from yttrium cyclotron target: Method development and implementation on an automated fluidic platform.

PubMed

O'Hara, Matthew J; Murray, Nathaniel J; Carter, Jennifer C; Morrison, Samuel S

2018-04-13

Zirconium-89 ( 89 Zr), produced by the (p, n) reaction from naturally monoisotopic yttrium ( nat Y), is a promising positron emitting isotope for immunoPET imaging. Its long half-life of 78.4 h is sufficient for evaluating slow physiological processes. A prototype automated fluidic system, coupled to on-line and in-line detectors, has been constructed to facilitate development of new 89 Zr purification methodologies. The highly reproducible reagent delivery platform and near-real time monitoring of column effluents allows for efficient method optimization. The separation of Zr from dissolved Y metal targets was evaluated using several anion exchange resins. Each resin was evaluated against its ability to quantitatively capture Zr from a load solution high in dissolved Y. The most appropriate anion exchange resin for this application was identified, and the separation method was optimized. The method is capable of a high Y decontamination factor (>10 5 ) and has been shown to remove Fe, an abundant contaminant in Y foils, from the 89 Zr elution fraction. Finally, the method was evaluated using cyclotron bombarded Y foil targets; the method was shown to achieve >95% recovery of the 89 Zr present in the foils. The anion exchange column method described here is intended to be the first 89 Zr isolation stage in a dual-column purification process. Copyright © 2018 Elsevier B.V. All rights reserved.

Miniaturized protein separation using a liquid chromatography column on a flexible substrate

NASA Astrophysics Data System (ADS)

Yang, Yongmo; Chae, Junseok

2008-12-01

We report a prototype protein separator that successfully miniaturizes existing technology for potential use in biocompatible health monitoring implants. The prototype is a liquid chromatography (LC) column (LC mini-column) fabricated on an inexpensive, flexible, biocompatible polydimethylsiloxane (PDMS) enclosure. The LC mini-column separates a mixture of proteins using size exclusion chromatography (SEC) with polydivinylbenzene beads (5-20 µm in diameter with 10 nm pore size). The LC mini-column is smaller than any commercially available LC column by a factor of ~11 000 and successfully separates denatured and native protein mixtures at ~71 psi of the applied fluidic pressure. Separated proteins are analyzed using NuPAGE-gel electrophoresis, high-performance liquid chromatography (HPLC) and an automated electrophoresis system. Quantitative HPLC results demonstrate successful separation based on intensity change: within 12 min, the intensity between large and small protein peaks changed by a factor of ~20. In further evaluation using the automated electrophoresis system, the plate height of the LC mini-column is between 36 µm and 100 µm. The prototype LC mini-column shows the potential for real-time health monitoring in applications that require inexpensive, flexible implant technology that can function effectively under non-laboratory conditions.

Investigation of transient cavitating flow in viscoelastic pipes

NASA Astrophysics Data System (ADS)

Keramat, A.; Tijsseling, A. S.; Ahmadi, A.

2010-08-01

A study on water hammer in viscoelastic pipes when the fluid pressure drops to liquid vapour pressure is performed. Two important concepts including column separation and the effects of retarded strains in the pipe wall on the fluid response have been investigated separately in recent works, but there is some curiosity as to how the results for pressure and discharge are when column separation occurs in a viscoelastic pipe. For pipes made of plastic such as polyethylene (PE) and polyvinyl chloride (PVC), viscoelasticity is a crucial mechanical property which changes the hydraulic and structural transient responses. Based on previous developments in the analysis of water hammer, a model which is capable of analysing column separation in viscoelastic pipes is presented and used for solving the selected case studies. For the column-separation modelling the Discrete Vapour Cavity Model (DVCM) is utilised and the viscoelasticity property of the pipe wall is modelled by Kelvin-Voigt elements. The effects of viscoelasticity play an important role in the column separation phenomenon because it changes the water hammer fundamental frequency and so affects the time of opening or collapse of the cavities. Verification of the implemented computer code is performed for the effects of viscoelasticity and column separation - separately and simultaneously - using experimental results from the literature. In the provided examples the focus is placed on the simultaneous effect of viscoelasticity and column separation on the hydraulic transient response. The final conclusions drawn are that if rectangular grids are utilised the DVCM gives acceptable predictions of the phenomenon and that the pipe wall material's retarded behaviour strongly dampens the pressure spikes caused by column separation.

Recent Progress in Monolithic Silica Columns for High-Speed and High-Selectivity Separations.

PubMed

Ikegami, Tohru; Tanaka, Nobuo

2016-06-12

Monolithic silica columns have greater (through-pore size)/(skeleton size) ratios than particulate columns and fixed support structures in a column for chemical modification, resulting in high-efficiency columns and stationary phases. This review looks at how the size range of monolithic silica columns has been expanded, how high-efficiency monolithic silica columns have been realized, and how various methods of silica surface functionalization, leading to selective stationary phases, have been developed on monolithic silica supports, and provides information on the current status of these columns. Also discussed are the practical aspects of monolithic silica columns, including how their versatility can be improved by the preparation of small-sized structural features (sub-micron) and columns (1 mm ID or smaller) and by optimizing reaction conditions for in situ chemical modification with various restrictions, with an emphasis on recent research results for both topics.

Evaluation of injection methods for fast, high peak capacity separations with low thermal mass gas chromatography.

PubMed

Fitz, Brian D; Mannion, Brandyn C; To, Khang; Hoac, Trinh; Synovec, Robert E

2015-05-01

Low thermal mass gas chromatography (LTM-GC) was evaluated for rapid, high peak capacity separations with three injection methods: liquid, headspace solid phase micro-extraction (HS-SPME), and direct vapor. An Agilent LTM equipped with a short microbore capillary column was operated at a column heating rate of 250 °C/min to produce a 60s separation. Two sets of experiments were conducted in parallel to characterize the instrumental platform. First, the three injection methods were performed in conjunction with in-house built high-speed cryo-focusing injection (HSCFI) to cryogenically trap and re-inject the analytes onto the LTM-GC column in a narrower band. Next, the three injection methods were performed natively with LTM-GC. Using HSCFI, the peak capacity of a separation of 50 nl of a 73 component liquid test mixture was 270, which was 23% higher than without HSCFI. Similar peak capacity gains were obtained when using the HSCFI with HS-SPME (25%), and even greater with vapor injection (56%). For the 100 μl vapor sample injected without HSCFI, the preconcentration factor, defined as the ratio of the maximum concentration of the detected analyte peak relative to the analyte concentration injected with the syringe, was determined to be 11 for the earliest eluting peak (most volatile analyte). In contrast, the preconcentration factor for the earliest eluting peak using HSCFI was 103. Therefore, LTM-GC is demonstrated to natively provide in situ analyte trapping, although not to as great an extent as with HSCFI. We also report the use of LTM-GC applied with time-of-flight mass spectrometry (TOFMS) detection for rapid, high peak capacity separations from SPME sampled banana peel headspace. Copyright © 2015 Elsevier B.V. All rights reserved.

Separation and screening of short-chain chlorinated paraffins in environmental samples using comprehensive two-dimensional gas chromatography with micro electron capture detection.

PubMed

Xia, Dan; Gao, Lirong; Zhu, Shuai; Zheng, Minghui

2014-11-01

Short-chain chlorinated paraffins (SCCPs) are highly complex technical mixtures with thousands of isomers and numerous homologs. They are classified as priority candidate persistent organic pollutants under the Stockholm Convention for their persistence, bioaccumulation, and toxicity. Analyzing SCCPs is challenging because of the complexity of the mixtures. Chromatograms of SCCPs acquired using one-dimensional (1D) gas chromatography (GC) contain a large characteristic "peak" with a broad and unresolved profile. Comprehensive two-dimensional GC (GC×GC) shows excellent potential for separating complex mixtures. In this study, GC×GC coupled with micro electron capture detection (μECD) was used to separate and screen SCCPs. The chromatographic parameters, including the GC column types, oven temperature program, and modulation period, were systematically optimized. The SCCP congeners were separated into groups using a DM-1 column connected to a BPX-50 column. The SCCP congeners in technical mixtures were separated according to the number of chlorine substituents for a given carbon chain length and according to the number of carbon atoms plus chlorine atoms for different carbon chain lengths. A fish tissue sample was analyzed to illustrate the feasibility of the GC×GC-μECD method in analyzing biological samples. Over 1,500 compounds were identified in the fish extract, significantly more than were identified using 1D GC. The detection limits for five selected SCCP congeners were between 1 and 5 pg/L using the GC×GC method, and these were significantly lower than those achieved using 1D GC. This method is a good choice for analysis of SCCPs in environmental samples, exhibiting good separation and good sensitivity.

1.9 μm superficially porous packing material with radially oriented pores and tailored pore size for ultra-fast separation of small molecules and biomolecules.

PubMed

Min, Yi; Jiang, Bo; Wu, Ci; Xia, Simin; Zhang, Xiaodan; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2014-08-22

In this work, 1.9 μm reversed-phase packing materials with superficially porous structure were prepared to achieve the rapid and high efficient separation of peptides and proteins. The silica particles were synthesized via three steps, nonporous silica particle preparation by a modified seeded growth method, mesoporous shell formation by a one pot templated dissolution and redeposition strategy, and pore size expansion via acid-refluxing. By such a method, 1.9 μm superficially porous materials with 0.18 μm shell thickness and tailored pore diameter (10 nm, 15 nm) were obtained. After pore enlargement, the formerly dense arrays of mesoporous structure changed, the radially oriented pores dominated the superficially porous structure. The chromatographic performance of such particles was investigated after C18 derivatization. For packing materials with 1.9 μm diameter and 10 nm pore size, the column efficiency could reach 211,300 plates per m for naphthalene. To achieve the high resolution separation of peptides and proteins, particles with pore diameter of 15 nm were tailored, by which the baseline separation of 5 peptides and 5 intact proteins could be respectively achieved within 1 min, demonstrating the superiority in the high efficiency and high throughput analysis of biomolecules. Furthermore, BSA digests were well separated with peak capacity of 120 in 30 min on a 15 cm-long column. Finally, we compared our columns with a 1.7 μm Kinetex C18 column under the same conditions, our particles with 10nm pore size demonstrated similar performance for separation of the large intact proteins. Moreover, the particles with 15 nm pore size showed more symmetrical peaks for the separation of large proteins (BSA, OVA and IgG) and provided rapid separation of protein extracts from Escherichia coli in 5 min. All these results indicated that the synthesized 1.9 μm superficially porous silica packing materials would be promising in the ultra-fast and high-resolution separation of biomolecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Rapid and sensitive analytical method for monitoring of 12 organotin compounds in natural waters.

PubMed

Vahčič, Mitja; Milačič, Radmila; Sčančar, Janez

2011-03-01

A rapid analytical method for the simultaneous determination of 12 different organotin compounds (OTC): methyl-, butyl-, phenyl- and octyl-tins in natural water samples was developed. It comprises of in situ derivatisation (by using NaBEt4) of OTC in salty or fresh water sample matrix adjusted to pH 6 with Tris-citrate buffer, extraction of ethylated OTC into hexane, separation of OTC in organic phase on 15 m GC column and subsequent quantitative determination of separated OTC by ICP-MS. To optimise the pH of ethylation, phosphate, carbonate and Tris-citrate buffer were investigated alternatively to commonly applied sodium acetate - acetic acid buffer. The ethylation yields in Tris-citrate buffer were found to be better for TBT, MOcT and DOcT in comparison to commonly used acetate buffer. Iso-octane and hexane were examined as organic phase for extraction of ethylated OTC. The advantage of hexane was in its ability for quantitative determination of TMeT. GC column of 15 m in length was used for separation of studied OTC under the optimised separation conditions and its performances compared to 30 m column. The analytical method developed enables sensitive simultaneous determination of 12 different OTC and appreciably shortened analysis time in larger series of water samples. LOD's obtained for the newly developed method ranged from 0.05-0.06 ng Sn L-1 for methyl-, 0.11-0.45 ng Sn L-1 for butyl-, 0.11-0.16 ng Sn L-1 for phenyl-, and 0.07-0.10 ng Sn L-1 for octyl-tins. By applying the developed analytical method, marine water samples from the Northern Adriatic Sea containing mainly butyl- and methyl-tin species were analysed to confirm the proposed method's applicability.

Conventional and narrow bore short capillary columns with cyclodextrin derivatives as chiral selectors to speed-up enantioselective gas chromatography and enantioselective gas chromatography-mass spectrometry analyses.

PubMed

Bicchi, Carlo; Liberto, Erica; Cagliero, Cecilia; Cordero, Chiara; Sgorbini, Barbara; Rubiolo, Patrizia

2008-11-28

The analysis of complex real-world samples of vegetable origin requires rapid and accurate routine methods, enabling laboratories to increase sample throughput and productivity while reducing analysis costs. This study examines shortening enantioselective-GC (ES-GC) analysis time following the approaches used in fast GC. ES-GC separations are due to a weak enantiomer-CD host-guest interaction and the separation is thermodynamically driven and strongly influenced by temperature. As a consequence, fast temperature rates can interfere with enantiomeric discrimination; thus the use of short and/or narrow bore columns is a possible approach to speeding-up ES-GC analyses. The performance of ES-GC with a conventional inner diameter (I.D.) column (25 m length x 0.25 mm I.D., 0.15 microm and 0.25 microm d(f)) coated with 30% of 2,3-di-O-ethyl-6-O-tert-butyldimethylsilyl-beta-cyclodextrin in PS-086 is compared to those of conventional I.D. short column (5m length x 0.25 mm I.D., 0.15 microm d(f)) and of different length narrow bore columns (1, 2, 5 and 10 m long x 0.10 mm I.D., 0.10 microm d(f)) in analysing racemate standards of pesticides and in the flavour and fragrance field and real-world-samples. Short conventional I.D. columns gave shorter analysis time and comparable or lower resolutions with the racemate standards, depending mainly on analyte volatility. Narrow-bore columns were tested under different analysis conditions; they provided shorter analysis time and resolutions comparable to those of conventional I.D. ES columns. The narrow-bore columns offering the most effective compromise between separation efficiency and analysis time are the 5 and 2m columns; in combination with mass spectrometry as detector, applied to lavender and bergamot essential oil analyses, these reduced analysis time by a factor of at least three while separation of chiral markers remained unaltered.

[Preparation and performance characterization of gold nanoparticles modified chiral capillary electrochromatography stationary phase].

PubMed

Xiong, Lele; Li, Ruijun; Ji, Yibing

2017-07-08

Gold nanoparticles (GNPs, 15 nm) were prepared and introduced to amino groups derived silica monolithic column. Bovine serum albumin (BSA) was immobilized via covalent modification method onto the carboxylic functionalized GNPs to afford chiral stationary phase (CSP) for enantioseparation. GNPs were well dispersed and successfully incorporated onto the columns with the contents as high as 17.18% by characterization method such as transmission electron microscopy (TEM), ultraviolet (UV)-visible absorption spectra and scanning electron microscopy (SEM). The preparation conditions of the BSA modified CSP were optimized and 10% (v/v) 3-aminopropyltriethoxysilane (APTES) and 15 g/L BSA were selected as appropriate reaction conditions. The enantioseparation performance of the BSA modified CSP has been investigated by capillary electrochromatography (CEC). Enantiomers of tryptophan, ephedrine and atenolol were resolved, and the baseline separation of tryptophan was achieved. Meanwhile, the influences of pH value, buffer concentrations and applied voltages used on the chiral separation were studied, and the optimal separation conditions were 10 mmol/L phosphate buffer at pH 7.4 and 15 kV applied voltages. In comparison with the BSA modified CSP prepared by physical adsorption, the CSP prepared by covalent modification method had better separation results, and the analytes could be separated directly without pre-column derivatization. In addition, the prepared BSA modified CSP exhibited good run to run repeatability with relative standard deviations (RSDs) of the migration times and selectivity factors not more than 2.3% and 0.96%, respectively. This work offers a good thinking for modification with other proteins or other types of chiral selectors.

Single column comprehensive analysis of pharmaceutical preparations using dual-injection mixed-mode (ion-exchange and reversed-phase) and hydrophilic interaction liquid chromatography.

PubMed

Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett

2013-12-01

The comprehensive separation and detection of hydrophobic and hydrophilic active pharmaceutical ingredients (APIs), their counter-ions (organic, inorganic) and excipients, using a single mixed-mode chromatographic column, and a dual injection approach is presented. Using a mixed-mode Thermo Fisher Acclaim Trinity P1 column, APIs, their counter-ions and possible degradants were first separated using a combination of anion-exchange, cation-exchange and hydrophobic interactions, using a mobile phase consisting of a dual organic modifier/salt concentration gradient. A complementary method was also developed using the same column for the separation of hydrophilic bulk excipients, using hydrophilic interaction liquid chromatography (HILIC) under high organic solvent mobile phase conditions. These two methods were then combined within a single gradient run using dual sample injection, with the first injection at the start of the applied gradient (mixed-mode retention of solutes), followed by a second sample injection at the end of the gradient (HILIC retention of solutes). Detection using both ultraviolet absorbance and refractive index enabled the sensitive detection of APIs and UV-absorbing counter-ions, together with quantitative determination of bulk excipients. The developed approach was applied successfully to the analysis of a dry powder inhalers (Flixotide(®), Spiriva(®)), enabling comprehensive quantification of all APIs and excipients in the sample. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of pesticide residues in food with a 6% cyanopropylphenyl capillary column.

PubMed

Daft, J L

1989-02-01

A small-diameter 6% cyanopropylphenyl column is studied for its suitability for determining pesticides in food. Repeatability and linearity are satisfactory, and the column is capable of separating residue combinations that are known not to separate on methyl silicone columns. At 150 degrees C or 130 degrees C, the column satisfactorily separates five by-products of tecnazene, a growth regulator and sprout suppressant found in potatoes, and four by-products of quintozene, a soil and seed fungicide found in peanut products.

Preparation of quaternary amine monolithic column for strong anion-exchange chromatography and its application to the separation of Enterovirus 71.

PubMed

Gu, Huimin; Yin, Dezhong; Ren, Jie; Zhang, Baoliang; Zhang, Qiuyu

2016-10-15

Large size virion is unable to diffuse into pores of conventional porous chromatography particles. Therefore, separation of virion by conventional column-packing materials is not quite efficient. To solve this problem, a monolithic column with large convective pores and quaternary amine groups was prepared and was applied to separate Enterovirus 71 (EV71, ≈5700-6000kDa). Cross-section, pore structure, hydrodynamic performance, adsorption property and dynamic binding capacity of prepared monolithic column were determined. Double-pore structures, macropore at 2472nm and mesopore at 5-60nm, were formed. The porosity was up to 63.3%, which enable higher permeability and lower back pressure of the monolithic column than commercial UNO™ Q1 column. Based on the breakthrough curves, the loading capacity of bovine serum albumin was calculated to be 42.0mg per column. In addition, prepared quaternary amine monolithic column was proved to be suitable for the separation of protein mixture by strong anion-exchange chromatography. As a practical application, prepared monolith column presents excellent performance to the separation of EV71 from virus-proteins mixture. Copyright © 2016 Elsevier B.V. All rights reserved.

Unexpected retention behavior of baicalin: Hydrophilic interaction like properties of a reversed-phase column.

PubMed

Magda, Balázs; Márta, Zoltán; Imre, Tímea; Kalapos-Kovács, Bernadett; Klebovich, Imre; Fekete, Jenő; Szabó, Pál T

2015-01-01

The original aim of this study was to develop a method for the determination of baicalin from membrane vesicles. The unconventional chromatographic separation ("inverse gradient elution" on a reversed phase column) was due to a lucky chance, which is detailed and discussed in this study. The validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is proved to be sensitive, rapid and selective. Chromatographic separation was performed on a Zorbax SB-C8 column (250 mm × 4.6 mm, i.d.; 5 μm) with 0.1% formic acid in water and methanol by linear gradient elution. Quantification of baicalin was determined by multiple reaction monitoring (MRM) mode using electrospray ionization (ESI). The calibration curve was linear (r = 0.9987) over the concentration range from 1 to 1000 nM. The coefficient of variation and relative error of baicalin for intra- and inter-assay at three quality control (QC) levels were 2.0-10.2% and -6.1 to 6.7%, respectively. The lower limit of quantification (LLOQ) for baicalin was 1 nM (0.446 ng/ml), without preconcentration of the sample. This method was subsequently applied to vesicular transport assays of baicalin in membrane vesicles successfully. The developed method can open up new area of research in the chromatographic separation of flavonoids and their glucuronides. Copyright © 2015. Published by Elsevier B.V.

Apparatus and process for separating hydrogen isotopes

DOEpatents

Heung, Leung K; Sessions, Henry T; Xiao, Xin

2013-06-25

The apparatus and process for separating hydrogen isotopes is provided using dual columns, each column having an opposite hydrogen isotopic effect such that when a hydrogen isotope mixture feedstock is cycled between the two respective columns, two different hydrogen isotopes are separated from the feedstock.

Towards a method of rapid extraction of strontium-90 from urine: urine pretreatment and alkali metal removal

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

Hawkins, C.; Dietz, M.; Kaminski, M.

2016-03-01

A technical program to support the Centers of Disease Control and Prevention is being developed to provide an analytical method for rapid extraction of Sr-90 from urine, with the intent of assessing the general population’s exposure during an emergency response to a radiological terrorist event. Results are presented on the progress in urine sample preparation and chemical separation steps that provide an accurate and quantitative detection of Sr-90 based upon an automated column separation sequence and a liquid scintillation assay. Batch extractions were used to evaluate the urine pretreatment and the column separation efficiency and loading capacity based upon commercial,more » extractant-loaded resins. An efficient pretreatment process for decolorizing and removing organics from urine without measurable loss of radiostrontium from the sample was demonstrated. In addition, the Diphonix® resin shows promise for the removal of high concentrations of common strontium interferents in urine as a first separation step for Sr-90 analysis.« less

Fast gradient separation by very high pressure liquid chromatography: reproducibility of analytical data and influence of delay between successive runs.

PubMed

Stankovicha, Joseph J; Gritti, Fabrice; Beaver, Lois Ann; Stevensona, Paul G; Guiochon, Georges

2013-11-29

Five methods were used to implement fast gradient separations: constant flow rate, constant column-wall temperature, constant inlet pressure at moderate and high pressures (controlled by a pressure controller),and programmed flow constant pressure. For programmed flow constant pressure, the flow rates and gradient compositions are controlled using input into the method instead of the pressure controller. Minor fluctuations in the inlet pressure do not affect the mobile phase flow rate in programmed flow. There producibilities of the retention times, the response factors, and the eluted band width of six successive separations of the same sample (9 components) were measured with different equilibration times between 0 and 15 min. The influence of the length of the equilibration time on these reproducibilities is discussed. The results show that the average column temperature may increase from one separation to the next and that this contributes to fluctuation of the results.

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

PubMed

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

2014-08-01

Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual sample injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/sample was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

LC-method development for the quantification of neuromedin-like peptides. Emphasis on column choice and mobile phase composition.

PubMed

Van Wanseele, Yannick; Viaene, Johan; Van den Borre, Leslie; Dewachter, Kathleen; Vander Heyden, Yvan; Smolders, Ilse; Van Eeckhaut, Ann

2017-04-15

In this study, the separation of four neuromedin-like peptides is investigated on four different core-shell stationary phases. Moreover, the effect of the mobile phase composition, i.e. organic modifier (acetonitrile and methanol) and additive (trifluoroacetic acid, formic acid, acetic acid, ammonium formate and ammonium acetate) on the chromatographic performance is studied. An improvement in chromatographic performance is observed when using the ammonium salt instead of its corresponding acid as additive, except for the column containing a positively charged surface (C18+). In general, the RP-Amide column provided the highest separation power with different mobile phases. However, for the neuromedin-like peptides of interest, the C18+ column in combination with a mobile phase containing methanol as organic modifier and acetic acid as additive provided narrower and higher peaks. A three-factor, three-level design is applied to further optimize the method in terms of increased peak height and reduced solvent consumption, without loss in resolution. The optimized method was subsequently used to assess the in vitro microdialysis recovery of the peptides of interest. Recovery values between 4 and 8% were obtained using a perfusion flow rate of 2μL/min. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimization and validation of the reversed-phase high-performance liquid chromatography with fluorescence detection method for the separation of tocopherol and tocotrienol isomers in cereals, employing a novel sorbent material.

PubMed

Irakli, Maria N; Samanidou, Victoria F; Papadoyannis, Ioannis N

2012-03-07

The separation and determination of tocopherols (Ts) and tocotrienols (T3s) by reversed-phase high-performance liquid chromatography with fluorescence detection has been developed and validated after optimization of various chromatographic conditions and other experimental parameters. Analytes were separated on a PerfectSil Target ODS-3 (250 × 4.6 mm, 3 μm) column filled with a novel sorbent material of ultrapure silica gel. The separation of Ts and T3s was optimized in terms of mobile-phase composition and column temperature on the basis of the best compromise among efficiency, resolution, and analysis time. Using a gradient elution of mobile phase composed of isopropanol/water and 7 °C column temperature, a satisfactory resolution was achieved within 62 min. For the quantitative determination, α-T acetate (50 μg/mL) was used as the internal standard. Detection limits ranged from 0.27 μg/mL (γ-T) to 0.76 μg/mL (γ-T3). The validation of the method was examined performing intraday (n = 5) and interday (n = 3) assays and was found to be satisfactory, with high accuracy and precision results. Solid-phase extraction provided high relative extraction recoveries from cereal samples: 87.0% for γ-T3 and 115.5% for δ-T. The method was successfully applied to cereals, such as durum wheat, bread wheat, rice, barley, oat, rye, and corn.

Rapid and Green Separation of Mono- and Diesters of Monochloropropanediols by Ultrahigh Performance Supercritical Fluid Chromatography-Mass Spectrometry Using Neat Carbon Dioxide as a Mobile Phase.

PubMed

Jumaah, Firas; Jędrkiewicz, Renata; Gromadzka, Justyna; Namieśnik, Jacek; Essén, Sofia; Turner, Charlotta; Sandahl, Margareta

2017-09-20

This study demonstrates the effect of column selectivity and density of supercritical carbon dioxide (SC-CO 2 ) on the separation of monochloropropanediol (MCPD) esters, known as food toxicants, using SC-CO 2 without addition of cosolvent in ultrahigh performance supercritical fluid chromatography-mass spectrometry (UHPSFC-MS). This study shows that over 20 2-monochloropropanediol (2-MCPD) and 3-monochloropropanediol (3-MCPD) mono- and diesters are separated on a 2-picolylamine column in less than 12 min. The presence and position of a hydroxyl group in the structure, the number of unsaturated bonds, and the acyl chain length play a significant role in the separation of MCPD esters. The flow rate, backpressure, and column oven temperature, which affect the density of the mobile phase, were shown to have a substantial impact on retention, efficiency, and selectivity. The developed method was successfully applied for the determination of MCPD esters in refined oils and showed a close to excellent green analysis score using the Analytical Eco-Scale.

Liquid chromatographic separation and thermodynamic investigation of lorcaserin hydrochloride enantiomers on immobilized amylose-based chiral stationary phase.

PubMed

Wani, Dattatraya V; Rane, Vipul P; Mokale, Santosh N

2018-03-01

A novel liquid chromatographic method was developed for enantiomeric separation of lorcaserin hydrochloride on Chiralpak IA column containing chiral stationary phase immobilized with amylose tris (3.5-dimethylphenylcarbamate) as chiral selector. Baseline separation with resolution greater than 4 was achieved using mobile phase containing mixture of n-hexane/ethanol/methanol/diethylamine (95:2.5:2.5:0.1, v/v/v/v) at a flow rate of 1.2 mL/min. The limit of detection and limit of quantification of the S-enantiomer were found to be 0.45 and 1.5 μg/mL, respectively; the developed method was validated as per ICH guideline. The influence of column oven temperatures studied in the range of 20°C to 50°C on separation was studied; from this, retention, separation, and resolution were investigated. The thermodynamic parameters ΔH°, ΔS°, and ΔG° were evaluated from van't Hoff plots,(Ink' versus 1/T) and used to explain the strength of interaction between enantiomers and immobilized amylose-based chiral stationary phase. © 2017 Wiley Periodicals, Inc.

Determination of traces of 237Np in environmental samples by ICP-MS after separation using TOA extraction chromatography.

PubMed

Ji, Y Q; Li, J Y; Luo, S G; Wu, T; Liu, J L

2001-09-01

A simple, rapid, cost-efficient, and robust method for separation of 237Np with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analysis. The column efficiently retained 237Np in 2 mol L(-1) HNO3 medium and all of the 237Np was easily eluted with 0.02 mol L(-1) oxalic acid in 0.16 mol L(-1) HNO3 at 95 degrees C. The separated solutions were free from most matrix elements and were aspirated into the ICP-MS directly. The decontamination factor for 238U is more than 10(4). The instrumental detection limit for 237Np was 0.46 pg mL(-1), which corresponds to 1.2 x 10(-5) Bq mL(-1). The method is more rapid than traditional radiometric techniques. It is also considered to be more suitable for environmental monitoring than existing methods based on TOA.

ZIRCONIUM PHOSPHATE ADSORPTION METHOD

DOEpatents

Russell, E.R.; Adamson, A.S.; Schubert, J.; Boyd, G.E.

1958-11-01

A method is presented for separating plutonium values from fission product values in aqueous acidic solution. This is accomplished by flowing the solutlon containing such values through a bed of zirconium orthophosphate. Any fission products adsorbed can subsequently be eluted by washing the column with a solution of 2N HNO/sub 3/ and O.lN H/sub 3/PO/sub 4/. Plutonium values may subsequently be desorbed by contacting the column with a solution of 7N HNO/sub 3/ .

Fabrication and characterization of microelectromechanical systems-based gas chromatography column with embedded micro-posts for separation of environmental carcinogens.

PubMed

Sun, Jianhai; Cui, Dafu; Chen, Xing; Zhang, Lulu; Cai, Haoyuan; Li, Hui

2013-05-24

In this paper, a micro gas chromatography (μGC) column with embedded micro-posts was developed for increasing overall surface area of the columns which is able to support more of the stationary phase and reducing the effective width of the column, leading to higher separation efficiency. The proposed columns have a higher sample capacity as the overall surface area is about 3 times larger than that of open columns with the same dimensions. In order to achieve an even flow velocity in the channels, the location of the micro-posts in the linear channels and the configuration of curved channels were optimized by numerical simulation. The results have indicated that the proposed column separated 5 environmental carcinogens in less than 50s, achieved a separation efficiency of about 9500plates/m and eluted highly symmetrical Gaussian peaks. Copyright © 2013 Elsevier B.V. All rights reserved.

Recent advances in monolithic columns for protein and peptide separation by capillary liquid chromatography.

PubMed

Liang, Yu; Zhang, Lihua; Zhang, Yukui

2013-03-01

Capillary liquid chromatography (cLC) has great potential for protein and peptide separation, with advantages of high efficiency, high resolution, low sample consumption, and high sensitivity when coupled with mass spectrometry. In recent years, monoliths have been widely used as the stationary phases for capillary columns, owing to easy preparation, high permeability, fast mass transfer, and low backpressure. This review summarizes recent advances (2007-2012) in monolithic columns for protein and peptide separation by cLC. After a brief introduction on the preparation of monolithic capillary columns, the emphasis of this review is focused on the recent application of such columns for protein and peptide separation by cLC. Furthermore, the challenges and potential hot points of monolithic capillary columns in the future are discussed.

Methods of separating short half-life radionuclides from a mixture of radionuclides

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

Bray, L.A.; Ryan, J.L.

1998-09-15

The present invention is a method of obtaining a radionuclide product selected from the group consisting of {sup 223}Ra and {sup 225}Ac, from a radionuclide ``cow`` of {sup 227}Ac or {sup 229}Th respectively. The method comprises the steps of (a) permitting ingrowth of at least one radionuclide daughter from said radionuclide ``cow`` forming an ingrown mixture; (b) insuring that the ingrown mixture is a nitric acid ingrown mixture; (c) passing the nitric acid ingrown mixture through a first nitrate form ion exchange column which permits separating the ``cow`` from at least one radionuclide daughter; (d) insuring that the at leastmore » one radionuclide daughter contains the radionuclide product; (e) passing the at least one radionuclide daughter through a second ion exchange column and separating the at least one radionuclide daughter from the radionuclide product and (f) recycling the at least one radionuclide daughter by adding it to the ``cow``. In one embodiment the radionuclide ``cow`` is the {sup 227}Ac, the at least one daughter radionuclide is a {sup 227}Th and the product radionuclide is the {sup 223}Ra and the first nitrate form ion exchange column passes the {sup 227}Ac and retains the {sup 227}Th. In another embodiment the radionuclide ``cow`` is the {sup 229}Th, the at least one daughter radionuclide is a {sup 225}Ra and said product radionuclide is the {sup 225}Ac and the {sup 225}Ac and nitrate form ion exchange column retains the {sup 229}Th and passes the {sup 225}Ra/Ac. 8 figs.« less

Methods of separating short half-life radionuclides from a mixture of radionuclides

DOEpatents

Bray, Lane A.; Ryan, Jack L.

1998-01-01

The present invention is a method of obtaining a radionuclide product selected from the group consisting of .sup.223 Ra and .sup.225 Ac, from a radionuclide "cow" of .sup.227 Ac or .sup.229 Th respectively. The method comprises the steps of a) permitting ingrowth of at least one radionuclide daughter from said radionuclide "cow" forming an ingrown mixture; b) insuring that the ingrown mixture is a nitric acid ingrown mixture; c) passing the nitric acid ingrown mixture through a first nitrate form ion exchange column which permits separating the "cow" from at least one radionuclide daughter; d) insuring that the at least one radionuclide daughter contains the radionuclide product; e) passing the at least one radionuclide daughter through a second ion exchange column and separating the at least one radionuclide daughter from the radionuclide product and f) recycling the at least one radionuclide daughter by adding it to the "cow". In one embodiment the radionuclide "cow" is the .sup.227 Ac, the at least one daughter radionuclide is a .sup.227 Th and the product radionuclide is the .sup.223 Ra and the first nitrate form ion exchange column passes the .sup.227 Ac and retains the .sup.227 Th. In another embodiment the radionuclide "cow"is the .sup.229 Th, the at least one daughter radionuclide is a .sup.225 Ra and said product radionuclide is the .sup.225 Ac and the .sup.225 Ac and nitrate form ion exchange column retains the .sup.229 Th and passes the .sup.225 Ra/Ac.

Methods of separating short half-life radionuclides from a mixture of radionuclides

DOEpatents

Bray, L.A.; Ryan, J.L.

1998-09-15

The present invention is a method of obtaining a radionuclide product selected from the group consisting of {sup 223}Ra and {sup 225}Ac, from a radionuclide ``cow`` of {sup 227}Ac or {sup 229}Th respectively. The method comprises the steps of (a) permitting ingrowth of at least one radionuclide daughter from said radionuclide ``cow`` forming an ingrown mixture; (b) insuring that the ingrown mixture is a nitric acid ingrown mixture; (c) passing the nitric acid ingrown mixture through a first nitrate form ion exchange column which permits separating the ``cow`` from at least one radionuclide daughter; (d) insuring that the at least one radionuclide daughter contains the radionuclide product; (e) passing the at least one radionuclide daughter through a second ion exchange column and separating the at least one radionuclide daughter from the radionuclide product and (f) recycling the at least one radionuclide daughter by adding it to the ``cow``. In one embodiment the radionuclide ``cow`` is the {sup 227}Ac, the at least one daughter radionuclide is a {sup 227}Th and the product radionuclide is the {sup 223}Ra and the first nitrate form ion exchange column passes the {sup 227}Ac and retains the {sup 227}Th. In another embodiment the radionuclide ``cow`` is the {sup 229}Th, the at least one daughter radionuclide is a {sup 225}Ra and said product radionuclide is the {sup 225}Ac and the {sup 225}Ac and nitrate form ion exchange column retains the {sup 229}Th and passes the {sup 225}Ra/Ac. 8 figs.

METHOD OF AND APPARATUS FOR WITHDRAWING LIGHT ISOTOPIC PRODUCT FROM A LIQUID THERMAL DIFFUSION PLANT

DOEpatents

Dole, M.

1959-09-22

An improved process and apparatus are described for removing enriched product from the columns of a thermal diffusion plant for separation of isotopes. In the removal cycle, light product at the top cf the diffusion columns is circulated through the column tops and a shipping cylinder connected thereto unttl the concertation of enriched product in the cylinder reaches the desired point. During the removal, circulation through the bottoms is blocked bv freezing. in the diffusion cycle, the bottom portion is unfrozen, fresh feed is distributed to the bottoms of the columns, ard heavy product is withdrawn from the bottoms, while the tops of the columns are blocked by freezing.

Separation and purification of astaxanthin from Phaffia rhodozyma by preparative high-speed counter-current chromatography.

PubMed

Du, Xiping; Dong, Congcong; Wang, Kai; Jiang, Zedong; Chen, Yanhong; Yang, Yuanfan; Chen, Feng; Ni, Hui

2016-09-01

An effective high-speed counter-current chromatography (HSCCC) method was established for the preparative isolation and purification of astaxanthin from Phaffia rhodozyma. With a two-phase solvent system composed of n-hexane-acetone-ethanol-water (1:1:1:1, v/v/v/v), 100mg crude extract of P. rhodozyma was separated to yield 20.6mg of astaxanthin at 92.0% purity. By further one step silica gel column chromatography, the purity reached 99.0%. The chemical structure of astaxanthin was confirmed by thin layer chromatography (TLC), UV spectroscopy scanning, high performance liquid chromatography with a ZORBAX SB-C18 column and a Waters Nova-pak C18 column, and ESI/MS/MS. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrafast UPLC-ESI-MS and HPLC with monolithic column for determination of principal flavor compounds in vanilla pods.

PubMed

Sharma, Upendra K; Sharma, Nandini; Sinha, Arun K; Kumar, Neeraj; Gupta, Ajai P

2009-10-01

In this study, two novel chromatographic methods based on monolithic column high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) were developed for the ultrafast determination of principal flavor compounds namely vanillin, vanillic acid, p-hydroxybenzoic acid, and p-hydroxybenzaldehyde in ethanolic extracts of Vanilla planifolia pods. Good separation was achieved within 2.5 min using Chromolith RP18e column (100 mm x 4.6 mm) for HPLC and Acquity BEH C-18 (100 mm x 2.1 mm, 1.7 microm) column for UPLC. Both methods were compared in terms of total analysis time, mobile phase consumption, sensitivity, and validation parameters like precision, accuracy, LOD, and LOQ. Further, system suitability test data including resolution, capacity factor, theoretical plates, and tailing factor was determined for both the methods by ten replicate injections. Monolithic column based HPLC gave better results for most of the selected parameters while UPLC was found to be more eco-friendly with low mobile phase consumption and better sensitivity. Both methods may be used conveniently for the high throughput analysis of large number of samples in comparison to traditional particulate column.

Method of separating thorium from plutonium

DOEpatents

Clifton, David G.; Blum, Thomas W.

1984-01-01

A method of chemically separating plutonium from thorium. Plutonium and thorium to be separated are dissolved in an aqueous feed solution, preferably as the nitrate salts. The feed solution is acidified and sodium nitrite is added to the solution to adjust the valence of the plutonium to the +4 state. A chloride salt, preferably sodium chloride, is then added to the solution to induce formation of an anionic plutonium chloride complex. The anionic plutonium chloride complex and the thorium in solution are then separated by ion exchange on a strong base anion exchange column.

Method of separating thorium from plutonium

DOEpatents

Clifton, D.G.; Blum, T.W.

A method of chemically separating plutonium from thorium is claimed. Plutonium and thorium to be separated are dissolved in an aqueous feed solution, preferably as the nitrate salts. The feed solution is acidified and sodium nitrite is added to the solution to adjust the valence of the plutonium to the +4 state. A chloride salt, preferably sodium chloride, is then added to the solution to induce formation of an anionic plutonium chloride complex. The anionic plutonium chloride complex and the thorium in solution are then separated by ion exchange on a strong base anion exchange column.

Method of separating thorium from plutonium

DOEpatents

Clifton, D.G.; Blum, T.W.

1984-07-10

A method is described for chemically separating plutonium from thorium. Plutonium and thorium to be separated are dissolved in an aqueous feed solution, preferably as the nitrate salts. The feed solution is acidified and sodium nitrite is added to the solution to adjust the valence of the plutonium to the +4 state. A chloride salt, preferably sodium chloride, is then added to the solution to induce formation of an anionic plutonium chloride complex. The anionic plutonium chloride complex and the thorium in solution are then separated by ion exchange on a strong base anion exchange column.

Reversed Phase Column HPLC-ICP-MS Conditions for Arsenic Speciation Analysis of Rice Flour.

PubMed

Narukawa, Tomohiro; Matsumoto, Eri; Nishimura, Tsutomu; Hioki, Akiharu

2015-01-01

New measurement conditions for arsenic speciation analysis of rice flour were developed using HPLC-ICP-MS equipped with a reversed phase ODS column. Eight arsenic species, namely, arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA), arsenobetaine (AsB) and arsenocholine (AsC), were separated and determined under the proposed conditions. In particular, As(III) and MMAA and DMAA and AsB were completely separated using a newly proposed eluent containing ammonium dihydrogen phosphate. Importantly, the sensitivity changes, in particular those of As(V) and As(III) caused by coexisting elements and by complex matrix composition, which had been problematical in previously reported methods, were eliminated. The new eluent can be applied to C8, C18 and C30 ODS columns with the same effectiveness and with excellent repeatability. The proposed analytical method was successfully applied to extracts of rice flour certified reference materials.

[Determination of six main components in compound theophylline tablet by convolution curve method after prior separation by column partition chromatography

NASA Technical Reports Server (NTRS)

Zhang, S. Y.; Wang, G. F.; Wu, Y. T.; Baldwin, K. M. (Principal Investigator)

1993-01-01

On a partition chromatographic column in which the support is Kieselguhr and the stationary phase is sulfuric acid solution (2 mol/L), three components of compound theophylline tablet were simultaneously eluted by chloroform and three other components were simultaneously eluted by ammonia-saturated chloroform. The two mixtures were determined by computer-aided convolution curve method separately. The corresponding average recovery and relative standard deviation of the six components were as follows: 101.6, 1.46% for caffeine; 99.7, 0.10% for phenacetin; 100.9, 1.31% for phenobarbitone; 100.2, 0.81% for theophylline; 99.9, 0.81% for theobromine and 100.8, 0.48% for aminopyrine.

Apparatus and process for the separation of hydrophobic and hydrophilic particles using microbubble column flotation together with a process and apparatus for generation of microbubbles

DOEpatents

Yoon, Roe-Hoan; Adel, Gregory T.; Luttrell, Gerald H.

1992-01-01

A method and apparatus are disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal and minerals, so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators.

Apparatus and process for the separation of hydrophobic and hydrophilic particles using microbubble column flotation together with a process and apparatus for generation of microbubbles

DOEpatents

Yoon, Roe-Hoan; Adel, Gregory T.; Luttrell, Gerald H.

1998-01-01

A method and apparatus are disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal and minerals, so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators.

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

PubMed

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

2006-06-16

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

Two Synthetic Methods for Preparation of Chiral Stationary Phases Using Crystalline Degradation Products of Vancomycin: Column Performance for Enantioseparation of Acidic and Basic Drugs.

PubMed

Abdollahpour, Assem; Heydari, Rouhollah; Shamsipur, Mojtaba

2017-07-01

Two chiral stationary phases (CSPs) based on crystalline degradation products (CDPs) of vancomycin by using different synthetic methods were prepared and compared. Crystalline degradation products of vancomycin were produced by hydrolytic loss of ammonia from vancomycin molecules. Performances of two chiral columns prepared with these degradation products were investigated using several acidic and basic drugs as model analytes. Retention and resolution of these analytes on the prepared columns, as two main parameters, in enantioseparation were studied. The results demonstrated that the stationary phase preparation procedure has a significant effect on the column performance. The resolving powers of prepared columns for enantiomers resolution were changed with the variation in vancomycin-CDP coverage on the silica support. Elemental analysis was used to monitor the surface coverage of silica support by vancomycin-CDP. The results showed that both columns can be successfully applied to chiral separation studies.

Periodic imidazolium-bridged hybrid monolith for high-efficiency capillary liquid chromatography with enhanced selectivity.

PubMed

Qiao, Xiaoqiang; Zhang, Niu; Han, Manman; Li, Xueyun; Qin, Xinying; Shen, Shigang

2017-03-01

A novel periodic imidazolium-bridged hybrid monolithic column was developed. With diene imidazolium ionic liquid 1-allyl-3-vinylimidazolium bromide as both cross-linker and organic functionalized reagent, a new periodic imidazolium-bridged hybrid monolithic column was facilely prepared in capillary with homogeneously distributed cationic imidazolium by a one-step free-radical polymerization with polyhedral oligomeric silsesquioxane methacryl substituted. The successful preparation of the new column was verified by Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, and surface area analysis. Most interestingly, the bonded amount of 1-allyl-3-vinylimidazolium bromide of the new column is three times higher than that of the conventional imidazolium-embedded hybrid monolithic column and the specific surface area of the column reached 478 m 2 /g. The new column exhibited high stability, excellent separation efficiency, and enhanced separation selectivity. The column efficiency reached 151 000 plates/m for alkylbenzenes. Furthermore, the new column was successfully used for separation of highly polar nucleosides and nucleic acid bases with pure water as mobile phase and even bovine serum albumin tryptic digest. All these results demonstrate the periodic imidazolium-bridged hybrid monolithic column is a good separation media and can be used for chromatographic separation of small molecules and complex biological samples with high efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method and apparatus for continuous annular electrochromatography

DOEpatents

Scott, Charles D.

1987-01-01

Separation of complex mixtures and solutions can be carried out using a method and apparatus for continuous annular electrochromatography. Solutes are diverted radially by an imposed electrical field as they move downward in a rotating chromatographic column.

Spiral Countercurrent Chromatography

PubMed Central

Ito, Yoichiro; Knight, Martha; Finn, Thomas M.

2013-01-01

For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous–aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography. PMID:23833207

Two-dimensional preparative liquid chromatography system for preparative separation of minor amount components from complicated natural products.

PubMed

Qiu, Ying-Kun; Chen, Fang-Fang; Zhang, Ling-Ling; Yan, Xia; Chen, Lin; Fang, Mei-Juan; Wu, Zhen

2014-04-11

An on-line comprehensive two-dimensional preparative liquid chromatography system was developed for preparative separation of minor amount components from complicated natural products. Medium-pressure liquid chromatograph (MPLC) was applied as the first dimension and preparative HPLC as the second one, in conjunction with trapping column and makeup pump. The performance of the trapping column was evaluated, in terms of column size, dilution ratio and diameter-height ratio, as well as system pressure from the view of medium pressure liquid chromatograph. Satisfactory trapping efficiency can be achieved using a commercially available 15 mm × 30 mm i.d. ODS pre-column. The instrument operation and the performance of this MPLC×preparative HPLC system were illustrated by gram-scale isolation of crude macro-porous resin enriched water extract of Rheum hotaoense. Automated multi-step preparative separation of 25 compounds, whose structures were identified by MS, (1)H NMR and even by less-sensitive (13)C NMR, could be achieved in a short period of time using this system, exhibiting great advantages in analytical efficiency and sample treatment capacity compared with conventional methods. Copyright © 2014 Elsevier B.V. All rights reserved.

Development and optimisation of an HPLC-DAD-ESI-Q-ToF method for the determination of phenolic acids and derivatives.

PubMed

Restivo, Annalaura; Degano, Ilaria; Ribechini, Erika; Colombini, Maria Perla

2014-01-01

A method for the HPLC-MS/MS analysis of phenols, including phenolic acids and naphtoquinones, using an amide-embedded phase column was developed and compared to the literature methods based on classical C18 stationary phase columns. RP-Amide is a recently developed polar embedded stationary phase, whose wetting properties mean that up to 100% water can be used as an eluent. The increased retention and selectivity for polar compounds and the possibility of working in 100% water conditions make this column particularly interesting for the HPLC analysis of phenolic acids and derivatives. In this study, the chromatographic separation was optimised on an HPLC-DAD, and was used to separate 13 standard phenolic acids and derivatives. The method was validated on an HPLC-ESI-Q-ToF. The acquisition was performed in negative polarity and MS/MS target mode. Ionisation conditions and acquisition parameters for the Q-ToF detector were investigated by working on collision energies and fragmentor potentials. The performance of the method was fully evaluated on standards. Moreover, several raw materials containing phenols were analysed: walnut, gall, wine, malbec grape, French oak, red henna and propolis. Our method allowed us to characterize the phenolic composition in a wide range of matrices and to highlight possible matrix effects.

Critical assessment of three high performance liquid chromatography analytical methods for food carotenoid quantification.

PubMed

Dias, M Graça; Oliveira, Luísa; Camões, M Filomena G F C; Nunes, Baltazar; Versloot, Pieter; Hulshof, Paul J M

2010-05-21

Three sets of extraction/saponification/HPLC conditions for food carotenoid quantification were technically and economically compared. Samples were analysed for carotenoids alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, lycopene, and zeaxanthin. All methods demonstrated good performance in the analysis of a composite food standard reference material for the analytes they are applicable to. Methods using two serial connected C(18) columns and a mobile phase based on acetonitrile, achieved a better carotenoid separation than the method using a mobile phase based on methanol and one C(18)-column. Carotenoids from leafy green vegetable matrices appeared to be better extracted with a mixture of methanol and tetrahydrofuran than with tetrahydrofuran alone. Costs of carotenoid determination in foods were lower for the method with mobile phase based on methanol. However for some food matrices and in the case of E-Z isomer separations, this was not technically satisfactory. Food extraction with methanol and tetrahydrofuran with direct evaporation of these solvents, and saponification (when needed) using pyrogallol as antioxidant, combined with a HPLC system using a slight gradient mobile phase based on acetonitrile and a stationary phase composed by two serial connected C(18) columns was the most technically and economically favourable method. 2010. Published by Elsevier B.V.

Programmable selectivity for GC with series-coupled columns using pulsed heating of the second column.

PubMed

Whiting, Joshua; Sacks, Richard

2003-05-15

A series-coupled ensemble of a nonpolar dimethyl polysiloxane column and a polar trifluoropropylmethyl polysiloxane column with independent at-column heating is used to obtain pulsed heating of the second column. For mixture component bands that are separated by the first column but coelute from the column ensemble, a temperature pulse is initiated after the first of the two components has crossed the column junction point and is in the second column, while the other component is still in the first column. This accelerates the band for the first component. If the second column cools sufficiently prior to the second component band crossing the junction, the second band experiences less acceleration, and increased separation is observed for the corresponding peaks in the ensemble chromatogram. High-speed at-column heating is obtained by wrapping the fused-silica capillary column with resistance heater wire and sensor wire. Rapid heating for a temperature pulse is obtained with a short-duration linear heating ramp of 1000 degrees C/min. During a pulse, the second-column temperature increases by 20-100 degrees C in a few seconds. Using a cold gas environment, cooling to a quiescent temperature of 30 degrees C can be obtained in approximately 25 s. The effects of temperature pulse initiation time and amplitude on ensemble peak separation and resolution are described. A series of appropriately timed temperature pulses is used to separate three coeluting pairs of components in a 13-component mixture.

Development of gas chromatography-flame ionization detection system with a single column and liquid nitrogen-free for measuring atmospheric C2-C12 hydrocarbons.

PubMed

Liu, Chengtang; Mu, Yujing; Zhang, Chenglong; Zhang, Zhibo; Zhang, Yuanyuan; Liu, Junfeng; Sheng, Jiujiang; Quan, Jiannong

2016-01-04

A liquid nitrogen-free GC-FID system equipped with a single column has been developed for measuring atmospheric C2-C12 hydrocarbons. The system is consisted of a cooling unit, a sampling unit and a separation unit. The cooling unit is used to meet the temperature needs of the sampling unit and the separation unit. The sampling unit includes a dehydration tube and an enrichment tube. No breakthrough of the hydrocarbons was detected when the temperature of the enrichment tube was kept at -90 °C and sampling volume was 400 mL. The separation unit is a small round oven attached on the cooling column. A single capillary column (OV-1, 30 m × 0.32 mm I.D.) was used to separate the hydrocarbons. An optimal program temperature (-60 ∼ 170 °C) of the oven was achieved to efficiently separate C2-C12 hydrocarbons. There were good linear correlations (R(2)=0.993-0.999) between the signals of the hydrocarbons and the enrichment amount of hydrocarbons, and the relative standard deviation (RSD) was less than 5%, and the method detection limits (MDLs) for the hydrocarbons were in the range of 0.02-0.10 ppbv for sampling volume of 400 mL. Field measurements were also conducted and more than 50 hydrocarbons from C2 to C12 were detected in Beijing city. Copyright © 2015 Elsevier B.V. All rights reserved.

[Development of an automatic vacuum liquid chromatographic device and its application in the separation of the components from Schisandra chinensis (Turz) Baill].

PubMed

Zhu, Jingbo; Liu, Baoyue; Shan, Shibo; Ding, Yanl; Kou, Zinong; Xiao, Wei

2015-08-01

In order to meet the needs of efficient purification of products from natural resources, this paper developed an automatic vacuum liquid chromatographic device (AUTO-VLC) and applied it to the component separation of petroleum ether extracts of Schisandra chinensis (Turcz) Baill. The device was comprised of a solvent system, a 10-position distribution valve, a 3-position changes valve, dynamic axis compress chromatographic columns with three diameters, and a 10-position fraction valve. The programmable logic controller (PLC) S7- 200 was adopted to realize the automatic control and monitoring of the mobile phase changing, column selection, separation time setting and fraction collection. The separation results showed that six fractions (S1-S6) of different chemical components from 100 g Schisandra chinensis (Turcz) Baill. petroleum ether phase were obtained by the AUTO-VLC with 150 mm diameter dynamic axis compress chromatographic column. A new method used for the VLC separation parameters screened by using multiple development TLC was developed and confirmed. The initial mobile phase of AUTO-VLC was selected by taking Rf of all the target compounds ranging from 0 to 0.45 for fist development on the TLC; gradient elution ratio was selected according to k value (the slope of the linear function of Rf value and development times on the TLC) and the resolution of target compounds; elution times (n) were calculated by the formula n ≈ ΔRf/k. A total of four compounds with the purity more than 85% and 13 other components were separated from S5 under the selected conditions for only 17 h. Therefore, the development of the automatic VLC and its method are significant to the automatic and systematic separation of traditional Chinese medicines.

Multiple dual mode counter-current chromatography with variable duration of alternating phase elution steps.

PubMed

Kostanyan, Artak E; Erastov, Andrey A; Shishilov, Oleg N

2014-06-20

The multiple dual mode (MDM) counter-current chromatography separation processes consist of a succession of two isocratic counter-current steps and are characterized by the shuttle (forward and back) transport of the sample in chromatographic columns. In this paper, the improved MDM method based on variable duration of alternating phase elution steps has been developed and validated. The MDM separation processes with variable duration of phase elution steps are analyzed. Basing on the cell model, analytical solutions are developed for impulse and non-impulse sample loading at the beginning of the column. Using the analytical solutions, a calculation program is presented to facilitate the simulation of MDM with variable duration of phase elution steps, which can be used to select optimal process conditions for the separation of a given feed mixture. Two options of the MDM separation are analyzed: 1 - with one-step solute elution: the separation is conducted so, that the sample is transferred forward and back with upper and lower phases inside the column until the desired separation of the components is reached, and then each individual component elutes entirely within one step; 2 - with multi-step solute elution, when the fractions of individual components are collected in over several steps. It is demonstrated that proper selection of the duration of individual cycles (phase flow times) can greatly increase the separation efficiency of CCC columns. Experiments were carried out using model mixtures of compounds from the GUESSmix with solvent systems hexane/ethyl acetate/methanol/water. The experimental results are compared to the predictions of the theory. A good agreement between theory and experiment has been demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

Supramolecular separation mechanism of pentafluorophenyl column using ibuprofen and omeprazole as markers: LC-MS and simulation study.

PubMed

Hussain, Afzal; AlAjmi, Mohamed F; Ali, Imran

2018-06-01

The pentafluorophenyl (PFP) column is emerging as a new advancement in separation science to analyze a wide range of analytes and, thus, its separation mechanism at supramolecular level is significant. We developed a mechanism for the separation of ibuprofen and omeprazole using different combinations (ranging from 50:50 to 60:40) of water-acetonitrile containing 0.1% formic acid as the mobile phase. The column used was Waters Acquity UPLC HSS PFP (75 × 2.1 mm, 1.8 μm). The reverse order of elution was observed in different combinations of the mobile phases. The docking study indicated hydrogen bonding between ibuprofen and PFP stationary phase (binding energy was -11.30 kJ/mol). Separation at PFP stationary phase is controlled by hydrogen bonding along with π-π interactions. This stationary phase may be used to analyze both aromatic and aliphatic analytes. The developed mechanism will be useful to separate various analytes by considering the possible interactions, leading to saving of energy, time and money. In addition, this work will be highly useful in preparative chromatography where separation is the major problem at a large scale. Moreover, the developed LC-MS-QTOF method may be used to analyze ibuprofen and omeprazole in an unknown sample owing to the low value of detection limits. Copyright © 2018 John Wiley & Sons, Ltd.

The analysis of carbohydrates in milk powder by a new "heart-cutting" two-dimensional liquid chromatography method.

PubMed

Ma, Jing; Hou, Xiaofang; Zhang, Bing; Wang, Yunan; He, Langchong

2014-03-01

In this study, a new"heart-cutting" two-dimensional liquid chromatography method for the simultaneous determination of carbohydrate contents in milk powder was presented. In this two dimensional liquid chromatography system, a Venusil XBP-C4 analysis column was used in the first dimension ((1)D) as a pre-separation column, a ZORBAX carbohydrates analysis column was used in the second dimension ((2)D) as a final-analysis column. The whole process was completed in less than 35min without a particular sample preparation procedure. The capability of the new two dimensional HPLC method was demonstrated in the determination of carbohydrates in various brands of milk powder samples. A conventional one dimensional chromatography method was also proposed. The two proposed methods were both validated in terms of linearity, limits of detection, accuracy and precision. The comparison between the results obtained with the two methods showed that the new and completely automated two dimensional liquid chromatography method is more suitable for milk powder sample because of its online cleanup effect involved. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Process for the production of ultrahigh purity silane with recycle from separation columns

NASA Technical Reports Server (NTRS)

Coleman, Larry M. (Inventor)

1982-01-01

Tri- and dichlorosilanes formed by hydrogenation in the course of the reaction of metallurgical silicon, hydrogen and recycle silicon tetrachloride are employed as feed into a separation column arrangement of sequential separation columns and redistribution reactors which processes the feed into ultrahigh purity silane and recycle silicon tetrachloride. A slip stream is removed from the bottom of two sequential columns and added to the recycle silicon tetrachloride process stream causing impurities in the slip streams to be subjected to reactions in the hydrogenation step whereby waste materials can be formed and readily separated.

Process for the production of ultrahigh purity silane with recycle from separation columns

DOEpatents

Coleman, Larry M.

1982-07-20

Tri- and dichlorosilanes formed by hydrogenation in the course of the reaction of metallurgical silicon, hydrogen and recycle silicon tetrachloride are employed as feed into a separation column arrangement of sequential separation columns and redistribution reactors which processes the feed into ultrahigh purity silane and recycle silicon tetrachloride. A slip stream is removed from the bottom of two sequential columns and added to the recycle silicon tetrachloride process stream causing impurities in the slip streams to be subjected to reactions in the hydrogenation step whereby waste materials can be formed and readily separated.

Resolving the chemical heterogeneity of natural organic matter: new insights from comprehensive two-dimensional liquid chromatography.

PubMed

Duarte, Regina M B O; Barros, Ana C; Duarte, Armando C

2012-08-03

For the purpose of resolving the chemical heterogeneity of natural organic matter (NOM), comprehensive two-dimensional liquid chromatography (LC×LC) was employed for the first time to map the hydrophobicity versus molecular weight (MW) distribution of two well-known complex organic mixtures: Suwannee River Fulvic Acids (SR-FA) and Pony Lake Fulvic Acids (PL-FA). Two methods have been developed using either a conventional reversed-phase (RP) silica column or a mixed-mode hydrophilic interaction column operating under aqueous RP mode in the first dimension, and a size-exclusion column in the second dimension. The LC×LC fractions were screened on-line by UV at 254 nm, molecular fluorescence at excitation/emission wavelengths (λ(Exc)/λ(Em)) of 240/450 nm, and by evaporative light scattering. The MW distributions of these two NOM samples were further characterized by number (Mn) and weight (Mw) average MW, and by polydispersity (Mw/Mn). Findings suggest that the combination of two independent separation mechanisms is promising in extend the range of NOM separation. For the cases where NOM separation was accomplished, smaller Mw group fractions seem to be related to a more hydrophobic nature. Regardless of the detection method, the complete range of MW distribution provided by both comprehensive LC×LC methods was found to be lower than those reported in the literature. Copyright © 2012 Elsevier B.V. All rights reserved.

Thermal gravitational separation of ternary mixture n-dodecane/isobutylbenzene/tetralin components in a porous medium

NASA Astrophysics Data System (ADS)

Larabi, Mohamed Aziz; Mutschler, Dimitri; Mojtabi, Abdelkader

2016-06-01

Our present work focuses on the coupling between thermal diffusion and convection in order to improve the thermal gravitational separation of mixture components. The separation phenomenon was studied in a porous medium contained in vertical columns. We performed analytical and numerical simulations to corroborate the experimental measurements of the thermal diffusion coefficients of ternary mixture n-dodecane, isobutylbenzene, and tetralin obtained in microgravity in the international space station. Our approach corroborates the existing data published in the literature. The authors show that it is possible to quantify and to optimize the species separation for ternary mixtures. The authors checked, for ternary mixtures, the validity of the "forgotten effect hypothesis" established for binary mixtures by Furry, Jones, and Onsager. Two complete and different analytical resolution methods were used in order to describe the separation in terms of Lewis numbers, the separation ratios, the cross-diffusion coefficients, and the Rayleigh number. The analytical model is based on the parallel flow approximation. In order to validate this model, a numerical simulation was performed using the finite element method. From our new approach to vertical separation columns, new relations for mass fraction gradients and the optimal Rayleigh number for each component of the ternary mixture were obtained.

Separation and characterization of polycyclic aromatic hydrocarbons and alkylphenols in coal derived solvents

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

Hurtubise, R.J.; Allen, T.W.; Hussain, A.

1981-03-29

Dry-column chromatography with an aluminum oxide stationary phase and a n-hexane-ether (19:1) mobile phase was used to separate polycyclic aromatic hydrocarbons (PAH) by ring size. Prior to the dry-column chromatography step, the coal derived solvents were added to an acid treated silica gel column and eluted with chloroform. This step removed pyridine-type nitrogen heterocycles. After separation of the individual ring fractions, the fractions were further separated by either thin layer chromatography (TLC) or high performance liquid chromatography (HPLC). If TLC was used, then after separation fluorescence profiles of each PAH ring fraction distributed on 30%-acetylated cellulose chromatoplates were obtained withmore » a spectrodensitometer. Measurement of fluorescence peak heights gave an approximate measure of the amount of the 3-, 4-, 5-, and 6- ring PAH. For HPLC separation, the 3- and 4- ring PAH fractions obtained from the dry-column chromatography step were separated with a ..mu..-Bondapak C/sub 18/ column and methanol:water (65:35) mobile phase. The HPLC separated PAH were characterized by chromatographic correlation factors and corrected fluorescence excitation spectra. Alkylphenols were identified in coal recycle solvent sample following separation by HPLC.« less

Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide.

PubMed

Hayama, Tadashi; Katoh, Kenji; Aoki, Takayoshi; Itoyama, Miki; Todoroki, Kenichiro; Yoshida, Hideyuki; Yamaguchi, Masatoshi; Nohta, Hitoshi

2012-11-28

A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440-540 nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4-1.2 μg L(-1) and 1.4-3.9 μg L(-1), respectively. The method was validated at 0.1 and 1.0 μg L(-1) levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

HPLC separation of triacylglycerol positional isomers on a polymeric ODS column.

PubMed

Kuroda, Ikuma; Nagai, Toshiharu; Mizobe, Hoyo; Yoshimura, Nobuhito; Gotoh, Naohiro; Wada, Shun

2008-07-01

A polymeric ODS column was applied to the resolution of triacylglycerol positional isomers (TAG-PI), i.e. 1,3-dioleoyl-2-palmitoyl-glycerol (OPO) and 1,2-dioleoyl-3-palmitoyl-rac-glycerol (OOP), with a recycle HPLC system. To investigate the ODS column species and the column temperatures for the resolution of a TAG-PI pair, a mixture of OPO and OOP was subjected to an HPLC system equipped with a non-endcapped polymeric, endcapped monomeric, endcapped intermediate, or non-endcapped monomeric ODS column at three different column temperatures (40, 25, or 10 degrees C). Only the non-endcapped polymeric ODS column achieved the separation of OPO and OOP, and the lowest column temperature (10 degrees C) showed the best resolution for them. The other pair of TAG-PI, a mixture of 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO) was also subjected to the system equipped with a non-endcapped polymeric or monomeric ODS column at five different column temperatures (40, 32, 25, 17, and 10 degrees C). Thus, POP and PPO were also separated on only the non-endcapped polymeric ODS column at 25 degrees C. However, no clear peak appeared at 10 degrees C. These results would indicate that the polymeric ODS stationary phase has an ability to recognize the structural differences between TAG-PI pairs. Also, the column temperature is a very important factor for separating the TAG-PI pair, and the optimal temperature would relate to the solubility of TAG-PI in the mobile phase. Furthermore, the recycle HPLC system provided measurements for the separation and analysis of TAG-PI pairs.

Identification and anti-oxidant capacity determination of phenolics and their glycosides in elderflower by on-line HPLC-CUPRAC method.

PubMed

Çelik, S Esin; Özyürek, Mustafa; Güçlü, Kubilay; Çapanoğlu, Esra; Apak, Reşat

2014-01-01

Development and application of an on-line cupric reducing anti-oxidant capacity (CUPRAC) assay coupled with HPLC for separation and on-line determination of phenolic anti-oxidants in elderflower (Sambucus nigra L.) extracts for their anti-oxidant capacity are significant for evaluating health-beneficial effects. Moreover, this work aimed to assay certain flavonoid glycosides of elderflower that could not be identified/quantified by other similar on-line HPLC methods (i.e. 2,2-diphenyl-1-picrylhdrazyl and 2, 2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid). To identify anti-oxidant constituents in elderflower by HPLC and to evaluate their individual anti-oxidant capacities by on-line HPLC-CUPRAC assay with a post-column derivatisation system. The separation and UV detection of polyphenols were performed on a C18 -column using gradient elution with two different mobile phase solutions, that is acetonitrile and 1% glacial acetic acid, with detection at 340 nm. The HPLC-separated anti-oxidant polyphenols in column effluent react with copper(II)-neocuproine in a reaction-coil to reduce the latter to copper(I)-neocuproine (Cu(I)-Nc) chelate having maximum absorption at 450 nm. The detection limits of tested compounds at 450 nm after post-column derivatisation were compared with those of at 340 nm UV-detection without derivatisation. LOD values (µg/mL) of quercetin and its glycosides at 450 nm were lower than those of UV detection at 340 nm. This method was applied successfully to elderflower extract. The flavonol glycosides of quercetin and kaempferol bound to several sugar components (glucose, rhamnose, galactose and rutinose) were identified in the sample. The on-line HPLC-CUPRAC method was advantageous over on-line ABTS and DPPH methods for measuring the flavonoid glycosides of elderflower. Copyright © 2014 John Wiley & Sons, Ltd.

Quality by design: a systematic and rapid liquid chromatography and mass spectrometry method for eprosartan mesylate and its related impurities using a superficially porous particle column.

PubMed

Kalariya, Pradipbhai D; Kumar Talluri, Murali V N; Gaitonde, Vinay D; Devrukhakar, Prashant S; Srinivas, Ragampeta

2014-08-01

The present work describes the systematic development of a robust, precise, and rapid reversed-phase liquid chromatography method for the simultaneous determination of eprosartan mesylate and its six impurities using quality-by-design principles. The method was developed in two phases, screening and optimization. During the screening phase, the most suitable stationary phase, organic modifier, and pH were identified. The optimization was performed for secondary influential parameters--column temperature, gradient time, and flow rate using eight experiments--to examine multifactorial effects of parameters on the critical resolution and generated design space representing the robust region. A verification experiment was performed within the working design space and the model was found to be accurate. This study also describes other operating features of the column packed with superficially porous particles that allow very fast separations at pressures available in most liquid chromatography instruments. Successful chromatographic separation was achieved in less than 7 min using a fused-core C18 (100 mm × 2.1 mm, 2.6 μm) column with linear gradient elution of 10 mM ammonium formate (pH 3.0) and acetonitrile as the mobile phase. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance with the International Conference on Harmonization Q2 (R1) guidelines. The impurities were identified by liquid chromatography with mass spectrometry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of pterins in urine by HPLC with UV and fluorescent detection using different types of chromatographic stationary phases (HILIC, RP C8, RP C18).

PubMed

Kośliński, Piotr; Jarzemski, Piotr; Markuszewski, Michał J; Kaliszan, Roman

2014-03-01

Pterins are a class of potential cancer biomarkers. New methods involving hydrophilic interaction liquid chromatography (HILIC) and reversed phase (RP) high-performance liquid chromatography have been developed for analysis of eight pterin compounds: 6,7-dimethylpterin, pterin, 6-OH-methylpterin, biopterin, isoxanthopterin, neopterin, xanthopterin, and pterin-6-carboxylic acid. The effect of mobile phase composition, buffer type, pH and concentration on retention using HILIC, C8 and C18 RP stationary phases were examined. Separation of pterins on RP and HILIC stationary phase was performed and optimized. Eight pterins were successfully separated on HILIC Luna diol-bonded phases, Aquasil C18 RP column and LiChrospher C8 RP column. Determination and separation of the pterins from urine samples were performed on HILIC Luna and LiChrospher C8 RP columns which were chosen as the most appropriate ones. Finally, LiChrospher C8 RP column with fluorescence detection was selected for further validation of the method. The optimum chromatographic condition was mobile phase methanol (A)/phosphoric buffer pH 7, 10mM (B), isocratic elution 0-15min 5% A flow=0.5ml/min 15-17min. 5% A, flow=0.5-1ml/min the linearity (R(2)>0.997) and retention time repeatability (RSD%<1) were at satisfactory level. The precision of peak areas expressed as RSD in % was between 0.55 and 14. Pterins detection limits varied from 0.041ng/ml to 2.9ng/ml. Finally, HPLC method was used for the analysis of pterins in urine samples with two different oxidation procedures. Concentration levels of pterin compounds in bladder cancer patients and healthy subjects were compared. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparative chromatography of chloroplast pigment

NASA Technical Reports Server (NTRS)

Grandolfo, M.; Sherma, J.; Strain, H. H.

1969-01-01

Methods for isolation of low concentration pigments of the cocklebur species are described. The methods entail two step chromatography so that the different sorption properties of the various pigments in varying column parameters can be utilized. Columnar and thin layer methods are compared. Many conditions influence separability of the chloroplasts.

Linear solvation energy relationships in normal phase chromatography based on gradient separations.

PubMed

Wu, Di; Lucy, Charles A

2017-09-22

Coupling the modified Soczewiñski model and one gradient run, a gradient method was developed to build a linear solvation energy relationship (LSER) for normal phase chromatography. The gradient method was tested on dinitroanilinopropyl (DNAP) and silica columns with hexane/dichloromethane (DCM) mobile phases. LSER models built based on the gradient separation agree with those derived from a series of isocratic separations. Both models have similar LSER coefficients and comparable goodness of fit, but the LSER model based on gradient separation required fewer trial and error experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of intracellular UDP-sugars in hyaluronic acid-producing Streptococcus zooepidemicus.

PubMed

Franke, Lukáš; Čožíková, Dagmar; Smirnou, Dzianis; Hermannová, Martina; Hanová, Tereza; Růžičková, Andrea; Velebný, Vladimír

2015-08-01

Two chromatographic methods for the quantitative analysis of uridine diphosphate (UDP) sugars involved in hyaluronan pathway of Streptococcus zooepidemicus (SEZ) were developed and compared. The sample preparation protocol using centrifugation and extraction in hot ethanol was employed prior to the analyses. Separation was achieved using an anion exchange Spherisorb SAX column or a Shodex QA-825 column connected with a photodiode array (PDA) detector. To increase the throughput of the chromatography method employing the Spherisorb SAX column, the solid phase extraction (SPE) procedure was introduced. Method validation results displayed that limits of detection (LODs) of UDP-glucose (UDP-Glc), UDP-N-acetylglucosamine (UDP-GlcNAc) and UDP-glucuronic acid (UDP-GlcA) calculated according to QC Expert software were in the low micromolar range and the coefficient of correlation (R(2)) was above 0.997. However, the analytical technique using the Spherisorb SAX column resulted in 80-90% recoveries and low LODs (≤6.19μM), the Shodex QA-825 column showed better long-term stability and reproducible chromatographic properties (RSD≤5.60%). The Shodex QA-825 column was successfully used to monitor UDP-sugar levels during the growth rate of SEZ cells. Copyright © 2015 Elsevier B.V. All rights reserved.

C(18) columns for the simultaneous determination of oxytetracycline and its related substances by reversed-phase high performance liquid chromatography and UV detection.

PubMed

Smyrniotakis, C G; Archontaki, Helen A

2007-01-17

Simultaneous determination of oxytetracycline, 4-epioxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline on C(18) columns has been accomplished using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS RP-C(18) column (250 mm x 4.6 mm) and on a Waters C(18) Symmetry column (150 mm x 3.9mm), 5 microm particle size each. These columns were equilibrated with mobile phases consisted of methanol-acetonitrile-0.1M phosphate buffer pH 8.0 (12.5:12.5:75, v/v/v) and (15:15:70, v/v/v), respectively. The flow rate was 1.0 ml/min and the total elution time was 15 and 5 min, respectively. Both methods were applied to oxytetracycline raw material, human and veterinary formulations, where the excipients did not interfere. External standard calibration curves were linear for 4-epioxytetracycline, oxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline in the concentration range of 0.27-200 microM, 0.05-200 microM, 0.03-200 microM, 0.35-200 microM and 0.20-200 microM on column A and 0.08-200 microM, 0.15-200 microM, 0.09-200 microM, 0.25-200 microM and 0.47-200 microM on column B, respectively. Day-to-day relative standard deviation of the determination for every component was less than 3%. Concerning the first column, limits of detection and quantification of the above compounds were in the concentration ranges of 10-106 nM and 30-352 nM, respectively, whereas on the second column these ranges became 27-144 nM and 81-475 nM, respectively. Recovery of the separated compounds was 95-105%.

Simultaneous Liquid Chromatographic Determination of 10 Ultra-Violet Filters in Sunscreens.

PubMed

Wharton, Mary; Geary, Michael; O'Connor, Niamh; Curtin, Laura; Ketcher, Krystal

2015-09-01

A rapid HPLC method was developed for the simultaneous determination of 10 UV filters found in sunscreen. The following UV filters were analyzed in this method; 2-phenylbenzimidazole-5-sulfonic acid, benzophenone-3, isoamyl p-methoxycinnamate, 4-methylbenzylidene camphor, octocrylene, ethylhexyl dimethyl 4-aminobenzoic acid, ethylhexyl methoxycinnamate, butyl methoxydibenzoylmethane, ethylhexyl salicylate and homosalate. The method was developed on two columns; a Thermo Hypersil C18 BDS, 3 µm column (4.6 × 100 mm) and a Chromolith RP-18e Monolithic column (4.6 × 100 mm). The same mobile phase of ethanol and 1% acetic acid (70:30, v/v) was employed for both columns. The separation of the 10 UV filters was carried out successfully on both columns; the optimal resolution was obtained on the Thermo Scientific Hypersil column in a time frame of 7 min. An isocratic elution utilizing ethanol and acetic acid (70:30, v/v) at a temperature of 35°C was employed. The method was applied to a number of commercial samples of sunscreen and lotions and was validated according to International Conference on Harmonisation guidelines for selectivity, linearity, accuracy, precision and robustness. A comparison of the performances of both columns was also carried out. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Apparatus and process for the separation of hydrophobic and hydrophilic particles using microbubble column flotation together with a process and apparatus for generation of microbubbles

DOEpatents

Yoon, R.H.; Adel, G.T.; Luttrell, G.H.

1992-12-01

A method and apparatus are disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal and minerals, so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators. 14 figs.

[Advances of the coatings used in columns for capillary electrophoresis and in nanochannels of chips].

PubMed

Liu, Chunye; Chen, Jierong

2005-01-01

An overview is provided on the advancement and development of coating preparation methodology and materials used in capillaries and channels in microfluidic chip. Discussion is also given on the effects of coatings in the resolutions of separation and the reproducibility of separations. Dynamic coatings and linked coatings, classified as homo-polymers, copolymers and heterocyclic compounds, are further discussed, and so are the methods for the preparation of the coatings by cross-linked reaction, sol-gel process, photomodification and chemical deposition, etc. The discussion will be useful for the optimization of capillary columns that are used in capillary electrophoresis and nanochannels of chip.

Apparatus and process for the separation of hydrophobic and hydrophilic particles using microbubble column flotation together with a process and apparatus for generation of microbubbles

DOEpatents

Yoon, R.H.; Adel, G.T.; Luttrell, G.H.

1998-09-29

A method and apparatus are disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal and minerals, so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators. 14 figs.

Quantitative determination of p-aminosalicylic acid and its degradation product m-aminophenol in pellets by ion-pair high-performance liquid chromatography applying the monolithic Chromolith Speedrod RP-18e column.

PubMed

Vasbinder, E; Van der Weken, G; Vander Heyden, Y; Baeyens, W R G; Debunne, A; Remon, J P; García-Campaña, A M

2004-01-01

An ion-pair high performance liquid chromatographic method was developed for the simultaneous determination of p-aminosalicylic acid (PAS) and its degradation product m-aminophenol (MAP) in a newly developed multiparticular drug delivery system. Owing to the concentration differences of PAS and MAP, acetanilide and sulfanilic acid were used as internal standards, respectively. The separation was performed on a Chromolith SpeedROD RP-18e column, a new packing material consisting of monolithic rods of highly porous silica. The mobile phase composition was of 20 mm phosphate buffer, 20 mm tetrabutylammonium hydrogen sulphate and 16% (v/v) methanol adjusted to pH 6.8, at a flow-rate of 1.0 mL/min, resulting in a run-time of about 6 min. Detection was by UV at 233 nm. The method was validated and proved to be useful for stability testing of the new dosage form. Separation efficiency was compared between the new packing material Chromolith SpeedROD RP-18e and the conventional reversed-phase cartridge LiChroCART 125-4 (5 microm). A robustness test was carried out on both columns and different separation parameters (retention, resolution, run time, temperature) were determined. Copyright 2004 John Wiley & Sons, Ltd.

Neutral monosaccharide composition analysis of plant-derived oligo- and polysaccharides by high performance liquid chromatography.

PubMed

Yan, Jun; Shi, Songshan; Wang, Hongwei; Liu, Ruimin; Li, Ning; Chen, Yonglin; Wang, Shunchun

2016-01-20

A novel analytical method for neutral monosaccharide composition analysis of plant-derived oligo- and polysaccharides was developed using hydrophilic interaction liquid chromatography coupled to a charged aerosol detector. The effects of column type, additives, pH and column temperature on retention and separation were evaluated. Additionally, the method could distinguish potential impurities in samples, including chloride, sulfate and sodium, from sugars. The results of validation demonstrated that this method had good linearity (R(2) ≥ 0.9981), high precision (relative standard deviation ≤ 4.43%), and adequate accuracy (94.02-103.37% recovery) and sensitivity (detection limit: 15-40 ng). Finally, the monosaccharide compositions of the polysaccharide from Eclipta prostrasta L. and stachyose were successfully profiled through this method. This report represents the first time that all of these common monosaccharides could be well-separated and determined simultaneously by high performance liquid chromatography without additional derivatization. This newly developed method is convenient, efficient and reliable for monosaccharide analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chiral ligand-exchange high-performance liquid chromatography with copper (II)-L-phenylalanine complexes for separation of 3,4-dimethoxy-α-methylphenylalanine racemes.

PubMed

Jia, Dong-Xu; Ai, Zheng-Gui; Xue, Ya-Ping; Zheng, Yu-Guo

2014-11-01

L-3, 4-dimethoxy-α-methylphenylalanine (L-DMMD) is an important intermediate for the synthesis of 3-hydroxy-α-methyl-L-tyrosine (L-methyldopa). This paper describes an efficient, accurate, and low-priced method of high-performance liquid chromatography (HPLC) using chiral mobile phase and conventional C18 column to separate L-DMMD from its enantiomers. The effects of ligands, copper salts, organic modifiers, pHs of mobile phase, and temperatures on the retention factors (k') and selectivity (α) were evaluated to achieve optimal separation performance. Then, thermal analysis of the optimal separation conditions was investigated as well. It was confirmed that the optimal mobile phase was composed of 20 % (v/v) methanol, 8 mM L-phenylalanine (L-Phe), and 4 mM cupric sulfate in water of pH 3.2, and the column temperature was set at 20 °C. Baseline separation of two enantiomers could be obtained through the conventional C18 column with a resolution (R) of 3.18 in less than 18 min. Thermodynamic data (∆∆H and ∆∆S) obtained by Van't Hoff plots revealed the chiral separation was an enthalpy-controlled process. To the best of our knowledge, this is the first report regarding the enantioseparation of DMMD by chiral ligand-exchange HPLC.

On-line sample cleanup and enrichment chromatographic technique for the determination of ambroxol in human serum.

PubMed

Emara, Samy; Kamal, Maha; Abdel Kawi, Mohamed

2012-02-01

A sensitive and efficient on-line clean up and pre-concentration method has been developed using column-switching technique and protein-coated µ-Bondapak CN silica pre-column for quantification of ambroxol (AM) in human serum. The method is performed by direct injection of serum sample onto a protein-coated µ-Bondapak CN silica pre-column, where AM is pre-concentrated and retained, while proteins and very polar constituents are washed to waste using a phosphate buffer saline (pH 7.4). The retained analyte on the pre-column is directed onto a C(18) analytical column for separation, with a mobile phase consisting of a mixture of methanol and distilled deionized water (containing 1% triethylamine adjusted to pH 3.5 with ortho-phosphoric acid) in the ratio of 50:50 (v/v). Detection is performed at 254 nm. The calibration curve is linear over the concentration range of 12-120 ng/mL (r(2) = 0.9995). The recovery, selectivity, linearity, precision, and accuracy of the method are convenient for pharmacokinetic studies or routine assays.

Pretreatment method for immunoassay of polychlorinated biphenyls in transformer oil using multilayer capillary column and microfluidic liquid-liquid partitioning.

PubMed

Aota, Arata; Date, Yasumoto; Terakado, Shingo; Ohmura, Naoya

2013-01-01

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that are present in the insulating oil inside a large number of transformers. To aid in eliminating PCB-contaminated transformers, PCBs in oil need to be measured using a rapid and cost-effective analytical method. We previously reported a pretreatment method for the immunoassay of PCBs in oil using a large-scale multilayer column and a microchip with multiple microrecesses, which permitted concentrated solvent extraction. In this paper, we report on a more rapid and facile pretreatment method, without an evaporation process, by improving the column and the microchip. In a miniaturized column, the decomposition and separation of oil were completed in 2 min. PCBs can be eluted from the capillary column at concentrations seven-times higher than those from the previous column. The total volume of the microrecesses was increased by improving the microrecess structure, the enabling extraction of four-times the amount of PCBs achieved with the previous system. By interfacing the capillary column with the improved microchip, PCBs in the eluate from the column were extracted into dimethyl sulfoxide in microrecesses with high enrichment and without the need for evaporation. Pretreatment was completed within 20 min. The pretreated oil was analyzed using a flow-based kinetic exclusion immunoassay. The limit of detection of PCBs in oil was 0.15 mg kg(-1), which satisfies the criterion set in Japan of 0.5 mg kg(-1).

Comparison of ultrafiltration and solid phase extraction for the separation of free and protein-bound serum copper for the Wilson's disease diagnosis.

PubMed

Bohrer, Denise; Do Nascimento, Paulo Cícero; Ramirez, Adrian G; Mendonça, Jean Karlo A; De Carvalho, Leandro M; Pomblum, Solange Cristina G

2004-07-01

The determination of the ratio free/protein-bound serum copper along with urinary copper can be used as a preliminary test for the Wilson's Disease diagnosis. In this work, the determination of these copper fractions in serum samples was carried out in two different ways; after separation of the copper bound to proteins from the free fraction by a column for protein adsorption and by ultrafiltration. As proteins can be adsorbed onto plastic polymeric surfaces, polyethylene (PE) with different molecular weights in powder form was investigated for protein adsorption. A small column was adapted in a flow system to carry out a solid-phase extraction (SPE) on-line. Preliminary experiments defined conditions for protein retention and elution and column saturation. Good performance was achieved using Mg(NO3)2 solution as carrier and methanol as eluent. The presence of proteins in both fraction (column effluent and eluate) was checked by the Coomassie Brilliant Blue test. Copper was measured by graphite furnace atomic absorption spectrometry. The measurement in the column effluent furnished the free-fraction of copper while the copper measured in the eluate the bound-fraction. The method was compared with ultrafiltration (20 kDa), measuring the free-copper in the ultrafiltrate. For the determination of protein-bound copper, the copper found in the ultrafitrate was discounted from the total copper measured in the sample. Serum samples of 10 individuals were analyzed by both methods with good agreement of the results. The regression plots, obtained by analysing the samples by both methods, presented r2 and slope of 0.97 and 0.96 for free copper and 1.00 and 1.00 for bound copper, respectively. Protein-bound copper (PB) concentrations ranged from 74 to 2074 microg/l and free-copper (F) from 22 to 54 microg/l. The ratio F/PB, calculated from SPE data, was 29.7% for one individual, with Wilson Disease well-characterized, and ranged from 1.2% to 5.2% for the others. The SPE method performed well in terms of accuracy and precision, and showed good agreement with the UF. Advantages of SPE are small sample volume (50 microl), separation carried out in 10 min, and the use of the same column for several analyses. Copyright 2004 Elsevier B.V.

Separation of Be and Al for AMS using single-step column chromatography

NASA Astrophysics Data System (ADS)

Binnie, Steven A.; Dunai, Tibor J.; Voronina, Elena; Goral, Tomasz; Heinze, Stefan; Dewald, Alfred

2015-10-01

With the aim of simplifying AMS target preparation procedures for TCN measurements we tested a new extraction chromatography approach which couples an anion exchange resin (WBEC) to a chelating resin (Beryllium resin) to separate Be and Al from dissolved quartz samples. Results show that WBEC-Beryllium resin stacks can be used to provide high purity Be and Al separations using a combination of hydrochloric/oxalic and nitric acid elutions. 10Be and 26Al concentrations from quartz samples prepared using more standard procedures are compared with results from replicate samples prepared using the coupled WBEC-Beryllium resin approach and show good agreement. The new column procedure is performed in a single step, reducing sample preparation times relative to more traditional methods of TCN target production.

Accessible silanol sites - beneficial for the RP-HPLC separation of constitutional and diastereomeric azaspirovesamicol isomers.

PubMed

Wenzel, Barbara; Fischer, Steffen; Brust, Peter; Steinbach, Jörg

2010-12-10

Different RP-HPLC columns (phenyl, conventional ODS, cross-linked C(18) and special end-capped C(8) and C(18) phases) were used to investigate the separation of four basic ionizable isomers. Using ACN/20mM NH(4)OAc aq., a separation was observed exclusively on RP columns with higher silanol activity at unusual high ACN concentration, indicating cation-exchange as main retention mechanism. Using MeOH/20mM NH(4)OAc aq., another separation at low MeOH concentrations was observed on both, RP columns with higher as well as RP columns with lower silanol activity, which is mainly based on hydrophobic interactions. The isomers were also separated on a bare silica column at higher MeOH content using NH(4)OAc. Since cation-exchange governs this retention, the elution order was different compared to the RP phases. A strong retention on the silica column was observed in ACN, which could be attributed to partition processes as additional retention mechanism. Copyright © 2010 Elsevier B.V. All rights reserved.

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

Palmieri, M.D.; Fritz, J.S.

Metal ions are determined by adding N-methylfurohydroxamic acid to an aqueous sample and then separating the metal chelates by direct injection onto a liquid chromatographic column. Separations on a C/sub 8/ silica column and a polystyrene-divinylbenzene column are compared, with better separations seen on the polymeric column. The complexes formed at low pH values are cationic and are separated by an ion pairing mechanism. Retention times and selectivity of the metal complexes can be varied by changing the pH. Several metal ions can be separated and quantified; separation conditions, linear calibration curve ranges, and detection limits are presented for Zr(IV),more » Hf(IV), Fe(III), Nb(V), Al(III), and Sb(III). Interferences due to the presence of other ions in solution are investigated. Finally, an antiperspirant sample is analyzed for zirconium by high-performance liquid chromatography.« less

Antibody-immobilized column for quick cell separation based on cell rolling.

PubMed

Mahara, Atsushi; Yamaoka, Tetsuji

2010-01-01

Cell separation using methodological standards that ensure high purity is a very important step in cell transplantation for regenerative medicine and for stem cell research. A separation protocol using magnetic beads has been widely used for cell separation to isolate negative and positive cells. However, not only the surface marker pattern, e.g., negative or positive, but also the density of a cell depends on its developmental stage and differentiation ability. Rapid and label-free separation procedures based on surface marker density are the focus of our interest. In this study, we have successfully developed an antiCD34 antibody-immobilized cell-rolling column, that can separate cells depending on the CD34 density of the cell surfaces. Various conditions for the cell-rolling column were optimized including graft copolymerization, and adjustment of the column tilt angle, and medium flow rate. Using CD34-positive and -negative cell lines, the cell separation potential of the column was established. We observed a difference in the rolling velocities between CD34-positive and CD34-negative cells on antibody-immobilized microfluidic device. Cell separation was achieved by tilting the surface 20 degrees and the increasing medium flow. Surface marker characteristics of the isolated cells in each fraction were analyzed using a cell-sorting system, and it was found that populations containing high density of CD34 were eluted in the delayed fractions. These results demonstrate that cells with a given surface marker density can be continuously separated using the cell rolling column.

Detection of processed genetically modified food using CIM monolithic columns for DNA isolation.

PubMed

Jerman, Sergej; Podgornik, Ales; Cankar, Katarina; Cadet, Neza; Skrt, Mihaela; Zel, Jana; Raspor, Peter

2005-02-11

The availability of sufficient quantities of DNA of adequate quality is crucial in polymerase chain reaction (PCR)-based methods for genetically modified food detection. In this work, the suitability of anion-exchange CIM (Convective Interaction Media; BIA Separations, Ljubljana, Slovenia) monolithic columns for isolation of DNA from food was studied. Maize and its derivates corn meal and thermally pretreated corn meal were chosen as model food. Two commercially available CIM disk columns were tested: DEAE (diethylaminoethyl) and QA (quaternary amine). Preliminary separations were performed with standard solution of salmon DNA at different pH values and different NaCl concentrations in mobile phase. DEAE groups and pH 8 were chosen for further isolations of DNA from a complex matrix-food extract. The quality and quantity of isolated DNA were tested on agarose gel electrophoresis, with UV-scanning spectrophotometry, and by amplification with real-time PCR. DNA isolated in this way was of suitable quality for further PCR analyses. The described method is also applicable for DNA isolation from processed foods with decreased DNA content. Furthermore, it is more effective and less time-consuming in comparison with the existing proposed methods for isolation of DNA from plant-derived foods.

Preparative isolation of flavonoid glycosides from Sphaerophysa salsula using hydrophilic interaction solid-phase extraction coupled with two-dimensional preparative liquid chromatography.

PubMed

Jiao, Lijin; Tao, Yanduo; Wang, Weidong; Shao, Yun; Mei, Lijuan; Wang, Qilan; Dang, Jun

2017-10-01

An offline preparative two-dimensional reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography coupled with hydrophilic interaction solid-phase extraction method was developed for the preparative isolation of flavonoid glycosides from a crude sample of Sphaerophysa salsula. First, the non-flavonoids were removed using an XAmide solid-phase extraction cartridge. Based on the separation results of three different chromatographic stationary phases, the first-dimensional preparation was performed on an XAqua C18 prep column, and 15 fractions were obtained from the 5.2 g target sample. Then, three representative fractions were selected for additional purification on an XAmide preparative column to further isolate the flavonoid glycosides. In all, eight flavonoid glycosides were isolated in purities over 97%. The results demonstrated that the two-dimensional liquid chromatography method used in this study was effective for the preparative separation of flavonoid glycosides from Sphaerophysa salsula. Additionally, this method showed great potential for the separation of flavonoid glycosides from other plant materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fast analysis of curcuminoids from turmeric (Curcuma longa L.) by high-performance liquid chromatography using a fused-core column.

PubMed

Osorio-Tobón, J Felipe; Carvalho, Pedro I N; Barbero, Gerardo Fernández; Nogueira, Gislaine Chrystina; Rostagno, Mauricio Ariel; Meireles, Maria Angela de Almeida

2016-06-01

The recent development of fused-core technology in HPLC columns is enabling faster and highly efficient separations. This technology was evaluated for the development of a fast method for the analysis of main curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) present in extracts of turmeric (Curcuma longa L.). A step-by-step strategy was used to optimize temperature (40-55 °C), flow rate (1.0-2.5 mL min(-1)), mobile phase composition and equilibration time (1-5 min). A gradient method was developed using acidified water and acetonitrile combined with high column temperature (55 °C) and flow rate (2.5 mL min(-1)). Optimized conditions provided a method for the separation of these three curcuminoids in approximately 1.3 min with a total analysis time (sample-to-sample) of 7 min, including the clean-up and the re-equilibration of the column. Evaluation of chromatographic performance revealed excellent intraday and interday reproducibility (>99%), resolution (>2.23), selectivity (>1.12), peak symmetry (1.24-1.42) while presenting low limits of detection (<0.40 mg L(-1)) and quantification (<1.34 mg L(-1)). The robustness of the method was calculated according to the concentration/dilution of the sample and the injection volume. Several combinations of methanol and ethanol with water as sample solvents were evaluated and the best chromatographic results and extraction rate were obtained using 100% methanol. Finally, the developed method was validated with different extracts of turmeric rhizome and products that use turmeric in their formulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of an efficient fractionation method for the preparative separation of sesquiterpenoids from Tussilago farfara by counter-current chromatography.

PubMed

Song, Kwangho; Lee, Kyoung Jin; Kim, Yeong Shik

2017-03-17

A novel application of counter-current chromatography (CCC) to enrich plant extracts using direct and continuous injection (CCC-DCI) was developed to fractionate sesquiterpenoids from the buds of Tussilago farfara L. In this study, an n-hexane-acetonitrile-water (HAcW) solvent system was separately pumped into the CCC column, and an extraction solution (45% acetonitrile) was directly and continuously injected into the CCC column. Since the extraction solution was used as a mobile phase in this method, solvent consumption could be greatly reduced. To enrich the extraction solution (315.9g/5.4L), only 4.2L water, 4.6L acetonitrile, and 1.2L n-hexane were used, including the extraction step. Finally, 6.8g of a sesquiterpenoid-enriched (STE) fraction was obtained from the crude extract (315.9g) of Tussilago farfara (1kg) in a single CCC run with a separation time of 8.5h. The sample injection capacity of CCC-DCI was greater than 300g; this amount of sample could not be handled in conventional CCC or other fractionation methods with the same column volume. Moreover, three major sesquiterpenoids (1: tussilagone, 2: 14-acetoxy-7β-(3'-ethyl cis-crotonoyloxy)-1α-(2'-methylburyryloxy)-notonipetranone, and 3: 7β-(3'-ethyl cis-crotonoyloxy)-1α-(2'-methylburyryloxy)-3, 14-dehydro-Z-notonipetranone) were purified from the STE fraction by CCC, and their chemical structures were elucidated by 1 H NMR and 13 C NMR. A quantification study was conducted, and the contents of compounds 1-3 in the CCC-DCI fraction were higher than those of conventional multi-step fractionations performed in series: solvent partitioning and open column chromatography. Furthermore, the average CCC-DCI recoveries were 96.1% (1), 96.9% (2), and 94.6% (3), whereas the open column chromatography recoveries were 77.7% (1), 66.5% (2), and 58.4% (3). The developed method demonstrates that CCC is a useful technique for enriching target components from natural products. Copyright © 2017 Elsevier B.V. All rights reserved.

An automated online turboflow cleanup LC/MS/MS method for the determination of 11 plasticizers in beverages and milk.

PubMed

Ates, Ebru; Mittendorf, Klaus; Senyuva, Hamide

2013-01-01

An automated sample preparation technique involving cleanup and analytical separation in a single operation using an online coupled TurboFlow (RP-LC system) is reported. This method eliminates time-consuming sample preparation steps that can be potential sources for cross-contamination in the analysis of plasticizers. Using TurboFlow chromatography, liquid samples were injected directly into the automated system without previous extraction or cleanup. Special cleanup columns enabled specific binding of target compounds; higher MW compounds, i.e., fats and proteins, and other matrix interferences with different chemical properties were removed to waste, prior to LC/MS/MS. Systematic stepwise method development using this new technology in the food safety area is described. Selection of optimum columns and mobile phases for loading onto the cleanup column followed by transfer onto the analytical column and MS detection are critical method parameters. The method was optimized for the assay of 10 phthalates (dimethyl, diethyl, dipropyl, butyl benzyl, diisobutyl, dicyclohexyl, dihexyl, diethylhexyl, diisononyl, and diisododecyl) and one adipate (diethylhexyl) in beverages and milk.

Analysis and simulation of industrial distillation processes using a graphical system design model

NASA Astrophysics Data System (ADS)

Boca, Maria Loredana; Dobra, Remus; Dragos, Pasculescu; Ahmad, Mohammad Ayaz

2016-12-01

The separation column used for experimentations one model can be configured in two ways: one - two columns of different diameters placed one within the other extension, and second way, one column with set diameter [1], [2]. The column separates the carbon isotopes based on the cryogenic distillation of pure carbon monoxide, which is fed at a constant flow rate as a gas through the feeding system [1],[2]. Based on numerical control systems used in virtual instrumentation was done some simulations of the distillation process in order to obtain of the isotope 13C at high concentrations. The experimental installation for cryogenic separation can be configured from the point of view of the separation column in two ways: Cascade - two columns of different diameters and placed one in the extension of the other column, and second one column with a set diameter. It is proposed that this installation is controlled to achieve data using a data acquisition tool and professional software that will process information from the isotopic column based on a logical dedicated algorithm. Classical isotopic column will be controlled automatically, and information about the main parameters will be monitored and properly display using one program. Take in consideration the very-low operating temperature, an efficient thermal isolation vacuum jacket is necessary. Since the "elementary separation ratio" [2] is very close to unity in order to raise the (13C) isotope concentration up to a desired level, a permanent counter current of the liquid-gaseous phases of the carbon monoxide is created by the main elements of the equipment: the boiler in the bottom-side of the column and the condenser in the top-side.

Simultaneous enantioselective separation of polychlorinated biphenyls and their methyl sulfone metabolites by heart-cut MDGC: determination of enantiomeric fractions in fish oils and cow liver samples.

PubMed

Pérez-Fernández, Virginia; Castro-Puyana, María; González, María José; Marina, María Luisa; García, María Ángeles; Gómara, Belén

2012-07-01

The potential of three capillary columns based on β-cyclodextrin (i.e., Chirasil-Dex, BGB-172, and BGB-176SE) has been studied for the simultaneous enantiomeric separation of polychlorinated biphenyls (PCBs) and methylsulfonyl metabolites of PCBs (MeSO(2)-PCBs) employing a heart-cut multidimensional gas chromatographic system (heart-cut MDGC). Among the columns studied, the BGB-176SE capillary column provided the best results, allowing the simultaneous enantioselective resolution of six MeSO(2)-PCBs and six chiral PCBs; the Chirasil-Dex column did not resolve any of the studied MeSO(2)-PCBs; and a poor resolution was obtained for three MeSO(2)-PCBs when the BGB-172 column was employed. The developed method was successfully applied to two fish oil and one cow liver samples commercially available, which showed different enantioselective pattern. PCBs 91 and 176 presented a clear enrichment of the second eluted atropisomer in codfish oil, whereas in fish oil sample, slight enrichment of the first eluted atropisomer of CB45 and the second eluted atropisomer of CB136 were observed. © 2012 Wiley Periodicals, Inc.

Development and Optimisation of an HPLC-DAD-ESI-Q-ToF Method for the Determination of Phenolic Acids and Derivatives

PubMed Central

Restivo, Annalaura; Degano, Ilaria; Ribechini, Erika; Colombini, Maria Perla

2014-01-01

A method for the HPLC-MS/MS analysis of phenols, including phenolic acids and naphtoquinones, using an amide-embedded phase column was developed and compared to the literature methods based on classical C18 stationary phase columns. RP-Amide is a recently developed polar embedded stationary phase, whose wetting properties mean that up to 100% water can be used as an eluent. The increased retention and selectivity for polar compounds and the possibility of working in 100% water conditions make this column particularly interesting for the HPLC analysis of phenolic acids and derivatives. In this study, the chromatographic separation was optimised on an HPLC-DAD, and was used to separate 13 standard phenolic acids and derivatives. The method was validated on an HPLC-ESI-Q-ToF. The acquisition was performed in negative polarity and MS/MS target mode. Ionisation conditions and acquisition parameters for the Q-ToF detector were investigated by working on collision energies and fragmentor potentials. The performance of the method was fully evaluated on standards. Moreover, several raw materials containing phenols were analysed: walnut, gall, wine, malbec grape, French oak, red henna and propolis. Our method allowed us to characterize the phenolic composition in a wide range of matrices and to highlight possible matrix effects. PMID:24551158

Modeling of rotating disc contactor (RDC) column

NASA Astrophysics Data System (ADS)

Ismail, Wan Nurul Aiffah; Zakaria, Siti Aisyah; Noor, Nor Fashihah Mohd; Sulong, Ibrahim; Arshad, Khairil Anuar

2014-12-01

Liquid-liquid extraction is one of the most important separation processes. Different kinds of liquid-liquid extractor such as Rotating Disc Contactor (RDC) Column being used in industries. The study of liquid-liquid extraction in an RDC column has become a very important subject to be discussed not just among chemical engineers but mathematician as well. In this research, the modeling of small diameter RDC column using the chemical system involving cumene/isobutryric asid/water are analyzed by the method of Artificial Neural Network (ANN). In the previous research, we begin the process of analyzed the data using methods of design of the experiments (DOE) to identify which factor and their interaction factor are significant and to determine the percentage of contribution of the variance for each factor. From the result obtained, we continue the research by discussed the development and validation of an artificial neural network model in estimating the concentration of continuous and concentration of dispersed outlet for an RDC column. It is expected that an efficient and reliable model will be formed to predict RDC column performance as an alternative to speed up the simulation process.

Sol-gel technique for the preparation of beta-cyclodextrin derivative stationary phase in open-tubular capillary electrochromatography.

PubMed

Wang, Y; Zeng, Z; Guan, N; Cheng, J

2001-07-01

A novel open-tubular capillary electrochromatography (OT-CEC) column coated with 2,6-dibutyl-beta-cyclodextrin (DB-beta-CD) was prepared using sol-gel technique. In the sol-gel approach, owing to the three-dimensional network of sol-gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. We achieved high efficiencies of 5-14 x 10(4) plates/m for the isomeric nitrophenols using the sol-gel-derived DB-beta-CD columns. The migration time reproducibility of the separation of the isomeric nitrophenols was better than 2.2% over five runs and 4.5% from column to column. These sol-gel-coated DB-beta-CD columns have shown improved separations of isomeric aminophenols, isomeric dihydroxybenzenes and isomeric nitrophenols, in comparison with the sol-gel matrix capillary column. The influences of buffer pH and methanol solvent on separation were investigated. The chiral resolution of enantiomers such as ibuprofen and binaphthol was explored primarily.

Methods of producing cesium-131

DOEpatents

Meikrantz, David H; Snyder, John R

2012-09-18

Methods of producing cesium-131. The method comprises dissolving at least one non-irradiated barium source in water or a nitric acid solution to produce a barium target solution. The barium target solution is irradiated with neutron radiation to produce cesium-131, which is removed from the barium target solution. The cesium-131 is complexed with a calixarene compound to separate the cesium-131 from the barium target solution. A liquid:liquid extraction device or extraction column is used to separate the cesium-131 from the barium target solution.

A chiral HPLC method for the simultaneous separation of configurational isomers of the predominant cis/trans forms of astaxanthin.

PubMed

Abu-Lafi, S; Turujman, S A

1997-01-01

We report an HPLC method that allows the simultaneous separation of configurational isomers of the predominant cis/trans forms of astaxanthin. The configurational isomers of the all-trans-, and most of the configurational isomers of the 9-cis-, 13-cis- and 15-cis-astaxanthin were separated on a Sumichiral OA-2000 column, which is manufactured and packed in Japan with a Pirkle covalent D-phenylglycine chiral stationary phase (CSP). The large separation of the cis isomers from the all-trans isomers that we report here ensure the suitability of this method for the routine determination of the ratio of the configurational isomers of all-trans-astaxanthin.

Chromatographic column evaluation for the untargeted profiling of glucosinolates in cauliflower by means of ultra-high performance liquid chromatography coupled to high resolution mass spectrometry.

PubMed

Capriotti, Anna Laura; Cavaliere, Chiara; La Barbera, Giorgia; Montone, Carmela Maria; Piovesana, Susy; Zenezini Chiozzi, Riccardo; Laganà, Aldo

2018-03-01

The untargeted profiling is a promising approach for the characterization of secondary metabolites in biological matrices. Thanks to the recent rapid development of high-resolution mass spectrometry (HRMS) instrumentations, the number of applications by untargeted approaches for biological samples profiling has widely increased in the recent years. Despite the high potentialities of HRMS, however, a major issue in natural products analysis often arises in the upstream process of compounds separation. A separation technique is necessary to avoid phenomena such as signal suppression, and it is especially needed in the presence of isomeric metabolites, which are otherwise indistinguishable. Glucosinolates (GLSs), a group of secondary metabolites widely distributed among plants, resulted to be associated to the prevention of some serious diseases, such as cancer. This led to the development of several methods for the analysis of GLSs in vegetables tissues. The issue of GLSs chromatographic separation has been widely studied in the past because of the difficulty in the analysis of this highly polar and variable class of compounds. Several alternatives to reversed phase (RP) chromatography, sometimes not compatible with the coupling of liquid chromatography with mass spectrometry, have been tested for the analysis of intact GLSs. However, the availability of new stationary phases, in the last years, could allow the re-evaluation of RP chromatography for the analysis of intact GLSs. In this work, a thorough evaluation of four RP chromatographic columns for the analysis of GLSs in cauliflower (Brassica oleracea L. var. botrytis) extracts by an ultra-high performance liquid chromatographic system coupled via electrospray source to a hybrid quadrupole-Orbitrap mass spectrometer is presented. The columns tested were the following: one column Luna Omega polar C 18 , one column Kinetex Biphenyl, one column Kinetex core-shell XB-C 18 , two columns Kinetex core-shell XB-C 18 . After a previous optimization of the extraction method, cauliflower extracts were analyzed testing four different mobile phases onto the four columns for a total of sixteen different chromatographic conditions. The chromatographic systems were evaluated based on the number of detected and tentatively identified GLSs. Luna Polar stationary phase resulted to be the most suitable for the analysis of GLSs compared to Kinetex XB and Kinetex Biphenyl columns stationary phase. However, two in series Kinetex XB columns increased the number of tentatively identified GLSs compared to one Kinetex XB, showing the importance of column length in the analysis of complex mixtures. The data obtained with the best chromatographic system were deeply analyzed by MS/MS investigation for the final identification. Fiflty-one GLSs were tentatively identified, 24 of which have never been identified in cauliflower. Finally the linearity of the analytes response over the analyzed range of concentration was checked, suggesting that the developed method is suitable for both qualitative and quantitative analysis of GLSs in phytochemical mixtures. Copyright © 2017 Elsevier B.V. All rights reserved.

Cross flow cyclonic flotation column for coal and minerals beneficiation

DOEpatents

Lai, Ralph W.; Patton, Robert A.

2000-01-01

An apparatus and process for the separation of coal from pyritic impurities using a modified froth flotation system. The froth flotation column incorporates a helical track about the inner wall of the column in a region intermediate between the top and base of the column. A standard impeller located about the central axis of the column is used to generate a centrifugal force thereby increasing the separation efficiency of coal from the pyritic particles and hydrophillic tailings.

Liquid membrane coated ion-exchange column solids

DOEpatents

Barkey, Dale P.

1988-01-01

This invention relates to a method for improving the performance of liquid membrane separations by coating a liquid membrane onto solid ion-exchange resin beads in a fixed bed. Ion-exchange beads fabricated from an ion-exchange resin are swelled with water and are coated with a liquid membrane material that forms a film over the beads. The beads constitute a fixed bed ion-exchange column. Fluid being treated that contains the desired ion to be trapped by the ion-exchange particle is passed through the column. A carrier molecule, contained in the liquid membrane ion-exchange material, is selective for the desired ion in the fluid. The carrier molecule forms a complex with the desired ion, transporting it through the membrane and thus separating it from the other ions. The solution is fed continuously until breakthrough occurs at which time the ion is recovered, and the bed is regenerated.

Liquid membrane coated ion-exchange column solids

DOEpatents

Barkey, Dale P.

1989-01-01

This invention relates to a method for improving the performance of liquid embrane separations by coating a liquid membrane onto solid ion-exchange resin beads in a fixed bed. Ion-exchange beads fabricated from an ion-exchange resin are swelled with water and are coated with a liquid membrane material that forms a film over the beads. The beads constitute a fixed bed ion-exchange column. Fluid being treated that contains the desired ion to be trapped by the ion-exchange particle is passed through the column. A carrier molecule, contained in the liquid membrane ion-exchange material, is selected for the desired ion in the fluid. The carrier molecule forms a complex with the desired ion, transporting it through the membrane and thus separating it from the other ions. The solution is fed continuously until breakthrough occurs at which time the ion is recovered, and the bed is regenerated.

Separation of actinides using capillary extraction chromatography-inductively coupled plasma mass spectrometry.

PubMed

Peterson, Dominic S; Montoya, Velma M

2009-08-01

Trace levels of actinides have been separated on capillary extraction chromatography columns. Detection of the actinides was achieved using an inductively coupled plasma mass spectrometer, which was coupled with the extraction chromatography system. In this study, we compare 30-cm long, 4.6 mm i.d. columns to capillary columns (750 microm i.d.) with lengths from 30 cm up to 150 cm. The columns that were tested were packed with TRU resin. We were able to separate a mixture of five actinides ((232)Th, (238)U, (237)Np, (239)Pu, and (241)Am). This work has application to rapid bioassay as well as automated separations of actinide materials.

Method of separating short half-life radionuclides from a mixture of radionuclides

DOEpatents

Bray, Lane A.; Ryan, Jack L.

1999-01-01

The present invention is a method of removing an impurity of plutonium, lead or a combination thereof from a mixture of radionuclides that contains the impurity and at least one parent radionuclide. The method has the steps of (a) insuring that the mixture is a hydrochloric acid mixture; (b) oxidizing the acidic mixture and specifically oxidizing the impurity to its highest oxidation state; and (c) passing the oxidized mixture through a chloride form anion exchange column whereupon the oxidized impurity absorbs to the chloride form anion exchange column and the 22.sup.9 Th or 2.sup.27 Ac "cow" radionuclide passes through the chloride form anion exchange column. The plutonium is removed for the purpose of obtaining other alpha emitting radionuclides in a highly purified form suitable for medical therapy. In addition to plutonium; lead, iron, cobalt, copper, uranium, and other metallic cations that form chloride anionic complexes that may be present in the mixture; are removed from the mixture on the chloride form anion exchange column.

Method of separating short half-life radionuclides from a mixture of radionuclides

DOEpatents

Bray, L.A.; Ryan, J.L.

1999-03-23

The present invention is a method of removing an impurity of plutonium, lead or a combination thereof from a mixture of radionuclides that contains the impurity and at least one parent radionuclide. The method has the steps of (a) insuring that the mixture is a hydrochloric acid mixture; (b) oxidizing the acidic mixture and specifically oxidizing the impurity to its highest oxidation state; and (c) passing the oxidized mixture through a chloride form anion exchange column whereupon the oxidized impurity absorbs to the chloride form anion exchange column and the {sup 229}Th or {sup 227}Ac ``cow`` radionuclide passes through the chloride form anion exchange column. The plutonium is removed for the purpose of obtaining other alpha emitting radionuclides in a highly purified form suitable for medical therapy. In addition to plutonium, lead, iron, cobalt, copper, uranium, and other metallic cations that form chloride anionic complexes that may be present in the mixture are removed from the mixture on the chloride form anion exchange column. 8 figs.

Mathematical analysis of frontal affinity chromatography in particle and membrane configurations.

PubMed

Tejeda-Mansir, A; Montesinos, R M; Guzmán, R

2001-10-30

The scaleup and optimization of large-scale affinity-chromatographic operations in the recovery, separation and purification of biochemical components is of major industrial importance. The development of mathematical models to describe affinity-chromatographic processes, and the use of these models in computer programs to predict column performance is an engineering approach that can help to attain these bioprocess engineering tasks successfully. Most affinity-chromatographic separations are operated in the frontal mode, using fixed-bed columns. Purely diffusive and perfusion particles and membrane-based affinity chromatography are among the main commercially available technologies for these separations. For a particular application, a basic understanding of the main similarities and differences between particle and membrane frontal affinity chromatography and how these characteristics are reflected in the transport models is of fundamental relevance. This review presents the basic theoretical considerations used in the development of particle and membrane affinity chromatography models that can be applied in the design and operation of large-scale affinity separations in fixed-bed columns. A transport model for column affinity chromatography that considers column dispersion, particle internal convection, external film resistance, finite kinetic rate, plus macropore and micropore resistances is analyzed as a framework for exploring further the mathematical analysis. Such models provide a general realistic description of almost all practical systems. Specific mathematical models that take into account geometric considerations and transport effects have been developed for both particle and membrane affinity chromatography systems. Some of the most common simplified models, based on linear driving-force (LDF) and equilibrium assumptions, are emphasized. Analytical solutions of the corresponding simplified dimensionless affinity models are presented. Particular methods for estimating the parameters that characterize the mass-transfer and adsorption mechanisms in affinity systems are described.

Separation of carbohydrates using hydrophilic interaction liquid chromatography.

PubMed

Fu, Qing; Liang, Tu; Li, Zhenyu; Xu, Xiaoyong; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

2013-09-20

A strategy was developed to rapidly evaluate chromatographic properties of hydrophilic interaction chromatography (HILIC) columns for separating carbohydrates. Seven HILIC columns (Silica, Diol, TSK Amide-80, XAmide, Click Maltose, Click β-CD, and Click TE-Cys columns) were evaluated by using three monosaccharide and seven disaccharides as probes. The influence of column temperature on the peak shape and tautomerization of carbohydrates, as well as column selectivity were investigated. The influence of surface charge property on the retention was also studied by using glucose, glucuronic acid, and glucosamine, which indicated that buffer salt concentration and pH value in mobile phase was necessary to control the ionic interactions between ionic carbohydrates and HILIC columns. According to evaluation results, the XAmide column was selected as an example to establish experimental schemes for separation of complex mixtures of oligosaccharide. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pushing the speed limit in enantioselective supercritical fluid chromatography.

PubMed

Regalado, Erik L; Welch, Christopher J

2015-08-01

Chromatographic enantioseparations on the order of a few seconds can be achieved by supercritical fluid chromatography using short columns packed with chiral stationary phases. The evolution of 'world record' speeds for the chromatographic separation of enantiomers has steadily dropped from an industry standard of 20-40 min just two decades ago, to a current ability to perform many enantioseparations in well under a minute. Improvements in instrument and column technologies enabled this revolution, but the ability to predict optimal separation time from an initial method development screening assay using the t(min cc) predictor greatly simplifies the development and optimization of high-speed chiral chromatographic separations. In this study, we illustrate how the use of this simple tool in combination with the workhorse technique of supercritical fluid chromatography on customized short chiral columns (1-2 cm length) allows us to achieve ultrafast enantioseparations of pharmaceutically relevant compounds on the 5-20 s scale, bringing the technique of high-throughput enantiopurity analysis out of the specialist realm and into the laboratories of most researchers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identification of column edges of DNA fragments by using K-means clustering and mean algorithm on lane histograms of DNA agarose gel electrophoresis images

NASA Astrophysics Data System (ADS)

Turan, Muhammed K.; Sehirli, Eftal; Elen, Abdullah; Karas, Ismail R.

2015-07-01

Gel electrophoresis (GE) is one of the most used method to separate DNA, RNA, protein molecules according to size, weight and quantity parameters in many areas such as genetics, molecular biology, biochemistry, microbiology. The main way to separate each molecule is to find borders of each molecule fragment. This paper presents a software application that show columns edges of DNA fragments in 3 steps. In the first step the application obtains lane histograms of agarose gel electrophoresis images by doing projection based on x-axis. In the second step, it utilizes k-means clustering algorithm to classify point values of lane histogram such as left side values, right side values and undesired values. In the third step, column edges of DNA fragments is shown by using mean algorithm and mathematical processes to separate DNA fragments from the background in a fully automated way. In addition to this, the application presents locations of DNA fragments and how many DNA fragments exist on images captured by a scientific camera.

Method for the routine quantitative gas chromatographic analysis of major free fatty acids in butter and cream.

PubMed

Woo, A H; Lindsay, R C

1980-07-01

A rapid quantiative method was developed for routine analysis of the major, even carbon-numbered free fatty acids in butter and cream. Free fatty acids were isolated directly from intact samples by a modified silicic acid-potassium hydroxide arrestant column and were separated by gas chromatography with a 1.8 m x 2 mm inner diameter glass column packed with 10% neopentyl glycol adipate on 80/100 Chromosorb W. Purified, formic acid-saturated carrier gas was required for minimal peak tailing and extended column life. The accuracy and reproducibility of the mmethod was established through quantitative recovery studies of free fatty acid mixtures, free fatty acids added to butter, and replicate analysis of butter and cream samples.

Practical comparison of LC columns packed with different superficially porous particles for the separation of small molecules and medium size natural products.

PubMed

Yang, Peilin; McCabe, Terry; Pursch, Matthias

2011-11-01

Commercial C(18) columns packed with superficially porous particles of different sizes and shell thicknesses (Ascentis Express, Kinetex, and Poroshell 120) or sub-2-μm totally porous particles (Acquity BEH) were systematically compared using a small molecule mixture and a complex natural product mixture as text probes. Significant efficiency loss was observed on 2.1-mm id columns even with a low dispersion ultra-high pressure liquid chromatography system. The Kinetex 4.6-mm id column packed with 2.6-μm particles exhibited the best overall efficiency for small molecule separations and the Poroshell 120 column showed better performance for mid-size natural product analytes. The Kinetex 2.1-mm id column packed with 1.7-μm particles did not deliver the expected performance and the possible reasons besides extra column effect have been proved to be frictional heating effect and poor column packing quality. Different column retentivities and selectivities have been observed on the four C(18) columns of different brands for the natural product separation. Column batch-to-batch variability that has been previously observed on the Ascentis Express column was also observed on the Kinetex and Poroshell 120 column. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A unified classification of stationary phases for packed column supercritical fluid chromatography.

PubMed

West, C; Lesellier, E

2008-05-16

The use of supercritical fluids as chromatographic mobile phases allows to obtain rapid separations with high efficiency on packed columns, which could favour the replacement of numerous HPLC methods by supercritical fluid chromatography (SFC) ones. Moreover, despite some unexpected chromatographic behaviours, general retention rules are now well understood, and mainly depend on the nature of the stationary phase. The use of polar stationary phases improves the retention of polar compounds, when C18-bonded silica favours the retention of hydrocarbonaceous compounds. In this sense, reversed-phase and normal-phase chromatography can be achieved in SFC, as in HPLC. However, these two domains are clearly separated in HPLC due to the opposite polarity of the mobile phases used for each method. In SFC, the same mobile phase can be used with both polar and non-polar stationary phases. Consequently, the need for a novel classification of stationary phases in SFC appears, allowing a unification of the classical reversed- and normal-phase domains. In this objective, the paper presents the development of a five-dimensional classification based on retention data for 94-111 solutes, using 28 commercially available columns representative of three major types of stationary phases. This classification diagram is based on a linear solvation energy relationship, on the use of solvation vectors and the calculation of similarity factors between the different chromatographic systems. This classification will be of great help in the choice of the well-suited stationary phase, either in regards of a particular separation or to improve the coupling of columns with complementary properties.

Harnessing mass differential confinement effects in magnetized rotating plasmas to address new separation needs

NASA Astrophysics Data System (ADS)

Gueroult, R.; Rax, J.-M.; Zweben, S. J.; Fisch, N. J.

2018-01-01

The ability to separate large volumes of mixed species based on atomic mass appears desirable for a variety of emerging applications with high societal impact. One possibility to meet this objective consists in leveraging mass differential effects in rotating plasmas. Beyond conventional centrifugation, rotating plasmas offer in principle additional ways to separate elements based on mass. Single ion orbits show that ion radial mass separation in a uniform magnetized plasma column can be achieved by applying a tailored electric potential profile across the column, or by driving a rotating magnetic field within the column. Furthermore, magnetic pressure and centrifugal effects can be combined in a non-uniform geometry to separate ions based on mass along the field lines. Practical application of these separation schemes hinges on the ability to produce the desirable electric and magnetic field configuration within the plasma column.

Quantification of N-acetyl- and N-glycolylneuraminic acids by a stable isotope dilution assay using high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Allevi, Pietro; Femia, Eti Alessandra; Costa, Maria Letizia; Cazzola, Roberta; Anastasia, Mario

2008-11-28

The present report describes a method for the quantification of N-acetyl- and N-glycolylneuraminic acids without any derivatization, using their (13)C(3)-isotopologues as internal standards and a C(18) reversed-phase column modified by decylboronic acid which allows for the first time a complete chromatographic separation between the two analytes. The method is based on high-performance liquid chromatographic coupled with electrospray ion-trap mass spectrometry. The limit of quantification of the method is 0.1mg/L (2.0ng on column) for both analytes. The calibration curves are linear for both sialic acids over the range of 0.1-80mg/L (2.0-1600ng on column) with a correlation coefficient greater than 0.997. The proposed method was applied to the quantitative determination of sialic acids released from fetuin as a model of glycoproteins.

Quantitative high-performance liquid chromatographic determination of retinoids in human serum using on-line solid-phase extraction and column switching. Determination of 9-cis-retinoic acid, 13-cis-retinoic acid, all-trans-retinoic acid, 4-oxo-all-trans-retinoicacid and 4-oxo-13-cis-retinoic acid.

PubMed

Gundersen, T E; Lundanes, E; Blomhoff, R

1997-03-28

A fully automated isocratic high-performance liquid chromatographic method for the determination of 9-cis-retinoic acid, 13-cis-retinoic acid, all-trans-retinoic acid, 4-oxo-13-cis-retinoic acid and 4-oxo-all-trans-retinoic acid, has been developed using on-line solid-phase extraction and a column switching technique allowing clean-up and pre-concentration in a single step. A 500-microliter sample of serum was diluted with 750 microliters of a solution containing 20% acetonitrile and the internal standard 9,10-dimethylanthracene. About 1000 microliters of this mixture was injected on a 20 x 4.6 mm I.D. poly ether ether ketone (PEEK) pre-column with titanium frits packed with Bondapak C18, 37-53 microns, 300 A particles. Proteins and very polar compounds were washed out to waste, from the pre-column, with 0.05% trifluoroacetic acid (TFA)-acetonitrile (8.5:1.5, v/v). More than 200 aliquots of diluted serum could be injected on this pre-column before elevated back-pressure enforces replacement. Components retained on the pre-column were backflushed to the analytical column for separation and detection at 360 nm. Baseline separation was achieved using a single 250 x 4.6 mm I.D. Suplex pKb-100 column and a mobile phase containing 69:10:2:16:3 (v/v) of acetonitrile-methanol-n-butanol-2% ammonium acetate-glacial acetic acid. A total time of analysis of less than 30 min, including sample preparation, was achieved. Recoveries were in the range of 79-86%. The limit of detection was 1-7 ng/ml serum and the precision, in the concentration range 20-1000 ng/ml, was between 1.3 and 4.5% for all five compounds. The method was applied for the analysis of human serum after oral administration of 60 mg Roaccutan. The method is well suited for pharmacological studies, while the endogenous levels of some retinoic acid isomers are below the limit of quantitation.

Fabrication of zeolitic imidazolate framework-8-methacrylate monolith composite capillary columns for fast gas chromatographic separation of small molecules.

PubMed

Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

2015-08-07

A composite zeolitic imidazolate framework-8 (ZIF-8) with a butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.) was fabricated to enhance the separation efficiency of methacrylate monoliths toward small molecules using conventional low-pressure gas chromatography in comparison with a neat butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.). The addition of 10mgmL(-1) ZIF-8 micro-particles increased the BET surface area of BuMA-co-EDMA by 3.4-fold. A fast separation of five linear alkanes in 36s with high resolution (Rs≥1.3) was performed using temperature program. Isothermal separation of the same sample also showed a high efficiency (3315platesm(-1) for octane) at 0.89min. Moreover, the column was able to separate skeletal isomers, such as iso-octane/octane and 2-methyl octane/nonane. In addition, an iso-butane/iso-butylene gas mixture was separated at ambient temperature. Comparison with an open tubular TR-5MS column (30m long×250μm i.d.) revealed the superiority of the composite column in separating the five-membered linear alkane mixture with 4-5 times increase in efficiency and a total separation time of 0.89min instead of 4.67min. A paint thinner sample was fully separated using the composite column in 2.43min with a good resolution (Rs≥0.89). The perfect combination between the polymeric monolith, with its high permeability, and ZIF-8, with its high surface area and flexible 0.34nm pore openings, led to the fast separation of small molecules with high efficiency and opened a new horizon in GC applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching

NASA Astrophysics Data System (ADS)

Du, Juan; Fa, Yun; Zheng, Yue; Li, Xuebing; Du, Fanglin; Yang, Haiyan

2014-05-01

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.

Comparison of high-performance liquid chromatography separation of red wine anthocyanins on a mixed-mode ion-exchange reversed-phase and on a reversed-phase column.

PubMed

Vergara, Carola; Mardones, Claudia; Hermosín-Gutiérrez, Isidro; von Baer, Dietrich

2010-09-03

Anthocyanins, which confer the characteristic color to red wine, can be used as markers to classify wines according to the grape variety. It is a complex separation that requires very high chromatographic efficiency, especially in the case of aged red wines, due to the formation of pyranoanthocyanins. A coelution between these kinds of compounds can affect the R(ac/coum) ratio of aged wines, and might lead to false results when classifying the wine variety. In 2007, the use of a novel mixed-mode ion-exchange reversed-phase column was reported to separate anthocyanins extracted from grapes of Vitis labrusca with different selectivity than C-18 columns. In the present work, the separation of anthocyanins including pyranoanthocyanins in young and aged Cabernet Sauvignon wines and other varieties is evaluated. The most interesting contributions of this research are the different elution order and selectivity obtained for anthocyanins and pyranoanthocyanins (only formed in wine), compared with those observed in C-18 stationary phases. Also interesting is the separation of the polymeric fraction, which elutes as a clearly separated peak at the chromatogram's end. However, a comparison with a high efficiency C-18 column with the same dimensions and particle size demonstrated that the tested mixed-mode column shows broader peaks with a theoretical plate number below 8000, for malvidin-3-glucoside peak, while it can be up to 10 times higher for a high efficiency C-18 column, depending on the column manufacturer. Under the tested conditions, in mixed-mode phase, the analysis time is almost twice that of a C-18 column with the same dimensions and particle size. A mixed-mode phase with increased efficiency should provide an interesting perspective for separation of anthocyanins in wine, due to its improved selectivity, combined with a useful role in a second-dimension separation in preparative anthocyanin chromatography. 2010 Elsevier B.V. All rights reserved.

On-Chip Microfluidic Components for In Situ Analysis, Separation, and Detection of Amino Acids

NASA Technical Reports Server (NTRS)

Zheng, Yun; Getty, Stephanie; Dworkin, Jason; Balvin, Manuel; Kotecki, Carl

2013-01-01

The Astrobiology Analytical Laboratory at GSFC has identified amino acids in meteorites and returned cometary samples by using liquid chromatography-electrospray ionization time-of-flight mass spectrometry (LCMS). These organic species are key markers for life, having the property of chirality that can be used to distinguish biological from non-biological amino acids. One of the critical components in the benchtop instrument is liquid chromatography (LC) analytical column. The commercial LC analytical column is an over- 250-mm-long and 4.6-mm-diameter stainless steel tube filled with functionized microbeads as stationary phase to separate the molecular species based on their chemistry. Miniaturization of this technique for spaceflight is compelling for future payloads for landed missions targeting astrobiology objectives. A commercial liquid chromatography analytical column consists of an inert cylindrical tube filled with a stationary phase, i.e., microbeads, that has been functionalized with a targeted chemistry. When analyte is sent through the column by a pressurized carrier fluid (typically a methanol/ water mixture), compounds are separated in time due to differences in chemical interactions with the stationary phase. Different species of analyte molecules will interact more strongly with the column chemistry, and will therefore take longer to traverse the column. In this way, the column will separate molecular species based on their chemistry. A lab-on-chip liquid analysis tool was developed. The microfluidic analytical column is capable of chromatographically separating biologically relevant classes of molecules based on their chemistry. For this analytical column, fabrication, low leak rate, and stationary phase incorporation of a serpentine microchannel were demonstrated that mimic the dimensions of a commercial LC column within a 5 10 1 mm chip. The microchannel in the chip has a 75- micrometer-diameter oval-shaped cross section. The serpentine microchannel has four different lengths: 40, 60, 80, and 100 mm. Functionized microbeads were filled inside the microchannel to separate molecular species based on their chemistry.

Quantitative analysis of retinoids in biological fluids by high-performance liquid chromatography using column switching. I. Determination of isotretinoin and tretinoin and their 4-oxo metabolites in plasma.

PubMed

Wyss, R; Bucheli, F

1988-02-26

A fully automated gradient high-performance liquid chromatographic method for the determination of isotretinoin, tretinoin and their 4-oxo metabolites in plasma was developed, using the column-switching technique. After dilution with an internal standard solution containing 20% acetonitrile, 0.5 ml of the sample was injected onto a precolumn (17 X 4.6 mm I.D.), filled with C18 Corasil 37-53 micron. Proteins and polar plasma components were washed out using 1% ammonium acetate-acetonitrile (9:1, v/v) as mobile phase 1. After valve switching, the retained components were transferred to the analytical column in the backflush mode, separated by gradient elution and detected at 360 nm by UV detection. Using two coupled reversed-phase columns (125 mm long), the separation of cis and trans isomers was possible, and all four compounds could be quantified down to 2 ng/ml of plasma. The inter-assay precision in the concentration range 20-100 ng/ml was between 1.0 and 4.7% for all compounds.

Integrated enzyme reactor and high resolving chromatography in "sub-chip" dimensions for sensitive protein mass spectrometry.

PubMed

Hustoft, Hanne Kolsrud; Brandtzaeg, Ole Kristian; Rogeberg, Magnus; Misaghian, Dorna; Torsetnes, Silje Bøen; Greibrokk, Tyge; Reubsaet, Léon; Wilson, Steven Ray; Lundanes, Elsa

2013-12-16

Reliable, sensitive and automatable analytical methodology is of great value in e.g. cancer diagnostics. In this context, an on-line system for enzymatic cleavage of proteins, subsequent peptide separation by liquid chromatography (LC) with mass spectrometric detection has been developed using "sub-chip" columns (10-20 μm inner diameter, ID). The system could detect attomole amounts of isolated cancer biomarker progastrin-releasing peptide (ProGRP), in a more automatable fashion compared to previous methods. The workflow combines protein digestion using an 20 μm ID immobilized trypsin reactor with a polymeric layer of 2-hydroxyethyl methacrylate-vinyl azlactone (HEMA-VDM), desalting on a polystyrene-divinylbenzene (PS-DVB) monolithic trap column, and subsequent separation of resulting peptides on a 10 μm ID (PS-DVB) porous layer open tubular (PLOT) column. The high resolution of the PLOT columns was maintained in the on-line system, resulting in narrow chromatographic peaks of 3-5 seconds. The trypsin reactors provided repeatable performance and were compatible with long-term storage.

Selection of stationary phase particle geometry using X-ray computed tomography and computational fluid dynamics simulations.

PubMed

Schmidt, Irma; Minceva, Mirjana; Arlt, Wolfgang

2012-02-17

The X-ray computed tomography (CT) is used to determine local parameters related to the column packing homogeneity and hydrodynamics in columns packed with spherically and irregularly shaped particles of same size. The results showed that the variation of porosity and axial dispersion coefficient along the column axis is insignificant, compared to their radial distribution. The methodology of using the data attained by CT measurements to perform a CFD simulation of a batch separation of model binary mixtures, with different concentration and separation factors is demonstrated. The results of the CFD simulation study show that columns packed with spherically shaped particles provide higher yield in comparison to columns packed with irregularly shaped particles only below a certain value of the separation factor. The presented methodology can be used for selecting a suited packing material for a particular separation task. Copyright © 2012 Elsevier B.V. All rights reserved.

Semi-industrial experimental study on bauxite separation using a cell-column integration process

NASA Astrophysics Data System (ADS)

Zhang, Ning-ning; Zhou, Chang-chun; Cong, Long-fei; Cao, Wen-long; Zhou, You

2016-01-01

The cyclonic-static micro-bubble flotation column (FCSMC) is a highly efficient mineral processing equipment. In this study, a cell-column (FCSMC) integration process was investigated for the separation of bauxite and its feasibility was analyzed on a theoretical basis. The properties of low-grade bauxite ore from Henan Province, China were analyzed. Parameters such as reagent dosage, scraping bubble time, and pressure of the circulating pump during the sorting process were investigated and optimized to improve the flotation efficiency. On the basis of these parameters, continuous separation experiments were conducted. Bauxite concentrate with an aluminum-to-silicon (A/S) mass ratio of 6.37 and a 77.63wt% recovery rate were achieved via a flow sheet consisting of "fast flotation using a flotation cell, one roughing flotation and one cleaning flotation using flotation columns". Compared with the full-flotation-cells process, the cell-column integration process resulted in an increase of the A/S ratio by 0.41 and the recovery rate by 17.58wt%. Cell-column integration separation technology represents a new approach for the separation of middle-to-low-grade bauxite ore.

Facile Separation of 5-O-Galloylquinic Acid from Chinese Green Tea Extract using Mesoporous Zirconium Phosphate.

PubMed

Ma, Yilong; Shang, Yafang; Zhu, Danye; Wang, Caihong; Zhong, Zhifeng; Xu, Ziyang

2016-05-01

5-O-Galloylquinic acid from green tea and other plants is attracting increasing attention for its antioxidant and antileishmanial bioactivities. It is always isolated using a silica column, a Sephadex column and high-performance liquid chromatography (HPLC) methods, which are either laborious or instrument dependent. To develop a new method to easily separate 5-O-galloylquinic acid. Mesoporous zirconium phosphate (m-ZrP) was prepared to conveniently separate 5-O-galloylquinic acid from Chinese green tea extract, and the target compound was easily obtained by simple steps of adsorption, washing and desorption. The effects of the green tea extraction conditions, extract concentrations, and m-ZrP adsorption/desorption dynamics on the 5-O-galloylquinic acid separation were evaluated. 5-O-Galloylquinic acid that was separated from a 70% ethanol extract of green tea was of moderate HPLC purity (92%) and recovery (88%), and an increased non-specific binding of epigallocatechin gallate (EGCG) on m-ZrP was observed in the diluted tea extract. The times for maximal adsorption of 5-O-galloylquinic acid in 70% ethanol extract and maximal desorption of 5-O-galloylquinic acid in 0.4% phosphoric acid solution were confirmed as 7 h and 5 h, respectively. A facile method to separate 5-O-galloylquinic acid from Chinese green tea extract using m-ZrP was established. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Rapid determination of caffeoylquinic acid derivatives in Cynara scolymus L. by ultra-fast liquid chromatography/tandem mass spectrometry based on a fused core C18 column.

PubMed

Shen, Qing; Dai, Zhiyuan; Lu, Yanbin

2010-10-01

An ultra-fast high-performance LC-ESI-MS/MS method was developed for the analysis and quantification of caffeoylquinic acid derivatives, including chlorogenic acid, 1,3-di-O-caffeoylquinic acid (cynarin) and 1,5-di-O-caffeoylquinic acid, in artichoke (Cynara scolymus L.) heads and leaves. The rapid separation (less than 4  min) was achieved based on a Halo fused core C18-silica column (50  mm × 2.1  mm id, 2.7  μm). The target compounds were detected and quantified by a triple-quadrupole mass spectrometer in multiple-reaction monitoring mode. The calibration function is linear from 0.06 to 2800  ng/mL for chlorogenic acid, 0.3-3000  ng/mL for cynarin and 0.24-4800  ng/mL for 1,5-di-O-caffeoylquinic acid, respectively. The average recoveries ranged from 92.1 to 113.2% with RSDs ≤6.5%. Moreover, four batches of artichoke head and leaf extracts were analyzed using the established method. The results indicated that the Halo fused core column provided much faster separations and higher sample throughput without sacrificing column ruggedness and reliability, and triple-quadrupole MS provided extraordinarily lower LOQs for most of the target analytes. Comparing to conventional quantitative approaches, the established method was fast, sensitive and reliable for the determination of caffeoylquinic acid derivatives in artichoke.

Chromatographic Separation, and Characteristics of Nucleic Acids from HeLa Cells

PubMed Central

Philipson, Lennart

1961-01-01

The application of the phenol-duponol method to extraction of nucleic acids from HeLa cells is described. Chromatography of the phenol extract on an esterified bovine serum albumin column with a salt gradient of sodium chloride gives separation of soluble RNA, DNA, and two different high molecular RNA fractions. Ultracentrifugation of the DNA eluted from the column gives a sedimentation coefficient (s 20 o,w) of 38, which agrees with ultracentrifugation data on the phenol extract. The eluted RNA appears polydisperse at low ionic strength, but at high ionic strength and after alcohol precipitation two fractions with the sedimentation coefficients of 16 and 25 to 29, respectively, were obtained. PMID:13735276

Simple determination of betaine, l-carnitine and choline in human urine using self-packed column and column-switching ion chromatography with nonsuppressed conductivity detection.

PubMed

Wei, Dan; Zhu, Yan; Guo, Ming

2018-02-01

A sequential online extraction, clean-up and separation system for the determination of betaine, l-carnitine and choline in human urine using column-switching ion chromatography with nonsuppressed conductivity detection was developed in this work. A self-packed pretreatment column (50 × 4.6 mm, i.d.) was used for the extraction and clean-up of betaine, l-carnitine and choline. The separation was achieved using self-packed cationic exchange column (150 × 4.6 mm, i.d.), followed by nonsuppressed conductivity detection. Under optimized experimental conditions, the developed method presented good analytical performance, with excellent linearity in the range of 0.60-100 μg mL -1 for betaine, 0.75-100 μg mL -1 for l-carnitine and 0.50-100 μg mL -1 for choline, with all correlation coefficients (R 2 ) >0.99 in urine. The limits of detection were 0.15 μg mL -1 for betaine, 0.20 μg mL -1 for l-carnitine and 0.09 μg mL -1 for choline. The intra- and inter-day accuracy and precision for all quality controls were within ±10.32 and ±9.05%, respectively. Satisfactory recovery was observed between 92.8 and 102.0%. The validated method was successfully applied to the detection of urinary samples from 10 healthy people. The values detected in human urine using the proposed method showed good agreement with the measurement reported previously. Copyright © 2017 John Wiley & Sons, Ltd.

A NEW HPLC METHOD FOR SEPARATION OF PHYTOPLANKTON PIGMENTS IN NATURAL SAMPLES

EPA Science Inventory

A new high-performance liquid chromatographic (HPLC) method was developed to analyze, in a single run, most polar and non-polar chlorophylls and carotenoids from marine phytoplankton. The method is based on a reverse-phase amide C16 (RP-amide C16) column and an elution gradient o...

Determination of strontium-90 in deer bones by liquid scintillation spectrometry after separation on Sr-specific ion exchange columns.

PubMed

Landstetter, Claudia; Wallner, Gabriele

2006-01-01

The activity concentration of (90)Sr was determined in several deer bones from Austria. Strontium specific ion exchange columns with 4',4''(5'')-di-t-butylcyclohexane-18-crown-6 from Eichrom Industries, Inc. were used for separation. The yield of the chemical procedure was quantified with AAS. Directly after column separation, the solution containing (90)Sr was mixed with the scintillation cocktail HiSafe III and measured by liquid scintillation counting. Prevention of (210)Pb contamination and reusability of the separation columns was investigated as well as the activity distribution within the bones. Results were compared with pre-Chernobyl measurements in Austria; a correlation between activity concentration of (90)Sr and site altitude was found.

Construction of a hydrazone-linked chiral covalent organic framework-silica composite as the stationary phase for high performance liquid chromatography.

PubMed

Zhang, Kai; Cai, Song-Liang; Yan, Yi-Lun; He, Zi-Hao; Lin, Hui-Mei; Huang, Xiao-Ling; Zheng, Sheng-Run; Fan, Jun; Zhang, Wei-Guang

2017-10-13

Covalent organic frameworks (COFs), as an emerging class of crystalline porous organic polymers, have great potential for applications in chromatographic separation owning to their fascinating crystalline structures and outstanding properties. However, development of COF materials as novel stationary phases in high performance liquid chromatography (HPLC) is just in its infancy. Herein, we report the design and construction of a new hydrazone-linked chiral COF, termed BtaMth COF, from a chiral hydrazide building block (Mth) and present a one-pot synthetic method for the fabrication of BtaMth@SiO 2 composite for HPLC separation of isomers. The as-synthesized BtaMth chiral COF displays good crystallinity, high porosity, as well as excellent chemical stability. Meanwhile, the fabricated HPLC column by using BtaMth@SiO 2 composite as the new stationary phase exhibits high resolution performances for the separation of positional isomers including nitrotoluene and nitrochlorobenzene, as well as cis-trans isomers including beta-cypermethrin and metconazole. Additionally, some effects such as the composition of the mobile phase and column temperature for HPLC separations on the BtaMth@SiO 2 packed column also have been studied in detail. The successful applications indicate the great potentials of hydrazone-linked chiral COF-silica composite as novel stationary phase for the efficient HPLC separation. Copyright © 2017 Elsevier B.V. All rights reserved.

Method for the concentration and separation of actinides from biological and environmental samples

DOEpatents

Horwitz, E. Philip; Dietz, Mark L.

1989-01-01

A method and apparatus for the quantitative recover of actinide values from biological and environmental sample by passing appropriately prepared samples in a mineral acid solution through a separation column of a dialkyl(phenyl)-N,N-dialylcarbamoylmethylphosphine oxide dissolved in tri-n-butyl phosphate on an inert substrate which selectively extracts the actinide values. The actinide values can be eluted either as a group or individually and their presence quantitatively detected by alpha counting.

Quantitation of promethazine and metabolites in urine samples using on-line solid-phase extraction and column-switching

NASA Technical Reports Server (NTRS)

Song, Q.; Putcha, L.; Harm, D. L. (Principal Investigator)

2001-01-01

A chromatographic method for the quantitation of promethazine (PMZ) and its three metabolites in urine employing on-line solid-phase extraction and column-switching has been developed. The column-switching system described here uses an extraction column for the purification of PMZ and its metabolites from a urine matrix. The extraneous matrix interference was removed by flushing the extraction column with a gradient elution. The analytes of interest were then eluted onto an analytical column for further chromatographic separation using a mobile phase of greater solvent strength. This method is specific and sensitive with a range of 3.75-1400 ng/ml for PMZ and 2.5-1400 ng/ml for the metabolites promethazine sulfoxide, monodesmethyl promethazine sulfoxide and monodesmethyl promethazine. The lower limits of quantitation (LLOQ) were 3.75 ng/ml with less than 6.2% C.V. for PMZ and 2.50 ng/ml with less than 11.5% C.V. for metabolites based on a signal-to-noise ratio of 10:1 or greater. The accuracy and precision were within +/- 11.8% in bias and not greater than 5.5% C.V. in intra- and inter-assay precision for PMZ and metabolites. Method robustness was investigated using a Plackett-Burman experimental design. The applicability of the analytical method for pharmacokinetic studies in humans is illustrated.

Quality by design approach for the separation of naproxcinod and its related substances by fused core particle technology column.

PubMed

Inugala, Ugandar Reddy; Pothuraju, Nageswara Rao; Vangala, Ranga Reddy

2013-01-01

This paper describes the development of a rapid, novel, stability-indicating gradient reversed-phase high-performance liquid chromatographic method and associated system suitability parameters for the analysis of naproxcinod in the presence of its related substances and degradents using a quality-by-design approach. All of the factors that affect the separation of naproxcinod and its impurities and their mutual interactions were investigated and robustness of the method was ensured. The method was developed using an Ascentis Express C8 150 × 4.6 mm, 2.7 µm column with a mobile phase containing a gradient mixture of two solvents. The eluted compounds were monitored at 230 nm, the run time was 20 min within which naproxcinod and its eight impurities were satisfactorily separated. Naproxcinod was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Naproxcinod was found to degrade significantly in acidic and basic conditions and to be stable in thermal, photolytic, oxidative and aqueous degradation conditions. The degradation products were satisfactorily resolved from the primary peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness.

Capillary trap column with strong cation-exchange monolith for automated shotgun proteome analysis.

PubMed

Wang, Fangjun; Dong, Jing; Jiang, Xiaogang; Ye, Mingliang; Zou, Hanfa

2007-09-01

A 150 microm internal diameter capillary monolithic column with a strong cation-exchange stationary phase was prepared by direct in situ polymerization of ethylene glycol methacrylate phosphate and bisacrylamide in a trinary porogenic solvent consisting dimethylsulfoxide, dodecanol, and N,N'-dimethylformamide. This phosphate monolithic column exhibits higher dynamic binding capacity, faster kinetic adsorption of peptides, and more than 10 times higher permeability than the column packed with commercially available strong cation-exchange particles. It was applied as a trap column in a nanoflow liquid chromatography-tandem mass spectrometry system for automated sample injection and online multidimensional separation. It was observed that the sample could be loaded at a flow rate as high as 40 microL/min with a back pressure of approximately 1300 psi and without compromising the separation efficiency. Because of its good orthogonality to the reversed phase separation mechanism, the phosphate monolithic trap column was coupled with a reversed-phase column for online multidimensional separation of 19 microg of the tryptic digest of yeast proteins. A total of 1522 distinct proteins were identified from 5608 unique peptides (total of 54,780 peptides) at the false positive rate only 0.46%.

Short-cut Methods versus Rigorous Methods for Performance-evaluation of Distillation Configurations

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

Ramapriya, Gautham Madenoor; Selvarajah, Ajiththaa; Jimenez Cucaita, Luis Eduardo

Here, this study demonstrates the efficacy of a short-cut method such as the Global Minimization Algorithm (GMA), that uses assumptions of ideal mixtures, constant molar overflow (CMO) and pinched columns, in pruning the search-space of distillation column configurations for zeotropic multicomponent separation, to provide a small subset of attractive configurations with low minimum heat duties. The short-cut method, due to its simplifying assumptions, is computationally efficient, yet reliable in identifying the small subset of useful configurations for further detailed process evaluation. This two-tier approach allows expedient search of the configuration space containing hundreds to thousands of candidate configurations for amore » given application.« less

Short-cut Methods versus Rigorous Methods for Performance-evaluation of Distillation Configurations

DOE PAGES

Ramapriya, Gautham Madenoor; Selvarajah, Ajiththaa; Jimenez Cucaita, Luis Eduardo; ...

2018-05-17

Here, this study demonstrates the efficacy of a short-cut method such as the Global Minimization Algorithm (GMA), that uses assumptions of ideal mixtures, constant molar overflow (CMO) and pinched columns, in pruning the search-space of distillation column configurations for zeotropic multicomponent separation, to provide a small subset of attractive configurations with low minimum heat duties. The short-cut method, due to its simplifying assumptions, is computationally efficient, yet reliable in identifying the small subset of useful configurations for further detailed process evaluation. This two-tier approach allows expedient search of the configuration space containing hundreds to thousands of candidate configurations for amore » given application.« less

Rapid chiral separation of atenolol, metoprolol, propranolol and the zwitterionic metoprolol acid using supercritical fluid chromatography-tandem mass spectrometry - Application to wetland microcosms.

PubMed

Svan, Alfred; Hedeland, Mikael; Arvidsson, Torbjörn; Jasper, Justin T; Sedlak, David L; Pettersson, Curt E

2015-08-28

A method for enantiomeric separation of the three β-blocking agents atenolol, metoprolol, propranolol and the zwitterionic metoprolol acid, a major metabolite of both metoprolol and in environmental matrices also atenolol, has been developed. By use of supercritical fluid chromatography and the polysaccharide-based Chiralpak(®) IB-3, all four compounds were simultaneously enantiomerically separated (Rs>1.5) within 8min. Detection was performed using tandem mass spectrometry, and to avoid isobaric interference between the co-eluting metoprolol and metoprolol acid, the achiral column Acquity(®) UPC(2) BEH 2-EP was attached ahead of to the chiral column. Carbon dioxide with 18% methanol containing 0.5% (v/v) of the additives trifluoroacetic acid and ammonia in a 2:1 molar ratio were used as mobile phase. A post column make-up flow (0.3mL/min) of methanol containing 0.1% (v/v) formic acid was used to enhance the positive electrospray ionization. Detection was carried out using a triple quadrupole mass spectrometer operating in the selected reaction monitoring mode, using one transition per analyte and internal standard. The method was successfully applied for monitoring the enantiomeric fraction change over time in a laboratory scale wetland degradation study. It showed good precision, recovery, sensitivity and low effect of the sample matrix. Copyright © 2015. Published by Elsevier B.V.

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

PubMed

Liu, Yong-Qiang; Yu, Hong

2017-04-01

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg 2+ , Ca 2+ , and Sr 2+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg 2+ , Ca 2+ , and Sr 2+ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg 2+ , Ca 2+ , and Sr 2+ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isotopic separation of acetaldehyde and methanol from their deuterated isotopologues on a porous layer open tubular column allows quantification by stable isotope dilution without mass spectrometric detection.

PubMed

Schmarr, Hans-Georg; Wacker, Michael; Mathes, Maximilian

2017-01-20

An isotopic separation of acetaldehyde and acetaldehyde-2,2,2-d3 was achieved in a temperature programmed run on a porous layer open tubular (PLOT) capillary column coated with particles of divinylbenzene ethylene glycol/dimethylacrylate (Rt ® -U-BOND). This is the prerequisite for the development of quantitative analytical methods based on a stable isotope dilution assay (SIDA) without a mass spectrometric detection (non-MS SIDA). For routine analysis a flame ionization detector (FID) can thus be applied as a robust and low-cost alternative. In a preliminary study, static headspace extraction and gas chromatographic separation (HS-GC-FID) of acetaldehyde in aqueous solutions was shown as an application. Good linearity was obtained in a calibration range from 0.4 to 40mgL -1 , with peak integration benefitting from the inverse isotope effect encountered on the specific porous polymer. Furthermore, separation of methanol and deuterated methanol (d3) could also be achieved under the same chromatographic conditions. The achieved isotopic separation of these important volatile compounds now allows non-MS SIDA-based methods that are still to be developed. Copyright © 2016 Elsevier B.V. All rights reserved.

A novel approach to the simultaneous extraction and non-targeted analysis of the small molecules metabolome and lipidome using 96-well solid phase extraction plates with column-switching technology.

PubMed

Li, Yubo; Zhang, Zhenzhu; Liu, Xinyu; Li, Aizhu; Hou, Zhiguo; Wang, Yuming; Zhang, Yanjun

2015-08-28

This study combines solid phase extraction (SPE) using 96-well plates with column-switching technology to construct a rapid and high-throughput method for the simultaneous extraction and non-targeted analysis of small molecules metabolome and lipidome based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry. This study first investigated the columns and analytical conditions for small molecules metabolome and lipidome, separated by an HSS T3 and BEH C18 columns, respectively. Next, the loading capacity and actuation duration of SPE were further optimized. Subsequently, SPE and column switching were used together to rapidly and comprehensively analyze the biological samples. The experimental results showed that the new analytical procedure had good precision and maintained sample stability (RSD<15%). The method was then satisfactorily applied to more widely analyze the small molecules metabolome and lipidome to test the throughput. The resulting method represents a new analytical approach for biological samples, and a highly useful tool for researches in metabolomics and lipidomics. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of volatile compounds in cider apple juices using a covalently bonded ionic liquid coating as the stationary phase in gas chromatography.

PubMed

Pello-Palma, Jairo; González-Álvarez, Jaime; Gutiérrez-Álvarez, María Dolores; Dapena de la Fuente, Enrique; Mangas-Alonso, Juan José; Méndez-Sánchez, Daniel; Gotor-Fernández, Vicente; Arias-Abrodo, Pilar

2017-04-01

A chromatographic method for the separation of volatile compounds in Asturian cider apple juices has been developed. For this separation purpose, a monocationic imidazolium-based ionic liquid bearing a reactive terminal iodine atom was synthesized by a quaternization-anion exchange chemical sequence. Next, the gas chromatography (GC) stationary phase was prepared by covalently linking the imidazolium monolith to the reactive silanol groups of the inner capillary wall at 70 °C. This coated GC column exhibited good thermal stability (290 °C), as well as good efficiency (2000 plates/m) in the separation of volatile compounds from Asturian apple cider juices, and was characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the chromatographic method was evaluated, obtaining relative standard deviations from 3.7 to 12.9% and from 7.4 to 18.0%, respectively. Furthermore, recoveries from 82.5 to 122% were achieved. Graphical Abstract Covalent bonding of an ionic liquid to inner column wall led to a great improvement of the separation efficiencies of stationary phases in gas chromatography.

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

PubMed

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

2012-11-02

A methodology based on on-line coupling of size exclusion chromatography (SEC) with mixed-mode liquid chromatography (LC) has been developed. The method allows for simultaneous measurement of a wide range of components in biopharmaceutical drug products. These components include the active pharmaceutical ingredient (protein) and various kinds of excipients such as cations, anions, nonionic hydrophobic surfactant and hydrophilic sugars. Dual short SEC columns are used to separate small molecule excipients from large protein molecules. The separated protein is quantified using a UV detector at 280 nm. The isolated excipients are switched, online, to the Trinity P1 mixed-mode column for separation, and detected by an evaporative light scattering detector (ELSD). Using a stationary phase with 1.7 μm particles in SEC allows for the use of volatile buffers for both SEC and mix-mode separation. This facilitates the detection of different excipients by ELSD and provides potential for online characterization of the protein with mass spectrometry (MS). The method has been applied to quantitate protein and excipients in different biopharmaceutical drug products including monoclonal antibodies (mAb), antibody drug conjugates (ADC) and vaccines. Copyright © 2012 Elsevier B.V. All rights reserved.

Liquid chromatography of polymers under limiting conditions of desorption II. Tandem injection and quantitative molar mass determination.

PubMed

Snauko, Marián; Berek, Dusan

2005-11-11

Liquid chromatography under limiting conditions of desorption (LC LCD) is a method which allows molar mass independent elution of various synthetic polymers. A narrow, slowly moving zone of small molecules, which promotes full adsorption of one kind of polymer species within column (an adsorli) acts as an impermeable barrier for the fast moving macromolecules. The latter accumulate on the barrier edge and elute nearly in total volume of liquid within column. At the same time, transport of less adsorptive macromolecules is not hampered so that these are eluted in the size exclusion (SEC) mode. As result, polymers differing in their polarity and adsorptivity can be easily separated without molar mass interference. Three methods of barrier creation are discussed and compared. It is shown that a fraction of sample may elute unretained if the adsorli sample solvent is used as a barrier in connection with a narrow-pore column packing. One part of excluded macromolecules likely breaks-out from the adsorli zone and this results in partial loss of sample and distortion of the LC LCD peaks. This problem can be avoided if the adsorli zone is injected immediately before sample solution. Applicability of the LC LCD method for polymer separation has been demonstrated with a model mixture of poly(methyl methacrylate) (adsorbing polymer) and polystyrene (non adsorbing polymer) using bare silica gel as a column packing with a combination of tetrahydrofuran (a desorption promoting liquid -a desorli) and toluene (adsorli). It has been shown that the LC LCD procedure with tandem injection allows simple and fast discrimination of polymer blend components with good repeatability and high sample recovery. For quantitative determination of molar masses of both LC LCD and SEC eluted polymers, an additional size exclusion chromatographic column can be applied either in a conventional way or in combination with a multi-angle light scattering detector. A single eluent is used in the latter column, which separates the mixed mobile phase, system peaks and the desorli zone from the polymer peaks so that measurements are free from disturbances caused by the changing eluent composition. The resulting LC LCD x SEC procedure has been successfully applied to poly(methyl methacrylate) samples.

Controlled irrigation of a structured packing as a method for increasing the efficiency of liquid mixture separation in the distillation column

NASA Astrophysics Data System (ADS)

Pavlenko, A. N.; Zhukov, V. E.; Pecherkin, N. I.; Nazarov, A. D.; Li, X.; Li, H.; Gao, X.; Sui, H.

2017-09-01

The use of modern structured packing in the distillation columns allows much more even distribution of the liquid film over the packing surface, but it does not completely solve the problem of uniform distribution of flow parameters over the entire height of the packing. Negative stratification of vapor along the packing height caused by different densities of vapor mixture components and higher temperature in the lower part of the column leads to formation of large-scale maldistributions of temperature and mixture composition over the column cross-section even under the conditions of uniform irrigation of packing with liquid. In these experiments, the idea of compensatory action of liquid distributor on the large-scale maldistribution of mixture composition over the column cross-section was implemented. The experiments were carried out in the distillation column with the diameter of 0.9 m on 10 layers of the Mellapak 350Y packing with the total height of 2.1 m. The mixture of R-21 and R-114 was used as the working mixture. To irrigate the packing, the liquid distributorr with 126 independently controlled solenoid valves overlapping the holes with the diameter of 5 mm, specially designed by the authors, was used. Response of the column to the action of liquid distributor was observed in real time according to the indications of 3 groups of thermometers mounted in 3 different cross-sections of the column. The experiments showed that the minimal correction of the drip point pattern in the controlled liquid distributor can significantly affect the pattern of flow parameter distribution over the cross-section and height of the mass transfer surface and increase separation efficiency of the column within 20%.

Preparation and evaluation of silica-UIO-66 composite as liquid chromatographic stationary phase for fast and efficient separation.

PubMed

Yan, Zhiming; Zheng, Jiangnan; Chen, Jinfeng; Tong, Ping; Lu, Minghua; Lin, Zian; Zhang, Lan

2014-10-31

A silica-UIO-66 composite was fabricated by a simple hydrothermal method and then applied as liquid chromatographic stationary phase for fast and efficient separation. X-ray diffraction patterns showed the presence of UIO-66 crystals in the silica-UIO-66 composites; while scanning electron microscope (SEM) images revealed that silica-UIO-66 composites were a homogeneous mixture of silica bead and UIO-66 crystals. A variety of substituted aromatics, chlorobenzene compounds and polycyclic aromatic hydrocarbons (PAHs) were used to evaluate the retention properties of the silica-UIO-66 composite packed column. Under the optimized conditions, baseline separation of ethylbenzene (EB) and styrene was obtained with high resolution and short retention time. In addition, the silica-UIO-66 composite packed column also showed some advantages in separation of positional isomers, with which baseline separation of EB and xylene, chlorotoluene and dichlorobenzene isomers was achieved. Moreover, the retention mechanisms of these compounds were also discussed in detail. The relative standard deviations (RSDs) for the separation of EB and xylene, chlorotoluene and dichlorobenzene isomers, as well as EB and styrene were 0.42-0.9%, 1.0-1.9%, 0.75-2.0%, and 0.9-2.1% for the retention time, peak area, peak height, and half peak width, respectively. The column efficiencies for EB, p-chlorotoluene, p-dichlorobenzene and styrene were 8780, 9060, 9990 and 5130 plates/m. The successful applications suggested high potentials of silica-MOFs composite as stationary phase for fast and efficient liquid chromatography separation. Copyright © 2014 Elsevier B.V. All rights reserved.

Isolation of Three Components from Spearmint Oil: An Exercise in Column and Thin-Layer Chromatography

ERIC Educational Resources Information Center

Davies, Don R.; Johnson, Todd M.

2007-01-01

A simple experiment for undergraduate organic chemistry students to separate a colorless mixture using column chromatography and then monitor the outcome of the separation using thin-layer chromatography (TLC) and infrared spectroscopy(IR) is described. The experiment teaches students the principle and techniques of column and thin-layer…

Colorful Column Chromatography: A Classroom Demonstration of a Three-Component Separation

ERIC Educational Resources Information Center

Heumann, Lars V.

2008-01-01

A classroom demonstration detailing the procedure for the separation of a ternary mixture consisting of intensely colored compounds using silica gel column chromatography is described. The audience can follow the compounds during their passage through the column as individual, colored bands while learning about different tools and techniques used…

Development of a slicing device for Apollo-Soyuz Test Project (ASTP) electrophoresis technology experiment MA-011

NASA Technical Reports Server (NTRS)

Nerren, B. H.

1977-01-01

The electrophoresis of six columns was accomplished on the Apollo-Soyuz test Project. After separation, these columns were frozen in orbit and were returned for ground-based analyses. One major goal of the MA-011 experiment was the assessment of the separation achieved in orbit by slicing these frozen columns. The slicing of the frozen columns required a new device. The development of that device is described.

Effect of Non-laminar Regime on the Efficiency of a Thermal Diffusion Column. Report No. 26; INFLUENCIA DEL REGIMEN NO LAMINAR SOBRE LA EFICIENCIA DE UNA COLUMNA DE DIFUSION TERMICA. Informe No. 26

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

Espanol, C.E.

1960-01-01

The effect of the appearance of localized perturbations on the separation factor and operation time of a thermal diffusion column is studied. The separation factor of a column was obtained experimentally and the enrichment was recorded continuously as a function of time by measurement of the thermal conductivity of the gaseous mixture at the foot and head of the column. A mixture of Ar and CO/sub 2/ was used as it behaves as an isotopic mixture. The results showed the linear decrease of the separation factor with the number of stages and the operation time practically does not vary. Themore » introduction of localized turbulences in a thermal diffusion column reduces the column yield. (J.S.R.)« less

Long-chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion-exchange chromatography.

PubMed

Qiu, Hongdeng; Zhang, Qinghua; Chen, Limei; Liu, Xia; Jiang, Shengxiang

2008-08-01

Separations of common inorganic anions were carried out on ODS columns coated with two long-chain alkylimidazolium ionic liquids ([C(12)MIm]Br and [C(14)MIm]Br) as new cationic surfactants for ion chromatography. With phthalate buffer solution as the mobile phases and non-suppressed conductivity detection, high column efficiencies and excellent selectivity were obtained in the separation of inorganic anions. Chromatographic parameters are calculated and the results show that the coated column possesses significant potential for the analysis of some inorganic anions such as CH(3)COO(-), IO(3)(-), Cl(-), BrO(3)(-), NO(2)(-), Br(-), NO(3)(-), SO(4)(2-), I(-), BF(4)(-), and SCN(-). The effect of eluent pH values on the separation of anions has been studied on the column coated with [C(12)MIm]Br. The stability of the coated columns was also examined.

Separative analyses of a chromatographic column packed with a core-shell adsorbent for lithium isotope separation

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

Sugiyama, T.; Sugura, K.; Enokida, Y.

2015-03-15

Lithium-6 is used as a blanket material for sufficient tritium production in DT fueled fusion reactors. A core-shell type adsorbent was proposed for lithium isotope separation by chromatography. The mass transfer model in a chromatographic column consisted of 4 steps, such as convection and dispersion in the column, transfer through liquid films, intra-particle diffusion and and adsorption or desorption at the local adsorption sites. A model was developed and concentration profiles and time variation in the column were numerically simulated. It became clear that core-shell type adsorbents with thin porous shell were saturated rapidly relatively to fully porous one andmore » established a sharp edge of adsorption band. This is very important feature because lithium isotope separation requires long-distance development of adsorption band. The values of HETP (Height Equivalent of a Theoretical Plate) for core-shell adsorbent packed column were estimated by statistical moments of the step response curve. The value of HETP decreased with the thickness of the porous shell. A core-shell type adsorbent is, then, useful for lithium isotope separation. (authors)« less

Microfluidic chip for peptide analysis with an integrated HPLC column, sample enrichment column, and nanoelectrospray tip.

PubMed

Yin, Hongfeng; Killeen, Kevin; Brennen, Reid; Sobek, Dan; Werlich, Mark; van de Goor, Tom

2005-01-15

Current nano-LC/MS systems require the use of an enrichment column, a separation column, a nanospray tip, and the fittings needed to connect these parts together. In this paper, we present a microfabricated approach to nano-LC, which integrates these components on a single LC chip, eliminating the need for conventional LC connections. The chip was fabricated by laminating polyimide films with laser-ablated channels, ports, and frit structures. The enrichment and separation columns were packed using conventional reversed-phase chromatography particles. A face-seal rotary valve provided a means for switching between sample loading and separation configurations with minimum dead and delay volumes while allowing high-pressure operation. The LC chip and valve assembly were mounted within a custom electrospray source on an ion-trap mass spectrometer. The overall system performance was demonstrated through reversed-phase gradient separations of tryptic protein digests at flow rates between 100 and 400 nL/min. Microfluidic integration of the nano-LC components enabled separations with subfemtomole detection sensitivity, minimal carryover, and robust and stable electrospray throughout the LC solvent gradient.

A fine coal circuitry study using column flotation and gravity separation. Quarterly report, 1 March 1995--31 May 1995

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

Honaker, R.Q.; Reed, S.

1995-12-31

Column flotation provides excellent recovery of ultrafine coal while producing low ash content concentrates. However, column flotation is not efficient for treating fine coal containing significant amounts of mixed-phase particles. Fortunately, enhanced gravity separation has proved to have the ability to treat the mixed-phased particles more effectively. A disadvantage of gravity separation is that ultrafine clay particles are not easily rejected. Thus, a combination of these two technologies may provide a circuit that maximizes both the ash and sulfur rejection that can be achieved by physical coal cleaning while maintaining a high energy recovery. This project is studying the potentialmore » of using different combinations of gravity separators, i.e., a Floatex hydrosizer and a Falcon Concentrator, and a proven flotation column, which will be selected based on previous studies by the principle investigator. During this reporting period, an extensive separation performance comparison between a pilot-scale Floatex Density Separator (18{times}18-inch) and an existing spiral circuit has been conducted at Kerf-McGee Coal Preparation plan for the treatment of nominally {minus}16 mesh coal. The results indicate that the Floatex is a more efficient separation device (E{sub p}=0.12) than a conventional coal spiral (E{sub p}=0.18) for Illinois seam coals. In addition, the treatment of {minus}100 mesh Illinois No. 5 fine coal from the same plant using Falcon concentrator, column flotation (Packed-Column) and their different combinations was also evaluated. For a single operation, both Falcon concentrator and column flotation can produce a clean coal product with 90% combustible recovery and 5% ash content. In the case of the combined circuit, column flotation followed by the Falcon achieved a higher combustible recovery value (about 75%) than that obtained by the individual units while maintaining an ash content less than 3%.« less

[Method of component assay of alpha-glucosyltransferase-treated stevia (enzymatically modified stevia) products using enzymatic hydrolysis].

PubMed

Hirata, Keiko; Shimamura, Yasuhiro; Suzuki, Keiko; Sadamasu, Yuki; Ito, Koichi

2005-12-01

We have developed an analytical method for components of alpha-glucosyltransferase-treated stevia, a food additive product. Suitable conditions to separate additional sugar from alpha-glucosyltransferase-treated stevia by using glucoamylase were found (55 degrees C for 3 hr with 250 U of glucoamylase in 10 mL of reaction solution). By solid-phase extraction using a C18 cartridge column, polysaccharides were excluded from the sample, and the glycosides and sugar obtained after hydrolysis with glucoamylase were separated on another C18 cartridge column. The glycosides and sugar contents were determined by HPLC. By this method, additional sugar was detected in all of three product samples tested and the sugar was glucose. The contents of glucose and total glycosides (minus unreacted glycoside) were 25-42% and 35.7-52.5%, respectively. In alpha-glucosyltransferase-treated stevia, the sum of total glycosides and glucose amounted to 77.5-80.4% of the total and their recoveries from samples from which polysaccharide had been excluded by C18 cartridge column processing were over 85%. The contents of alpha-glucosyltransferase-treated stevia obtained by multiplying the sugar content by the coefficient (0.9) for hydrolysis and converting on dry weight basis were all over 80.0% and met the standard set by the Japan Food Additives Association.

Green approach using monolithic column for simultaneous determination of coformulated drugs.

PubMed

Yehia, Ali M; Mohamed, Heba M

2016-06-01

Green chemistry and sustainability is now entirely encompassed across the majority of pharmaceutical companies and research labs. Researchers' attention is careworn toward implementing the green analytical chemistry principles for more eco-friendly analytical methodologies. Solvents play a dominant role in determining the greenness of the analytical procedure. Using safer solvents, the greenness profile of the methodology could be increased remarkably. In this context, a green chromatographic method has been developed and validated for the simultaneous determination of phenylephrine, paracetamol, and guaifenesin in their ternary pharmaceutical mixture. The chromatographic separation was carried out using monolithic column and green solvents as mobile phase. The use of monolithic column allows efficient separation protocols at higher flow rates, which results in short time of analysis. Two-factor three-level experimental design was used to optimize the chromatographic conditions. The greenness profile of the proposed methodology was assessed using eco-scale as a green metrics and was found to be an excellent green method with regard to the usage and production of hazardous chemicals and solvents, energy consumption, and amount of produced waste. The proposed method improved the environmental impact without compromising the analytical performance criteria and could be used as a safer alternate for the routine analysis of the studied drugs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of alkenylbenzenes and related flavour compounds in food samples by on-column preconcentration-capillary liquid chromatography.

PubMed

Avila, Mónica; Zougagh, Mohammed; Escarpa, Alberto; Ríos, Angel

2009-10-23

A new, simple and versatile method is presented for the determination of different concentration levels of alkenylbenzenes (eugenol, isoeugenol, eugenol methyl ether, myristicin, anethole and estragole) and the related flavour compounds (coumarin and pulegone) in food samples. The method involves the use of a stationary phase (capillary column) for the enrichment with appropriate elution. After the sample had completely passed through the capillary column the eluent was changed and the separation/detection was achieved. Excellent linearity was obtained under the proposed conditions for a direct determination method and a method including on-line preconcentration. The limits of detection were in the ranges 97-148 and 9.5-14.2 ng/mL, respectively. Evidence for a matrix effect was not found and recoveries between 92 and 110% were obtained. The precision of the method, expressed as relative standard deviation values, was below 5% in all cases. The applicability of this methodology was tested by analyzing synthetic and real food samples.

Rapid and simple method for the determination of emodin in tartary buckwheat (Fagopyrum tataricum) by high-performance liquid chromatography coupled to a diode array detector.

PubMed

Peng, Lian-Xin; Wang, Jing-Bo; Hu, Li-Xue; Zhao, Jiang-Lin; Xiang, Da-Bing; Zou, Liang; Zhao, Gang

2013-01-30

A simple and rapid method for determining emodin, an active factor presented in tartary buckwheat (Fagopyrum tataricum), by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD) has been developed. Emodin was separated from an extract of buckwheat on a Kromasil-ODS C(18) (250 mm × 4.6 mm × 5 μm) column. The separation is achieved within 15 min on the ODS column. Emodin can be quantified using an external standard method detecting at 436 nm. Good linearity is obtained with a correlation coefficient exceeding 0.9992. The limit of detection and the limit of quantification are 5.7 and 19 μg/L, respectively. This method shows good reproducibility for the quantification of the emodin with a relative standard deviation value of 4.3%. Under optimized extraction conditions, the recovery of emodin was calculated as >90%. The validated method is successfully applied to quantify the emodin in tartary buckwheat and its products.

High Throughput Strontium Isotope Method for Monitoring Fluid Flow Related to Geological CO2 Storage

NASA Astrophysics Data System (ADS)

Capo, R. C.; Wall, A. J.; Stewart, B. W.; Phan, T. T.; Jain, J. C.; Hakala, J. A.; Guthrie, G. D.

2012-12-01

Natural isotope tracers, such as strontium (Sr), can be a unique and powerful component of a monitoring strategy at a CO2 storage site, facilitating both the quantification of reaction progress for fluid-rock interactions and the tracking of brine migration caused by CO2 injection. Several challenges must be overcome, however, to enable the routine use of isotopic tracers, including the ability to rapidly analyze numerous aqueous samples with potentially complex chemical compositions. In a field situation, it might be necessary to analyze tens of samples over a short period of time to identify subsurface reactions and respond to unexpected fluid movement in the host formation. These conditions require streamlined Sr separation chemistry for samples ranging from pristine groundwaters to those containing high total dissolved solids, followed by rapid measurement of isotope ratios with high analytical precision. We have optimized Sr separation chemistry and MC-ICP-MS methods to provide rapid and precise measurements of isotope ratios in geologic, hydrologic, and environmental samples. These improvements will allow an operator to independently prepare samples for Sr isotope analysis off-site using fast, low cost chemical separation procedures and commercially available components. Existing vacuum-assisted Sr separation procedures were modified by using inexpensive disposable parts to eliminate cross contamination. Experimental results indicate that the modified columns provide excellent separation of Sr from chemically complex samples and that Sr can be effectively isolated from problematic matrix elements (e.g., Ca, Ba, K) associated with oilfield brines and formation waters. The separation procedure is designed for high sample throughput in which batches of 24 samples can be processed in approximately 2 hours, and are ready for Sr isotope measurements by MC-ICP-MS immediately after collection from the columns. Precise Sr isotope results can be achieved by MC-ICP-MS with a throughput of 4 to 5 samples per hour. Our mean measured value of NIST Sr isotope standard SRM 987 is 0.710265 ± 0.000014 (2σ, n = 94). A range of brines and CO2-rich fluids analyzed by this method yielded results within the analytical uncertainty of 87Sr/86Sr ratios previously determined by standard column separation and thermal ionization mass spectrometry. This method provides a fast and effective way to use Sr isotopes for monitoring purposes related to geological CO2 storage.

Separation and purification of epigallocatechin-3-gallate (EGCG) from green tea using combined macroporous resin and polyamide column chromatography.

PubMed

Jin, Xin; Liu, Mingyan; Chen, Zaixing; Mao, Ruikun; Xiao, Qinghuan; Gao, Hua; Wei, Minjie

2015-10-01

Epigallocatechin-3-gallate (EGCG) is a major bioactive ingredient of green tea that produces beneficial neuroprotective effects. In this paper, to optimize the EGCG enrichment, thirteen macroporous resins with different chemical and physical properties were systemically evaluated. Among the thirteen tested resins, the H-bond resin HPD826 exhibited best adsorption/desorption capabilities and desorption ratio, as well as weakest affinity for caffeine. The absorption of EGCG on the HPD826 resin followed the pseudo-second-order kinetics and Langmuir isotherm model. The separation parameters of EGCG were optimized by dynamic adsorption/desorption experiments with the HPD826 resin column. Under the optimal condition, the content of EGCG in the 30% ethanol eluent increased by 5.8-fold from 7.7% to 44.6%, with the recovery yield of 72.1%. After further purification on a polyamide column, EGCG with 74.8% purity was obtained in the 40-50% ethanol fraction with a recovery rate of 88.4%. In addition, EGCG with 95.1% purity could be easily obtained after one-step crystallization in distilled water. Our study suggests that the combined macroporous resin and polyamide column chromatography is a simple method for large-scale separation and purification of EGCG from natural plants for food and pharmaceutical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Organic monolith frits encased in polyether ether ketone tubing with improved durability for liquid chromatography.

PubMed

Park, Sin Young; Cheong, Won Jo

2015-09-01

This study introduces a preparation method for polymer-encased monolith frits with improved durability for liquid chromatography columns. The inner surface of the polyether ether ketone tubing is pretreated with sulfuric acid in the presence of catalysts (vanadium oxide and sodium sulfate). The tubing was rinsed with water and acetone, flushed with nitrogen, and treated with glycidyl methacrylate. After washing, the monolith reaction mixture composed of lauryl methacrylate, ethylene glycol dimethacrylate, initiator, and porogenic solvent was filled in the tubing and subjected to in situ polymerization. The tubing was cut into thin slices and used as frits for microcolumns. To check their durability, the frit slices were placed in a vial and a heavy impact was applied on the vial by a vortex mixer for various periods. The frits made in the presence of catalysts were found to be more durable than those made without catalysts. Furthermore, when the monolith-incorporated tubing was used as a chromatography column, the column prepared in the presence of catalysts resulted in a better separation efficiency. The separation performance of the columns installed with the polyether ether ketone encased monolith frits was comparable to that of the columns installed with the commercial stainless-steel screen frits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anion-exchange high-performance liquid chromatography with post-column detection for the analysis of phytic acid and other inositol phosphates

NASA Technical Reports Server (NTRS)

Rounds, M. A.; Nielsen, S. S.; Mitchell, C. A. (Principal Investigator)

1993-01-01

The use of gradient anion-exchange HPLC, with a simple post-column detection system, is described for the separation of myo-inositol phosphates, including "phytic acid" (myo-inositol hexaphosphate). Hexa-, penta-, tetra-, tri- and diphosphate members of this homologous series are clearly resolved within 30 min. This method should facilitate analysis and quantitation of "phytic acid" and other inositol phosphates in plant, food, and soil samples.

Chromatographic peak deconvolution of constitutional isomers by multiple-reaction-monitoring mass spectrometry.

PubMed

Trapp, Oliver

2010-02-12

Highly efficient and sophisticated separation techniques are available to analyze complex compound mixtures with superior sensitivities and selectivities often enhanced by a 2nd dimension, e.g. a separation technique or spectroscopic and spectrometric techniques. For enantioselective separations numerous chiral stationary phases (CSPs) exist to cover a broad range of chiral compounds. Despite these advances enantioselective separations can become very challenging for mixtures of stereolabile constitutional isomers, because the on-column interconversion can lead to completely overlapping peak profiles. Typically, multidimensional separation techniques, e.g. multidimensional GC (MDGC), using an achiral 1st separation dimension and transferring selected analytes to a chiral 2nd separation are the method of choice to approach such problems. However, this procedure is very time consuming and only predefined sections of peaks can be transferred by column switching to the second dimension. Here we demonstrate for stereolabile 1,2-dialkylated diaziridines a technique to experimentally deconvolute overlapping gas chromatographic elution profiles of constitutional isomers based on multiple-reaction-monitoring MS (MRM-MS). The here presented technique takes advantage of different fragmentation probabilities and pathways to isolate the elution profile of configurational isomers. Copyright 2009 Elsevier B.V. All rights reserved.

[Determination of patulin in fruits and jam by solid phase extraction-ultra performance liquid chromatography].

PubMed

Lü, Weichao; Shen, Shuchang; Wang, Chao

2017-11-08

With magnesium silicate, silica gel, diatomite and calcium sulfate as raw materials, a new solid phase extraction column was prepared through a series of processes of grinding to ethanol homogenate, drying and packing into polypropylene tube. The sample was hydrolyzed by pectinase, extracted by acetonitrile and purified by solid phase extraction. The target compounds were separated on a C18 column (100 mm×2.1 mm, 1.8 μm), using 0.8% (v/v) tetrahydrofuran solution as mobile phase with a flow rate of 0.5 mL/min. The detection wavelength was 276 nm. The effect of pectinase on extraction yield and purification effect of solid-phase extraction column were investigated. The optimum chromatographic conditions were selected. There was a good linear relationship between the peak heights and the mass concentrations of patulin in the range of 0.1 to 10 mg/L with the correlation coefficient ( R 2 ) of 1. The limit of detection for this method was 10.22 μg/kg. The spiked recoveries of samples were 86.58%-94.84% with the relative standard deviations (RSDs) of 1.45%-2.28%. The results indicated that the self-made solid phase extraction column had a good purification efficiency, and the UPLC had a high separation efficiency. The method is simple, accurate and of great significance for the quality and safety control of fruit products.

In situ preparation of multilayer coated capillary column with HKUST-1 for separation of neutral small organic molecules by open tubular capillary electrochromatography.

PubMed

Xu, Yin-Yin; Lv, Wen-Juan; Ren, Cui-Ling; Niu, Xiao-Ying; Chen, Hong-Li; Chen, Xing-Guo

2018-01-12

The popularity of novel nanoparticles coated capillary column has aroused widespread attention of researchers. Metal organic frameworks (MOFs) with special structure and chemical properties have received great interest in separation sciences. This work presents the investigation of HKUST-1 (Hong Kong University of Science and Technology-1, called Cu 3 (BTC) 2 or MOF-199) nanoparticles as a new type of coating material for capillary electrochromatography. For the first time, three layers coating (3-LC), five layers coating (5-LC), ten layers coating (10-LC), fifteen layers coating (15-LC), twenty layers coating(20-LC) and twenty-five layers coating (25-LC) capillary columns coated with HKUST-1 nanoparticles were synthesized by covalent bond with in situ, layer-by-layer self-assembly approach. The results of scanning electron microscopy (SEM), X-ray diffraction (XRD) and plasma atomic emission spectrometry (ICP-AES) indicated that HKUST-1 was successfully grafted on the inner wall of the capillary. The separating performances of 3-LC, 5-LC, 10-LC, 15-LC, 20-LC and 25-LC open tubular (OT) capillary columns were studied with some neutral small organic molecules. The results indicated that the neutral small organic molecules were separated successfully with 10-LC, 15-LC and 20-LC OT capillary columns because of the size selectivity of lattice aperture and hydrophobicity of organic ligands. In addition, 10-LC and 15-LC OT capillary columns showed better performance for the separation of certain phenolic compounds. Furthermore, 10-LC, 15-LC and 20-LC OT capillary columns exhibited good intra-day repeatability with the relative standard deviations (RSDs; %) of migration time and peak areas lying in the range of 0.3-1.2% and 0.5-4.2%, respectively. For inter-day reproducibility, the RSDs of the three OT capillary columns were found to be lying in the range of 0.3-5.5% and 0.3-4.5% for migration time and peak area, respectively. The RSDs of retention times for column-to-column for three batches of 10-LC, 15-LC and 20-LC OT capillary columns were in the range from 2.3% to 7.2%. Moreover, the fabricated 10-LC, 15-LC and 20-LC OT capillary columns exhibited good repeatability and stability for separation, which could be used successively for more than 120 runs with no observable changes on the separation efficiency. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Read, Douglas; Sillerud, Colin Halliday

The overarching goal of this project is to integrate Sandia's microfabricated gas-chromatography ( GC) columns with a stationary phase material that is capable of retaining high-volatility chemicals and permanent gases. The successful integration of such a material with GCs would dramatically expand the repertoire of detectable compounds for Sandia's various microanalysis systems. One such promising class of candidate materials is metal-organic frameworks (MOFs). In this report we detail our methods for controlled deposition of HKUST-1 MOF stationary phases within GC columns. We demonstrate: the chromatographic separation of natural gas; a method for determining MOF film thickness from chromatography alone; andmore » the first-reported GC x GC separation of natural gas -- in general -- let alone for two disparate MOF stationary phases. In addition we determine the fundamental thermodynamic constant for mass sorption, the partition coefficient, for HKUST-1 and several light hydrocarbons and select toxic industrial chemicals.« less

Efficient extraction and preparative separation of four main isoflavonoids from Dalbergia odorifera T. Chen leaves by deep eutectic solvents-based negative pressure cavitation extraction followed by macroporous resin column chromatography.

PubMed

Li, Lu; Liu, Ju-Zhao; Luo, Meng; Wang, Wei; Huang, Yu-Yan; Efferth, Thomas; Wang, Hui-Mei; Fu, Yu-Jie

2016-10-15

In this study, green and efficient deep eutectic solvent-based negative pressure cavitation-assisted extraction (DES-NPCE) followed by macroporous resin column chromatography was developed to extract and separate four main isoflavonoids, i.e. prunetin, tectorigenin, genistein and biochanin A from Dalbergia odorifera T. Chen leaves. The extraction procedure was optimized systematically by single-factor experiments and a Box-Behnken experimental design combined with response surface methodology. The maximum extraction yields of prunetin, tectorigenin, genistein and biochanin A reached 1.204, 1.057, 0.911 and 2.448mg/g dry weight, respectively. Moreover, the direct enrichment and separation of four isoflavonoids in DES extraction solution was successfully achieved by macroporous resin AB-8 with recovery yields of more than 80%. The present study provides a convenient and efficient method for the green extraction and preparative separation of active compounds from plants. Copyright © 2016 Elsevier B.V. All rights reserved.

Affinity monolith-integrated poly(methyl methacrylate) microchips for on-line protein extraction and capillary electrophoresis.

PubMed

Sun, Xiuhua; Yang, Weichun; Pan, Tao; Woolley, Adam T

2008-07-01

Immunoaffinity monolith pretreatment columns have been coupled with capillary electrophoresis separation in poly(methyl methacrylate) (PMMA) microchips. Microdevices were designed with eight reservoirs to enable the electrically controlled transport of selected analytes and solutions to carry out integrated immunoaffinity extraction and electrophoretic separation. The PMMA microdevices were fabricated reproducibly and with high fidelity by solvent imprinting and thermal bonding methods. Monoliths with epoxy groups for antibody immobilization were prepared by direct in situ photopolymerization of glycidyl methacrylate and ethylene glycol dimethacrylate in a porogenic solvent consisting of 70% 1-dodecanol and 30% cyclohexanol. Antifluorescein isothiocyanate was utilized as a model affinity group in the monoliths, and the immobilization process was optimized. A mean elution efficiency of 92% was achieved for the monolith-based extraction of fluorescein isothiocyanate (FITC)-tagged human serum albumin. FITC-tagged proteins were purified from a contaminant protein and then separated electrophoretically using these devices. The developed immunoaffinity column/capillary electrophoresis microdevices show great promise for combining sample pretreatment and separation in biomolecular analysis.

Affinity Monolith-Integrated Poly(methyl Methacrylate) Microchips for On-Line Protein Extraction and Capillary Electrophoresis

PubMed Central

Sun, Xiuhua; Yang, Weichun; Pan, Tao; Woolley, Adam T.

2008-01-01

Immunoaffinity monolith pretreatment columns have been coupled with capillary electrophoresis separation in poly(methyl methacrylate) (PMMA) microchips. Microdevices were designed with 8 reservoirs to enable the electrically controlled transport of selected analytes and solutions to carry out integrated immunoaffinity extraction and electrophoretic separation. The PMMA microdevices were fabricated reproducibly and with high fidelity by solvent imprinting and thermal bonding methods. Monoliths with epoxy groups for antibody immobilization were prepared by direct in-situ photopolymerization of glycidyl methacrylate and ethylene dimethacrylate in a porogenic solvent consisting of 70% dodecanol and 30% hexanol. Anti-fluorescein isothiocyanate (FITC) was utilized as a model affinity group in the monoliths, and the immobilization process was optimized. A mean elution efficiency of 92% was achieved for the monolith-based extraction of FITC-tagged human serum albumin. FITC-tagged proteins were purified from a contaminant protein and then separated electrophoretically using these devices. The developed immunoaffinity column/capillary electrophoresis microdevices show great promise for combining sample pretreatment and separation in biomolecular analysis. PMID:18479142

Use of a polar ionic liquid as second column for the comprehensive two-dimensional GC separation of PCBs.

PubMed

Zapadlo, Michal; Krupcík, Ján; Májek, Pavel; Armstrong, Daniel W; Sandra, Pat

2010-09-10

The orthogonality of three columns coupled in two series was studied for the congener specific comprehensive two-dimensional GC separation of polychlorinated biphenyls (PCBs). A non-polar capillary column coated with poly(5%-phenyl-95%-methyl)siloxane was used as the first ((1)D) column in both series. A polar capillary column coated with 70% cyanopropyl-polysilphenylene-siloxane or a capillary column coated with the ionic liquid 1,12-di(tripropylphosphonium)dodecane bis(trifluoromethane-sulfonyl)imide were used as the second ((2)D) columns. Nine multi-congener standard PCB solutions containing subsets of all native 209 PCBs, a mixture of 209 PCBs as well as Aroclor 1242 and 1260 formulations were used to study the orthogonality of both column series. Retention times of the corresponding PCB congeners on (1)D and (2)D columns were used to construct retention time dependences (apex plots) for assessing orthogonality of both columns coupled in series. For a visual assessment of the peak density of PCBs congeners on a retention plane, 2D images were compared. The degree of orthogonality of both column series was, along the visual assessment of distribution of PCBs on the retention plane, evaluated also by Pearson's correlation coefficient, which was found by correlation of retention times t(R,i,2D) and t(R,i,1D) of corresponding PCB congeners on both column series. It was demonstrated that the apolar+ionic liquid column series is almost orthogonal both for the 2D separation of PCBs present in Aroclor 1242 and 1260 formulations as well as for the separation of all of 209 PCBs. All toxic, dioxin-like PCBs, with the exception of PCB 118 that overlaps with PCB 106, were resolved by the apolar/ionic liquid series while on the apolar/polar column series three toxic PCBs overlapped (105+127, 81+148 and 118+106). Copyright 2010 Elsevier B.V. All rights reserved.

Development of Advanced Nuclide Separation and Recovery Methods using Ion-Exchanhge Techniques in Nuclear Backend

NASA Astrophysics Data System (ADS)

Miura, Hitoshi

The development of compact separation and recovery methods using selective ion-exchange techniques is very important for the reprocessing and high-level liquid wastes (HLLWs) treatment in the nuclear backend field. The selective nuclide separation techniques are effective for the volume reduction of wastes and the utilization of valuable nuclides, and expected for the construction of advanced nuclear fuel cycle system and the rationalization of waste treatment. In order to accomplish the selective nuclide separation, the design and synthesis of novel adsorbents are essential for the development of compact and precise separation processes. The present paper deals with the preparation of highly functional and selective hybrid microcapsules enclosing nano-adsorbents in the alginate gel polymer matrices by sol-gel methods, their characterization and the clarification of selective adsorption properties by batch and column methods. The selective separation of Cs, Pd and Re in real HLLW was further accomplished by using novel microcapsules, and an advanced nuclide separation system was proposed by the combination of selective processes using microcapsules.

[Simultaneous determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography].

PubMed

Liu, Min; Li, Xiaolin; Bie, Wei; Wang, Minglin; Feng, Qian

2011-02-01

A new method was established for the determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography (SPE-HPLC). The samples were extracted by methanol-water (1:1, v/v) and purified by a solid phase extraction column. Then, the chromatographic separation was achieved on a Luna C18 column by linear gradient elution. The mobile phase was 10 mmol/L ammonium acetate-acetonitrile (containing 1% acetic acid). The results showed that the 15 industrial synthetic dyes can be separated efficiently. The recoveries of the 15 industrial synthetic dyes spiked in condiment were between 84.6% and 114.2% with the relative standard deviations of 0.9% - 10.3%. The limits of detection of this method was 0.05 - 0.18 mg/kg for the 15 industrial synthetic dyes. The method is simple, sensitive, accurate, repeatable and can be used for simultaneous determination of the 15 illegally added industrial synthetic dyes.

Separation methods applicable to urinary creatine and creatinine.

PubMed

Smith-Palmer, Truis

2002-12-05

Urinary creatinine has been analyzed for many years as an indicator of glomerular filtration rate. More recently, interest in studying the uptake of creatine as a result of creatine supplementation, a practice increasingly common among bodybuilders and athletes, has lead to a need to measure urinary creatine concentrations. Creatine levels are of the same order of magnitude as creatinine levels when subjects have recently ingested creatine, while somewhat elevated urinary creatine concentrations in non-supplementing subjects can be an indication of a degenerative disease of the muscle. Urinary creatine and creatinine can be analyzed by HPLC using a variety of columns. Detection methods include absorption, fluorescence after post-column derivatization, and mass spectrometry, and some methods have been automated. Capillary zone electrophoresis and micellar electrokinetic capillary chromatography have also been used to analyze urinary creatine and creatinine. Creatine and creatinine have also been analyzed in serum and tissue using HPLC and CE, and many of these separations could also be applicable to urinary analysis.

Development of a nucleotide sugar purification method using a mixed mode column & mass spectrometry detection.

PubMed

Eastwood, Heather; Xia, Fang; Lo, Mei-Chu; Zhou, Jing; Jordan, John B; McCarter, John; Barnhart, Wesley W; Gahm, Kyung-Hyun

2015-11-10

Analysis of nucleotide sugars, nucleoside di- and triphosphates and sugar-phosphates is an essential step in the process of understanding enzymatic pathways. A facile and rapid separation method was developed to analyze these compounds present in an enzymatic reaction mixture utilized to produce nucleotide sugars. The Primesep SB column explored in this study utilizes hydrophobic interactions as well as electrostatic interactions with the phosphoric portion of the nucleotide sugars. Ammonium formate buffer was selected due to its compatibility with mass spectrometry. Negative ion mode mass spectrometry was adopted for detection of the sugar phosphate (fucose-1-phophate), as the compound is not amenable to UV detection. Various mobile phase conditions such as pH, buffer concentration and organic modifier were explored. The semi-preparative separation method was developed to prepare 30mg of the nucleotide sugar. (19)F NMR was utilized to determine purity of the purified fluorinated nucleotide sugar. The collected nucleotide sugar was found to be 99% pure. Published by Elsevier B.V.

Method development for speciation analysis of nanoparticle and ionic forms of gold in biological samples by high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Malejko, Julita; Świerżewska, Natalia; Bajguz, Andrzej; Godlewska-Żyłkiewicz, Beata

2018-04-01

A new method based on coupling high performance liquid chromatography (HPLC) to inductively coupled plasma mass spectrometry (ICP MS) has been developed for the speciation analysis of gold nanoparticles (AuNPs) and dissolved gold species (Au(III)) in biological samples. The column type, the composition and the flow rate of the mobile phase were carefully investigated in order to optimize the separation conditions. The usefulness of two polymeric reversed phase columns (PLRP-S with 100 nm and 400 nm pore size) to separate gold species were investigated for the first time. Under the optimal conditions (PLRP-S400 column, 10 mmol L-1 SDS and 5% methanol as the mobile phase, 0.5 mL min-1 flow rate), detection limits of 2.2 ng L-1 for Au(III), 2.8 ng L-1 for 10 nm AuNPs and 3.7 ng L-1 for 40 nm AuNPs were achieved. The accuracy of the method was proved by analysis of reference material RM 8011 (NIST) of gold nanoparticles of nominal diameter of 10 nm. The HPLC-ICP MS method has been successfully applied to the detection and size characterization of gold species in lysates of green algae Acutodesmus obliquus, typical representative of phytoplankton flora, incubated with 10 nm AuNPs or Au(III).

Analysis of free amino acids in Amur sturgeon by ultra-performance liquid chromatography using pre-column derivatization with 6-aminoquinolyl-carbamyl.

PubMed

Sun, Yanchun; Xu, Xianzhu; Mou, Zhenbo; Wang, Jing; Tan, Zhijun; Wu, Song

2012-12-01

A rapid, sensitive, and reliable ultra-performance liquid chromatography (UPLC) coupled with photodiode array detection method was developed for the amino acid analysis of Amur sturgeon (Acipenser schrenckii Brandt). The method uses minimal sample volume and automated online precolumn derivitization of amino acids with fluorescent 6-aminoquinolyl-carbamyl reagent. The chromatographic separation was achieved by UPLC, which used a column with 1.7 μm particle packing that enabled higher speed of analysis, peak capacity, greater resolution, and increased sensitivity. Amino acid derivatives obtained under optimal conditions were separated on a Waters UPLC BEH C(18) column with Acetonitrile-acetate buffer as mobile phase. Matrix effects were investigated and good linearities with correlation coefficients better than 0.9949 were obtained over a wide range of 5-1000 μmol/L for all amino acids. The simple sample preparation and minimal sample volume make the method useful for the quantitation of 17 amino acids in Amur sturgeon samples. It is concluded that a rapid and robust platform based on UPLC was established, and a total of 17 amino acids of Amur sturgeon were tentatively detected. This method showed good accuracy and repeatability that can be used for the quantification of amino acids in real samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous liquid chromatography/mass spectrometry determination of both polar and "multiresidue" pesticides in food using parallel hydrophilic interaction/reversed-phase liquid chromatography and a hybrid sample preparation approach.

PubMed

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

2017-09-29

Pesticide testing of foodstuffs is usually accomplished with generic wide-scope multi-residue methods based on liquid chromatography tandem mass spectrometry (LC-MS/MS). However, this approach does not cover some special pesticides, the so called "single-residue method" compounds, that are hardly compatible with standard reversed-phase (RP) separations due to their specific properties. In this article, we propose a comprehensive strategy for the integration of single residue method compounds and standard multiresidue pesticides within a single run. It is based on the use of a parallel LC column assembly with two different LC gradients performing orthogonal hydrophilic interaction chromatography (HILIC) and reversed-phase (RPLC) chromatography within one analytical run. Two sample aliquots were simultaneously injected on each column, using different gradients, being the eluents merged post-column prior to mass spectrometry detection. The approach was tested with 41 multiclass pesticides covering a wide range of physicochemical properties across several orders of log K ow (from -4 to +5.5). With this assembly, distinct separation from the void was attained for all the pesticides studied, keeping similar performance in terms of sensitivity, peak area reproducibility (<6 RSD% in most cases) and retention time stability of standard single column approaches (better than±0.1min). The application of the proposed approach using parallel HILIC/RPLC and RPLC/aqueous normal phase (Obelisc) were assessed in leek using LC-MS/MS. For this purpose, a hybrid QuEChERS (Quick, easy, cheap, effective, rugged and safe)/QuPPe (quick method for polar pesticides) method was evaluated based on solvent extraction with MeOH and acetonitrile followed by dispersive solid-phase extraction, delivering appropriate recoveries for most of the pesticides included in the study within the log K ow in the range from -4 to +5.5. The proposed strategy may be extended to other fields such as sport drug testing or environmental analysis, where the same type of variety of analytes featuring poor retention within a single chromatographic separation occurs. Copyright © 2017 Elsevier B.V. All rights reserved.

Method for the concentration and separation of actinides from biological and environmental samples

DOEpatents

Horwitz, E.P.; Dietz, M.L.

1989-05-30

A method and apparatus for the quantitative recover of actinide values from biological and environmental sample by passing appropriately prepared samples in a mineral acid solution through a separation column of a dialkyl(phenyl)-N,N-dialylcarbamoylmethylphosphine oxide dissolved in tri-n-butyl phosphate on an inert substrate which selectively extracts the actinide values. The actinide values can be eluted either as a group or individually and their presence quantitatively detected by alpha counting. 3 figs.

Open-tubular capillary electrochromatographic determination of ten sulfonamides in tap water and milk by a metal-organic framework-coated capillary column.

PubMed

Wang, Xuan; Ye, Nengsheng; Hu, Xiaoyu; Liu, Qingye; Li, Jian; Peng, Lin; Ma, Xiaotong

2018-05-25

In this study, a metal-organic framework (MOF), [Mn(cam)(bpy)], was synthesized and characterized by thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectrometry. An open-tubular capillary column was fabricated from [Mn(cam)(bpy)] via the amide coupling method. Ten types of sulfonamides were separated through the fabricated capillary column, which showed a good limits of detection (< 0.07 μg·mL -1 ) and a linear ranges (1-100 μg·mL -1 or 5-100 μg·mL -1 ) with a high correlation coefficients (R 2 > 0.9987). The intra-day, inter-day and column-to-column relative standard deviations (RSDs) in the migration times ranged from 0.44% to 4.87%, and the peak area RSDs ranged from 0.80% to 7.28%. The developed capillary electrochromatography method can be successfully utilized for the determination of sulfonamides in tap water and milk samples. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Polymeric monolith column composited with multiwalled carbon nanotubes-β-cyclodextrin for the selective extraction of psoralen and isopsoralen.

PubMed

Ling, Xu; Zou, Li; Chen, Zilin

2017-09-01

A polymeric column that contains multiwalled carbon nanotubes-β-cyclodextrin composite was developed. The composite was wrapped into the poly(butyl methacrylate-ethylene dimethacrylate) monolith column (0.76 mm id and 10 cm in length). The column was then applied for the online solid-phase microextraction of psoralen and isopsoralen from Fructus Psoraleae. Following microextraction, the coumarins were quantified by high-performance liquid chromatography with C 18 separation column and UV detection. The effects of sample flow rate, sample volume, and pH value were optimized. The method showed low limits of detection (20 pg/mL, S/N = 3) for both psoralen and isopsoralen. Finally the method was successfully applied to the determination of psoralen and isopsoralen in spiked herb extracts and rat plasma where it gave recoveries that ranged between 93.2 and 102.1%. The empty hydrophobic cavities of β-cyclodextrin and the hydrophobicity of multiwalled carbon nanotubes provided specific extraction capability for psoralen and isopsoralen. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ENANTIOMER SEPARATION OF POLYCHLORINATED BIPHENYL ATROPISOMERS AND POLYCHLORINATED BIPHENYL RETENTION BEHAVIOR ON MODIFIED CYCLODEXTRIN CAPILLARY GAS CHROMATOGRAPHY COLUMNS

EPA Science Inventory

Seven commercially-available chiral capillary gas chromatography columns containing modified cyclodextrins were evaluated for their ability to separate enantiomers of the 19 stable chiral polychlorinated biphenyl (PCB) atropisomers, and for their ability to separate these enantio...

SEPARATION OF OCTYLPHENOL POLYETHER ALCOHOLS SURFACTANTS BY CAPILLARY COLUMN AND HPLC

EPA Science Inventory

Separation of nonionic octylphenol polyether alcohols (OPA) by supercritical fluid chromatography (SFC) and HPLC is described. sing a density programming and a 50-pm i.d. capillary column, a total of 18 group oligomers was separated. he effects of the operating parameters, such a...

[Separation and purification of the components in Trachelospermum jasminoides by two dimensional hydrophilic interaction liquid chromatography- reversed-phase liquid chromatography].

PubMed

Jia, Youmei; Cai, Jianfeng; Xin, Huaxia; Feng, Jiatao; Fu, Yanhui; Fu, Qing; Jin, Yu

2017-06-08

A preparative two dimensional hydrophilic interaction liquid chromatography/reversed-phase liquid chromatography (Pre-2D-HILIC/RPLC) method was established to separate and purify the components in Trachelospermum jasminoides . The pigments and strongly polar components were removed from the crude extract after the active carbon decolorization and solid phase extraction processes. A Click XIon column (250 mm×20 mm, 10 μm) was selected as stationary phase and water-acetonitrile as mobile phases in the first dimensional HILIC. Finally, 15 fractions were collected under UV-triggered mode. In the second dimensional RPLC, a C18 column (250 mm×20 mm, 5 μm) was selected and water-acetonitrile was used as mobile phases. As a result, 14 compounds with high purity were obtained, which were further identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR). Finally, 11 lignan compounds and three flavonoid compounds were obtained. The method has a good orthogonality, and can improve the resolution and the peak capacity. It is significant for the separation of complex components from Trachelospermum jasminoides .

Perfusion chromatography separation of the tomato fruit-specific pectin methylesterase from a semipurified commercial enzyme preparation.

PubMed

Savary, B J

2001-08-01

A rapid and simple method was developed, using perfusion chromatography media, to separate the fruit-specific pectin methylesterase (PME) isoform from the depolymerizing enzyme polygalacturonase (PG) and other contaminating pectinases present in a commercial tomato enzyme preparation. Pectinase activities were adsorbed onto a Poros HS (a strong cation exchanger) column in 20 M HEPES buffer at pH 7.5. The fruit-specific PME was eluted from the column with 80 mM NaCl, followed by a step to 300 mM NaCl to elute PG activity. Rechromatography of the PME activity peak with a linear gradient further resolved two PME isoenzymes and removed residual traces of PG activity. The PG activity peak was further treated with lectin affinity chromatography to provide purified PG enzyme, which was separated from a salt-dependent PME (tentatively identified as a "ubiquitous-type" isoform), and a pectin acetylesterase. The later enzyme has not been reported previously in tomato. This method provides monocomponent enzymes that will be useful for studying enzyme mechanisms and for modifying pectin structure and functional properties.

[Determination of penicillin intermediate and three penicillins in milk by high performance capillary electrophoresis].

PubMed

Tian, Chunqiu; Tan, Huarong; Gao, Liping; Shen, Huqin; Qi, Kezong

2011-11-01

A high performance capillary electrophoresis (HPCE) method was developed for the simultaneous determination of penicillin intermediate and penicillins in milk, including 6-amino-penicillanic acid (6-APA), penicillin G (PEN), ampicillin (AMP) and amoxicillin (AMO). The main parameters including the ion concentration and pH value of running buffer, separation voltage and column temperature were optimized systematically by orthogonal test. The four penicillins (PENs) were baseline separated within 4.5 min with the running buffer of 40 mmol/L potassium dihydrogen phosphate-20 mmol/L borax solution (pH 7.8), separation voltage of 28 kV and column temperature of 30 degrees C. The calibration curves showed good linearity in the range of 1.56 - 100 mg/L, and the correlation coefficients (r2) were between 0.9979 and 0.9998. The average recoveries at three spiked levels were in the range of 84.91% - 96.72% with acceptable relative standard deviations (RSDs) of 1.11% - 9.11%. The method is simple, fast, accurate and suitable for the determination of penicillins in real samples.

Pressurized capillary electrochromatographic analysis of water-soluble vitamins by combining with on-line concentration technique.

PubMed

Jia, Li; Liu, Yaling; Du, Yanyan; Xing, Da

2007-06-22

A pressurized capillary electrochromatography (pCEC) system was developed for the separation of water-soluble vitamins, in which UV absorbance was used as the detection method and a monolithic silica-ODS column as the separation column. The parameters (type and content of organic solvent in the mobile phase, type and concentration of electrolyte, pH of the electrolyte buffer, applied voltage and flow rate) affecting the separation resolution were evaluated. The combination of two on-line concentration techniques, namely, solvent gradient zone sharpening effect and field-enhanced sample stacking, was utilized to improve detection sensitivity, which proved to be beneficial to enhance the detection sensitivity by enabling the injection of large volumes of samples. Coupling electrokinetic injection with the on-line concentration techniques was much more beneficial for the concentration of positively charged vitamins. Comparing with the conventional injection mode, the enhancement in the detection sensitivities of water-soluble vitamins using the on-line concentration technique is in the range of 3 to 35-fold. The developed pCEC method was applied to evaluate water-soluble vitamins in corns.

Characterization of non-endcapped polymeric ODS column for the separation of triacylglycerol positional isomers.

PubMed

Gotoh, Naohiro; Matsumoto, Yumiko; Yuji, Hiromi; Nagai, Toshiharu; Mizobe, Hoyo; Ichioka, Kenji; Kuroda, Ikuma; Noguchi, Noriko; Wada, Shun

2010-01-01

The characteristics of a non-endcapped polymeric ODS column for the resolution of triacylglycerol positional isomers (TAG-PI) were examined using a recycle HPLC-atmospheric pressure chemical ionization/mass spectrometry system. A pair of TAG-PI containing saturated fatty acids at least 12 carbons was separated. Except for TAG-PI containing elaidic acid, pairs of TAG-PI containing three unsaturated fatty acids were not separated, even by recycle runs. These results indicate that the resolution of TAG-PI on a non-endcapped polymeric ODS stationary phase is realized by the recognition of the linear structure of the fatty acid and the binding position of the saturated fatty acid in TAG-PI. Chain length was also an important factor for resolution. This method may be a useful and simple for measuring the abundance ratio of TAG-PI containing saturated fatty acids in natural oils.

Method for ultra-trace cesium isotope ratio measurements from environmental samples using thermal ionization mass spectrometry

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

Snow, Mathew S.; Snyder, Darin C.; Mann, Nick R.

2015-05-01

135Cs/ 137Cs isotope ratios can provide the age, origin and history of environmental Cs contamination. Relatively high precision 135Cs/ 137Cs isotope ratio measurements from samples containing femtogram quantities of 137Cs are needed to accurately track contamination resuspension and redistribution following environmental 137Cs releases; however, mass spectrometric analyses of environmental samples are limited by the large quantities of ionization inhibitors and isobaric interferences which are present at relatively high concentrations in the environment. We report a new approach for Cs purification from environmental samples. An initial ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) column provides a robust method for extracting Cs under a wide varietymore » of sample matrices and mass loads. Cation exchange separations using a second AMP-PAN column result in more than two orders of magnitude greater Cs/Rb separation factors than commercially available strong cation exchangers. Coupling an AMP-PAN cation exchanging step to a microcation column (AG50W resin) enables consistent 2-4% (2σ) measurement errors for samples containing 3-6,000 fg 137Cs, representing the highest precision 135Cs/ 137Cs ratio measurements currently reported for soil samples at the femtogram level.« less

Study of different HILIC, mixed-mode, and other aqueous normal-phase approaches for the liquid chromatography/mass spectrometry-based determination of challenging polar pesticides.

PubMed

Vass, Andrea; Robles-Molina, José; Pérez-Ortega, Patricia; Gilbert-López, Bienvenida; Dernovics, Mihaly; Molina-Díaz, Antonio; García-Reyes, Juan F

2016-07-01

The aim of the study was to evaluate the performance of different chromatographic approaches for the liquid chromatography/mass spectrometry (LC-MS(/MS)) determination of 24 highly polar pesticides. The studied compounds, which are in most cases unsuitable for conventional LC-MS(/MS) multiresidue methods were tested with nine different chromatographic conditions, including two different hydrophilic interaction liquid chromatography (HILIC) columns, two zwitterionic-type mixed-mode columns, three normal-phase columns operated in HILIC-mode (bare silica and two silica-based chemically bonded columns (cyano and amino)), and two standard reversed-phase C18 columns. Different sets of chromatographic parameters in positive (for 17 analytes) and negative ionization modes (for nine analytes) were examined. In order to compare the different approaches, a semi-quantitative classification was proposed, calculated as the percentage of an empirical performance value, which consisted of three main features: (i) capacity factor (k) to characterize analyte separation from the void, (ii) relative response factor, and (iii) peak shape based on analytes' peak width. While no single method was able to provide appropriate detection of all the 24 studied species in a single run, the best suited approach for the compounds ionized in positive mode was based on a UHPLC HILIC column with 1.8 μm particle size, providing appropriate results for 22 out of the 24 species tested. In contrast, the detection of glyphosate and aminomethylphosphonic acid could only be achieved with a zwitterionic-type mixed-mode column, which proved to be suitable only for the pesticides detected in negative ion mode. Finally, the selected approach (UHPLC HILIC) was found to be useful for the determination of multiple pesticides in oranges using HILIC-ESI-MS/MS, with limits of quantitation in the low microgram per kilogram in most cases. Graphical Abstract HILIC improves separation of multiclass polar pesticides.

Improved quality control of [18F]fluoromethylcholine.

PubMed

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

2011-11-01

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

Gradient HPLC of antibiotics in urine, ground water, chicken muscle, hospital wastewater, and pharmaceutical samples using C-18 and RP-amide columns.

PubMed

Kumar, Ashwini; Kumar Malik, Ashok; Kumar Tewary, Dhananjay; Singh, Baldev

2008-02-01

A simple and highly sensitive high pressure liquid chromatographic (HPLC-UV) method has been developed for the determination of ofloxacin, lomefloxacin, cinoxacin, and nalidixic acid, in mobile phase citrate buffer (0.001 M) of pH 4.5 prepared in water (X), methanol (Y), and ACN (Z) using gradient at a flow rate of 1.0 mL/min by direct UV absorbance detection at lambda = 280 nm. Separation of analytes was studied on the C-18 and RP-amide columns and best results were observed on the RP-amide column with LODs (3.3 x S/m) 0.89, 0.55, 0.67, and 1.41 ng/mL for ofloxacin, lomefloxacin, cinoxacin, and nalidixic acid, respectively, and better RSD than the C-18 column. The recovery of Fluoroquinolones (FQs) in urine, ground water, hospital wastewater, and chicken muscle using this method is more than 90%. The method was successfully applied to the analysis of ofloxacin, lomefloxacin, cinoxacin, and nalidixic acid in urine, ground water, pharmaceutical dosage forms, hospital wastewater, and chicken muscle.

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

PubMed

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

2009-02-01

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

Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography

PubMed Central

Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim

2016-01-01

A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na+), potassium (K+), ammonium (NH4+), chloride (Cl−) and nitrate (NO3−) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples. PMID:26786906

Graphene oxide sheets immobilized polystyrene for column preconcentration and sensitive determination of lead by flame atomic absorption spectrometry.

PubMed

Islam, Aminul; Ahmad, Hilal; Zaidi, Noushi; Kumar, Suneel

2014-08-13

A novel solid-phase extractant was synthesized by coupling graphene oxide (GO) on chloromethylated polystyrene through an ethylenediamine spacer unit to develop a column method for the preconcentration/separation of lead prior to its determination by flame atomic absorption spectrometry. It was characterized by Fourier transform infrared spectroscopy, far-infrared spectroscopy, thermogravimetric analysis/differential thermal analysis, scanning electron microscopy, energy-dispersive spectrometry, and transmission electron microscopy. The abundant oxygen-containing surface functional groups form a strong complex with lead, resulting in higher sorption capacity (227.92 mg g(-1)) than other nanosorbents used for sorption studies of the column method. Using the column procedure here is an alternative to the direct use of GO, which restricts irreversible aggregation of GO and its escape into the ecosystem, making it an environmentally sustainable method. The column method was optimized by varying experimental variables such as pH, flow rate for sorption/desorption, and elution condition and was observed to exhibit a high preconcentration factor (400) with a low preconcentration limit (2.5 ppb) and a high degree of tolerance for matrix ions. The accuracy of the proposed method was verified by determining the Pb content in the standard reference materials and by recovery experiments. The method showed good precision with a relative standard deviation <5%. The proposed method was successfully applied for the determination of lead in tap water, electroplating wastewater, river water, and food samples after preconcentration.

Separation of Albumin, Ceruloplasmin, and Transferrin from Human Plasma.

ERIC Educational Resources Information Center

Barnes, Grady; Frieden, Earl

1982-01-01

Procedures are provided for separating the principal metalloproteins (albumin, ceruloplasmin, and transferrin) from plasma using column chromatographic techniques. The experiment can be completed in two separate three-hour laboratory periods during which column chromatography is illustrated and the effect of pH on charge and affinity of a protein…

Radial Chromatography for the Separation of Nitroaniline Isomers

ERIC Educational Resources Information Center

Miller, Robert B.; Case, William S.

2011-01-01

Separation techniques are usually presented in the undergraduate organic laboratory to teach students how to purify and isolate compounds. Often the concept of liquid chromatography is introduced by having students create "silica gel columns" to separate components of a reaction mixture. Although useful, column chromatography can be a laborious…

EFFECTS OF TEMPERATURE AND SOLVENT COMPOSITION ON THE CHIRALCEL OJ SEPARATION OF CHIRAL ORGANOPHOSPHORUS PESTICIDES

EPA Science Inventory

The separation of the enantiomers of twelve organophosphorus pesticides (OPs) was investigated on the CHIRALCEL?OJ column to determine whether the mobile phase composition, flow rate and column temperature could be optimized to yield at least partial separation of the enantiomers...

SEPARATION OF OCTYLPHENOL POLYETHER ALCOHOLS SURFACTANTS BY CAPILLARY COLUMN SFC AND HPLC

EPA Science Inventory

Separation of nonionic octylphenol polyether alcohols (OPA) by supercritical fluid chromatography (SFC) and HPLC is described. Using a density programming and a 50-μm i.d. capillary column, a total of 18 group oligomers was separated. The effects of the operating parameters, such...

Oak ridge national laboratory automated clean chemistry for bulk analysis of environmental swipe samples

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

Bostick, Debra A.; Hexel, Cole R.; Ticknor, Brian W.

2016-11-01

To shorten the lengthy and costly manual chemical purification procedures, sample preparation methods for mass spectrometry are being automated using commercial-off-the-shelf (COTS) equipment. This addresses a serious need in the nuclear safeguards community to debottleneck the separation of U and Pu in environmental samples—currently performed by overburdened chemists—with a method that allows unattended, overnight operation. In collaboration with Elemental Scientific Inc., the prepFAST-MC2 was designed based on current COTS equipment that was modified for U/Pu separations utilizing Eichrom™ TEVA and UTEVA resins. Initial verification of individual columns yielded small elution volumes with consistent elution profiles and good recovery. Combined columnmore » calibration demonstrated ample separation without crosscontamination of the eluent. Automated packing and unpacking of the built-in columns initially showed >15% deviation in resin loading by weight, which can lead to inconsistent separations. Optimization of the packing and unpacking methods led to a reduction in the variability of the packed resin to less than 5% daily. The reproducibility of the automated system was tested with samples containing 30 ng U and 15 pg Pu, which were separated in a series with alternating reagent blanks. These experiments showed very good washout of both the resin and the sample from the columns as evidenced by low blank values. Analysis of the major and minor isotope ratios for U and Pu provided values well within data quality limits for the International Atomic Energy Agency. Additionally, system process blanks spiked with 233U and 244Pu tracers were separated using the automated system after it was moved outside of a clean room and yielded levels equivalent to clean room blanks, confirming that the system can produce high quality results without the need for expensive clean room infrastructure. Comparison of the amount of personnel time necessary for successful manual vs. automated chemical separations showed a significant decrease in hands-on time from 9.8 hours to 35 minutes for seven samples, respectively. This documented time savings and reduced labor translates to a significant cost savings per sample. Overall, the system will enable faster sample reporting times at reduced costs by limiting personnel hours dedicated to the chemical separation.« less

A method of isolating organic compounds present in water

NASA Technical Reports Server (NTRS)

Calder, G. V.; Fritz, J.; Junk, G. A.

1972-01-01

Water sample is passed through a column containing macroreticular resin, which absorbs only nonionic organic compounds. These compounds are selectively separated using aqueous eluents of varying pH, or completely exuded with small amount of an organic eluent.

Rapid chromatographic separation of dissoluble Ag(I) and silver-containing nanoparticles of 1-100 nanometer in antibacterial products and environmental waters.

PubMed

Zhou, Xiao-Xia; Liu, Rui; Liu, Jing-Fu

2014-12-16

Sensitive and rapid methods for speciation analysis of nanoparticulate Ag (NAg) and Ag(I) in complex matrices are urgently needed for understanding the environmental effects and biological toxicity of silver nanoparticles (AgNPs). Herein we report the development of a universal liquid chromatography (LC) method for rapid and high resolution separation of dissoluble Ag(I) from nanoparticles covering the entire range of 1-100 nm in 5 min. By using a 500 Å poresize amino column, and an aqueous mobile phase containing 0.1% (v/v) FL-70 (a surfactant) and 2 mM Na2S2O3 at a flow rate of 0.7 mL/min, all the nanoparticles of various species such as Ag and Ag2S were eluted in one fraction, while dissoluble Ag(I) was eluted as a baseline separated peak. The dissoluble Ag(I) was quantified by the online coupled ICP-MS with a detection limit of 0.019 μg/L. The NAg was quantified by subtracting the dissoluble Ag(I) from the total Ag content, which was determined by ICP-MS after digestion of the sample without LC separation. While the addition of FL-70 and Na2S2O3 into the mobile phase is essential to elute NAg and Ag(I) from the column, the use of 500 Å poresize column is the key to baseline separation of Ag(I) from ∼ 1 nm AgNPs. The feasibility of the proposed method was demonstrated in speciation analysis of dissoluble Ag(I) and NAg in antibacterial products and environmental waters, with very good chromatographic repeatability (relative standard deviations) in both peak area (<2%) and retention time (<0.6%), excellent spiked recoveries in the range of 84.7-102.7% for Ag(I) and 81.3-106.3% for NAg. Our work offers a novel approach to rapid and baseline separation of dissoluble metal ions from their nanoparticulate counterparts covering the whole range of 1-100 nm.

Liquid chromatography determination of 10-hydroxycamptothecin in human serum by a column-switching system containing a pre-column with restricted access media and its application to a clinical pharmacokinetic study.

PubMed

Ma, Jun; Jia, Zheng-Ping; Zhang, Qiang; Fan, Jun-Jie; Jiang, Ning-Xi; Wang, Rong; Xie, Hua; Wang, Juan

2003-10-25

A simple, rapid, sensitive column-switching HPLC method is described for the analysis of the 10-hydroxycamptothecin (HCPT) in human serum. A pre-column containing restricted access media (RAM) is used for the sample clean-up and trace enrichment and is combined with a C18 column for the final separation. The analytical time is 8 min. The HCPT is monitored with fluorescence detector, excitation and emission wavelengths being 385 and 539 nm, respectively. There is a linear response range of 1-1000 ng/ml with correlation coefficient of 0.998 while the limit of quantification is 0.1 ng/ml. The intra-day and inter-day variations are less than 5%. This analytic procedure has been applied to a pharmacokinetic study of HCPT in clinical patients and the pharmacokinetic parameters of one-compartment model are calculated.

Quantitative and pattern recognition analyses of magnoflorine, spinosin, 6'''-feruloyl spinosin and jujuboside A by HPLC in Zizyphi Semen.

PubMed

Kim, Won Il; Zhao, Bing Tian; Zhang, Hai Yan; Lee, Je Hyun; Son, Jong Keun; Woo, Mi Hee

2014-01-01

Two rapid and simple HPLC methods with UV detector to determine three main compounds (magnoflorine, spinosin and 6'''-feruloyl spinosin) and evaporative light scattering detector (ELSD) to determine jujuboside A were developed for the chemical analyses of Zizyphi Semen. Magnoflorine, spinosin, and 6'''-feruloyl spinosin were separated with an YMC J'sphere ODS-H80 column (250 mm × 4.6 mm, 4 μm) by the gradient elution followed by the isocratic elution using methanol with 0.1 % formic acid and water with 0.1 % formic acid as the mobile phase. The flow rate was 1.0 mL/min. Jujuboside A was separated by HPLC-ELSD with YoungJinBioChrom Aegispak C18-L column (250 mm × 4.6 mm, 5 μm) column in a gradient elution using methanol with 0.1 % formic acid (A) and water with 0.1 % formic acid as the mobile phase. These two methods were fully validated with respect to linearity, precision, accuracy, stability, and robustness. These HPLC methods were applied successfully to quantify four compounds in a Zizyphi Semen extract. The HPLC analytical methods were validated for pattern recognition analysis by repeated analysis of 91 seed samples corresponding to 48 Zizyphus jujuba var. spinosa (J01-J48) and 43 Zizyphus mauritiana (M01-M43). The results indicate that these methods are suitable for a quality evaluation of Zizyphi Semen.

Comparison in partition efficiency of protein separation between four different tubing modifications in spiral high-speed countercurrent chromatography

PubMed Central

Ito, Yoichiro; Clary, Robert

2016-01-01

High-speed countercurrent chromatography with a spiral tube assembly can retain a satisfactory amount of stationary phase of polymer phase systems used for protein separation. In order to improve the partition efficiency a simple tool to modify the tubing shapes was fabricated, and the following four different tubing modifications were made: intermittently pressed at 10 mm width, flat, flat-wave, and flat-twist. Partition efficiencies of the separation column made from these modified tubing were examined in protein separation with an aqueous-aqueous polymer phase system at flow rates of 1–2 ml/min under 800 rpm. The results indicated that the column with all modified tubing improved the partition efficiency at a flow rate of 1 ml/min, but at a higher flow rate of 2 ml/min the columns made of flattened tubing showed lowered partition efficiency apparently due to the loss of the retained stationary phase. Among all the modified columns, the column with intermittently pressed tubing gave the best peak resolution. It may be concluded that the intermittently pressed and flat-twist improve the partition efficiency in a semi-preparative separation while other modified tubing of flat and flat-wave configurations may be used for analytical separations with a low flow rate. PMID:27790621

Comparison in partition efficiency of protein separation between four different tubing modifications in spiral high-speed countercurrent chromatography.

PubMed

Ito, Yoichiro; Clary, Robert

2016-12-01

High-speed countercurrent chromatography with a spiral tube assembly can retain a satisfactory amount of stationary phase of polymer phase systems used for protein separation. In order to improve the partition efficiency a simple tool to modify the tubing shapes was fabricated, and the following four different tubing modifications were made: intermittently pressed at 10 mm width, flat, flat-wave, and flat-twist. Partition efficiencies of the separation column made from these modified tubing were examined in protein separation with an aqueous-aqueous polymer phase system at flow rates of 1-2 ml/min under 800 rpm. The results indicated that the column with all modified tubing improved the partition efficiency at a flow rate of 1 ml/min, but at a higher flow rate of 2 ml/min the columns made of flattened tubing showed lowered partition efficiency apparently due to the loss of the retained stationary phase. Among all the modified columns, the column with intermittently pressed tubing gave the best peak resolution. It may be concluded that the intermittently pressed and flat-twist improve the partition efficiency in a semi-preparative separation while other modified tubing of flat and flat-wave configurations may be used for analytical separations with a low flow rate.

Estimations of temperature deviations in chromatographic columns using isenthalpic plots. I. Theory for isocratic systems.

PubMed

Tarafder, Abhijit; Iraneta, Pamela; Guiochon, Georges; Kaczmarski, Krzysztof; Poe, Donald P

2014-10-31

We propose to use constant enthalpy or isenthalpic diagrams as a tool to estimate the extent of the temperature variations caused by the mobile phase pressure drop along a chromatographic column, e.g. of its cooling in supercritical fluid and its heating in ultra-performance liquid chromatography. Temperature strongly affects chromatographic phenomena. Any of its variations inside the column, whether intended or not, can lead to significant changes in separation performance. Although instruments use column ovens in order to keep constant the column temperature, operating conditions leading to a high pressure drop may cause significant variations of the column temperature, both in the axial and the radial directions, from the set value. Different ways of measuring these temperature variations are available but they are too inconvenient to be employed in many practical situations. In contrast, the thermodynamic plot-based method that we describe here can easily be used with only a ruler and a pencil. They should be helpful in developing methods or in analyzing results in analytical laboratories. Although the most effective application area for this approach should be SFC (supercritical fluid chromatography), it can be applied to any chromatographic conditions in which temperature variations take place along the column due to the pressure drop, e.g. in ultra-high pressure liquid chromatography (UHPLC). The method proposed here is applicable to isocractic conditions only. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of alpha-hydroxy acids in cosmetic products by high-performance liquid chromatography with a narrow-bore column.

PubMed

Nicoletti, I; Corradini, C; Cogliandro, E; Cavazza, A

1999-08-01

This paper reports the results of a study carried out to develop a simple, rapid and sensitive method for the separation, identification and quantitative measurement of alpha-hydroxy acids in commercial cosmetics using high-performance liquid chromatography (HPLC). This method is successfully applied to the simultaneous identification and quantitative determination of glycolic, lactic, malic, tartaric and citric acids employing a reversed phase narrow-bore column under isocratic condition and UV detection. The method is validated by determining the precision of replicate analyses and accuracy by analyzing samples with and without adding know amount of the alpha-hydroxy acids. The procedure is suitable for routine analyses of commercial cosmetics.

Monolithic stationary phases with a longitudinal gradient of porosity.

PubMed

Urban, Jiří; Hájek, Tomáš; Svec, Frantisek

2017-04-01

The duration of the hypercrosslinking reaction has been used to control the extent of small pores formation in polymer-based monolithic stationary phases. Segments of five columns hypercrosslinked for 30-360 min were coupled via zero-volume unions to prepare columns with segmented porosity gradients. The steepness of the porosity gradient affected column efficiency, mass transfer resistance, and separation of both small-molecule alkylbenzenes and high-molar-mass polystyrene standards. In addition, the segmented column with the steepest porosity gradient was prepared as a single column with a continuous porosity gradient. The steepness of porosity gradient in this type column was tuned. Compared to a completely hypercrosslinked column, the column with the shallower gradient produced comparable size-exclusion separation of polystyrene standards but allowed higher column permeability. The completely hypercrosslinked column and the column with porosity gradient were successfully coupled in online two-dimensional liquid chromatography of polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Ostrovskii, G.M.; Platonov, V.M.; Zhvanetskii, I.B.

The problem of designing optimum rectification separation systems (r.s.) in two-section columns with heat recovery is discussed. This is an important problem because the cost of the energy consumed can reached 70% of the total cost of the r.s. It is shown that the problem may be reduced to one of integral linear programming, for which well-developed methods of solution are available. It is assumed that: 1) the pressure is constant in all rectification columns, and 2) the streams may exchange heat only once.

Separation of isotopes by cyclical processes

DOEpatents

Hamrin, Jr., Charles E.; Weaver, Kenny

1976-11-02

Various isotopes of hydrogen are separated by a cyclic sorption process in which a gas stream containing the isotopes is periodically passed through a high pressure column containing a palladium sorbent. A portion of the product from the high pressure column is passed through a second column at lower pressure to act as a purge. Before the sorbent in the high pressure column becomes saturated, the sequence is reversed with the stream flowing through the former low-pressure column now at high pressure, and a portion of the product purging the former high pressure column now at low pressure. The sequence is continued in cyclic manner with the product being enriched in a particular isotope.

COMPUTER-ASSISTED HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY METHOD DEVELOPMENT WITH APPLICATIONS TO THE ISOLATION AND ANALYSIS OF PHYTOPLANKTON PIGMENTS. (R826944)

EPA Science Inventory

We used chromatography modeling software to assist in HPLC method development, with the goal
of enhancing separations through the exclusive use of gradient time and column temperature. We
surveyed nine stationary phases for their utility in pigment purification and natur...

Quantitative structure-retention relationship models for the prediction of the reversed-phase HPLC gradient retention based on the heuristic method and support vector machine.

PubMed

Du, Hongying; Wang, Jie; Yao, Xiaojun; Hu, Zhide

2009-01-01

The heuristic method (HM) and support vector machine (SVM) were used to construct quantitative structure-retention relationship models by a series of compounds to predict the gradient retention times of reversed-phase high-performance liquid chromatography (HPLC) in three different columns. The aims of this investigation were to predict the retention times of multifarious compounds, to find the main properties of the three columns, and to indicate the theory of separation procedures. In our method, we correlated the retention times of many diverse structural analytes in three columns (Symmetry C18, Chromolith, and SG-MIX) with their representative molecular descriptors, calculated from the molecular structures alone. HM was used to select the most important molecular descriptors and build linear regression models. Furthermore, non-linear regression models were built using the SVM method; the performance of the SVM models were better than that of the HM models, and the prediction results were in good agreement with the experimental values. This paper could give some insights into the factors that were likely to govern the gradient retention process of the three investigated HPLC columns, which could theoretically supervise the practical experiment.

Design of a portable gas chromatography with a conducting polymer nanocomposite detector device and a method to analyze a gas mixture.

PubMed

Pirsa, Sajad

2017-04-01

A portable chromatography device and a method were developed to analyze a gas mixture. The device comprises a chromatographic column for separating components of a sample of the gas mixture. It has an air pump coupled to the inlet of a chromatographic column for pumping air and an injector coupled to the inlet of chromatographic column for feeding the sample using the air as a carrier gas. A detector is arranged downstream from and coupled to the outlet of the chromatographic column. The detector is a nanostructure semiconductive microfiber. The device further comprises an evaluation unit arranged and configured to evaluate each detected component to determine the concentration. The designed portable system was used for simultaneous detection of amines. The possibility of applying dispersive liquid-liquid microextraction for the determination of analytes in trace levels is demonstrated. The reproducibility of this method is acceptable, and good standard deviations were obtained. The relative standard deviation value is less than 6% for all analytes. Finally, the method was successfully applied to the extraction and determination of analytes in water samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Precolumn derivatization followed by liquid chromatographic separation and determination of tramiprosate in rat plasma by fluorescence detector: application to pharmacokinetics.

PubMed

Rao, R Nageswara; Maurya, Pawan K; Shinde, Dhananjay D; Khalid, Sara

2011-05-15

Alzheimer disease (AD) is characterized pathologically by extracellular amyloid deposits composed of amyloid β (Aβ) protein. A simple and rapid method using HPLC with fluorescence detector was developed and validated for determination of tramiprosate in rat plasma. Pre-column derivatization of the deproteinized rat plasma was carried out using o-phthaldialdehyde (OPA) as a fluorescent reagent in presence of 3-mercaptopropionic acid. The liquid chromatographic separation was achieved on a Kromasil C18 column using methanol:acetonitrile: 20 mM phosphate buffer pH 7.5 (8.0:17.5:74.5 v/v/v) as a mobile phase in an isocratic elution mode. The eluents were monitored by a fluorescence detector set at 330 and 450 nm of excitation and emission wavelength respectively. Vigabatrin was used as an internal standard. The method was linear within the range 30.0-1000.0 ng/mL. Design of experiments (DOE) was used to evaluate the robustness of the method. The developed method was applied to study the pharmacokinetics of tramiprosate in rats. Copyright © 2011. Published by Elsevier B.V.

Direct-injection HPLC method of measuring micafungin in human plasma using a novel hydrophobic/hydrophilic hybrid ODS column.

PubMed

Uranishi, Hiroaki; Nakamura, Mitsuhiro; Nakamura, Hiroki; Ikeda, Yukari; Otsuka, Mayuko; Kato, Zenichiro; Tsuchiya, Teruo

2011-04-15

A direct-injection HPLC-based method has been developed for determining amounts of micafungin in human plasma using a novel hydrophobic/hydrophilic hybrid ODS column. The method is easy to perform and requires only 10 μL of a filtered plasma sample. The chromatographic separations were carried out with a gradient mode. The fluorescence detection wavelengths of excitation and emission were set at 273 nm and 464 nm, respectively. Retention times for micafungin and IS were 22.4 and 23.7 min, respectively. Micafungin and FR195743 (IS) peaks were completely separated with little tailing, and no interference was observed. The calibration curve of micafungin showed good linearity in the range of 0.5-20.0 μg/mL (r(2)=1.00). The intra-day accuracy ranged from -4.5 to 5.3%. The inter-day accuracy ranged from -9.8 to 1.5%. The precisions were less than 10%. This method is useful for the determination of micafungin in human plasma. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterization of cis- and trans-octadecenoic acid positional isomers in edible fat and oil using gas chromatography-flame ionisation detector equipped with highly polar ionic liquid capillary column.

PubMed

Yoshinaga, Kazuaki; Asanuma, Masaharu; Mizobe, Hoyo; Kojima, Koichi; Nagai, Toshiharu; Beppu, Fumiaki; Gotoh, Naohiro

2014-10-01

In this study, the characterisation of all cis- and trans-octadecenoic acid (C18:1) positional isomers in partially hydrogenated vegetable oil (PHVO) and milk fat, which contain several cis- and trans-C18:1 positional isomers, was achieved by gas chromatography-flame ionisation detector equipped with a highly polar ionic liquid capillary column (SLB-IL111). Prior to analysis, the cis- and trans-C18:1 fractions in PHVO and milk fat were separated using a silver-ion cartridge. The resolution of all cis-C18:1 positional isomers was successfully accomplished at the optimal isothermal column temperature of 120 °C. Similarly, the positional isomers of trans-C18:1, except for trans-6-C18:1 and trans-7-C18:1, were separated at 120 °C. The resolution of trans-6-C18:1 and trans-7-C18:1 isomers was made possible by increasing the column temperature to 160 °C. This analytical method is suitable for determining the cis- and trans-C18:1 positional isomers in edible fats and oils. Copyright © 2014 Elsevier Ltd. All rights reserved.

Repeatability of gradient ultrahigh pressure liquid chromatography-tandem mass spectrometry methods in instrument-controlled thermal environments.

PubMed

Grinias, James P; Wong, Jenny-Marie T; Kennedy, Robert T

2016-08-26

The impact of viscous friction on eluent temperature and column efficiency in liquid chromatography is of renewed interest as the need for pressures exceeding 1000bar to use with columns packed with sub-2μm particles has grown. One way the development of axial and radial temperature gradients that arise due to viscous friction can be affected is by the thermal environment the column is placed in. In this study, a new column oven integrated into an ultrahigh pressure liquid chromatograph that enables both still-air and forced-air operating modes is investigated to find the magnitude of the effect of the axial thermal gradient that forms in 2.1×100mm columns packed with sub-2μm particles in these modes. Temperature increases of nearly 30K were observed when the generated power of the column exceeded 25W/m. The impact of the heating due to viscous friction on the repeatability of peak capacity, elution time, and peak area ratio to an internal standard for a gradient UHPLC-MS/MS method to analyze neurotransmitters was found to be limited. This result indicates that high speed UHPLC-MS/MS gradient methods under conditions of high viscous friction may be possible without the negative effects typically observed with isocratic separations under similar conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Behavior of macroporous vinyl silica and silica monolithic columns in high pressure gas chromatography.

PubMed

Maniquet, Adrien; Bruyer, Nicolas; Raffin, Guy; Baco-Antionali, Franck; Demesmay, Claire; Dugas, Vincent; Randon, Jérôme

2017-06-30

80% vinyltrimethoxysilane-based hybrid silica monoliths (80-VTMS), which have been initially developed for separation in reversed-phase liquid chromatography, have been investigated in high pressure gas chromatography separations (carrier gas pressure up to 60bar) and compared to silica monolithic columns. The behavior of both silica and 80-VTMS monolithic columns was investigated using helium, nitrogen and carbon dioxide as carrier gas. The efficiency of 80-VTMS monolithic columns was shown to vary differently than silica monolithic columns according to the temperature and the carrier gas used. Carrier gas nature was a significant parameter on the retention for both silica and vinyl columns in relation to its adsorption onto the stationary phase in such high pressure conditions. The comparison of retention and selectivity between 80-VTMS monoliths and silica was performed under helium using the logarithm of the retention factor according to the number of carbon atoms combined to Kovats indexes. The very good performances of these columns were demonstrated, allowing the separation of 8 compounds in less than 1min. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of various second-dimension gradient types in comprehensive two-dimensional liquid chromatography.

PubMed

Jandera, Pavel; Hájek, Tomás; Cesla, Petr

2010-06-01

Gradient elution provides significant improvement in peak capacity with respect to isocratic conditions. In the second dimension, gradients are limited to a short-time period available for separation. Various types of second-dimension gradients in comprehensive LC x LC are compared: (i) "full in fraction", (ii) "segment in fraction" and (iii) "continuously shifting" gradients, applied in orthogonal LC x LC separations of phenolic acids and flavones on a polyethylene glycol column in the first dimension and two types of porous shell fused-core C18 columns in the second dimension (Ascentis Express and Kinetex). The porous shell columns provide narrow bandwidths and fast second-dimension separations at moderate operating pressure that allows important savings of the overall separation time in comprehensive LC x LC separations. The effects of the gradient type on the bandwidths, theoretical peak capacity, separation time and column pressure in the second dimension were investigated. The type of gradient program controls the range of lipophilicity of sample compounds that can be separated in the second-dimension reversed-phase time period. This range can be calibrated using alkylbenzene standards, to design the separation conditions for complete sample separation, avoiding harmful wrap around of non-eluted compounds to the subsequent second-dimension fractions.

Adsorption and separation of proteins by collagen fiber adsorbent.

PubMed

Li, Juan; Liao, Xue-pin; Zhang, Qi-xian; Shi, Bi

2013-06-01

The separation of proteins is a key step in biomedical and pharmaceutical industries. In the present investigation, the collagen fiber adsorbent (CFA) was exploited as column packing material to separate proteins. Bovine serum albumin (BSA), bovine hemoglobin (Hb) and lysozyme (LYS) that have different isoelectric points (pIs) were selected as model proteins to investigate the separation ability of CFA to proteins. In batch adsorption, the adsorption behaviors of these proteins on CFA under different pHs and ionic strengths indicated that the electrostatic interaction plays a predominant role in the adsorption of proteins on CFA. CFA exhibited high adsorption capacity to Hb and LYS. In column separation, the proteins were completely separated by adjusting pH and ionic strength of the eluent. The increase of flow rate could reduce the separation time with no influence on the recovery of protein in the experimental range. The protein recovery was higher than 90% even when the CFA column was re-used for 4 times in separation of BSA and LYS, and the retention time of BSA or LYS was almost constant during the repeated applications. In addition, as a practical application, LYS was successfully separated from chicken egg white powder by CFA column. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation of transition metals on a poly-iminodiacetic acid grafted polymeric resin column with post-column reaction detection utilising a paired emitter-detector diode system.

PubMed

Barron, Leon; O'Toole, Martina; Diamond, Dermot; Nesterenko, Pavel N; Paull, Brett

2008-12-05

The selectivity, retention and separation of transition metals on a short (2 mm x 50 mm) column packed with a poly-iminodiacetic acid functionalised polymer 10 microm resin (Dionex ProPac IMAC-10) are presented. This stationary phase, typically used for the separation of proteins, is composed of long chain poly-iminodiacetic acid groups grafted to a hydrophilic layer surrounding a 10 microm polymeric bead. Through the use of a combination of a multi-step pH and picolinic acid gradient, the separation of magnesium, iron, cobalt, cadmium, zinc, lead and copper was possible, followed by post-column reaction with 4-(2-pyridylazo) resorcinol (PAR) and absorbance detection at 510 nm using a novel and inexpensive optical detector, comprised of two light emitting diodes with one acting as a light source and the other as a detector. Column efficiency for selective transition metals was in excess of N=10,000, with the baseline separation of seven metal cations in <3 min possible under optimised conditions. Detection limits of between 5 and 81 microg/L were possible based upon a 50 microL injection volume.

Chiral stationary phase optimized selectivity liquid chromatography: A strategy for the separation of chiral isomers.

PubMed

Hegade, Ravindra Suryakant; De Beer, Maarten; Lynen, Frederic

2017-09-15

Chiral Stationary-Phase Optimized Selectivity Liquid Chromatography (SOSLC) is proposed as a tool to optimally separate mixtures of enantiomers on a set of commercially available coupled chiral columns. This approach allows for the prediction of the separation profiles on any possible combination of the chiral stationary phases based on a limited number of preliminary analyses, followed by automated selection of the optimal column combination. Both the isocratic and gradient SOSLC approach were implemented for prediction of the retention times for a mixture of 4 chiral pairs on all possible combinations of the 5 commercial chiral columns. Predictions in isocratic and gradient mode were performed with a commercially available and with an in-house developed Microsoft visual basic algorithm, respectively. Optimal predictions in the isocratic mode required the coupling of 4 columns whereby relative deviations between the predicted and experimental retention times ranged between 2 and 7%. Gradient predictions led to the coupling of 3 chiral columns allowing baseline separation of all solutes, whereby differences between predictions and experiments ranged between 0 and 12%. The methodology is a novel tool allowing optimizing the separation of mixtures of optical isomers. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of three anticonvulsants using hydrophilic interaction LC-MS.

PubMed

Oertel, Reinhard; Arenz, Norman; Pietsch, Jörg; Kirch, Wilhelm

2009-01-01

A specific and automated method was developed to quantify the anticonvulsants gabapentin, pregabalin and vigabatrin simultaneously in human serum. Samples were prepared with a protein precipitation. The hydrophilic interaction chromatography (HILIC) with a mobile phase gradient was used to divide off ions of the matrix and for separation of the analytes. Four different HILIC-columns and two different column temperatures were tested. The Tosoh-Amid column gave the best results: single small peaks. The anticonvulsants were detected in the multiple reaction monitoring mode (MRM) with ESI-MS-MS. Using a volume of 100 microL biological sample the lowest point of the standard curve, i.e. the lower LOQs were 312 ng/mL. The described HILIC-MS-MS method is suitable for therapeutic drug monitoring and for clinical and pharmcokinetical investigations of the anticonvulsives.

Comparative study of new shell-type, sub-2 micron fully porous and monolith stationary phases, focusing on mass-transfer resistance.

PubMed

Oláh, Erzsébet; Fekete, Szabolcs; Fekete, Jeno; Ganzler, Katalin

2010-06-04

Today sub-2 microm packed columns are very popular to conduct fast chromatographic separations. The mass-transfer resistance depends on the particle size but some practical limits exist not to reach the theoretically expected plate height and mass-transfer resistance. Another approach applies particles with shortened diffusion path to enhance the efficiency of separations. In this study a systematical evaluation of the possibilities of the separations obtained with 5 cm long narrow bore columns packed with new 2.6 microm shell particles (1.9 microm nonporous core surrounded by a 0.35 microm porous shell, Kinetex, Core-Shell), packed with other shell-type particles (Ascentis Express, Fused-Core), totally porous sub-2 microm particles and a 5 cm long narrow bore monolith column is presented. The different commercially available columns were compared by using van Deemter, Knox and kinetic plots. Theoretical Poppe plots were constructed for each column to compare their kinetic performance. Data are presented on polar neutral real-life analytes. Comparison of a low molecular weight compounds (MW=270-430) and a high molecular weight one (MW approximately 900) was conducted. This study proves that the Kinetex column packed with 2.6 microm shell particles is worthy of rivaling to sub-2 microm columns and other commercially available shell-type packings (Ascentis Express or Halo), both for small and large molecule separation. The Kinetex column offers a very flat C term. Utilizing this feature, high flow rates can be applied to accomplish very fast separations without significant loss in efficiency. Copyright 2010 Elsevier B.V. All rights reserved.

Development and validation of LC methods for the separation of misoprostol related substances and diastereoisomers.

PubMed

Kahsay, Getu; Song, Huiying; Eerdekens, Fran; Tie, Yaxin; Hendriks, Danny; Van Schepdael, Ann; Cabooter, Deirdre; Adams, Erwin

2015-01-01

Misoprostol is a synthetic prostaglandin E1 analogue which is mainly used for prevention and treatment of gastric ulcers, but also for abortion due to its labour inducing effect. Misoprostol exists as a mixture of diastereoisomers (1:1) and has several related impurities owing to its instability at higher temperatures and moisture. A simple and robust reversed phase liquid chromatographic (RPLC) method is described for the separation of the related substances and a normal phase (NP) LC method for the separation of misoprostol diastereoisomers. The RPLC method was performed using an Ascentis Express C18 (150 mm × 4.6 mm, 5 μm) column kept at 35 °C. The mobile phase was a gradient mixture of mobile phase A (ACN-H2O-MeOH, 28:69:3 v/v/v) and mobile phase B (ACN-H2O-MeOH, 47:50:3 v/v/v) eluted at a flow rate of 1.5 mL/min. UV detection was performed at 200 nm. The NPLC method was undertaken by using an XBridge bare silica (150 mm × 2.1 mm, 3.5 μm) column at 35 °C. The mobile phase contained 1-propanol-heptane-TFA (4:96:0.1%, v/v/v), pumped at a flow rate of 0.5 mL/min. UV detection was performed at 205 nm. This LC method can properly separate the two diastereoisomers (Rs > 2) within an analysis time of less than 20 min. Both methods were validated according to the ICH guidelines. Furthermore, these new LC methods have been successfully applied for purity control and diastereoisomers ratio determination of misoprostol bulk drug, tablets and dispersion. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of GC stationary phases for the separation of fatty acid methyl esters in biodiesel fuels.

PubMed

Goding, Julian C; Ragon, Dorisanne Y; O'Connor, Jack B; Boehm, Sarah J; Hupp, Amber M

2013-07-01

The fatty acid methyl ester (FAME) content of biodiesel fuels has traditionally been determined using gas chromatography with a polar stationary phase. In this study, a direct comparison of the separation of FAMEs present in various biodiesel samples on three polar stationary phases and one moderately polar stationary phase (with comparable column dimensions) was performed. Retention on each column was based on solubility in and polarity of the phase. Quantitative metrics describing the resolution of important FAME pairs indicate high resolution on all polar columns, yet the best resolution, particularly of geometric isomers, is achieved on the cyanopropyl column. In addition, the separation of four C18 monounsaturated isomers was optimized and the elution order determined on each column. FAME composition of various biodiesel fuel types was determined on each column to illustrate (1) chemical differences in biodiesels produced from different feedstocks and (2) chemical similarities in biodiesels of the same feedstock type produced in different locations and harvest seasons.

Two-column sequential injection chromatography--new approach for fast and effective analysis and its comparison with gradient elution chromatography.

PubMed

Chocholous, Petr; Satínský, Dalibor; Sklenárová, Hana; Solich, Petr

2010-05-23

This work presents novel approach in low-pressure chromatography flow systems--two-column Sequential Injection Chromatography (2-C SIC) and its comparison with gradient elution chromatography on the same instrument. The system was equipped with two different chromatographic columns (connected to selection valve in parallel design) for isocratic separation and determination of all components in composed anti-inflammatory pharmaceutical preparation (tablets). The sample was first injected on the first column of length 30 mm where less retained analytes were separated and then the sample was injected on the second column of length 10 mm where more retained analytes were separated. The SIC system was based on a commercial SIChrom manifold (8-port high-pressure selection valve and medium-pressure syringe pump with 4 mL reservoir) (FIAlab, USA) with two commercially available monolithic columns the "first column" Chromolith Flash RP-18e (25 mm x 4.6 mm i.d. with guard column 5 mm x 4.6 mm i.d.) and the "second column" Chromolith RP-18e (10 mm x 4.6 mm i.d.) and CCD UV-vis detector USB 4000 with micro-volume 1.0 cm Z flow cell. Two mobile phases were used for analysis (one for each column). The mobile phase 1 used for elution of paracetamol, caffeine and salicylic acid (internal standard) was acetonitrile/water (10:90, v/v, the water part of pH 3.5 adjusted with acetic acid), flow rate was 0.9 mL min(-1) (volume 3.0 mL of mobile phase per analysis). The mobile phase 2 used for elution of propyphenazone was acetonitrile/water (30:70, v/v); flow rate was 1.2 mL min(-1) (volume 1.5 mL of mobile phase per analysis). Absorbance was monitored at 210 nm. Samples were prepared by dissolving of one tablet in 30% acetonitrile and 10 microL of filtered supernatant was injected on each column (2 x 10 microL). The chromatographic resolution between all compounds was >1.45 and analysis time was 5.5 min under the optimal conditions. Limits of detection were determined at 0.4 microg mL(-1) for paracetamol, at 0.5 microg mL(-1) for caffeine and at 0.7 microg mL(-1) for propyphenazone. The new two-column chromatographic set-up developed as an alternative approach to gradient elution chromatography shows evident advantages (time and solvent reduction more than one-third) as compared with single-column gradient SIC method with Chromolith Flash RP-18 (25 mm x 4.6 mm i.d. with guard column 5 mm x 4.6 mm i.d.). Copyright 2010 Elsevier B.V. All rights reserved.

Two complementary reversed-phase separations for comprehensive coverage of the semipolar and nonpolar metabolome.

PubMed

Naser, Fuad J; Mahieu, Nathaniel G; Wang, Lingjue; Spalding, Jonathan L; Johnson, Stephen L; Patti, Gary J

2018-02-01

Although it is common in untargeted metabolomics to apply reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) methods that have been systematically optimized for lipids and central carbon metabolites, here we show that these established protocols provide poor coverage of semipolar metabolites because of inadequate retention. Our objective was to develop an RPLC approach that improved detection of these metabolites without sacrificing lipid coverage. We initially evaluated columns recently released by Waters under the CORTECS line by analyzing 47 small-molecule standards that evenly span the nonpolar and semipolar ranges. An RPLC method commonly used in untargeted metabolomics was considered a benchmarking reference. We found that highly nonpolar and semipolar metabolites cannot be reliably profiled with any single method because of retention and solubility limitations of the injection solvent. Instead, we optimized a multiplexed approach using the CORTECS T3 column to analyze semipolar compounds and the CORTECS C 8 column to analyze lipids. Strikingly, we determined that combining these methods allowed detection of 41 of the total 47 standards, whereas our reference RPLC method detected only 10 of the 47 standards. We then applied credentialing to compare method performance at the comprehensive scale. The tandem method showed more than a fivefold increase in credentialing coverage relative to our RPLC benchmark. Our results demonstrate that comprehensive coverage of metabolites amenable to reversed-phase separation necessitates two reconstitution solvents and chromatographic methods. Thus, we suggest complementing HILIC methods with a dual T3 and C 8 RPLC approach to increase coverage of semipolar metabolites and lipids for untargeted metabolomics. Graphical abstract Analysis of semipolar and nonpolar metabolites necessitates two reversed-phase chromatography (RPLC) methods, which extend metabolome coverage more than fivefold for untargeted profiling. HILIC hydrophilic interaction liquid chromatography.

Ionic liquid phases with comprehensive two-dimensional gas chromatography of fatty acid methyl esters.

PubMed

Pojjanapornpun, Siriluck; Nolvachai, Yada; Aryusuk, Kornkanok; Kulsing, Chadin; Krisnangkura, Kanit; Marriott, Philip J

2018-02-17

New generation inert ionic liquid (iIL) GC columns IL60i, IL76i and IL111i, comprising phosphonium or imidazolium cationic species, were investigated for separation of fatty acid methyl esters (FAME). In general, the iIL phases provide comparable retention times to their corresponding conventional columns, with only minor selectivity differences. The average tailing factors and peak widths were noticeably improved (reduced) for IL60i and IL76i, while they were slightly improved for IL111i. Inert IL phase columns were coupled with conventional IL columns in comprehensive two-dimensional GC (GC × GC) with a solid-state modulator which offers variable modulation temperature (T M ), programmable T M during analysis and trapping stationary phase material during the trap/release (modulation) process, independent of oven T and column sets. Although IL phases are classified as polar, relative polarity of the two phases comprising individual GC × GC column sets permits combination of less-polar IL/polar IL and polar IL/less-polar IL column sets; it was observed that a polar/less-polar column set provided better separation of FAME. A higher first dimension ( 1 D) phase polarity combined with a lower 2 D phase polarity, for instance 1 D IL111i with 2 D IL59 gave the best result; the greater difference in 1 D/ 2 D phase polarity results in increasing occupancy of peak area in the 2D space. The IL111i/IL59 column set was selected for analysis of fatty acids in fat and oil products (butter, margarine, fish oil and canola oil). Compared with the conventional IL111, IL111i showed reduced column bleed which makes this more suited to GC × GC analysis of FAME. The proposed method offers a fast profiling approach with good repeatability of analysis of FAME.

Separating methane emissions from agricultural sources and natural gas: direct measurements of excess columns of CH4, C2H6 and NH3 in the Colorado Front Range

NASA Astrophysics Data System (ADS)

Kille, N.; Chiu, R.; Frey, M.; Hase, F.; Kumar Sha, M.; Blumenstock, T.; Hannigan, J. W.; Volkamer, R. M.

2017-12-01

Methane (CH4) is a major greenhouse gas emitted from biogenic, thermogenic, and pyrogenic sources. Here we demonstrate a novel approach to separate sources of CH4 emissions based on a network of small portable sensors performing column measurements in the Northern Colorado Front Range (NCFR). In the study area CH4 is emitted from biogenic sources such as concentrated animal feeding operations (CAFOs) and natural gas production and storage. In March 2015 we deployed a network of five Fourier Transform Spectrometers (FTS) to characterize the regional scale methane dome in Colorado's Denver-Julesburg Basin based on excess vertical column measurements (the column enhancement inside the dome over background). Three EM27sun FTS measured CH4, oxygen (O2) and water vapor (H2O) columns at Eaton, CO (inside the dome) and at two boundary sites; the CU mobile SOF (Solar Occultation Flux) measured ethane (C2H6), ammonia (NH3), and H2O at Eaton, CO. The column averaged dry air mole fractions XCH4, XC2H6, and XNH3 were determined using O2 columns for air mass factor normalization, and background column was subtracted to derive excess vertical columns of DXCH4, DXC2H6, DXNH3 at Eaton, CO. Eaton is located both near CAFOs and at the northern edge of oil and natural gas production wells. Our approach for source apportioning methane employs a linear regression analysis that explains DXCH4 in terms of DXC2H6 as tracer for natural gas sources, and DXNH3 as tracer for CAFO emissions. The results of the source apportionment are compared with literature values of the NH3/CH4 and C2H6/CH4 ratio to evaluate the method of excess columns, which is independent of boundary layer height.

Quantitative determination of triterpene saponins and alkenated-phenolics from Labisia pumila using LC-UV/ELSD method and confirmation by LC-ESI-TOF

USDA-ARS?s Scientific Manuscript database

This study describes the first analytical method for the determination of saponins and alkenated-phenolics from the leaves, leaves/stems and roots of Labisia pumila using a HPLC-UV-ELSD method. The separation was achieved using a reversed phase column, PDA and ELS detection, and a water/acetonitrile...

Quantitative determination of triperpene saponins and alkenated-phenolics from Labisia pumila using LC-UV/ELSD method and confirmation by LC-ESI-TOF

USDA-ARS?s Scientific Manuscript database

This study describes the first analytical method for the determination of saponins and alkenated-phenolics from the leaves, leaves/stems and roots of Labisia pumila using a HPLC-UV-ELSD method. The separation was achieved using a reversed phase column, PDA and ELS detection, and a water/acetonitrile...

Analysis of benzo(a)pyrene in airborne particulates by gas chromatography

NASA Technical Reports Server (NTRS)

Luedecke, E.

1976-01-01

A routine method was developed to measure benzo(a)pyrene in airborne particulates. Samples were collected on a filter and the organic portion was extracted with cyclohexane. The polynuclear hydrocarbon (PNHC) fraction was separated from the aliphatics by column chromatography. An internal standard was added to the extract and a portion of it was injected into a gas chromatograph. Although the gas chromatographic method has often been reported in the literature, satisfactory separation of benzo(a)pyrene and benzo(e)pyrene has not been achieved. With the introduction of a nematic liquid crystal as the stationary phase good separation is now possible.

Application of a simple column-switching ion chromatography technique for removal of matrix interferences and sensitive fluorescence determination of acidic compounds (pharmaceutical drugs) in complex samples.

PubMed

Muhammad, Nadeem; Subhani, Qamar; Wang, Fenglian; Guo, Dandan; Zhao, Qiming; Wu, Shuchao; Zhu, Yan

2017-09-15

This work illustrates the introduction of a simple, rugged and flexible column-switching ion chromatography (IC) technique for an automated on-line QuEChERS extracted samples extracts washing followed by sensitive fluorescence (FLD) determination of five acidic pharmaceutical drugs namely; clofibric acid (CLO), ibuprofen (IBU), aspirin (ASP), naproxen (NAP) and flurobrofen (FLU) in three complex samples (spinach, apple and hospital sewage sludge). An old anion exchange column IonPac ® AS11-HC was utilized as a pre-treatment column for on-line washing of inorganic and organic interferences followed by isocratic separation of five acidic drugs with another anion exchange IonPac ® AS12A analytical column by exploiting the column-switching technique. This novel method exhibited good linearity with correlation coefficients (r 2 ) for all drugs were in the range 0.976-0.996. The limit of detection and quantification of all five acidic drugs were in the range 0.024μg/kg to 8.70μg/kg and 0.082μg/kg to 0.029mg/kg, respectively, and better recoveries in the range 81.17-112.5% with percentage relative standard deviations (RSDs) less than 17.8% were obtained. This on-line sample pre-treatment method showed minimum matrix effect in the range of 0.87-1.25 except for aspirin. This simple rugged and flexible column-switching system required only 28min for maximum elimination of matrices and interferences in three complex samples extracts, isocratic separation of five acidic drugs and for the continuous regeneration of pre-treatment column prior to every subsequent analysis. Finally, this simple automated IC system was appeared so rugged and flexible, which can eliminate and wash out most of interference, impurities and matrices in complex samples, simply by adjusting the NaOH and acetonitrile concentration in washing mobile phase with maximum recoveries of acidic analytes of interest. Copyright © 2017. Published by Elsevier B.V.

Preparation, characterization, and performance evaluation of UiO-66 analogues as stationary phase in HPLC for the separation of substituted benzenes and polycyclic aromatic hydrocarbons

PubMed Central

Yan, Zengguang; Li, Jianrong; Xie, Yabo; Bai, Liping; Jiang, Lin; Li, Fasheng

2017-01-01

UiO-66 analogues are good candidates as stationary phase in HPLC because of their chemical/thermal stability, large surface area, and two cage structures. Here, two UiO-66 analogues, UiO-66-NH2 and UiO-67, were synthesized and used as stationary phase in HPLC to evaluate their performance in the separation of substituted benzenes (SBs) and polycyclic aromatic hydrocarbons (PAHs). The results showed that SBs could be well separated on UiO-66-NH2 column but not on UiO-67 column. Nonetheless, PAHs could be well separated on UiO-67 column. The separation mechanisms of SBs and PAHs on UiO-66 analogues may be involved in the pore size and functional group in the frameworks of UiO-66 analogues. Introduction of the–NH2 into UiO-66 significantly reduced its adsorption capacity for SB congeners, which resulted in less separation of SBs on UiO-66-NH2. As for the separation of PAHs on UiO-67 column, the π-π stacking effect was supposed to play a vital role. PMID:28582453

Preparation, characterization, and performance evaluation of UiO-66 analogues as stationary phase in HPLC for the separation of substituted benzenes and polycyclic aromatic hydrocarbons.

PubMed

Zhao, Weiwei; Zhang, Chaoyan; Yan, Zengguang; Zhou, Youya; Li, Jianrong; Xie, Yabo; Bai, Liping; Jiang, Lin; Li, Fasheng

2017-01-01

UiO-66 analogues are good candidates as stationary phase in HPLC because of their chemical/thermal stability, large surface area, and two cage structures. Here, two UiO-66 analogues, UiO-66-NH2 and UiO-67, were synthesized and used as stationary phase in HPLC to evaluate their performance in the separation of substituted benzenes (SBs) and polycyclic aromatic hydrocarbons (PAHs). The results showed that SBs could be well separated on UiO-66-NH2 column but not on UiO-67 column. Nonetheless, PAHs could be well separated on UiO-67 column. The separation mechanisms of SBs and PAHs on UiO-66 analogues may be involved in the pore size and functional group in the frameworks of UiO-66 analogues. Introduction of the-NH2 into UiO-66 significantly reduced its adsorption capacity for SB congeners, which resulted in less separation of SBs on UiO-66-NH2. As for the separation of PAHs on UiO-67 column, the π-π stacking effect was supposed to play a vital role.

Tunnel frit: a nonmetallic in-capillary frit for nanoflow ultra high-performance liquid chromatography-mass spectrometryapplications.

PubMed

Chen, Chao-Jung; Chen, Wei-Yun; Tseng, Mei-Chun; Chen, Yet-Ran

2012-01-03

In this study, an easy method to fabricate a durable in-capillary frit was developed for use in nanoflow liquid chromatography (nanoLC). A small orifice was tunneled into the sol-gel frit during the polymerization process resulting in the simple fabrication of a tunnel frit. A short packing tunnel frit column (2 cm, C(18) particles) was able to sustain over 10,000 psi continuous liquid flow for 10 days without observation of particle loss, and back pressure variation was less than 5%. The tunnel frit was successfully applied to the fabrication of nanoflow ultra high-performance liquid chromatography (nano-UHPLC) trap and analytical columns. In the analysis of tryptic peptides, the tunnel frit trap and analytical columns were demonstrated to have high separation efficiency and sensitivity. In analysis of phosphopeptides, the use of the nonmetallic tunnel frit column showed better sensitivity than the metallic frit column. This design can facilitate the preparation of nano-HPLC and nano-UHPLC columns and the packing material can easily be refilled when the column is severely contaminated or clogged. © 2011 American Chemical Society

Simultaneous analysis of tea catechins, caffeine, gallic acid, theanine and ascorbic acid by micellar electrokinetic capillary chromatography.

PubMed

Aucamp, J P; Hara, Y; Apostolides, Z

2000-04-21

A micellar electrokinetic capillary chromatography (MEKC) method for the simultaneous analysis of five tea catechins, theanine, caffeine, gallic acid and ascorbic acid has been developed. The catechins are (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate. p-Nitrophenol serves as both reference and internal standard. All the components are separated within 13 min with a 57 cm uncoated fused-silica column. On-column detection was carried out at 200 nm. This method has been used to measure these compounds in fresh tea leaves and tea liquor. The limit of detection for all analytes ranged from 1 to 20 microg/ml.

Centrifugal precipitation chromatography

PubMed Central

Ito, Yoichiro; Lin, Qi

2009-01-01

Centrifugal precipitation chromatography separates analytes according their solubility in ammonium sulfate (AS) solution and other precipitants. The separation column is made from a pair of long spiral channels partitioned with a semipermeable membrane. In a typical separation, concentrated ammonium sulfate is eluted through one channel while water is eluted through the other channel in the opposite direction. The countercurrent process forms an exponential AS concentration gradient through the water channel. Consequently, protein samples injected into the water channel is subjected to a steadily increasing AS concentration and at the critical AS concentration they are precipitated and deposited in the channel bed by the centrifugal force. Then the chromatographic separation is started by gradually reducing the AS concentration in the AS channel which lowers the AS gradient concentration in the water channel. This results in dissolution of deposited proteins which are again precipitated at an advanced critical point as they move through the channel. Consequently, proteins repeat precipitation and dissolution through a long channel and finally eluted out from the column in the order of their solubility in the AS solution. The present method has been successfully applied to a number of analytes including human serum proteins, recombinant ketosteroid isomerase, carotenoid cleavage enzymes, plasmid DNA, polysaccharide, polymerized pigments, PEG-protein conjugates, etc. The method is capable to single out the target species of proteins by affinity ligand or immunoaffinity separation. PMID:19541553

Glycolipid class profiling by packed-column subcritical fluid chromatography.

PubMed

Deschamps, Frantz S; Lesellier, Eric; Bleton, Jean; Baillet, Arlette; Tchapla, Alain; Chaminade, Pierre

2004-06-18

The potential of packed-column subcritical fluid chromatography (SubFC) for the separation of lipid classes has been assessed in this study. Three polar stationary phases were checked: silica, diol, and poly(vinyl alcohol). Carbon dioxide (CO2) with methanol as modifier was used as mobile phase and detection performed by evaporative light scattering detection. The influence of methanol content, temperature, and pressure on the chromatographic behavior of sphingolipids and glycolipids were investigated. A complete separation of lipid classes from a crude wheat lipid extract was achieved using a modifier gradient from 10 to 40% methanol in carbon dioxide. Solute selectivity was improved using coupled silica and diol columns in series. Because the variation of eluotropic strength depending on the fluid density changes, a normalized separation factor product (NSP) was used to select the nature, the number and the order of the columns to reach the optimum glycolipid separation.

Preparation of a poly(styrene-co-DPHA-co-EDMA) monolith and its application for the separation of small molecules and biomacromolecules by HPLC.

PubMed

Wang, Xixi; Li, Xueying; Jiang, Xiaoya; Dong, Peipei; Liu, Haiyan; Bai, Ligai; Yan, Hongyuan

2017-04-01

A high performance liquid chromatography (HPLC) monolithic column was prepared by redox polymerization of styrene, dipentaerythritol hexaacrylate (DPHA) and ethylene glycol dimethacrylate (EDMA) in a porogen system of n-propanol/PEG400. The monolith was characterized by scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and the results indicated that the monolith had a stable and homogeneous structure. The porosity of the monolithic column was 75.86% and average pore diameter was 2.1µm. Several alkylbenzenes and anilines were used to evaluate the column performance in terms of hydrophobicity. Then the column was applied to separate small molecules including phytosterol and BSA tryptic digest. Finally, five standard proteins, egg white and plasma were separated respectively and high separation capacity of protein was obtained. Copyright © 2016 Elsevier B.V. All rights reserved.

"Supermarket Column Chromatography of Leaf Pigments" Revisited: Simple and Ecofriendly Separation of Plant Carotenoids, Chlorophylls, and Flavonoids from Green and Red Leaves

ERIC Educational Resources Information Center

Dias, Alice M.; Ferreira, Maria La Salete

2015-01-01

A simple and ecofriendly procedure was developed in order to prepare extracts from red and green leaves. This procedure enables the separation of yellow, green, and red band pigments and optimizes the previously reported baking soda "supermarket column". The same extract also led to a novel and colorful potato starch column, which can…

Spectrofluorometry, thin layer chromatography, and column high-performance liquid chromatography determination of rabeprazole sodium in the presence of its acidic and oxidized degradation products.

PubMed

Osman, Afaf Osman; Osman, Afaf; Osman, Mohamed

2009-01-01

The objective of this study is to develop validated stability-indicating spectrofluorometric, TLC-densitometric, and HPLC methods for the determination of rabeprazole sodium and its degradation products. The first method was based on measuring the fluorescence intensity of the drug at 416 and 311 nm for the emission and at 320 and 274 nm for the excitation for acid and oxidized solutions, respectively. The second method was based on the separation of the drug from its acidic and oxidized degradation products followed by densitometric measurement of the intact drug spot at 284 nm. The separation was carried out on Fluka TLC sheets of silica gel 60 F254 using isopropyl alcohol--30% ammonia (80 + 2, v/v) mobile phase. The third method was based on HPLC separation of rabeprazole sodium from its acidic and oxidized degradation products on a reversed-phase Waters Nova-Pak C18 column using 0.05 M potassium dihydrogen phosphate-methanol-acetonitrile (5 + 3 + 2, v/v/v) pH 7 +/- 0.2 mobile phase. The proposed procedures were successfully applied for the determination of rabeprazole sodium in pure form, laboratory-prepared mixtures, tablet, and expired batch. The obtained results were statistically compared with those of a reported method and validated according to United States Pharmacopeia guidelines. Two main acidic degradation products of the drug were separated and subjected to IR spectrometry and MS to confirm their structures, and the schemes for their formation were elucidated.

Acylhydrazone bond dynamic covalent polymer gel monolithic column online coupling to high-performance liquid chromatography for analysis of sulfonamides and fluorescent whitening agents in food.

PubMed

Zhang, Chengjiang; Luo, Xialin; Wei, Tianfu; Hu, Yufei; Li, Gongke; Zhang, Zhuomin

2017-10-13

A new dynamic covalent polymer (DCP) gel was well designed and constructed based on imine chemistry. Polycondensation of 4,4'-biphenyldicarboxaldehyde and 1,3,5-benzenetricarbohydrazide via Schiff-base reaction resulted in an acylhydrazone bond gel (AB-gel) DCP. AB-gel DCP had three-dimensional network of interconnected nanoparticles with hierarchically porous structure. AB-gel DCP was successfully fabricated as a monolithic column by an in-situ chemical bonding method for online enrichment and separation purpose with excellent permeability. AB-gel DCP based monolithic column showed remarkable adsorption affinity towards target analytes including sulfonamides (SAs) and fluorescent whitening agents (FWAs) due to its strong π-π affinity, hydrophobic effect and hydrogen bonding interaction. Then, AB-gel DCP based monolithic column was applied for online separation and analysis of trace SAs and FWAs in food samples coupled with high-performance liquid chromatography (HPLC). Sulfathiazole (ST) and sulfadimidine (SM2) in one positive weever sample were actually found and determined with concentrations of 273.8 and 286.3μg/kg, respectively. 2,5-Bis(5-tert-butyl-2-benzoxazolyl) thiophene (FWA184) was actually quantified in one tea infusion sample with the concentration of 268.5ng/L. The spiked experiments suggested the good recoveries in range of 74.5-110% for SAs in weever and shrimp samples with relative standard deviations (RSDs) less than 9.7% and in range of 74.0-113% for FWAs in milk and tea infusion samples with RSDs less than 9.0%. AB-gel DCP monolithic column was proved to be a promising sample preparation medium for online separation and analysis of trace analytes in food samples with complex matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Method of recovering adsorbed liquid compounds from molecular sieve columns

DOEpatents

Burkholder, H.R.; Fanslow, G.E.

1983-12-20

Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed. 8 figs.

Method of recovering adsorbed liquid compounds from molecular sieve columns

DOEpatents

Burkholder, Harvey R.; Fanslow, Glenn E.

1983-01-01

Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed.

Rapid, direct determination of polyphenols in tea by reversed-phase column liquid chromatography.

PubMed

Ding, M; Yang, H; Xiao, S

1999-07-23

Column liquid chromatography on a C18-bonded silica column with water-methanol-acetic acid as eluent was used to determine polyphenols and caffeine in tea. Without any pretreatment, catechin, epicatechin gallate, epigallocatechin gallate, epigallocatechin, epicatechin and caffeine were separated successfully within 15 min. The detection limits (S/N = 3) of polyphenols studied were 1.8-24 mg/l at a detection wavelength 270 nm. The linear range of the peak area calibration curves for the analytes were over two orders of magnitude with a correlation coefficient of 0.996-0.999. Using this method, some Chinese tea samples were analyzed with a good reproducibility (RSD are below 5%).

Scale-up protein separation on stainless steel wide bore toroidal columns in the type-J counter-current chromatography.

PubMed

Guan, Yue Hugh; Hewitson, Peter; van den Heuvel, Remco N A M; Zhao, Yan; Siebers, Rick P G; Zhuang, Ying-Ping; Sutherland, Ian

2015-12-11

Manufacturing high-value added biotech biopharmaceutical products (e.g. therapeutic proteins) requires quick-to-develop, GMP-compliant, easy-to-scale and cost effective preparatory chromatography technologies. In this work, we describe the construction and testing of a set of 5-mm inner diameter stainless steel toroidal columns for use on commercially available preparatory scale synchronous J-type counter-current chromatography (CCC) machinery. We used a 20.2m long column with an aqueous two-phase system containing 14% (w/w) PEG1000 and 14% (w/w) potassium phosphate at pH 7, and tested a sample loading of 5% column volume and a mobile phase flow rate of 20ml/min. We then satisfactorily demonstrated the potential for a weekly protein separation and preparation throughput of ca. 11g based on a normal weekly routine for separating a pair of model proteins by making five stacked injections on a single portion of stationary phase with no stripping. Compared to our previous 1.6mm bore PTFE toroidal column, the present columns enlarged the nominal column processing throughput by nearly 10. For an ideal model protein injection modality, we observed a scaling up factor of at least 21. The 2 scales of protein separation and purification steps were realized on the same commercial CCC device. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation of a novel dual-function strong cation exchange/hydrophobic interaction chromatography stationary phase for protein separation.

PubMed

Zhao, Kailou; Yang, Li; Wang, Xuejiao; Bai, Quan; Yang, Fan; Wang, Fei

2012-08-30

We have explored a novel dual-function stationary phase which combines both strong cation exchange (SCX) and hydrophobic interaction chromatography (HIC) characteristics. The novel dual-function stationary phase is based on porous and spherical silica gel functionalized with ligand containing sulfonic and benzyl groups capable of electrostatic and hydrophobic interaction functionalities, which displays HIC character in a high salt concentration, and IEC character in a low salt concentration in mobile phase employed. As a result, it can be employed to separate proteins with SCX and HIC modes, respectively. The resolution and selectivity of the dual-function stationary phase were evaluated under both HIC and SCX modes with standard proteins and can be comparable to that of conventional IEC and HIC columns. More than 96% of mass and bioactivity recoveries of proteins can be achieved in both HIC and SCX modes, respectively. The results indicated that the novel dual-function column could replace two individual SCX and HIC columns for protein separation. Mixed retention mechanism of proteins on this dual-function column based on stoichiometric displacement theory (SDT) in LC was investigated to find the optimal balance of the magnitude of electrostatic and hydrophobic interactions between protein and the ligand on the silica surface in order to obtain high resolution and selectivity for protein separation. In addition, the effects of the hydrophobicity of the ligand of the dual-function packings and pH of the mobile phase used on protein separation were also investigated in detail. The results show that the ligand with suitable hydrophobicity to match the electrostatic interaction is very important to prepare the dual-function stationary phase, and a better resolution and selectivity can be obtained at pH 6.5 in SCX mode. Therefore, the dual-function column can replace two individual SCX and HIC columns for protein separation and be used to set up two-dimensional liquid chromatography with a single column (2DLC-1C), which can also be employed to separate three kinds of active proteins completely, such as lysozyme, ovotransferrin and ovalbumin from egg white. The result is very important not only to the development of new 2DLC technology with a single column for proteomics, but also to recombinant protein drug production for saving column expense and simplifying the process in biotechnology. Copyright © 2012 Elsevier B.V. All rights reserved.

Microchip electrospray: improvements in spray and signal stability during gradient elution by an inverted postcolumn makeup flow.

PubMed

Jung, Stephanie; Effelsberg, Uwe; Tallarek, Ulrich

2011-12-01

Dynamic changes in mobile phase composition during high-performance liquid chromatography (HPLC) gradient elution coupled to mass spectrometry (MS) sensitively affect electrospray modes. We investigate the impact of the eluent composition on spray stability and MS response by infusion and injection experiments with a small tetrapeptide in water-acetonitrile mixtures. The employed HPLC/electrospray (ESI)-MS configuration uses a microchip equipped with an enrichment column, a separation column, and a makeup flow (MUF) channel. One nano pump is connected to the separation column, while a second one delivers solvent of exactly inverted composition to the MUF channel. Both solvent streams are united behind the separation column, before the ESI tip, such that the resulting electrosprayed solution always has identical composition during a gradient elution. Analyte peak parameters without and with MUF compensation are determined and discussed with respect to the electrospray mode and eluent composition. The postcolumn MUF significantly improves spray and signal stability over the entire solvent gradient, without compromising the performance of the HPLC separation column. It can also be conveniently implemented on microchip platforms.

Fabrication and investigation of electrochromatographic columns with a simplex configuration.

PubMed

Liu, Qing; Yang, Lijun; Wang, Qiuquan; Zhang, Bo

2014-07-04

Duplex capillary columns with a packed and an open section are widely used in electrochromatography (CEC). The duplex column configuration leads to non-uniform voltage drop, electrical field distribution and separation performance. It also adds to the complexity in understanding and optimizing electrochromatographic process. In this study, we introduced a simplex column configuration based on single particle fritting technology. The new column configuration has an essentially uniform packed bed through the entire column length, with only 1mm length left unpacked serving as the optical detection window. The study shows that a simplex column has higher separation efficiency than a duplex column, especially at the high voltage range, due to the consistent distribution of electrical field over the column length. In comparison to the duplex column, the simplex column presented a lower flow rate at the same applied voltage, suggesting that an open section may support a higher speed than a packed section. In practice, the long and short ends of the simplex column could be used as independent CEC columns respectively. This "two-in-one" bi-functional column configuration provided extra flexibilities in selecting and optimizing electrochromatographic conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Constant pressure-assisted head-column field-amplified sample injection in combination with in-capillary derivatization for enhancing the sensitivity of capillary electrophoresis.

PubMed

Yan, Na; Zhou, Lei; Zhu, Zaifang; Zhang, Huige; Zhou, Ximin; Chen, Xingguo

2009-05-15

In this work, a novel method combining constant pressure-assisted head-column field-amplified sample injection (PA-HC-FASI) with in-capillary derivatization was developed for enhancing the sensitivity of capillary electrophoresis. PA-HC-FASI uses an appropriate positive pressure to counterbalance the electroosmotic flow in the capillary column during electrokinetic injection, while taking advantage of the field amplification in the sample matrix and the water of the "head column". Accordingly, the analytes were stacked at the stationary boundary between water and background electrolyte. After 600s PA-HC-FASI, 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatization reagent was injected, followed by an electrokinetic step (5kV, 45s) to enhance the mixing efficiency of analytes and reagent plugs. Standing a specified time of 10min for derivatization reaction under 35 degrees C, then the capillary temperature was cooled to 25 degrees C and the derivatives were immediately separated and determined under 25 degrees C. By investigating the variables of the presented approach in detail, on-line preconcentration, derivatization and separation could be automatically operated in one run and required no modification of current CE commercial instrument. Moreover, the sensitivity enhancement factor of 520 and 800 together with the detection limits of 16.32 and 6.34pg/mL was achieved for model compounds: glufosinate and aminomethylphosphonic acid, demonstrating the high detection sensitivity of the presented method.

Sub-to super-ambient temperature programmable microfabricated gas chromatography column

DOEpatents

Robinson, Alex L.; Anderson, Lawrence F.

2004-03-16

A sub- to super-ambient temperature programmable microfabricated gas chromatography column enables more efficient chemical separation of chemical analytes in a gas mixture by combining a thermoelectric cooler and temperature sensing on the microfabricated column. Sub-ambient temperature programming enables the efficient separation of volatile organic compounds and super-ambient temperature programming enables the elution of less volatile analytes within a reasonable time. The small heat capacity and thermal isolation of the microfabricated column improves the thermal time response and power consumption, both important factors for portable microanalytical systems.

Rotating Apparatus for Isoelectric Focusing

NASA Technical Reports Server (NTRS)

Bier, M.

1986-01-01

Remixing of separated fractions prevented. Improved isoelectric focusing apparatus helps to prevent electro-osmosis and convection, both of which cause remixing of separated fractions. Fractionating column segmented and rotated about horizontal axis: Only combined effects of both features fully effective in making good separations. Improved apparatus slowly rotated continuously or rocked (at rotational amplitude of at least 180 degrees) about its horizontal axis so average gravitational vector experienced by fluid is zero and convection is therefore suppressed. Electro-osmosis suppressed and convection further suppressed by separating column into disklike compartments along its length with filters. Experiments have shown dimensions of apparatus not critical. Typical compartment and column volumes are 2 and 40 ml, respectively. Rotation speeds lie between 3 and 30 rpm.

A narrow open tubular column for high efficiency liquid chromatographic separation.

PubMed

Chen, Huang; Yang, Yu; Qiao, Zhenzhen; Xiang, Piliang; Ren, Jiangtao; Meng, Yunzhu; Zhang, Kaiqi; Juan Lu, Joann; Liu, Shaorong

2018-04-30

We report a great feature of open tubular liquid chromatography when it is run using an extremely narrow (e.g., 2 μm inner diameter) open tubular column: more than 10 million plates per meter can be achieved in less than 10 min and under an elution pressure of ca. 20 bar. The column is coated with octadecylsilane and both isocratic and gradient separations are performed. We reveal a focusing effect that may be used to interpret the efficiency enhancement. We also demonstrate the feasibility of using this technique for separating complex peptide samples. This high-resolution and fast separation technique is promising and can lead to a powerful tool for trace sample analysis.

INTERIOR VIEW OF FILTER/DRYERS USED TO FILTER OUT AND SEPARATE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

INTERIOR VIEW OF FILTER/DRYERS USED TO FILTER OUT AND SEPARATE BICARBONATE FROM AMMONIONATED BRINE. DISCHARGE FROM STRIPPER COLUMNS (SOLVAY COLUMNS). - Solvay Process Company, SA Wetside Building, Between Willis & Milton Avenue, Solvay, Onondaga County, NY

HILIC separation mechanisms of tetracyclines on amino bonded silica column

USDA-ARS?s Scientific Manuscript database

Effects of mobile phase variations on the chromatographic separation on amino bonded silica column in hydrophilic interaction chromatography (HILIC) were investigated for four zwitterionic tetracyclines (TCs): oxytetracycline, doxycycline, chlortetracycline and tetracycline. A mixed-mode retention m...

Separation technologies for the recovery and dehydration of alcohols from fermentation broths

EPA Science Inventory

Multi-column distillation followed by molecular sieve adsorption is currently the standard method for producing fuel grade ethanol from dilute fermentation broths in modern corn-to-ethnol facilities. As the liquid biofuels industry transitions to lignocellulosic feedstocks, expan...

Chromatographic test methods for characterizing alkylsiloxane-bonded silica columns for reversed-phase liquid chromatography.

PubMed

Poole, Colin F

2018-06-07

Major obstacles to formulating a simple retention mechanism for reversed-phase liquid chromatography have a direct impact on the development of experimental methods for column characterization as they limit our capability to understand observed differences in retention at a system level. These problems arise from the heterogeneous composition of the stationary phase, the difficulty of providing a working definition for the phase ratio, and uncertainty as to whether the distribution mechanism for varied compounds is a partition, adsorption or mixed (combination) of these models. Retention factor and separation factor measurements offer little guidance as they represent an average of various and variable contributing factors that can only be interpreted by assuming a specific model. Column characterization methods have tended to ignore these difficulties by inventing a series of terms to describe column properties, such as hydrophobicity, hydrophilicity, silanol activity, steric resistance, etc., without proper definition. This has allowed multiple scales to be proposed for the same property which generally are only weakly correlated. Against this background we review the major approaches for the characterization of alkylsiloxane-bonded silica stationary phases employing prototypical compounds, the hydrophobic-subtraction model and the solvation parameter model. Those methods using prototypical compounds are limited by the lack of compounds with a singular dominant interaction. The multivariate approaches that extract column characteristic properties from the retention of varied compounds are more hopeful but it is important to be more precise in defining the characteristic column properties and cognizant that general interpretation of these properties for varied columns cannot escape the problem of a poor understanding of the distribution mechanism. Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous liquid chromatographic determination of metals and organic compounds in pharmaceutical and food-supplement formulations using evaporative light scattering detection.

PubMed

Spacil, Zdenek; Folbrova, Jana; Megoulas, Nikolaos; Solich, Petr; Koupparis, Michael

2007-02-05

A novel method for the non-derivatization liquid chromatographic determination of metals (potassium, aluminium, calcium and magnesium) and organic compounds (ascorbate and aspartate) was developed and validated based on evaporative light scattering detection (ELSD). Separation of calcium, magnesium and aluminium was achieved by the cation exchange column Dionex CS-14 and an aqueous TFA mobile phase according to the following time program: 0-6 min TFA 0.96 mL L(-1), 6-7 min linear gradient from TFA 0.96-6.4 mL L(-1). Separation of potassium, magnesium and aspartate was achieved by the lipophilic C18 Waters Spherisorb column and isocratic aqueous 0.2 mL L(-1) TFA mobile phase. Separation of sodium, magnesium, ascorbate and citrate was also achieved by the C18 analytical column, according to the following elution program: 0-2.5 min aqueous nonafluoropentanoic acid (NFPA) 0.5 mL L(-1); 2.5-3.5 min linear gradient from 0.5 mL L(-1) NFPA to 1.0 mL L(-1) TFA. In all cases, evaporation temperature was 70 degrees C, pressure of the nebulizing gas (nitrogen) 3.5 bar, gain 11 and the flow rate 1.0 mL min(-1). Resolution among calcium and magnesium was 1.8, while for all other separations was > or = 3.2. Double logarithmic calibration curves were obtained within various ranges from 3-24 to 34-132 microg mL(-1), and with good correlation (r>0.996). Asymmetry factor ranged from 0.9 to 1.9 and limit of detection from 1.3 (magnesium) to 17 microg mL(-1) (ascorbate). The developed method was applied for the assay of potassium, magnesium, calcium, aluminium, aspartate and ascorbate in pharmaceuticals and food-supplements. The accuracy of the method was evaluated using spiked samples (%recovery 95-105%, %R.S.D. < 2) and the absence of constant or proportional errors was confirmed by dilution experiments.

Advantages of core-shell particle columns in Sequential Injection Chromatography for determination of phenolic acids.

PubMed

Chocholouš, Petr; Vacková, Jana; Srámková, Ivana; Satínský, Dalibor; Solich, Petr

2013-01-15

Currently, for Sequential Injection Chromatography (SIC), only reversed phase C18 columns have been used for chromatographic separations. This article presents the first use of three different stationary phases: three core-shell particle-packed reversed phase columns in flow systems. The aim of this work was to extend the chromatographic capabilities of the SIC system. Despite the particle-packed columns reaching system pressures of ≤ 610 PSI, their conditions matched those of a commercially produced and optimised SIC system (SIChrom™ (FIAlab(®), USA)) with a 8-port high-pressure selection valve and medium-pressure Sapphire™ syringe pump with a 4 mL reservoir and maximum system pressure of ≤ 1000 PSI. The selectivity of each of the tested columns, Ascentis(®) Express RP-Amide, Ascentis(®) Express Phenyl-Hexyl and Ascentis(®) Express C18 (30 mm × 4.6mm, core-shell particle size 2.7 μm), was compared by their ability to separate seven phenolic acids that are secondary metabolite substances widely distributed in plants. The separations of all of the components were performed by isocratic elution using binary mobile phases composed of acetonitrile and 0.065% phosphoric acid at pH 2.4 (a specific ratio was used for each column) at a flow-rate of 0.60 mL/min. The volume of the mobile phase was 3.8 mL for each separation. The injection volume of the sample was 10 μL for each separation. The UV detection wavelengths were set to 250, 280 and 325 nm. The RP-Amide column provided the highest chromatographic resolution and allowed for complete baseline separation of protocatechuic, syringic, vanillic, ferulic, sinapinic, p-coumaric and o-coumaric acids. The Phenyl-Hexyl and C18 columns were unable to completely separate the tested mixture, syringic and vanillic acid and ferulic and sinapinic acids could not be separated from one another. The analytical parameters were a LOD of 0.3 mg L(-1), a LOQ of 1.0 mg L(-1), a calibration range of 1.0-50.0 (100.0) mg L(-1) (r>0.997) and a system precision of 10 mg L(-1) with a RSD ≤ 1.65%. The high performance of the chromatography process with the RP-Amide column under optimised conditions was highlighted and well documented (HETP values ≤ 10 μm, peak symmetry ≤ 1.33, resolution ≥ 1.87 and time for one analysis <8.0 min). The results of these experiments confirmed the benefits of extending chromatographic selectivity using core-shell particle column technology in a SIC manifold. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of monolithic and microparticulate columns for reversed-phase liquid chromatography of tryptic digests of industrial enzymes in cleaning products.

PubMed

Beneito-Cambra, M; Herrero-Martínez, J M; Ramis-Ramos, G; Lindner, W; Lämmerhofer, M

2011-10-14

Enzymes of several classes used in the formulations of cleaning products were characterized by trypsin digestion followed by HPLC with UV detection. A polymeric monolithic column (ProSwift) was used to optimize the separation of both the intact enzymes and their tryptic digests. This column was adequate for the quality control of raw industrial enzyme concentrates. Then, monolithic and microparticulate columns were compared for peptide analysis. Under optimized conditions, the analysis of tryptic digests of enzymes of different classes commonly used in the formulation of cleaning products was carried out. Number of peaks, peak capacity and global resolution were obtained in order to evaluate the chromatographic performance of each column. Particulate shell-core C18 columns (Kinetex, 2.6 μm) showed the best performance, followed by a silica monolithic column (Chromolith RP-18e) and the conventional C18 packings (Gemini, 5 μm or 3 μm). A polymeric monolithic column (ProSwift) gave the worst performances. The proposed method was satisfactorily applied to the characterization of the enzymes present in spiked detergent bases and commercial cleaners. Copyright © 2011 Elsevier B.V. All rights reserved.

Possibilities and limitations of the kinetic plot method in supercritical fluid chromatography.

PubMed

De Pauw, Ruben; Desmet, Gert; Broeckhoven, Ken

2013-08-30

Although supercritical fluid chromatography (SFC) is becoming a technique of increasing importance in the field of analytical chromatography, methods to compare the performance of SFC-columns and separations in an unbiased way are not fully developed. The present study uses mathematical models to investigate the possibilities and limitations of the kinetic plot method in SFC as this easily allows to investigate a wide range of operating pressures, retention and mobile phase conditions. The variable column length (L) kinetic plot method was further investigated in this work. Since the pressure history is identical for each measurement, this method gives the true kinetic performance limit in SFC. The deviations of the traditional way of measuring the performance as a function of flow rate (fixed back pressure and column length) and the isopycnic method with respect to this variable column length method were investigated under a wide range of operational conditions. It is found that using the variable L method, extrapolations towards other pressure drops are not valid in SFC (deviation of ∼15% for extrapolation from 50 to 200bar pressure drop). The isopycnic method provides the best prediction but its use is limited when operating closer towards critical point conditions. When an organic modifier is used, the predictions are improved for both methods with respect to the variable L method (e.g. deviations decreases from 20% to 2% when 20mol% of methanol is added). Copyright © 2013 Elsevier B.V. All rights reserved.

[Analysis of monosaccharides and uronic acids in polysaccharides by pre-column derivatization with p-aminobenzoic acid and high performance liquid chromatography].

PubMed

Hao, Guitang; Chen, Shangwei; Zhu, Song; Yin, Hongping; Dai, Jun; Cao, Yuhua

2007-01-01

An ion-pair reversed-phase high performance liquid chromatographic (RP-HPLC) method for the simultaneous determination of carbohydrate and uronic acids was developed. p-Aminobenzoic acid (p-AMBA) was used for pre-column derivatization of the analytes, enabling fluorescence (lambda(ex) = 313 nm, lambda(em) = 358 nm) or ultraviolet (UV at 303 nm) detection. Reaction conditions such as reaction temperature and reaction time were optimized. Atlantis dC18 column with hydrophilic end capping was selected for the separation of derivatives. Effects of mobile phase compositions such as ion pairs and their concentrations and pH on the retention behaviors and separation results of 9 monosaccharides and 2 uronic acids were investigated. Derivatives of fructose, galactose, glucose, mannose, xylose, arabinose, ribose, galacturonic acid, fucose, glucuronic acid and rhamnose were separated within 42 min, applying tetrabutyl ammonium hydrogen bisulfate (TBAHSO4) as the ion pair reagent. The detection limits were between 3.38 x 10(-8) mol/L and 176 x 10(-8) mol/L for fluorescence detection and between 2.55 x 10(-7) mol/L and 13.4 x 10(-7) mol/L for UV detection. Good linearities were obtained with correlation coefficients (r2) above 0.99. The relative standard deviations (RSDs) of the peak area of the derivatives in 12 - 51 h after derivatization were from 2.5% to 3.9%. This method has been applied for the determination of mono-/disaccharides and uronic acids in spirulina polysaccharide after dissolved in trifluoroacetic acid solution (2 mol/L). The results showed this method is suitable for the analysis of monosaccharide compositions in polysaccharides.

Commander prepares glass columns for electrophoresis experiment

NASA Technical Reports Server (NTRS)

1982-01-01

Commander Jack Lousma prepares on of the glass columns for the electrophoresis test in the middeck area of the Columbia. The experiment, deployed in an L-shaped mode in upper right corner, consists of the processing unit with glass columns in which the separation takes place; a camera (partially obscurred by Lousma's face) to document the process; and a cryogenic freezer to freeze and store the samples after separation.

Evaluation of a hydrophilic interaction liquid chromatography design space for sugars and sugar alcohols.

PubMed

Hetrick, Evan M; Kramer, Timothy T; Risley, Donald S

2017-03-17

Based on a column-screening exercise, a column ranking system was developed for sample mixtures containing any combination of 26 sugar and sugar alcohol analytes using 16 polar stationary phases in the HILIC mode with acetonitrile/water or acetone/water mobile phases. Each analyte was evaluated on the HILIC columns with gradient elution and the subsequent chromatography data was compiled into a statistical software package where any subset of the analytes can be selected and the columns are then ranked by the greatest separation. Since these analytes lack chromophores, aerosol-based detectors, including an evaporative light scattering detector (ELSD) and a charged aerosol detector (CAD) were employed for qualitative and quantitative detection. Example qualitative applications are provided to illustrate the practicality and efficiency of this HILIC column ranking. Furthermore, the design-space approach was used as a starting point for a quantitative method for the trace analysis of glucose in trehalose samples in a complex matrix. Knowledge gained from evaluating the design-space led to rapid development of a capable method as demonstrated through validation of the following parameters: specificity, accuracy, precision, linearity, limit of quantitation, limit of detection, and range. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Liu, Ying

My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were ablemore » to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic resolution, high column stability, and high sensitivity. In addition, this method showed potential usefulness for the sensitive and quick analysis of hydrolysis products of polysaccharides, and for trace level analysis of individual oligosaccharides or oligosaccharide isomers from biological systems.« less

Automated two-dimensional interface for capillary gas chromatography

DOEpatents

Strunk, M.R.; Bechtold, W.E.

1996-02-20

A multidimensional gas chromatograph (GC) system is disclosed which has wide bore capillary and narrow bore capillary GC columns in series and has a novel system interface. Heart cuts from a high flow rate sample, separated by a wide bore GC column, are collected and directed to a narrow bore GC column with carrier gas injected at a lower flow compatible with a mass spectrometer. A bimodal six-way valve is connected with the wide bore GC column outlet and a bimodal four-way valve is connected with the narrow bore GC column inlet. A trapping and retaining circuit with a cold trap is connected with the six-way valve and a transfer circuit interconnects the two valves. The six-way valve is manipulated between first and second mode positions to collect analyte, and the four-way valve is manipulated between third and fourth mode positions to allow carrier gas to sweep analyte from a deactivated cold trap, through the transfer circuit, and then to the narrow bore GC capillary column for separation and subsequent analysis by a mass spectrometer. Rotary valves have substantially the same bore width as their associated columns to minimize flow irregularities and resulting sample peak deterioration. The rotary valves are heated separately from the GC columns to avoid temperature lag and resulting sample deterioration. 3 figs.

Automated two-dimensional interface for capillary gas chromatography

DOEpatents

Strunk, Michael R.; Bechtold, William E.

1996-02-20

A multidimensional gas chromatograph (GC) system having wide bore capillary and narrow bore capillary GC columns in series and having a novel system interface. Heart cuts from a high flow rate sample, separated by a wide bore GC column, are collected and directed to a narrow bore GC column with carrier gas injected at a lower flow compatible with a mass spectrometer. A bimodal six-way valve is connected with the wide bore GC column outlet and a bimodal four-way valve is connected with the narrow bore GC column inlet. A trapping and retaining circuit with a cold trap is connected with the six-way valve and a transfer circuit interconnects the two valves. The six-way valve is manipulated between first and second mode positions to collect analyte, and the four-way valve is manipulated between third and fourth mode positions to allow carrier gas to sweep analyte from a deactivated cold trap, through the transfer circuit, and then to the narrow bore GC capillary column for separation and subsequent analysis by a mass spectrometer. Rotary valves have substantially the same bore width as their associated columns to minimize flow irregularities and resulting sample peak deterioration. The rotary valves are heated separately from the GC columns to avoid temperature lag and resulting sample deterioration.

Synthesis of a mixed-model stationary phase derived from glutamine for HPLC separation of structurally different biologically active compounds: HILIC and reversed-phase applications.

PubMed

Aral, Tarık; Aral, Hayriye; Ziyadanoğulları, Berrin; Ziyadanoğulları, Recep

2015-01-01

A novel mixed-mode stationary phase was synthesised starting from N-Boc-glutamine, aniline and spherical silica gel (4 µm, 60 Å). The prepared stationary phase was characterized by IR and elemental analysis. The new stationary phase bears an embedded amide group into phenyl ring, highly polar a terminal amide group and non-polar groups (phenyl and alkyl groups). At first, this new mixed-mode stationary phase was used for HILIC separation of four nucleotides and five nucleosides. The effects of different separation conditions, such as pH value, mobile phase and temperature, on the separation process were investigated. The optimum separation for nucleotides was achieved using HILIC isocratic elution with aqueous mobile phase and acetonitrile with 20°C column temperature. Under these conditions, the four nucleotides could be separated and detected at 265 nm within 14 min. Five nucleosides were separated under HILIC isocratic elution with aqueous mobile phase containing pH=3.25 phosphate buffer (10mM) and acetonitrile with 20°C column temperature and detected at 265 nm within 14 min. Chromatographic parameters as retention factor, selectivity, theoretical plate number and peak asymmetry factor were calculated for the effect of temperature and water content in mobile phase on the separation process. The new column was also tested for nucleotides and nucleosides mixture and six analytes were separated in 10min. The chromatographic behaviours of these polar analytes on the new mixed-model stationary phase were compared with those of HILIC columns under similar conditions. Further, phytohormones and phenolic compounds were separated in order to see influence of the new stationary phase in reverse phase conditions. Eleven plant phytohormones were separated within 13 min using RP-HPLC gradient elution with aqueous mobile phase containing pH=2.5 phosphate buffer (10mM) and acetonitrile with 20°C column temperature and detected at 230 or 278 nm. The best separation conditions for seven phenolic compounds was also achieved using reversed-phase HPLC gradient elution with aqueous mobile phase containing pH=2.5 phosphate buffer (10mM) and acetonitrile with 20°C column temperature and seven phenolic compounds could be separated and detected at 230 nm within 16 min. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous analysis of C1 and C4 oxidized oligosaccharides, the products of lytic polysaccharide monooxygenases acting on cellulose.

PubMed

Westereng, Bjørge; Arntzen, Magnus Ø; Aachmann, Finn L; Várnai, Anikó; Eijsink, Vincent G H; Agger, Jane Wittrup

2016-05-06

Lytic polysaccharide monooxygenases play a pivotal role in enzymatic deconstruction of plant cell wall material due to their ability to catalyze oxidative cleavage of glycosidic bonds. LPMOs may release different products, often in small amounts, with various oxidation patterns (C1 or C4) and with varying stabilities, making accurate analysis of product profiles a major challenge. So far, HPAEC has been the method of choice but it has limitations with respect to analysis of C4-oxidized products. Here, we compare various HPLC methods and present procedures that allow efficient separation of intact C1- and C4-oxidized products. We demonstrate that both PGC and HILIC (in WAX-mode) can separate C1- and C4-oxidized products and that PGC gives superior chromatographic performance. In contrast to HPAEC, these methods are directly compatible with mass spectroscopy and charged aerosol detection (CAD), which enables online peak validation and quantification with LOD levels in the low ng range. While the novel methods show lower resolution than HPAEC, this is compensated by easy peak identification, allowing, for example, discrimination between chromatographically highly similar native and C4-oxidized cello-oligomers. HPAEC-MS studies revealed chemical oxidation of C4-geminal diol products, which implies that peaks commonly believed to be C4-oxidized cello-oligomers, in fact are on-column generated derivatives. Non-destructive separation of C4-oxidized cello-oligosaccharides on the PGC column allowed us, for the first time, to isolate C4-oxidized standards. HPAEC fractionation of a purified C4-oxidized tetramer revealed that on-column decomposition leads to formation of the native trimer, which may explain why product mixtures generated by C4-oxidizing LPMOs seem to be rich in native oligosaccharides when analyzed by HPAEC. The findings and methods described here will aid in future studies in the emerging LPMO field. Copyright © 2016 Elsevier B.V. All rights reserved.

Automation of nanoflow liquid chromatography-tandem mass spectrometry for proteome analysis by using a strong cation exchange trap column.

PubMed

Jiang, Xiaogang; Feng, Shun; Tian, Ruijun; Han, Guanghui; Jiang, Xinning; Ye, Mingliang; Zou, Hanfa

2007-02-01

An approach was developed to automate sample introduction for nanoflow LC-MS/MS (microLC-MS/MS) analysis using a strong cation exchange (SCX) trap column. The system consisted of a 100 microm id x 2 cm SCX trap column and a 75 microm id x 12 cm C18 RP analytical column. During the sample loading step, the flow passing through the SCX trap column was directed to waste for loading a large volume of sample at high flow rate. Then the peptides bound on the SCX trap column were eluted onto the RP analytical column by a high salt buffer followed by RP chromatographic separation of the peptides at nanoliter flow rate. It was observed that higher performance of separation could be achieved with the system using SCX trap column than with the system using C18 trap column. The high proteomic coverage using this approach was demonstrated in the analysis of tryptic digest of BSA and yeast cell lysate. In addition, this system was also applied to two-dimensional separation of tryptic digest of human hepatocellular carcinoma cell line SMMC-7721 for large scale proteome analysis. This system was fully automated and required minimum changes on current microLC-MS/MS system. This system represented a promising platform for routine proteome analysis.

Intermittent simulated moving bed chromatography: 3. Separation of Tröger's base enantiomers under nonlinear conditions.

PubMed

Katsuo, Shigeharu; Langel, Christian; Sandré, Anne-Laure; Mazzotti, Marco

2011-12-30

One of the modified simulated moving bed (SMB) processes, the intermittent SMB (I-SMB) process, has been recently analyzed theoretically [1] and its superior performance compared to the conventional SMB process has been demonstrated at a rather low total feed concentration through experiments and simulations [2]. This work shows that the I-SMB process outperforms the conventional SMB process also at high feed concentration where the species are clearly subject to a nonlinear adsorption isotherm. In the case of the separation of the Tröger's base's enantiomers in ethanol on ChiralPak AD, the two processes operated in a six-column 1-2-2-1 configuration (one column in sections 1 and 4 and two columns in sections 2 and 3) and in a four-column 1-1-1-1 configuration (one column in each section) are compared at high feed concentration through both experiments and simulations. Even under nonlinear conditions the four column I-SMB process can successfully separate the two enantiomers achieving purity levels as high as the two six column processes and exhibiting better productivity. Copyright © 2011 Elsevier B.V. All rights reserved.

Rapid preparative separation of monoclonal antibody charge variants using laterally-fed membrane chromatography.

PubMed

Sadavarte, Rahul; Madadkar, Pedram; Filipe, Carlos Dm; Ghosh, Raja

2018-01-15

Monoclonal antibodies undergo various forms of chemical transformation which have been shown to cause loss in efficacy and alteration in pharmacokinetic properties of these molecules. Such modified antibody molecules are known as variants. They also display physical properties such as charge that are different from intact antibody molecules. However, the difference in charge is very subtle and separation based on it is quite challenging. Charge variants are usually separated using ion-exchange column chromatography or isoelectric focusing. In this paper, we report a rapid and scalable method for fractionating monoclonal antibody charge variants, based on the use of cation exchange laterally-fed membrane chromatography (LFMC). Starting with a sample of monoclonal antibody hIgG1-CD4, three well-resolved fractions were obtained using either pH or salt gradient. These fractions were identified as acidic, neutral and basic variants. Each of these fractions contained intact heavy and light chains and so antibody fragmentation had no role in variant generation. The separation was comparable to that using column chromatography but was an order of magnitude faster. Copyright © 2017 Elsevier B.V. All rights reserved.

Diamondoid Characterization in Condensate by Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry: The Junggar Basin of Northwest China

PubMed Central

Li, Shuifu; Hu, Shouzhi; Cao, Jian; Wu, Ming; Zhang, Dongmei

2012-01-01

Diamondoids in crude oil are useful for assessing the maturity of oil in high maturation. However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil. In this paper, we use comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) to study the compounds in condensates from the Junggar Basin of northwest China and address their geological and geochemical applications. GC×GC-TOFMS improves the resolution and separation efficiency of the compounds. It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)). A reversed-phase column system improves the separation capabilities over the normal phase column system. The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%. PMID:23109861

Enantiomers Recognition of Propranolol Based on Organic-Inorganic Hybrid Open-Tubular MIPs-CEC Column Using 3-(Trimethoxysilyl)Propyl Methacrylate as a Cross-Linking Monomer.

PubMed

Chen, Guo-Ning; Li, Ning; Luo, Tian; Dong, Yu-Ming

2017-04-01

In this study, 3-(trimethoxysilyl)propyl methacrylate (γ-MPS), a bifunctional group compound, was used as a single cross-linking agent to prepare molecular imprinted inorganic-organic hybrid polymers by in situ polymerization for open-tubular capillary electro chromatography (CEC) column. The optimal preparation conditions were: the ratio between template molecule and functional monomer was 1:4; the volume proportion of porogen toluene and methanol was 1:1 and the volume of cross-linking agent γ-MPS was 69 μL. The optimal separation conditions were separation voltage of 15 kV; detection wavelength at 215 nm and background electrolyte composed of 70% acetonitrile/20 mmol/L boric acid salt (pH 6.9). Under the optimized conditions, the propranolol enantiomers can be separated well by CEC. The method is simple and fast, it can be a potentially useful approach for propranolol enantiomers separation. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

High-resolution separation of neodymium and dysprosium ions utilizing extractant-impregnated graft-type particles.

PubMed

Uchiyama, Shoichiro; Sasaki, Takaaki; Ishihara, Ryo; Fujiwara, Kunio; Sugo, Takanobu; Umeno, Daisuke; Saito, Kyoichi

2018-01-19

An efficient method for rare metal recovery from environmental water and urban mines is in high demand. Toward rapid and high-resolution rare metal ion separation, a novel bis(2-ethylhexyl) phosphate (HDEHP)-impregnated graft-type particle as a filler for a chromatography column is proposed. To achieve rapid and high-resolution separation, a convection-flow-aided elution mode is required. The combination of 35 μm non-porous particles and a polymer-brush-rich particle structure minimizes the distance from metal ion binding sites to the convection flow in the column, resulting in minimized diffusional mass transfer resistance and the convection-flow-aided elution mode. The HDEHP-impregnated graft-type non-porous-particle-packed cartridge developed in this study exhibited a higher separation performance for model rare metals, neodymium (III) and dysprosium (III) ions, and a narrower peak at a higher linear velocity, than those of previous HDEHP-impregnated fiber-packed and commercially available Lewatit ® VP OC 1026-packed cartridges. Copyright © 2017 Elsevier B.V. All rights reserved.

Isolation and identification of arctiin and arctigenin in leaves of burdock (Arctium lappa L.) by polyamide column chromatography in combination with HPLC-ESI/MS.

PubMed

Liu, Shiming; Chen, Kaoshan; Schliemann, Willibald; Strack, Dieter

2005-01-01

A simple method involving polyamide column chromatography in combination with HPLC-PAD and HPLC-ESI/MS for isolating and identifying two kinds of lignans, arctiin and arctigenin, in the leaves of burdock (Arctium lappa L.) has been established. After extraction of burdock leaves with 80% methanol, the aqueous phase of crude extracts was partitioned between water and chloroform and the aqueous phase was fractionated on a polyamide glass column. The fraction, eluting with 100% methanol, was concentrated and gave a white precipitate at 4 degrees C from which two main compounds were purified by semi-preparative HPLC. In comparison with the UV and ESI-MS spectra and the HPLC retention time of authentic standards, the compounds were determined to be arctiin and arctigenin. The extraction/separation technique was validated using an internal standard method.

HPLC column-switching technique for sample preparation and fluorescence determination of propranolol in urine using fused-core columns in both dimensions.

PubMed

Satínský, Dalibor; Havlíková, Lucie; Solich, Petr

2013-08-01

A new and fast high-performance liquid chromatography (HPLC) column-switching method using fused-core columns in both dimensions for sample preconcentration and determination of propranolol in human urine has been developed. On-line sample pretreatment and propranolol preconcentration were performed on an Ascentis Express RP-C-18 guard column (5 × 4.6 mm), particle size, 2.7 μm, with mobile phase acetonitrile/water (5:95, v/v) at a flow rate of 2.0 mL min(-1) and at a temperature of 50 °C. Valve switch from pretreatment column to analytical column was set at 4.0 min in a back-flush mode. Separation of propranolol from other endogenous urine compounds was achieved on the fused-core column Ascentis Express RP-Amide (100 × 4.6 mm), particle size, 2.7 μm, with mobile phase acetonitrile/water solution of 0.5% triethylamine, pH adjusted to 4.5 by means of glacial acetic acid (25:75, v/v), at a flow rate of 1.0 mL min(-1) and at a temperature of 50 °C. Fluorescence excitation/emission detection wavelengths were set at 229/338 nm. A volume of 1,500 μL of filtered urine sample solution was injected directly into the column-switching HPLC system. The total analysis time including on-line sample pretreatment was less than 8 min. The experimentally determined limit of detection of the method was found to be 0.015 ng mL(-1).

Determination of flavonoids and saponins in Gynostemma pentaphyllum (Thunb.) Makino by liquid chromatography-mass spectrometry.

PubMed

Kao, T H; Huang, S C; Inbaraj, B Stephen; Chen, B H

2008-09-26

Gynostemma pentaphyllum (Thunb.) Makino, a traditional Chinese herb possessing antitumor and antioxidant activities, has been shown to contain several functional components like saponins and flavonoids. However, their identities remain uncertain. The objectives of this study were to develop an appropriate extraction, purification and HPLC-MS method to determine saponins and flavonoids in G. pentaphyllum. Both flavonoids and saponins were extracted with methanol, followed by purification with a C18 cartridge to elute the former with 50% methanol and the latter with 100% methanol. A total of 34 saponins were separated within 40 min by a Gemini C18 column and a gradient mobile phase of acetonitrile and 0.1% formic acid in water, in which 18 saponins were identified by LC-MS with ESI mode and Q-TOF (LC/MS/MS). Similarly, a total of eight flavonoids were separated within 45 min by the same column and a gradient solvent system of methanol and 0.1% formic acid in water, with identification being carried out by a post-column derivatization method and LC-MS with ESI mode. The amounts of flavonoids in G. pentaphyllum ranged from 170.7 to 2416.5 mug g(-1), whereas saponins were from 491.0 to 89,888.9 mug g(-1).

Core-Shell in Liquid Chromatography: Application for Determining Sulphonamides in Feed and Meat Using Conventional Chromatographic Systems

PubMed Central

Armentano, Antonio; Summa, Simona; Magro, Sonia Lo; D’Antini, Pasquale; Palermo, Carmen; Muscarella, Marilena

2016-01-01

A C18 column packed with core-shell particles was used for the chromatographic separation of sulphonamides in feed and meat by a conventional high performance liquid chromatography system coupled with a diode array detector. Two analytical methods, already used in our laboratory, have been modified without any changes in the extraction and clean-up steps and in the liquid chromatography instrumentation. Chromatographic conditions applied on a traditional 5-µm column have been optimized on a column packed with 2.6 µm core-shell particles. A binary mobile phase [acetate buffer solution at pH 4.50 and a mixture of methanol acetonitrile 50: 50 (v/v)] was employed in gradient mode at the flow rate of 1.2 mL with an injection volume of 6 µL. These chromatographic conditions allow the separation of 13 sulphonamides with an entire run of 13 minutes. Preliminary studies have been carried out comparing blanks and spiked samples of feed and meat. A good resolution and the absence of interferences were achieved in chromatograms for both matrices. Since no change was made to the sample preparation, the optimized method does not require a complete revalidation and can be used to make routine analysis faster. PMID:28217560

Rapid determination of amino acids in biological samples using a monolithic silica column.

PubMed

Song, Yanting; Funatsu, Takashi; Tsunoda, Makoto

2012-05-01

A high-performance liquid chromatography method in which fluorescence detection is used for the simultaneous determination of 21 amino acids is proposed. Amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and then separated on a monolithic silica column (MonoClad C18-HS, 150 mm×3 mm i.d.). A mixture of 25 mM citrate buffer containing 25 mM sodium perchlorate (pH 5.5) and acetonitrile was used as the mobile phase. We found that the most significant factor in the separation was temperature, and a linear temperature gradient from 30 to 49°C was used to control the column temperature. The limits of detection and quantification for all amino acids ranged from 3.2 to 57.2 fmol and 10.8 to 191 fmol, respectively. The calibration curves for the NBD-amino acid had good linearity within the range of 40 fmol to 40 pmol when 6-aminocaproic acid was used as an internal standard. Using only conventional instruments, the 21 amino acids could be analyzed within 10 min. This method was found to be suitable for the quantification of the contents of amino acids in mouse plasma and adrenal gland samples.

Chaotropic salts in liquid chromatographic method development for the determination of pramipexole and its impurities following quality-by-design principles.

PubMed

Vemić, Ana; Rakić, Tijana; Malenović, Anđelija; Medenica, Mirjana

2015-01-01

The aim of this paper is to present a development of liquid chromatographic method when chaotropic salts are used as mobile phase additives following the QbD principles. The effect of critical process parameters (column chemistry, salt nature and concentration, acetonitrile content and column temperature) on the critical quality attributes (retention of the first and last eluting peak and separation of the critical peak pairs) was studied applying the design of experiments-design space methodology (DoE-DS). D-optimal design is chosen in order to simultaneously examine both categorical and numerical factors in minimal number of experiments. Two ways for the achievement of quality assurance were performed and compared. Namely, the uncertainty originating from the models was assessed by Monte Carlo simulations propagating the error equal to the variance of the model residuals and propagating the error originating from the model coefficients' calculation. The baseline separation of pramipexole and its five impurities is achieved fulfilling all the required criteria while the method validation proved its reliability. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of multiple quaternary ammonium compounds in the brain using tandem capillary column separation and high resolution mass spectrometric detection.

PubMed

Falasca, Sara; Petruzziello, Filomena; Kretz, Robert; Rainer, Gregor; Zhang, Xiaozhe

2012-06-08

Endogenous quaternary ammonium compounds are involved in various physiological processes in the central nervous system. In the present study, eleven quaternary ammonium compounds, including acetylcholine, choline, carnitine, acetylcarnitine and seven other acylcarnitines of low polarity, were analyzed from brain extracts using a two dimension capillary liquid chromatography-Fourier transform mass spectrometry method. To deal with their large difference in hydrophobicities, tandem coupling between reversed phase and hydrophilic interaction chromatography columns was used to separate all the targeted quaternary ammonium compounds. Using high accuracy mass spectrometry in selected ion monitoring mode, all the compounds could be detected from each brain sample with high selectivity. The developed method was applied for the relative quantification of these quaternary ammonium compounds in three different brain regions of tree shrews: prefrontal cortex, striatum, and hippocampus. The comparative analysis showed that quaternary ammonium compounds were differentially distributed across the three brain areas. The analytical method proved to be highly sensitive and reliable for simultaneous determination of all the targeted analytes from brain samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Fully automated multifunctional ultrahigh pressure liquid chromatography system for advanced proteome analyses

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

Lee, Jung Hwa; Hyung, Seok-Won; Mun, Dong-Gi

2012-08-03

A multi-functional liquid chromatography system that performs 1-dimensional, 2-dimensional (strong cation exchange/reverse phase liquid chromatography, or SCX/RPLC) separations, and online phosphopeptides enrichment using a single binary nano-flow pump has been developed. With a simple operation of a function selection valve, which is equipped with a SCX column and a TiO2 (titanium dioxide) column, a fully automated selection of three different experiment modes was achieved. Because the current system uses essentially the same solvent flow paths, the same trap column, and the same separation column for reverse-phase separation of 1D, 2D, and online phosphopeptides enrichment experiments, the elution time information obtainedmore » from these experiments is in excellent agreement, which facilitates correlating peptide information from different experiments.« less

APPLICATION OF A SPRAY DEPOSITION METHOD FOR REVERSED PHASE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

EPA Science Inventory

Four coal gasification wastewater samples were analyzed for nonvolatile and polar organics by liquid chromatography-mass spectrometry (LC/MS). Samples were separated on a reverse phase liquid chromatographic column using an aqueous solvent as the eluant. A special spray depositio...

Preparative Separation and Purification of the Total Flavonoids in Scorzonera austriaca with Macroporous Resins.

PubMed

Xie, Yang; Guo, Qiu-Shi; Wang, Guang-Shu

2016-06-13

The use of macroporous resins for the separation and purification of total flavonoids to obtain high-purity total flavonoids from Scorzonera austriaca was studied. The optimal conditions for separation and purification of total flavonoids in S. austriaca with macroporous resins were as follows: D4020 resin columns were loaded with crude flavonoid extract solution, and after reaching adsorptive saturation, the columns were eluted successively with 5 bed volumes (BV) of water, 5 BV of 5% (v/v) aqueous ethanol and 5 BV of 30% (v/v) aqueous ethanol at an elute flow rate of 2 BV·h(-1). Total flavonoids were obtained from the 30% aqueous ethanol eluate by vacuum distillation recovery. The content of flavonoid compounds in the total flavonoids was 93.5%, which represents an improvement by about 150%. In addition, five flavonoid compounds in the product were identified as 2″-O-β-d-xylopyranosyl isoorientin, 6-C-α-l-arabipyranosyl orientin, orientin, isoorientin and vitexin by LC-ESI-MS analysis and internal standard methods. The results in this study could represent a method for the large-scale production of total flavonoids from S. austriaca.

Analysis of pharmaceutical impurities using multi-heartcutting 2D LC coupled with UV-charged aerosol MS detection.

PubMed

Zhang, Kelly; Li, Yi; Tsang, Midco; Chetwyn, Nik P

2013-09-01

To overcome challenges in HPLC impurity analysis of pharmaceuticals, we developed an automated online multi-heartcutting 2D HPLC system with hyphenated UV-charged aerosol MS detection. The first dimension has a primary column and the second dimension has six orthogonal columns to enhance flexibility and selectivity. The two dimensions were interfaced by a pair of switching valves equipped with six trapping loops that allow multi-heartcutting of peaks of interest in the first dimension and also allow "peak parking." The hyphenated UV-charged aerosol MS detection provides comprehensive detection for compounds with and without UV chromophores, organics, and inorganics. It also provides structural information for impurity identification. A hidden degradation product that co-eluted with the drug main peak was revealed by RP × RP separation and thus enabled the stability-indicating method development. A poorly retained polar component with no UV chromophores was analyzed by RP × hydrophilic interaction liquid chromatography separation with charged aerosol detection. Furthermore, using this system, the structures of low-level impurities separated by a method using nonvolatile phosphate buffer were identified and tracked by MS in the second dimension. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Study on the analytical methods of catechins in tea and green tea polyphenol samples by high performance liquid chromatography].

PubMed

Dai, J; Wang, H X; Chen, S W; Tang, J

2001-09-01

Hypersil BDS C18 and Zorbax SB C18, suitable to separate simultaneously seven kinds of catechins and caffeine, were screened out from seven brands of reversed-phase columns. Mobile phase was a solution of methanol-water-acetic acid (or trifluoro acetic acid). Seven kinds of catechins in tea samples from six places in China and three green tea polyphenol(GTP) samples from different producers were separated and determined in 30 min by isocratic and gradient elutions. The effects of mobile phase components and temperature of column on retention parameters of catechins and caffeine are reviewed. Chromatographic conditions and pretreatment methods of samples were optimized. Gallocatechin gallate(GCG) and (-)-catechin gallate(CG) were identified by electrospray ionization mass spectrometry(ESI-MS) and prepared by high performance liquid chromatography for quantitative analysis. The other catechins, (-)-epigallocatechin (EGC), (+)-catechin (D-C), (-)-epicatechin(EC), (-)-epigallocatechin gallate(EGCG), (-)-epicatechin gallate(ECG) were identified with standards.

Deconvolution of gas chromatographic data

NASA Technical Reports Server (NTRS)

Howard, S.; Rayborn, G. H.

1980-01-01

The use of deconvolution methods on gas chromatographic data to obtain an accurate determination of the relative amounts of each material present by mathematically separating the merged peaks is discussed. Data were obtained on a gas chromatograph with a flame ionization detector. Chromatograms of five xylenes with differing degrees of separation were generated by varying the column temperature at selected rates. The merged peaks were then successfully separated by deconvolution. The concept of function continuation in the frequency domain was introduced in striving to reach the theoretical limit of accuracy, but proved to be only partially successful.

Integrated multiplexed capillary electrophoresis system

DOEpatents

Yeung, Edward S.; Tan, Hongdong

2002-05-14

The present invention provides an integrated multiplexed capillary electrophoresis system for the analysis of sample analytes. The system integrates and automates multiple components, such as chromatographic columns and separation capillaries, and further provides a detector for the detection of analytes eluting from the separation capillaries. The system employs multiplexed freeze/thaw valves to manage fluid flow and sample movement. The system is computer controlled and is capable of processing samples through reaction, purification, denaturation, pre-concentration, injection, separation and detection in parallel fashion. Methods employing the system of the invention are also provided.

Separation of polyethylene glycols and amino-terminated polyethylene glycols by high-performance liquid chromatography under near critical conditions.

PubMed

Wei, Y-Z; Zhuo, R-X; Jiang, X-L

2016-05-20

The separation and characterization of polyethylene glycols (PEGs) and amino-substituted derivatives on common silica-based reversed-phase packing columns using isocratic elution is described. This separation is achieved by liquid chromatography under the near critical conditions (LCCC), based on the number of amino functional end groups without obvious effect of molar mass for PEGs. The mobile phase is acetonitrile in water with an optimal ammonium acetate buffer. The separation mechanism of PEG and amino-substituted PEG under the near LCCC on silica-based packing columns is confirmed to be ion-exchange interaction. Under the LCCC of PEG backbone, with fine tune of buffer concentration, the retention factor ratios for benzylamine and phenol in buffered mobile phases, α(benzylamine/phenol)-values, were used to assess the ion-exchange capacity on silica-based reversed-phase packing columns. To the best of our knowledge, this is the first report on separation of amino-functional PEGs independent of the molar mass by isocratic elution using common C18 or phenyl reversed-phase packing columns. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of polymer monolithic column functionalized by arsonic acid groups for mixed-mode capillary liquid chromatography.

PubMed

Qin, Zhang-Na; Yu, Qiong-Wei; Wang, Ren-Qi; Feng, Yu-Qi

2018-04-27

A mixed-mode polymer monolithic column functionalized by arsonic acid groups was prepared by single-step in situ copolymerization of monomers p-methacryloylaminophenylarsonic acid (p-MAPHA) and pentaerythritol triacrylate (PETA). The prepared poly(p-MAPHA-co-PETA) monolithic column has a homogeneous monolithic structure with good permeability and mechanical stability. Zeta potential measurements reveal that the monolithic stationary phase holds a negative surface charge when the mobile phase resides in the pH range of 3.0-8.0. The retention mechanisms of prepared monolithic column are explored by the separation of selected polycyclic aromatic hydrocarbons (PAHs), nucleosides, and three basic compounds. The results indicate that the column functions in three different separation modes associated with reversed-phase chromatography based on hydrophobic interaction, hydrophilic interaction chromatography, and cation-exchange chromatography. The column efficiency of prepared monolithic column is estimated to be 70,000 and 76,000 theoretical plates/m for thiourea and naphthalene, respectively, at a linear flow velocity of 0.85 mm/s using acetonitrile/H 2 O (85/15, v/v) as the mobile phase. Furthermore, an analysis of the retention factors obtained for the PAHs indicates that the prepared monolithic column exhibits good reproducibility with relative standard deviations of 2.9%, 4.0%, and 4.7% based on run-to-run injections, column-to-column preparation, and batch-to-batch preparation, respectively. Finally, we investigate the separation performance of the proposed monolithic column for select phenols, sulfonamides, nucleobases and nucleosides. Copyright © 2018 Elsevier B.V. All rights reserved.

Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols.

PubMed

Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping

2015-05-01

Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences. Copyright © 2015 Elsevier B.V. All rights reserved.

Using the liquid nature of the stationary phase in countercurrent chromatography. IV. The cocurrent CCC method.

PubMed

Berthod, Alain; Hassoun, Mahmoud

2006-05-26

The retention volumes of solutes in countercurrent chromatography (CCC) are directly proportional to their distribution coefficients, K(D) in the biphasic liquid system used as mobile and stationary phase in the CCC column. The cocurrent CCC method consists in putting the liquid "stationary" phase in slow motion in the same direction as the mobile phase. A mixture of five steroid compounds of widely differing polarities was used as a test mixture to evaluate the capabilities of the method with the biphasic liquid system made of water/methanol/ethyl acetate/heptane 6/5/6/5 (v/v) and a 53 mL CCC column of the coil planet centrifuge type. It is shown that the chromatographic resolution obtained in cocurrent CCC is very good because the solute band broadening is minimized as long as the solute is located inside the "stationary" phase. Pushing the method at its limits, it is demonstrated that the five steroids can still be (partly) separated when the flow rate of the two liquid phases is the same (2 mL/min). This is due to the higher volume of upper phase (72% of the column volume) contained inside the CCC column producing a lower linear speed compared to the aqueous lower phase linear speed. The capabilities of the cocurrent CCC method compare well with those of the gradient elution method in HPLC. Continuous detection is a problem due to the fact that two immiscible liquid phases elute from the column. It was partly solved using an evaporative light scattering detector.

Two-dimensional gas chromatographic analysis of ambient light hydrocarbons.

PubMed

Liao, Wei-Chen; Ou-Yang, Cheng-Feng; Wang, Chieh-Heng; Chang, Chih-Chung; Wang, Jia-Lin

2013-06-14

Ambient level hydrocarbons lighter than C6 were analyzed by the Deans switch-modulated comprehensive two-dimensional gas chromatography (GC×GC) method with flame ionization detection (FID). A thermal desorption (TD) device built in-house connects the GC×GC system to pre-concentrate the target compounds at ambient levels prior to GC analysis. Because the conventional orthogonality based on polarity difference for normal GC×GC separation does not provide sufficient retention for the target compounds of extremely high volatility, the orthogonality of non-polar vs. adsorptive force was adopted instead. The system employed a 100% polydimethyl siloxane column serving as the first-dimension column to provide separation based on dispersive interaction, with a short PLOT column serving as the second-dimension column to provide the needed retention based on gas-solid adsorption interactions. The shortest possible length of the PLOT column was tested to minimize the modulation period (PM) and wraparound and, at the same time, to maintain the desired resolution. The tests led to the final optimal parameters of 1.1m for the PLOT column length, 9s for the PM, 0.013 for the modulation duty cycle (DC) and a modulation ratio (MR) of 3.7 with minimal wraparound. Important criteria for quality assurance of precision and linearity are reported. The low cost and ease of construction and operation make the in-house Deans switch TD-GC×GC-FID system practical and useful for the analysis of light hydrocarbons in urban or industrial environments. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation of amino acids and antibiotics by narrow-bore and normal-bore high-performance liquid chromatography with pre-column derivatization.

PubMed

Fiedler, H P; Plaga, A

1987-01-16

The selectivity, efficiency and lifetime of normal- and narrow-bore columns for high-performance liquid chromatography were investigated for the separation and quantification of amino acids and the amino acid-like antibiotics phosphinothricin and phosphinothricylalanylalanine in biological samples. These compounds were determined by an automated pre-column derivatization with o-phthalaldehyde-2-mercaptoethanol reagent and UV detection at 338 nm.

Separation and identification of neutral cereal lipids by normal phase high-performance liquid chromatography, using evaporative light-scattering and electrospray mass spectrometry for detection.

PubMed

Rocha, João M; Kalo, Paavo J; Ollilainen, Velimatti; Malcata, F Xavier

2010-04-30

A novel method was developed for the analysis of molecular species in neutral lipid classes, using separation by normal phase high-performance liquid chromatography, followed by detection by evaporative light-scattering and electrospray ionization tandem mass spectrometry. Monoacid standards, i.e. sterol esters, triacylglycerols, fatty acids, diacylglycerols, free sterols and monoacylglycerols, were separated to baseline on microbore 3 microm-silica gel columns. Complete or partial separation of molecular species in each lipid class permitted identification by automatic tandem mass spectrometry of ammonium adducts, produced via positive electrospray ionization. After optimization of the method, separation and identification of molecular species of various lipid classes was comprehensively tested by analysis of neutral lipids from the free lipid extract of maize flour. 2010 Elsevier B.V. All rights reserved.

An Efficient Method for Co-purification of Eggshell Matrix Proteins OC-17, OC-116, and OCX-36

PubMed Central

2016-01-01

In this study, we improved the eggshell-membrane separation process by separating the shell and membrane with EDTA solution, evaluating effects of three different extraction solutions (acetic acid, EDTA, and phosphate solution), and co-purifying multiple eggshell proteins with two successive ion-exchange chromatography procedures (CM Sepharose Fast Flow and DEAE Sepharose Fast Flow). The recovery and residual rates of eggshell and membrane separated by the modified method with added EDTA solution were 93.88%, 91.15% and 1.01%, 2.87%, respectively. Ovocleidin-116 (OC-116) and ovocalyxin-36 (OCX-36) were obtained by loading 50 mM Na-Hepes, pH 7.5, 2 mM DTT and 350 mM NaCl buffer onto the DEAE-FF column at a flow rate of 1 mL/min, ovocleidin-17 (OC-17) was obtained by loading 100 mM NaCl, 50 mM Tris, pH 8.0 on the CM-FF column at a flow rate of 0.5 mL/min. The purities of OCX-36, OC-17 and OC-116 were 96.82%, 80.15% and 73.22%, and the recovery rates were 55.27%, 53.38% and 36.34%, respectively. Antibacterial activity test suggested that phosphate solution extract exhibited significantly higher activity against the tested bacterial strains than the acetic acid or EDTA extract, probably due to more types of proteins in the extract. These results demonstrate that this separation method is feasible and efficient. PMID:28115888

Liquid Crystals in Chromatography

NASA Astrophysics Data System (ADS)

Witkiewicz, Zygfryd

The following sections are included: * INTRODUCTION * LIQUID CRYSTALS SUITABLE FOR GAS CHROMATOGRAPHY * Monomeric Liquid Crystal Stationary Phases * Polymeric Liquid Crystal Stationary Phases * Polymeric Liquid Crystal Stationary Phases * Conventional Analytical Columns * Capillary Columns * FACTORS AFFECTING THE CHROMATOGRAPHIC SEPARATIONS ON LIQUID CRYSTAL STATIONARY PHASES * Kind of Mesophase of the Liquid Crystal * Molecular Structure of the Liquid Crystals and of the Chromatographed Substances * Substrate on which the Liquid Crystal is Deposited * ANALYTICAL APPLICATIONS OF LIQUID CRYSTAL STATIONARY PHASES IN GAS CHROMATOGRAPHY * Separation of Isomers of Benzene and Naphthalene Derivatives * Separation of Alkane and Alkene Isomers * Separation of Mixtures of Benzene and Aliphatic Hydrocarbon Derivatives Containing Heteroatoms * Separation of Polynuclear Hydrocarbons * INVESTIGATION OF THE PROPERTIES OF LIQUID CRYSTALS BY GAS CHROMATOGRAPHY * APPLICATION OF LIQUID CRYSTALS IN LIQUID CHROMATOGRAPHY * Column Chromatography * Thin-Layer Chromatography * APPLICATION OF LIQUID CRYSTAL STATIONARY PHASES IN SUPERCRITICAL FLUID CHROMATOGRAPHY * FINAL REMARKS * References

Preparative separation and purification of rosmarinic acid from perilla seed meal via combined column chromatography.

PubMed

Tang, Weizhuo; Sun, Baoshan; Zhao, Yuqing

2014-02-01

In this study, the preparative separation and purification of rosmarinic acid (RA) from perilla seed meal (PSM), which is a by-product of edible oil production, was achieved using combined column chromatography over macroporous and polyamide resins. To optimize the RA enrichment process, the performance and separation characteristics of nine selected macroporous resins with different chemical and physical properties were investigated. SP825 resin was the most effective: the content of RA increased from 0.27% in the original extract to 16.58% in the 50% ethanol fraction (a 61.4-fold increase). During further purification treatment on polyamide resin, 90.23% pure RA could be obtained in the 70% ethanol fraction. RA with a higher purity (>95%) could also be easily obtained using one crystallization operation. The proposed method is simple, easily operated, cost-effective, and environmentally friendly and is suitable for both large-scale RA production and waste management. Copyright © 2013 Elsevier B.V. All rights reserved.

Study of Separation and Identification of the Active Ingredients in Gardenia jasminoides Ellis Based on a Two-Dimensional Liquid Chromatography by Coupling Reversed Phase Liquid Chromatography and Hydrophilic Interaction Liquid Chromatography.

PubMed

Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

2017-01-01

In this paper, by coupling reversed phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC), a two-dimensional liquid chromatography system was developed for separation and identification of the active ingredients in Gardenia jasminoides Ellis (GJE). By applying the semi-preparative C18 column as the first dimension and the core-shell column as the second dimension, a total of 896 peaks of GJE were separated. Among the 896 peaks, 16 active ingredients including geniposide, gardenoside, gardoside, etc. were identified by mass spectrometry analysis. The results indicated that the proposed two-dimensional RPLC/HILIC system was an effective method for the analysis of GJE and might hold a high potential to become a useful tool for analysis of other complex mixtures. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Separation of Uncharged Oligodeoxynucleotide Analogs by Anion-Exchange Chromatography at High pH

NASA Technical Reports Server (NTRS)

Schmidt, Jurgen G.; Nielsen, Peter E.; Orgel, Leslie

1996-01-01

Ion-exchange chromatography is a well-established method for the analysis and purification of phosphodiester-linked oligonucleotides. If elution is carried out under alkaline conditions, the secondary structure of G- and C-rich oligomers is disrupted. Furthermore, elution times become more sensitive to the G and T content of the oligomer, because G and T are deprotonated at pH 10. In recent work on peptide-nucleic acids (PNAs) we noted that mixtures of PNA oligomers G(sub 4), G(Sub 6), G(sub 8), and G(sub 10) are readily separated by elution at pH 12 on an RPC-5 column. Here we show that this separation method is more generally applicable.

Gas chromatographic separation of fatty acid methyl esters on weakly polar capillary columns.

PubMed

Yamamoto, Kouhei; Kinoshita, Akemi; Shibahara, Akira

2008-02-22

It was found that weakly polar columns, routinely used in capillary GC for analyzing sterols, food additives, etc., can also be used for separating fatty acid methyl esters (FAMEs). On these columns, FAMEs elute in the order of their unsaturation. The equivalent chain-length value of methyl 22:6 is below 23.00. This means FAMEs within a carbon chain length, having up to six double bonds, elute before the next (one carbon longer) saturated FAME elutes. Peak identification is easy. Weakly polar columns are compatible in both GC and GC/MS systems.

Supramolecular Affinity Chromatography for Methylation-Targeted Proteomics.

PubMed

Garnett, Graham A E; Starke, Melissa J; Shaurya, Alok; Li, Janessa; Hof, Fraser

2016-04-05

Proteome-wide studies of post-translationally methylated species using mass spectrometry are complicated by high sample diversity, competition for ionization among peptides, and mass redundancies. Antibody-based enrichment has powered methylation proteomics until now, but the reliability, pan-specificity, polyclonal nature, and stability of the available pan-specific antibodies are problematic and do not provide a standard, reliable platform for investigators. We have invented an anionic supramolecular host that can form host-guest complexes selectively with methyllysine-containing peptides and used it to create a methylysine-affinity column. The column resolves peptides on the basis of methylation-a feat impossible with a comparable commercial cation-exchange column. A proteolyzed nuclear extract was separated on the methyl-affinity column prior to standard proteomics analysis. This experiment demonstrates that such chemical methyl-affinity columns are capable of enriching and improving the analysis of methyllysine residues from complex protein mixtures. We discuss the importance of this advance in the context of biomolecule-driven enrichment methods.

An improved design of spiral tube assembly for separation of proteins by high-speed counter-current chromatography.

PubMed

Dasarathy, Dhweeja; Ito, Yoichiro

2015-10-30

A new spiral tube assembly was designed to improve the column capacity and partition efficiency for protein separation. This spiral tube assembly has greater column capacity than the original tubing because of an increase in radial grooves from 4 to 12 to accommodate more spiral layers and 12 narrow spots instead of 4 in each circular loop to interrupt the laminar flow that causes sample band broadening. Standard PTFE tubing (1.6mm ID) and the modified flat-twisted tubing were used as the separation column. The performances of both assemblies were compared for separating three stable test proteins including cytochrome c, myoglobin, and lysozyme using a two phase aqueous-aqueous solvent system composed of polyethylene glycol 1000 (12.5% w/w) and dibasic potassium phosphate (12.5% w/w). All samples were run at 1, 2, 3, and 5mL/min at both 800rpm and 1000rpm. The separation of these three protein samples produced high stationary phase retentions at 1, 2, and 3mL/min, yet separated efficiently at 5mL/min in 40min. After comparing the separation efficiency in terms of the peak resolutions, theoretical plate numbers, and separation times, it was determined that the flat-twisted tubing was more effective in separating these protein samples. In order to validate the efficacy of this novel assembly, a mixture of five protein samples (cytochrome c, myoglobin, ovalbumin, lysozyme, and hemoglobin) were separated, under the optimal conditions established with these three protein samples, at 1mL/min with a revolution speed of 1000rpm. There were high stationary phase retentions of around 60%, with effective separations, demonstrating the efficiency of the flat-twisted spiral tube assembly. The separation time of 6h was a limitation but can potentially be shortened by improving the strength of the column that will permit an increase in revolution speed and flow rate. This novel spiral separation column will allow rapid and efficient separation of mixtures with high yield of the constituent components. Published by Elsevier B.V.

Optimising mobile phase composition, its flow-rate and column temperature in HPLC using taboo search.

PubMed

Guillaume, Y C; Peyrin, E

2000-03-06

A chemometric methodology is proposed to study the separation of seven p-hydroxybenzoic esters in reversed phase liquid chromatography (RPLC). Fifteen experiments were found to be necessary to find a mathematical model which linked a novel chromatographic response function (CRF) with the column temperature, the water fraction in the mobile phase and its flow rate. The CRF optimum was determined using a new algorithm based on Glover's taboo search (TS). A flow-rate of 0.9 ml min(-1) with a water fraction of 0.64 in the ACN-water mixture and a column temperature of 10 degrees C gave the most efficient separation conditions. The usefulness of TS was compared with the pure random search (PRS) and simplex search (SS). As demonstrated by calculations, the algorithm avoids entrapment in local minima and continues the search to give a near-optimal final solution. Unlike other methods of global optimisation, this procedure is generally applicable, easy to implement, derivative free, conceptually simple and could be used in the future for much more complex optimisation problems.

Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

PubMed

Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

2015-07-01

Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Iptycene-based stationary phase with three-dimensional aromatic structure for highly selective separation of H-bonding analytes and aromatic isomers.

PubMed

Yang, Xiaohong; Han, Ying; Qi, Meiling; Chen, Chuanfeng

2016-05-06

Unique structures and molecular recognition ability endow iptycene derivatives with great potential as stationary phases in chromatography, which, however, has not been explored yet. Herein, we report the first example of utilizing a pentiptycene quinone (PQ) for gas chromatographic (GC) separations. Remarkably, the statically coated capillary column with the stationary phase achieved extremely high column efficiency of 4800 plates/m. It exhibited preferential retention and high resolving capability for H-bonding and aromatic analytes and positional isomers, showing advantages over the ordinary polysiloxane phase. Moreover, the fabricated iptycene column showed excellent separation repeatability with RSD values of 0.02-0.06% for intra-day, 0.20-0.35% for inter-day and 3.1-5.5% for between-column, respectively. In conclusion, iptycene derivatives as a new class of stationary phases show promising future for their use in GC separations. Copyright © 2016 Elsevier B.V. All rights reserved.

High-throughput determination of faropenem in human plasma and urine by on-line solid-phase extraction coupled to high-performance liquid chromatography with UV detection and its application to the pharmacokinetic study.

PubMed

Xie, Rui; Wen, Jun; Wei, Hua; Fan, Guorong; Zhang, Dabing

2010-05-01

An automated system using on-line solid-phase extraction and HPLC with UV detection was developed for the determination of faropenem in human plasma and urine. Analytical process was performed isocratically with two reversed-phase columns connected by a switching valve. After simple pretreatment for plasma and urine with acetonitrile, a volume of 100microl upper layer of the plasma or urine samples was injected for on-line SPE column switching HPLC-UV analysis. The analytes were retained on the self-made trap column (Lichrospher C(18), 4.6mmx37mm, 25microm) with the loading solvent (20mM NaH(2)PO(4) adjusted pH 3.5) at flow rate of 2mlmin(-1), and most matrix materials were removed from the column to waste. After 0.5min washing, the valve was switched to another position so that the target analytes could be eluted from trap column to analytical column in the back-flush mode by the mobile phase (acetonitrile-20mM NaH(2)PO(4) adjusted pH 3.5, 16:84, v/v) at flow rate of 1.5mlmin(-1), and then separated on the analytical column (Ultimate XB-C(18), 4.6mmx50mm, 5microm).The complete cycle of the on-line SPE preconcentration purification and HPLC separation of the analytes was 5min. Calibration curves with good linearities (r=0.9994 for plasma sample and r=0.9988 for urine sample) were obtained in the range 0.02-5microgml(-1) in plasma and 0.05-10microg ml(-1) in urine for faropenem. The optimized method showed good performance in terms of specificity, linearity, detection and quantification limits, precision and accuracy. The method was successfully utilized to quantify faropenem in human plasma and urine to support the clinical pharmacokinetic studies. Copyright 2009 Elsevier B.V. All rights reserved.

Experiment and modeling for the separation of guaifenesin enantiomers using simulated moving bed and Varicol units.

PubMed

Gong, Rujin; Lin, Xiaojian; Li, Ping; Yu, Jianguo; Rodrigues, Alirio E

2014-10-10

The separation of guaifenesin enantiomers by both simulated moving bed (SMB) process and Varicol process was investigated experimentally and theoretically, where the columns were packed with cellulose tris 3,5-dimethylphenylcarbamate (Chiralcel OD) stationary phase and a mixture of n-hexane and ethanol was used as mobile phase. The operation conditions were designed based on the separation region with the consideration of mass transfer resistance and axial dispersion, and the experiments to separate guaifenesin enantiomers were carried out on VARICOL-Micro unit using SMB process with the column configuration of 1/2/2/1 and Varicol process with the column configuration of 1/1.5/1.5/1, respectively. Single enantiomer with more than 99.0% purity was obtained in both processes with the productivity of 0.42 genantiomer/dcm(3) CSP for SMB process and 054 genantiomer/dcm(3) CSP for Varicol process. These experimental results obtained from SMB and Varicol processes were compared with those reported from literatures. In addition, according to the numerical simulation, the effects of solid-film mass transfer resistance and axial dispersion on the internal profiles were discussed, and the effect of column configuration on the separation performance of SMB and Varicol processes was analyzed for a few columns system. The feasibility and efficiency for the separation of guaifenesin enantiomers by SMB and Varicol processes were evaluated. Copyright © 2014 Elsevier B.V. All rights reserved.

Schinus terebinthifolius countercurrent chromatography (Part III): Method transfer from small countercurrent chromatography column to preparative centrifugal partition chromatography ones as a part of method development.

PubMed

das Neves Costa, Fernanda; Hubert, Jane; Borie, Nicolas; Kotland, Alexis; Hewitson, Peter; Ignatova, Svetlana; Renault, Jean-Hugues

2017-03-03

Countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC) are support free liquid-liquid chromatography techniques sharing the same basic principles and features. Method transfer has previously been demonstrated for both techniques but never from one to another. This study aimed to show such a feasibility using fractionation of Schinus terebinthifolius berries dichloromethane extract as a case study. Heptane - ethyl acetate - methanol -water (6:1:6:1, v/v/v/v) was used as solvent system with masticadienonic and 3β-masticadienolic acids as target compounds. The optimized separation methodology previously described in Part I and II, was scaled up from an analytical hydrodynamic CCC column (17.4mL) to preparative hydrostatic CPC instruments (250mL and 303mL) as a part of method development. Flow-rate and sample loading were further optimized on CPC. Mobile phase linear velocity is suggested as a transfer invariant parameter if the CPC column contains sufficient number of partition cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Dopamine-imprinted monolithic column for capillary electrochromatography.

PubMed

Aşır, Süleyman; Sarı, Duygu; Derazshamshir, Ali; Yılmaz, Fatma; Şarkaya, Koray; Denizli, Adil

2017-11-01

A dopamine-imprinted monolithic column was prepared and used in capillary electrochromatography as stationary phase for the first time. Dopamine was selectively separated from aqueous solution containing the competitor molecule norepinephrine, which is similar in size and shape to the template molecule. Morphology of the dopamine-imprinted column was observed by scanning electron microscopy. The influence of the organic solvent content of mobile phase, applied pressure and pH of the mobile phase on the recognition of dopamine by the imprinted monolithic column has been evaluated, and the imprinting effect in the dopamine-imprinted monolithic polymer was verified. Developed dopamine-imprinted monolithic column resulted in excellent separation of dopamine from structurally related competitor molecule, norepinephrine. Separation was achieved in a short period of 10 min, with the electrophoretic mobility of 5.81 × 10 -5  m 2 V -1 s -1 at pH 5.0 and 500 mbar pressure. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enantiomeric separation by capillary electrochromatography on a sulfated poly β-cyclodextrin modified silica-based monolith.

PubMed

Yuan, Ruijuan; Wang, Yan; Ding, Guosheng

2010-01-01

A sulfated poly β-cyclodextrin (SPCD) modified silica-based monolithic column was prepared for enantiomeric separation. First, 2-hydroxy-3-allyloxy-propyl-β-cyclodextrin (allyl-β-CD) was bonded onto a bifunctional reagent 3-(methacryloxy)propyltriethoxysilane (γ-MAPS) modified silica-based monolith through radical polymerization; the column was then sulfated with chlorosulfonic acid. The SPCD chiral stationary phase resolved the boring problem associated with desalting when sulfated CDs were synthesized to act as chiral additives. The inorganic salt in the column introduced during the sulfating process could be easily removed by washing the column with water for some time. Chiral compounds investigated were successfully resolved into their enantiomers on the SPCD modified monolith in the capillary electrochromatography (CEC) mode. Due to the existence of the -SO(3)H group, electrosmotic flow (EOF) was obviously increased, and all of the separations could be carried out in 20 min with only a minor loss in the column efficiency and resolution.

Shell and small particles; evaluation of new column technology.

PubMed

Fekete, Szabolcs; Fekete, Jeno; Ganzler, Katalin

2009-01-15

The performance of 5 cm long columns packed with shell particles was compared to totally porous sub-2 microm particles in gradient and isocratic elution separations of hormones (dienogest, finasteride, gestodene, levonorgestrel, estradiol, ethinylestradiol, noretistherone acetate, bicalutamide and tibolone). Peak capacities around 140-150 could be achieved in 25 min with the 5 cm long columns. The Ascentis Express column (packed with 2.7 microm shell particles) showed similar efficiency to sub-2 microm particles under gradient conditions. Applying isocratic separation, the column of 2.7 microm shell particles had a reduced plate height minimum of approximately h=1.6. It was much smaller than obtained with totally porous particles (h approximately = 2.8). The impedance time also proved more favorable with 2.7 microm shell particles than with totally porous particles. The influence of extra-column volume on column efficiency was investigated. The extra-column dispersion of the chromatographic system may cause a shift of the HETP curves.

Preparation of chitosan-graft-(β-cyclodextrin) based sol-gel stationary phase for open-tubular capillary electrochromatography.

PubMed

Lü, Haixia; Li, Qingyin; Yu, Xiaowei; Yi, Jiaojiao; Xie, Zenghong

2013-07-01

A novel open-tubular CEC column coated with chitosan-graft-(β-CD) (CDCS) was prepared using sol-gel technique. In the sol-gel approach, owing to the 3D network of sol-gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. The column efficiencies of 55,000∼163,000 plates/m for the isomeric xanthopterin and phenoxy acid herbicides using the sol-gel-derived CDCS columns were achieved. Good stabilities were demonstrated that the RSD values for the retention time of thiourea and isoxanthopterin were 1.3 and 1.4% (run to run, n = 5), 1.6 and 2.0% (day to day, n = 3), 2.9 and 3.1% (column to column, n = 3), respectively. The sol-gel-coated CDCS columns have shown improved separations of isomeric xanthopterin in comparison with CDCS-bonded capillary column. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A fully automated and fast method using direct sample injection combined with fused-core column on-line SPE-HPLC for determination of ochratoxin A and citrinin in lager beers.

PubMed

Lhotská, Ivona; Šatínský, Dalibor; Havlíková, Lucie; Solich, Petr

2016-05-01

A new fast and sensitive method based on on-line solid-phase extraction on a fused-core precolumn coupled to liquid chromatography with fluorescence detection has been developed for ochratoxin A (OTA) and citrinin (CIT) determination in lager beer samples. Direct injection of 100 μL filtered beer samples into an on-line SPE-HPLC system enabled fast and effective sample extraction including separation in less than 6 min. Preconcentration of OTA and CIT from beer samples was performed on an Ascentis Express RP C18 guard column (5 × 4.6 mm), particle size 2.7 μm, with a mobile phase of methanol/0.5% aqueous acetic acid pH 2.8 (30:70, v/v) at a flow rate of 2.0 mL min(-1). The flow switch from extraction column to analytical column in back-flush mode was set at 2.0 min and the separation was performed on the fused-core column Ascentis Express Phenyl-Hexyl (100 × 4.6 mm), particle size 2.7 μm, with a mobile phase acetonitrile/0.5% aqueous acetic acid pH 2.8 in a gradient elution at a flow rate of 1.0 mL min(-1) and temperature of 50 °C. Fluorescence excitation/emission detection wavelengths were set at 335/497 nm. The accuracy of the method, defined as the mean recoveries of OTA and CIT from light and dark beer samples, was in the range 98.3-102.1%. The method showed high sensitivity owing to on-line preconcentration; LOQ values were found to be 10 and 20 ng L(-1) for OTA and CIT, respectively. The found values of OTA and CIT in all tested light, dark and wheat beer samples were significantly below the maximum tolerable limits (3.0 μg kg(-1) for OTA and 2000 μg kg(-1) for CIT) set by the European Union.

Separation of fatty acid methyl esters by GC-online hydrogenation × GC.

PubMed

Delmonte, Pierluigi; Fardin-Kia, Ali Reza; Rader, Jeanne I

2013-02-05

The separation of fatty acid methyl esters (FAME) provided by a 200 m × 0.25 mm SLB-IL111 capillary column is enhanced by adding a second dimension of separation ((2)D) in a GC × GC design. Rather than employing two GC columns of different polarities or using different elution temperatures, the separation in the two-dimensional space is achieved by altering the chemical structure of selected analytes between the two dimensions of separation. A capillary tube coated with palladium is added between the first dimension of separation ((1)D) column and the cryogenic modulator, providing the reduction of unsaturated FAMEs to their fully saturated forms. The (2)D separation is achieved using a 2.5 m × 0.10 mm SLB-IL111 capillary column and separates FAMEs based solely on their carbon skeleton. The two-dimensional separation can be easily interpreted based on the principle that all the saturated FAMEs lie on a straight diagonal line bisecting the separation plane, while the FAMEs with the same carbon skeleton but differing in the number, geometric configuration or position of double bonds lie on lines parallel to the (1)D time axis. This technique allows the separation of trans fatty acids (FAs) and polyunsaturated FAs (PUFAs) in a single experiment and eliminates the overlap between PUFAs with different chain lengths. To our knowledge, this the first example of GC × GC in which a chemical change is instituted between the two dimensions to alter the relative retentions of components and identify unsaturated FAMEs.

Silica particles encapsulated poly(styrene-divinylbenzene) monolithic stationary phases for micro-high performance liquid chromatography.

PubMed

Bakry, R; Stöggl, W M; Hochleitner, E O; Stecher, G; Huck, C W; Bonn, G K

2006-11-03

In the paper we demonstrate a new approach for the preparation and application of continuous silica bed columns that involve encapsulation (entrapment) of functionalized silica microparticles, which can be used as packing material in micro high performance liquid chromatography (micro-HPLC) and capillary electrochromatography (CEC). Like traditional packed columns, these capillaries possess characterized silica particles that offer high phase ratio and narrow pore size distribution leading to high retention and separation efficiency, respectively. More importantly, immobilization of the microparticles stabilizes the separation bed and eliminates the need for retaining frits. The developed capillary columns were fabricated in exactly the same way as a packed capillary column (slurry packing) but with an additional entrapment step. This immobilization of the packed bed was achieved by in situ polymerization of styrene and divinylbenzene in presence of decanol as a porogen and azobisisobutyronitrile as thermal initiator. Silica particles with different particle sizes and pore sizes ranging from 60 to 4000 A were studied. In addition different modified silica was used, including C-18 reversed phase, anion exchange and chiral stationary phases. Efficient separation of polyphenolic compounds, peptides, proteins and even DNA mutation were achieved using the developed technique depending on the properties of the silica particles used (particles pore size). For example, using 3 microm ProntoSIL C-18 particles with 300 A pore size, separation efficiencies in the range of 120,000-200,000 plates/m were obtained for protein separation, in a 6 cm x 200 microm i.d. capillary column. Using encapsulated silica C-18 with 1000 A pore size, separation of DNA homo and hetero duplexes were achieved under denaturing HPLC conditions for mutation detection. In addition, nucleotides were separated using anion exchange material encapsulated with poly(styrene-divinylbenzene) (PS/DVB), which indicated that the chromatographic properties of the silica packing material were still active after polymerization. The prepared capillary columns were found to be stable and could easily be operated continuously up to a pressure of 350 bar without column damage and capillary can be cut to any desired length.

Determination of noscapine, hexylresorcinol and anethole in cough lozenges by liquid chromatography.

PubMed

Lucangioli, S; Fernández Otero, G; Rodríguez, V; Carducci, C N

1996-06-01

A liquid chromatographic method was developed for the simultaneous separation and determination of noscapine hydrochloride, hexylresorcinol and anethole in cough lozenges. Analysis was performed on a phenyl column with phosphate buffer- acetonitrile as mobile phase and the separated components were detected at 282 mm. Recoveries obtained for the analytes were of 94.6% for noscapine hydrochloride, 99.1% for hexylresorcinol and 96.3% for anethole. The values of the relative standard deviation were 0.8% for noscapine hydrochloride, 1.5% for hexylresorcinol and 1.1% for anethole. The analytical method was validated and a system suitability test was accomplished for the chromatographic method.

Hydrophilic interaction liquid chromatography in the speciation analysis of selenium.

PubMed

Sentkowska, Aleksandra; Pyrzynska, Krystyna

2018-02-01

The hydrophilic interaction liquid chromatography (HILIC) coupled to mass spectrometry was employed to study retention behavior of selected selenium compounds using two different HILIC stationary phases: silica and zwitterionic. Two organic solvents - acetonitrile and methanol - were compared as a component of mobile phase. Separation parameters such as a content of organic modifier, the eluent pH and inorganic buffer concentration were investigated. Based on all observations, methanol seems to be beneficial for the separation of studied compounds. The optimal HILIC separation method involved silica column and eluent composed of 85% MeOH and CH 3 COONH 4 (8 mM, pH 7) was compared to RP method in terms of time of the single run, the separation efficiency and limit of detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Two-dimensional ion chromatography for the separation of ionic organophosphates generated in thermally decomposed lithium hexafluorophosphate-based lithium ion battery electrolytes.

PubMed

Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Menzel, Jennifer; Wiemers-Meyer, Simon; Winter, Martin; Nowak, Sascha

2015-08-28

A two-dimensional ion chromatography (IC/IC) technique with heart-cutting mode for the separation of ionic organophosphates was developed. These analytes are generated during thermal degradation of three different commercially available Selectilyte™ lithium ion battery electrolytes. The composition of the investigated electrolytes is based on 1M lithium hexafluorophosphate (LiPF6) dissolved in ethylene carbonate/dimethyl carbonate (50:50wt%, LP30), ethylene carbonate/diethyl carbonate (50:50wt%, LP40) and ethylene carbonate/ethyl methyl carbonate (50:50wt%, LP50). The organophosphates were pre-separated from PF6(-) anion on the low capacity A Supp 4 column, which was eluted with a gradient step containing acetonitrile. The fraction containing analytes was retarded on a pre-concentration column and after that transferred to the high capacity columns, where the separation was performed isocratically. Different stationary phases and eluents were applied on the 2nd dimension for the investigation of retention times, whereas the highly promising results were obtained with a high capacitive A Supp 10 column. The organophosphates generated in LP30 and LP40 electrolytes could be separated by application of an aqueous NaOH eluent providing fast analysis time within 35min. For the separation of the organophosphates of LP50 electrolyte due to its complexity a NaOH eluent containing a mixture of methanol/H2O was necessary. In addition, the developed two dimensional IC method was hyphenated to an inductively coupled plasma mass spectrometer (ICP-MS) using aqueous NaOH without organic modifiers. This proof of principle measurement was carried out for future quantitative investigation regarding the concentration of the ionic organophosphates. Furthermore, the chemical stability of several ionic organophosphates in water and acetonitrile at room temperature over a period of 10h was investigated. In both solvents no decomposition of the investigated analytes was observed and therefore water as solvent for dilution of samples was proved as suitable. Copyright © 2015 Elsevier B.V. All rights reserved.

Ion chromatographic methods for the detection of starch hydrolysis products in ruminal digesta.

PubMed

Barsuhn, K; Kotarski, S F

1991-06-21

Dionex high-performance ion chromatographic methods were evaluated for separation and quantitation of plant sugars and starch digestion products in the ruminal digesta of cattle. Mono- and disaccharides were eluted from a Dionex CarboPac PA1 column with sodium hydroxide used isocratically or as a pH gradient. Maltooligosaccharides which had a degree of polymerization (DP) less than 30 glucose residues were eluted in 60 min by a sodium hydroxide eluent containing a sodium acetate gradient. Carbohydrates were detected amperometrically. Responses were linear (r2 greater than 0.99) for glucose, disaccharides and maltooligosaccharides (DP less than 8). Precipitation and solid-phase extraction methods were evaluated for clean-up of samples of feedstuffs, ruminal contents, and bacterial culture fluids. Perchloric acid precipitation hydrolyzed sucrose but did not affect recoveries of cellobiose, isomaltose or maltose. Ethanol in concentrations of 79 and 86% precipitated maltooligosaccharides having chain lengths larger than 14 and 9 glucose residues, respectively. Maltooligosaccharide recoveries from solid-phase extraction columns varied with maltooligosaccharide size and column packing. Recoveries were greater than 94% for short chains (DP less than 6) eluted from phenyl-substituted columns and variable for all oligosaccharides eluted from C18 columns. Applications of these methods are presented and include: (1) detection of sugars in ruminant feed, (2) monitoring changes in ruminal sugars after feeding and (3) monitoring changes in extracellular sugars and oligosaccharides in the culture fluids of the ruminal bacterium, Bacteroides ruminicola.

Determination of active components of Ginkgo biloba in human urine by capillary high-performance liquid chromatography/mass spectrometry with on-line column-switching purification.

PubMed

Ding, Shujing; Dudley, Ed; Chen, Lijuan; Plummer, Sue; Tang, Jiandong; Newton, Russell P; Brenton, A Gareth

2006-01-01

Ginkgo biloba is one of the most popular herbal nutritional supplements, with terpene lactones and flavonoids being the two major active components. An on-line purification high-performance liquid chromatography/mass spectrometry (HPLC/MS) method was successfully developed for the quantitative determination of flavonoids and terpene lactones excreted in human urine after ingesting the herbal supplement. Satisfactory separation was obtained using a C18 capillary column made in-house with sample clean-up and pre-concentration achieved using a C18 pre-column with column switching. High selectivity and limits of detection of 1-18 ng/mL were achieved using a selected ion monitoring (SIM) scan in negative ion mode; the on-line solid-phase extraction (SPE) recovery of the active components in Ginkgo biloba determined in this study was greater than 75%. Copyright 2006 John Wiley & Sons, Ltd.

Simulation of a Novel Single-column Cryogenic Air Separation Process Using LNG Cold Energy

NASA Astrophysics Data System (ADS)

Jieyu, Zheng; Yanzhong, Li; Guangpeng, Li; Biao, Si

In this paper, a novel single-column air separation process is proposed with the implementation of heat pump technique and introduction of LNG coldenergy. The proposed process is verifiedand optimized through simulation on the Aspen Hysys® platform. Simulation results reveal that thepower consumption per unit mass of liquid productis around 0.218 kWh/kg, and the total exergy efficiency of the systemis 0.575. According to the latest literatures, an energy saving of 39.1% is achieved compared with those using conventional double-column air separation units.The introduction of LNG cold energy is an effective way to increase the system efficiency.

On-line comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for preparative isolation of Peucedanum praeruptorum.

PubMed

Wang, Xin-Yuan; Li, Jia-Fu; Jian, Ya-Mei; Wu, Zhen; Fang, Mei-Juan; Qiu, Ying-Kun

2015-03-27

A new on-line comprehensive preparative two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was developed for the separation of complicated natural products. It was based on the use of a silica gel packed medium-pressure column as the first dimension and an ODS preparative HPLC column as the second dimension. The two dimensions were connected with normal-phase (NP) and reversed-phase (RP) enrichment units, involving a newly developed airflow assisted adsorption (AAA) technique. The instrument operation and the performance of this NPLC × RPLC separation method were illustrated by gram-scale isolation of ethanol extract from the roots of Peucedanum praeruptorum. In total, 19 compounds with high purity were obtained via automated multi-step preparative separation in a short period of time using this system, and their structures were comprehensively characterized by ESI-MS, (1)H NMR, and (13)C NMR. Including two new compounds, five isomers in two groups with identical HPLC and TLC retention values were also obtained and identified by 1D NMR and 2D NMR. This is the first report of an NPLC × RPLC system successfully applied in an on-line preparative process. This system not only solved the interfacing problem of mobile-phase immiscibility caused by NP and RP separation, it also exhibited apparent advantages in separation efficiency and sample treatment capacity compared with conventional methods. Copyright © 2015 Elsevier B.V. All rights reserved.

Instrument for the measurement and determination of chemical pulse column parameters

DOEpatents

Marchant, Norman J.; Morgan, John P.

1990-01-01

An instrument for monitoring and measuring pneumatic driving force pulse parameters applied to chemical separation pulse columns obtains real time pulse frequency and root mean square amplitude values, calculates column inch values and compares these values against preset limits to alert column operators to the variations of pulse column operational parameters beyond desired limits.

10 CFR Appendix E to Part 110 - Illustrative List of Chemical Exchange or Ion Exchange Enrichment Plant Equipment and Components...

Code of Federal Regulations, 2011 CFR

2011-01-01

... contactors employed in the separation cascade can be liquid-liquid exchange columns (such as pulsed columns.... Plastic, plastic-lined (including use of fluorocarbon polymers) and/or glass-lined columns and piping are therefore used. (1) Liquid-liquid exchange columns. Countercurrent liquid-liquid exchange columns having...

10 CFR Appendix E to Part 110 - Illustrative List of Chemical Exchange or Ion Exchange Enrichment Plant Equipment and Components...

Code of Federal Regulations, 2013 CFR

2013-01-01

... contactors employed in the separation cascade can be liquid-liquid exchange columns (such as pulsed columns.... Plastic, plastic-lined (including use of fluorocarbon polymers) and/or glass-lined columns and piping are therefore used. (1) Liquid-liquid exchange columns. Countercurrent liquid-liquid exchange columns having...

10 CFR Appendix E to Part 110 - Illustrative List of Chemical Exchange or Ion Exchange Enrichment Plant Equipment and Components...

Code of Federal Regulations, 2014 CFR

2014-01-01

... contactors employed in the separation cascade can be liquid-liquid exchange columns (such as pulsed columns.... Plastic, plastic-lined (including use of fluorocarbon polymers) and/or glass-lined columns and piping are therefore used. (1) Liquid-liquid exchange columns. Countercurrent liquid-liquid exchange columns having...

Superficially porous particles columns for super fast HPLC separations.

PubMed

Ali, Imran; Al-Othman, Zeid A; Al-Za'abi, Mohammed

2012-08-01

Superficially porous silica particles columns (SPSPCs) are manufactured by different companies. The most common have the brand names Halo, Ascentis Express and Kinetex. These columns provide super fast, sharp peaks and moderate sample loading and back pressure. These are available in different chemistries such as C₈, C₁₈, RP Amide and Hilic. Normally, the silica gel particles have 2.7 and 1.7 µm total and inner solid core diameters with 0.5 µm thick outer porous layer, 90 Å pore size and 150 m²/g surface area. They have been used for the separation and identification of low and high molecular weight compounds. The present article describes the state of the art of superficially porous silica particles based columns with special emphasis on their structures, mechanisms of separation, applications and comparison. Copyright © 2012 John Wiley & Sons, Ltd.

Influence of the Kinetics of Heat and Mass Transfer in a Binary-Rectification Column on the Realizability Range of its Regimes

NASA Astrophysics Data System (ADS)

Zaeva, M. A.; Tsirlin, A. M.; Sukin, I. A.

2018-05-01

The range of realizable rates of flows in a binary-rectification column in which heat is supplied into the boiler and is removed from the dephlegmator was investigated. It is shown that this range is determined by two characteristic parameters related to the kinetics of heat and mass transfer in the column and the composition of the mixture subjected to separation. The limiting capabilities of a cascade of two binary-rectification columns for the separation of a ternary mixture in it were considered. The conditions for an optimum sequence of separation of a mixture in this cascade and for a consistent arrangement of its heat and mass exchange surfaces and the relation between the ultimate production rate of the cascade and the total heat losses in it were determined.

Influence of the Kinetics of Heat and Mass Transfer in a Binary-Rectification Column on the Realizability Range of its Regimes

NASA Astrophysics Data System (ADS)

Zaeva, M. A.; Tsirlin, A. M.; Sukin, I. A.

2018-03-01

The range of realizable rates of flows in a binary-rectification column in which heat is supplied into the boiler and is removed from the dephlegmator was investigated. It is shown that this range is determined by two characteristic parameters related to the kinetics of heat and mass transfer in the column and the composition of the mixture subjected to separation. The limiting capabilities of a cascade of two binary-rectification columns for the separation of a ternary mixture in it were considered. The conditions for an optimum sequence of separation of a mixture in this cascade and for a consistent arrangement of its heat and mass exchange surfaces and the relation between the ultimate production rate of the cascade and the total heat losses in it were determined.

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

PubMed

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

1995-12-01

Strontium-90 may be determined by beta-counting its yttrium-90 daughter following separation by ion-chromatography, using a three column system comprising a chelating concentrator column, a cation-exchange column and an anion-exchange separator column. The column system has previously been applied to the determination of strontium-90 in water and urine samples. The applicability of the system to the analysis of milk is hampered by the large concentrations of calcium present, which significantly reduces the extraction of yttrium-90 by the concentrator column. A maximum of approximately 200 mg of calcium can be present for the successful extraction of yttrium-90, which greatly limits the quantity of milk that can be analysed. The quantity of milk analysed can be increased by the inclusion of a controlled precipitation step prior to the ion-chromatographic separation. The precipitation is carried out on acid digested milk samples by the addition of ammonia solution until the addition of one drop causes a reduction in pH resulting in the precipitation of calcium hydrogenphosphate. Under these conditions, approximately 20% of the calcium present in the original milk sample is precipitated, yttrium-90 is precipitated whereas strontium-90 is not precipitated. Dissolution of the precipitate, followed by separation of yttrium-90 using the ion-chromatography system facilitates the analysis of a litre of milk with recoveries of greater than 80%.

A validated UHPLC method for the determination of caffeoylquinic and di-caffeoylquinic acids in green coffee extracts using an RP-Amide fused-core column.

PubMed

Fibigr, Jakub; Majorová, Michaela; Kočová Vlčková, Hana; Solich, Petr; Šatínský, Dalibor

2018-03-20

The presented work describes the development and validation of a rapid UHPLC-UV method using a fused core particle column with an RP-Amide stationary phase for the separation and quantitative analysis of caffeoylquinic and di-caffeoylquinic acids in green coffee extracts. Three caffeoylquinic acids (3-caffeoylquinic acid, 4-caffeoylquinic acid, and 5-caffeoylquinic acid) and two di-caffeoylquinic acids (1,3-di-caffeoylquinic acid, and 3,5-di-caffeoylquinic acid) were separated and analyzed in 8 min. That was possible due to the unique selectivity of the RP-Amide stationary phase for the analyzed acids. The retention behavior of all analytes under different compositions of the mobile phase on different columns was evaluated in this study. The optimal chromatographic separation was performed using an Ascentis Express RP-Amide (100 × 2.1 mm) fused-core column with a particle size of 2.7 μm at a temperature of 30 °C. For validation of the newly developed method, acetonitrile was used as mobile phase B and 5% formic acid, filtrated through a 0.22 μm filter, was used as mobile phase A. They were delivered at a flow rate of 0.9 mL min -1 according to the elution gradient program. The detection wavelength was set at 325 nm. A solid-liquid extraction with a solution of methanol and a 5% water solution of formic acid (25 + 75 v/v) using an ultrasonic bath was chosen for the preparation of the available commercial samples of food supplements containing a green coffee extract. Recoveries for all analyzed acids were 98.2-101.0% and the relative standard deviation ranged from 0.3% to 1.4% for intra-day and from 0.3% to 3.0% for inter-day repeatability. The limits of detection were in the range of 0.30-0.53 μg mL -1 . Copyright © 2018. Published by Elsevier B.V.

Enantioseparation of racemic aminoglutethimide using asynchronous simulated moving bed chromatography.

PubMed

Lin, Xiaojian; Gong, Rujin; Li, Jiaxu; Li, Ping; Yu, Jianguo; Rodrigues, Alirio E

2016-10-07

The separation of aminoglutethimide enantiomers by the continuous multicolumn chromatographic processes were investigated experimentally and theoretically, where the columns were packed with cellulose tris 3,5-dimethylphenyl-carbamate stationary phase (brand name Chiralcel OD) and mobile phase was a mixture of n-hexane and ethanol with monoethanolamine additive. The continuous enantioseparation processes included a synchronous shifting process (SMB) and an asynchronous shifting process (VARICOL), which allowed reducing the column number (here from six-column SMB to five-column VARICOL process). Transport-dispersive model with the consideration of both intraparticle mass transfer resistance and axial dispersion was adopted to design and optimize the operation conditions for the separation of aminoglutethimide enantiomers by SMB process and VARICOL process. According to the optimized operation conditions, experiments were carried out on VARICOL-Micro unit using five-column VARICOL process with 1/1.5/1.5/1 configuration and six-column SMB process with 1/2/2/1 configuration. Products of R-aminoglutethimide (R-AG) enantiomer and S-aminoglutethimide (S-AG) enantiomer with more than 99.0% purity were obtained continuously from extract stream and raffinate stream, respectively. Furthermore, the experiemntal data obtained from five-column VARICOL process were compared with that from six-column SMB process, the feasibility and efficiency for the separation of guaifenesin enantiomers by VARICOL processes were evaluated. Copyright © 2016 Elsevier B.V. All rights reserved.

Practical comparison of 2.7 microm fused-core silica particles and porous sub-2 microm particles for fast separations in pharmaceutical process development.

PubMed

Abrahim, Ahmed; Al-Sayah, Mohammad; Skrdla, Peter; Bereznitski, Yuri; Chen, Yadan; Wu, Naijun

2010-01-05

Fused-core silica stationary phases represent a key technological advancement in the arena of fast HPLC separations. These phases are made by fusing a 0.5 microm porous silica layer onto 1.7 microm nonporous silica cores. The reduced intra-particle flow path of the fused particles provides superior mass transfer kinetics and better performance at high mobile phase velocities, while the fused-core particles provide lower pressure than sub-2 microm particles. In this work, chromatographic performance of the fused-core particles (Ascentis Express) was investigated and compared to that of sub-2 microm porous particles (1.8 microm Zorbax Eclipse Plus C18 and 1.7 microm Acquity BEH C18). Specifically, retention, selectivity, and loading capacity were systematically compared for these two types of columns. Other chromatographic parameters such as efficiency and pressure drop were also studied. Although the fused-core column was found to provide better analyte shape selectivity, both columns had similar hydrophobic, hydrogen bonding, total ion-exchange, and acidic ion-exchange selectivities. As expected, the retention factors and sample loading capacity on the fused-core particle column were slightly lower than those for the sub-2 microm particle column. However, the most dramatic observation was that similar efficiency separations to the sub-2 microm particles could be achieved using the fused-core particles, without the expense of high column back pressure. The low pressure of the fused-core column allows fast separations to be performed routinely on a conventional LC system without significant loss in efficiency or resolution. Applications to the HPLC impurity profiling of drug substance candidates were performed using both types of columns to validate this last point.

Comparison of twin-cell centrifugal partition chromatographic columns with different cell volume.

PubMed

Goll, Johannes; Audo, Gregoire; Minceva, Mirjana

2015-08-07

Two twin-cell centrifugal partition chromatographic columns (SCPC 250 and SCPE-250-BIO, Armen Instrument, France) with the same column volume but different cell size and number were compared in terms of stationary phase retention and column efficiency. The columns were tested with two types of solvent systems: a commonly used organic solvent based biphasic system from the ARIZONA solvent system family and a polymer/salt based aqueous two phase system (ATPS). The efficiency of the columns was evaluated by pulse injection experiments of two benzenediols (pyrocatechol and hydroquinone) in the case of the ARIZONA system and a protein mixture (myoglobin and lysozyme) in the case of the ATPS. As result of high stationary phase retention, the column with the lower number of larger twin-cells (SCPE-250-BIO) is suitable for protein separations using ATPS. On the other hand, due to higher column efficiency, the column with the greater number of smaller cells (SCPC 250) is superior for batch elution separations performed with standard liquid-liquid chromatography organic solvent based biphasic systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Radionuclide Sensors and Systems for Monitoring Technetium-99 and Strontium-90 in Groundwater at the Hanford Site

NASA Astrophysics Data System (ADS)

Grate, J. W.; O'Hara, M. J.; Egorov, O. B.; Burge, S. R.

2009-12-01

We have developed automated sensor and analyzer devices for detection and monitoring of trace radionuclides in water, using preconcentrating columns and radiometric detection. The preconcentrating minicolumn sensor concept combines selective capture and detection in a single functional unit, where the column contains tens to hundreds of milligrams of selectively sorbent material, and the entire column content is monitored with a radiometric detector. Compared to thin film sensors with a few microgram of sorbent, this approach achieves tremendous preconcentration with efficient mass transport via pumping. Furthermore, in an equilibration-based mode of operation, the preconcentration by the sensor is maximized while eliminating the need for consumable reagents to regenerate the column; it can simply be re-equilibrated. We have demonstrated quantification of radionuclides such as technetium-99 to levels below drinking water standards in an equilibration-based process that produces steady state signals, signal proportional to concentration, and easy re-equilibration to new concentration levels. Alternatively, analyzers can be developed with separate separation and detection units that are fluidically linked. We have demonstrated detection of strontium-90 to levels below drinking water standards by this approach. We are developing autonomous systems for at-site monitoring on the Hanford Site in Washington State, using the fluidic sensor and analyzer methods, with the aim of monitoring natural and accelerated attenuation processes, remediation and barrier performance, and contaminant fluxes in the environment. Figure 1. The strontium-90 monitoring method deployed as part of the Burge Environmental Universal Sensor Platform, shown on the shores of the Columbia River on the Hanford site in Washington State.

A study of retention characteristics and quality control of nutraceuticals containing resveratrol and polydatin using fused-core column chromatography.

PubMed

Fibigr, Jakub; Šatínský, Dalibor; Solich, Petr

2016-02-20

A new high-performance liquid chromatography method using fused-core column for fast separation of resveratrol and polydatin has been developed and used for quality control of nutraceuticals with resveratrol and polydatin content. Retention characteristics (log k) were studied under different conditions on C-18, RP-Amide C-18, Phenyl-hexyl, Pentafluorophenyl (F5) and Cyano stationary phases for both compounds. The effect of the volume fraction of acetonitrile on a retention factors log k of resveratrol and polydatin were evaluated. The optimal separation conditions for resveratrol, polydatin and internal standard p-nitrophenol were found on the fused-core column Ascentis Express ES-Cyano (100×3.0mm), particle size 2.7μm, with mobile phase acetonitrile/water solution with 0.5% acetic acid pH 3 (20:80, v/v) at a flow rate of 1.0mL/min and at 60°C. The detection wavelength was set at 305nm. Under the optimal chromatographic conditions, good linearity with regression coefficients in the range (r=0.9992-0.9998; n=10) for both compounds was achieved. Commercial samples of nutraceuticals were extracted with methanol using ultrasound bath for 15min. A 5μL sample volume of the filtered solution was directly injected into the HPLC system. Accuracy of the method defined as a mean recovery was in the range 83.2-107.3% for both nutraceuticals. The intraday method precision was found satisfactory and relative standard deviations of sample analysis were in the range 0.8-4.7%. The developed method has shown high sample throughput during sample preparation process, modern separation approach, and short time (3min) of analysis. The results of study showed that the declared content of resveratrol and polydatin varied widely in different nutraceuticals according the producers (71.50-115.00% of declared content). Copyright © 2015 Elsevier B.V. All rights reserved.

Development, validation and evaluation of an analytical method for the determination of monomeric and oligomeric procyanidins in apple extracts.

PubMed

Hollands, Wendy J; Voorspoels, Stefan; Jacobs, Griet; Aaby, Kjersti; Meisland, Ane; Garcia-Villalba, Rocio; Tomas-Barberan, Francisco; Piskula, Mariusz K; Mawson, Deborah; Vovk, Irena; Needs, Paul W; Kroon, Paul A

2017-04-28

There is a lack of data for individual oligomeric procyanidins in apples and apple extracts. Our aim was to develop, validate and evaluate an analytical method for the separation, identification and quantification of monomeric and oligomeric flavanols in apple extracts. To achieve this, we prepared two types of flavanol extracts from freeze-dried apples; one was an epicatechin-rich extract containing ∼30% (w/w) monomeric (-)-epicatechin which also contained oligomeric procyanidins (Extract A), the second was an oligomeric procyanidin-rich extract depleted of epicatechin (Extract B). The parameters considered for method optimisation were HPLC columns and conditions, sample heating, mass of extract and dilution volumes. The performance characteristics considered for method validation included standard linearity, method sensitivity, precision and trueness. Eight laboratories participated in the method evaluation. Chromatographic separation of the analytes was best achieved utilizing a Hilic column with a binary mobile phase consisting of acidic acetonitrile and acidic aqueous methanol. The final method showed linearity for epicatechin in the range 5-100μg/mL with a correlation co-efficient >0.999. Intra-day and inter-day precision of the analytes ranged from 2 to 6% and 2 to 13% respectively. Up to dp3, trueness of the method was >95% but decreased with increasing dp. Within laboratory precision showed RSD values <5 and 10% for monomers and oligomers, respectively. Between laboratory precision was 4 and 15% (Extract A) and 7 and 30% (Extract B) for monomers and oligomers, respectively. An analytical method for the separation, identification and quantification of procyanidins in an apple extract was developed, validated and assessed. The results of the inter-laboratory evaluation indicate that the method is reliable and reproducible. Copyright © 2017. Published by Elsevier B.V.

Advances in organic polymer-based monolithic column technology for high-resolution liquid chromatography-mass spectrometry profiling of antibodies, intact proteins, oligonucleotides, and peptides.

PubMed

Eeltink, Sebastiaan; Wouters, Sam; Dores-Sousa, José Luís; Svec, Frantisek

2017-05-19

This review focuses on the preparation of organic polymer-based monolithic stationary phases and their application in the separation of biomolecules, including antibodies, intact proteins and protein isoforms, oligonucleotides, and protein digests. Column and material properties, and the optimization of the macropore structure towards kinetic performance are also discussed. State-of-the-art liquid chromatography-mass spectrometry biomolecule separations are reviewed and practical aspects such as ion-pairing agent selection and carryover are presented. Finally, advances in comprehensive two-dimensional LC separations using monolithic columns, in particular ion-exchange×reversed-phase and reversed-phase×reversed-phase LC separations conducted at high and low pH, are shown. Copyright © 2017 Elsevier B.V. All rights reserved.

Separation of polychlorinated biphenyls by fast gas chromatography.

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

Alvarado, J. S.; Silzer, J.; Lemley, F.

1997-12-01

The separation of commercially available polychlorinated biphenyls (PCBs) by fast gas chromatography (fast GC) has been studied. Aroclor 1254 was separated by using two column types: DB-1 and SPB-608. The fast GC used a split-splitless injector to introduce the sample, followed by a cold trap at -90 C to focus the sample. Rapid heating was used to introduce the sample into the short chromatographic column to decrease band broadening. Hydrogen was the carrier gas at velocities of 100 to 125 cm s-1. Analyses were performed by using an electron capture detector (ECD). Separation was achieved with both columns in lessmore » than 6 min. With the greatly shortened run times, reproducibility can be tested quickly and consequently with low cost.« less