A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Selected papers from the latest issue:
Hydrophilic interaction liquid chromatography of anthranilic acid-labelled oligosaccharides with a 4-aminobenzoic acid ethyl ester–labelled dextran hydrolysate internal standard
11 February 2012, 22:28:43
Publication year: 2012
Source: Journal of Chromatography A, Available online 11 February 2012
David C.A. Neville, Dominic Alonzi, Terry D. Butters
Hydrophilic interaction liquid chromatography (HILIC) of fluorescently-labelled oligosaccharides is used in many laboratories to analyze complex oligosaccharide mixtures. Separations are routinely performed using a TSK gel-Amide 80 HPLC column, and retention times of different oligosaccharide species are converted to glucose unit (GU) values that are determined with reference to an external standard. However, if retention times were to be compared with an internal standard, consistent and more accurate GU values would be obtained. We present a method to perform internal standard-calibrated HILIC of fluorescently-labelled oligosaccharides. The method relies on co-injection of 4-aminobenzoic acid ethyl ester (4-ABEE)-labelled internal standard and detection by UV absorption, with 2-AA (2-aminobenzoic acid)-labelled oligosaccharides. 4-ABEE is a UV chromophore and a fluorophore, but there is no overlap of the fluorescent spectrum of 4-ABEE with the commonly used fluorescent reagents. The dual nature of 4-ABEE allows for accurate calculation of the delay between UV and fluorescent signals when determining the GU values of individual oligosaccharides. The GU values obtained are inherently more accurate as slight differences in gradients that can influence retention are negated by use of an internal standard. Therefore, this paper provides the first method for determination of HPLC-derived GU values of fluorescently-labelled oligosaccharides using an internal calibrant.
Source: Journal of Chromatography A, Available online 11 February 2012
David C.A. Neville, Dominic Alonzi, Terry D. Butters
Hydrophilic interaction liquid chromatography (HILIC) of fluorescently-labelled oligosaccharides is used in many laboratories to analyze complex oligosaccharide mixtures. Separations are routinely performed using a TSK gel-Amide 80 HPLC column, and retention times of different oligosaccharide species are converted to glucose unit (GU) values that are determined with reference to an external standard. However, if retention times were to be compared with an internal standard, consistent and more accurate GU values would be obtained. We present a method to perform internal standard-calibrated HILIC of fluorescently-labelled oligosaccharides. The method relies on co-injection of 4-aminobenzoic acid ethyl ester (4-ABEE)-labelled internal standard and detection by UV absorption, with 2-AA (2-aminobenzoic acid)-labelled oligosaccharides. 4-ABEE is a UV chromophore and a fluorophore, but there is no overlap of the fluorescent spectrum of 4-ABEE with the commonly used fluorescent reagents. The dual nature of 4-ABEE allows for accurate calculation of the delay between UV and fluorescent signals when determining the GU values of individual oligosaccharides. The GU values obtained are inherently more accurate as slight differences in gradients that can influence retention are negated by use of an internal standard. Therefore, this paper provides the first method for determination of HPLC-derived GU values of fluorescently-labelled oligosaccharides using an internal calibrant.
Highlights
► Method development for analysing oligosaccharides ► Internal calibration ► UV-labelled dextran standardDetermination of pharmaceutically related compounds by suppressed ion chromatography: III. Role of electrolytic suppressor design
11 February 2012, 22:28:43
Publication year: 2012
Source: Journal of Chromatography A, Available online 11 February 2012
Naama Karu, Greg W. Dicinoski, Melissa Hanna-Brown, Kannan Srinivasan, Christopher A. Pohl, ...
For the hyphenation of ion chromatography to nebulising detectors or mass spectrometry, suppression of the non-volatile ionic eluent to water is a required step to avoid elevated detector baselines. Presented here is a study of three new designs of electrolytic suppressors, incorporating high ion-exchange capacity screens and high ion-exchange capacity membranes in different thickness and composition. These designs aim to minimise hydrophobic interactions of the suppressor with organic analytes and to provide higher compatibility with eluents containing acetonitrile. In comparison with a commercially-available electrolytic suppressor and also a commercially available chemical suppressor, the new high-capacity suppressor showed superior performance, exhibiting minimal interactions with a test set of analytes under the examined conditions. This led to the attainment of high recoveries of the analytes after suppression (93-99% recovery) and significantly reduced band broadening during suppression. The new suppressor has been shown to perform well under both isocratic or gradient elution conditions.
Source: Journal of Chromatography A, Available online 11 February 2012
Naama Karu, Greg W. Dicinoski, Melissa Hanna-Brown, Kannan Srinivasan, Christopher A. Pohl, ...
For the hyphenation of ion chromatography to nebulising detectors or mass spectrometry, suppression of the non-volatile ionic eluent to water is a required step to avoid elevated detector baselines. Presented here is a study of three new designs of electrolytic suppressors, incorporating high ion-exchange capacity screens and high ion-exchange capacity membranes in different thickness and composition. These designs aim to minimise hydrophobic interactions of the suppressor with organic analytes and to provide higher compatibility with eluents containing acetonitrile. In comparison with a commercially-available electrolytic suppressor and also a commercially available chemical suppressor, the new high-capacity suppressor showed superior performance, exhibiting minimal interactions with a test set of analytes under the examined conditions. This led to the attainment of high recoveries of the analytes after suppression (93-99% recovery) and significantly reduced band broadening during suppression. The new suppressor has been shown to perform well under both isocratic or gradient elution conditions.
Highlights
► New high capacity IC suppressors have been evaluated. ► Reduced interactions with hydrophobic analytes were observed. ► Analyte peak shapes after suppression were improved ► Analyte recoveries of 95-99% were observed after suppressionInvestigation of Retention Behavior of Polychlorinated Biphenyl Congeners on 18 Different HRGC Columns using Molecular Surface Average Local Ionization Energy Descriptors
11 February 2012, 22:28:43
Publication year: 2012
Source: Journal of Chromatography A, Available online 11 February 2012
Raouf Ghavami, Bakhtyar Sepehri
In this paper, based on the general interaction properties function (GIPF) family descriptors computed at the B3LYP/6-31G* level in Gaussian98 software, a significant quantitative structure-retention relationships (QSRRs) models for the high resolution gas chromatographic relative retention time (HRGC-RRT) of all PCB congeners on 18 different HRGC capillary columns were constructed by using multiple linear regression (MLR) analysis, following the guidelines for development and validation of QSRR models. By means of the elimination selection stepwise regression algorithms, the molecular surface average local ionization energy was selected as one-parameter univariate linear regression to develop a QSRR model for prediction of GC-RRT of PCBs on each stationary phase. The accuracy of all developed models was confirmed using different types of internal and external procedures. A successful interpretation of the complex relationship between HRGC-RRTs of PCBs and the chemical structures was achieved by QSRR.
Source: Journal of Chromatography A, Available online 11 February 2012
Raouf Ghavami, Bakhtyar Sepehri
In this paper, based on the general interaction properties function (GIPF) family descriptors computed at the B3LYP/6-31G* level in Gaussian98 software, a significant quantitative structure-retention relationships (QSRRs) models for the high resolution gas chromatographic relative retention time (HRGC-RRT) of all PCB congeners on 18 different HRGC capillary columns were constructed by using multiple linear regression (MLR) analysis, following the guidelines for development and validation of QSRR models. By means of the elimination selection stepwise regression algorithms, the molecular surface average local ionization energy was selected as one-parameter univariate linear regression to develop a QSRR model for prediction of GC-RRT of PCBs on each stationary phase. The accuracy of all developed models was confirmed using different types of internal and external procedures. A successful interpretation of the complex relationship between HRGC-RRTs of PCBs and the chemical structures was achieved by QSRR.
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