Tutorial review on validation of liquid chromatography–mass spectrometry methods: Part I

This is the part I of a tutorial review intending to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC–MS) and discuss specific issues that arise with MS (and MS/MS) detection in LC (as opposed to the “conventional” detectors). The Part I briefly introduces the principles of operation of LC–MS (emphasizing the aspects important from the validation point of view, in particular the ionization process and ionization suppression/enhancement); reviews the main validation guideline documents and discusses in detail the following performance parameters: selectivity/specificity/identity, ruggedness/robustness, limit of detection, limit of quantification, decision limit and detection capability. With every method performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations are given, how to determine it, specifically in the case of LC–MS methods.     

Evaluation of the separation performance of polyvinylpyrrolidone as a virtual stationary phase for chromatographic NMR

Polyvinylpyrrolidone (PVP) was used as a virtual stationary phase to separate p‐xylene, benzyl alcohol, and p‐methylphenol by the chromatographic NMR technique. The effects of concentration and weight‐average molecular weight (Mw) of PVP, solvent viscosity, solvent polarity, and sample temperature on the resolution of these components were investigated. It was found that both higher PVP concentration and higher PVP Mw caused the increase of diffusion resolution for the three components. Moreover, the diffusion resolution did not change at viscosity‐higher solvents. Moreover, the three components showed different resolution at different solvents. As temperature increased, the diffusion resolution between p‐xylene and benzyl alcohol gradually increased, and the one between p‐xylene and p‐methylphenol slightly increased from 278 to 298 K and then decreased above 298 K. It was also found that the polarity of the analytes played an important role for the separation by affecting the diffusion coefficient. Copyright © 2014 John Wiley & Sons, Ltd.     

Organic Compounds in Surface and Deep Antarctic Snow

Abstract

Eight surface snow samples taken during the 1987/88, 1988/89 and 1990/91 Italian Antarctic Expeditions and six samples collected at different depths from two dissimilar sites during the 1990/91 Expedition, were analyzed for the non-chlorinated organic content using the GC capillary columns technique and GC-MS. Several biogenic and anthropogenic classes of organic compounds were identified and quantitatively determined. The data obtained give a more complete picture of the pollution level in Antarctica.     

Analysis of Organic Compounds in Antarctic Snow and Their Origin

Abstract

Organic compounds extractable with n-hexane were identified and quantitatively determined in pack, surface and deep snow samples taken at different depths and collected at several altitudes above sea level from Antarctica during the 1993/94 Italian expedition. The comparison between the composition of organic compounds in snow and the ones in pack and sea-water samples pointed out that the three matrices substantially contain the same biogenic and anthropogenic organic compounds. The contribution of marine aerosol to organic content in the snow is confirmed by the enrichment ratios calculated for the more representative classes of identified compounds (n-alkanes, phthalates and low molecular weight alkylbenzenes). The changes in the composition of organic compounds in snow as the altitude increases seem to depend on the dimensional spectrum of the aerosol. Thus, smallest particles, richest in surfactant material, reach the highest altitudes.     

Concise Synthesis of Photocleavable Molecular Tag for Laser Desorption Ionization Mass Spectrometry via Fries Reaction

Abstract

A new synthetic route for the photocleavable molecular tag for laser desorption ionization mass spectrometry (LDI-MS) was achieved using the Fries reaction of 2,6-dimethylphenyl ester as its key reaction. Zirconium chloride was used as uniquely efficient adjuvant to promote the reaction. The molecular tag was obtained in five steps without chromatographic purification.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

苯磺酸氨氯地平对映体在Chiralcel OJ柱上的色谱保留及拆分特性

在Chiralcel OJ手性柱上对苯磺酸氨氯地平对映体进行分离研究.考察了在正己烷流动相体系中,不同碳数、不同立体结构的醇类添加剂以及不同醇含量对分离结果的影响,同时还考察了流速及柱温对分离的影响.并通过色谱保留及热力学行为研究对药物手性识别机理进行了探讨.结果表明,在正己烷-异丙醇(90:10,体积比)为流动相,流...     

Determination of Ciprofloxacin in Human Plasma and Urine by Precolumn Derivatization High Performance Liquid Chromatography with Fluorescence Detection

A sensitive, simple and selective high‐performance liquid chromatographic (HPLC) method was developed for the determination of ciprofloxacin in biological fluids. The method is based on the reaction between the drug and 4‐chloro‐7‐nitrobenzofurazan (NBD‐Cl) in borate buffer of pH 9.0 to yield a highly fluorescent derivative that is measured at 535 nm after excitation at 464 nm. The calibration curves were linear over the concentration ranges of 25–3000 and 50–3000 ng·mL^?1 for plasma and urine, respectively. The mean recovery of ciprofloxacin from plasma and urine was 98.37% and 98.40%, respectively. The method was found to be sensitive, precise, accurate, and reproducible. All of the validation parameters were within the acceptance range.     

多环芳香硫化合物的定量结构-气相色谱保留指数关系

应用分子电性距离矢量(MEDV)对114个多环芳香硫化合物(PASHs)进行结构表征,通过多元线性回归建立了PASHs的气相色谱保留指数与MEDV参数之间的定量结构-保留值关系模型;同时采用逐步回归分析进行变量筛选,继而以留一法交互检验对所得优化模型进行预测能力评价,所建立的模型的相关系数为0.9947,交互检验相关系数为0.9940,表明该优化模型具有良好的稳定性和预测能力。此外,通过将样本集按2:1分成校准集和测试集预测,统计分析结果显示所建的模型具有良好的相关性和稳定性。本文所建的定量结构-保留值关系(QSRR)模型为预测PASHs的气相色谱保留指数提供了一个便捷有效的新方法。     

基于微流控芯片的色谱系统的研究进展及其应用

近年来,基于微流控芯片的色谱技术研究取得了快速发展。本文对微流控芯片上色谱柱的加工方法、泵阀驱动控制装置的设计、集成及联用色谱系统的研制及其应用等方面予以综述,涉及文献66篇。     

Preparation of stir cake sorptive extraction based on polymeric ionic liquid for the enrichment of benzimidazole anthelmintics in water,honey and milk samples

In this work, a new stir cake sorptive extraction (SCSE) using polymeric ionic liquid monolith as sorbent was prepared. The sorbent was obtained by in situ copolymerization of an ionic liquid, 1-allyl-3-methylimidazolium bis[(trifluoro methyl)sulfonyl]imide (AMII) and divinylbenzene (DB) in the presence of N,N-dimethylformamide. The influence of the content of ionic liquid and the porogen in the polymerization mixture on extraction performance was studied thoroughly. The physicochemical properties of the polymeric ionic liquid were characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. The usefulness of SCSE–AMIIDB was demonstrated by the enrichment of trace benzimidazole anthelmintics. Several parameters affecting the extraction efficiency were investigated, and under the optimized conditions, a simple and effective method for the determination of trace benzimidazoles residues in water, milk and honey samples was established by coupling SCSE–AMIIDB with high performance liquid chromatography/diode array detection (SCSE–AMIIDB–HPLC/DAD). Results indicated that the limits of detection (S/N = 3) for target compounds were 0.020–0.072 μg L⁻¹, 0.035–0.10 μg L⁻¹ and 0.026–0.076 μg L⁻¹ in water, milk and honey samples, respectively. In addition, an acceptable reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations (RSD) of less than 9% and 11%, respectively. Finally, the established AMII–SCSE–HPLC/DAD method was successfully applied for the determination of benzimidazoles residues in milk, honey and environmental water samples. Recoveries obtained for the determination of benzimidazole anthelmintics in spiking samples ranged from 70.2% to 117.6%, with RSD below 12% in all cases.