This review is focused on planar chromatography hyphenated with mass-spectrometric detection for analysis of low-molecular-mass solutes. Various kinds of hyphenations are discussed with attention paid to the preparation of thin layer plates suited both for the mass-spectrometric detection of the resolved solutes direct from thin-layer plates and for indirect mass-spectrometric detection of the resolved solutes, performed by scraping, extracting, purifying, and concentrating the analyte from the thin-layer chromatography plate. Plates with monolithic layers are relatively new for thin-layer chromatography but they can successfully be combined with mass-spectrometric technique in a pursuit of comprehensive local sample composition information. Preparation of monolithic layers of different porosity and structure based on organic, inorganic, and composite materials is illustrated together with examples of successful separation and detection of low-molecular-mass solutes by means of matrix-assisted and surface-assisted laser desorption mass spectrometry.
Monolithic layers prepared by the copolymerization of ethylene dimethacrylate and glycidyl methacrylate and deposited onto the surface of glass and silicon plates were investigated as thin‐layer chromatography separation media in hyphenated thin‐layer chromatography with matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) analysis. Varying composition of the polymerization mixture and polymerization conditions layers of different porosities and MALDI‐MS compatibility were synthesized. Compatibility with MALDI‐MS was tested using polyethylene glycol and it was demonstrated that layers prepared without glycidyl methacrylate are not compatible with MALDI‐MS and do not allow obtaining any mass spectra. Best results were achieved with layers containing 19 to 29% glycidyl methacrylate. These layers allow the measurement of mass spectra without additional depositing matrix compounds supplying mass spectra almost “clean” in low molar mass range.
Monolythic medium-polar capillary columns based on pentaerythritol tetraacrylate were optimized for separation of peptides. The synthesis temperature and time, the fraction of monomer in the initial polymerization mixture, and the nature of alcohol contained in the complex porogen were chosen as optimization parameters. The highest efficiency was attained for columns obtained with 33 and 34% monomer at a polymerization time of 75 min and a temperature of 75°C. The columns with the optimum structure were effective in separation of a model mixture of five peptides. The sensitivity of the method was 200 ng of peptide per column.
Показана возможность создания монолитных пластин, содержащих в своей структуре функциональные группы, способные выполнять роль МАЛДИ матриц, продемонстрированы первые результаты по десорбции/ионизации соединений с массами порядка 400 Да. Приготовлены монолитные пластины на основе (со)полимеров глицидилметакрилата и этиленгликоля диметакрилата с содержанием первого от 0 до 29% и стирола и дивинилбензола с содержанием стирола от 0 до 35%. Наилучшие результаты удалось получить для пластин с содержанием глицидилметакрилата от 19 до 29 % и с содержанием стирола 5-20%. Отмечено, что отсутствие монофункционального мономера в полимеризационной смеси приводит к подавлению ионизации аналитов и невозможности использования таких пластин в режиме МАЛДИ-МС. Предложенный в работе метод получения МАЛДИ-МС-ТСХ спектров позволяет исключить один из наиболее трудоемких этапов процесса, связанный с приготовлением и нанесением МАЛДИ матрицы на ТСХ платины.
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