Suitable analysis of α-amino acids by a direct combination of thin-layer chromatography and matrix-assisted laser desorption/ionization mass spectrometry in conjunction with post-chromatographic fixed-charge derivatization.

On-spot fixed-charge derivatization has been suggested for the modification of α-amino acids for their analysis by thin layer chromatography/matrix-assisted laser desorption ionization (TLC/MALDI) mass spectrometry. The approach was based on post-chromatographic treatment of separated analytes by tris(2,6-dimethoxyphenyl)methenium salt and triethylamine. The reaction proceeded smoothly in mild conditions and gave rise to pink-red colored derivatives, containing permanent positive charge. Their MALDI mass spectra, recorded directly from TLC plates, revealed intense peaks corresponding to decarboxylated cationic parts. All derivatives are characterized by high ionization efficiency, which indicates the high sensitivity of the developed method for analyzing amino acids. Applicability of the method to analysis of amino acids was demonstrated on artificial mixtures and dietary supplement.

An approach to analysis of primary amines by a combination of thin-layer chromatography and matrix-assisted laser desorption ionization mass spectrometry in conjunction with post-chromatographic derivatization.

On-spot derivatization has been suggested for the modification of primary amine containing compounds for their analysis by thin-layer chromatography hyphenated with matrix-assisted laser desorption ionization mass spectrometry. The proposed approach was based on post-chromatographic treatment of separated analytes inside the chromatographic zones on the thin-layer chromatography plates by tris(2,6-dimethoxyphenyl)methilium reagent. The derivatives, containing permanent positive charge, reveal exceptionally intense peaks of their cationic moieties and high signal/noise ratio in mass spectra recorded directly from the plates. The method was tested on a series of aliphatic, aromatic, and amine-containing pharmaceuticals.

Suitable in-situ derivatization of alcohols by reaction with basic amines in Direct Analysis in Real Time mass spectrometry.

This work highlights the discovered in-situ analytical reaction between primary/secondary alcohols and nitrogenous bases (pyridine, quinoline) that involves the substitution of hydroxyl groups for nitrogen-containing charged species and proceeds in an ionization region of Direct Analysis in Real Time mass spectrometry (DART-MS) instrument at gas stream temperature of 150-450 °C. Resulted cations provide strong signals in mass spectra and this ensures high sensitivity of the analysis. Collision induced dissociation of such precursor ions gives rise to characteristic and simple fragmentation mass spectra revealing mainly protonated nitrogenous bases and carbonium cations resulting from the elimination of neutral nitrogen-containing bases. The dependence of signal response on gas stream temperature was elucidated. It was also found that, independently of gas stream temperature, high volatility low-molecular weight alcohols did not demonstrate characteristic DART spectra owing to a high rate of desorption/evaporation which does not provide sufficient probability of the reaction. To the best of our knowledge, this type of specific reactions in a plasma-based source of DART mass spectrometer is reported for the first time. It represents a new and interesting derivatization approach providing a rapid and sensitive complement method for the detection and identification of individual monools of various origin, profiling plant sterols and other steroid alcohols in different matrices.

Post-chromatographic fixed-charge derivatization for the analysis of hydroxyl-containing compounds by a combination of thin-layer chromatography and matrix-assisted laser desorption/ionization mass spectrometry.

A simple and convenient on-spot derivatization has been suggested for the modification of hydroxyl-containing compounds for their analysis by thin layer chromatography/matrix-assisted laser desorption ionization mass spectrometry (TLC/MALDI). The proposed approach was based on post-chromatographic acylation of separated analytes by 3-bromopropionyl chloride with simultaneous quaternization of pyridine. In contrast to the initial alcohols not ionizable in TLC/MALDI conditions, the derivatives, containing permanent positive charge, revealintense peaks of their cationic moieties in MALDI mass spectra recorded directly from TLC plates. The method was tested on a series of mammalian and plant sterols, phenols and terpene alcohols.

Composite glycerol/graphite/aromatic acid matrices for thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry of heterocyclic compounds.

New composite matrices have been suggested for the analysis of mixtures of different synthetic organic compounds (N-containing heterocycles and erectile dysfunction drugs) by thin layer chromatography/matrix-assisted laser desorption ionization time-of-flight mass spectrometry (TLC/MALDI-TOF). Different mixtures of classical MALDI matrices and graphite particles dispersed in glycerol were used for the registration of MALDI mass spectra directly from TLC plates after analytes separation. In most of cases, the mass spectra possessed [M+H]+ ions; however, for some analytes only [M+Na]+ and [M+K]+ ions were observed. These ions have been used to generate visualized TLC chromatograms. The described approach increases the desorption/ionization efficiencies of analytes separated by TLC, prevent spot blurring, simplifies and decrease time for sample preparation.

Medición de la fuga capilar en la preeclampsia-eclampsia / Measurement of capillary fuge in pre-eclampsia-eclampsia

Introducción: se proponen dos parámetros para estimar la fuga capilar que se presenta en pacientes con preeclampsia grave y eclampsia, cuando se alteran las fuerzas de Starling.Objetivo: reportar los valores de la PCOc y el IB en mujeres con preeclampsia grave y eclampsia, asimismo compararlo con embarazo normal.Pacientes y método: se estudiaron prospectivamente los valores de la PCOc y el IB en 87 pacientes con preeclampsia grave y eclampsia (grupo A); comparandolo con 50 pacientes con embarazo normal (grupo B). La PCOc se calculó de acuerdo con la fórmula de Landis-Pappenheimer y el IB se obtuvo de dividir el resultado entre la PCOc y la PAM.Resultados: la PCOc fue de 15.3 ñ 4.5; el IB de 0.11 ñ 0.03 en el grupo A, 24.0 ñ 4.4 y 0.27 ñ 0.03 en el grupo B, (p < 0.005 y p = 0.300 respectivamente).Conclusiones: la PCOc y el IB disminuyen significativamente en la preeclampsia-eclampsia y se propone su utilización como índices cuantitativos de fuga capilar.