Features of gas chromatographic analysis of thermally unstable compounds.

Confirming the stability of analytes during gas chromatographic (GC) analysis is an important criterion, especially for previously uncharacterized compounds. However, the variations of absolute peak areas at different injector temperatures usually do not allow us to reveal the thermal instability of analytes during GC analysis. Such variations may be caused by peak area known discrimination typical for using capillary columns, especially at low split injection.

Evidence for the Hydration of Some Organic Compounds during Reverse-Phase HPLC Analysis.

Some polar analytes (X) can reversibly form hydrates in water-containing eluents under the conditions of reversed-phase HPLC analysis, X + H2O ⇄ X × H2O. One of the methods to detect their formation is the recurrent approximation of the net retention times of such analytes, tR(C + ΔC) = atR(C) + b, where ΔC = const is the constant step in the variation of the organic modifier content of an eluent. These dependencies are linear if hydrates are not formed, but in the case of hydrate formation, they deviate from linearity under high water content.

Unusual Regularity in GC Retention of Simple Amino Acid Derivatives.

Background: Application of simple regularities and general principles along with direct use of reference gas chromatography retention index data for reliable structure determination of compounds can be enhanced by determination of new regularities that are specific to certain structural elements.

Objective: Revelation and interpretation of an anomaly in the elution order of alkyl esters of alkoxycarbonyl derivatives of glycine and alanine on standard and semi-standard non-polar phases.

Method: Preliminary derivatization of amino acids to alkyl esters of N-alkoxycarbonyl analogs and interpretation of their gas chromatographic characteristics.

Comparative gas chromatographic/mass spectrometric characterization of di- and trialkyl phosphites.

Rationale: Homologous series of alkyl esters of phosphorus-containing acids, namely, dialkyl phosphonates (synonym: dialkyl phosphites) and trialkyl phosphites, were characterized by electron ionization (EI) mass spectra and gas chromatographic retention indices (GC RI) on semi-standard non-polar stationary phases. It is confirmed that GC/MS characterization of any sets of homologues should not be restricted to independent registration of these analytical parameters. Their joint processing in the form of so-called homologous increments of GC RIs means, firstly, a novel way of evaluating the chromatographic polarity of analytes and, secondly, a new algorithm for the prediction of their molecular weights if no peaks of molecular ions are registered in the mass spectra.

Application of lanthanum stearate monolayers as a metal-affinity sorbent for the selective sorption of soman adducts to human serum albumin.

A new metal-affinity sorbent based on lanthanum stearate monolayers has been developed and characterized. The prospect of its application to specific extraction of organophosphorous compound (OP) adducts of blood proteins was demonstrated. For this, the patterns of soman adducts of human serum albumin (HSA) were comprehensively characterized by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS).