Analysis of Biological Samples in a Contemporary Laboratory Practice (Review)

Abstract

Introduction. In the present publication highlights the key points of the main stages of development of methods for determining trace amounts of drugs and metabolites in biological samples using chromatographic and chromatography-mass spectrometry methods. The main sources of errors are specified. The main attention is paid to chromatography-mass spectrometry, which is the basic method of analysis of small molecules in biological samples. Examples from literary sources and authors' own practice are given.Text. The review highlights some of the practical issues of preparation of calibration samples, method of increasing the stability of the sample at the stage of sampling and plasma preparation. In particular, the influence of various anticoagulants on the accuracy of the analysis is reflected. Specify the method of reducing back conversion of some metabolites of carboxyl-containing drugs to parent compound to prevent overestimation of the results of quantitative determination. Some methods of sample preparation, which have become widespread recently, are noted. For example, solid supported liquid-liquid extraction, based on the extraction of the component of interest from the water sample into the liquid layer distributed on a solid high-polar carrier, followed by eluting by a system of non-polar solvents that do not mix with this layer. Recommendations on the use of internal standards, the preparation of the mobile phase for HPLC, on chromatographic separation, validation techniques are given. In the section «Mass spectrometric detection» features of preparation of a mobile phase for chromatography-mass spectrometry experiments are given. The questions of carry-over reduction, ion suppression, matrix effect are covered. The phenomenon of cross-talk in the study of drug metabolism by chromatography-mass spectrometry is discussed. It consists in the mutual distortion of the mass spectrometric response, when the same mass fragments are formed from different ions-precursors. Features of development of techniques for high-performance pharmacokinetic screening are given.Conclusion. The authors hope that the presented material will be useful for scientists and specialists in the field of pharmacokinetics, biomarker discovery and clinical analyses.