Advances in Amino Acid Analysis

amino acid profiling in routine clinical analysis (1,2). As analysts started using capillary electrophoresis (CE) in the 1990s, they were able to successfully use most of the popular reagents from LC analyses in electromigration techniques. The remarkable progress in detection technologies — such as diodearray ultraviolet (UV), laser-induced fluorescence, evaporative light-scattering, and mass spectrometry (MS) detection with various ionization principles — provided new opportunities in amino acid determination. The advances in evaporative light-scattering and MS techniques restored new interest in native amino acid analyses. Despite the remarkable improvements in separation and detection technology, sample preparation before analysis remains an integral and often the most time-consuming part of the methodology. Because of the matrix complexity, preparation of biological samples such as body fluids usually is difficult and laborious, so that even excellent separation and detection methods may fail to deliver the performance and ruggedness required for routine use. This fact is recognized more often in application laboratories but seldom in the academic community. Expedient sample preparation, therefore, is of primary importance in routine applications, and the lack of it is the possible reason that a limited number of robust, userfriendly methods for analyzing amino acids The authors briefly review current strategies of amino acid analysis and present a novel approach to a simplified sample preparation of body fluids. Their procedure involves two consecutive extraction steps: a solidphase step and a liquid–liquid step, during which the analytes are selectively isolated and rapidly alkylated while being transferred into an organic phase with a high degree of purity. The total time of sample preparation and gas chromatography (GC) analysis is approximately 15 min. The derivatives can be analyzed by GC with flame ionization, nitrogen–phosphorus, or mass spectrometry detection or by liquid chromatography with mass spectrometry detection, all of which give this procedure a versatility lacking in other current techniques. Advances in Amino Acid Analysis