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Amino acids are widely distributed in biological fluids and involved in many biological processes, such as the synthesis of proteins, fatty acids, and ketone bodies. The altered levels of amino acids in biological fluids have been found to be closely related to several diseases, such as type 2 diabetes, kidney disease, liver disease, and cancer. Therefore, the development of analytical methods to measure amino acid concentrations in biological samples can contribute to research on the physiological actions of amino acids and the prediction, diagnosis and understanding of diseases. This review describes the analytical methods reported in 2012–2016 that utilized liquid chromatography and capillary electrophoresis coupled with ultraviolet, fluorescence, mass spectrometry, and electrochemical detection. Additionally, the relationship between amino acid concentrations and several diseases is also summarized. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the separation efficiency of a core–shell particle column was compared with particle-packed and monolithic silica columns, which showed that the core–shell particle column had a smaller theoretical plate height and that its separation efficiency was not affected significantly by the increase in flow rate. A fast HPLC method using a core–shell particle column was developed for the determination of amino acids. 4-Fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was used as a fluorescence derivatization reagent for amino acids, followed by separation on a core–shell Kinetex C18 column. The analysis time for 21 NBD-amino acids was within 7min, which was faster than that in our previous studies with conventional particle-packed columns or monolithic silica columns. The linearities of the calibration curves for all the amino acids were found to be good over a range of injection amounts from 40fmol to 40pmol. The accuracies for the amino acid determinations were 90.9–107%. The method was proved to have potential for the fast determination of amino acids in biological samples. [Copyright &y& Elsevier]

Abstract: A fast HPLC method using a monolithic silica column was developed for the measurement of amino acids. The amino acids were pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and separated on a monolithic silica column (MonoClad C18-HS, 250mm×3mm I.D.). The separation of 19 NBD-amino acids was achieved within 18min, which was only one-fifth of the time taken by the methods using a conventional particle-packed column, with the gradient elution of a mobile phase at the flow rate of 1.4mL/min. The sensitivity was good with a limit of detection for the individual amino acids ranging from 2.94 to 53.4fmol. The calibration curves for all the amino acids were found to be linear in the range of 200fmol to 20pmol with correlation coefficients of 0.997 or better. The analytical method was successfully applied to determine the amino acids in a mouse plasma sample. [Copyright &y& Elsevier]