High performance liquid clinical development

Gas chromatography is a rapid, sensitive and specific method with excellent chromatographic characteristics suitable for routine clinical analysis of amino acids. When combined with mass spectrometry (GC-MS), it permits the investigator to elucidate the structures of prepared derivatives, and thus their unequivocal identification. However, the recent rapid development of high-performance liquid chromatography has provided an excellent alternative and/or complementary procedure for the analysis of ammo acids... 

The value of electrochemical detection following high performance liquid chromatography is compared with that of the more widely used optical methods of detection. Its advantages are illustrated by its application to three areas of clinical chemistry that had previously posed analytical problems. Its sensitivity allowed its use for the measurement of plasma catecholamines. Its selectivity was employed to produce rapid methods for the determination of urinary levels of catecholamine and tryptophan metabolites. Finally, its value for the estimation of urinary oxalic acid is shown. Future developments such as increasing the range of detectable compounds by derivatization are briefly discussed. 

The fast-gradient method, in contrast, retains analytes on-column until well after the solvent front has eluted. Overall sample throughput is increased with fast-gradient methods due to reduced analytical run time, decreased method development time, and fewer repeat analyses. Onorato et al. [90] used a multiprobe autosampler for parallel sample injection, short, small-bore columns, high flow rates, and elevated HPLC column temperatures to perform LC separations of idoxifene and its metabolite at 10 s/sample. Sample preparation employed liquid liquid extraction in the 96-well format. An average run time of 23 s/sample was achieved for human clinical plasma samples. 

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