Enhancing LC/ESI-MS/MS Throughput for Plasma Bile Acid Assay by Derivatization-based Sample-Multiplexing.

Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) enables the accurate and precise quantification of various analytes at very low concentrations, but it has room for improvement in analysis throughput. Multiplexing of samples in the same injection could be a promising procedure for enhancing the analysis throughput. This could be achieved by derivatization of the multiple samples with multiple isotopologous reagents.

A Method for Quantification of Tetrahydroglucocorticoid Glucuronides in Human Urine by LC/MS/MS with Isotope-coded Derivatization.

The determination of urinary tetrahydroglucocorticoid (THGC) glucuronides might prove helpful in the diagnosis, pathophysiological analysis and assessment of the therapeutic efficacy of the diseases caused by abnormal cortisol secretion. We developed and validated a method for the determination of the THGC glucuronides in human urine using liquid chromatography/electrospray ionization (ESI)-tandem mass spectrometry not requiring enzymatic hydrolysis. The method employed a derivatization using an ESI-enhancing reagent for carboxylic acids, 1-[(4-dimethylaminophenyl)carbonyl]piperazine (DAPPZ), and its isotopologue, H-DAPPZ.