An LC/MS/MS method for quantifying testosterone and dehydroepiandrosterone sulfate in four different serum samples during a single run.

Simultaneous measurements of the circulating testosterone (TS) and dehydroepiandrosterone sulfate (DHEAS) are deemed to be helpful for the assessment of men's health. Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) is the most reliable methodology for this purpose; however, it has room for improvement in analysis throughput. In this study, a quadruplicate of the Girard reagents was used to develop an LC/ESI-MS/MS method capable of quantifying TS and DHEAS in four different serum samples in a single run. The four serum samples were separately pretreated, derivatized with one of four Girard reagents, and then combined. The LC/ESI-MS/MS analysis of the combined sample provided the androgen concentrations of four serum samples in parallel. The method had practical measuring ranges, in which good precision and accuracy, as well as negligible matrix effects were verified. The speed-up capability of the developed method was evaluated through the analysis of ten batches of serum samples (total 40 samples); the method saved a 60% post-pretreatment analysis time compared to the non-derivatization method for 40 samples.

Quantitative MALDI-MS/MS assay for serum cortisol through charged derivatization.

Cortisol (CRT), the main glucocorticoid in humans, plays a crucial role in many physiological processes, therefore, the measurement of its serum level is of great clinical significance. Matrix-assisted laser desorption/ionization-tandem mass spectrometry (MALDI-MS/MS) might be an effective approach for the quantification of CRT in serum due to its attractive properties, i.e., high specificity, ease of use, ruggedness and rapid analysis. In this study, we developed a method to quantify the serum CRT by MALDI-MS/MS. This method employed the derivatization using a Girard-type reagent, 1-(hydrazinocarbonylmethyl)isoquinolinium chloride, which compensated for the lack of sensitivity. This method enabled the reproducible quantification of the serum CRT using a 20-µL sample (intra- and inter-assay relative standard deviations, 7.4% or lower), and the measurable range was 25-500 ng/mL. The serum CRT concentrations determined by the newly-developed MALDI-MS/MS method agreed well with those by liquid chromatography/electrospray ionization-MS/MS or electrochemiluminescence immunoassay. The MALDI-MS/MS method was used for the analysis of peripheral venous serum samples of healthy subjects and adrenal venous serum samples of patients with primary aldosteronism, and satisfactory results were obtained.