The quantification of the circulating dehydroepiandrosterone sulfate (DHEAS) might be of diagnostic help for several diseases. For the DHEAS quantification, LC/ESI–MS/MS has the advantage of a high specificity compared with immunoassay, whereas LC/ESI–MS/MS has room to improve the analysis throughput. One of the promising solutions to enhance the analysis throughput is sample‐multiplexing in the same injection, which can reduce the total LC/ESI–MS/MS run time. In this study, a quadruplex LC/ESI–MS/MS method was developed to quantify DHEAS in four different serum samples in a single run. After the four samples were separately deproteinized and derivatized with one of four Girard reagents (Girard reagent T, P and their isotopologs), the resulting samples were mixed, then injected into the LC/ESI–MS/MS. The applicability and advantage of the developed method were evaluated based on the analysis of nine batches of serum samples from healthy subjects (total 36 samples). The limit of quantitation was 0.050 μg/ml, which was sensitive enough for clinical laboratory use. The method was precise (intra‐ and inter‐assay RSDs ≤ 3.6%), accurate (94.4–108.1%) and robust for the matrix effects. The analysis time was also shortened by about 60% for 36 samples by the introduced method compared with the conventional method.
In this study, we developed an analytical method using LC-MS/MS for the simultaneous determination of five bile acids (BAs) that have been recently reported as candidate diagnostic biomarkers for Alzheimer's disease (AD) or AD related factors in the brain.The measurement of BAs in the brains of healthy mice led to the determination of candidate diagnostic markers for AD, such as cholic acid and deoxycholic acid, and other bile acids, such as chenodeoxycholic acid noted for the ameliorating effect on the symptoms of AD.Significant positive correlations were observed between the brain and plasma concentrations of four BAs in healthy young mice. These results indicate that the BA level in the brain may be estimated by the corresponding BA level in the plasma. Thus, our study suggested that the proposed method for the analysis of the five bile acids would aid in the diagnosis of AD or in studies that use AD model mice.
Simultaneous measurement of the circulating testosterone (TS) and dehydroepiandrosterone sulfate (DHEAS) is 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, 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, and negligible matrix effects were verified. The speed-up capability of the developed method was evaluated through the analysis of 10 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.
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