Quantification of testosterone and epitestosterone in human urine samples by stir bar sorptive extraction – thermal desorption – gas chromatography/mass spectrometry: Application to HIV‐positive urine samples

Abstract

A simple method is described for the measurement of testosterone (T) and epitestosterone (ET) in human urine samples. The deconjugated steroids were extracted directly from the samples by stir bar sorptive extraction (SBSE) and derivatized in situ on the stir bar by headspace acylation prior to thermal desorption and GC/MS. Extraction and derivatization parameters, namely salt addition, temperature, and time, were optimized to improve the recovery of T and ET by SBSE. The limits of quantification (S/N 10) were 0.9 ng/mL for T and 2.8 ng/mL for ET. Quantification of the steroids in urine samples was performed using standard addition to avoid the influence of matrix effects. The method was applied for the measurement of urinary T and ET in a group of healthy volunteers and HIV+ patients. Decreased levels of T were detected in the HIV+ group, whereas the excretion of ET was comparable for the two groups. Further clinical research is required to elucidate the biomarker significance of the T/ET ratio in HIV infection.

Highly sensitive and selective analysis of urinary steroids by comprehensive two-dimensional gas chromatography combined with positive chemical ionization quadrupole mass spectrometry

“…Four different concentration ranges were used to create calibration curves for the steroids, based on their normal endogenous concentrations in urine 36, 37 . The LOQ values achieved by full scan GC×GC– qMS for the twelve endogenous steroids were comparable to GC-MS used with SIM reported in other work 38, 39 . The LOQ repeatability for both EI and PCI-NH 3 were less than 5% RSD, and the accuracy, reported as the deviation from the mean value, was better than ±18% for all the steroids tested.…”

Stir-bar sorptive extraction: 15 years making sample preparation more environment-friendly

“…Some reports dealing with several derivatization agents can be consulted in literature [10,17,[49][50][51][52][53][54][55][56]. Although the derivatization approach has been used to overcome the lack of efficiency of SBSE(PDMS) for the most polar solutes, it is very limited to a few specific derivatization agents, depending on the chemical properties of the analytes and the type of reaction to be carried out.…”

Determination of epitestosterone in human urine by off-line immunoaffinity solid-phase extraction coupled with high performance liquid chromatography

“…The cleanup methods include solidphase extraction (SPE) [31,32], liquid-liquid extraction (LLE) [33], and stir bar sorption extraction [34]. Immunoaffinity extraction is a special SPE based on the highly specific interaction between antigen and antibody.…”