Simultaneous determination of multiple androgens in mice organs with liquid chromatography tandem mass spectrometry

Development of an LC-MS Targeted Metabolomics Methodology to Study Proline Metabolism in Mammalian Cell Cultures

A growing interest in metabolomics studies of cultured cells requires development not only untargeted methods capable of fingerprinting the complete metabolite profile but also targeted methods enabling the precise and accurate determination of a selected group of metabolites. Proline metabolism affects many crucial processes at the cellular level, including collagen biosynthesis, redox balance, energetic processes as well as intracellular signaling. The study aimed to develop a robust and easy-to-use targeted metabolomics method for the determination of the intracellular level of proline and the other two amino acids closely related to proline metabolism: glutamic acid and arginine. The method employs hydrophilic interaction liquid chromatography followed by high-resolution, accurate-mass mass spectrometry for reliable detection and quantification of the target metabolites in cell lysates. The sample preparation consisted of quenching by the addition of ice-cold methanol and subsequent cell scraping into a quenching solution. The method validation showed acceptable linearity (r > 0.995), precision (%RSD < 15%), and accuracy (88.5–108.5%). Pilot research using HaCaT spontaneously immortalized human keratinocytes in a model for wound healing was performed, indicating the usefulness of the method in studies of disturbances in proline metabolism. The developed method addresses the need to determine the intracellular concentration of three key amino acids and can be used routinely in targeted mammalian cell culture metabolomics research.

A highly sensitive LC-MS/MS method for the simultaneous quantitation of serum androstane-3α, 17β-diol and androstane-3β, 17β-diol in post-menopausal women

Sensitive and accurate measurement of androstane-3β,17β-diol and androstane-3α,17β-diol in the circulation is important for clinical research and accurate clinical diagnosis. This report describes a highly sensitive, specific, precise and reliable assay for the simultaneous accurate measurement of serum androstane-3α,17β-diol and androstane-3β,17β-diol in postmenopausal women. The LLOQ of 1 pg/mL has been achieved with nicotinic acid derivatization, which is superior to picolinic acid by a factor of 5 to 10 in terms of signal to noise ratio. The difference is attributed to the higher acidity of picolinic acid which forms a more stable intermediate, thus decreasing derivatization efficiency. Potential interference from androstane-3α, 17α-diol, androstane-3β, 17α-diol, and 5-androstenediol has been well separated from the two target diols. The high level of specificity has been determined by well-developed chromatography and ion ratio monitoring. A good linearity in the range of 1 pg/mL to 200 pg/mL (0.03 pg to 6 pg on column) was obtained for both compounds at R > 0.998. The bias and coefficients of variation of all the QC levels are within the range of 10% while the recovery in both charcoal-stripped and unstripped human serum is around 85%. The matrix effect was evaluated and the results well met the acceptance criteria according to the guidelines of bioanalytical method development and validation. Using this newly developed method, the concentrations of both androstane-3α,17β diol and androstane-3β,17β diol were measured in normal postmenopausal serum, where the concentrations range from 2 pg/mL to 32 pg/mL for androstane-3α,17β diol and from 1 pg/mL to 10 pg/mL for androstane-3β,17β diol, respectively.