LC-MS methods have been widely used to analyze vitamin D2 and vitamin D3 25-hydroxy metabolites (25OH D2 and 25OH D3) in human plasma. Clinical research laboratories are always seeking fast and cost-effective methods to improve analytical efficiency. Here we evaluated a high-efficiency, simple sample preparation method implemented on a Prelude SPLC system that combines online sample cleanup powered by Thermo Scientific TurboFlow technology with chromatographic separation and a TSQ Endura triple quadrupole mass spectrometer.

Plasma free metanephrine (MN) and normetanephrine (NMN), collectively known as Pmets, are important molecules for clinical research. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become widely used to measure Pmets because of its high analytical sensitivity and specificity. Because Pmets are very polar, special solid phase extraction (SPE) and chromatographic methods have been developed for their analysis. Ion-paring (IP)-SPE, which has been used to purify a wide range of polar compounds, is well suited for the purification of Pmets.

Clinical research laboratories perform analysis of methylmalonic acid (MMA) using LC-MS because of that technique’s sensitivity and selectivity. Usually, the quantitative method is developed on a triple quadrupole mass spectrometer. Here we evaluated a method implemented on a Q Exactive Focus ultra-high resolution quadrupole-Orbitrap mass spectrometer for the best selectivity.

Chromatographic separation is required for simultaneous analysis of 25-hydroxyvitamin D3 (25OHD3) and its epimeric form 3-epi-25-hydroxyvitamin D3 (epi-25OHD3) in a liquid chromatography-mass spectrometry (LC-MS) method because both compounds have the same molecular formulas and the same fragmentation spectra. We developed an LC method that provides baseline separation between the two isobaric compounds. We coupled this chromatographic method to an MS method, which collects high-resolution MS/MS spectra for compound identification and quantitation.

Analysis of testosterone in female and juvenile plasma samples for research requires an analytically sensitive method with a limit of quantitation of at least 10 pg/mL. Liquid chromatography coupled with mass spectrometry (LC/MS), an analytically sensitive and selective technique, is widely accepted for testosterone analysis in complex matrices such as human serum or plasma.