A simple surrogate approach for the quantitation of C4 (7α-hydroxy-4-cholesten-3-one) in human serum via LC-MS/MS and its application in a clinical study.

We present a validated LC-MS/MS assay for the quantitation of 7α-hydroxy-4-cholesten-3-one (C4), a key intermediate in the bile acid synthesis pathway from cholesterol, in human serum. A surrogate matrix approach was employed to overcome the challenges posed by the endogenous C4 levels in the biological matrix. Human serum samples were spiked with stable isotope labeled internal standard (SIL-IS), processed using supported liquid extraction (SLE), and analyzed by LC-MS/MS.

Development and qualification of an LC-MS/MS method for quantification of MUC5AC and MUC5B mucins in spontaneous sputum.

Aim: Airway mucins in sputum are promising respiratory disease biomarkers, despite posing substantial analytical challenges due to their physicochemical properties and rare and heterogenous nature of the matrix. We aimed to identify a suitable sputum collection and processing method, and qualify a bioanalytical method for MUC5AC and MUC5B quantification in clinical samples.

Method: Mucins were quantified in induced and spontaneous sputum collected from the same COPD patients, following various sample processing procedures.