Rapid determination of 18 glucocorticoids in serum using reusable on-line SPE polymeric monolithic column coupled with LC-quadrupole/orbitrap high-resolution mass spectrometer

A simple, rapid and sensitive method for the simultaneous determination of 18 glucocorticoids in serum was developed by coupling on-line solid-phase extraction (SPE) polymeric monolithic column to a liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometer. A simple poly(ethylene glycol dimethacrylate) monolith column (10 mm x 2.1 mm i.d.) was fabricated, and the morphology, surface area and extraction performance of the monolithic column were characterized. Serum samples were extracted by acetonitrile (ACN). Then, online SPE was achieved on the synthesized monolithic column using a 10 mmol/L ammonium acetate solution as the loading solvent. After the transfer from the monolith into analytical column (Capcell Pak ADME column) using ACN, the adsorbed analytes were separated on the analytical column and detected with a high resolution hybrid quadrupole/orbitrap mass spectrometer with full scan/ddMS(2) scan mode Under optimized conditions, the method was linear with target linear correlation coefficient (R-2) higher than 0.995. Detection limits were in range of 0.1-0.6 ng/mL, and the quantification limits were 0.3-1.5 ng/mL. The recovery was between 71.9% and 89.2% in three spike levels with precision (n = 5) of 5.40-12.1%. The serum sample was directly analyzed after a simple extraction procedure, and the on-line SPE and determination were achieved within only 16 min. The method was used to analyze the dynamic contents variation of cortisone and hydrocortisone in serum before and after the surgery.