Gas chromatograph–mass spectrometric method for the determination of carvedilol and its metabolites in human urine

A sensitive and efficient method was developed for the determination of carvedilol and its metabolites in human urine by gas chromatography–mass spectrometry (GC–MS). Urine samples were hydrolyzed with β-glucuronidase/arylsulfatase (from Helix pomatia) and the target compounds were extracted with liquid–liquid extraction. The extracts were completely derivatized with MSTFA and MBTFA and analyzed by GC–MS using an Ultra-2 column. The linearity of the assay ranges were 0.75–75 ng mL−1 for carvedilol and o-desmethyl carvedilol (o-DMC), and 3.0–75 ng mL−1 for 4-hydroxyphenyl carvedilol (4-HPC) and 5-hydroxyphenyl carvedilol (5-HPC). The absolute recovery of carvedilol and its metabolites added to a blank urine sample was 80.1–97.8%. The limits of detection (LOD) and quantitation (LOQ) of carvedilol and o-DMC were 0.30 and 0.75 ng mL−1, and its of 4-HPC and 5-HPC were 0.75 and 3.0 ng mL−1, respectively. The reproducibilities were 1.86–11.5% for the intra-day assay, and 0.70–1.71% for the inter-day assay precision and the degree of inaccuracy was −3.0 to 3.9% at the concentration of 75 ng mL−1. The proposed GC–MS method was effective for the determination of carvedilol and its three metabolites in human urine.