Fig. 3.

(A) Representative mass chromatograms of quantifier mass transitions for analyte, tamsulosin, 20 ng/mL (upper panel) and internal standard, d9-finasteride, 10 ng/mL (lower panel) from spiked extracted serum. (B) Representative mass chromatograms of tamsulosin (quantified as 17.1 ng/mL; upper panel) extracted from a patient sample enriched with internal standard, d9-finasteride (10 ng/mL; lower panel). The patient had received tamsulosin (0.4 mg daily) for 90 days. (C) To assess specificity, the method was applied to serum from patients not receiving tamsulosin (n = 3) with representative chromatograms shown (mass transition of tamsulosin (upper panel), d9-finasteride lower panel)). cps, counts per second.