[Determination of yohimbine in serum by high performance liquid chromatography].

An automated method for determination of yohimbine (Yoh) in the serum was developed by means of column switching high performance liquid chromatography (HPLC). TSK-precolumn BSA-ODS and TSK-gel ODS-120T were used as a precolumn and analytical column, respectively. The wavelengths of detection were used at 280 nm (excitation) and 360 nm (emission). A 100 microliter serum sample is directly injected onto the precolumn. Yoh is then eluted within 30 min with an methanol-potassium phosphate buffer mixture. The analytical recoveries (99.3-110.4%), reproducibilities (within-run, C.V. less than 2.27%), and detection limit (0.80 ng/ml, S/N = 3) indicate that this system is suited for determination of Yoh. The five healthy volunteers received a single oral dose 10 mg of HYoh powder. The average of the maximal serum concentration and the area under the curve (AUC) from 0 to 4 h were 10.3 +/- 0.88 ng/ml and 19.70 +/- 0.87 ng.h.ml-1, respectively. The elimination rate constant (Kc1) was 0.52 +/- 0.03 h, and biological half-life (t1/2el) was 1.32 +/- 0.12 h.