An original procedure was developed to simultaneously test β2-agonists (salbutamol and clenbuterol) and β-blockers (atenolol, acebutolol, pindolol, betaxolol, propranolol, timolol, sotalol, metoprolol, tertatolol, bisoprolol, labetalol and oxprenolol) in both human and animal hair. After decontamination with methylene chloride (2 times, 2 min), a 200 mg hair strand is pulverized in a ball mill. Then, a 100 mg portion is incubated overnight in 2 mL 0.1 N HCl, at 56°C, in the presence of carteolol, which was used as an internal standard. After neutralization of the acid phase with 0.1 N NaOH, a 2 mL bicarbonate buffer (pH 8.6) is added to the preparation, which is then purified by solid-phase extraction with Isolute C18 columns. Drugs are derivatized using a mixture of trimethylboroxine-ethyl acetate for 15 min at 80°C to form methaneboronate derivatives. Drugs are detected using GC/MS on an HP 6890-5973 system. A 4 µL portion of the derivatized extract is injected using a pulsed mode in a 30 m HP5 MS capillary column. Linearit was observed for all compounds in the range 25 pg/mg to 10 ng/mg. Limits of detection were in the range 2 to 10 pg/mg. At 1 ng/mg, recoveries were in the range from 37 to 100%, with a within-run precision of 5.9 to 14.1% (n = 8).
The application of the method can be documented by the following examples: (1) Hair from asthmatic patients (n = 11), including two cases of asthma deaths, tested positive for salbutamol in the range of 27 to 210 pg/mg, (2) A 24-year-old swimmer who tested positive in urine for salbutamol demed the results. Hair analysis confirmed salbutamol exposure, with a concentration of 71 pg/mg, (3) A shooting specialist was assumed to chronically use metoprolol (100 mg/daily, during some periods). Hair concentration of metoprolol was 8.41 ng/mg. (4) An archery specialist was assumed to chronically use sotalol (80 mg/daily, during some periods). Hair concentration of sotalol was 261 pg/mg. (5) Hair from two calves revealed chronic exposure to clenbuterol, which was used to increase the mass of the animals at a concentration of 30 and 48 pg/mg.