Determination of anabolic agents in dietary supplements by liquid chromatography-high-resolution mass spectrometry.

ABSTRACT

A sensitive method for the identification and quantification of anabolic steroids and clenbuterol at trace levels in dietary supplements by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) in atmospheric pressure ionisation (APCI) mode using a single-stage Orbitrap analyser operating at a resolution power of 100 000 full width at half maximum (FWHM) was developed and validated. A total of 1 g of dietary supplement was added with testosterone-d3 as internal standard, dissolved in methanol, evaporated to dryness, diluted in sodium hydroxide solution and extracted with a mixture of pentane/ethyl ether 91. The extract was directly injected into the LC-HRMS system. The method was fully validated. Limits of detection (LODs) obtained for anabolic androgenic steroids (AASs) varied from 1 to 25 ng g(-1) and the limit of quantitation (LOQ) was 50 ng g(-1) for all analytes. The calibration was linear for all compounds in the range from the LOQ to 2000 ng g(-1), with correlation coefficients always higher than 0.99. Accuracy (intended as %E) and repeatability (%CV) were always lower than 15%. Good values of matrix effect and recovery were achieved. The ease of the sample preparation together with a fast run time of only 16 min permitted rapid identification of the analytes. The method was applied to the analysis of 30 dietary supplements in order to check for the presence of anabolic agents not labelled as being present in these supplements. Many AASs were often detected in the same sample indeed, androstenedione was detected in nine supplements, 5-androsten-3ß-ol-17-one (DHEA) in 12, methandienone in three, stanozolol in one, testosterone in seven and testosterone esters in four of them. A retrospective analysis of suspected compounds not included at the beginning of the method development was also possible by means of the full acquisition spectra obtained with the HRMS technique.