| Abstract |
This study proposes a new analytical methodology for the determination of trace levels of testosterone (T) and epitestosterone (E) in urine matrices using bar adsorptive microextraction combined with liquid desorption followed by high-performance liquid chromatography with diode array detection (BA mu E-LD/HPLC-DAD). The comparison of different sorbent coatings (five activated carbons, one styrene-divinylbenzene, two modified pyrrolidone, one ciano and one n-vinylpyrrolidone polymers) through BA mu E showed that the latter phase presented much higher selectivity and capacity offering multiple mechanisms of interaction. Assays using this phase were performed on 25 mL of water samples spiked at the 8.0 mu g/L level, yielded average recoveries of 92.1 and 93.4\% for T and E, respectively, under optimized experimental conditions; BA mu E (n-vinylpyrrolidone): 16 h (1000 rpm), pH 5.5; LD: acetonitrile, 30 min under sonication treatment. From the developed analytical methodology, suitable detection limits were achieved (0.4 mu g/L) and good linear dynamic ranges (1.4-16.0 mu g/L) with remarkable determination coefficients (r(2) > 0.9978). By using the standard addition methodology, the application of the present analytical approach on urine samples revealed good sensitivity. The proposed method; which operated under the floating sampling technology, proved to be a suitable sorption-based static microextraction alternative for screening T, E and the T/E ratio in urine samples for doping control purposes. The methodology showed to be easy to implement, demonstrating good reproducibility, sensitivity and robustness, allowing the possibility to choose the most selective sorbent coating according to the compounds of interest. (C) 2014 Elsevier B.V. All rights reserved. |
