RESUMO
A readily applicable method was developed to determine the concentration level of zaltoprofen, a non-steroidal antiinflammatory drug from the propionic acid family, in human plasma. This method is based on manual-shaking-assisted dispersive liquid-liquid microextraction coupled with liquid chromatography with ultraviolet detection. Factors affecting the extraction efficiency were screened and optimized by experimental design using fractional factorial and central composite designs, respectively. Optimal conditions were: 220 µL of C2 H4 Cl2 (extraction solvent), 5 mL of 3.75% w/v NaCl aqueous solution at pH 2.0, and manual shaking for 13 s (65 times). The resulting extraction method yielded a reasonable enrichment factor of 18.0 (±0.6, n = 3) and extraction recovery of 86.0% (±3.3%, n = 3). The established method was validated for selectivity, linearity, precision, accuracy, matrix effect, recovery, dilution integrity, and stability, and it met the acceptable criteria for all of the tested parameters. Specifically, the method was linear in the range of 0.16-50.0 mg/L, precise (< 8.8% RSD), accurate (-7.5-5.6% deviation), and showed negligible matrix effects (96.1-106.4%) with high absolute recovery (94.5-97.7%). Compared with previous methods involving labor-intensive liquid-liquid extraction or non-specific protein precipitation, our method allows the simple, rapid, and efficient determination of zaltoprofen using the most affordable analytical instrument, liquid chromatography with ultraviolet detection.