Simultaneous determination of four fluorescent whitening agents (including trans and cis isomers) in facial mask by dispersive solid‐phase extraction combined with ultra high performance liquid chromatography and diode array detection

A novel ultra high performance liquid chromatography with diode array detection method, based on the dispersive solid‐phase extraction by using polymer weak anion exchange as the sorbent, was established for the simultaneous determination of fluorescent whitening agents 85, 28, 351, and 71 in facial mask. The amounts of polymer weak anion exchange, adsorption time, and volume of elution solvent in the dispersive solid‐phase extraction technology were optimized, and the developed method was validated in terms of the method limit of detection, method limit of quantitation, linear range, recovery, accuracy, and precision. Results indicated that the standard curves were linear over the selected concentration ranges of 0.05–100 mg/L for four target analytes, with determination coefficients greater than 0.999. The method limits of quantitation of the target analytes were in the range of 0.6–2.8 mg/kg. Recoveries were calculated at the concentrations of 1.0–30 mg/kg spiked in negative samples and the values were between 89.3 and 102% with an RSD of 2.5–5.1% for intraday precision and 3.8–5.0% for interday precision. The method was successfully applied to analyze 20 facial mask samples and fluorescent whitening agent 85 was detected in one sample with the concentration of 4.7 mg/kg.