Abstract:

A high throughput screening method based on ultra performance liquid chromatography-quadrupole-time-of-flight high resolution mass spectrometry (UPLC-Q-TOF HRMS) was developed for the simultaneous and rapid confirmation of 73 prohibited compounds in cosmetics. The sample was dispersed in a saturated sodium chloride solution and ultrasonically extracted using acetonitrile containing 0.2% (v/v) formic acid. The resultant solution was centrifuged and then cleaned using dispersive solid phase extraction using a primary secondary amine (PSA) sorbent. The purified solution was centrifuged, and the supernatant was filtered through a 0.22 μm membrane before determination. The optimal pretreatment method was determined by comparing the recovery rates obtained using different extraction solvents and different amounts of purifying agents. The chromatographic separation conditions and mass spectrometry scanning mode were also optimized. Chromatographic separation was performed on an Acquity UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) with gradient elution using 0.1% (v/v) formic acid aqueous solution and methanol as mobile phases. The eluent from the column was further detected using Q-TOF HRMS with the high resolution multiple reaction monitoring (MRM HR) scanning mode. Retention time, precise mass of parent ion, isotope abundance ratio, and precise mass of fragment ions were the parameters considered for rapid untargeted screening and confirmation. The matrix effects of water- and cream-based cosmetics were investigated. The matrix effects could be addressed using the matrix matched standard curve method. The correlation coefficients for the 73 prohibited compounds were all >0.99 in the corresponding linear concentration range. The limits of detection (LODs) were in the range of 5-150 μg/kg, and the limits of quantification (LOQs) were in the range of 15-450 μg/kg. Average recoveries were in the range of 60.3%-130.3% at three spiked levels, and the intra-day and inter-day precisions were 0.8%-10.0% (n=6) and 1.1%-15.0% (n=3), respectively. A total of 692 cosmetics samples were screened; 16 positive samples were detected, namely, sulfamethoxazole, meprednisone, lincomycin, 4-acetamidophenol, trimethoprim, alfacalcidol, betamethasone 17-valerate, brimonidine, chloramphenicol, chlorpheniramine, clobetasol propionate, crotamiton, econazole, ketoconazole, prednisone 21-acetate, and prednisone, with content in the range of 0.5-1136.1 mg/kg. The optimized method is accurate, fast, and simple, and it is suitable for the routine detection and rapid screening of common prohibited compounds in cosmetics. In addition, a screening and confirmation library was established for the 650 prohibited compounds using SCIEX OS and Library View software, using information-dependent acquisition (IDA)-MS/MS mode for MS data acquisition. The database contains multiple types of information, including formulas, theoretical exact mass, retention time, precise mass of parent ion, isotope abundance ratio, and fragment ion distribution. The library can be used for the simultaneous and rapid confirmation of prohibited compounds in cosmetics.

Key words: ultra performance liquid chromatography (UPLC), quadrupole-time-of-flight high resolution mass spectrometry (Q-TOF HRMS), prohibited compounds, cosmetics