Comprehensive screening of 63 coloring agents in cosmetics using matrix solid-phase dispersion and ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry

An analytical methodology for comprehensive screening of 63 coloring agents of great concern for regulatory control in cosmetics has been established using ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS). An effective, rapid, and simple sample pretreatment protocol with low sample and reagent consumption was developed based on matrix solid-phase dispersion (MSPD). The selection of the most suitable extraction conditions was made using statistical tools of factorial multifactor experimental design and analysis of variance (ANOVA). In the final conditions, 0.1 g of cosmetic sample was blended with 0.3 g of anhydrous sodium sulfate and 0.4 g of sand, and the MSPD column was eluted with 2 mL of methanol. The extract was analyzed by UHPLC-Q-Orbitrap HRMS under synchronous full-scan MS and data-dependent MS/MS (full-scan MS¹/dd-MS²) acquisition mode. The mass resolution was set to 70,000 FWHM (full width at half maximum) for full-scan MS¹ and 17,500 FWHM for dd-MS² stage with the experimentally measured mass deviations of less than 3 ppm (parts per million) for quasi-molecular ions and 5 ppm for characteristic fragment ions for each individual analyte. An accurate-mass database and a mass spectral library were built in house for searching the 63 target compounds. Broad screening was conducted by comparing the experimentally measured exact mass of precursor and fragment ions, retention time, isotopic pattern, and ionic ratio with the accurate-mass database and by matching the acquired MS/MS spectra against the mass spectral library. Method performance was evaluated in terms of limits of detection (LODs), limits of quantitation (LOQs), linearity, precision, recovery, and matrix effect. The UHPLC-Q-Orbitrap HRMS approach was applied for the simultaneous analysis of 63 target coloring agents in 69 genuine cosmetic samples. Eleven legally prohibited coloring agents were detected in 26 cosmetic samples in total. The proposed method exhibited great potential for high-throughput, sensitive, and reliable screening of multi-class coloring agent substances in cosmetics.