On-line liquid chromatography-comprehensive two dimensional gas chromatography with dual detection for the analysis of mineral oil and synthetic hydrocarbons in cosmetic lip care products

Highlights: • On-line LC-GC×GC-MS/FID method for the characterization of MOH contamination. • Dual detection provides both qualitative and quantitative data in a single run. • The method was characterized by satisfactory figures of merit, for MOSH and MOAH. -- Abstract: An on-line liquid chromatography-comprehensive two-dimensional gas chromatography (LC-GC×GC) separation process, combined with a dual detection system, namely triple quadrupole mass spectrometry (used as a single quadrupole - QMS) and flame ionization detection (FID), was developed for the analysis of cosmetic lip care products. The LC step was carried out by using a fused-core silica column, with this enabling the separation of mineral oil saturated hydrocarbons (MOSH), as well as polyolefin oligomeric saturated hydrocarbons (POSH), from the mineral oil aromatic hydrocarbon (MOAH) families. Each chemical class was then subjected to GC×GC-QMS/FID analysis, using a medium polarity-low polarity column combination. Notwithstanding the utility of the flame ionization detector for quantification purposes, it is obviously also desirable to obtain information on the type of hydrocarbons present (of mineral or synthetic origin), in order to identify a potential contamination source. Following method optimization, various analytical figures of merit (method linearity, intra- and inter-day repeatability, limits of detection and quantification, and injector discrimination) were measured. Specifically, for MOSH and MOAH, linearities were evaluated in the 32.5–2080 and 50–500 mg L⁻¹ range, respectively; furthermore, intra- and inter-day repeatability values were 6.2 and 8.3%, respectively, while limits of detection and quantification were 3.5 and 11.8 mg L⁻¹, respectively. The proposed method, enables for the first time (to the best of the authors' knowledge), the detailed qualitative and quantitative analysis of saturated and aromatic hydrocarbons, in a single run and in a fully-automated manner. Quantities of MOSH + POSH in the cosmetic products ranged from 8.7 to 44.4% (CV values were in the 1.5–5.4% range) while MOAH contamination was found in four samples, ranging from 386 to 5869 mg kg⁻¹ (CV values were in the 0.5–4.5% range).