Speciation of mercury in liquid cosmetic samples by ionic liquid based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-inductively coupled plasma mass spectrometry

Ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for the determination of mercury species in liquid cosmetic samples is described. Firstly mercury (Hg(2+)), methylmercury (MeHg(+)) and ethylmercury (EtHg(+)) were complexed with ammonium pyrrolidinedithiocarbamate (APDC), and then the complexes were extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) using DLLME. Under the optimized conditions, the enrichment factors of 760, 115, 235 for Hg(2+), MeHg(+) and EtHg(+) were obtained from only 5.00 mL sample solution. The detection limits of the analytes (as Hg) were 1.3 ng L(-1) for Hg(2+), 7.2 ng L(-1) for MeHg(+) and 5.4 ng L(-1) for EtHg(+), respectively. The relative standard deviation (n = 10) of 0.5 ng mL(-1) Hg(2+), MeHg(+) and EtHg(+) were 7.4%, 5.2% and 2.3%, respectively. Finally, the developed method was successfully applied for the speciation of mercury in four liquid cosmetic samples, Hg2+ was found as the main species in these samples, and a spike test was performed to verify the accuracy of the method.