| Cosmetics are closely related to human daily life.In recent years,cosmetics are often found to contain prohibited substances specified by the state and harm people's health.Therefore,it is necessary to strengthen the detection of cosmetics.The key for the detection is to determine the prohibited substances contained in cosmetics quickly and accurately.However,due to the complexities of cosmetic components and the low contents of banned components,it is often indispensable to separate and enrich the components before determination.On-line separation and enrichment have been one of the development trends of sample pretreatment technologies,due to the automated sample preprocessing with its own advantages,which are fast processing speed,less loss,large flux.Sample pretreatment mainly includes liquid phase extraction,solid phase extraction and so on.As "green"solvents,imidazolium ionic liquids have attracted wide attention because of their low volatilities,wide ranges of liquid path,high recycling and strong designabilities.In this paper,a series of imidazole ionic liquids were prepared and applied to the analysis of banned components in cosmetics by using self-made on-line separation and enrichment device.The contents include the following parts:1.An on-line extraction tube was developed to form an aqueous two-phase extraction system by using hydrophilic room temperature ionic liquid(1-tetraalkyl-3-methylammonium bromide)and anionic surfactant(sodium dodecyl sulfate)combined with a trace flow cuvette.Rhodamine B was extracted into the ionic liquid phase to achieve the separation.The effects of surfactant concentration,ionic liquid concentration,equilibrium time and temperature of extraction were studied.Under optimized conditions,the method linear range was 0.04-0.55?g/mL,the detection limit was 2.8 ng/mL.The method was easy to operate,and the using of online technology reduced the manual manipulation in the experiment.The method was applied to the determination of Rhodamine B in several cosmetics with satisfactory results.2.A new method for on-line extraction of Cd2+with ionic liquid aqueous two-phase system(1-butyl-3-methylimidazolium bromide/sugar)combine with flame atomic absorption spectrometry was established by using a self-made on-line separation device.Experiment conditions such as pH,the amount of ionic liquid and sucrose,equilibrium time were optimized.Under optimized conditions,the linear range was 0.5-20.00 ng/mL,and the detection limit(3?)was 0.14 ng/mL.The method was applied to the determination of Cd2+in several cosmetics with satisfactory results.3.A simple and rapid method based on ionic liquid liquid-liquid microextraction with 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF6])coupled with electrothermal atomic absorption spectrometry(GFAAS)was developed for the online speciation of arsenite(As(V))/arsenate(As(?))in cosmetic samples.With this method,As(V)could be extracted by[BMIM][PF6]at pH 6.5 due to the formation of a hydrophobic complex,whereas As(?)remained in the aqueous solution.Various factors including pH,volume of[BMIM][PF6],equilibrium temperature and time,effect of salt were investigated by single factor experiment design and orthogonal experimental design.Under the optimized conditions,the limits of detection(3a)was 0.04 ng/mL,and its relative standard deviations was 3.5%(n=9,c=20.00 ng/mL).The proposed procedure was applied without any chelating or dispersive agent.The method was validated against the certified reference materials(GBW08666),and successfully applied to determine As(?)and As(?)in real cosmetic samples.4.A new method for the determination of RhB by on-line solid-phase extraction-ultraviolet spectrophotometry with a special self-designed device was established.1-hexadecyl-3-cyclodextrin-based imidazolium hexafluorophosphate was filled in phase extraction microcolumn to realize RhB extraction.The extraction parameters and elution parameters were optimized.Under optimized conditions,the linear range was 0.08-8.7?g/mL,the linear correlation coefficient is 0.9991,the detection limit(s/n=3)was 4.7 ng/mL,the adsorption capacity was 9.5 mg/g.The extraction mechanism was studied and it was found that the extraction was mainly due to the hydrogen bonding.This method was successfully applied to the separation and analysis of RhB in cosmetics.5.A special self-designed device based on poly-1-vinyl-3-pentylimidazole hexaflfluorophosphate(PILs-Cs)solid-phase extraction and high performance liquid chromatography(HPLC)was proposed as a novel method for the on-line separation and analysis of RhB dye.Single factor experiment design and orthogonal experiment design were used to optimize the experimental parameters,such as pH,the amount of PILs-Cs,sample volume,flflow rate,eluent type,eluent concentration,eluent volume,and the flow rate of eluent.Under the optimized conditions,the linear range was 0.02-2.4 mg/mL,with the correlation coefficients(R)of 0.9993.The limit of detection(LOD)and limit of quantifification(LOQ)were 4.0 ng/mL and 20.0 ng/mL,respectively.The extraction capacity was 6.22 mg/g,and enrichment ratio was 15.The extraction mechanism and the post-treatment method of PILs-C5 were also studied.This method was applied to analyze RhB in a wide variety of real samples with satisfactory results. |
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