Analysis of Phthalate Esters in Lotion by Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplets Combined with Gas Chromatography

A novel dispersive liquid-liquid microextraction based on solidification of floating organic droplets(DLLME-SFO) combined with gas chromatography(GC) was developed,and validated in the pretreatment and determination of four phthalate esters(PAEs),including dibutyl phthalate,benzyl butyl phthalate,2-ethylhexyl phthalate,and di-n-octyl phthalate in lotion.The experimental conditions affecting extraction efficiencies for the analytes,such as extraction solvent volume,kind of dispersive solvent,dispersive solvent volume,extraction time,pH value and salt concentration were investigated.In the optimal DLLME-SFO method,the sample solution adjusted to pH 3.0 was prepared as a mixed solution of lotion-pure water(1 ∶ 10).15 μL 1-dodecanol(extraction solvent) and 1 300 μL ethanol(dispersive solvent) were rapidly injected into the sample solution.After vortexed for 1 min and centrifugated at 4 000 r· min-1 for 5 min,the sample was cooled down in an ice bath till 1-dodecanol became solid and formed a small ball.Then the solidified 1-dodecanol phase was transferred,and directly detected by GC method after it melted.As results,the linear ranges of the target PAEs were in the range of 5.0-500.0 μg· L-1.The detection limits ranged from 0.001 μg· L-1 to 1.0 μg· L-1.The recoveries were in the range of 88%-108%with relative standard deviations of 1.6%-3.3%.The enrichment factors for the target analytes ranged from 800 to 1 578.Compared with the other pretreatment methods for the extraction of PAEs,the developed method was simple,rapid,sensitive and accurate,and could be applied in the analysis of phthalate esters in lotion.