气流吹扫-注射器微萃取-全二维气相色谱法用于原油组分的表征

建立了气流吹扫-注射器微萃取（GP-MSE）与全二维气相色谱/飞行时间质谱（GC×GC/TOFMS）联用分析原油成分的方法。为了找到适用于原油样品分析的GP-MSE条件，用饱和烃混合标准溶液和15种芳烃的混合标准溶液进行了条件优化，得到的最佳条件如下:取样量5 mg、萃取溶剂正己烷20 μ L、载气流速2 mL/min、加热时间3 min、加热温度300 ℃、冷凝温度-2 ℃。处理后的样品在全二维色谱/飞行时间质谱上进样分析，得到了满意结果。方法的检出限为34~93 μg/L，线性相关系数（R²）>0.99，对50种烃类化合物的回收率在82.0%~107.3%之间，相对标准偏差<10%（n=5）。结果表明GP-MSE-GC×GC/TOFMS法是一种新型绿色、高效、灵敏的分析方法，非常适合原油中挥发性与半挥发性组分的分析。

Characterization of compounds in crude oils by gas purge micro-syringe extraction coupled to comprehensive two-dimensional gas chromatography

A novel sample pretreatment method, gas purge micro-syringe extraction (GP-MSE), coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOFMS) has been developed for the characterization of volatile and semi-volatile compounds in crude oils. In the sample pretreatment process, the analytes were carried to the microsyringe barrel by inert gas, and at the same time, trapped by an organic solvent. The whole process of extraction takes less than 10 min, and only 20 μ L of organic solvent was needed. Using two custom standard solutions containing alkanes and polycyclic aromatic hydrocarbons (PAHs), the influences of the extraction conditions were investigated. The optimized conditions were as follows: 5 mg crude oil, 20 μ L hexane (extraction solvent), extraction for 3 min at 300 ℃, condensation temperature set at -2 ℃, gas flow rate set at 2 mL/min. Under the optimized conditions, a real crude oil sample was extracted and then analyzed in detail. It showed that the proposed method was very effective in simultaneously analyzing the normal and branched alkanes, cycloalkanes, aromatic hydrocarbons, and biomarkers of crude oil such as steranes and terpanes. The recoveries obtained ranged from 82.0% to 107.3% and the detection limits ranged from 34 to 93 μg/L. The correlation coefficients (R²) were more than 0.99. The relative standard deviations (RSDs, n=5) for all the analytes were below 10%. The results indicate that the proposed method is suitable for the characterization of volatile and semi-volatile compounds in crude oils with easy operation, high sensitivity and efficiency.