组合蒸馏技术用于气相色谱分析的样品前处理

A Multi-Step Distillation Method for Sample Preparation in Gas Chromatographic Analysis

研究了一种组合蒸馏方法的样品前处理技术,并将其研制成样品预处理装置,运用载体、携带体和组合蒸馏技术实现待测样品中微量成分的提取、分离和富集。将分子蒸馏收集端的冷端接收器设计为可更换结构,避免了样品的交叉污染问题。在乙酸乙酯中添加4种有机磷农残标样作为评价样品,所研制的装置能自动将农残组分富集到2mL邻苯二甲酸二甲酯中。利用气相色谱分析的结果,对该样品前处理装置的分离富集参数进行了优化。实验结果表明,该方法能完全除去蛋白、脂肪、色素等对气相色谱分析有干扰的组分;能将待测微量组分的浓度富集150倍以上;回收率为90%～117%,相对标准偏差为1.3%～10%;最小检出浓度为1ng/mL;可以处理高于100g的样品量;可以得到几十毫克至上百毫克的目标组分;有机试剂的回收利用率大于95%;操作简单方便。用模拟样品做了实际应用实验。该技术适合沸程为120～600℃组分的富集。所研制的装置适用于大量样品中痕量组分的半制备级富集。

A sample pretreatment device based on multi-step distillation principle was constructed and evaluated. Trace components in the sample were extracted, separated and enriched at the cold receptor of the molecular diffusion distillation device. The cold receptor was designed as an exchangeable part to avoid the cross interferences from one sample to another one. A model sample containing four kinds of organophosphorus pesticides in ethyl actate was tested in the device, and the distillated and enriched solution was analyzed by a gas chromatograph. It was proven that the interferential components to gas chromatography such as protein, lipid and pigment could be removed effectively, and the enrichment factor for trace target components was more than 150 times. The recoveries of the method were from 90% to 117%, and the relative standard deviations （RSDs） from 1.3% to 10%. The limit of detection （LOD） of this method was 1 ng/mL without further concentration. The reused ratio of the organic reagents was more than 95%. Practical application was performed by using a spiked tea sample. The device can treat more than 100 g of samples with a boiling point range of 120 -600 ℃.