橄榄油中卤化溶剂的残留量是衡量其质量的重要指标。《国家橄榄油质量标准》GB/T23347-2021规定,橄榄油中各卤化溶剂的残留量应≤0.1mg/kg,卤化溶剂的总残留量应≤0.2mg/kg。COI/T.20/Doc.不。8-1990,由国际橄榄理事会出版,描述了用于测定橄榄油中卤化溶剂的标准方法。不幸的是,这种方法很麻烦,重复性差,自动化程度低,不适合检测和分析大量橄榄油中残留的卤化溶剂。目前,我国尚无橄榄油中卤化溶剂残留量的国家标准测定方法。因此,开发简单,高效,准确,橄榄油中卤化溶剂残留量的稳定测定方法势在必行。在本文中,建立了一种基于自动顶空气相色谱法测定卤化溶剂残留量的方法,即,氯仿,四氯化碳,1,1,1-三氯乙烷,二溴氯甲烷,四氯乙烯,和溴仿,橄榄油。如下处理样品。混合后,将2.00g(精确至0.01g)的橄榄油样品添加到20mL顶部空间注射瓶中,并立即密封用于顶部空间气相色谱分析。空白初榨橄榄油用于制备标准工作溶液和用于定量的外标方法。研究了用于制备卤化溶剂标准中间体的溶剂,并选择甲醇代替N,N-二甲基乙酰胺制备卤化溶剂标准中间体由于其安全性。不同注射时间(1、2、3、4、5、6s)的影响,平衡温度(60,70,80,90,100,110,120℃),研究了顶空采样器在检测六种卤化溶剂残留量时的平衡时间(4、5、8、10、20、30、40分钟)。最佳注射时间和平衡温度为3s和90℃,分别。当平衡时间为30分钟时,该方法对六种卤化溶剂表现出良好的分析性能。对优化后的方法进行了方法学研究,结果表明,6种卤化溶剂在0.002~0.200mg/kg范围内呈良好的线性关系,相关系数≥0.9991。1,1-三氯乙烷和溴仿的检出限(LODs)和定量限(LOQs)分别为0.0006和0.002mg/kg,分别。氯仿的LOD和LOQ,四氯化碳,二溴氯甲烷,四氯乙烯分别为0.0003和0.001mg/kg,分别。不同加标水平下的平均回收率为85.53%-115.93%,相对标准偏差(n=6)为1.11%~8.48%。建立的方法用于分析市场上13个橄榄油样品。尽管在这些样品中没有检测到卤化溶剂,有限数量的样品并不代表所有的橄榄油。因此,监测橄榄油中残留的卤化溶剂对于其安全消费仍然是必要的。该方法对六种卤化溶剂的LOQs明显低于COI/T.20/Doc。不。8-1990标准方法(0.02mg/kg)。此外,该方法操作时间短,操作精度高,自动化程度高,准确度好。因此,该方法适用于大批量橄榄油样品中6种卤代溶剂残留量的测定和分析。
The residual amount of halogenated solvents in olive oil is an important indicator of its quality. The National Olive Oil Quality Standard GB/T 23347-2021 states that the residual amount of individual halogenated solvents in olive oil should be ≤0.1 mg/kg and that the total residual amount of halogenated solvents should be ≤0.2 mg/kg. COI/T.20/Doc. No. 8-1990, which was published by the International Olive Council, describes the standard method used for the determination of halogenated solvents in olive oil. Unfortunately, this method is cumbersome, has poor repeatability and low automation, and is unsuitable for the detection and analysis of residual halogenated solvents in large quantities of olive oil. At present, no national standard method for determining residual halogenated solvents in olive oil is available in China. Thus, developing simple, efficient, accurate, and stable methods for the determination of residual halogenated solvents in olive oil is imperative. In this paper, a method based on automatic headspace gas chromatography was established for the determination of residual halogenated solvents, namely, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, dibromochloromethane, tetrachloroethylene, and bromoform, in olive oil. The samples were processed as follows. After mixing, 2.00 g (accurate to 0.01 g) of the olive oil sample was added into a 20 mL headspace injection bottle and immediately sealed for headspace gas chromatography analysis. Blank virgin olive oil was used to prepare a standard working solution and the external standard method for quantification. The solvents used in the preparation of halogenated solvent standard intermediates were investigated and methanol was selected as a replacement for N,N-dimethylacetamide to prepare a halogenated solvent standard intermediate owing to its safety. The effects of different injection times (1, 2, 3, 4, 5, 6 s), equilibration temperatures (60, 70, 80, 90, 100, 110, 120 ℃), and equilibration times (4, 5, 8, 10, 20, 30, 40 min) of the headspace sampler on the detection of the residual amounts of the six halogenated solvents were investigated. The optimal injection time and equilibration temperature were 3 s and 90 ℃, respectively. The method demonstrated good analytical performance for the six halogenated solvents when the equilibration time was 30 min. A methodological study was conducted on the optimized method, and the results showed that the six halogenated solvents exhibited good linear relationships in the range of 0.002-0.200 mg/kg, with correlation coefficients of ≥0.9991. The limits of detection (LODs) and quantification (LOQs) of 1,1,1-trichloroethane and bromoform were 0.0006 and 0.002 mg/kg, respectively. The LODs and LOQs of chloroform, carbon tetrachloride, dibromochloromethane, and tetrachloroethylene were 0.0003 and 0.001 mg/kg, respectively. The average recoveries under different spiked levels were 85.53%-115.93%, and the relative standard deviations (n=6) were 1.11%-8.48%. The established method was used to analyze 13 olive oil samples available in the market. Although no halogenated solvents were detected in these samples, a limited number of samples does not represent all olive oils. Hence, monitoring residual halogenated solvents in olive oil remains necessary for its safe consumption. The LOQs of the method for the six halogenated solvents were significantly lower than that of the COI/T.20/Doc. No. 8-1990 standard method (0.02 mg/kg). In addition, the developed method can be conducted under short operation times with high precision and degree of automation as well as good accuracy. Thus, the proposed method is suitable for the determination and analysis of the residues of the six halogenated solvents in large batches of olive oil samples.