Lopez-Avila V, Young R, Kim R, Beckert W F
Midwest Research Institute, California Operations, Mountain View 94043.
J AOAC Int. 1993 May-Jun;76(3):555-614.
A collaborative study was conducted, with 14 laboratories participating, to determine the method accuracy and precision of the proposed U.S. Environmental Protection Agency Methods 3560 and 8440. These methods involve the extraction of petroleum hydrocarbons from solid matrixes with supercritical carbon dioxide at 340 atm and 80 degrees C for 30 min (dynamic), collection of the extracted materials in tetrachloroethene (Method 3560), and analysis of the extracts by infrared (IR) spectrometry (Method 8440). The study design was based on the AOAC blind replicate design with balanced replicates. The study samples consisted of 4 solid matrixes that had petroleum hydrocarbon contents ranging from 614 to 32,600 mg/kg. Each of the 4 matrixes was extracted in triplicate, and the extracts were analyzed with 2 different IR spectrometers. In addition, each of the participating laboratories extracted a sample of unspiked clay soil, the same clay soil spiked with corn oil and reference oil at 1000 mg/kg each, and the same clay soil wetted to 30% water content and spiked with motor oil at 10,000 mg/kg (the latter 3 samples were extracted only once). Results indicated that the overall method accuracy for concentrations ranging from 614 to 32,600 mg/kg was 82.9%; the mean recoveries of petroleum hydrocarbons for each of the 4 solid matrixes ranged from 77.9 to 107% for analyses performed with the Perkin-Elmer Fourier transform IR spectrometer and from 75.9 to 101% for analyses performed with the Buck-Scientific IR spectrometer; the differences between the 2 instruments on a sample-by-sample basis were less than 17% for the total petroleum hydrocarbon determinations. The interlaboratory method precisions (RSDR) appeared to be matrix-dependent and ranged from 17.3 to 45.4% for analyses performed with the Perkin-Elmer Fourier transform IR spectrometer and from 16.7 to 47.9% for the Buck-Scientific IR spectrometer. The intralaboratory method precisions (RSDr) appeared to be less matrix-dependent and ranged from 11.5 to 17.0% for analyses performed with the Perkin-Elmer FTIR spectrometer and from 11.1 to 18.2% for the Buck-Scientific IR spectrometer. Method accuracy and precision data are also presented for the 5 laboratories that used Isco supercritical fluid extraction systems and for the 7 laboratories that used vessels with volumes of 3.5 mL or less with different supercritical fluid extraction systems.
开展了一项合作研究，有14个实验室参与，以确定美国环境保护局方法3560和8440的方法准确度和精密度。这些方法包括在340个大气压和80摄氏度下用超临界二氧化碳从固体基质中提取石油烃30分钟（动态），在四氯乙烯中收集提取的物质（方法3560），以及通过红外（IR）光谱法分析提取物（方法8440）。研究设计基于AOAC盲法重复设计且重复次数均衡。研究样品由4种固体基质组成，其石油烃含量在614至32,600毫克/千克之间。4种基质中的每一种都进行了三次提取，提取物用2种不同的红外光谱仪进行分析。此外，每个参与实验室都提取了未加标粘土土壤的样品、分别添加了1000毫克/千克玉米油和参比油的相同粘土土壤样品，以及含水量为30%并添加了10,000毫克/千克机油的相同粘土土壤样品（后3个样品仅提取一次）。结果表明，浓度范围为614至32,600毫克/千克时的总体方法准确度为82.9%；用珀金埃尔默傅里叶变换红外光谱仪进行分析时，4种固体基质中每种基质的石油烃平均回收率在77.9%至107%之间，用巴克科学红外光谱仪进行分析时，平均回收率在75.9%至101%之间；在逐个样品的基础上，两种仪器在总石油烃测定方面的差异小于17%。实验室间方法精密度（RSDR）似乎取决于基质，用珀金埃尔默傅里叶变换红外光谱仪进行分析时，其范围为17.3%至45.4%，用巴克科学红外光谱仪进行分析时，其范围为16.7%至47.9%。实验室内方法精密度（RSDr）似乎对基质的依赖性较小，用珀金埃尔默傅里叶变换红外光谱仪进行分析时，其范围为11.5%至17.0%，用巴克科学红外光谱仪进行分析时，其范围为11.1%至18.2%。还给出了使用Isco超临界流体萃取系统的5个实验室以及使用体积为3.5毫升或更小的容器和不同超临界流体萃取系统的7个实验室的方法准确度和精密度数据。
