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首页> 外文期刊>Journal of environmental monitoring: JEM >A proficiency testing scheme for aromatic hydrocarbons in air by the manual thermal desorption-GC method: a comparison of laboratory performance with the uncertainty requirements of the European Union Ambient Air Directive
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A proficiency testing scheme for aromatic hydrocarbons in air by the manual thermal desorption-GC method: a comparison of laboratory performance with the uncertainty requirements of the European Union Ambient Air Directive

机译：手动热脱附-GC方法对空气中芳烃的能力测试方案：实验室性能与欧盟环境空气指令的不确定性要求的比较

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The Workplace Analysis Scheme for Proficiency (WASP) is a proficiency testing scheme for the analysis of occupational hygiene and environmental air samples and is operated in the UK by the Health and Safety Laboratory. Since 1997, WASP has offered samples of benzene, toluene and m-xylene, at environmental levels on Tenax, and has about 35 laboratories participating, mostly from industry, local government and consultancy organisations in the UK. The results reported cover the first 10 rounds of the environmental analytes (1997-1999) and demonstrate the important role of proficiency testing in assessing the quality of laboratory performance. Estimates are obtained for within-laboratory precision and the total variability at each analyte level. The estimates of within-laboratory precision suggest that laboratories have more difficulty analysing toluene and m-xylene than benzene. Linear relationships for the reproducibility relative standard deviation (RSD_T) with loading level are evident for the analytes at occupational levels. At environmental levels, the relationship between loading level and reproducibility is much less well defined. The standard deviation for the proficiency testing assessment for all three analytes at the environmental level is 14%, as derived from the benzene data. Expanded uncertainty estimates (k = 1.96), for the analysis of samples since the scheme started, are obtained from the average total variance, and are 27% for benzene, 39% for toluene and 36% for m-xylene. Although the linear trend of performance against round number was not significant at the 95% level of confidence (p = 0.23 for benzene, p = 0.3 for toluene and p = 0.32 for m-xylene), there was a general improvement in RSD_T from 26-34% about 8-13% 10 rounds later. Currently, for a laboratory to meet one of the data quality objectives in the Ambient Air Directive (indicative measurement of benzene, expanded uncertainty ±30% or less), it would have to achieve a level of analytical performance to satisfy the category 1 (best performance) limit of better than ±8.8%. In the last proficiency testing round, discussed in this paper, only 58% of laboratories obtained performance scores that indicated that they were able to consistently achieve this level of performance.
机译：“工作场所熟练度分析计划（WASP）”是一项用于分析职业卫生和环境空气样本的能力测试计划，由英国健康与安全实验室负责运营。自1997年以来，WASP在Tenax上提供了环境水平的苯，甲苯和间二甲苯样品，并有大约35个实验室参加，其中大多数来自英国的工业，地方政府和咨询组织。报告的结果涵盖了前10轮环境分析物（1997-1999年），并证明了能力验证在评估实验室性能质量中的重要作用。获得实验室内精度和每个分析物水平的总变异性的估计值。实验室内精确度的估算表明，与苯相比，实验室在分析甲苯和间二甲苯方面难度更大。在职业水平上，分析物的重现性相对标准偏差（RSD_T）与负载水平之间存在线性关系。在环境水平上，负载水平与可再现性之间的关系定义得很少。从苯数据得出的所有三种分析物在环境水平下的能力验证评估的标准偏差为14％。自该方案开始以来，用于分析样品的扩展不确定性估计值（k = 1.96）是从平均总方差获得的，苯的平均值为27％，甲苯的比例为39％，间二甲苯的比例为36％。尽管在95％的置信度水平下，性能相对于整数的线性趋势并不显着（苯的p = 0.23，甲苯的p = 0.3，间二甲苯的p = 0.32），但RSD_T总体上从26提高了-10％后约8-13％发射-34％。当前，要使实验室达到《环境空气指令》中的数据质量目标之一（指示性苯的测量，不确定度扩大到±30％或更少），它必须达到一定的分析性能水平才能达到类别1（最佳）性能）限制优于±8.8％。在本文讨论的上一轮能力验证中，只有58％的实验室获得了绩效评分，表明他们能够始终如一地达到这一水平。

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