新标准方法实施后水中石油类检测实验室能力验证结果比对研究

为推进国际履约进程,我国自2019年1月1日起停止实验室用途使用四氯化碳,原针对水中石油类的分析方法《水质石油类和动植物油类的测定红外分光光度法》(HJ 637—2012)随之失效,新分析方法则在2018年10月正式发布。随着新分析方法的发布实施,有必要考察实验室采用新方法分析水中石油类的能力。通过汇总两次能力验证计划的统计结果,分析了实验室采用两种新方法分析水中石油类的能力。结果显示:采用紫外分光光度法(HJ 970—2018)和红外分光光度法(HJ 637—2018)测定水中石油类能力验证参加实验室的满意率分别为79.1%和86.6%,分别低于和高于新方法发布之前水中石油类检测能力验证参加实验室的满意率。实验室在操作时的样品空白、正己烷透光率以及器皿污染控制等因素对检测结果的影响较大。目前市场上用于水质检测的石油类标准样品的来源较广泛,原料来源的不同可能导致标准量值存在差异,从而导致不同实验室的分析结果偏差较大。

Comparative Study on the Laboratories Performance of Testing Oil in Water After Implementation of the New Standard Methods

To promote the process of international compliance, usage of TCT for laboratory purpose was not permitted and the standard method Water quality-Determination of petroleum oils and animal and vegetable oils-Infrared spectrophotometry (HJ 637-2012) was invalid. Reassessment of laboratories performance of testing oil in water should be necessary after the two new standard methods, HJ 637-2018 and HJ 970-2018, were released at the end of 2018. The capabilities of laboratories testing oil in water by new standard methods were analyzed through two proficiency testing plans. The results showed that the percent of satisfactory of laboratories testing oil in water using UV spectrophotometry (UV, HJ 970-2018) and infrared spectrophotometry (IR, HJ 637-2018) was 79.1% and 86.6%, respectively. The percent of satisfactory of labs using UV was lower than the percent of satisfactory in prior similar proficiency testing plan and the percent satisfactory of labs using IR was higher than that. The sample blank, light transmittance of n-hexane and control of container contamination during testing process would effect the test results. The reference materials could access from several producers in market and the qualities of these RMs may not be consistent because of the source material different, which likely to cause the larger distribution range of the results from different laboratories.