重铬酸盐法测定水中COD质量控制指标研究

The Quality Control Index on the Dichromate Method for the Analysis of COD in Water

通过全国多家实验室的大量监测数据,研究分析了COD测定的质量控制指标,并与GB/T 11914—1989和ISO6060—1989进行了比较,旨在为环境监测工作提供质量控制依据和质量控制指标。研究表明,标准样品RSD的质量控制范围:≤3.5%,实际样品:≤5.5%。实验室间标准偏差为3.0～6.0mg/L,RSD′可根据浓度水平和数据质量目标在3%～10%之间进行选择。相对误差一般在10%左右,低浓度可以控制在20%以内,高浓度时在5%以内。加标回收率范围为98%～110%。

On the basis of a large number of monitoring data from many laboratories nationwidely,we analyzed the quality control index of the COD,and compared with the QC index in GB /T 11914-1989 and ISO 6060.The purpose of which was to provide the QC reference and QC index for the people in the monitoring area.Studies indicate that the within-laboratory relative standard deviation control limit of standard samples was less than 3.5%,that of actual samples wan less than 5.5%.The between-laboratory standard deviation control limit ranges beween 3.0 and 6.0 mg /L,RSD′ can be ranged beween 3% and 10% according to the concentration and the data qulity objectives.The relative error of the standard samples was about 10%,at high concentration level,it can be limited in range of 20%,at low concentration,of 5%.The correspounding recovery rates was less than 98%～110%.