Interlaboratory Excercise for Bromate Determination

Toxicological studies of bromate have provided continuous evidence of its possible carcinogenicity (Km-okawa et al, 1990). As a result a maximum admissible concentration (MAC) of 10 pg/L bromate in drinking waters is recommended by the US ERA (US EPA,1997), the Emopean Commission (Council Directive 98/83) and the WHO (WHO, 1991), this limit has been defined primarily on the basis of the detection 

Sample Number Matrix Natural background Spike level Total (target) level Grand mean of all labs 

2 High total hardness borehole water sample 0.3 2.7 2.7 2.62 

Five samples were prepared as test materials for the interlaboratory trial, of which the bromate content and matrix composition are given in Tables 2.8 and 2.9 respectively. 

The results obtained for the vast majority of the laboratories carrying out the ISO 15061 IC method were considered to be fit for the purpose. In addition to this method, five alternative methods suitable for trace bromate determinations were also considered, namely on-line IC-ICP-MS, simple on-line column chromatography ICP-MS, IC with chlorpromazine post-column reaction and colorimetric detection, and fluorescence quenching with Carbostyril (with pre-treatment), which are all capable of achieving a bromate detection limit below 1 xg/L. A field method with methylene blue and fluorescence quenching with Carbostyril without sample pretreatment did not lead to satisfactory results at this level of bromate concentrations. 

---