BY VISIBLE SPECTROPHOTOMETRY

1.1 This is a spectrophotometric method for the analysis of chlorine dioxide and chlorite * in finished drinking waters. It is primarily intended to be used at drinking water utilities in conjunction with daily monitoring requirements. 1.2 The experimentally determined Detection Limits (DLs) for chlorine dioxide and chlorite are provided in Section 17, Table 1. The DL is defined as the statistically calculated minimum concentration that can be measured with 99 % confidence that the reported value is greater than zero. Detection Limits are technique and instrument dependent. (1) The DL differs from, and is lower than, the Minimum Reporting Level (MRL) (Sect. 3.10). Method performance was demonstrated over a combined concentration range of 0.2 mg/L to 2.2 mg/L. Precision and accuracy data are presented in Section 17, Tables 1-3. 1.3 Chlorine dioxide is a volatile, reactive gas. Care was taken during method development to minimize steps that could result in the loss of chlorine dioxide during analysis. Analyst technique can affect method precision and accuracy. 2. SUMMARY OF METHO