Which method is used for testing residual chlorine while minimizing interference?

The DPD-colormetric method is often favored for testing residual chlorine because it effectively minimizes interference from other compounds typically found in water samples. This method involves the use of DPD (N,N-diethyl-p-phenylenediamine), which reacts with chlorine to produce a pink-colored complex.

One of the key advantages of the DPD-colormetric method is its ability to provide rapid and straightforward visual results through color intensity measurement, allowing for timely assessments of chlorine levels. The specificity of this method to chlorine makes it less susceptible to interference from substances like bromine or other oxidants, which can complicate readings in alternative methods. This specificity is crucial in ensuring that the results accurately reflect the concentration of chlorine present without being skewed by additional chemicals in the sample.

In contrast, other methods might encounter challenges when it comes to interference. For example, techniques like the Leuco crystal violet method or the DPD-titrimetric method may have limitations that affect their accuracy under certain conditions. Therefore, the DPD-colormetric method is typically recommended for reliable chlorine measurement while reducing the likelihood of false positives or inaccuracies due to interference.