Residual chlorine meter
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What is a residual chlorine meter that uses the polarization method, and what are the differences in its application compared to the DPD colorimetry method? This post was last edited by marry on 2009-3-27 at 15:32.]
DPD is the abbreviation for N,N-diethyl-p-phenylendiamine sulphate in English. When DPD reagent reacts with chlorine, it turns red, and the intensity of this red color increases as the chlorine concentration rises. The buffer pH range for measuring this reagent’s solution is pH 6.3. This is all the help I can provide; I’m also looking forward to answers from those who are more knowledgeable!
The polarization method for measuring residual chlorine is actually a physical technique; its key component is the ion-selective electrode. A stable voltage is applied during operation, and hypochlorous acid penetrates in, resulting in a polarization current. This current is proportional to the chlorine content and follows the Nernst equation. However, this aspect is greatly affected by temperature, pH, pressure, and impurities (such as ammonia nitrogen). This method is recognized by the U.S. EPA and does not cause secondary pollution. Colorimetry is generally less accurate than polarization method and is used less frequently than the latter.