COD标准法光电比色波长的确定

针对标准法在线自动测试COD时经常会出现滴定终点判断不稳的情况,做了详细的误差分析,发现影响测量稳定性的主要误差因素为光电比色灵敏度,通过测量滴定过程中反应液在不同波长下透光度的情况,研究了光电比色波长对测量系统的灵敏度的影响,并确定了光电比色的最佳波长为450nm左右。实际应用结果表明,采用优选的比色波长,大大提高了滴定终点判别的稳定性,有效地提高了测量精度。

Ascertainment of photoelectric colorimetry wavelength in COD measuring

In the course of COD online automatic measuring,there were always the facts that the judgement of the titration end-point was unstable.In allusion to this instance,detailed analytical study on the errors was made and found that the main factor was the sensitivity of photoelectric colorimetry. At last, the best photoelectric colorimetry wavelength-about 450 nm was decided based on the experiment by measuring the light intension in different-colorimetric wavelength in the course of titration.The result indicates that the stability of judging the titration end-point is improved distinctly if the selected wavelength in this paper is used,which increases the measuring precision effectively.