Improvement of spectrophotometric method based on Russell mechanism for detection of ?OH concentration in liquid

摘要

Spectrophotometric method based on Russell mechanism for detection of?OH concentration in liquid has many advantages, such as low-cost, simple operation, and so on. However, low precision and poor repeatability are its main disadvantages. The reason of this method's low precision was elucidated, and a modified method was proposed. The influence of typical cations and anions on extraction of Fast Blue BB salt (FBBs) was analyzed. Key operating conditions for the modified method was determined. Based on the results, a relationship between?OH concentration and absorbance of diazosulfones was rebuilt. The interference of FBBs in the diazosulfone extraction process is the main reason of low precision. FeSO4 has a strong ability to hold back extraction of FBBs by extraction agent, which decreases influence of FBBs on diazosulfones detection violently. Na+, K+, NO3- do not have obvious effects on the detection result, while Cl- influence is in relation to its concentration. The conditions for the modified method are: extraction time 300 s and molar ratio of FBBs to methylsulfinic acid (MSIA) is 50. The function relationship between?OH concentration and absorbance is obtained.

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