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What is the measuring method of COD rapid tester?

by:BOQU     2021-06-02


What is the measurement method of the COD rapid tester? What are the advantages of the COD rapid tester? Many friends who have just touched the water quality monitoring profession don't know much about these, and some people use them, but they don't know the principle. If you don’t know, let’s take a look at Guanao Instruments.

Summary of COD rapid tester detection method:

COD rapid tester is an indispensable item in water quality monitoring. Its meaning refers to the amount of oxidant consumed when a strong oxidant is used to treat water samples under certain conditions.

Indicated by the mg/L of oxygen, the chemical oxygen demand reflects the degree of water pollution by reducing substances. In the process of detection and analysis, the Cl- in the water sample is easily oxidized by the oxidizing agent. A lot of Cl- makes the determination result high. The determination of high-chlorine and low-COD wastewater is a difficult problem now. In practice monitoring, it was found that many kinds of wastewater, such as chemical wastewater, monosodium glutamate wastewater, and seafood processing wastewater, have high Cl- content. The COD water quality detector needs to be shielded and then measured for Cl-.

The majority of environmental monitoring operators have done a lot of work on the interference of Cl- to COD measurement. The following discusses the two aspects of the Cl- influence method and the existing Cl- interference elimination method.

Operation principle of COD rapid tester detection method:

A quantitative potassium dichromate solution is added to the sample. In a strong acid medium, silver sulfate is used as a catalyst. After high temperature and high-pressure digestion, the COD concentration value is determined by spectrophotometry.

Measure the absorbance of trivalent chromium (Cr3+) generated by the reduction of potassium dichromate at a wavelength of 600nm. The concentration of the sample's COD water quality detector has a linear relationship with the absorbance of trivalent chromium (Cr3+). Based on this relationship, the absorbance of trivalent chromium (Cr3+) can be converted into the concentration value of the sample COD water quality detector.

Features of COD water quality detector detection method:

1. The selection of the scenery light compensation mechanism reduces the influence of the drift of the LED output light intensity over time, improves the accuracy and repeatability of the measurement, and reduces the detection constraints of the instrument.

2. The temperature compensation mechanism is selected to reduce the influence of environmental temperature changes on the measurement, improve the accuracy and repeatability of the measurement, and reduce the detection constraint of the instrument.

3. The low-pass noise reduction algorithm is selected, which improves the accuracy and repeatability of the measurement and reduces the detection constraint of the instrument.

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