Permanganate index (CODmn) reagent simple operation process

Author: 同奥科技

Abstract: 本文介绍了高锰酸盐指数（CODmn）试剂的简易操作流程。测试前需根据预判的CODmn浓度范围选择相应操作步骤和量程。消解过程可使用消解仪或水浴锅，加热时间需严格控制。根据预判值选择CODmnL或CODmnH的分析程序，如超出范围需稀释样品。操作中应防止交叉污染，选择适当的移液工具，并定期校准移液枪。水样的紫红色深浅与CODmn浓度成正比，分析结果应乘以稀释倍数以获得准确值。

Concentration prediction:

Before testing the water sample, first predict the CODmn value of the water sample and select the operation steps corresponding to the range, for example, predict the CODmn concentrationIf the degree value is 0-5mg/L, you need to select the operation step of the 0-5mg/L range; If the CODmn concentration is predicted to be 5-10mg/L, the 5-10mg/L range is chosenProcedure.

Notes:

The digestion of CODmn can be digested by a digester or a Water Bath, and the time should be strictly controlled.

(1) When using a Water Bath to heat, put in blank and water samples after the water boils, and start the timer when the water starts to boil again, reaching a time of 13minImmediately after that, the blank and water samples should be removed and placed in water to cool rapidly.

(2) When using the digestion instrument for heating, when the digestion instrument completes the temperature rise alarm, put the blank and water samples into the digestion instrument to start digestion, and report again when the digestion instrument reportsAfter the alarm, the blank and water samples should be taken out immediately and placed in water to cool rapidly.

1. When the predicted value is in the range of 0 0- -L 5mg/L

If CODmn is present, the water sample appears purplish-red, and the darker the color, the higher the concentration value. Analysis Procedure: CODmnL; Watch out for overrange tips!

The simple operation process of the permanganate index (CODmn) reagent is shown in Figure 1

2. When the predicted value is in the range of 5 5- - 10L mg/L

If CODmn is present, the water sample appears purplish-red, and the darker the color, the higher the concentration value. Analysis Procedure: CODmnH; Watch out for overrange tips!

The simple operation process of the permanganate index (CODmn) reagent is shown in Figure 2

3. When the predicted value exceeds 10 mgL /L

The water sample needs to be diluted to the corresponding concentration value in sections 1-2 above, and then operated according to the corresponding range, and the determination result is multiplied by the dilution factor.

4. Test steps on the computer

The simple operation process of the permanganate index (CODmn) reagent is shown in Figure 3

5. Precautions

◆ If there is CODmn, the water sample shows purple-red, and the darker the color, the higher the concentration value of the water sample.

◆ Pay attention to cross-contamination, use different measuring utensils for different liquids (pay attention to changing the tip when using a pipette).

◆ Use appropriate pipetting tools to take liquids, and large range measuring tools cannot measure small volumes of water samples, such as: 5mL pipettes cannot be used to remove 2mL and below liquidsFor liquids less than or equal to 2mL, it is recommended to pipette twice with a 1mL pipette.

◆ When using a pipette, it is necessary to calibrate the pipette frequently (it is recommended to do so once a week), and pay attention to replacing the tip during use.