This method is applicable to the determination of hydrogen ion concentration of pesticide emulsifiers. GB 3776.2-1983 Determination of hydrogen ion concentration of pesticide emulsifiers GB3776.2-1983 Standard download decompression password: www.bzxz.net

1 Scope of application
National Standard of the People's Republic of China
Method of hydrogen ion concentrationdetermination for pesticide emulsifiers This method is applicable to the determination of hydrogen ion concentration of pesticide emulsifiers. 2 Reagents and solutions
2.1 Distilled water: pH value 6.5~7.0.
2.2 Potassium dihydrogen phosphate (GB1274-77): analytical grade. 2.3 Disodium hydrogen phosphate (GB1263--77): analytical grade. UDC 66.063.61
GB 3776.2-83
(confirmed in 1989)
2.4 Preparation of standard buffer solution: Weigh 3.04 g potassium dihydrogen phosphate and 3.55 g disodium hydrogen phosphate that have been dried to constant weight at 110°C, dissolve in distilled water without carbon dioxide, and dilute to 1 liter. The pH value of this solution is 6.86 (25°C). 2.5 The pH value of the standard buffer solution at different temperatures is as follows: Temperature (°C)
3 Instrument
pH value of phosphoric acid type standard buffer solution
Temperature (°C)
pH meter: accurate to 0.1, requires temperature compensation or temperature calibration chart. 4 Instrument calibration
4.1 Glass electrode: Soak in distilled water for 24 hours before use. Phosphoric acid type standard buffer solution pH value wwW.bzxz.Net
4.2 Saturated calomel electrode: The cavity of the electrode needs to be filled with saturated potassium chloride solution, and a small amount of potassium chloride crystals must be present at any temperature.
4.3 First adjust the pointer to zero, then put the electrode into the standard buffer solution, and adjust the pointer of the instrument to the pH value of the standard buffer solution at that temperature. Repeat twice. When the pH value reading of the standard buffer solution remains unchanged, the instrument can be used. 4.4 When calibrating the instrument, the standard buffer solution used should be as close as possible to the pH value of the object to be measured. If the zero point changes after continuous use for a long time, the zero point should be readjusted and calibrated according to the steps in 4.3. 5 Determination procedure
Take 0.5 ml of pesticide emulsifier in a 50 ml beaker and add 49.5 ml of distilled water. After stirring with a glass rod, put the calomel electrode and glass electrode into the solution to be measured and measure its pH value. If the pointer changes no more than 0.1 pH value within 2 minutes, the reading is the pH value of the sample.
Additional Notes:
GB 3776.2—83
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is technically managed by the Shenyang Chemical Research Institute of the Ministry of Chemical Industry. This standard was drafted by Nanjing Zhongshan Chemical Plant. The main drafters of this standard are Zhang Junzhi and Tao Deming. 612
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