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Six, analysis and testing
(1) Sample preparation and dry matter content determination
Collect and preserve soil samples in accordance with the relevant requirements of HJ/T166
Determine the dry matter content in soil samples in accordance with the relevant requirements of HJ613
(2) Sample preparation
1.
Accurately weigh 5g (accurate to 0.
2.
Accurately weigh 0.
3.
Without adding soil samples, prepare water-soluble fluoride blank samples and total fluoride blank samples according to the same steps as the sample preparation
(3) Establishment of calibration curve
1.
Pipette 0mL, 0.
2.
Pipette 0mL, 0.
Table 9-7 Fluorine standard solution series
3.
From low mass concentration to high mass concentration, transfer the standard series of solutions to the beaker, insert the electrode, stir, and record the potential response value after the instrument reading is stable (the electrode potential response value fluctuates not more than 0.
(4) Sample measurement
1.
Accurately pipette 40.
0mL of the supernatant of the processed water-soluble fluoride sample (the pipetting amount can be reduced according to the fluoride content) into a 50mL volumetric flask, add 10.
0mL total ionic strength adjustment buffer solution, and dilute to the standard with water After mixing, measure the potential response value of the sample according to the same procedure
.
2.
Total fluoride
Accurately pipet 20.
0 mL of the supernatant of the processed total fluoride sample (the pipetting amount can be increased or decreased according to the fluoride content) into a beaker, add 1 to 2 drops of bromocresol purple indicator, and shake it gradually.
The hydrochloric acid solution was added dropwise until the solution changed from blue-violet to yellow
.
Transfer all the solution to a 50mL volumetric flask, add 10.
0mL total ionic strength adjustment buffer solution, dilute to the mark with water, and after mixing, measure the potential response value of the sample according to the same procedure
.
3.
Determination of blank sample
For the blank sample, determine the water-soluble fluoride and total fluoride according to the method steps of the sample determination
.
Related links: Determination of water-soluble fluoride and total fluoride in soil by ion selective electrode method (1)