"HJ 613 Soil Dry Matter and Moisture Determination Gravimetric Method", "HJ/T 166 Soil Environmental Monitoring Technical Specification"
Instruments and equipment
1. Infrared oil detector or infrared spectrophotometer: absorbance can be measured at 2930 cm-1, 2960 cm-1, 3030 cm-1, and equipped with a 40 mm quartz cuvette with lid.
2. Horizontal oscillator: The frequency of oscillation is (150~250) times/min.
3, muffle furnace.
4. Balance: The sensitivity is 0.01 g and 0.0001 g.
5, with a conical flask: 100 ml.
6. Glass funnel: 60 mm in diameter.
7. Sampling bottle: 500 ml, wide-mouth brown glass bottle with Teflon liner.
8, common laboratory utensils and equipment.
Preparation of sample
20.0 ml of tetrachloroethylene (5.1) was placed in an Erlenmeyer flask (7.2), sealed, placed in an oscillator (6.2), and extracted with a frequency oscillation of 200 times/min for 30 min. After standing for 10 min, the extract was filtered into a 50 ml colorimetric tube using a glass funnel (6.6) with a glass fiber filter (5.8). The extraction was repeated once with 20.0 ml of tetrachloroethylene (5.1), and the extract and the sample were all transferred and filtered. The stoppered conical flask, filter, glass funnel and soil samples were washed with 10.0 ml of tetrachloroethylene (5.1) and the extracts were combined. Pour the extract into the adsorption column (5.18), discard the first 5 ml of the effluent, and retain the remaining effluent for testing.
Correction factor test
Each batch of samples should be tested for the correction factor. When using, take appropriate amount of petroleum standard use solution (5.16) according to the required concentration, and prepare the appropriate concentration of petroleum standard solution with tetrachloroethylene as solvent. 8.2) The same procedure is carried out to determine the concentration of the petroleum standard solution according to formula (1). If the relative error between the measured value and the standard value is within ±10%, the correction factor can be used, otherwise the correction coefficient is re-measured and tested until the condition is met. It can also be tested using certified reference materials/samples.