SB/T 10405-2006Methods for wet ashing procedures for preparing wood for chemical analysis (English PDF)

3.1 Sampling method

Take a representative sample, the sampling site should avoid thrift, cracking and stress wood, and should be more than 30cm from the end. Hollow Drill sampling, when sampling with a hollow drill, the volume of the sample to be tested should be calculated.

3.2 Determination of density

The density of the sample was measured in accordance with GB/T 1933 wood density measurement method, expressed in kilograms per cubic meter (kg/m3).

3.3 Sample preparation method

The wood sample is comminuted to pass through a No. 30 standard sieve.

5.1 Principle

After the sample is decomposed by hydrogen peroxide-nitric acid, the element to be tested becomes soluble and then quantitatively determined.

5.2 Reagents

a) concentrated nitric acid (70%, AR);

b) Hydrogen peroxide (50%, AR).

5.3 Operation process

The wood powder sample is dried in an oven at 125 ° C for about 2.5 h to constant weight, and the analytical balance with a sensitivity of 0.1 mg is accurately weighed out about 5 g.

The sample was placed in a 500 mL flask, and 75 mL of concentrated nitric acid was slowly added along the wall of the bottle to completely wet the wood powder (equivalent to a test per gram of wood powder).

Add 15 mL of concentrated nitric acid). Add three glass beads and heat slowly on the hot plate;

After the initial reaction to form brown smoke, heating is continued until the solution becomes clear and transparent. Cool down, add 5mL peroxygen drop by drop