GB/T 6609.19-2018 in English

Atomic Absorption Spectrometer: Equipped with a lithium hollow cathode lamp, characteristic concentration ≤0.075 μg/mL, and strict precision requirements (the absorbance standard deviation of the highest concentration standard solution does not exceed 1.0%, and the lowest concentration does not exceed 0.5%).

Polytetrafluoroethylene sealed sample dissolver: used for high temperature dissolution of samples

Oven: rated temperature ≥350°C, temperature control accuracy ±3°C

5.1 Sample preparation

The sample must pass through a 0.125 mm standard sieve and be dried at 300°C±10°C for 2 hours before use.

5.2 Analysis steps

1. Weigh 0.50 g sample, accurate to 0.0001 g
2. Add 8 mL hydrochloric acid (1+1), seal and place in a polytetrafluoroethylene sample dissolver
3. Heat to 240°C±3°C and keep warm for 6 hours. Cool naturally and then process the test solution
4. Select different dilution factors R according to the lithium oxide content range (≤0.04% or >0.04%~0.20%)
5. Draw a working curve, measure the absorbance of the test solution, and calculate the mass fraction of lithium oxide

Laboratories should calibrate instruments regularly and use standard samples for verification. Operators must undergo professional training to ensure that the experimental environment meets the requirements (such as temperature control and equipment maintenance). It is recommended to establish a quality control system, including blank tests and repeatability checks.

For high-content samples (>0.04%), special attention should be paid to the selection of dilution multiples to avoid exceeding the linear range of the instrument. The drawing of the working curve should ensure its accuracy, and it is recommended to redraw it at regular intervals.