YS/T 1028.2-2015Methods for chemical analysis of lithium iron phosphate. Part 2: Determination of lithium content. Flame photometry (English PDF)

3.4 Lithium standard solution (100 µg/mL). Transfer 10.00 mL of lithium standard

stock solution (3.3) into a 100 mL volumetric flask, add 2 mL of sulfuric acid (3.2), dilute with water to the mark, and mix well.

6.1 Specimen

Weigh 0.20 g of the sample, accurate to 0.0001 g.

6.2 Number of measurements

Perform two independent measurements and take the average value.

6.3 Blank test

A blank test is performed along with the sample test.

6.4 Measurement

6.4.1 Place the specimen (6.1) in a 250 mL beaker, moisten it with a small amount of water, add 20 mL of hydrochloric acid (3.1), cover it with a watch glass, heat it to a gentle boil for 3 to 5 minutes, then remove it and cool it to room temperature; rinse the watch glass with a small amount of water, filter it with rapid filter paper, and wash the beaker and filter paper with water 5~7 times. Collect the filtrate in a 250 mL volumetric flask, dilute it with water to the mark, and shake well.

6.4.2 Transfer 25.00 mL of the test solution (6.4.1) to a 100 mL volumetric flask, add 2 mL of sulfuric acid (3.2), dilute to the mark with water, and shake well. Zero the flame photometer with water and determine the lithium concentration.

6.5 Drawing the working curve

6.5.1 Transfer 0 mL, 5.00 mL, 10.00 mL, 15.00 mL, and 20.00 mL of lithium standard solution (3.4) into a set of 100 mL volumetric flasks, add 2 mL of sulfuric acid (3.2), dilute with water to the mark, and shake well.

6.5.2 Using a flame photometer, determine the excitation intensity of lithium in a series of standard solutions, and plot the working curve with lithium concentration as the abscissa and excitation intensity as the ordinate.