GB/T 38744-2020Methods for chemical analysis of synergistic catalysis elements in automotive exhaust catalysis－Determination of cerium, lanthanum, praseodymium, neodymium,barium and zirconium contents－Inductively coupled plasma atomic emission spectrometry (English PDF)

3.10 Lanthanum standard storage solution

Weigh 0.1173g of high-purity lanthanum trioxide (La2O3) that has been burnt at 850°C. Place in a beaker.

Use water to moisture. Add 20mL of hydrochloric acid (3.5). Heat at a low temperature till it is dissolved. After cooling, move into a 100mL volumetric flask.

Use water to dilute to the scale. Mix well. 1mL of this solution contains 1000µg of lanthanum.

3.11 Praseodymium standard stock solution

Weigh 0.1208g of high-purity praseodymium oxide (Pr6O11). Place in a beaker. Add 30mL of mixed acid of hydrochloric acid and nitric acid (3.8). Heat at a low temperature till it is dissolved. After cooling, move into a 100mL volumetric flask. Use water to dilute to the scale. Mix well. 1mL of this solution contains 1000µg of praseodymium.

3.12 Neodymium standard stock solution

Weigh 0.1166g of high-purity neodymium trioxide (Nd2O3). Place in a beaker. Add 40mL of hydrochloric acid (3.5). Heat at a low temperature till it is dissolved. After cooling, move into a 100mL volumetric flask. Use water to dilute to the scale. Mix well. 1mL of this solution contains 1000µg of neodymium.

3.13 Barium standard storage solution

Weigh 0.1437g of high-purity barium carbonate (BaCO3) that has been dried at 105°C for 2h. Place in a beaker. Add water and 20mL of nitric acid (3.6). Heat at a low temperature till it is dissolved.

After cooling, move into a 100mL volumetric flask. Use water to dilute to the scale. Mix well. 1mL of this solution contains 1000µg of barium.

6.3 Blank test

Conduct blank test with test materials.

6.4 Determination

6.4.1 Place the test material (6.1) in a 30mL Teflon digestion tank. Add 12mL of hydrochloric acid (3.1), 3mL of nitric acid (3.2), 2mL of hydrogen peroxide (3.3), 0.3mL (about 8 drops) of hydrofluoric acid (3.4). Tighten the lid. Place in an oven at a constant temperature of 150°C for 12h. Take it out. Open the tank after cooling to room temperature. Use distilled water to transfer all samples into a 200mL beaker. Steam on an electric stove to about 10mL. Move into a 100mL volumetric flask. Use

6.4.2 Preparation methods

STD-1: Pipette 1.00mL of mixed standard solution I (3.15) and 0.50mL of mixed standard solution II (3.16) respectively into a 100mL volumetric flask. Use hydrochloric acid (3.7) to dilute to the scale. Mix well.

STD-2: Pipette 5.00mL of mixed standard solution I (3.15) and 5.00mL of mixed standard solution II (3.16) respectively into a 100mL volumetric flask. Use hydrochloric acid (3.7) to dilute to the scale. Mix well.

STD-3: Pipette 2.00mL of cerium and zirconium standard stock solutions (3.9, 3.14), 1.00mL of lanthanum, praseodymium, neodymium, and barium standard stock solutions (3.10~3.13) respectively into a 100mL volumetric flask. Use hydrochloric acid (3.7) to dilute to the scale. Mix well.

STD-4: Pipette 5.00mL of cerium and zirconium standard stock solutions (3.9, 3.14), 2.50mL of lanthanum, praseodymium, neodymium, and barium stock solutions (3.10~3.13) respectively into a 100mL volumetric flask. Use hydrochloric acid (3.7) to dilute to the scale. Mix well.

STD-5: Pipette 10.00mL of cerium and zirconium standard stock solutions (3.9, 3.14), 5.00mL of lanthanum, praseodymium, neodymium, and barium standard stock solutions (3.10~3.13) respectively into a 100mL volumetric flask. Use hydrochloric acid (3.7) to dilute to the scale. Mix well.

6.4.3 Drawing of working curve: Prepare the standard solution shown in Table 2. Make working curve under selected ICP-AES instrument conditions. The linear correlation coefficient of the working curve of each element shall be >=0.9995.