SN/T 1588.3-2013Rules for the inspection of luminaires for import and export - Part 3: Particular requirements of luminaries for swimming pools and similar applications (English PDF)

5.5 Dipotassium hydrogen phosphate buffered extraction solution (0.1 mol/L): Dissolve

22.822 g of dipotassium hydrogen phosphate in water. Add nearly 1000 mL of water.

Mix well. Use phosphoric acid solution or potassium hydroxide solution to adjust the pH to pH 7.9 ~8.1. Set the volume to 1000 mL.

5.6 Hexavalent chromium standard solution: 100 mg/L hexavalent chromium standard

solution. It is certified reference material.

5.7 Hexavalent chromium standard stock solution: Dilute the hexavalent chromium

standard stock solution with water step by step to a 100 µg/L solution. Prepare when needed.

5.8 Hexavalent chromium standard curve solution: Pipette 0 mL, 0.125 mL, 0.5 mL,

1.25 mL, 2.5 mL, and 5 mL of standard stock solution (5.7) into 25 mL volumetric flasks. Set the volume up to the mark with water. Mix well. The standards of this standard series are: 0 µg/L, 0. 5 µg/L, 2 µg/L, 5 µg/L, 10 µg/L, and 20 µg/L. Prepare when needed.

5.9 Mobile phase (56 mmol/L nitric acid-67 mmol/L ammonia, pH 9.0): Accurately

pipet 2.00 mL of nitric acid and 2.50 mL of ammonia solution into a beaker. Add nearly

500 mL of water. Mix well. Adjust the pH to 9.0 with ammonia or nitric acid solution, and transfer it to a 500 mL volumetric flask. Set the volume to the mark with water.

Conduct ultrasonic degassing for 10 min.

6.1 High performance liquid chromatography-inductively coupled plasma mass

spectrometer.

6.2 Ultrasonic generator.

6.3 Vortex mixer.

6.4 Oscillator.

6.5 Refrigerated centrifuge: the rotation speed is greater than 10000 r/min; the minimum temperature is less than 4°C.

6.6 Analytical balance: sensitivity is 1 mg.

7.1 Specimen preparation

Take about 500 g of representative sample from all the samples taken. Grind solid samples to powders. Those with high moisture content are beaten into a paste. Mix well.

Divide into two equal portions. Put them into clean containers separately. Seal them as specimens. Indicate the mark.

For health care capsule samples, discard the capsule shell and remove the entire contents.

7.2 Specimen storage

Specimens with high moisture content shall be frozen and stored below -18°C.

8.1 Sample processing

Weigh 0.5 g of powder sample and 0.5 g~1.0 g (accurate to 0.001 g) of the sample with high moisture content in a 50 mL centrifuge tube. Add dipotassium hydrogen phosphate extraction solution (5.5). Dilute to 25 mL. The sample is vortexed for 2 min, ultrasonic extracted for 20 min, extracted on a shaking table for 30 min, and centrifuged at 10000 r/min for 5 min. Take 4 mL of the supernatant into a 15 mL centrifuge tube. Add 1 mL of n-hexane. Then conduct high-speed centrifugation at 10000 r/min for 5 min. Remove

2 mL of supernatant. Pass through a 0.45 µm aqueous phase filter membrane and wait for measurement on the machine. Complete the measurement within 2 h.

8.2 Determination

8.2.1 Liquid chromatography reference conditions

Liquid chromatography reference conditions are listed below:

a) Chromatographic column: anion exchange column, 250 mm × 4.1 mm (inner diameter), 10 µm, or one with equivalent performance.

b) Mobile phase: 56 mmol/L nitric acid-67 mmol/L ammonia, pH 9.0 (5.9).

c) Flow rate: 1.0 mL/min.

d) Injection volume: 50 µL.

8.2.2 Inductively coupled plasma-mass spectrometry conditions

10.1 Limit of quantification (LOQ)

The limit of quantitation of this method is 0.05 mg/kg.

10.2 Recovery rate and precision

The recovery and precision results of this method at the added concentration are shown in Table C.1.

Method Two -- Ion chromatography post-column derivatization

12.10 Post-column derivatization solution: Weigh 0.4 g of diphenylcarbazide. Dissolve

with 50 mL of methanol. Transfer to a 500 mL volumetric flask. Measure 50 mL of 2 mol/L sulfuric acid and add it to the 500 mL volumetric flask. Shake well. Add water to set the volume to the mark.

12.11 Hexavalent chromium standard solution: 100 mg/L hexavalent chromium

standard solution. It is certified reference material.

12.12 Hexavalent chromium standard stock solution: see (5.7).

12.13 Hexavalent chromium standard curve solution: see (5.8).

12.14 Mobile phase: Accurately pipet 2.5 mL of nitric acid and 3.5 mL of ammonia solution into a 500 mL volumetric flask. Use water to set the volume to the mark.

Conduct ultrasonic degassing for 10 min.

13.1 Ion chromatograph with post-column derivatization device, diode array or UV-

visible detector.

13.2 Ultrasonic generator.

13.3 Vortex mixer.

13.4 Oscillator.

13.5 Refrigerated centrifuge: the rotation speed is greater than 10000 r/min; the minimum temperature is less than 4°C.

13.6 Analytical balance: sensitivity is 1 mg.

15.1 Sample processing

See 8.1.

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