GB/T 24167-2022Determination of chlorinated toluenes in dye products (English PDF)

6.5 Extractor: tube with stopper, 10mL

6.6 Centrifuge: 4000r/min.

6.7 Nitrogen blowing concentrator.

7.1 Chlorinated toluene single standard stock solution

Respectively take 10mg of the standard substances listed in Appendix A, accurate to 0.01mg; dissolve with dichloromethane and make constant volume to a 10mL volumetric flask to prepare a single standard stock solution containing 1000mg/L of chlorinated toluene. The single standard stock solution shall be kept under 4 °C and protected from light, sealed and refrigerated; and the validity period is one month. Also certified standard solutions, such as single- component chlorinated toluene standard solutions or chlorinated toluene mixed standard solutions can be directly purchased.

7.2 Chlorinated toluene mixed standard working solution

Pipette 0.5mL of each single standard stock solutions of chlorinated toluene (see 7.1) to 10mL volumetric flasks; dilute to the mark with dichloromethane; and prepare a standard working solution containing 50mg/L of chlorinated toluene.

7.3 Standard working solutions

Use chlorinated toluene mixed standard working solution (see 7.2) to prepare the standard working solution; and the appropriate concentration can be prepared according to the content of the target substance in the specimen. m - the mass value of the specimen, in g.

The calculation result is rounded-off to two digits after the decimal point.

The calculation results are rounded-off according to the provisions of GB/T 8170-2008.

11.1 Detection limit

When using the Method-I in Clause 8 to prepare sample solution, the detection limit of 12 chlorinated toluenes shall be 0.5mg/kg. When using the Method-II to prepare the sample solution, the detection limit is 2.5mg/kg.

11.2 Precision

In the same laboratory, the absolute difference between two independent measurement results obtained by the same operator using the same equipment, according to the same measurement method, and independently of each other on the same measured object in a short period of time is no greater than 20% of the arithmetic mean of the two determination results.

11.3 Accuracy

Use the standard addition method, add an appropriate amount of chlorinated toluene standard solution to 1g of dye specimen; and the concentration of the standard addition is 10mg/kg.

Operate according to the provisions of Clause 8; and the measured recovery rate of various chlorinated toluenes shall be 70% ~120%.