SN/T 5229-2019Determination of isothiazolinone preservatives in toy materials by liquid chromatography-mass spectrometry (LC-MS) method (English PDF)

6.1 Sample preparation

6.1.1 Aqueous liquid

Accurately weigh 1.0 g sample, accurate to 1 mg, place it in a 50 mL polypropylene test tube, add water to 15 mL, and ultrasonically extract for 20 minutes Filtered with 0.22 µm filter membrane, to be tested.

6.1.2 Sticker samples with adhesive

Take representative samples of different colors from the sticker samples. Cut into small pieces less than 3mm on each side, and mix well. Accurately weigh 1.0 g the sample is accurate to 1 mg, placed in a 50 mL polypropylene test tube, add water to 15 mL, ultrasonically extract for 20 minutes, and filter with a 0.22 µm filter membrane.

To be tested.

6.1.3 Modeling clay samples

Accurately weigh 1.0 g of the above sample, accurate to 1 mg, place it in a 50mL polypropylene test tube, add water to 15mL, and ultrasonically extract 20 min, 0.22 µm filter membrane filter, to be tested.

6.1.4 Leather samples

Select representative samples from different colors or different parts of the leather samples, the sample area is not less than 10 cm2.The sample is cut to a small length on each side in 3 mm small pieces, mix well. Accurately weigh 1.0 g of the above sample, accurate to 1 mg, place it in a 50mL polypropylene test tube, and add water to 15mL, ultrasonic extraction for 20 minutes, 0.22 µm filter membrane filtration, to be tested.

6.1.5 Blank test

Except that no sample is added, other tests shall be carried out according to the test procedure 6.3.

6.2 Solution configuration

6.2.1 Configuration of standard solution

Weigh 10 mg (accurate to 0.1 mg) of MI, CMI, and BIT standards respectively in a 50 mL volumetric flask, and use 0.4% acetic acid the solution (5.3) has a constant volume and is made into 3 standard stock solutions with a mass concentration of.200 mg/L.

6.2.2 Configuration of standard stock solution

Accurately pipette the above three standard stock solutions and dilute them with deionized water to obtain three preservatives with mass concentrations of 5.0µg/L, 10µg/L, 20µg/L, 50µg/L, 100µg/L,.200µg/L, 500µg/L series of mixed standard solutions (If the sample concentration exceeds the concentration range, press Properly dilute the ratio; you can also choose the appropriate curve concentration range according to the actual situation).

6.3 Determination

6.3.1 LC-MS conditions

Depending on the instrument used, the optimal analysis conditions may be different, so it is impossible to give general parameters suitable for all LC-MS. set up the parameters should ensure that the tested combination is effectively separated and determined. The parameters listed below have been proven to be feasible, and the spectra can be found in Appendix A.

6.3.2 Determination

According to the data in Table 1, the mass spectrum peaks of each isothiazolinone preservative were collected.

7.1 Qualitative results

The sample was qualitatively judged by liquid chromatography-tandem mass spectrometry. Under the same test conditions, the mass color of the tested components in the sample the retention time of the spectral peak is consistent with the retention time of the mass chromatographic peak of the corresponding component in the standard solution; and the mass-to-charge ratio of the selected two pairs of product ions Consistent, the deviation between the relative abundance ratio of the selected monitoring ion pair in the sample chromatogram and the ion relative abundance ratio of the standard solution of equivalent concentration If it does not exceed the range specified in Table 2, it can be determined that the corresponding components are present in the sample.

7.2 Quantitative calculation

Measure the standard solution and sample solution under the same experimental conditions, make a standard curve, and use the content of isothiazolinone preservatives in the sample the external standard method is used for quantification and the content is calculated according to formula (1).

omega --The content of preservatives in toys, mg/kg c - Obtain the mass concentration of the component to be tested from the standard curve, µg/L;

V --The constant volume of the sample, mL;

m --sample sampling volume, g.

8 Detection limit, quantification limit and detection concentration, minimum quantification concentration this method measures 2-methyl-4-isothiazolin-3-one (MI) and 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) the lower limit is 0.075mg/kg, and the lower limit for 1,2-benzisothiazolin-3-one (BIT) determination is 0.030mg/kg.