Melamine Powder CAS 108-78-1 Melamin

S1. Prepare melamine standard solutions of different concentrations as 0mg/kg, 15mg/kg, 25mg/kg, 45mg/kg, 100mg/kg;

S2. Add the standard solution of melamine in S1 into the milk powder dissolving solution respectively, and mix them thoroughly to obtain several mixed solutions;

S3. Mix the mixture in step S2 with 99.8% absolute ethanol at a ratio of 1:1.5, and centrifuge to obtain the supernatant liquid;

S4. Drop the clarified liquid in step S3 on the metal evaporating dish respectively, and dry the metal evaporating dish;

S5. The melamine in the melamine standard solution is detected by confocal microscopy Raman spectroscopy and the Raman spectra are obtained, and they are numbered D1, D2, D3, D4, and D5;

S6. Perform confocal Raman spectroscopy detection of the residual melamine on the evaporating dish in S4 to obtain a Raman spectrum, and number the evaporating dishes as T1, T2, T3, T4, and T5;

S7. Compare the Raman peaks of D1, D2, D3, D4, D5 with T1, T2, T3, T4, and T5 respectively to determine whether the milk powder contains melamine.

Step a: Calibration standard melamine aqueous solution

Dissolve 0g to 0.035g of melamine in 100ml of distilled water, drop 20ml of melamine aqueous solution on the sheet, use an ion mobility spectrometer to detect, and measure the ions to reach the ion peak position of the ion mobility spectrometer detector; choose distilled water to avoid other things in the water Impurities affect the solubility of melamine;

The temperature of the distilled water is 0°C, the distilled water at this temperature is easy to obtain, and the temperature error is the smallest, so the detection accuracy can be improved;

The described 0g to 0.035g melamine, the step size is 0.001g, that is to choose 0g, 0.001g, 0.002g, up to 0.035g, a total of 36 values, the measurement results can be divided into 36 levels, the detection results are more accurate, At the same time, the influence of some interference factors can be overcome.

Step b: Configure the saturated milk solution

Mix the milk powder and the distilled water with the same temperature in step a according to the volume ratio of 1:2~2:1 to form a paste, and then pass the filter paper to obtain a saturated milk solution;

Step c: Test the saturated milk solution

Take 20ml of saturated milk solution and drop it on the sheet, use the ion mobility spectrometer to detect, and measure the time and peak intensity of ions reaching the ion mobility spectrometer detector;

Step d: Determine the melamine content in the saturated milk solution

Determine the peak intensity of melamine in the result obtained in step c through the position of the ion peak obtained in step b, thereby determining the content of melamine.