一. Method Summary:
The polypropylene was ground into 20-mesh powder and then extracted by reflux or ultrasonic extraction with a mixture of dichloromethane and cyclohexane (75+25). The extraction solution was separated by liquid chromatograph and quantified by internal standard method.
二. Reagents and solutions:
1, 2 (2 'hydroxy-5' -methylphenyl) benzothiazole, 99%.
2. Vitamin E
3, erucamide, 99%.
4. (2, 4-di-tert-butylphenyl) phosphite, 99%.
5.phenylpropionate, 99%.
6, β (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid octadecanol ester, 99%.
7, 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid, 99%.
8, dichloromethane, cyclohexane, acetonitrile, isopropanol: chromatography pure.
9. T-p internal standard solution: Add tinuvin-P internal standard to dichloromethane - cyclohexane (75+25) mixed solution to prepare a mass fraction of 51.8mg/L solution.
三, liquid chromatographic conditions:
1, column: C18, 150mm*4.6mm, 5um.
2. Detection wavelength: 200nm.
3. Flow rate: 1.5mL /min.
4. Gradient program:
5, column temperature: 50℃.
6. Injection volume: 10ul.
四. Analysis Steps:
1. Sample preparation:
The grinding sample of 7-8g should be reduced as much as possible to avoid thermal decomposition of additives in the polymer. 5g samples were weighed in a 125ml flat-bottomed flask, 50ml internal standard solution was added, the cap was closed, and ultrasonic water bath was conducted for 90min. After finishing, cool to room temperature, shake well, filter through a membrane and set aside.
2, internal standard calibration:
Weigh 50mg of the component to be measured into a 125ml flask, add internal standard, dissolve it in 5-10ml hot isopropyl alcohol, move it to a 1000ml volumetric flask, dilute it to scale with isopropyl alcohol, and shake well. Vitamin E should be prepared on the same day and stored in brown volumetric bottles to prevent light breakdown.
3. Calculation of Results:
4. Chromatogram:
