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4 Test method
Unless otherwise specified, only reagents confirmed to be analytically pure and grade 3 water in compliance with GB/T6682-2008 are used in the analysis
The standard titration solutions, preparations and products used in the analysis are prepared in accordance with the provisions of GB/T601-2002 and GB/T603-2002 when other requirements are not specified
4.
Under natural light or fluorescent light, spread (5-10) g of laboratory samples on clean white paper and observe visually
4.
4.
The trimethylolpropane and impurity components in the sample react with acetic anhydride to generate corresponding esterified derivatives.
4.
4.
4.
4.
4.
4.
4.
4.
4.
4.
2.
3.
4 Sample injector: 1uL glass syringe or automatic sample injection valve
.
4.
2.
4 Chromatographic column and typical operating conditions
The chromatographic column and chromatographic operating conditions recommended by this standard are shown in Table 2
.
For typical chromatograms and relative retention values of each component, see Figure A.
1 and Table A.
1 in Appendix A.
Other chromatographic columns and chromatographic operating conditions that can achieve the same degree of separation can also be used
.
Table 2 Recommended chromatographic column and chromatographic operating conditions
4.
2.
5 Analysis steps
Debug the instrument according to the chromatographic operating conditions listed in Table 2 to make the instrument stable
.
Weigh 0.
5 g of laboratory sample into a sample preparation bottle, add 5 mL of acetic anhydride , seal it, and place it in an oven at 150° C.
to heat at a constant temperature for 1 hour, and then cool
.
Use a 1L glass syringe or automatic injection valve to take 0.
2uL of the esterified derivative sample, inject it into the chromatograph, start the heating program, collect data and process it
.
Quantify by area normalization method
.
4.
2.
6 Result calculation
The mass fraction w i of trimethylolpropane and other components , expressed in %, is calculated according to formula (1):
Where:
A i —the area of the chromatographic peak of the esterified derivative of component i;
w 7 —The value of the mass fraction of water in the sample measured according to 4.
6
.
Take the arithmetic average of the two parallel determination results as the report result, and the absolute difference between the two parallel determination results of trimethylolpropane content is not more than 0.
05%
.