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5 Test method
5.
Industrial cyclohexanol is a flammable product, so pay attention to safety during analysis
5.
Unless otherwise specified, only reagents confirmed to be analytically pure and grade 3 water specified in GB/T6682-2008 are used in the analysis
5.
5.
Using gas chromatography, under selected working conditions, the sample is vaporized and passed through the chromatographic column, so that the components are separated, detected by a hydrogen flame ionization detector, corrected for water content, and calculated by area normalization method.
5.
5.
5.
5.
5.
5.
5.
5.
5.
5.
3.
4 Chromatographic analysis conditions
The recommended chromatographic columns and typical chromatographic analysis conditions are shown in Table 2
.
The typical chromatogram of the capillary column is shown in Appendix A, Figure A.
1, and the relative retention value of each component is shown in Appendix A, Table A.
1
.
Other chromatographic columns and chromatographic operating conditions that can achieve the same degree of separation can be used
.
Table 2 Recommended chromatographic columns and typical chromatographic analysis conditions
5.
3.
5 Analysis steps
Adjust the instrument according to the chromatographic operating conditions.
After the baseline is stable, use a micro-syringe to inject the sample, measure the area of each peak, and calibrate the water content and calculate according to the area normalization method
.
5.
3.
6 Result calculation
The mass fraction w i of each tested component , the value is expressed in %, respectively calculated according to formula (1):
Where:
A i —the peak area of the measured component i;
w Water —The value of the mass fraction of water measured according to 5.
5;
∑A i — the sum of the corrected peak areas of each component
.
Take the arithmetic average of the two parallel determination results as the determination result
.
The absolute difference between the two parallel determination results of cyclohexanol content is not more than 0.
2%; when the mass fraction of impurities is ≥0.
5%, the absolute difference between the two parallel determination results is not more than 5% of the arithmetic mean; the mass fraction of impurities is < At 0.
5%, the absolute difference between the two parallel determination results is not more than 10% of the arithmetic mean
.
5.
4 Determination of chromaticity
According to the provisions of GB/T3143-1982
.
5.
5 Determination of water content
According to the provisions of GB/T6283-2008 or GB/T2366-2008
.
The test method specified in GB/T6283-2008 is the arbitration law
.
When measuring samples containing cyclohexanone impurities according to the method specified in GB/T6283-2008 , Karl Fischer reagent uses special reagents for aldehydes and ketones
.
Take the arithmetic average of the two parallel determination results as the determination result.
When the determination is performed according to the provisions of GB/T6283-2008, the absolute difference between the two parallel determination results shall not be greater than 25% of the arithmetic average; according to GB/T2366-2008 When the determination is carried out according to the regulations, the absolute difference between the two parallel determination results shall not be greater than 35% of the arithmetic mean
.