Industrial Dimethylformamide (2)

4 Test method

4.

Some test procedures specified in the test method may lead to dangerous situations, and the operator should take appropriate safety and protective measures

4.

Unless otherwise specified, only reagents confirmed to be analytically pure and grade 3 water specified in GB/T6682-2008 are used in the analysis

The standard titration solution and standard solution for impurity determination used in the analysis shall be prepared in accordance with the regulations of GB/T601-2002, GB/T602-2002, and GB/T 603-2002 unless other requirements are specified

4.

Inject 50 mL of the sample into a 100 mL stupid colorimetric tube, and observe vertically from top to bottom under sufficient light

4.

4.

Using gas chromatography, under selected working conditions, the sample is vaporized and passed through the chromatographic column to separate its components, detected by flame ionization detector (F1D), and quantified by calibration and normalization method

4.

4.

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4.
4.
3.
2 Chromatographic data processor or integrator
.

4.
4.
3.
3 Micro syringe: 1gL
.

4.
4.
4 Chromatographic column and typical operating conditions

The recommended chromatographic column and color-harmonic operating conditions in this standard are shown in Table 2
.
A typical chromatogram, and component relative retention Appendix A, Figure A.
1 and Table A.
1
.
Other color-harmonic 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.
4.
5 Analysis steps

According to the instrument manual, adjust the instrument to the operating conditions shown in Table 2, and start the measurement after the instrument is stable.
According to the chromatographic peak area of ​​each component and its calibration network, use the calibration and product to normalize and quantify
.

Refer to Appendix A, A.
3 for the determination of calibrated scintillation
.

4.
4.
6 Result calculation

The mass fractions w _i of dimethylformamide, methanol and heavy components are expressed in% and calculated according to formula (1):

Where:

A _i —the area of ​​the chromatographic peak of component i

f _i — relative correction factor of component i;

w ₂ —The value of the water mass fraction in the sample measured according to 4.
6
.

Take the arithmetic average of the two parallel determination results as the report result.
The absolute value of the two parallel determination results of dimethylformamide content is not more than 0.
05%, and the absolute difference between the two parallel determination results of methanol content is not more than 0.
0002 %, the absolute difference between the two parallel determination results of the content of non-recombination is not more than 0.
002%
.

4.
5 Determination of chromaticity

According to the provisions of GB/T 3143-1982 (2004)

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