Determination of acrylonitrile content below 3mg/kg Headspace Gas Chromatography (Ammonia Phosphorus Detector) (2)

A.

This chapter corresponds to Chapter 5 of the standard.

A.

A.

Weigh about 50ing of propionitrile (A.

A.

Weigh 1.

When preparing the calibration solution, pipette a certain volume of the above mother liquor, and then dilute it with PC.

A.

Weigh 0.

During the process of injecting the acrylonitrile calibration solution into the sample bottle, the syringe needle should be immersed in the PC or internal standard solution to prevent the acrylonitrile calibration solution from being brought out when the needle is pulled out from the rubber pad

A.

According to the process of A.

A.

Weigh 0.

A.

Use a pipette to pipette 5mL PC (A.
2.
1) or the internal standard solution prepared according to A.
5.
1, put it into a 25mL or 50mL sample bottle (A.
3.
2), and close the cap
.

A.
5.
7 Determination

Place the sample solution (see A.
5.
5), reference sample solution for calibration (see A.
5.
3), zero content sample solution (see A.
5.
4) and blank solution (A.
5.
6) at 70°C for 16 hours (automatic sampling When placed in a constant temperature bath, manual injection is placed in a constant temperature oven), A.
3.
1 gives the recommended conditions for white dynamic injection
.
After the condition is adjusted: accurately extract 1 mL of the gas phase part of the sample from the sample bottle through the rubber pad, and inject the sample into the gas chromatograph
.
In manual sampling, use a gas injector (A.
3.
5) to draw a gas sample, and then inject it into the gas chromatograph
.
As the sensitivity of the thermionic detector decreases over time, when formulating a calibration curve or calibration value, record the zero-content sample solution (see A.
5.
4) before and after every 5-10 reference samples (see A.
5.
3).
) And blank solution (A.
5.
6) measurement results
.

A.
5.
8 Evaluation of gas chromatographic peaks

In this method, the peak height (in mm) is used instead of the peak area
.