Determination of purity of methyl chloride products for industrial use—gas chromatography (2)

7 Analysis steps

7.

7.

Weigh the mass of a 100mL screw-top bottle with septum to the nearest 0.

Mass m impurity gas component i _i , values in grams (g), calculated according to formula (1):

Where:

V _i ——The gas volume of the added impurity centimetre i, in milliliters (mL);

M _i ——The molar mass of the added impurity component i, in grams (g);

24450——The volume of 1 mole of gas at 25°C and 101.

M mass of the liquid of impurity components i _i .

mi=p _i V _i .

Where:

V _i ——the liquid volume of added impurity component i, in milliliters (mL);

p _i ——The density of the added impurity component i, in grams per milliliter (g/mL)

7.

The mass fraction w _i of impurity component i in the calibration standard sample , the value is expressed in %, calculated according to formula (3):

Where:

m _i ——the mass of impurity component i in the calibration standard sample, in grams (g);

m——The mass of the wood bottom sample in the calibration standard sample, in grams (g)

7.

Take a quantitative standard sample for calibration, measure it according to the selected chromatographic operating conditions, and measure the corresponding methyl chloride background sample at the same time

Where:

w _i ——the mass fraction (%) of impurity component i in the calibration standard sample;

△A _i ——the impurity component in the calibration standard sample: the difference between the peak area of ​​the peak area and the peak area of ​​the impurity component _i in the corresponding background sample;

wR——The mass fraction of reference substance R (%);

R AR-- peak area of reference

7.

7.

7.
2 Determination of samples

Take a liquid sample for determination according to the selected chromatographic operating conditions
.

8 Result calculation

The content of methyl chloride is calculated as the mass fraction w ₁ and the value is expressed as %, calculated according to formula (5):

Where

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

f _i ——The relative mass correction factor of component i;

wH ₂ O——The mass fraction of water in the methyl chloride sample
.

Take the arithmetic mean of the two parallel determination results as the determination result
.

The absolute difference between the two parallel determination results of the main content is not more than 0.
02%
.

When the mass fraction of impurities is less than or equal to 0.
01%, the absolute difference between the two parallel determination results shall not be greater than 20% of the average of the two parallel determination results
.

When the mass fraction of impurities is greater than 0.
01%, the absolute difference between the two parallel determination results shall not be greater than 10% of the average value of the two parallel determination results
.

Related Links: Determination of Purity of Methyl Chloride Products for Industrial Use-Gas Chromatography (1)