Industrial Acetic Anhydride (Appendix C)

Appendix C

(Standard appendix)

Determination of iron content-atomic absorption spectrometry

C1 method summary

After the sample is evaporated, it is prepared into a solution of appropriate concentration, sprayed in an air-acetylene flame, with an iron hollow cathode lamp as the light source, and the absorbance of the sample is measured at a wavelength of 248.

C2 reagents and solutions

The water used in this method refers to the secondary water specified in GB/T6682

C2.

C2.

C2.

C2.

C2.

C2.

Weigh 1g of iron, accurate to 0.

C2.

Draw 1.

C3 instrument

C3.

C3.

The characteristic concentration of iron in the solution consistent with the matrix of the test sample solution should not be greater than 0.

C3.

Under the given test conditions, the standard samples with absorbance in the range of 0.

C3.
2 iron hollow cathode lamp
.

C3.
3 flame atomizer
.

C3.
4 Gas: Acetylene
.

C3.
5 oxidant gas: air
.

C3.
6 water bath
.

C3.
7 evaporation m: 150mL, round bottom porcelain or glass
.

C3.
8 pipette: 100mL
.

C3.
9 volumetric flask: 25mL
.

C4 analysis steps

C4.
1 Preparation of sample

Pipette 100mL sample in a porcelain or glass Yanfa dish, evaporate to dryness on a boiling water bath, dissolve the residue with 2mL hydrochloric acid solution, transfer it into a 25mL volumetric flask, and dilute to the mark
.

C4.
2 Drawing of working curve

C4.
2.
1 Preparation of calibration solution

Pipette 0～10.
0mL iron standard solution into 4～5 25mL volumetric flasks, add 2mL hydrochloric acid solution, and dilute to the mark
.

C4.
2.
2 Determination of the absorbance of the calibration solution

Under the given instrument test conditions, after the instrument is stabilized and adjusted to zero with water, measure the absorbance of the calibration solution respectively
.

C4.
2.
3 Drawing of working curve

Use the concentration of the iron calibration solution as the abscissa, and subtract the absorbance of the reagent blank as the ordinate to draw a working curve
.
Or draw the curve directly by the data processing system
.

If a data processing system is used, the working curve can be carried out when the sample is measured
.

C4.
3 Determination of sample

Measure according to the provisions of C4.
2.
2
.
Check the concentration value from the working curve (or read the concentration value directly)
.

Expression of C5 analysis results

C5.
1 The iron content expressed in mass percentage is the maximum X ₁ , calculated according to formula (Cl):

In the formula: C—the concentration obtained from the working curve, ug/mL;

V ₁ —The volume of the sample solution during measurement, mL;

V——The volume of the sample, mL;

ρ—The density of the sample at 20°C, g/cm3
.

Take the arithmetic mean of the two parallel determination results as the determination result, and the difference between the two parallel determination results shall not exceed 0.
00001%
.