Industrial Acetic Anhydride (Appendix A)

Appendix A

(Standard appendix)

Determination of chromaticity-spectrophotometry

A1 method summary

The yellowness index can quantitatively describe the color of the sample.

Note: The yellowness is the difference between the yellowness index of the standard colorimetric solution and water

A2 Reagents and solutions

Platinum-cobalt standard colorimetric solution: prepared according to GB/T3143

Prepare standard colorimetric fluids with no less than 10 color numbers in the range of 0-30 platinum-diamond color numbers

A3 instrument

A3.

Meet the requirements of 6.

A3.

Meet the requirements of 7.

A4 analysis step

A4.

A4.

Put the empty dish into the reference cell, put the water into the sample cell, and adjust the transmittance of the instrument to 100%.

A4.

A4.

Take air as a reference, and measure the transmittance of water and standard colorimetric solution at intervals of 10nm in the wavelength range of 380~780nm

A4.

The yellowness index is calculated according to formula (A1):

In the formula: Y _i — the yellowness index of the tested substance;

X, Y, Z-the two stimulus values ​​of the tested substance
.

The tristimulus value of the tested substance is calculated according to formula (A2), (A3), (A4):

In the formula: K—naturalization coefficient,

S(λ)—The relative spectral power distribution of the standard light source (illumination body);

x(λ), y(λ), z(λ)——chromaticity function in XYZ chromaticity system;

τ(λ)—the transmittance of the measured substance;

△λ—wavelength interval
.

For the weighting coefficients S(λ)x(λ), S(λ)y(λ), S(λ)z(A), please refer to the C illuminator data in Table 2.
1 of GB/T3979-1997
.

A4.
1.
2.
3 Calculation of yellowing degree of standard colorimetric fluid

The yellowing degree is calculated according to formula (A5):

△Y _i =Y _i -Y ₀ .
.
.
.
.
.
.
.
(A5)

In the formula: △Y _i -the yellowing degree of the standard colorimetric fluid;

Y _i —yellowness index of standard colorimetric fluid;

Y ₀ —The yellowness index of water
.

Use the platinum-cobalt color number of the standard colorimetric solution as the abscissa and the corresponding yellowness as the ordinate to draw the standard curve
.

A4.
2 Colorimeter analysis steps

Measure the tristimulus value of the substance to be tested according to the specifications of the instrument, and perform the others according to the provisions of A4.
1.
2
.

A4.
3 Determination of samples

Measure and calculate the yellowing degree of the sample according to the above regulations (A4.
1 or A4.
2)
.

A4.
4 Expression of analysis results

According to the yellowing degree of the sample, the color number of the sample can be found on the standard curve
.

Take the arithmetic average of the two parallel determination results as the determination result, and the difference between the two parallel determination results shall not be greater than a platinum-diamond color number
.