Determination of cyclohexanone oxime in industrial caprolactam

1 Scope

This part of GB/T 13255 specifies the method for determination of cyclohexanone oxime content in industrial caprolactam in the ferric hydroxamate spectrophotometric method

2 Normative references

The clauses in the following documents become clauses of this part through the reference of this part of GB/T13255

GB/T 66822008 Analytical laboratory water specifications and test methods (ISO3696:1987, MOD)

GB/T 8170 Numerical Rounding Rules and the Expression and Judgment of Limit Values

3 Principles of the method

Hydroxylamine and formaldehyde generated when cyclohexanone oxime is hydrolyzed in an acidic medium can generate formyl hydroxamic acid (also known as formyl hydroxamic acid) under the condition of adding ammonium persulfate, and formyl hydroxamic acid can be combined with ferric iron The ion generates a red complex, and the absorbance is measured with a spectrophotometer at the maximum absorption wavelength of 500nm

4 Reagents

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

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5 Instruments

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6 Analysis steps

6.

Use a graduated pipette to accurately pipette 0.

Use the cyclohexanone oxime content as the abscissa and the corresponding absorbance as the ordinate to draw a working curve

6.
2 Determination

Weigh about 10g of laboratory sample, accurate to 0.
1g, place it in a 100mL volumetric flask, add 50mL of water to dissolve it, and then add 2mL of sulfuric acid solution.
The following operations start from "5mL formaldehyde solution.
.
.
" as described in 6.
1.
The same measurement was performed until "measurement of absorbance"
.

Find out the content of cyclohexanone oxime in the sample solution on the working curve according to the measured absorbance
.

7 Result calculation

The cyclohexanone oxime content z expressed in mg/kg is calculated according to formula (1):

Where:

m1——The value of the cyclohexanone oxime content in the sample solution found on the working curve, in milligrams (mg);

m——The value of the mass of the sample, in grams (g)
.

The difference between the two parallel determination results is not more than 5mg/kg, and the arithmetic mean is the determination result
.

The result should be expressed as an integer after rounding up according to GB/T8170
.

8 reports

The report should include the following:

a) All information about the sample, such as sample name, batch number, sampling location, sampling date, sampling time, etc.
;

b) Code of this part;

c) Analysis results and presentation methods;

d) Details and descriptions of any abnormal phenomena observed in the measurement;

e) The name of the analyst and the date of analysis, etc.
;

f) Any description of the operation or test conditions not included in the wood part
.

Related Links: Determination of Iron Content of Caprolactam for Industrial Use