GB/T 4702.18-2020Chromiun metal - Determination of vanadium content - Tantalum reagent trichloromethane extraction spectrophtometry method (English PDF)

1 Scope

This part of GB/T 4702 specifies the tantalum reagent trichloromethane extraction spectrophotometric method for the determination of vanadium content.

This section applies to the determination of vanadium content in metallic chromium, the measurement range (mass fraction). 0.010% ~ 0.500%.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article

Pieces. For undated references, the latest version (including all amendments) applies to this document.

GB/T 4010 Collection and preparation of samples for chemical analysis of ferroalloys

GB/T 6682 Analytical laboratory water specifications and test methods

GB/T 7729 General Rules of Spectrophotometry for Chemical Analysis of Metallurgical Products

GB/T 8170 Numerical rounding rules and the expression and determination of limit values

GB/T 12806 Laboratory glassware single mark volumetric flask

GB/T 12808 Single-marked pipette for laboratory glassware

3 Principle

The sample is decomposed with sulfuric acid and perchloric acid. Perchloric acid oxidizes the chromium to hexavalent. The hexavalent chromium and hydrochloric acid form a chromium chloride red-brown smoke which is volatilized.

go with. In hydrochloric acid medium, the purple-red complex formed by pentavalent vanadium and tantalum reagent is extracted by chloroform, and measured at 530nm by spectrophotometer.

The amount of absorbance.

4 Reagents and materials

Unless otherwise specified, only confirmed analytical reagents are used in the analysis, and the water used meets the requirements of GB/T 6682.

Distilled water or water of equivalent purity.

5 Instruments

6 Sampling and sample preparation

Take samples according to GB/T 4010, and the samples should pass through a 1.68mm mesh.

7 Analysis steps

8 Analysis results

The analysis results are rounded off according to GB/T 8170, and two significant digits are retained.

9 tolerance

The difference between the analysis results should not be greater than the allowable difference listed in Table 2.

The difference between the two independent analysis results of the same sample is not greater than the allowable error in the laboratory, and the arithmetic mean is taken as the analysis result. in case

If the difference between the two independent analysis results is greater than the allowable error in the laboratory, follow the flow chart of the test sample analysis value acceptance procedure in Appendix A

To deal with.

10 Test report

The test report should include the following.

a) The name and address of the testing laboratory;

b) Date of release of test report;

c) The number of this part of the standard;

d) The necessary detailed description of the sample itself;

e) Analysis results;

f) The name and result of the standard sample;

g) Any abnormal characteristics in the measurement process and possible analysis results of the sample or standard sample not specified in this section

Any operation that has an impact.

Appendix A (Normative appendix)

Flowchart of the procedure for receiving the analysis value of the test sample

The flow chart of the procedure for receiving the analysis value of the test sample is shown in Figure A.1.

Figure A.1 Flow chart of the procedure for receiving the analysis value of the test sample […]