GB/T 4325.13-2013Methods for chemical analysis of molybdenum - Part 13: Determination of calcium content - Flame atomic absorption spectrometry (English PDF)

1 Scope

GB/T 4325 This section specifies the method for determination of molybdenum of calcium.

This section applies to molybdenum powder, molybdenum, molybdenum trioxide, ammonium molybdate determination of calcium. Measurement range. 0.0005% to 0.030%.

2 Method summary

Sample decomposition of hydrogen peroxide, citric acid, hydrochloric acid medium, using standard addition method using air - acetylene flame atomic absorption of light

Spectrometer to measure calcium absorbance at the wavelength of 422.7nm, and calculate the amount of calcium.

3 Reagents

Unless otherwise indicated, this part of the reagents used are in line with national standards or industry standard analytical reagent, the water is deionized water.

4 Instrument

Atomic absorption spectrometer, with a calcium hollow cathode lamp.

Under optimum working conditions for those who can reach the following indicators can be used.

--- Characteristic concentration. measurement solution with the matrix consistent solution, characterized in calcium concentration should not exceed 0.05µg/mL;

--- Precision. standard solution with the highest concentration of 10 times the absorbance measurements, the standard deviation should not exceed 1.5% of the average absorbance;

With the lowest concentration of standard solution (not "zero" concentration of the standard) measuring the absorbance of 10 times, the standard deviation should not exceed the maximum

The average concentration of 0.5% absorbance;

--- Linear curve. the curve according to concentration, divided into five sections, the difference between the absorbance of the absorbance difference between the highest and the lowest segment segment

Ratio should not be less than 0.7.

5 Sample

Molybdenum should smash through the 0.75mm standard sieve.