GB/T 4698.5-2017Methods for chemical analysis of titanium sponge, titanium and titanium alloys - Part 5: Determination of molybdenum content - Thiocyanate spectrophotometry and inductively coupled plasma atomic emission spectrometry (English PDF)

2.1 Method summary

The sample is dissolved in sulfuric acid. In sulfuric acid medium, molybdenum (V) is reduced to molybdenum (V) by thiourea using copper (II) as catalyst.

The cyanate generates an orange-red complex and its absorbance was measured at a spectrophotometer wavelength of 465 nm.

2.2 Reagents

Unless otherwise stated, only reagents identified as analytical grade and laboratory grade II water were used in the analysis.

2.2.1

Nitric acid (p = 1.42 g/mL).

2.2.2

Sulfuric acid (1 1).

2.2.3

potassium thiocyanate solution (500g/L).

2.2.4

copper sulfate solution (20g/L).

2.2.5

thiourea solution (100g/L).

2.2.6

titanium matrix solution Weigh 0.500g titanium metal (wTi >= 99.95%, wMo < 0.001%) in a 150mL beaker, the following press

2.5.4.1. 1 mL of this solution contains 2 mg titanium.

2.2.7

molybdenum standard storage solution Weigh 0.5000g metal molybdenum (wMo >= 99.95%) in 400mL beaker, add 50mL sulfuric acid (2.2.2), 30mL of nitric acid (2.2.1), covered with a watch glass, heated to completely dissolve and continue heating to take sulfuric acid smoke, cooled, add 50mL

Water, heated to dissolve salts, cooled, transferred to 500mL volumetric flask, diluted with water to the mark, mix well. This solution 1 mL contains 1.0 mg molybdenum.

2.2.8

molybdenum standard solution Pipette 10.00mL molybdenum standard stock solution (2.2.7) in 100mL volumetric flask, diluted with water to the mark, mixed uniform. This solution 1 mL contains 100 µg molybdenum.

2.3 Instruments

Spectrophotometer.

2.4 sample

In accordance with the promulgated sponge titanium, titanium and titanium alloy take sample preparation standards.