The determination of sulphur in nickel

The sulphur content of nickel ranges from a few ug/g up to some 10 pg/g. Nickel alloys contain a few 100 pg/g of sulphur. Again, combustion and dissolution methods are applied. 

According to Analysis of Metals (1) a method similar to that for copper can be used. Two g of chips are combusted at 1400 to lASO C in an oxygen stream in a tube furnace. The combustion boat is filled with the nickel chips, which are then covered by 2 g of copper chips. The determination of sulphur dioxide is carried out by iodometric titration. 

This method is said to allow the determination of sulphur amounts above 50 g/g. Its accuracy is 10 % at the 100 pig/g level and 5 % at the 1 mg/g level. 

For the analysis of nickel alloys Burke (3) recommends the combustion method with addition of vanadium pentoxide, which is described in section 1.1.1. The sulphur yield for different alloys is 80 to 100 % for contents between 20 and 280 p g/g. 

Barabas and Kaminski (7) mention the use of strips of tinned copper sheet as combustion flux. 

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The same problems exist thus with the determination of sulphur in nickel as with sulphur in copper. Also here, the dissolution methods are the more accurate ones. In any case, the combustion methods need reference materials with known sulphur contents to establish a reliable calibration. 

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