Alternative procedures for cations

The reagent is prepared by dissolving 5g 8-hydroxyquinaldine in 12 g glacial acetic (ethanoic) acid and diluting to 100 mL with water. 

Procedure. The solution (20-30 mL) may contain 0.05-0.2 g Zr, and should possess a hydrochloric acid content of about 20 per cent by volume. Add 50 mL of 16 per cent aqueous mandelic acid solution and dilute to lOOmL. Raise the temperature slowly to 85 °C and maintain this temperature for 20 minutes. Filter off the resulting precipitate through a quantitative filter paper, wash it with a hot solution containing 2 per cent hydrochloric acid and 5 per cent mandelic acid. Ignite the filter and precipitate to the oxide in the usual manner a temperature of 900-1000 °C is satisfactory. Weigh as Zr02. 

Bromomandelic acid is a superior reagent for this determination, but is more expensive. A similar procedure to that above is employed. 

A summary of some alternative procedures for cations is given here under the headings of the various precipitating reagents used. Section references, given in parentheses, relate to the other procedure already given for that cation. 

Anthranilic acid. Cadmium ( 100 mg in 150 mL). Add 3 per cent sodium anthranilate solution to the boiling solution (neutral or weakly acid). Filter and wash the precipitate with 50mL of diluted reagent (1 20), then with ethanol. Dry at 105-110 °C and weigh as Cd(C7H602N)2 (Section 11.21). 

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