Concentration by trace precipitation

Quartz or porcelain dish for evaporation, volume at least 1 litre Beakers of various sizes Porcelain crucible 

For concentration by trace precipitation or coprecipitation the entire contents of a flask must be used. In general, a volume of 10 litres is 

Treat the precipitates (sediments) in the sample flask with 25 % HCl and wash into a beaker together with the residue which is insoluble in acid. 

Evaporate the principal solution (see above) to a volume of about 0.5 - 1 litre and carefully acidify with this acid solution. Filter the acid 

Incinerate the insoluble residue collected on the filter. Grind the 

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Evaporate the chloroform extracts almost to dryness over a water bath, wash over to a porcelain crucible, bring to dryness on a sand bath and incinerate in a muffle furnace at 330 C. Proceed with spectrographic analysis as described under "Concentration by trace precipitation". 

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