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In order to find a more accurate and easier method for gypsum determination, the aceton and resin_H+ methods were carried out on 9 samples with different quality and quantity of salts selected from 5 profiles located in Eshtehard region (Iran).
The resin_H+ method is theoretically based on replacement of 11+ ions from resin by Ca ions from-soluble CaSO4 and determination of released acidity.
The results of these methods showed that the value obtained by resin_H+method is always higher than aceton method.This difference ranges between 1.87 to 23.91% for different samples. The considerably higher values of the resin_H+ method could be related mainly to the greater efficiency of the method, to the higher solubility of gypsum in the acidic environment of the resin and fewer origin of errors (elmination of washing treatments).
Fluctuation of the differences between the results of two methods is probably due to variation of solubility of gypsum in presence of different salts.Therefor, the minimum difference is observed on the samples with chloride type of salinity, medium difference on the samples with sulfate—chloride type and maximum difference on the samples with chloride—sulfate type of salinity.