EDTA Titrimetric Determination of Sulfate and Total Hardness of Water Using Drop-Counting Micro Capillary Burette

Sulfate and total hardness of natural water were determined by EDTA micro titration in ammoniacal buffer solution with eriochrome black T as indicator.A self-made polythene microburette was used in the titration by counting the droplets used in the reaction.Volume of the droplet (ordinarity 0.01 to 0.02 mL per drop) from the microburette was calibrated by gravimetry.Amounts of titrant used in the titration were usually in the range of 50-200 droplets.Expanded uncertainty of this method was found to be 0.94% for SO2-4 determination which is equivalent to the uncertainty of the gravimetric method,while the precision is better than gravimetry.Expanded uncertainty for hardness determination was found to be 0.82%,which is also better than the macro titration method.The special features of this method were its rapidity and accuracy in analysis,less in consumption of reagent and portability.It is proved to be feasible in the worksite or field analys.s