500 ml of test solution containing 10 mg u00b7 l u2212 1 of antiscalant dry basis 240 mg u00b7 l u2212 1 of ca 2 and 732 mg u00b7 l u2212 1 of hco 3 u2212 was prepared by adding calculated volume antiscalant stock solution calcium stock solution bicarbonate stock solution and double distilled water respectively to a glass bottle the ph of each test solution was adjusted to 9 0 by using borate buffer solution the bottles were incubated in a water bath for 18 hour at 80 u00b0 c after cooling an aliquot quantity was filtered through 0 22 u03bcm filter paper and then the calcium concentration in the filtrate was measured using the standard edta titration method meanwhile the control test in the absence of antiscalant was conducted static inhibition efficiency test for calcium sulfate was performed similar to the static calcium carbonate inhibition efficiency the 500 ml of test solution contained 5 mg u00b7 l u2212 1 of antiscalant dry basis 2500 mg u00b7 l u2212 1 of ca 2 and 7350 mg u00b7 l u2212 1 of so 4 2 u2212 it was adjusted to 7 00 u00b1 0 1 by the addition of hcl and or naoh solution 10 the bottles were incubated in a water bath for 18 hour at 80.