HI 38013 Phenolphthalein and Total Alkalinity Test Kit Product Description: In this case the phenolphthalein alkalinity is determined by neutralizing the sample to a pH of 8.3 using a dilute sulfuric acid solution and a phenolphthalein indicator. Since bicarbonate ions can be converted to carbonic acid with additional sulfuric acid, the phenolphthalein alkalinity measures total hydroxide ions, but only half ... Read More »