Urine pH determination

Reaction of acid-base indicators used in the examination of urine pH

The indicator zone for pH contains a mixture of selected acid-base indicators. Most use two acid-base indicators – methyl red and bromothymol blue, or phenolphthalein. This ensures a pH reading in the 5-9 range by changing color from orange (acidic pH) to green to blue (alkaline pH). The reading is possible with an accuracy of 0.5.