When is it appropriate to record the pH on the label of hazardous chemical waste? A rule of thumb is that EHS would like to see a pH recorded if water is present in the waste, and particularly if there are substances present known to raise or lower the pH such as acids and bases. We need to know this because we use the information to help make decisions on safe handling and disposal of the waste. EHS understands that other chemicals may also be present that interfere with measurement of pH and there will be exceptions to this rule of thumb. If the pH is not recorded for this reason or others, and the waste pickup team has questions about that choice, they’ll discuss it with the lab.
The pH of a liquid may be tested by using pH paper or a pH meter. pH paper is available from Biochem and Chem Stores on campus or most scientific supply companies. To test waste with pH paper, wearing appropriate PPE, carefully open the waste container in a fume hood. Dip the strip into the liquid and compare the color change to the scale on the packaging.
Alternatively, the waste may be tested for pH before it is placed in the waste container. Contact Tim Weber at 319-335-4626 with questions about hazardous chemical waste.