What are some common interferences in the alkalinity titration methods?

Document ID

Document ID TE101

Published Date

Published Date 08/01/2019
Question
What are some common interferences in the alkalinity titration methods?
Summary
Interferences in alkalinity titration methods
Answer
Some common interferences in alkalinity titration methods include:
  • Chlorine: Chlorine at levels above 3.5 mg/L can cause a yellow-brown color when the Bromcresol Green-Methyl Red Powder Pillow is added. To remove the interference, pretreat the sample by adding 1 drop of Sodium Thiosulfate Standard Solution, 0.1N, 100 mL MDB Product # per 100 mL sample, before adding any other reagents.
  • Color or turbidity: Color or turbidity can make it difficult to see the color change at the endpoint. Do not filter or dilute samples with color or turbidity. Use a pH meter and titrate the samples to the specified endpoints:                                                            
 
  • Soaps, oily matter, suspended solids, and precipitates: Oils or solids can collect on the pH probe and cause a slow response. Clean the probe immediately after use.