What is the difference between the IntelliCAL™ ammonia and ammonium ion selective electrodes?

Document ID

Document ID TE3537

Published Date

Published Date 27/05/2017
Question
What is the difference between the IntelliCAL™ ammonia and ammonium ion selective electrodes?
Summary
IntelliCAL™ ammonia versus ammonium.
Answer
The IntelliCAL™ ammonia ion selective electrodes detect gaseous ammonia in solution. Because the Ionic Strength Adjustor (ISA) powder pillows (Catalog Number/Order Code 4447169) used for calibration and measurements buffer the sample pH to above 11, all ammonium ions will be converted to gaseous ammonia. As a result, the ammonia ion selective electrode does not differentiate between gaseous ammonia and ammonium ions. That being said, if the pH and temperature of the initial sample are known, one can calculate the initial fractions of gaseous ammonia and ammonium using the table 1.





The IntelliCAL™ ammonium ion selective electrodes are specific to ammonium. The ISA powder pillows (Catalog Number/Order Code 2980699) used for calibration and measurements do not buffer the sample. The sample pH range is from 0 pH to 8.5 pH. At below 8.5 pH, both gaseous ammonia and ammonium exist. The probe will not work as intented if the sample is above 8.5 pH. The electrode will only detect the ammonium in the sample and will be blind to the ammonia in the sample.