Is the Hach Ammonia Ion Selective Electrode (ISE) method EPA compliant for reporting?

Document ID

Document ID TE124

Version

Version 3.0

Status

Status Published

Published Date

Published Date 25/01/2018
Question
Is the Hach Ammonia Ion Selective Electrode (ISE) method EPA compliant for reporting?
Summary
Using an ammonia ISE probe for reporting to United States Evironmental Protection Agency (USEPA)
Answer
The Nitrogen-Ammonia Ion Selective Electrode (ISE) Method 10001 and 10002 has equivalent status for United States Evironmental Protection Agency (USEPA) wastewater reporting. For wastewater applications, the ammonia (ISE) methods reference Standard Method 4500-NH3-D and 4500-NH3-E / USEPA method 350.3 / ASTM D1426-98 for compliance but are not approved or accepted.  These designations mean that you must check with your local regulator before reporting results obtained using this probe.

Provided below are details for USEPA approval criteria and ISE best practices:

-Use pH/ion meter and electrode with hydrophobic, gas-sensing membrane separating sample from internal ammonium chloride electrolyte solution.
-Internal glass pH sensor will measure the internal solution's change in pH.
-Fixed level of chloride in internal solution is sensed by internal chloride reference electrode.
-Use of Ammonia Ionic Strength Adjustor (ISA) to pH adjust sample.
-Samples and calibration standards are at the same temperatures.
-Method also states that a longer stabilization time, up to 5-10 minutes, for concentrations below 1 mg/L NH3-N.SensION, sensION+, and IntelliCAL Nitrogen-Ammonia (ISE) probes meet these requirements.