The following are reminders of the interference check requirements for Method 7E and all methods that reference the Method 7E procedures:

1.  Interference check data for each analyzer must be available on-site and included in each test report.

2.  The interference check must be done BOTH with the interferent(s) introduced alone, AND the interferent(s) introduced with the pollutant of interest.  Refer to Section 8.2.7(1) of Method 7E for additional details.

3.  The method(s) allow for the interference check to be done on a representative instrument of the same make and model, or have this data provided by the instrument manufacturer.  However, in order to be valid, the representative analyzer must be an instrument configured the same as the analyzer used for testing.  For example, if the analyzer used for testing includes additional components to remove an interferent (such as an ammonia scrubber on a NOx analyzer), the representative analyzer must also have these components during the interference check.  In the example listed, the ammonia scrubber is considered to be part of the gas analyzer.