Is filtration of samples allowed when running Lachat in-line distillation methods for ammonia?

Document ID

Document ID TE6653

Published Date

Published Date 27/05/2017
Question
Is filtration of samples allowed when running Lachat in-line distillation methods for ammonia?
Summary
Filtration of samples for inline ammonia
 
Answer
EPA (NPDES) is getting questions lately about in-line ammonia methods with gas diffusion and what to do about particulates. Specifically, is filtration allowed prior to analysis.

In the same manner that a comparison to prove an off line distillation is not needed, labs will need to do a comparison with samples distilled off-line, samples filtered and distilled off-line, and the values obtained for samples run using this type of method following filtration.

Particles can bind all kinds of things and this ion is one that could potentially bind. Therefore, regulators are likely to require a comparison be made to verify results are similar.