NO2/NO3 in a metals lab?

[Bigbear]

We just purchased a Dionix IC for anions. It's lots more sensitive than the colorimetric method we currently use. We are getting a nitrate peak in all our blanks at our action limit! We run a lot of metals in drinking water so there is a lot of nitric acid used.
We have put no2/no3 test strips throughout the lab which come up positive.
Any ideas how to deal with this without moving the system?

[DR]

Switch to RO polished water (or am I missing something)?

[tom jupille]

This may sound like telling the cobbler's children to get new shoes, but check your hoods and ventilation; you might be picking it up from the atmosphere.

[Bigbear]

An update on this problem. It seems that the contamination was coming from our DI water. We sanitized the unit and replaced membranes and got rid of the nitrate peak.

[tom jupille]

Thanks for the update. It's always nice to know the end result!