Frequent Questions

Can a laboratory switch the purge gas for VOCs from helium to nitrogen for compliance work under the SDWA (Methods 524.2 and 524.4)

There is no provision within Method 524.2 that allows for alternate purge gases. But, EPA Method 524.4 is an approved method; it was approved in the last expedited methods approval action (78 FR 32558 published Friday, May 13, 2013). However, that States have the authority to restrict the methods that they will permit to be used for compliance monitoring. So it’s possible that a state has not approved the use of Method 524.4.

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