Method 1664 may be used as described in the analytical method with the restrictions detailed in the EPA letter of February 29, 1996

EXCEPT for:

1. Petroleum contaminated sites or where the petroleum suite of parameters are being analyzed, or
2. Programs that specifically cite an alternative method.

FL-PRO must be used for State-related petroleum contaminated sites.

The EPA letter regarding this issue is a PDF file, so you may need the Adobe Acrobat reader if you download the file.