Why is the method I’m looking for not in SW-846?
Once a method has been updated, previous versions are moved to the EPA Archive and can be found there by searching for the method number. For example, when Method 8000D was published in SW-846, Method 8000C was moved to the Archive.
If the method you’re looking for has a number with the format XXX or XXX.X (e.g., Method 624 or Method 200.8), it is a water method promulgated by the EPA Office of Water either for the Clean Water Act (CWA) or for the Safe Drinking Water Act (SDWA). These methods can be found on the Clean Water Act Analytical Methods website and the Safe Drinking Water Act Analytical Methods website.
If you are looking for a 1600 series method (method 1600-1682), it is a Clean Water Act method and is not part of SW-846.
Additional environmental monitoring methods can be found on the EPA Environmental Measurement website.