In Method 9060A, what is the purpose of homogenizing a water sample with a blender (Section 7.1)? Is there any flexibility with this requirement?
Method 9060A can be used to analyze for five different types of carbon, listed in Section 2.2. It is used for groundwater, surface and saline waters, and domestic and industrial wastes. Consequently, samples may include silts, cellulose fibers, or other particulate organic matter, for which homogenization will provide more representative sampling for your analytical subsample. While homogenizing clean waters with no particulates may not be needed to get a representative sample, the homogenization step was included here so the method could cover the other types of samples as well. Further, the method authors did not create a homogenization exception for clean-looking waters. Since the method is on the Method Defined Parameter (MDP) list in the SW-846 manual, it must be followed exactly as prescribed. There is no flexibility on MDPs in a regulatory situation, however you can petition your regulatory agency to not have to homogenize in the case of clean water samples with no particulates if the samples are being done in a non-regulatory situation.