Antibiotic residues must first be extracted (or separated from manure), then purified, so that they can be accurately measured. Just as there is no standard approach to sample manure for antibiotic residues, there is also no standard method for extracting antibiotic residues from manures. The challenge to developing such standards is that depending on the target antibiotic and the exact composition of the manure, the extraction approaches could vary widely. The approach developed by our collaborators[1] was optimized to target multiple classes of antibiotics from dairy manure is outlined below.