High-performance liquid chromatographic assay of erythromycin from biological matrix using electrochemical or ultraviolet detection

Two chromatographic methods were developed for the determination of erythro mycin A (EA) residues in animal tissues (muscle, liver, kidney and fat of c attle, pigs and poultry) and cow's milk. In addition to a more traditional method using electrochemical detection, we developed an original alternativ e method based on UV detection at 236 nm, by pretreating to create a chromo phore in the molecule. An internal standard was used with both methods to c heck the variability of the analytical system. Analysis times and performan ce were compared. The recovery of EA from various matrices was greater than 95%. For both methods the quantification limit for EA was 0.25 mu g ml(-1) for plasma, 0.025 mu g g(-1) for milk and 0.125 mu g g(-1) for the other b iological matrices. The methods can be used to check for EA residues in the se matrices; in fact, the statutory maximum residue limits (MRLs) of EA are 0.4 mu g g(-1) in muscle, kidney, liver and fat of beef cattle, sheep, pig s and poultry, and 0.04 mu g g(-1) in cow's and sheep's milk.