Determination of Benzylpenicillin Residue in Milk by Fluorescent Spectrophotometry with o-Phthalaldehyde Derivatization
Penicillamine is one of the hydrolyzates of benzylpenicillin under acid condition and can be derivatized as hyperfluorescent 1-thio 2-aldyl iso-indole with o-phthaldehyde.A new fluorescent spectrophotometric assay based on the derivative reaction has been developed to determine benzylpenicillin residues.Under the optimum conditions such as hydrolyzation time of 1 h,pH 10.0,derivative reagent of 40 μL and reaction time of 15 min,the linear dynamic range is 2.0-500 μgL,the detection limit is 1.3 μgL,and the average recoveries of spiked sample is 89.1%.The requirement for benzylpenicillin residue in milk in national standards can be met with the assay.