Determination Of Harmful Substance Residues In Foodstuff By Amidogen Derivation Fluorescent Spectrophotometry

Carbamate pesticides are widely used in modern growthing. Sulfa antibiotics are generaly used in breeding as medical additive of feedstuff. Melamine is a kind of harmful chemical forbidden in food and feedstuff. The irrational and illegal use of these chemicals can result in their residues in vegeto-animal products, which is harmful to human health. So, it is very necessary to develop convenient and sensitive fluorescent spectrophotometries applied to these chemicals. The assays of tsumacide sulfamethazine and melamine residues in food have been studied in this thesis.A new determination method for tsumacide residue in vegetable is developed with fluorescent spectrophotometry in the thesis. Tsumacide that is hydrolyzed for 35 min in pH10.0 boiling water can be derivatized as hyperfluorescent substance. The mass ratio of o-phthalaldehyde and tsumacide is 7.5:1 at least. A new fluorescent sepctrophotometric assay based on this principle has been developed to determine the residue trumacide in vegetable. The linear dynamic range of tsumacide is from 0.03 mg/L to 0.40 mg/L and its detection limit is 2.75μg/kg. The assay has been applied to the determination of residue tsumacide in Chinese cabbage, and the recoveries of spiked sample are 85.57%~95.32%.Sulfamethazine with a broad spectrum antibacterial activity has been widely used for prophylactic or therapeutic purpose in breedings. Sulfamethazine can be derivatized as hyperfluorescent substance with fluorescamine in pH 3.0 citric acid buffer. A new assay for sulfamethazine residue in egg is developed based on the principle. Under the optimum conditions, the detection limit of sulfamethazine is 31.43μg/kg, and the linear dynamic range is from 0.06 mg/L to 1.20 mg/L. The method has been applied to the determination of sulfamethazine residue in egg, and the recoveries of spiked sample are 89.20%~96.80%.A new fluorescent spectrophotometry has been developed for melamine residue in milk. Melamine can be derivatized as hyperfluorescent substance with o-phthalaldehyde in the borate buffer adjusted to pH 9.0. Under the optimum conditions, the detection limit of melamine is 0.008 mg/L, and the linear dynamic range is from 0.01 mg/L to 1.4 mg/L. The method has been applied to the determination of melamine residue in milk, and the recoveries of spiked sample are 78.10%~91.50%.