| Summary: | 碩士 === 中原大學 === 化學研究所 === 100 === Abamectin (ABA) is a kind of herbicide and is seriously harmful to human health. After feeding the cattle by abamectin added forage, abamectin residues will remain in the body, which will further endanger the health of human. Ivermectin are antiparasitic agents. Treat the cattle with Ivermectin will also cause residue that indirectly endangers the safety of human. Therefore, a fast, precise, accurate, and efficient method for monitoring the two kinds of residues must be established to avoid their occurrence.
In this study, on-line coupling of a solid-phase extraction column to the liquid chromatography electrospray ionization ion-trap tandem mass spectrometer was developed by the column-switching technique to perform the on-line matrix reduction of milk samples and the inspection of Abamectin and Ivermectin residues in milk. The results will be compared with UV dection. The detection of the ion-trap mass spectrometer uses multiple-reaction monitoring secondary mass spectrometry in positive ion mode. The concentration range of the matrix-enhanced external standard calibration curve of the secondary mass spectrometry for the two kinds of drug was 0-15 ng/mL which exhibits very good linearity with R2 equaling to 0.9938 (Abamectin) and 0.9990 (Ivermectin). The limit of detection (LOD) and quantification (LOQ) were 0.67 ng/mL and 2.23 ng/mL for Abamection, respectively, and 0.63 ng/mL and 2.11 ng/mL for Ivermectin, respectively.
Quantification of Abamectin and Ivermectin in milk samples of five different brands by the standard addition method indicates that two brands of milk samples contain trace amounts of Abamectin (0.65 and 0.57 ng/mL) and Ivermectin (0.79 and 1.04 ng/mL), both of which close to the detection limit. Abamectin and Ivermectin in the milk samples of the other three brands are all well below the LOD and close to zero ng/mL. Overall, the content of Abamectin and Ivermectin in the five brands of milk are all lower than the requlated maximum residue limit (10 ppb). The analytical accuracy of the the two brands of milk samples was 84% and 82% for Abamectin, respectively, and 82% and 88% for Ivermectin, respectively; the precisions were 8.0% and 7.3% for Abamectin, respectively, and 4.8% and 9.7% for Ivermectin, respectively. The analysis time for one sample was 10 min. Overall, the developed method is fast, sensitive, precise, and accurate and is successfully applied for the Abamectin and Ivermectin residue analysis of milk samples.
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