Experimental teaching design of instrument analysis for undergraduate study： detection of bifenthrin pesticide residues in tea by response surface methodology-optimized QuEChERS combined with gas chromatography-mass spectrometry

This paper designs an experimental scheme to meet the undergraduate experimental teaching requirements of the Pharmaceutical Engineering major. The content focuses on the detection of bifenthrin pesticide residue in tea by QuEChERS-GC-MS. The experimental contents include sample pretreatment， single-factor screening and response surface methodology optimization of QuEChERS experimental conditions， establishment of a GC-MS analysis method， determination of bifenthrin pesticide residues in tea samples， and experimental data processing. It aims to cultivate students’ ability to comprehensively apply modern analytical techniques to solve practical problems. Through this experiment， students can master the basic principles and operational skills of GC-MS instruments and equipment， and understand the complete process of pesticide residue analysis in real samples， and recognize the importance of sample pretreatment for the analysis of trace components in complex systems. Under the QuEChERS experimental conditions screened in the single-factor experiment， the recovery rate of bifenthrin in the tea samples was 85.9%. Under the QuEChERS experimental conditions optimized by the response surface methodology， the recovery rate of bifenthrin in tea samples can reach 90.33%. Among the 38 tea samples， bifenthrin was detected in 12 samples， with the maximum detected value of 0.911 mg/kg. None of them exceeded the maximum residue limit of bifenthrin in tea stipulated in the National Food Safety Standard GB 2763-2021. This teaching design involves learning relevant content before the experiment， training operational skills during the experiment， and conducting data analysis after the experiment. It can not only stimulate students’ interest in learning， but also cultivate their rigorous scientific thinking. It enables students to proactively face problems， actively analyze them and try to solve them throughout the entire learning process.