# Insights on Stereoselective Residue and Degradation of Spirotetramat Enantiomers on Tubifex of the Qinghai Plateau

## TL;DR

This study developed a method to measure spirotetramat enantiomers in tubifex and found their degradation rates and residue levels.

## Contribution

A novel HPLC-MS/MS method was developed for enantioselective quantification of spirotetramat in tubifex.

## Key findings

- The method achieved recovery rates of 81–114% with relative standard deviations under 7%.
- Half-lives of spirotetramat enantiomers in tubifex ranged from 3.81 to 10.58 days.
- Residues after 14 days were below 0.03 mg/kg, supporting safe usage recommendations.

## Abstract

This study established an HPLC-MS/MS method to quantify the enantiomers of spirotetramat in tubifex. To assess the accuracy and precision of the approach, recovery tests were conducted for insecticide. For all enantiomers, the limits of detection were 0.003 mg/kg. The quantization limits were 0.01 mg/kg. Spirotetramat enantiomers recovery rates in tubifex were found to be between 81 and 114%, with relative standard deviations being less than 7%. The half-lives of spirotetramat enantiomers in tubifex were 3.81–10.58 d, respectively. The 22.4% spirotetramat suspension was sprayed on tubifex three times at a low dosage (high dosage advised). After 14 days after harvesting, the terminal residues of spirotetramat enantiomers in the tubifex were less than 0.03 mg/kg. The findings offer a quantitative foundation for setting China’s maximum residue limits as well as a recommendation for the safe and responsible usage of spirotetramat enantiomers in tubifex.