Determination of Pymetrozine in Rat Tissues by HPLC-MS/MS

In order to study the toxicokinetic characteristics of pyridoxine in rats at different doses, SD rats were used as the research object, and single-time exposure was carried out by oral gavage. Animal tissue samples were collected at different time points. After the samples were treated with protein precipitation, the pyridoxine prototype was detected by high performance liquid chromatograpy-tandem mass spectrometry (HPLC-MS/MS) method with imidacloprid as internal standard. The results showed that the linear relationship of pymetrozine is good in the concentration range of 50-10 000 μg/L with the relative coefficient more than 0.98, RSD of intra assay precision is less than 15%. After oral administration, pymetrozine was distributed in all organs of rats. At 10 min, the drug concentration in the lung was the highest, followed by spleen, heart, muscle and brain. Compare the changes of drug concentration in different organ tissues over time, it can be found that the peak time of drug concentration in brain and muscle appeared at 10 min, while in other tissues appeared at 2 h. The peaks were sorted in descending order, and the results were: liver>spleen>heart>lung>kidney>muscle>brain>testis>fat.After the drug concentration peaked, the drug concentration in each organ tissue gradually decreased with time. By 144 h, no pymeidone could be detected in all organs except for a small amount of pymetrozine. This result is consistent with the plasma kinetics results, which proves that the pesticide does not accumulate in rats for a long time and has high safety. The above results indicate that pymetrozine can be widely distributed in various organs of rats, and its dynamic distribution in tissues is basically consistent with the trend in plasma, and the elimination is faster, no accumulation tendency. At the same time, pymetrozine can quickly reach the brain tissue through the blood-brain barrier, or enter the testicular tissue through the blood testis barrier, but by 144 h, it is eliminated to below the minimum detection limit, and it has no teratogenic effects. These results provide a basis for the chronic toxicity of pymetrozine and the dose selection for carcinogenicity studies, and provide data support for its safety evaluation and methodological references for subsequent researchers. In this study only the distribution of pyridoxine prototype in rats was examined, and its metabolites was not able to be detected. It is necessary to develop more precise methods to conduct in deep studies to clarify distribution and excretion of metabolites in animals.