New research techniques assess the metabolic behavior of herbicide absorption in vegetables

Schematic diagram of in vivo capillary sampling and rapid analysis of Chinese cabbage. Courtesy of the research team

Recently, the scientific research team of Guangdong Provincial Key Laboratory of Chemical Measurement and Emergency Detection Technology has established a new technology for in vivo microcapillary sampling (MCS) combined with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS). The study was published in Food Chemistry.

Paraquat and dichocendo are bipyridine cationic quaternary ammonium salts, which are highly water-soluble and lowly volatile, and are non-selective contact killer herbicides, which have been widely used as herbicides worldwide because of their low price. Paraquat and diffus are highly toxic to humans and animals, causing harm to the ecological environment and threatening human health through the food chain.

It was found that there was a significant difference in the rapid absorption capacity of Chinese cabbage on paraquat and enemy grass, and it was relatively easier to absorb enemy grass fast, and there were also significant differences in absorption between different Chinese cabbage individuals. The researchers developed MCS in vivo sampling and MALDI-FTICR-MS rapid analysis techniques. The technology has the characteristics of low cost, small sample usage, fast, high throughput, and high sensitivity, and the whole analysis process is completed within 20 minutes.

Long-term exposure experiments have found that a group of Chinese cabbage roots are continuously exposed to the water environment of paraquat and rapid contamination of enemy grasses (initial concentrations of 100 μg/L), and the roots of this group of Chinese cabbage will continue to absorb these two pollutants, and when the concentration of sap in the stem of Chinese cabbage reaches about 500 μg/kg respectively, it will cause the plant to wilt and die.

When the elimination experiment was carried out, the roots of living cabbage that absorbed paraquat and enemy grass were soaked in a blank culture medium, and the concentration of the two herbicides in the sap of the cabbage stem was gradually reduced, and paraquat and enemy grass fast were detected in the blank culture solution, indicating that the herbicide would be excreted by the cabbage through the root system in the form of a prototype.

Based on the results of the elimination tracking experiment, the half-lives of paraquat and dichlorvos were calculated to be 1.32 d and 1.86 d, respectively. On the 18th day of the elimination experiment, paraquat and dichlor were still detected in living cabbage, indicating that both were difficult to achieve complete clearance and degradation through the normal metabolism of the cabbage itself.

This research technique can monitor the concentration of bipyridine quaternary ammonium herbicide in living plants in real time, evaluate its absorption and elimination behavior in plants, and provide a valuable basis for the risk of human exposure caused by herbicide use in agricultural production. (Source: China Science Daily, Zhu Hanbin, Chen Chao)

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