Determination of the Absorption, Translocation, and Distribution of Imidacloprid in Wheat

This method helps to answer how Imidacloprid is absorbed, transported, and distributed in wheat. The main advantage of this technique is the high sensitivity of imidacloprid detection, which can be widely used to determine imidacloprid in soil, water, plant, and other samples. To germinate the wheat seeds, select 1000 suitable seeds having complete granules, intact embryos, and uniform size.

Immerse the seeds in 10%hydrogen peroxide solution for 15 minutes to disinfect their surfaces. Then rinse the seeds five times by running sterile water for 10 seconds each time. Now, spread the wheat seeds evenly with the embryos pointing up in a glass Petri dish containing moist, sterile filter paper.

Place the Petri dish in an artificial climate incubator maintained at 30 degrees Celsius and 80%relative humidity. Culture the wheat seeds in the dark for three days until they germinate and develop roots. After the wheat seeds have germinated, place 15 wheat seedlings in a hydroponic apparatus containing 100 milliliters of half Hoaglands nutrient solution.

Then, place the entire hydroponic setup in an artificial climate incubator at 25 degrees Celsius and 80%relative humidity for seven days. To set up the pesticide exposure experiments with two different imidacloprid concentrations, prepare hydroponic devices containing half Hoaglands nutrient solution with either 0.5 milligrams per liter or five milligrams per liter of imidacloprid. Set up 15 hydroponic devices for each imidacloprid concentration group to ensure adequate samples during sampling.

Now, transplant 15 wheat plants post their seven-day hydroponic period into each prepared hydroponic device. Place the entire hydroponic setup in an artificial climate incubator for three days at 25 degrees Celsius and 80%relative humidity. Throughout the imidacloprid exposure period, collect roots and leaves from the plants daily.

For each imidacloprid concentration, integrate the wheat samples from every fifth of the 15 hydroponic devices as a parallel group. To extract imidacloprid from wheat roots, shred the wheat roots using scissors into approximately one centimeter pieces. Weigh 10 grams of the shredded wheat roots and place them in a 50 milliliter centrifuge tube.

Then, add 10 milliliters of acetyl nitrile to the centrifuge tube and vortex the tube for one minute before adding four grams of anhydrous magnesium sulfate and 1.5 grams of sodium chloride to the tube. Immediately vortex the tube for 30 seconds. Next, centrifuge the tube at 6, 000 G for five minutes.

Aspirate the supernatant with a disposable syringe and pass it through a 0.22 micron syringe filter to obtain the sample. To extract imidacloprid from wheat leaves, shred the fresh leaves using scissors into pieces of approximately one centimeter. Weigh 10 grams of the shredded wheat leaves and place them in a 50 milliliter centrifuge tube.

Add 10 milliliters of acetonitrile to 10 grams of the shredded wheat leaves in a 50 milliliter centrifuge tube and vortex for one minute. Then treat the mixture with anhydrous magnesium sulfate and sodium chloride, and centrifuge as demonstrated previously. To remove pigmentation and moisture from the sample, take two milliliters of the supernatant obtained after the centrifugation and add it to a five milliliter centrifuge tube containing graphitized carbon black and anhydrous magnesium sulfate.

After 30 seconds of vortex mixing, centrifuge the tube at 6, 000 G for five minutes, followed by aspirating the supernatant with a disposable syringe and passing it through a 0.22 micron syringe filter to obtain the sample. Use liquid chromatography tandem mass spectrometry to quantify the amount of imidacloprid from the wheat samples as described in the manuscript. The recovery yields of imidacloprid from wheat samples showed that the average imidacloprid recoveries from wheat roots and leaves exposed to 0.5 milligrams per liter of imidacloprid or lesser compared to the average recoveries from samples exposed to five milligrams per liter of imidacloprid.

Imidacloprid was detected in both roots and leaves of wheat plants even after one day of exposure, indicating its rapid absorbance and conductance into the plants. The imidacloprid content was higher on day three of exposure than on day one, and the imidacloprid concentration was consistently higher in the roots than in the leaves. No apparent inhibition of plant growth was observed, even after three days of imidacloprid exposure in plants exposed to imidacloprid as compared to the controls.

The root concentration factor, or RCF, in the treated samples was greater than one, indicating wheat has an enrichment effect on imidacloprid. However, the translocation factor, or TF, for leaves was less than one, suggesting that the pesticide was not easily transferred from the wheat roots to the leaves. The most important steps are the extraction and purification of imidacloprid.

Ensure that imidacloprid is extracted without loss during these steps.