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

Summary

Presented here is a protocol for the determination of the absorption, translocation, and distribution of imidacloprid in wheat under hydroponic conditions using liquid chromatography-tandem mass spectrometry (LC-MS-MS). The results showed that imidacloprid can be absorbed by wheat, and imidacloprid was detected in both the wheat roots and leaves.

Abstract

Neonicotinoids, a class of insecticides, are widely used because of their novel modes of action, high insecticidal activity, and strong root uptake. Imidacloprid, the most widely used insecticide worldwide, is a representative first-generation neonicotinoid and is used in pest control for crops, vegetables, and fruit trees. With such a broad application of imidacloprid, its residue in crops has attracted increasing scrutiny. In the present study, 15 wheat seedlings were placed in a culture medium containing 0.5 mg/L or 5 mg/L imidacloprid for hydroculture. The content of imidacloprid in the wheat roots and leaves was determined after 1 day, 2 days, and 3 days of hydroculture to explore the migration and distribution of imidacloprid in wheat. The results showed that imidacloprid was detected both in the roots and leaves of the wheat plant, and the content of imidacloprid in the roots was higher than that in the leaves. Furthermore, the imidacloprid concentration in the wheat increased with increasing exposure time. After 3 days of exposure, the roots and leaves of the wheat in the 0.5 mg/L treatment group contained 4.55 mg/kg ± 1.45 mg/kg and 1.30 mg/kg ± 0.08 mg/kg imidacloprid, respectively, while the roots and leaves of the 5 mg/L treatment group contained 42.5 mg/kg ± 0.62 mg/kg and 8.71 mg/kg ± 0.14 mg/kg imidacloprid, respectively. The results from the present study allow for a better understanding of pesticide residues in crops and provide a data reference for the environmental risk assessment of pesticides.

Introduction

In present day agronomy, the use of pesticides is essential to increase crop yield. Neonicotinoid insecticides alter the membrane potential balance by controlling nicotinic acetylcholine receptors in the insect nervous system, thereby inhibiting the normal conduction of the insect central nervous system, leading to the paralysis and death of the insects¹. Compared with traditional insecticides, neonicotinoids have advantages such as novel modes of action, high insecticidal activity, and strong root absorption, making them highly successful in the pesticide market^2,3. The sales volume of....

Protocol

1. Germination of wheat seeds

1. Select 1,000 wheat seeds (Jimai 20) with complete granules, intact embryos, and uniform size (length: 6 mm ± 0.5 mm).
2. Transfer 333.3 mL of 30% H₂O₂ solution to a 1 L volumetric flask and dilute with deionized water to prepare 1 L of 10% H₂O₂ solution. Immerse the wheat seeds in 10% H₂O₂ solution for 15 min to disinfect the seed surface (Figure 1).
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Discussion

In recent years, methods for the pretreatment and detection of residues of the pesticide imidacloprid have been frequently reported. Badawy et al.²³ used high-performance liquid chromatography to determine the content of imidacloprid in tomato fruit grown under greenhouse conditions and reported good linearity for imidacloprid in the range 0.0125-0.15 µg/mL. Zhai et al.²⁴ used LC-MS-MS to study the residue of imidacloprid in Chinese chives. In the present study, the Qu.......

Materials

Name	Company	Catalog Number	Comments
Acetonitrile	Sigma-Aldrich (Shanghai) Trading Co. Ltd.	01-06-1995	Suitable for HPLC, gradient grade, >99.9%
Analytical balance	Sartorius Lab Instruments Co.Ltd.	GL124-1SCN
Artificial climate incubator	Shanghai Badian Instrument Equipment Co. Ltd.	HK320
Centrifuge	Eppendorf China Co. Ltd.	Centrifuge5804
Disposable syringe	Sigma-Aldrich (Shanghai) Trading Co. Ltd.	Z116866	Capacity 5 mL, graduated 0.2 mL, non-sterile
Formic acid	Sigma-Aldrich (Shanghai) Trading Co. Ltd.	Y0001970	European pharmacopoeia reference standard
Graphitized carbon black (GCB)	Sigma-Aldrich (Shanghai) Trading Co. Ltd.	V900058	45 μm
H2O2	Sigma-Aldrich (Shanghai) Trading Co.Ltd.	31642	30% (w/w)
Hoagland’s Basal Salt Mixture	Shanghai Yu Bo Biotech Co. Ltd.	NS1011	Anhydrous, reagent grade
Hydroponic equipment	Jiangsu Rongcheng Agricultural Science and Technology Development Co.Ltd.	SDZ04BD
Hypersil BDS C18 column	Thermo Fisher Scientific (China) Co. Ltd.	28103-102130
Imidacloprid	Sigma-Aldrich (Shanghai) Trading Co. Ltd.	Y0002028	European pharmacopoeia reference standard
MgSO4	Sigma-Aldrich (Shanghai) Trading Co. Ltd.	208094	Anhydrous, reagent grade, >97%
NaCl	Sigma-Aldrich (Shanghai) Trading Co.Ltd.	S9888	Reagent grade, 99%
pH meter	Shanghai Thunder Magnetic Instrument Factory	PHSJ-3F
Phytotron box	Harbin Donglian Electronic Technology Co. Ltd.	HPG-280B
Pipettes	Eppendorf China Co. Ltd.	Research plus
Syringe filter	Sigma-Aldrich (Shanghai) Trading Co.Ltd.	SLGV033N	Nylon, 0.22 µm pore size, 33 mm, non-sterile
Ultra performance liquid chromatography tandem triple quadrupole mass spectrometry	Thermo Fisher Scientific (China) Co. Ltd.	UltiMate 3000
		TSQ Quantum Access MAX
Vortex mixer	Shanghai Yetuo Technology Co. Ltd.	Vortex-2
Wheat seed	LuKe seed industry		Jimai 20