Imidacloprid

Imidacloprid Synthetic chloro-n icoti nyl insecticide Insect CNS nAChR... 

Imidacloprid is a widely used neonicotinoid insecticide that kills pests by targeting their central nAChRs. Levamisol is used to kill nematodes by acting on nAChRs in the worm s muscles. 

At a more subtle level, behavioral disturbances may make it more difficult for animals to find food. Pyrethroids, carbamates, OPs, and neonicotinoids can disturb the foraging activity of bees (Thompson 2003). Interestingly, effects have been shown upon the wagtail dance of bees, and this disrupts communication between individuals as to the location of nectar-bearing plants. Also, the neonicotinoid imidacloprid has been shown to adversely affect conditioned responses such as proboscis extension of honeybees (Guez et al. 2001). Nicotinoids can disturb the functioning of cholinergic synapses, which are involved in the operation of the proboscis reflex as... 

Beta nicotinic acid to 6-hydroxy nicotinic acid 3-substituted pyridine to a building block for imidacloprid (an insecticide) R-Cyanohydrins from benzaldehydes and HCN ... 

Figure 1 SRM chromatograms of (a) fenamiphos and metabolites and (b) imidacloprid and metabolites. IS refers to the stable labeled isotopes. The values below the names refer to the mass transitions, i.e., M -b 1 -> product ion for the metabolite...

A.S. Felsot, R.G. Evans, and J.R. Ruppert, Field studies of imidacloprid distribution following application to soil through a drip irrigation system , in Terrestrial Field Dissipation Studies Design, Interpretation and Purpose, ed. E.L. Arthur, V.E. Clay, and A. Barefoot, ACS Symposium Series No. 842, American Chemical Society, Washington, DC (2003). 

Neonicotinoids are potent broad-spectrum insecticides that exhibit contact, stomach and systemic activity. Acetamiprid, imidacloprid, nitenpyram, thiamethoxam and thiacloprid are representatives of the neonicotinoid insecticides (Figure 1). The mechanism of action is similar to that of nicotine, acting on the central nervous system causing irreversible blocking of postsynaptic nicotinic acetylcholine receptors (nAChR). Neonicotinoid insecticides are often categorized as antagonists of the... 

In general, neonicotinoids (except for nitenpyram) are metabolized slowly in plants, and remain mainly as the parent compounds. The definition of crop residues is for the acetamiprid and imidacloprid parent molecule. The definition of crop... 

Alba et al. used ethyl acetate to extract imidacloprid residues from fruits and vegetables. A 15-g sample of vegetable or fruit is weighed into a blender tube and 60 mL of ethyl acetate and 15g of sodium sulfate are added. The mixture is homogenized for 30 s, using a Polytron, and filtered. The filtrate is evaporated and the residue obtained is dissolved in acetonitrile-water (1 1, v/v). Alba etal. considered the low recoveries of these polar pesticides as the major disadvantage of the acetone extraction method. In their previous work they evaluated the efficacy of ethyl acetate for the extraction of pesticide residues. 

For imidacloprid, the combined Altrates are concentrated with a rotary evaporator. The Anal residue is dissolved in 5 mL of n-hexane and applied to a silica gel cartridge, preconditioned with 5 mL of n-hexane. The n-hexane solution is transferred into the carAidge, which is rinsed with 5mL of n-hexane-ethyl acetate (1 1, v/v) and eluted with 8 mL of ethyl acetate. Further cleanup could be carried out using a Florisil carAidge, if needed. The imidacloprid residue in 4 mL of n-hexane-acetone (13 7, v/v) is eluted with 8 mL of n-hexane-acetone (2 3, v/v). The eluate is concentrated under vacuum on a rotary evaporator at 40 °C. The residue obtained is dissolved in a suitable volume of water-acetoniAile (4 1, v/v) and analyzed by HPLC (270 nm). ... 

Enzyme-linked immunosorbent assay (ELISA). Li and Li developed an ELISA procedure for imidacloprid to determine its residues in coffee cherry and bean extracts. A 25-g amount of sample extracted with 300 mL of methanol and 1% sulfuric acid (3 1, v/v) for 3 min. An aliquot of the sample extract (0.5 mL) is mixed with 1 mL of water and a gentle stream of nitrogen is used to evaporate methanol. The solution is then extracted with 1 mL of ethyl acetate, the extract is reconstituted in 1 mL of PBST (phosphate-buffered saline containing 0.05% Tween 20) and competitive ELISA is performed to quantify imidacloprid in the extract. Eor methanol extracts of coffee cherries and beans fortified with imidacloprid at 0.5 mgL recoveries of imidacloprid by the ELISA method were 108 and 94, respectively. 

Acetamiprid Imidacloprid Nitenpyram Thiaclopiid Thiamethoxam Imidacloprid... 

Analyte Acetamiprid Imidacloprid Nitenpyram metabolite Thiacloprid metabolite Thiamethoxam metabolite Imidacloprid... 

HPLC determination can be carried out for most of the neonicotinoids. The average recoveries of imidacloprid in the various crops by the HPLC/PDA method were 88-94% at a fortification level of 0.25 mg and 96-99% at a fortification level of 0.05 mg kg . The overall average recovery for 30 samples was 95% with an RSD of 4.7%.12... 

According to the official Japanese HPLC/UV method, the average recovery for grapes fortified with 0.2mgkg of acetamiprid was 96% and that for tomato fortified with 0.4mgkg of imidacloprid was 90% (personal data). The recovery of nitenpyram from fruits, vegetables and rice was 66-85% at 0.2-0.8 mg kg fortification levels. The LOD was 0.0025-0.01 mg kg ... 

LC/MS is used as a multi-residue analytical method. The recovery of imidacloprid from tomato was 90-105% for 0.05 and 0.5mgkg . The LOD for imidacloprid was < 10 pg kg in the full-scan mode and 1 pg kg in the selected-ion monitoring (SIM) mode. ... 

Extraction efficiency. The efficiency of extractions of imidacloprid from vegetables and crops decreases in the order acetonitrile > acetone > ethyl acetate. Acetonitrile is not a suitable extraction solvent because of the large number of co-eluting peaks on the chromatograms on HPLC at 210 or 270 nm. ... 

The polar character of neonicotinoids makes them, in general, potentially mobile in soil. Acetamiprid and nitenpyram have short soil persistence. Imidacloprid and thi-amethoxam, however, are sufficiently persistent in soil to be used for soil treatment. The definition of soil residues for the various neonicotinoid compounds except for imidacloprid are the parent compound and it metabolites. The metabolites of acetamiprid are lM-1-2, lM-1-4 and lC-0 (Figure 6). The metabolites of nitenpyram are 2-[N-(6-chloro-3-pyridyl-methyl)-A-ethyl]amino-2-methyliminoacetic acid (CPMA) and A-(6-chloro-3-pyridylmethyl)-Ai-ethyl-A -methylformamidine] (CPMF). 

Organic solvent extraction. Two analytical methods for acetamiprid have been developed One method is for the parent only and the other determines the total residue of the parent and its metabolites (lM-1-2, lM-1-4 and lC-0). Air-dried soil (20-g equivalent dry soil) is weighed into a centrifuge tube and imidacloprid residue is extracted with 100 mL of methanol-0.1M ammonium chloride (4 1, v/v) using a mechanical shaker for about 30 min. After shaking, the tube is centrifuged at 8000 rpm for 2 min. The supernatant is filtered and the analysis of the soil residue is carried out in the same manner as described above for the parent compound. 

The extraction method for imidacloprid residues has been presented by Westwood et al. A 20-g soil sample is extracted with 20 mL of acetonitrile-water (4 1, v/v) by... 

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... 

Eskilsson and Mathiasson reported a 97% recovery of imidacloprid from dust waste by the SFE method. 

The determination procedure is described in Section 2.2.4. The ELISA determination of water samples can be performed directly, such as for imidacloprid in tap water. ... 

The LODs for imidacloprid and metabolites, when determined by US Environmental Protection Agency (EPA) guidelines, are 0.021-0.024 ngL The LOQ is defined as 0.1 ng for each metabolite. Recoveries from control water samples fortified at the 0.1 and 1 ngL levels ranged between 84 and 107% for all metabolites. No relative standard deviation between the respective recoveries for any of the analytes was greater than 10%. 

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