Determination of 4"-deoxy-4"-(epimethylamino)avermectin B1 benzoate (MK 0244) and its delta 8,9-isomer in celery and lettuce by HPLC with fluorescence detection

Abstract

An analytical method has been developed for the extraction, derivatization, and fluorescence HPLC determination of MK-0244 [4"-deoxy-4"-(epimethylamino)avermectin B1 benzoate salt] and its delta 8,g-isomer from lettuce and celery at trace (parts per billion) levels. MK-0244 and its delta 8,g-isomer are extracted with methanol, and the extract is cleaned up on a reverse-phase CS cartridge followed by a liquid-liquid extraction with ethyl acetate before passing through a propyl sulfonyl cation-exchange cartridge. MK-0244 and its delta 8,g-isomer are then derivatized with trifluoroacetic anhydride/ 1-methylimidazole/acetonitrile reagent system to form a fluorescent derivative which is separated on a reverse-phase HPLC system and detected with a fluorescence detector. The average recoveries were 95 f 10% for celery and 96 f 8% for lettuce. For both lettuce and celery matrix, concentrations as low as 2 ppb (SIN = 10) can be detected in a 10-g sample. This method was used to determine the MK-0244 levels in samples from a lettuce field trial.

Short communication. Toxicity of emamectin benzoate to adults of Nesidiocoris tenuis Reuter, Macrolophus pygmaeus (Rambur) (Heteroptera, Miridae) and Diglyphus isaea Walker (Hymenoptera, Eulophidae) on tomato plants. Semi-field studies

“…The fast degradation on the plant surface of the residues of emamectin benzoate is crucial for their selectivity (Prabhu et al, 1991). In accordance to this fast degradation on the surface, our semi-field assays with D. isaea and tomato plants showed IOBC toxicity ratings for fresh and 7-day-old-residues of 2 and 1, respectively, and in those assays with the two predators, class 1.…”

“…The most important factor is probably the faster photodegradation of the insecticide on the leaf surface that could happen in the greenhouse during the first hours after application compared to the effect of artificial light on detached leaves kept in Petri dishes in the laboratory (Jansson et al, 1997). A quick degradation and a faster absorption and translocation of emamectin diminish the amount of insecticide deposited on the plant surface and lower the possibility of poisoning the natural enemies due to contact with the insecticide, while the fast penetration provides enough amount of the product into the leaf tissues to ensure an effective control of plant feeding pests (Prabhu et al, 1991). Another factor to be taken into account is the greater ability of insects to avoid contact with pesticide deposits through increased mobility and successful location of shelters on whole plants compared to detached leaves.…”

Simultaneous Determination of Emamectin, its Metabolites, Milbemectin, Ivermectin and Abamectin in Tomato, Japanese Radish and Tea by LC/MS

“…Avermectin is a natural product in a culture of Streptomyces avermitilis and has the trade name of avermectin B 1 . 5) In Japan, emamectin benzoate and milbemectin are registered for use as pesticides by the Ministry of Agriculture, Forestry and Fisheries in 1998 and 1991, respectively.…”

The effect of emamectin benzoate on two parasitoids, Aphidius colemani Viereck (Hymenoptera: Braconidae) and Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), used in pepper greenhouses

“…The low persistence may explain the selectivity of emamectin benzoate aged residues found in the trial with A. colemani. Undetectable residues of the insecticide have been reported after 24 hours (Prabhu et al, 1991) due to the rapid degradation of the residues of emamectin benzoate on the plant surface (Ishaaya et al, 2002). As discussed by Lopez et al (2010), several factors may impact the effect of aged residues of emamectin benzoate under greenhouse conditions compared to laboratory conditions, being the most important the rapid photodegradation of the insecticide (Jansson & Dybas, 1998).…”