ELISA TEST F
Rapid ELISA test kit for the quantitation of glyphosate in durum wheat samples
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Eurofins Abraxis’ Glyphosate ELISA test kit
by Fernando Rubio, Lori fields and Thomas Glaze, Eurofins Abraxis, USA continues, consumer concerns about glyphosate in the food chain lyphosate or N-(phosphonomethyl) grow. The EPA (40 CFR Part 180) has established tolerances for glycine (See Figure 1) is the various commodities, grain cereals: oatmeal, wheat and barley world’s most widely used broadat 30 ppm or 30,000 ng/gm but organic standards for some spectrum herbicide and crop commodities are as low as 10 ppb (10 ng/gm). desiccant, accounting for about Glyphosate analysis in environmental matrixes is often 25 percent of the global herbicide problematic because it is a small molecule with structural market. similarity to many naturally occurring plant materials such as An organophosporous compound amino acids and secondary plant compounds. Its high-water (phosphonate), it was first solubility, makes solvent extraction difficult, posing a serious discovered to be an herbicide by Monsanto and introduced into challenge to chemists needing to remove matrix effects prior the market in 1974 under the trade name ‘Roundup’. Glyphosate to instrumental analysis. In addition, plant and soil matrixes is sometimes applied on barley, wheat and other crops as a precontain co-contaminants that increase complexity of sample harvest drying agent to speed up harvesting operations. preparation and make instrumental analysis costlier and more While glyphosate formulations such as Roundup have been time-consuming. approved by regulatory bodies worldwide, concerns about their Enzyme-linked immunoassay (ELISA) is an analytical effects on humans and the environment persist. Contradictory findings on carcinogenic risks have thrust glyphosate into the center of dispute between EU and US politicians, regulators and Table 1: Evaluation of Glyphosate ELISA reproducibility researchers. Sample # Extract 1 Extract 2 Extract 3 Average Stdev %CV Mean ELISA Mean ELISA Mean ELISA ELISA In March 2015 the World Health concentration concentration concentration concentration Organization (WHO) International Agency for (ng/gm) (ng/gm) (ng/gm) (ng/gm) Research on Cancer classified glyphosate as 1 640 603 570 604 35.0 5.8 “probably carcinogenic in humans” (category 2 15 8 14 12 3.4 27.4 2A) based on epidemiological, animal and in 3 18 19 20 19 1.1 5.9 vitro studies. In November 2015, however, 4 22 22 19 21 1.3 6.4 the European Food Safety Authority (EFSA) 5 8 <7.5 <7.5 <7.5 0.7 9.2 published a report concluding that “glyphosate 6 26 29 29 28 1.8 6.5 was unlikely to be genotoxic or pose a carcinogenic threat to humans”. 7 202 182 234 206 26.3 12.7 Amidst this contradictory information, in 8 18 22 20 20 2.0 9.9 June 2016, the European Commission could 9 846 656 714 739 97.4 13.2 not agree on re-registration of glyphosate 10 787 646 731 721 71.0 9.8 for another 15 years. Instead, it granted a 11 48 46 47 47 1.1 2.3 temporary license extension pending further 12 14 17 19 17 2.7 16.2 scientific studies. As the scientific debate
64 | July 2019 - Milling and Grain