Two Analytical Methods for the Measurement of 2,4-D in Oranges: an ELISA Screening Procedure and a GC-MS Confirmatory Procedure

Abstract

: Two analytical methods are presented for the determination of 2,4-D in oranges.The screening procedure uses a commercial ELISA kit, designed for the determination of 2,4-D in water. Good semi-quantitative screening data were obtained provided that the standard solutions used to construct the calibration curve were prepared in blank orange extract. The limited quantiÐcation range of the kit was due to the narrow linear range and di †erences in response to 2,4-D when present as the free acid and as various esters.A GC-MS conÐrmatory technique involved extraction of 2,4-D from oranges by homogenisation with methanol, Ðltration and esteriÐcation/transesteriÐcation with boron triÑuoride-methanol. Recoveries for three spiking levels (0É2, 1É0 and 2É0 mg kg~1) for 2,4-D and 2,4-D isopropyl ester were within the range 75È 120%.In a small survey of retail oranges, 10 samples were screened using the ELISA kit and four were found to have [0É2 mg 2,4-D kg~1. All four residues were conÐrmed by GC-MS. The ELISA procedure involves approximately half the sta † e †ort of the GC-MS procedure.

Effects of Low, Subchronic Exposure of 2,4‐Dichlorophenoxyacetic Acid (2,4‐d) and Commercial 2,4‐d Formulations on Early Life Stages of Fathead Minnows (Pimephales promelas)

“…Analyses of random water samples from exposure tanks were carried out independently by the Wisconsin State Laboratory of Hygiene (University of Wisconsin-Madison, Madison, WI, USA). The 2,4-D ELISA is validated in the literature (Hall et al 1993;Lawruk et al 1994), is widely used for the detection of 2,4-D (by the Wisconsin State Laboratory of Hygiene and the University of Florida Center for Aquatic and Invasive Plants, Gainseville, FL, USA), and is used to verify permitted applications of 2,4-D in the field (Williams et al 1997;Chuang et al 2005;Glomski and Netherland 2010;Vdovenko et al 2013;Nault et al 2014Nault et al , 2018. To use the ELISA, the Wisconsin State Laboratory of Hygiene confirmed that the quality control standard included in every kit was ±5 ppb, and each calibration curve had an R 2 value of >0.99.…”

Development of an Immunoassay (ELISA) for the Quantification of Thiram in Lettuce

“…Immunoassays such as the enzyme linked immunosorbent assay (ELISA) have proved to fulfill to these requirements. Over the past few years, many immunoassays have been developed for detecting numerous pesticides in foodstuffs ( − ).…”

Chemometric-assisted QuEChERS extraction method for post-harvest pesticide determination in fruits and vegetables

“…Some methods for the individual determination of 2,4-D, carbendazim, thiabendazole, iprodione, and prochloraz in food matrices have been previously reported using gas chromatography coupled to mass spectrometry (GC–MS) 8 9 , high-performance liquid chromatography (HPLC) 10 11 , and liquid chromatography coupled to tandem mass spectrometry (LC–MS) 3 12 . However, simultaneous determination of these five compounds in food samples is currently not available.…”