Analysis and dissipation of dislodgable residues of acephate, dimethoate and formetanate hydrochloride on citrus foliage

Abstract

Dislodgable residues of acephate and its hydrolysis product methamidophos, dimethoate and its oxygen analogue omethoate (dimethoxon), and formetanate hydrochloride on citrus foliage were determined by gas–liquid chromatography. The use of 5% OV‐101 coated on a Carbowax 20M surface‐modified support (Ultra‐Bond 20M) allowed the reproducible analysis of dimethoate and omethoate residues. Formetanate hydrochloride residues were analysed as the free base, without preparation of a derivative, on a column packed with 5% Apiezon N coated on 80–100 mesh Ultra‐Bond 20M. The dissipation of the residues of the three pesticides applied to citrus trees was studied. Acephate and formetanate hydrochloride dissipation curves followed first‐order kinetics; dimethoate residues were best characterised by two first‐order kinetic processes. The half‐life values were 8.2 days for acephate, undeterminably long for formetanate hydrochloride, and 2.2 days (the 1–10 days portion) and 7.0 days (the 10–49 days portion) for dimethoate.

Determination of Glyphosate and (Aminomethyl)phosphonic Acid in Soil, Plant and Animal Matrixes, and Water by Capillary Gas Chromatography with Mass-Selective Detection

“…Citral was added to the injection solvent at a rate of 2 µ of solvent. The presence of citral appeared to help maintain a deactivated inlet and column, and thus reduce adsorption of the analytes, and thereby improving peak shape and low-level detectability (Hadjidemetriou et al, 1985). However, due to buildup of nonvolatiles it was found necessary to regularly replace (every 40-200 injections) the inlet liner and remove the first 1-2 ft of column to maintain optimum chromatog- AMPA standard (1.0 ng/mL each prederivatized analyte), (B) extract of sandy loam soil fortified at 0.05 mg/kg (0.02 g of soil/mL of extract), and (C) extract of unfortified sandy loam soil (0.02 g soil/mL of extract).…”

Residues of pesticides acephate and methamidophos in capsicum grown in greenhouse and open field

“…The extraction and clean‐up of capsicum samples for residues of acephate and its metabolite methamidophos were carried out as per procedure reported by Hadjidemetriou et al . (). The sample extract obtained was filtered through anhydrous sodium sulphate.…”

Effects of Rimsulfuron Lateral Relocation on Creeping Bentgrass (Agrostis stolonifera)

“…In other studies, insecticides were dislodged from citrus trees (Citrus spp.) (Hadjidemetriou et al 1985) and cotton (Gossypium hirsutum L.) (Estesen et al 1982). In both cases, Ͼ50% of applied insecticide persisted on leaf surfaces for 2 d, and detectable concentrations were recovered after 8 d.…”