Gas chromatographic method for the analysis of metaldehyde in crop tissue

Abstract

A simple and sensitive gas chromatographic ionization gas chromatography. Recoveries of 94 method is described for the analysis of residues of to 102% were obtained for artichoke and strawthe molluscicide metaldehyde ip crop tissue. berry samples fortified a t 0.1, 1.0, and 10 ppm. After extraction with benzene and cleanup on Acetaldehyde as well as other aldehydes and keFlorisil, metaldehyde was converted to acetaldetones may be determined separately by the same hyde, which was determined as its 2,4-dinitroderivatization procedure through analysis of the phenylhydrazone derivative using alkali-flame sodium bisulfite extract of the benzene solution.Since its accidental discovery as a snail and slug attractant and poison (Hadden, 1936), metaldehyde (2,4,6,8-tetramet hyl-1,3,5,7 -tetroxocane) has been widely used in spray and bait formulations for control of these pests in several vegetable and fruit crops. The molluscicide currently has a tolerance of 0 on food crops. Its use is thus restricted to applications which result in no residue in edible fruit or foliage. An efficient and sensitive method is required to support continued use and allow study of the degradation and metabolism of metaldehyde in the environment.Reported methods for quantitative analysis of metaldehyde residues are based on acid hydrolysis to form acetaldehyde which is steam distilled and determined photometrically after reaction with p-phenylphenol. Giang and Smith (1956) reported determination of fortifications as low as 1.8 ppm using this colorimetric method. The procedure was modified by Bowman et al. (1961) to allow extension to analysis of acetals, vinyl ethers, and other compounds which liberate acetaldehyde upon vigorous acid hydrolysis. Kimura and Miller (1964) included a Florisil column cleanup step to minimize interference. Even with this modification, background from control samples ranged from 0.1 to 0.7 ppm of metaldehyde equivalent in corn, bean foliage, and strawberry fruits. These high control levels, probably generated to a considerable extent during the hydrolysis step, make applications to residues less than 1 ppm subject to considerable variability.The following method provides quantitative determination of metaldehyde a t the 0.1-ppm level with little interference. It is based on conversion of metaldehyde to acetaldehyde a t room temperature, formation of the 2,4-dinitrophenylhydrazone (DNPH) and subsequent determination of the derivative by gas chromatography using the nitrogen-selective alkali-flame ionization detector. Acetaldehyde, occurring naturally in the crops and from possible decomposition of metaldehyde, is first removed from the benzene extract by washing with sodium bisulfite; it may then be determined by the same derivatization procedure if desired. EXPERIMENTAL SECTIONReagent grade tetrahydrofuran, sodium metabisulfite, 2,4-dinitrophenylhydrazine (Matheson, Coleman and Bell), acetaldehyde, Nanograde benzene (Mallinckrodt), and Florisil (PR grade, 60/100 mesh, Floridin Co., moisture content 6.7% by weig...

Developmental toxicity of metaldehyde in the embryos of Lymnaea stagnalis (Gastropoda: Pulmonata) co-exposed to the synergist piperonyl butoxide

“…However, metaldehyde is not effectively removed through adsorption onto activated carbon and hence there is considerable work to find effective removal methods (Li et al, 2010;Autin et al, 2012). Unsurprisingly, metaldehyde residues have also been detected in crops and in soil sampled from various regions (Selim & Seiber 1973;Zhang & Dai 2006;Zhang et al, 2011).…”

Review of the molluscicide metaldehyde in the environment

“…4,60 Gas chromatography methods Early work used GC to detect metaldehyde in a range of matrices after its conversion to acetaldehyde 61 or by using derivatisation techniques. 62,63 More recently, GC/MS has proved popular for the analysis of metaldehyde, being a robust and relatively simple methodology. 64,65 Most workers use similar GC conditions with a non-polar column such as DB5-MS. 66 Typically, metaldehyde has a short retention time (typically ≲8 min) on this stationary phase.…”

Determination of metaldehyde in different commercial pesticide formulations using green analytical procedure and gas chromatography flame ionization detection

“…These include simple systems like gas chromatography with flame ionization detector (GC-FID) employed for determination of metaldehyde in animal materials or nitrogen-phosphorus detector (NPD) used upon prior metaldehyde derivatization in citrus fruit and tobacco plants [7][8][9]. Metaldehyde residues were also determined using more complex systems like gas chromatography coupled with mass spectrometry (GC-MS) (determination of metaldehyde in water and riverbed deposits in the case of metaldehyde poisonings and residue analyses in foods) [10][11][12][13], liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) (metaldehyde determination in vegetables, soil, and water) [14][15][16][17][18][19], and headspace gas-chromatography coupled with mass spectrometry (HS-GC-MS) (metaldehyde determination in human plasma) [20], as well as gas chromatography with a less popular rubidium sulfate alkali-flame ionization detector (AFD) [21].…”