Flow Injection/Atomic Absorption Spectrometric Determination of Zineb in Commercial Formulations of Pesticide Based on Slurry Sampling

Abstract

Dithiocarbamates are synthetic molecules frequently employed as pesticides to treat a wide variety of fungal diseases in plants. Their use has increased throughout the world, being applied in large scale in several types of crops. Dithiocarbamate compounds are classified from medium to highly toxic substances, depending on their structure. 1 Zineb {[ethylenebis(dithiocarbamato)]zinc} is one of the most utilized pesticides to protect fruits and vegetables from foliar diseases, and is also employed in the protection of such products during their storage and transportation. 1 When released to the terrestrial environment, zineb adsorbs strongly to soil particles and usually does not move below to the upper layer of the soil.Due to this behavior, groundwater contamination by zineb is unlikely to be reported in the literature. The bioactive half-life of zineb in the field is estimated to be 16 days, and the most common problem associated to zineb application on soils is the formation of ethylene thiourea (ETU), which is a very toxic metabolite of the pesticide. 2 Most general dithiocarbamate determinations are based on their hot acid decomposition, followed by the detection of CS2 evolved after its collection in a suitable solution. [3][4][5] This approach was first proposed by Clarke et al. 3 and Lowen, 4 who employed different methodologies for CS2 quantification. Afterwards, other researchers applied the same approach, just detecting the CS2 formed by several other instrumental techniques, such as head space gas chromatography, 6 differential pulse polarography, 7 Fourier-transform infrared spectrometry 8 or UV-visible spectrophotometry. [9][10][11] During the last ten years, direct determinations of zineb (without hot acid decomposition) have also been carried out by spectrophotometry, 12,13 16 used a C60 fullerene column for zineb preconcentration (among other dithiocarbamate pesticides) in a flow system. After elution with a 0.2 mol l -1 HNO3 solution, the pesticide was injected in a flame AAS and the zinc was detected for quantification purposes. The aim of this work was to carry out a direct determination of zineb in commercial formulations by employing a novel strategy based on a slurry sampling technique integrated to a flow injection-flame AAS system, thus eliminating the necessity of laborious and time-consuming sample pretreatments, such as solvent extraction or hot acid decomposition of the pesticide. Moreover, the use of toxic organic solvents is avoided and the possibility of sample contamination and analyte losses is minimized. Also, the proposed procedure can be employed in routine analysis without involving the use of high-cost reagents or expensive instrumentation. Universidad de Valencia, Dr. Moliner 50, Burjassot, Valencia, 46100, Spain This paper reports on a new strategy for the slurry sampling determination of dithiocarbamate pesticide zineb {[ethylenebis(dithiocarbamato)]zinc} employing a FIA system with a flame atomic absorption spectrometry detector. In the flow system, an on-line alka...

Types, principle, and characteristics of tandem high-resolution mass spectrometry and its applications

“…99,100 Therefore, monitoring pesticide residues in food commodities is necessary for not only the protection of human health but also identifying the maximum residue limits (MRLs) for safe human consumption, which are set by the European Commission. Various analytical methods and techniques have been used to monitor pesticide residues in food, including spectrophotometry, 101 polarography, 102 atomic absorption spectrometry, 103 and mass spectrometry. 104 Currently, liquid chromatography coupled with QqQ-MS is frequently used in multiple residue analysis.…”

Development of a derivative spectrophotometric method for the determination of fungicide zinc ethylenebisdithiocarbamate using sodium molybdate

“…Many methods like spectrophotometry, 1,[3][4][5][6][7][8] flame atomic absorption spectrometry 9,10 FT-IR, 11 gas chromatography, 12,13 HPLC, [14][15][16] polarography, 17,18 biosensors, 19 and enzyme linked immuno sorbent assay 20 are available for Zineb determination and other dithiocarbamates. Most of the applied methods use different techniques like spectrophotometry and gas chromatography 3 based on analysis of CS 2 , H 2 S or amines which are evolved by the decomposition of EBDCs.…”

Flow injection-photoinduced-chemiluminescence determination of ziram and zineb

“…These authors were able to analyse 46 analytes out of 52 targets by using a mass spectroscopy detector, however ziram was one of the six for which no result was obtained and zineb was not tested. Other alternative analytical methods such as atomic absorption spectroscopy 6,[18][19][20] , capillary electrophoresis 21 and amperometry 22 have been also developed but they are less sensitive than the CL-FIA method herein reported. Moreover some of them require extraction with organic solvents, which is sometimes tedious, time-consuming and prone to errors due to incomplete extraction.…”