Determination of Dithiocarbamate Fungicide Residues in Food by a Spectrophotometric Method Using a Vertical Disulfide Reaction System

• Published in: Journal of agricultural and food chemistry Vol. 49; no. 10; pp. 4521 - 4525
• Main Authors: Caldas, Eloisa D, Conceição, Maria Hosana, Miranda, Maria Clara C, de Souza, Luiz César K. R, Lima, Joaquim F
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-10-2001
• Subjects: Biological and medical sciences; Disulfides - chemistry; Ethylenebis(dithiocarbamates) - analysis; Fabaceae - chemistry; Food Analysis - methods; Food industries; Food toxicology; Fruit - chemistry; Fundamental and applied biological sciences. Psychology; Fungicides, Industrial - analysis; Oryza - chemistry; Pesticide Residues - analysis; Spectrophotometry - methods; Vegetables - chemistry; Complexation; Purification; Organic dithiocarbamate; Process improvement; Pesticides; Foodstuff; Thiram; Fungicide; Tailings; Analysis method; Spectrophotometry; Carbamate; Quantitative analysis; Chemical contamination
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf010124a

Dithiocarbamates are a class of fungicides extensively used in many crops worldwide. The current residue definition of dithiocarbamates in food for compliance with maximum residue limits, at national and international levels, is total residues arising from the use of any or each dithiocarbamate fungicide, determined as CS2. The analytical method most frequently used to analyze dithiocarbamate residues in food for monitoring purposes was proposed more than 30 years ago. In this method, total dithiocarbamates are decomposed to CS2, which is purified and reacted with a cupric reagent. The yellow complex formed is quantified by spectrophotometry. In this paper, a new reaction system for the purification and complexation of CS2 is proposed. The new system is less fragile than the traditional design, is easier to assemble, and allows for a higher sample throughput, in addition to being of low cost. Recovery of added mancozeb, thiram, or ziram (0.15−8.0 mg/kg) in rice, beans, apple, banana, orange, papaya, tomato, cucumber, and potato ranged from 82 to 120%, with relative standard deviations from 0 to 10% (n = 3 or 5). Analysis of apple, tomato, and papaya samples with field-incurred dithiocarbamate residues showed comparable results using both the traditional and the new reaction systems. Keywords: Dithiocarbamate fungicides; CS2 reaction system; spectrophotometry; food analysis