New Chromogenic Reagent for Spectrophotometric Determination of Ethylene Bis-dithiocarbamate Pesticide Residues in Vegetables

Aim: The use of pesticides, mainly ethylene bis-dithiocarbamates (EBDCs) has been reported to be abusive in the North West Region (Cameroon) but due to limited analytical facilities there are very limited data on their concentrations in foods from the local milieu. This study aimed to develop a simple spectrophotometric method to monitor residue levels of EBDCs in vegetables in order to improve food safety measures.

Methodology: The analytical technique was based on the degradation of EBDCs in acidic medium in the presence of tin (II) chloride to liberate carbon disulfide which was absorbed by a new chromogenic reagent (silver nitrate/diethanolamine) and subsequently quantified spectrophotometrically at 410 nm.

Results: A good linearity (R2=0.999), practical detection limit (0.02 µg/mL), theoretical limit of quantification (20.04 µg/mL) of the method were established. The precision of the method was within the generally accepted interval for pesticides analysis. The analysis of the three selected vegetables revealed EBDC residue levels of 2.96, 6.34 and 7.92 mg/kg in parsley, huckleberry and tomato samples, respectively. These levels exceeded the maximum residue levels recommended by EFSA (2019) and FAO/WHO (2020).

Conclusion: The developed method was simple, rapid, and easy to use for the estimation and control of residue levels of EBDC in vegetables.