Validation of the method for the determination of dithiocarbamates in fruits

Abstract

Residues of active substances, which were frequently found in fruits and vegetables of market producers belonged to the dithiocarbamate group pesticide. According to their use dithiocarbamates belong to fungicides in terms dithiocarbamic acid. They are a group of compounds that exist as strong complexes with various metal ions, often in a polymeric form. This makes them difficult to analyse directly because of their limited solubility in most organic solvents. It is important to have a reliable method which enables the quick and simple detection of this group for official monitoring. This work reports a simple, rapid and sensitive method for the assessment residues dithiocarbamates in fruits. Dithiocarbamates were determined indirectly by measuring the amount of carbon disulfide (CS>) that is liberated by the chemical reaction. The fruit samples in undisturbed condition were heated with a solution of stannous (II) chloride and hydrochloric acid yielding carbon disulphide. Incurred carbon disulfide (CS) are determined "head-space" technique of gas-chromatography with mass detector. Linearity was verified by using the solutions of carbon disulphide in acetone. A linear dynamic range was obtained over a range of concentrations from 0.02 to 0.12 mg/kg for carbon disulfide with correlation coefficient r > 0.995. The accuracy of the method was acceptable since the average recoveries measured at four fortification levels were in the range of 83-103% (n = 4). The precision of the developed procedure expressed as the relative standard deviations (RSDs) were lower than 3.7% in all cases. Quantification was based on external standard calibration curves made with spiked blankmatrices.