IS 18601 : 2024 Determination of Dithiocarbamate Pesticide Residues in Fruits and Vegetables - Method of Test
1 SCOPE
1.1 This standard prescribes gas liquid chromatographic (GLC) method for the determination of dithiocarbamate (carbamodithioate) residues as carbon disulphide (CS2) in fruits and vegetables. 1.2 The limit of quantification (LOQ) of the method is 0.05 mg CS2/kg. However, different LOQ can be achieved based on the sensitivity of the instrument.
2 PRINCIPLE
2.1 The principle involves hydrolysis of dithiocarbamate residues in fruits and vegetable samples with hydrochloric acid and stannous chloride solution at elevated temperature. The evolved CS2 is partitioned into isooctane and determined by using gas liquid chromatography with an electron capture detector (ECD) or mass spectrometry (MS) [GLC-ECD/GLC-MS]. The concentration of CS2 in samples is calculated via external calibration, with the residue being expressed as CS2.
2.2 When applied for the analysis of dithiocarbamate residues in fruits and vegetables (brassica crops, allium crops, papaya, etc) containing high amount of sulphur compounds, higher sample blank values must be taken into account. Since all the dithiocarbamate compounds decompose to CS2 by acid degradation, this analytical method is not selective. The result is the measured total residues of all the dithiocarbamate related compounds and hence does not support for quantification of residues of individual dithiocarbamate compound. The limit of quantification (LOQ) of the method is 0.05 mg CS2/kg. (however, different LOQ can be achieved based on the sensitivity of the instrument).
NOTE - When applied for the analysis of dithiocarbamate residues in fruits and vegetables (brassica crops, allium crops, papaya, etc) containing high amount of sulphur compounds, higher sample blank values must be taken into account.