Method development of multi pesticide residue analysis in country beans collected from Dhaka, Bangladesh, and their dietary risk assessment

The aim of the study was to develop a modified QuEChERS method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of five multi-class pesticides in country beans collected from Dhaka, Bangladesh. Pesticides were extracted using ACN, and to minimize the co-extraction matrix, optimized d-SPE cleanup was done using sorbents (GCB, PSA, and C18). In the calibration range, the method showed excellent linearity with a correlation coefficient of R2 ≥ 0.9990 both in solvent- and matrix-matched calibration. For the selected pesticides, average recoveries (at four spiking levels (n = 5) of 10, 20, 100, and 200 µg/kg) of 70-100 % were achieved with relative standard deviations (RSDs) ≤ 9.5 %. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.3333 to 1.3333 μg/kg and 1.0 to 4.0 μg/kg, respectively. The dietary risk assessment, in terms of hazard quotient (HQ), was calculated to assess consumers' health risks.

Development and validation of a modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole in brinjal collected from fields and markets places to assess human health risk

An effective and sensitive analytical method was developed to quantify the most common pesticide residues (difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole) used for brinjal cultivation in Bangladesh. The quantification of the analytes was done using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted using a modified QuEChERS method and followed by purification with dispersive solid phase extraction (d-SPE) sorbents (PSA, GCB, and C18). Matrix-matched calibration with a regression coefficient R² ≥ 0.9964 were used to minimize the brinjal matrix effect. The method was validated in quintuple (n = 5) at five different spiked levels (8-400 μg/kg) having recoveries in the range of 70.3-113.2% with relative standard deviations RSDs ≤6.8%, limits of detection (LOD) and limits of quantification (LOQ) was in the range of 0.15-0.66 μg/kg and 0.4-2.0 μg/kg, respectively, for the four analytes. A total 100 samples (50 samples directly from fields of Jessore district, Bangladesh and 50 samples from local market of Dhaka, Bangladesh) were collected to analyse the pesticides residue. The result showed that pesticides residue was found in both the field and market collected samples, 54% and 38%, respectively. The overall mean residue levels of four pesticides in field samples were significantly higher than those of market samples. Moreover, 20% of the field samples and 10% of the market samples had dimethoate residues, which were the most abundant among the four analytes and it ranged from 0.017 to 0.252 mg/kg. In terms of health risk assessments, dimethoate showed the highest estimated daily intake (EDI) and hazard quotient (HQ) values that are 3.02 × 10^-5 mg/kg/day and 1.51%, respectively, in field samples. Till now, there have been no regulations or guidelines for the maximum admissible pesticide residue in Bangladesh. Therefore, the above findings will be an initial step for the regulatory authorities of Bangladesh to implement regulations and guidelines for pesticide usage.