A method using liquid–liquid extraction (LLE) coupled with dispersive SPE (dSPE) clean-up was developed for the quantitative determination of 34 multiclass multi-residue (MCMR) pesticides in non-alcoholic carbonated beverages (cola, orange, lemon-lime and citra) using GC with tandem MS.
“Of the four varieties of non-alcoholic carbonated beverages, three (cola, orange, and citra) were found to contain pesticide residues,” said the researchers.
Procedure steps
The procedure involved LLE by dichloromethane and dSPE clean-up in the presence of magnesium sulfate, primary secondary amine and C18.
GC-MS/MS analysis was done using a Thermo Scientific TRACE Ultra gas chromatograph coupled to a triple quadrupole Quantum XLS mass analyser.
Pesticides were 14 organochlorines, eight organophosphates, 10 synthetic pyrethroids and two herbicides.
The LOD and LOQ values for analyzed pesticides were found in ranges of 0.001–0.027 μg/L and 0.004–0.088 μg/L, respectively. The LOQ levels were found to be well below the recommended limit by the European Union (0.1 μg/L in water).
The mean recoveries of pesticides in different non-alcoholic carbonated beverages (cola, orange, lemon-lime, and citra) were in the range of 79–111%.
The relative standard deviations (RSDs) of recovery estimation at different spiking levels (0.1, 0.5, and 1 μg/L) in different non-alcoholic carbonated beverages (cola, orange, lemon-lime, and citra) were in the range of 1.20–10.79%.
Common source of contamination
Many ingredients in non-alcoholic carbonated beverages (flavouring agents, sweeteners, etc.) are from agricultural products that can be a potential source of contamination from pesticide residues.
Presence of pesticide residues in non-alcoholic carbonated beverages could be a significant route of exposure to such residues in consumers because these drinks are highly consumed worldwide.
Existing methods are mainly based on LLE of the samples by petroleum ether and clean-up with gel permeation chromatography and Florisil.
These are labour intensive, time-consuming and require lengthy sample clean-up processes that can result in increased matrix interferences and decreased accuracy.
“The LLE technique is coupled with dSPE clean-up. This coupling gives an efficient extraction with high enrichment of the multi-residue pesticides from non-alcoholic beverages and with reduced interferences from the matrix. DCM was selected as an extraction solvent in LLE because of its high extraction efficiency,” said the researchers.
“Clean-up by dSPE was effective in removing the coextractives, which in turn, minimized matrix interferences with simultaneous improvement in the selectivity and accuracy of the method.”
Source: Journal of AOAC International, Volume 100, Number 3, May-June 2017, pp. 624-630(7)
“A Rapid Method for the Quantitative Determination of 34 Pesticides in Nonalcoholic Carbonated Beverages Using Liquid–Liquid Extraction Coupled to Dispersive Solid-Phase Cleanup Followed by Gas Chromatography with Tandem Mass Spectrometry”
Authors: Rai, Satyajeet; Gullapalli, Madhuri Devi; Srivastava, Anshuman; Shaik, Hussain; Siddiqui, Mohammed Haris; Mudiam, Mohana Krishna Reddy