Abstract
Mineral water is known for its high purity. Because mineral water is produced by the infiltration of water through the soil, there is the possibility of contamination with pesticides. The aim of this study was to develop a simple, rapid and efficient method for the extraction and preconcentration of different classes of pesticides in mineral water samples by dispersive liquid-liquid microextraction (DLLME) coupled with liquid chromatography tandem mass spectrometry. To optimize the DLLME conditions for the different classes of pesticides and access the effect of variables on the extraction, a central composite design (CCD) with a five-level fractional factorial design was used for the construction of a second order response surface model (RSM). The limits of quantification were between 0.005 and 0.5 μg L-1. Correlation coefficients (r) were higher than 0.999. Recoveries ranged from 102 to 120%, with relative standard deviations between 1 and 10%. Low matrix effect for all compounds was observed. The result showed that using a mixture of acetone and acetonitrile as disperser solvent and a mixture of chloroform and monochlorobenzene as extractor solvent, it is possible to employ the traditional DLLME with chlorinated solvents to extract the multiclass pesticides from the water samples.
Highlights
The quality of surface water is affected by several types of contamination
Selection of extraction and disperser solvents The selection of the extraction solvent is an essential parameter in dispersive liquid-liquid microextraction (DLLME), and certain criteria must be met for a suitable choice: extraction capability of the investigated compounds, good chromatographic behavior, low solubility in water, high extraction efficiency, and the solvent should form a cloudy solution in the presence of a disperser solvent when injected into an aqueous solution.[7]
To verify the method performance when applied for different samples, including sparkling and still ones, samples were spiked in a concentration level equivalent to 5-fold limit of quantification (LOQ) of each compound and submitted to the optimized extraction process
Summary
The quality of surface water is affected by several types of contamination. The development of agriculture has significantly affected natural resources, including surface water, mainly through the application of pesticides.[1] Due to the environmental conditions and the their physicochemical properties, pesticides can leach through the soil reaching groundwater such as mineral water.[2]. Due to the pollution of surface water, currently, mineral water is even more relevant as a source of water for human consumption. Mineral water has some medicinal properties that make it advantageous in comparison to surface water, i.e., it is naturally enriched with salts that provide benefits to human health.[3]. Once mineral water samples are formed through the water infiltration in the soil, pollution by pesticides can occur, which deserves investigation.
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