Abstract
Various greener microextraction procedures have been proposed with low limits of detection to control of pesticides present in the environment, including the low-density solvent dispersive liquid‑liquid microextraction (LDS/DLLME) technique. The addition of electrolytes is important in order to induce the salting-out effect. Thus, it is possible to use the Hofmeister series and the Voet lyotropic number to study the effect of different ions on pesticide extraction in LDS/DLLME technique. Different anions were tested and a strong correlation was observed between the lyotropic number of the anion and the recovered volume of extraction solvent. The lyotropic numbers of the anions were successfully compared with the chromatographic peak areas normalized by the recovered solvent volumes, and similar empirical cubic relationships were obtained for all the pyrethroids evaluated. In the extraction of the organophosphorous pesticides, chlorpyrifos presented similarity with the pyrethroids, while correlation was observed between methyl parathion and profenofos.
Highlights
Pesticides have been used in food production since the early 20th century.[1]
The volume of toluene recovered after the addition of 100 μL in the dispersive liquid-liquid microextraction (DLLME) procedure was influenced by the type of anion present in the aqueous solution
Ion-specific effects exert an important influence on the efficiency of pesticide extraction using DLLME
Summary
Pesticides have been used in food production since the early 20th century.[1] More recently, there has been increasing concern about their effects on humans and other organisms. Efforts are being made to control the concentrations of these substances in different environmental compartments (including water, soil, and biota), as well as to identify less toxic compounds.[2,3] Because of the need for better control of pesticides in the environment, there is a requirement for analytical methods that offer lower limits of detection and greater sensitivity. In addition to advances in terms of instrumentation, a variety of pre-extraction techniques have been proposed, such as solid phase microextraction (SPME),[4] single drop microextraction (SDME),[5,6] dispersive liquid-liquid microextraction (DLLME),[7] dispersive liquid‐liquid microextraction method based on solidification of floating organic drop (DLLME-SFO),[8,9] and low-density solvent dispersive liquid-liquid microextraction (LDS/DLLME).[9,10] These methods complies with the principles of green chemistry, because it minimizes the use of organic solvents as well as the amounts of waste generated[11,12] and they can even help to extend the useful life of older and less sensitive instruments
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