Dispersive liquid–liquid microextraction of pesticides and metabolites from soils using 1,3‐dipentylimidazolium hexafluorophosphate ionic liquid as an alternative extraction solvent

Abstract

In this work, the use of the ionic liquid (IL) 1,3-dipentylimidazolium hexafluorophosphate ([PPIm][PF₆]) as an alternative extractant for IL dispersive liquid-liquid microextraction (IL-DLLME) of a group of pesticides and metabolites (2-aminobenzimidazole, carbendazim/benomyl, thiabendazole, fuberidazole, carbaryl, 1-naphthol, and triazophos) from soils is described. After performing an initial ultrasound-assisted extraction (USE), the IL-DLLME procedure was applied for the extraction of these organic analytes from soil extracts. Separation and quantification was achieved by high-performance liquid chromatography (HPLC) with fluorescence detection (FD). Calibration, precision, and accuracy of the described USE-IL-DLLME-HPLC-FD method using [PPIm][PF₆] as an alternative extractant was evaluated with two soils of different physicochemical properties. Accuracy percentages were in the range 93-118% with RSD values below 20%. A comparison of the performance of [PPIm][PF₆] versus that of the so-common 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF₆]) was accomplished. Results indicate a comparable extraction efficiency with both ILs, being slightly higher with [HMIm][PF₆] for the metabolite 2-aminobenzimidazole, and slightly higher with [PPIm][PF₆] for triazophos. In all cases, LODs were in the low ng/g range (0.02-14.2 ng/g for [HMIm][PF₆] and 0.02-60.5 ng/g for [PPIm][PF₆]). As a result, the current work constitutes a starting point for the use of the IL [PPIm][PF₆] for further analytical approaches.

Determination of estrogens in environmental water samples using 1,3‐dipentylimidazolium hexafluorophosphate ionic liquid as extraction solvent in dispersive liquid–liquid microextraction

“…As indicated in the introduction, the IL [PPIm][PF 6 ] has only been used once as extraction solvent in DLLME in a work developed by our research group. In this single application, it was applied for the IL‐DLLME extraction of a group of six pesticides and metabolites from soil extracts . The good results obtained strongly encouraged the application of this IL for the extraction of other families of compounds.…”

“…The IL [PPIm][PF 6 ] was synthesized, purified, and characterized by NMR following a procedure previously carried out by our group that consisted on a slight modification of a procedure previously published by Dzyuba and Bartsch .…”

“…In this respect, 1‐hexyl‐3‐methylimidazolium hexafluorophosphate ([HMIm][PF 6 ]) has been the most employed by far , followed by others like 1‐octyl‐3‐methylimidazolium hexafluorophosphate ([OMIm][PF 6 ]) or 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIm][PF 6 ]) . However, concerning the use of symmetrical 1,3‐dialkylimidazolium hexafluorophosphate ILs, only dibutyl ([BBIm][PF 6 ]) and dipentyl ([PPIm][PF 6 ]) have been employed in one occasion each for DLLME. In both works, the IL was synthesized, since they cannot be purchased in the market.…”

Alternative solvent-based methyl benzoate vortex-assisted dispersive liquid-liquid microextraction for the high-performance liquid chromatographic determination of benzimidazole fungicides in environmental water samples

“…Therefore, the development of sample preparation methods based on green analytical chemistry is of high impact to investigate and extend the application of newly designed DLLME for the analysis of benzimidazole fungicides. The elimination or replacement of toxic reagents is also further expected such as the use of lighter density (e.g., hexane) , and ionic liquid as a greener solvent . However, the use of a solvent of lighter density normally requires a special device for phase separation and it is sometimes difficult to collect the extract phase.…”

“…However, the use of a solvent of lighter density normally requires a special device for phase separation and it is sometimes difficult to collect the extract phase. Meanwhile, ionic liquids are relatively expensive and required a synthesis step in some cases . The alternative extraction solvents should have the following requirements: (1) higher density than of water, (2) low water solubility, (3) good extraction performance of the interesting analytes, (4) low UV absorption or not interfere with target analyte peaks, and (5) low cost.…”