An Ionic Liquid-based Microextraction Method for Ultra-High Preconcentration of Paraquat Traces in Water Samples Prior to HPLC Determination

Development of a fluorescent probe for cefazolin detection based on solvent-based de-emulsification dispersive liquid-liquid microextraction of silver nanoparticles

A novel, simple, and rapid method has been developed for the fluorimetric determination of trace levels of cefazolin. The method is based on the synthesis of silver nanoparticles (AgNPs) as fluorescent probes using resorcinol as a reducing and capping agent and then their extraction into the 1-octanol by a highly efficient solvent-based de-emulsification dispersive liquid-liquid microextraction technique. The interaction of cefazolin with silver affected the fluorescence intensity of AgNPs in the organic phase that creates a micro-probe fluorimetric detection of this antibiotic at excitation/emission wavelengths of 410/527 nm. Under the established optimum conditions, the linear analytical range was from 0.80 to 12.00 ng mL^-1 of cefazolin with a detection limit of 0.55 ng mL^-1. The relative standard deviation for ten replicate measurements of 2 and 10 ng mL^-1 of cefazolin was 4.18 and 1.88%, respectively. The suggested method was successfully applied to the determination of cefazolin in pharmaceutical formulation, human urine and plasma.

Exposure to paraquat associated with periodontal disease causes motor damage and neurochemical changes in rats

Exposure to paraquat is possibly involved with the development of several conditions, including neurodegenerative diseases, such as Parkinson's disease (PD). This condition is mainly characterized by the loss of dopaminergic neurons in the nigrostriatal pathway and the development of classical motor symptoms. Etiology includes exposure to environmental factors, such as the paraquat exposure, and inflammatory diseases may exacerbate paraquat neurotoxicity. The aim of the study was to investigate whether the exposure to paraquat associated with the presence of periodontal disease is able to induce motor and biochemical changes in rats similar to that observed in PD. Adult male Wistar rats were sent to ligature. After 48 h, they were sent to daily treatment paraquat (1 mg/kg/day; 2 mL/kg; intragastric) or vehicle for 4 weeks. Twenty-four hours after the last administration, the open field test was performed. The rats were euthanized and the left hemimandibles and striatum were dissected for the analysis of dopaminergic and inflammatory markers. Only the combination of periodontal disease model plus paraquat exposure induced motor impairments. Remarkably, the paraquat exposure increased the ligature-induced alveolar bone loss in hemimandibles. Moreover, only the combination of periodontal disease and paraquat exposure induced the loss of dopaminergic neurons and astrocyte activation in the striatum.

Supramolecular Solvent-Based Liquid Phase Microextraction Combined with Ion-Pairing Reversed-Phase HPLC for the Determination of Quats in Vegetable Samples

In this study, we used anion supramolecular solvent (SUPRAS) prepared from a mixture of an anionic surfactant, sodium dodecyl sulfate (SDS), and a cationic surfactant, tetrabutylammonium bromide (TBABr), as the extraction solvent in liquid phase microextraction (LPME) of paraquat (PQ) and diquat (DQ). The enriched PQ and DQ in the SUPRAS phase were simultaneously analyzed by ion-pairing reversed-phase high performance liquid chromatography. PQ and DQ were successfully extracted by LPME via electrostatic interaction between the positive charge of the quats and the negative charge of SUPRAS. PQ, DQ, and ethyl viologen (the internal standard) were separated within 15 min on a C18 column, with the mobile phase containing 1-dodecanesulfonic acid and triethylamine, via UV detection. The optimized conditions for the extraction of 10 mL aqueous solution are 50 μL of SUPRAS prepared from a mixture of SDS and TBABr at a mole ratio of 1:0.5, vortexed for 10 s at 1800 rpm, and centrifugation for 1 min at 3500 rpm. The obtained enrichment factors were 22 and 26 with limits of detection of 1.5 and 2.8 µg L^-1 for DQ and PQ, respectively. The precision was good with relative standard deviations less than 3.86%. The proposed method was successfully applied for the determination of PQ and DQ in vegetable samples and recoveries were found in the range of 75.0% to 106.7%.

Ionic Liquid Chelate Extraction Behavior of Trivalent Group 13 Metals into 1-Alkyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imides Using 8-Quinolinol as Chelating Extractant

Ionic liquid (IL) chelate extraction behavior of trivalent Group 13 metals including aluminum(III), gallium(III) and indium(III) with 8-quinolinol (HQ) was investigated using three 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C_nmimTf₂N, n = 2, 4 and 8) ILs. Although the three extraction systems showed similar extraction selectivity among the metals, the extractability order for the metals among the extraction systems was C₈mimTf₂N > C₄mimTf₂N > C₂mimTf₂N, which was the same as the order of hydrophobicity in the IL cation. Only the neutral 1:3 complex species was extracted in use of more-hydrophobic C₈mimTf₂N, whereas use of less-hydrophobic C₄mimTf₂N and C₂mimTf₂N resulted in competitive extraction of neutral 1:3 and cationic 1:2 complexes. For each of the metals, in addition, similar extraction constants were obtained in these three extraction systems.