Application of Switchable Hydrophobicity Solvents for Extraction of Emerging Contaminants in Wastewater Samples

In the present work, the effectiveness of switchable hydrophobicity solvents (SHSs) as extraction solvent (N,N-Dimethylcyclohexylamine (DMCA), N,N-Diethylethanamine (TEA), and N,N-Benzyldimethylamine (DMBA)) for a variety of emerging pollutants was evaluated. Different pharmaceutical products (nonsteroidal anti-inflammatory drugs (NSAIDs), hormones, and triclosan) were selected as target analytes, covering a range of hydrophobicity (LogP) of 3.1 to 5.2. The optimized procedure was used for the determination of the target pharmaceutical analytes in wastewater samples as model analytical problem. Absolute extraction recoveries were in the range of 51% to 103%. The presented method permits the determination of the target analytes at the low ng mL−1 level, ranging from 0.8 to 5.9 (except for Triclosan, 106 ng mL−1) with good precision (relative standard deviation lower than 6%) using high-pressure liquid chromatography (HPLC) combined with ultraviolet (DAD) and fluorescence (FLR) detection. The microextraction alternative resulted in a fast, simple, and green method for a wide variety of analytes in environmental water sample. The results suggest that this type of solvent turns out to be a great alternative for the determination of different analytes in relatively complex water samples

Electrocatalytic oxidation and voltammetric determination of sulfamethazine using a modified carbon electrode with ionic liquid

© 2018 Sociedad Chilena de Quimica. All rights reserved. A carbon paste electrode was modified with the ionic liquid 1-methyl-3-octyl imidazolium hexafluorophosphate and it was applied for study the electrocatalytic oxidation and voltammetric determination of the drug sulfamethazine. The developed modified electrode was characterized using cyclic voltammetry and scanning electron microscopy. The oxidation of sulfamethazine at the surface of modified electrode occurs at lower potentials than that of an unmodified carbon paste electrode, and both an enhancement of the anodic peak current and a signal narrower and better defined with the modified electrode were observed. Accordingly, a method for the determination of sulfamethazine was developed using differential pulse voltammetry, at pH 11 and with an accumulation time of 3 min. The oxidation of sulfamethazine exhibited a dynamic range between 30 and 300 μg/mL and detection and quantitation limits of 54 and 61 μg/mL, respectively. The

Voltammetric behavior of naratriptan and its determination in tablets

The electrochemical behavior and the analytical application of the selective serotonin agonist naratriptan (N-methyl-3-(1-methyl-4-piperidyl)indole-5-ethanesulfonamide) are presented herein. Naratriptan exhibits an anodic response in aqueous media over a broad pH range (pH 2-12). as determined by differential pulse voltammetry and cyclic voltammetry using glassy carbon electrodes. This response is irreversible in nature, diffusion-controlled and probably caused by the oxidation of the naratriptan indole moiety. The differential pulse voltammetry technique was performed in 0.1 mol L-1 Britton-Robinson buffer (pH = 3), which elicited the most reproducible results. The percentage of naratriptan recovery was 102.1 +/- 1.8%, and the limits of detection and quantitation were 9.5 x 10(-6) and 2.0 x 10(-5) mol L-1, respectively. Selectivity trials revealed that the oxidation signal of the drug was not disturbed by the presence of excipients or degradation products. Thus, we conclude that the method presented herein is useful for the quantification of naratriptan in pharmaceutical drugs and that this method requires no separations or extractions. Finally, this voltammetric method was successfully applied to determine the quantity and the content uniformity of naratriptan in drug tablets. A comparison of this technique to the standard high-performance liquid chromatography technique was conducted at the end of our study

Ionic liquids for improving the extraction of NSAIDs in water samples using dispersive liquid-liquid microextraction by high performance liquid chromatography-diode array-fluorescence detection

A rapid, sensitive and efficient analytical method based on the use of ionic liquids for determination of non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed. High-performance liquid chromatography equipped with a diode array and fluorescence detector was used for quantification of ketoprofen, ibuprofen and diclofenac in tap and river water samples. This new method relies on the use of two ionic liquids with multiple functionalities: one functions as an extraction solvent (1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the other changes the polarity in the aqueous medium (1-butyl-3-methylimidazolium tetrafluoroborate, ([BMIM[BF4]). Factors such as the type and volume of the ILs and dispersive solvent, sample volume, and centrifugation time were investigated and optimized. The optimized method exhibited good precision, with relative standard deviation values between 2% and 3%, for the three NSAIDs. Limits of detection achieved for all of the analytes were between 17 and 95 ng mL(-1), and the recoveries ranged from 89% to 103%. Furthermore, the enrichment factors ranged from 49 to 57. The proposed method was successfully applied to the analysis of NSAIDs in tap and river water samples

Electrocatalytic oxidation and voltammetric determination of sulfamethazine using a modified carbon elctrode with ionic liquid

A carbon paste electrode was modified with the ionic liquid 1-methyl-3-octyl imidazolium hexafluorophosphate and it was applied for study the electrocatalytic oxidation and voltammetric determination of the drug sulfamethazine. The developed modified electrode was characterized using cyclic voltammetry and scanning electron microscopy. The oxidation of sulfamethazine at the surface of modified electrode occurs at lower potentials than that of an unmodified carbon paste electrode, and both an enhancement of the anodic peak current and a signal narrower and better defined with the modified electrode were observed. Accordingly, a method for the determination of sulfamethazine was developed using differential pulse voltammetry, at pH 11 and with an accumulation time of 3 min. The oxidation of sulfamethazine exhibited a dynamic range between 30 and 300 mu g/mL and detection and quantitation limits of 54 and 61 mu g/mL, respectively. The method was applied to the determination of sulfamethazine in a veterinary commercial solution.FONDECYT 115086

HPLC determination of nimesulide in tablets by electrochemical detection

An analytical chromatographic method for the determination of nimesulide in pharmaceutical forms has been developed. The method is based on high performance liquid chromatographic (HPLC) and electrochemical detection. Chromatography was performed on a μBondapak/μPorasil C-18 column (150 min x 3.9 mm I.D.). The mobile phase consisted of pH 3 buffer phosphate-methanol (40:60, v/v) at a flow-rate of 1 mL/min. The analytes were detected by electrochemical detection in the pulse mode at 1200 mV. For comparative purposes both an HPLC with diode array detector and a spectrophotometric method were employed. The results of the recovery study (mean 101.07, rsd 1.44) show that HPLC with an electrochemical detection method is adequately precise and accurate and can be recommended for the determination of nimesulide in tablets

Voltammetric behavior of 1,4‐dihydropyridine calcium antagonists

The anodic electrochemical behavior of the five members of the 1,4‐dihydropyridine calcium antagonists family was studied. In all of the studied compounds (nifedipine, nitrendipine, nimodipine, nicardipine, and furaldipine), the oxidation process reveals only one anodic peak due to the twoelectron oxidation of the dihydropyridine ring to form the pyridine derivative compound. The differential pulse voltammetric technique was used for the quantitation of the 1,4‐dihydropyridines in pharmaceutical forms. The voltammetric determination developed here represents a good analytical alternative, because sample preparation is easy (no excipient separation is necessary), is not time consuming, and is adequately accurate and precise. Furthermore, the developed method can be applied as an important tool in photodegradation studies. Copyright © 1994 VCH Publishers, Inc