Ultra-Trace Determination of Copper and Silver in Environmental Samples by Using Ionic Liquid-Based Single Drop Microextraction-Electrothermal Atomic Absorption Spectrometry

A sensitive, selective and effective ionic liquid-based single drop microextraction technique was\ud developed by using ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate, C6MIMPF6, coupled\ud with electrothermal atomic absorption spectrometry (ETAAS) for the determination of copper and silver in\ud environmental samples. Dithizone was used as chelating agent. Several factors that influence the\ud microextraction efficiency and ETAAS signal, such as pH, dithizone concentration, extraction time, amounts of\ud ionic liquid, stirring rate, pyrolysis and atomization temperature were investigated and the microextraction\ud conditions were established. In the optimum experimental conditions, the detection limits (3 s) of the method\ud were 4 and 8 ng L-1 and corresponding relative standard deviations (0.1 μg L-1, n = 6) were 4.2% and 4.8% for\ud Ag and Cu, respectively. The developed method was validated by analysis of a certified reference material and\ud applied to the determination of silver and coppe

Design and construction of ion-selective electrode based on a new Schiff base and its application in determination of copper(II) ions

51-56A copper(II) selective sensor has been made from polyvinyl chloride matrix membrane based on the carrier, 2-(5-bromo-2-hyroxybenzylidineamino) pyridine 3-ol as an ionophore, ortho-nitrophenyl octyl ether (o-NPOE) as mediator solvent and sodium tetraphenylborate (NaTPB) as additive. The best performance is presented by membrane of composition of ionophore (Schiff base):PVC:o-NPOE:NaTPB of 3:33:63:1 (by weight). The membrane potential response is linear in the concentration range of 1.0×10-7 to 1.0×10-2 M with the Nernstian slope of 29.5±0.5 mV per decade of Cu2+ and a detection limit of 7.4×10-8 M. The response time of the sensor is very short; less than 10 s, and it can be used for at least 8 weeks without any difference in potential. The proposed copper(II) selective electrode displays excellent selectivity towards alkali, alkaline earth and transition metal ions and can be used in the pH range of 4-7. It has been successfully used as an indicator electrode for the determination of Cu(II) in water samples. The electrode has also been employed as an indicator electrode in titration of Cu2+ with EDTA

N-Propargylamines: versatile building blocks in the construction of thiazole cores

Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines. This review will be helpful in the development of improved methods for the synthesis of natural and biologically important compounds

Vortex assisted solid-phase extraction of lead(II) using orthorhombic nanosized Bi2WO6 as a sorbent

Nanosized single crystal orthorhombic Bi2WO6 was synthesized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The crystal and molecular structure of the sorbent was examined using XRD, Raman, SEM and SEM-EDX analysis. Various parameters affecting extraction efficiency were optimized by using multivariate design. The effect of diverse ions on the extraction also was studied. Lead was quantified by flame atomic absorption spectrometry (FAAS). The recoveries of lead(II) from spiked samples (at a typical spiking level of 200-400 ng.mL(-1)) are >95%. Other figures of merit includes (a) a detection limit of 6 ng.mL(-1), (b) a preconcentration factor of 50, (c) a relative standard deviation of 1.6%, and (d) and adsorption capacity of 6.6 mg.g(-1). The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples