Development of a double monitoring system for the determination of Cr(VI) in different water matrices by HPLC-UV and digital image-based colorimetric detection method with the help of a metal sieve-linked double syringe system in complexation.

This study reports a cheap, efficient, sensitive, and simple double monitoring analytical method for trace determination of Cr(VI), which is toxic and harmful even at very low concentrations. A metal sieve-linked double syringe (MSLDS) system was used to help the formation of chromium complex (Cr-diphenyl carbazide, DPC) subsequently determined by high-performance liquid chromatography-ultraviolet (HPLC-UV) and digital image-based colorimetry (DIC) systems. The metal complex was eluted through a Phenomenex-Aqua C18 with a mobile phase comprising of 50 mM ammonium formate solution (pH 4.0):acetonitrile (78:22, v/v) and detected by the UV detector at the wavelength of 581 nm. Under their optimum conditions, the HPLC-UV and DIC systems exhibited good linearity in ranges of 10-500 µg L-1 and 100-1000 µg L-1, respectively. The percent relative standard deviations (RSD%s) calculated for the lowest concentrations of both systems fell below 10%, and this confirmed good repeatability for replicate measurements. The accuracy of the proposed methods was evaluated by performing spike recovery experiments on wastewater, river water, and tap water samples. The calculated recovery results were in the range of 81.5-105.5% for HPLC-UV system and 93.8-111.1% for the DIC system. These results indicate that the proposed methods are suitable for routine Cr(VI) determination in terms of their rapidness, simplicity, good repeatability, and low cost.

Development of a metal sieve-linked double syringe liquid phase microextraction method for the determination of copper in olive leaf extract samples by flame atomic absorption spectrometry.

This work reports the development of a simple, sensitive and low-cost analytical method for the trace determination of copper. A metal sieve-linked double syringe liquid phase microextraction method was used to preconcentrate copper into measurable quantities for FAAS system. The pressurized mixing offered by the automated syringe system and the sieve connector enhanced surface area for analyte and extraction solvent interaction, this significantly increased the extraction efficiency for copper. There was therefore no need for auxiliary organic solvents as disperser solvents for the extractant dichloromethane. The limits of detection and quantification, linear dynamic range and percent relative standard deviation values calculated for copper under optimum conditions of the method were 1.5 and 5.1 µg L-1, 5.0-500 µg L-1 and 8.4%, respectively. The developed method was successfully employed to determine copper (0.75-8.06 mg kg-1) in unspiked olive leaf samples.

A basic and effective liquid phase microextraction with a novel automated mixing system for the determination of cobalt in quince samples by flame atomic absorption spectrometry.

A new, green, and simple liquid-phase microextraction method namely sieve conducted two syringe-based pressurized liquid-phase microextraction methods was combined with flame atomic absorption spectrometry for the preconcentration and determination of cobalt. For this aim, a novel automated syringe mixing system was developed to be used in the developed extraction procedure. Two syringes were connected to each other by an apparatus having six holes to produce efficient dispersion of the extractant. The pressure created between the two syringes by the forward and backward movements of the syringe plungers created an efficient dispersion of the extractant. In the present study, ligand as complexing agent was synthesized in our laboratory. Limits of detection and quantification were determined to be 1.8 and 6.0 µg L-1, respectively. A 33.7-fold enhancement in detection power was obtained with the developed method. Method was effectively applied for the determination of cobalt in quince samples.