Preconcentration of Gadolinium Ion by Solidification of Floating Organic Drop Microextraction and Its Determination by UV-Vis Spectrophotometry

Abstract

A solidified floating organic drop microextraction (SFODME) combined with UV-Vis spectrophotometry was applied for preconcentration and determination of Gd(III). In this study, Morin (3, 5, 7. 2', 4' pentahydroxy flavone) as a suitable ligand and 1-Dodecanol as extraction solvent were used. Following the extraction Gd-Morin complex, the extraction solvent was transported to a spectrophotometer for determination of Gadolinium ion at the absorption wave length of 440 nm. The main affecting factors in the performance of SFODME such as pH, concentration of Morin, extraction time, stirring rate and sample volume were investigated and optimized. Under the optimum conditions, the enrichment factor of 23, linear dynamic range of 80-900 µg L -1 with correlation of determination (R 2 >% 99) and limit of detection of 172µg L -1 were obtained for determination of Gd(III). The relative standard deviation (n = 5) for 150 µg L −1 of Gd(III) (sample volume 4.0mL) was ±2.17%. The method was successfully applied for preconcentration and determination of Gd(III) in water samples.

Recent overview of microextraction of metal ions and pharmaceuticals by solidified floating organic drop microextraction techniques

“…When the organic solvent is solidified, by using a spatula the extraction solution is collected in a test tube, and the melted organic solvent is used for the determination of analyte [20]. Due to its efficient merits, SFODME is a simple, quick, and low‐cost technique where the extraction is done up to a small volume (µL) of an extractant at a melting point near room temperature (10–30°C) [19, 21, 22]. A systematic procedure has been illustrated in Figure 4.…”

“…According to the convective‐diffusive mass transfer theory, stirring is a crucial parameter in extraction methods for improving the extraction dynamics [35]. The rate of stirring has a direct impact on droplet characteristics and mass transfer, in the SFODME method very high stirring rate can generate splatter and decrease the required time to achieve the equilibrium between the droplet and the sample solution [21]. The aqueous‐phase mass‐transfer coefficient increases with increasing the stirring rate, various studies showed that the effective stirring rate for various metal ions is in the range of 300–1200 rpm [21, 32, 34, 36].…”

“…The rate of stirring has a direct impact on droplet characteristics and mass transfer, in the SFODME method very high stirring rate can generate splatter and decrease the required time to achieve the equilibrium between the droplet and the sample solution [21]. The aqueous‐phase mass‐transfer coefficient increases with increasing the stirring rate, various studies showed that the effective stirring rate for various metal ions is in the range of 300–1200 rpm [21, 32, 34, 36]. It is observed that a higher stirring rate results in lower extraction efficiency, mostly due to the loss of a floating solvent drop which is difficult to collect and results in organic solvent loss [34].…”

“…The effect of salt concentrations and ionic strength has been investigated with SFODME, the movement rate of the target analytes can interfere potentially with the presence of dissolved salts in water and alter the characteristic physical properties of Nernst diffusion film and decrease the rate of diffusion [21, 38, 39]. The characteristics presence of dissolved salt in water can modify the physical features, the addition of salt causes a slight decrease in extraction efficiency.…”