Highly sensitive and selective determination of uranium in natural waters through a novel solidified floating organic drop microextraction method coupled with spectrophotometric determination

Abstract

Ultra trace amounts of uranyl ions was extracted using a reliable, simple and selective solidified floating organic drop microextraction (SFODME) method and determined by UV-Vis spectrophotometry. Di-2-ethylhexylphosphoric acid (HDEHP) was applied as complexing ligand during the microextraction process and Arsenazo III (AIII) was used as the chromogenic reagent through spectrophotometric determination. The effects of the important experimental parameters on UO 2 -AIII complex formation and color development were studied. Other important experimental parameters affected microextraction recovery, such as; type and volume of extracting organic solvent, acid concentration of sample solution, ligand concentration, stirring rate, extraction time and temperature, and salt addition effect were also evaluated and optimized. Under the optimized conditions a linear response was obtained over the range of 0.8-75 ng mL -1 for uranyl ions. The interfering effect of some foreign ions on extraction and determination of uranyl ions were also investigated. Limit of detection, relative standard deviation and enrichment factor of the proposed SFODME-UV method were obtained as 0.1 ng mL -1 , 3.7% and 125 for uranyl ions, respectively. The proposed method was applied successfully for the extraction and determination of uranyl ions in natural water samples. Good agreement was observed between the results of proposed SFODME method and those reported by official standard method.

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

“…Gentle stirring or agitation can aid in the dispersion of solidified droplets and improve mass transfer between the sample matrix and the extraction phase. 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 characteristics presence of dissolved salt in water can modify the physical features, the addition of salt causes a slight decrease in extraction efficiency. On the other hand, the process of salting out can lead to an increase in extraction efficiency [35]. Salt addition can alter the density of an aqueous solution, as a saturated salt solution hinders the free movement of the analyte which may affect the position of an organic solvent after extraction [40].…”

A new optical sensor for selective quantitation of uranium by the immobilization of arsenazo III on an agarose membrane

“…[8][9][10] Several analytical methods such as cloud-point extraction (CPE), dispersive liquid-liquid microextraction (DLLME) and solid phase extraction (SPE) have been used for the determination of uranium. [11][12][13] However, these methods are usually multi step and time consuming. Selective optical sensors (optodes) can be used for the simultaneous preconcentration and quantication of target compounds and have been also introduced for the determination of uranium in natural water samples.…”

Spherical agarose-coated magnetic nanoparticles functionalized with a new salen for magnetic solid-phase extraction of uranyl ion

“…However, these techniques are high cost with restricted accessibility. Arsenazo III, a soluble reagent in water, is a well-known photometric indicator for determination of uranyl ion [12]. This technique is easy and low cost with high precision and accuracy and satisfactory detection limit.…”

“…In order to increase the sensitivity of determination of uranium, a number of methods such as dispersive liquid-liquid microextraction (DLLME), cloud point extraction (CPE) and solid-phase extraction (SPE) have been used for the preconcentration of uranyl [12][13][14][15][16]. Magnetic solid-phase extraction (MSPE) is a useful technique for the extraction in various matrices [17].…”