Application of cloud point preconcentration and flame atomic absorption spectrometry for the determination of cadmium and zinc ions in urine, blood serum and water samples

Abstract

Recebido em 27/3/12; aceito em 20/10/12; publicado na web em 21/2/13 A simple, sensitive and selective cloud point extraction procedure is described for the preconcentration and atomic absorption spectrometric determination of Zn 2+ and Cd 2+ ions in water and biological samples, after complexation with 3,3',3",3'"-tetraindolyl (terephthaloyl) dimethane (TTDM) in basic medium, using Triton X-114 as nonionic surfactant. Detection limits of 3.0 and 2.0 μg L -1 and quantification limits 10.0 and 7.0 μg L -1were obtained for Zn 2+ and Cd 2+ ions, respectively. Relative standard deviation was 2.9 and 3.3, and enrichment factors 23.9 and 25.6, for Zn 2+ and Cd 2+ ions, respectively. The method enabled determination of low levels of Zn 2+ and Cd 2+ ions in urine, blood serum and water samples.

Selective and Sensitized Spectrophotometric Determination of Cr(III) Ion using 2-(Phenyl)-4,5-di(4-methoxyphenyl)imidazole, Ligand for Speciation of Chromium Ion in Triton X-100 as Surfactant

“…42 filter paper into a 250 mL calibrated flask, after adjustment of pH to desired value, it was diluted to mark with de-ionized water. Amount of Cr(III) ion was found by standard addition method 28 for all of real and synthetic samples.…”

Recent advances in applications of nanomaterials for sample preparation

“…The external layer of BSA modified on CNTs could exclude proteins through electrostatic repulsion when sample pH was higher than the pI of both BSA and serum proteins, while setting no restriction on the access of positively charged cadmium ions, with which the interference of serum proteins in cadmium analysis was eliminated. With the aid of protein elimination by RACNTs, a lower limit of detection (LOD) of 0.24 μg L -1 for cadmium in blood was obtained compared with the results from other pretreatment methods, such as cloud point extraction (2.0 μg L -1 ) [23] and acid extraction (14.0 μg L -1 ) [24]. In the analysis of organic pollutants in real samples, functionalized CNPs could be utilized to realize either target extraction [25] or matrix clean-up [26].…”

Cloud point extraction procedure for preconcentration and determination of lead(II) ions using triton X-100 at room temperature

“…However, these conventional separation methods are usually time consuming and require relatively large amounts of high purity solvents which are often toxic and a special disposal method is needed (10). Cloud point extraction (CPE) is an attractive technique in recent decade, due to its several advantages such as low cost, safety (reduction of solvent consumption and exposure to toxic organic solvents), less stringent requirements for separation, higher preconcentration factor, easier manipulation and the duration of the procedure (11). Also, the attachment to analytical instruments such as graphite furnace and flame atomic absorption spectrometry is easier comparing to other techniques (12).…”

“…The CPE method has important practical application for separation and refocuses the analyte as a step before its determination, and after its formation in the water of a poorly soluble complex. CPE experiments reported previously (10)(11)(12)(13)(14) are based on behavior of nonionic surfactants, at their respective ″cloud point temperature″ when formation of ″surfactant-rich phase″ enables preconcentration of analyte. Nonionic surfactant solutions become turbid at their ″cloud point temperature″ and, consequently the micellar solution separates into two phases: a surfactant-rich phase and an essentially bulk aqueous phase (15).…”

“…The principles and applications of CPE have been discussed in various interesting reviews (16)(17)(18). Among nonionic surfactants, Triton X-114 was applied widely due to its lower cloud point temperature, close to room temperature (23 °C), which simplify the extraction procedure in terms of shorter duration of heating (or no heating) and easier experiment maintaining (11,12,15,19). However, for nonionic surfactants with higher cloud point temperatures, such as Triton X-100 (69 °C), it is possible to simplify the extraction procedure by decreasing the cloud point temperature through using synergic reagents (20,21) or adding electrolytes (″salting-out″).…”