A Sensitive Method for Cadmium Determination Using an On-line Polyurethane Foam Preconcentration System and Thermospray Flame Furnace Atomic Absorption Spectrometry

Abstract

A new sensitive and low cost method for cadmium determination at µg l -1 levels that combines an on-line preconcentration system with the thermospray flame furnace atomic absorption spectrometry technique (TS-FF-AAS) is described in this work. Cadmium is preconcentrated from an acidic medium (pH 2.0) by forming a complex with ammonium Ο,Ο-diethyldithiophosphate (DDTP), which is then adsorbed onto polyurethane foam (PUF). The elution step is performed by using 80% (v/v) ethanol. The effects of the chemical and flow variables associated with the preconcentration were studied, such as the pH of formation of the Cd-DDTP complex, the DDTP concentration, the preconcentration and elution flow rate and the mass of adsorbent. The present method was operated in volume-mode (2 ml) and provided a linear range from 0.4 to 15.0 µg l -1 with a sample throughput of 16 h -1 . The increase of power detection related to TS-FF-AAS by coupling the preconcentration system was confirmed by the enhancement of sensitivity (ca. 5 times), when compared to the value for TS-FF-AAS alone, thus achieving a low detection limit (0.12 µg l -1 ). The accuracy of the method was confirmed from analyses of spiked water samples and by the use of a reference technique (ETAAS). Certified biological materials were also used for the same purpose.

Cloud point extraction for the determination of copper in environmental samples by flame atomic absorption spectrometry

“…The small volume of the surfactant-rich phase obtained with this methodology permits the design of extraction schemes that are simple, cheap, highly efficient, and of lower toxicity to the environment than those extractions that use organic solvents. The CPE phenomenon has been used for the extraction and preconcentration of metal cations [13][14][15][16][17][18][19] after the formation of sparingly water-soluble complexes. CPE has been shown to be an effective sample preconcentration technique for improving sensitivity and selectivity prior to atomic spectrometry.…”

Selective sorbent enrichment of nickel ions from aqueous solutions using a hierarchically hybrid organic-inorganic polymer based on double imprinting concept

“…22 Eight replicates determinations of both 2.0 and 13.0 µg L -1 gave the respective relative standard deviation of 2.67 e 3.37%, respectively. By preconcentrating 20 mL of sample, the experimental enrichment factor of the proposed IIP sorbent, calculated as the ratio between the slopes of analytical curves with and without the enrichment procedure, 23 was found to be 11 fold. Other important analytical parameters for sorbent enrichment were also calculated, such as consumptive index (CI = sample volume/EF) of 1.81 mL and enrichment efficiency (EE), which establishes the sensitivity enhancement using a preconcentration time of 1 min.…”

On-line Determination of Zinc in Water and Biological Samples after Its Preconcentration onto Zincon Anchored Polyurethane Foam

“…12,13 On-line preconcentration procedures are advantageous compared with the off-line batch systems, because they feature low volume sample/reagent consumption, high enrichment factors and high throughputs. 14 Polyurethane foam (PUF) is a pragmatic material for preconcentration and separation of a wide variety of inorganic and organic compounds in different media due to its low cost, high available surface area and cellular structure and stability in acidic or basic media. PUF has been used unloaded or associated to physically immobilized chelating reagents in preconcentration and sampling procedure.…”