Preconcentration of Cadmium in Environmental Samples by Cloud Point Extraction and Determination by FAAS

F. Sánchez Rojas,C. Bosch Ojeda,J. M. Cano Pavón

doi:10.4236/ajac.2010.13016

Abstract

Cloud point extraction (CPE) has been used for the preconcentration of cadmium, after the formation of a complex with 1, 5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH), and further determination by flame atomic absorption spectrometry (FAAS) using Triton X-114 as surfactant. The main factors affecting the CPE, such as concentration of Triton X-114 and DPTH, pH, equilibration temperature and incubation time, were optimized for the best extract efficiency. Under the optimum conditions i.e., pH 5.4, [DPTH] = 6x10-3%, [Triton X-114] = 0.25% (v/v), an enhancement factor of 10.5 fold was reached. The lower limit of detection (LOD) obtained under the optimal conditions was 0.95 μg L?1. The precision for 8 replicate deter- minations at 20 and 100 μgL?1 Cd were 2.4 % and 2 % relative standard deviation (R.S.D.). The calibration graph using the preconcentration method was linear with a correlation coefficient of 0,998 at levels close to the detection limit up to at least 200 μgL?1. The method was successfully applied to the determination of cadmium in water, environmental and food samples and in a BCR-176 standard reference material.

Highlights

Monitoring the presence of toxic trace elements in diverse matrices is an extremely important task to evaluate occupational and environmental exposure
We report on the results obtained in a study of the Cloud point extraction (CPE) of Cd2+, after the formation of a complex with DPTH using Triton X-114 as surfactant followed by analysis by flame atomic absorption spectrometry (FAAS)
10 mL analyte solution containing cadmium, 1mL buffer solution pH 5.4, DPTH 6 × 10-3 % and 0.25% (v/v) Triton X-114 was kept in a thermostated bath at 50oC for 30 min

Summary

Introduction

Monitoring the presence of toxic trace elements in diverse matrices is an extremely important task to evaluate occupational and environmental exposure. In this sense, cadmium is one of the most toxic elements and accumulates in humans mainly in the kidneys and liver and is classified as a prevalent toxic element with biological half-life in the range of 10-30 years [1]. Spectrometric techniques for the analysis of trace cadmium have developed rapidly due to the increasing need for accurate measurements at extremely low levels of this element in diverse matrices. An interesting revision presented by Ferreira et al [4] covers separation and preconcentration procedures, and considers the features of the application with several spectrometric techniques

Methods

Results

Conclusion