Ligandless-solidified floating organic drop microextraction method for the preconcentration of trace amount of cadmium in water samples.

In this article, a new ligandless solidified floating organic drop microextraction (LL-SFODME) method has been developed for preconcentration of trace amount of cadmium as a prior step to its determination by flow injection-flame atomic absorption spectrometry (FI-FAAS). The methodology is based on the SFODME of cadmium with 1-dodecanol in the absence of chelating agent. Several factors affecting the microextraction efficiency, such as, pH, sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate and temperature were investigated and optimized. Under optimized experimental conditions an enhancement factor of 205 was obtained for 100mL of sample solution. The calibration graph was linear in the range of 1.0-25.0 ng mL(-1), the limit of detection (3s) was 0.21 ng mL(-1) and the limit of quantification (10s) was 0.62 ng mL(-1). The relative standard deviation (RSD) for 10 replicate measurements of 10 ng mL(-1) cadmium was 4.7%. The developed method was successfully applied to the extraction and determination of cadmium in standard and several water samples and satisfactory results were obtained.

Combination of cloud point extraction and flame atomic absorption spectrometry for preconcentration and determination of nickel and manganese ions in water and food samples.

A simple, rapid, inexpensive, and nonpolluting cloud point extraction (CPE) technique has been improved for the preconcentration and determination of nickel and manganese. After complexation with p-nitrophenylazoresorcinol (Magneson I), the analytes could be competitively extracted in a surfactant octylphenoxy polyethoxyethanol (Triton X-114), prior to determination by flame atomic absorption spectrometry (FAAS). The effects of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on CPE were studied. Under the optimum conditions, preconcentration of a 25 mL sample solution permitted the detection of 2.7 ng mL(-1) Ni(2+) and 2.9 ng mL(-1) Mn(2+) with enrichment factors of 17 and 19 for Ni(2+) and Mn(2+), respectively. The developed method was applied to the determination of trace nickel and manganese in water and food samples with satisfactory results.