Application of l-cystine modified zeolite for preconcentration and determination of ultra-trace levels of cadmium by flame atomic absorption spectrometry

• Low cost, simple and very sensitive SPE-FAAS method is applied for Cd2+ analysis.
• High preconcentration factorand sub-ppb detection limit was obtained.
• The method included simple preparation steps and rapid extraction.
• The optimized methods can be applied to the determination of Cd2+ in real samples.

A very convenient, sensitive and precise solid phase extraction (SPE) system was developed for enrichment and determination of ultra-trace of cadmium ion in water and plant samples. This method was based on the retention of cadmium(II) ions by l-cystine adsorbed in Y-zeolite and carry out in a packed mini-column. The retained cadmium ions then were eluted and determined by flame atomic absorption spectrometry. The scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy techniques were applied for the characterization of cystine modified zeolite (CMZ). Some experimental conditions affecting the analytical performance such as pH, eluent type, concentration of sample, eluent flow rate and also the presence of interfering ions were investigated. The calibration graph was linear within the range of 0.1–7.5 ng mL−1 and limit of detection was obtained 0.04 ng mL−1 with the preconcentration factor of 400. The relative standard deviation (RSD) was obtained 1.4%, indicating the excellent reproducibility of this method. The proposed method was successfully applied for the extraction and determination of cadmium(II) ion in black tea, cigarette’s tobacco and also various water samples.