A new nanobiosorbent based on cross-linked chitosan magnetic beads modified with methionine-glutaraldehyde schiff’s base (MG-Chi/Fe₃O₄) was synthesised for removing Cu(II), Pb(II) and Cd(II) from wastewater samples. Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) have been applied to characterise nanobiosorbent. A variety of parameters influencing uptake behaviours of the metal ions, including pH, adsorbent dose, contact time, initial concentration of the metal ions and desorption conditions were examined and optimised. The pH ZPC of MG-Chi/Fe₃O₄ was found to be 4.0. Freundlich and Langmuir isotherm models were applied to estimate adsorption mode. The equilibrium data were well fitted with the Langmuir isotherm model. The maximum adsorption capacities for Cu(II), Pb(II), and Cd(II) were 172.4, 175.4 and 163.9 mg g⁻¹, respectively. The adsorption kinetics fitted better with the pseudo-second-order model indicating that chemical adsorption is the rate-limiting step in the adsorption process. The adsorbent (MG-Chi/Fe₃O₄ nanobiosorbent) performance is maintained for at least 4 adsorption-desorption cycles. Finally, MG-Chi/Fe₃O₄ nanobiosorbent exhibited high potential to remove the metal ions from Iran Khodro’s wastewater.

Trace amounts of Cu (II), Pb (II), and Cd (II) in a wastewater sample were preconcentrated with a novel cross‐linked magnetic chitosan modified with a new synthesised methionine‐glutaraldehyde Schiff's base (MG‐Chi/Fe ₃ O ₄ ) as a dispersive solid‐phase extraction (DSPE) adsorbent. The adsorbed metal ions were then eluted with a specific volume of suitable solution and determined by flame atomic absorption spectrometry (FAAS). Various parameters affecting the extraction efficiency of the metal ions were investigated and optimised, including pH, amount of adsorbent, extraction time, type and volume rate of eluent, elution time, sample volume, and effect of interfering ions. The adsorption kinetics are more consistent with the pseudo‐second order model. The results were statistically interpreted and the analytical performance of the proposed method was found to have preconcentration factors of 55, 60, and 50 μg L ⁻¹ for Cu(II), Pb(II), and Cd(II), respectively, limits of detection were 0.22, 0.24, and 0.10 μg L ⁻¹ for Cu(II), Pb(II), and Cd(II), respectively, with a relative standard deviation (1.5%‐2.8 %), and the liner range was 5–1000 for Cu(II) and Pb(II) and 2.5–1000 for Cd(II). It was concluded that this method was suitable for successful simultaneous determination of Cu(II), Pb(II), and Cd(II) in industrial wastewater samples.

A fast and simple method for preconcentration of Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cu²⁺ and Co²⁺ from natural water samples was developed. The metal ions were complexed with sodium diethyldithiocarbamate (Na‐DDTC), then adsorbed onto octadecyl silica membrane disk, recovered and determined by FAAS. Extraction efficiency, influence of sample volume and eluent flow rates, effects of pH, amount of Na‐DDTC, nature and amount of eluent for elution of metal ions from membrane disk, break through volume and limit of detection have been evaluated. The effect of foreign ions on the percent recovery of heavy metal ions has also been studied. The limit of detection of the proposed method for Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cu²⁺ and Co²⁺was found to be 2.03, 0.47, 3.13, 0.44, 1.24 and 2.05 ng·mL⁻¹, respectively. The proposed (DDTC) method has been successfully applied to the recovery and determination of heavy metal ions in different water samples.

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. This review covers separation and preconcentration procedures, and consider the features of the their application with several spectrometric techniques. The use of an appropriate sample handling technique is a must in an analysis of trace Cadmium in water. The efforts to use a solid phase for the recovery of analytes from a water matrix prior to their detection have a long history. The initial experimental applications of SPE resulted in widespread use of this technique in current water analysis and also to adoption of SPE into standardized analytical methods. Cadmium is recognized worldwide as a poisonous metal. Thus, the determination of this element is often required in environmental, biological, food and geological samples. However, these analyses are difficult because such samples contain relatively low concentrations of Cadmium, which fall below the detection limit of conventional analytical techniques such as flame atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry. Several preconcentration procedures to determine Cadmium have therefore been devised, involving separation techniques such as liquid–liquid extraction, solid phase extraction, coprecipitation and cloud point extraction. Review of preconcentration procedures for determining Cadmium using spectroanalytical techniques. A brief overview of the history of the use of SPE in trace Cadmium analysis of water is given in presented paper.