β-Cyclodextrin-grafted magnetic graphene oxide nanocomposites in ultrasound-assisted dispersive magnetic solid-phase extraction for simultaneous preconcentration of lead and cadmium ions

Fe3O4-SiO2-MIL-53 (Fe) nanocomposite for magnetic dispersive micro-solid phase extraction of cadmium (II) at trace levels prior to HR-CS-FAAS detection

A magnetic metal-organic framework Fe3O4-SiO2-MIL-53 (Fe) nanocomposite was synthesized for magnetic dispersion micro-solid phase extraction (M-d-µSPE) of cadmium in water, spice, chocolate, tea, and tobacco samples prior to the detection by flame atomic absorption spectrometry. Fe3O4-SiO2-MIL-53 (Fe) nanocomposite fabricated using the solvothermal technique was characterized using a field emission scanning electron microscope and X-ray diffraction. The extraction efficiency of the method was improved by optimizing the experimental factors. After optimization, the linearity range for Cd (II) was 4.3-500 µgL-1. The limits of detection and quantification were 1.3 and 4.3 µgL-1, respectively. The presented magnetic dispersion-micro solid phase extraction method was applied to Cd (II) analysis in food and some environmental samples.

A rapid magnetic-based purification of Cd2+ and Pb2+ prior to portable electrochemical determination for grain

How to quickly separate and detect cadmium (Cd²⁺) and lead (Pb²⁺) from solid samples is a difficult problem that needs to be solved. For this, Fe₃O₄@agarose@iminodiacetic acid (IDA) was synthesized and used for rapid purification of Cd²⁺ and Pb²⁺. This material can remove complex matrix interference completely within a short time of 15 min. The mechanism of the adsorption kinetics fit well to a pseudo-second-order model. A portable screen-printed electrodes (SPEs)-based electrochemical detection platform was established. After coupling with the pretreatment, the whole detection process only took within 30 min. The limits of detection (LOD) were ten times lower than those of the Codex general standard, with values of 0.02 and 0.01 mg/kg for Pb²⁺ and Cd²⁺, respectively. The recoveries ranged from 84.1% to 109.7% in naturally contaminated grain, in good agreement with the ICP-MS, demonstrating great prospects for the rapid screening and monitoring of Cd²⁺ and Pb²⁺ in grain.

Insights into brewed tea waste as a green and low-priced adsorbent for solid-phase extraction of Cd(II) ions: isotherm, kinetic, and artificial neural network approach

In the present research, brewed tea waste (BTW) was utilized as a green, low-priced, and abundant adsorbent for separation/preconcentration of Cd(II) ions through solid-phase extraction method from water and foods for the first time. BTW was applied as a natural adsorbent, without using any chelating agent to bind Cd(II) ions or any chemical reagent for its modification. A three-layer artificial neural network model using backpropagation algorithm was utilized to explicate a prediction model for the extraction performance of Cd(II) ions by selecting the input parameters as solution pH, quantity of BTW, sample volume, eluent concentration and volume, and equilibrium time for desorption. The preconcentration factor, relative standard deviation, and detection limit were attained as 100, 3.03%, and 0.56 µg L−1, respectively. It was decided that the Langmuir isotherm model is acceptable to characterize the retention of Cd(II) ions on BTW. This result pointed out that the active binding sites on the BTW surface are homogeneously distributed. Adsorption capacity of BTW was achieved as 41.5 mg g−1 which is higher than several expensive and difficult-to-prepare adsorbents. Adsorption kinetics was elucidated by pseudo-second order kinetic model. After confirmed the accuracy of the method with spike/recovery studies, it was employed for Cd(II) determination in water (stream and sea water) and food (eggplant, lettuce, parsley, apple, and apricot) samples with high accuracy. The inferences of the study proved that the BTW offers a magnificent application prospect in the extraction of Cd(II) ions.