In this work, a new method based on dispersive liquid–liquid microextraction (DLLME) preconcentration using tetrachloromethane (CCl₄) as extraction solvent was proposed for the spectrophotometric determination of cadmium and copper in water and food samples. The influence factors relevant to DLLME, such as type and volume of extractant and disperser solvent, concentration of chelating reagents, pH, salt effect, were optimized. Under the optimal conditions, the limits of detection for cadmium and copper were 0.01ng/L and 0.5μg/L, with enhancement factors (EFs) of 3458 and 10, respectively. The tremendous contrast of EFs could come from the different maximum absorption wavelength caused by the different extraction acidity compared with some conventional works and the enhancement effect of acetone used as dilution solvent during the spectrophotometric determination. The proposed method was applied to the determination of water and food samples with satisfactory analytical results. The proposed method was simple, rapid, cost-efficient and sensitive, especially for the detection of cadmium.

A simple, fast and cheap method for monitoring copper and nitrate in drinking water and food products using newly developed solid contact ion-selective electrodes is proposed. Determination of copper and nitrate was performed by application of multiple standard additions technique. The reliability of the obtained results was assessed by comparing them using the anodic stripping voltammetry or spectrophotometry for the same samples. In each case, satisfactory agreement of the results was obtained, which confirms the analytical usefulness of the constructed electrodes.

This study reports a simple, rapid and greener method based on ultrasound assisted-cloud point extraction coupled with inductively coupled plasma-optical emission spectroscopy (ICP-OES) for preconcentration and determination of antimony (Sb), tin (Sn) and thallium (Tl) in food and water samples. Factors affecting the preconcentration procedure were optimized using fractional factorial design and response surface methodology based on Box-Behnken design. Under optimum conditions, the calibration graphs were linear over the concentration range of 0.023–700 μg L−1 with correlation coefficients up to 0.9994, the limits of detection ranged from 0.007–0.010 μg L−1, the limits of quantification were from 0.023 to 0.033 μg L−1 and the relative standard deviations (n = 15) were between 1.3% and 4.1%. In addition, the preconcentration factors were found to be 150, 145 and 160 for Sb, Sn and Tl, respectively. Finally, the developed method was successfully applied in various food and water samples as well as certified reference materials for rapid determination of Sb, Sn and Tl.

A simple and efficient determination of curcumin in water and food samples based on the combination of dispersive liquid–liquid microextraction (DLLME) and spectrophotometric estimation has been described. The effects of DLLME effective parameters [extraction solvent (CHCl₃), disperser solvent (ethanol), pH, centrifugation time, and KCl concentration] were optimized via central composite design (CCD) and response surface methodology (RSM) and desirability function (DF) using STATISTICA. At optimum condition specified as 150 μL of chloroform, 900 μL of ethanol, pH = 4.0, and 4 min of centrifugation time in the absence of any salt, a linear calibration graph in the range of 10–2000 ng mL⁻¹ of curcumin with R ² = 0.99942 (n = 6) confirms good applicability of the method for quantification of analytes over a wide range of analytes. The reasonable limit of detection (LOD) and quantification (LOQ) (0. 23 and 0.78 ng mL⁻¹, respectively) makes it suitable for trace analysis. Good relative standard deviation [1.16–2.3 % (n = 12)] and high enrichment factor (EF) 2182.04 are a good remark of the present method. Curcumin with relative standard deviation (RSD) less than 3 % (n = 4) and recoveries in the range 91.76–100 % can be successfully quantified in different real samples.

Herein, a novel Cu/CuFe₂O₄@iron-based metal-organic framework 88 A (Cu/CuFe₂O₄@MIL-88A(Fe)) was developed through a scalable hydrothermal strategy for the magnetic dispersive solid-phase extraction of chlorpyrifos and phosalone from water, fruit juice, and vegetable samples prior to corona discharge ion mobility spectrometry analysis. The resulting nanocomposite was characterized in detail, and thus the investigation indicated that the magnetic nanocomposite had good adsorption capacity, high surface area, dispersion, and superparamagnetic properties. In addition, the fabricated sorbent provided different interactions with the target analytes, (hydrogen bonding, hydrophobic contacts, and π-π stacking interactions) resulting in the improvement of extraction efficiency. The applied method based on Cu/CuFe₂O₄@ MIL-88A(Fe) was validated by investigating the affecting parameters, including the amount of magnetic nanocomposite (10.0 mg), sample pH (7.0), salt content (7.5 % w/v), extraction time (5 min), type of elution (150 μL of methanol), and desorption time (2 min). The linearity of the method was found to be in the range of 0.6–300.0 ng mL⁻¹ and 1.5–500.0 ng mL⁻¹, for chlorpyrifos and phosalone with the coefficient of determination of ≥0.9991. The limits of detections (LODs) of 0.2 and 0.5 ng mL⁻ ¹ were obtained for the determination of chlorpyrifos and phosalone, respectively. The relative standard deviation values (RSDs %) were calculated in the range of 4.4 %–6.1 % (intra-day, n = 5) and 6.3 %–8.0 % (inter-day, n = 3) for three days. Ultimately, the developed method was successfully applied for the extraction of the desired analytes from various spiked samples with acceptable recoveries (88.3–100.4 %).