Designing a simple semi-automated system for preconcentration and determination of nickel in some food samples using dispersive liquid–liquid microextraction based upon orange peel oil as extraction solvent

Europium metal-organic frameworks: Synthesis, characterization, and application as fluorescence sensors for the detection of Cu2+, Ni2+ cations and T3, T4 hormones

The solvothermal approach was used to create a novel Eu metal-organic framework (Eu-MOF) based on 1,4-benzendicarboxylic acid (TPA), 1,10-phenanthroline, and N,N-dimethylformamide (DMF)/H2O. Structural analysis of Eu-MOF, Fluorescence spectrometry, Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDX) mapping, Thermo-gravimetric analysis (TGA), and Single Crystal X-Ray Diffraction (PXRD) methods. Using the fluorescence properties of the synthesized Eu-MOF, its use as a fluorescence sensor in the determination of different analytes, such as organic molecules (T3-T4 hormone, ascorbic acid, and glucose) and metal ions (Na+, K+, Ca2+, Mg2+, Cu2+, Mn2+, Hg2+, Pb2+, Ni2+, Cr3+, Al3+, Fe3+), was investigated. Fluorescence experiments revealed that Cu2+, Ni2+ cations, as well as T3 and T4 hormones, quenched the fluorescence of Eu-MOF. Turn-off luminescence can be induced by 10 μM Cu2+, 30 μM Ni2+ cations, 500 nM T3, and 800 nM T4 hormones. Fluorescence quenching efficiencies were calculated for Cu2+, Ni2+, T3, and T4 99.7%, 99.6%, 98.7%, and 98.2%, respectively.

Ultrasensitive and highly selective detection of nickel ion by two novel optical sensors

Novel optical sensors for nickel determination by incorporation of 5-(2`-bromo-phenylazo)-6-hydroxypyrimidine-2,4-dione (I), 5-(2`,4`-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (II), dibutylphthalate (DBP) and sodium tetra-phenylborate (Na-TPB) to the plasticized polyvinyl chloride matrices were prepared. The introduction of DBP in the membrane substantially increased the ability of both ionophores I and II to function as chromo ionophores. The advantages of the reported sensors include great stability, reproducibility, and relatively long lifespan, as well as excellent selectivity for Ni2+ ion detection across a wide range of alkali, alkaline earth, transition, and heavy metal ions.Under optimized membrane compositions and experimental parameters, the response of both sensors was linear throughout a concentration range of 3.5 × 10-8 to 8.1 × 10-5 and 2.0 × 10-8 to 5.1 × 10-5 M for I and II, respectively. Sensor detection and quantification limits based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three and ten times its standard deviation were determined to be 1.15 × 10-8 and 3.45 × 10-8 M when utilizing I, whereas they were 0.61 × 10-8 and 1.95 × 10-8 M when utilizing II, respectively. The reaction time of optodes is defined as the period required achieving 95% of based sensors and found to be 8.0 and 5.0 min using I and II, respectively. Ni2+ ion concentrations in water, food, and environmental samples were effectively determined using the proposed optical sensors. Representative diagram for preparation of the sensing Ni2+ sensor.