Micro-spectrophotometric determination of nickel in Gentiana rigescens after switchable hydrophilicity solvent-based ultrasound-assisted liquid phase microextraction

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.

Ultrasound-assisted switchable hydrophilic solvent-based homogeneous liquid-liquid microextraction for the determination of triazole fungicides in environmental water by GC-MS

A new method was developed for the determination of three triazole fungicides in environmental water samples by gas chromatography-mass spectrometry (GC-MS) based on ultrasonic assisted switchable hydrophilic solvent homogeneous liquid-liquid microextraction. As a switchable hydrophilic solvent, N,N-dimethylcyclohexylamine (DMCHA) does not require a dispersant or centrifugation. Ultrasound assistance is helpful to speed up the extraction of target compounds and can reduce the pretreatment time. The entire pretreatment process of this method only takes 5 minutes. Using the Box-Behnken design as the means of optimization, optimal extraction conditions were obtained through a mathematical model. Good linearity was obtained in the range of 5-500 μg L^-1, and the correlation coefficient of target compounds was greater than 0.999. The matrix spiked recoveries were between 81.3% and 111.1% and the detection limit was between 0.46 and 0.99 μg L^-1. Intraday relative standard deviation (n = 3) was 13.0-13.9% at 100 μg L^-1. Finally, it was concluded that the method is a rapid, efficient and simple method for the analysis of triazole fungicides in water.

Fast sequential multi element analysis of lead and cadmium in canned food samples using effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) coupled with high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS)

An effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) was developed for multi-element determination of Pb and Cd in various samples using high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS). The effervescent tablets were used for improving the extraction efficiency. Triethylamine as a hydrophobic solvent was switched to protonated triethylamine carbonate by CO₂ and used to extract dithizone complexes from samples. Calibration linearities were obtained from 0.06 to 10.0 mg L^-1 (Pb) and 0.02 to 1.50 mg L^-1 (Cd). LODs of the proposed method were 0.0195 (Pb) and 0.0068 (Cd). LOQs were 0.0649 mg L^-1 (Pb) and 0.0228 mg L^-1 (Cd) with %RSDs of 1.25%-1.69% (Pb) and 1.07%-1.64% (Cd). The proposed method was applied for the determination of Pb and Cd in water and canned food samples. The spiked recoveries were 82.3-119.0% (Pb) and 81.7-120.0% (Cd). In addition, the PF was 3.3, with EF at 1.4 (Pb) and 2.6 (Cd) obtained after extraction for under 8 min.