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In this work, walnut green husk has been used as a simple, cheap, biodegradable, and efficient adsorbent in dispersive solid phase extraction of Cd(II) and Pb(II) ions from some oil samples including edible, fish oil, and butter. In the next step, a dispersive liquid-liquid microextraction method was used to enrich the extracted analytes before their analysis with flame atomic absorption spectrometry. For this purpose, the adsorbent was obtained from agricultural wastes, dried in an isolated environment at ambient temperature, and mechanically ground to obtain a homogeneous powder. The parameters affecting the efficiency of the method were optimized. Low detection limits (0.12 and 0.32 µg l-1 for Cd(II) and Pb(II), respectively), low relative standard deviations (3.8% and 4.2% for Cd(II) and Pb(II), respectively), and determination coefficients close to 1 (0.991 and 0.995 for Cd(II) and Pb(II), respectively) were achieved. Also, the extraction recoveries for the target analytes were 89 and 96% for Cd(II) and Pb(II), respectively. [ABSTRACT FROM AUTHOR]

In present study, efficiency of three rapid, simple, and reliable sample preparation methods namely dispersive liquid–liquid microextraction (DLLME), air-assisted liquid–liquid microextraction (AALLME), and CO2-assisted liquid–liquid microextraction (CO2-ALLME) have been compared for the extraction and preconcentration of Pt(IV) and Pd(II) ions in environmental water samples prior to flame atomic absorption spectrometry. In this regard, the effect of various experimental parameters on efficiency of the methods like nature and amount of the disperser and extraction solvents, ionic strength, temperature, pH, etc., are investigated to reach high enrichment factors. Due to organic solvent consumption at µL level, all of the studied methods are inexpensive and convenient. The linear ranges of the calibration curves were 10.0–200, 6.0–175, and 6.0–175 μg L−1 for Pd(II), and 20–200, 4.0–200, and 7.0–200 μg L−1 for Pt (IV) ions in DLLME, AALLME, and CO2-ALLME methods, respectively. Extraction recoveries of 81.4, 92.1, and 88.9% for Pd (II) and 85.3, 98.4, and 93.4% for Pt(IV) ions were obtained in DLLME, AALLME, and CO2-ALLME, respectively. Finally, the developed methods were successfully used for the analysis of Pt(IV) and Pd(II) in various water samples. [ABSTRACT FROM AUTHOR]

A green effervescence-assisted dispersive liquid-liquid microextraction based on phthalic acid as complexing agent and co-disperser performed in a narrow-bore tube has been developed for the extraction and preconcentration of zinc and cadmium from high volume of aqueous sample, followed by flame atomic absorption spectrometry. Initially phthalic acid is added to the aqueous sample to form phthalate-metal complexes. Then the sample is transferred by a syringe into a home-made setup consists of a narrow-bore glass tube with its nozzle-shaped head when its bottom connected to a glass balloon containing sodium bicarbonate and an extraction solvent at μL-level. Immediately a reaction occurs between the sodium bicarbonate and the excess amount of phthalic acid, and the produced CO 2 leads to the dispersion of the extractant into the sample as fine droplets which result in extraction of the complexes into the extractant. Under the optimum conditions, the calibration curves were linear in the ranges of 0.50–7.5 and 0.30–7.5 μg L−1 for cadmium and zinc, respectively. The detection limits were 0.21 and 0.14 μg L−1 for cadmium and zinc, respectively. Extraction recoveries were 89% and 100%, and enrichment factors were found to be 117 and 131, for cadmium and zinc, respectively. Finally environmental water and fruit juice samples were successfully analyzed using the developed method. • A green effervescence-assisted DLLME based on phthalic acid performed in a narrow-bore tube has been developed. • For the first time, phthalic acid was simultaneously used for complexing of analytes and as co-disperser in DLLME. • DLLME was performed without addition of toxic complexing agent and disperser solvent. • Much low of an organic solvent was used as the extraction solvent in the absence of disperser solvent, for high volume (25 mL) of sample. • The linearity, ER, EF, and repeatability of the method were validated within the acceptable ranges. [ABSTRACT FROM AUTHOR]

A green, simple, rapid and efficient solventless temperature-assisted homogeneous liquid-liquid microextraction based on 8-hydroxyquinoline as complexing agent and extractant, followed by flame atomic absorption spectrometry was developed for the extraction, enrichment, and determination of trace amounts of nickel and cobalt in aqueous samples. For this purpose, first, a specified amount of 8-hydroxyquinoline is added to the analytes solution. Then the temperature of the solution is increased to melt 8-hydroxyquinoline and form a homogeneous solution. Then, it is cooled to room temperature and a cloudy solution is formed due to decreasing 8-hydroxyquinoline solubility. The solution is then centrifuged, and 8-hydroxyquinoline particles containing the produced complexes (8-hydroxyquinoline-cation) are collected at the bottom of the tube. They are removed and dissolved in a suitable solvent and injected to the detection system. The main parameters affecting the extraction efficiency, such as the amount of 8-hydroxyquinoline, solvent nature, pH, extraction temperature and heating time were investigated. Under optimum conditions, linear ranges for Co(II) and Ni(II) were 1-100 and 0.5-75 µg L−1, respectively. Relative standard deviations for intra- and inter-day precisions calculated from six repeated determinations at three different concentrations of Co(II) and Ni(II) were ≤5.2 %. Moreover, the obtained detection limits of the analytes were 0.35 and 0.20 µg L−1 for Co(II) and Ni(II), respectively. The accuracy of the developed procedure was checked by analysing SPS-WW2 Batch 108 water as a certified reference material. Finally, the developed method was successfully applied for the determination of the selected cations in water and fruit juice samples. [ABSTRACT FROM AUTHOR]

In this work, an efficient magnetic sorbent has been prepared using the extract of Tanacetum leaves and used in magnetic dispersive solid phase extraction of Cu(II) and Pb(II) ions from high volume of milk samples performed in a narrow-bore tube. For this purpose, first, the sorbent was prepared by mixing Fe 3 O 4 magnetic nanoparticles and Tanacetum leaves extract. After precipitation of the milk proteins with trichloroacetic acid, the sedimented compounds were removed and the upper solution was filled into the narrow-bore tube. Then after that, the mg-level of the prepared sorbent was added. After doing the extraction procedure, the sorbent particles were removed from the tube in the presence of a magnetic field. The adsorbed analytes were desorbed by methanol and to achieve low detection limits, the eluent obtained from the first step was subjected to dispersive liquid-liquid microextraction. Finally, the enriched analytes were monitored by flame atomic absorption spectrometry. The important parameters affecting the method efficiency such as the sorbent amount, type and volume of elution and extraction solvents, vortex time, pH, and ionic strength were studied. Under optimized conditions, the proposed method showed linear ranges of 0.50–40 and 0.75–40 µg L−1 for Cu(II) and Pb(II) ions, respectively. Limits of detection were obtained 0.16 and 0.22 µg L−1 for Cu(II) and Pb(II), respectively. Enrichment factors of 182.5 and 173.7 and extraction recoveries of 95.8 % and 91.2 % were obtained for Cu(II) and Pb(II), respectively. The relative standard deviations (intra- and inter-day precisions) for 5 and 25 µg L−1 of each cation were between 2.4 % and 4.3 %. • Tanacetum extract was used for functionalisation of Fe 3 O 4. • The prepared MNPs was used for the extraction of heavy metals from milk. • The MDSPE was combined with a dispersive liquid-liquid microextraction procedure. • The method has low LODs and LOQs, high EFs and ERs. [ABSTRACT FROM AUTHOR]