Selective dispersive micro solid-phase extraction using oxidized multiwalled carbon nanotubes modified with 1,10-phenanthroline for preconcentration of lead ions

Novel Graphene oxide-Polyethylene Glycol mono-4-nonylphenyl Ether adsorbent for solid phase extraction of Pb2+ in blood and water samples

A novel and efficient Graphene Oxide-Polyethylene Glycol mono-4-nonylphenyl Ether (GO-PEGPE) nanocomposite was synthesized and used for solid phase extraction of trace levels of Pb²⁺ in different water and blood samples. The synthesized adsorbent was then characterized by the Fourier Transform-Infrared spectrophotometry (FT-IR), Field Emission-Scanning Electron Microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction analysis (XRD). To optimize the critical parameters including pH of samples solution, amounts of adsorbent and extraction time, the response surface methodology based on the central composite design (RSM-CCD) was used and based on the results, pH = 6.0, extraction time = 22 min and amounts of adsorbent = 15 mg were selected as the optimum conditions. The relative standard deviation based on seven replicate analysis of 2 µg L^-1 Pb²⁺ was 5.2% and the limit of detection was 0.023 µg L^-1 (n = 8). The results of adsorption isotherm investigation show that the adsorption of Pb²⁺ onto the GO-PEGPE nanocomposite obeyed by the Langmuir isotherm with the maximum adsorption capacity of 69.44 mg g^-1. Also, based on the Temkin and Dubinin-Radushkevich (DR) isotherms, the adsorption of Pb²⁺ onto the GO-PEGPE nanocomposite is a physisorption phenomenon and the consequences of the kinetic models illustrated that the adsorption of Pb²⁺ followed by the pseudo second order adsorption kinetic model. Finally, the proposed method was successfully applied for preconcentration of Pb²⁺ in different water and blood samples of turning industry workers.

Vortex-assisted restricted access-based supramolecular solvent microextraction of trace Pb(II) ions with 4-(benzimidazolisonitrosoacetyl)biphenyl as a complexing agent before microsampling flame AAS analysis

A new oxime compound, 4-(benzimidazolisonitrosoacetyl)biphenyl (BIBP) was synthesized and used as a complexing agent in this study to preconcentrate trace amounts of Pb(II) ions with vortex-assisted restricted access-based supramolecular solvent microextraction (RA/SUPRAS-LPME) method. The new complexing agent was characterized by a combination of elemental analyses, Proton Nuclear Magnetic Resonance (¹H- NMR), Carbon-13 Nuclear Magnetic Resonance (¹³C NMR) and Fourier Transform Infrared spectroscopy (FT-IR) and techniques. Extraction of the complex which was formed at pH 8.0 was done by using a supramolecular solvent phase of tetrahydrofuran (THF) and 1-decanol. A microsampling flame atomic absorption spectrophotometer was used to measure the lead ion concentrations of the extract. The method optimized and the optimum experimental conditions were found as; pH = 8, amount of the ligand 2,25 mg, supramolecular solvent volume 50 μL, sample volume 20 mL and vortex time 3 min. The limit of detection (LOD), limit of quantification (LOQ) were calculated as 0.69 μg L^-1 and 2.29 μg L^-1, respectively. Linear range was found between 15.1 μg L^-1 and 606 μg L^-1. The developed method was applied to Pb(II) determination in real samples after evaluating the accuracy by using the TMDA-53.3 fortified environmental water sample as certified reference material.

Effect of operating variables on the separation of radiostrontium from aqueous matrices with ion-selective solid-phase extraction systems

Radiostrontium (r-Sr: ⁹⁰Sr) is one of the primary fission products in nuclear power plants and generates liquid radioactive waste when intermixed to the aqueous matrix. Therefore, separation or preconcentration of r-Sr from the aqueous matrices is necessary for environmental monitoring or nuclear forensics. The solid-phase extraction (SPE) approach is prevalently used for r-Sr isolation and to design matrix-specific methods, while generalized SPE-assisted operating protocols are not proposed by far. In the current work, four different SPEs, namely AnaLig Sr-01, Eichrom Sr, Triskem TK100, and Eichrom DGA, were evaluated for selective separation of Sr from aqueous matrices. Operating variables, e.g., solution acidity, washing solvent, eluent-type or volume, loading or elution flow-rate, were varied to optimize the SPEs performance. The objective was to ascertain the operating variables for maximum Sr-separation yield from aqueous environmental samples with the SPEs mentioned above. In addition, the Sr-separation efficiency of SPEs was evaluated by calculating the separation factor (SF_Sr/M) between Sr and interfering elements to r-Sr (M = Ca, Mg, Ba, or Y), and the Sr-retention capacity of the SPEs was determined. Finally, the optimized operating variables for the evaluated SPEs were used to construct protocols for r-Sr separation from aqueous matrices. Real ⁹⁰Sr contaminated aqueous samples from the Chernobyl nuclear power plant cooling pond were treated by those protocols, and the results are validated comparing with the IAEA-recommended classical protocol. All the SPEs were able to isolate Sr at varying extents from matrices at the optimum conditions, even at much higher contents of interfering elements. Eichrom Sr or AnaLig Sr-01 showed better Sr-retention capability among the SPEs, while Triskem TK100 showed superiority over other SPEs regarding Sr-selectivity.

Magnetic nanobiosorbent (MG-Chi/Fe3 O4 ) for dispersive solid-phase extraction of Cu(II), Pb(II), and Cd(II) followed by flame atomic absorption spectrometry determination

Trace amounts of Cu (II), Pb (II), and Cd (II) in a wastewater sample were preconcentrated with a novel cross‐linked magnetic chitosan modified with a new synthesised methionine‐glutaraldehyde Schiff's base (MG‐Chi/Fe₃O₄) as a dispersive solid‐phase extraction (DSPE) adsorbent. The adsorbed metal ions were then eluted with a specific volume of suitable solution and determined by flame atomic absorption spectrometry (FAAS). Various parameters affecting the extraction efficiency of the metal ions were investigated and optimised, including pH, amount of adsorbent, extraction time, type and volume rate of eluent, elution time, sample volume, and effect of interfering ions. The adsorption kinetics are more consistent with the pseudo‐second order model. The results were statistically interpreted and the analytical performance of the proposed method was found to have preconcentration factors of 55, 60, and 50 μg L⁻¹ for Cu(II), Pb(II), and Cd(II), respectively, limits of detection were 0.22, 0.24, and 0.10 μg L⁻¹ for Cu(II), Pb(II), and Cd(II), respectively, with a relative standard deviation (1.5%‐2.8 %), and the liner range was 5–1000 for Cu(II) and Pb(II) and 2.5–1000 for Cd(II). It was concluded that this method was suitable for successful simultaneous determination of Cu(II), Pb(II), and Cd(II) in industrial wastewater samples.

A novel vortex assisted dispersive solid phase extraction of some trace elements in essential oils and fish oil

In this paper, a novel vortex assisted solid phase extraction procedure combined with inductively coupled plasma optic emission spectrometry was presented for determination of Mn, Cu, Ni, Cr, Cd and Pb directly in oily matrix. The suggested separation and preconcentration method was based on simultaneous sorption of the target analytes from real essential oil matrix onto γ-Al₂O₃ functionalized with fluorescein (Al-Flr) and transfer to aqueous eluent prior to quantification. The effect of different parameters including sorption and elution time, sample volume, eluent type and concentration and interfering ions were investigated. The working conditions were given as follows, vortex agitation for sorption and elution 40 s, sample volume 20 mL, eluent type HCl, eluent concentration 0.3 mol L^-1. The detection limits were found to be 0.7 μg L^-1 for Mn, 4.1 μg L^-1 for Cu, 1.0 μg L^-1 for Ni, 1.6 μg L^-1 for Cr, 0.7 μg L^-1 Cd and 1.0 μg L^-1 Pb. The evaluation of the accuracy and precision of the method was tested via metallo-organic certified reference material. The recovery values have warranted the accuracy and found between 98.4 and 103.3% with 2.6-6.4% relative standard deviation (RSD, %). The sampling frequency of the procedure was calculated as 11.25 h^-1. Finally, the proposed analytical method was successfully applied on analyte spiked and unspiked apricot, black cumin, pine turpentine, thyme, mint essential oils and fish oil samples without any need of performing mineralization pretreatments.

Determination of toxic heavy metals in fish samples using dispersive micro solid phase extraction combined with inductively coupled plasma optical emission spectroscopy

Monitoring of toxic heavy metals in fish samples is a matter of a great importance from the nutritional and toxicological points of view. A dispersive micro solid phase extraction (dµSPE) for preconcentration of trace Pb, Cd, Hg, Co, Ni ions using pectin coated magnetic graphene oxide (pectin/Fe₃O₄/GO) is presented. Inductively coupled plasma optical emission spectroscopy (ICP/OES) was utilized for analyzing the samples. The influence of parameters name as pH, extraction time, sample volume and amount of sorbent were optimized using central composite design (CCD) methodology. Detection and quantification limits were between 0.01 and 0.21 µg g^-1 and 0.04-0.67 µg g^-1 of fresh fish sample, respectively. Accuracy of the method verified using certified reference materials (NIST-SRM-1946). Concentration of the toxic heavy metals were successfully determined in 11 different fish samples using the proposed method.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Green Dispersive Micro Solid-Phase Extraction using Multiwalled Carbon Nanotubes for Preconcentration and Determination of Cadmium and Lead in Food, Water, and Tobacco Samples

Background:

Cadmium (Cd2+) and lead (Pb2+) have acute and chronic effects on humans and other living organisms. In the present work, new, green and accurate dispersive micro solid-phase extraction (DμSPE) method for the separation and preconcentration of trace amounts of cadmium (Cd2+) and lead (Pb2+) ions in various food, water and tobacco samples collected from Saudi Arabia prior to its Flame Atomic Absorption Spectrometric (FAAS) determinations was developed.

Methods:

The proposed method was based on a combination of oxidized multiwalled carbon nanotubes (O-MWCNTs) with a new chelating agent 5-benzyl-4-[4-methoxybenzylideneamino)-4H- 1,2,4-triazole-3-thiol (BMBATT) to enrich and separate trace levels of Cd2+ and Pb2+. The effect of separation parameters was investigated. The validation of the proposed preconcentration procedure was performed using certified reference materials.

Results:

Analyte recovery values ranged from 95-102%, indicating that the method is highly accurate. Furthermore, precision was demonstrated by the relative standard deviation (RSD < 3.0%). The limits of detection were 0.08 and 0.1 μg L−1 for Cd2+ and Pb2+ ions, respectively. The preconcentration factor was 200.

Conclusion:

The proposed method was used for the estimation of Cd2+ and Pb2+ ion content in various real samples, and satisfactory results were obtained. The proposed method has high adsorption capacity, rapid adsorption equilibrium, extremely low LODs, high preconcentration factors and shortens the time of sample preparation in comparison to classical SPE.

Preconcentration of Lead in Blood and Urine Samples Among Bladder Cancer Patients Using Mesoporous Strontium Titanate Nanoparticles

In this work, mesoporous strontium titanate nanoparticles (SrTiO₃ NPs) were synthesized through a single-step combustion process and were characterized by FT-IR, XRD, SEM-EDX, and TEM. The effects of main parameters that may influence the extraction process (i.e., pH, sorbent amount, time of extraction, eluting agent, and the presence concomitant ions) were investigated. The optimum extraction was achieved at pH 6, 50 mg of sorbent, 20-min shaking time, and 4.0 mL of 0.1 mol L^-1 thiourea as desorption agent. Under these conditions, the maximum adsorption capacity was 155.6 mg g^-1 with a preconcentration factor of 250 (for a 1000 mL sample solution). The calibration graph was linear up to 1000 μg L^-1 and the limit of detection was 1.75 μg L^-1. The precision (as relative standard deviation) was 2.53% (n = 10). The procedure was employed for the preconcentration of Pb²⁺ from blood and urine samples of bladder cancer patients before its determination by FAAS.

Graphene oxide chemically modified with 5-amino-1,10-phenanthroline as sorbent for separation and preconcentration of trace amount of lead(II)

Graphene oxide (GO) was chemically functionalized with 5-amino-1,10-phenanthroline. The resulting conjugate (phen-GO) was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The experiments show that phen-GO has a high affinity for extraction of Pb(II) ions. Isotherms and kinetics fit the Langmuir model and pseudo-second-order equations. By using phen-GO as a sorbent, Pb(II) ions can be quantitatively adsorbed at pH 6.0. The adsorption capacity is 548 mg g^-1. Following desorption with 2 mol L^-1 HNO₃, Pb(II) was quantified by inductively coupled plasma optical emission spectrometry. The effects of pH value, eluent type, sorption time, sample volume, and matrix ions were optimized. The accuracy of the method was validated by analysis of the reference materials DOLT-3 (dogfish liver) and SRM 1640a (natural water). Under optimal conditions, the calibration plots cover the 0.25 to 500 ng mL^-1 Pb(II) concentration range. The method was successfully applied to the analysis of spiked water and biological samples. Other figures of merit include a preconcentration factor of 250, a detection limit of 46 ng L^-1, and a relative standard deviation of <5%. Graphical abstract Schematic presentation of the dispersive solid-phase extraction of lead(II) ions using graphene oxide modified with 5-amino-1,10-phenanthroline, followed by their determination by inductively coupled plasma optical emission spectrometry (ICP OES).

Micro-solid phase extraction of some polycyclic aromatic hydrocarbons from environmental water samples using magnetic β-cyclodextrin-carbon nano-tube composite as a sorbent

Previous studies have demonstrated the excellent capability of the cyclodextrins in pre-concentration of the organic pollutants from the aqueous solutions. In this work, β-cyclodextrin- multiwalled carbon nano-tube composite was produced from the reaction of oxidized carbon nano-tube with cyclodextrin in the presence of the hydrazine hydrate, and subsequently attaching this composite to the iron oxide nano-particles. Prepared magnetic nano-composite was characterized by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), the thermogravimetric analysis (TGA), the field emission scanning electron microscopy (FESEM), and the X-ray diffraction (XRD). This composite was applied to extract seven polycyclic aromatic hydrocarbons (PAHs) from the environmental water samples as follows: naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene and benzo[a]pyrene. Analytes analysis was performed using the gas chromatography (GC) followed by the flame ionization detection (FID), and the predominant parameters influencing the extraction efficiency were investigated thoroughly. Under the optimized extraction conditions, the enrichment factor (EF) was ranging from 41.3 to 49.3 (EF_max = 50.0), and a suitable linearity was obtained (R² = 0.992-0.997) within the range of 2.0-1000 ng/mL. The limits of the quantification and detection were 2.0-10.0 and 0.6-3.0 ng/mL, respectively. Finally, the synthesized magnetic sorbent and method were successfully utilized for the analysis of rain, well and agricultural water samples. The relative recoveries were ranging from 75.3-107.0% with an acceptable precision (5.5-8.3%) for PAHs extraction.