Preconcentration Of Lead Research Articles

A simple and green deep eutectic solvent based air assisted liquid phase microextraction for separation, preconcentration and determination of lead in water and food samples by graphite furnace atomic absorption spectrometry

In this study, an air assisted liquid phase microextraction based on deep eutectic solvent (AA-DES-LPME) method was developed for separation, preconcentration and determination of lead followed by graphite furnace atomic absorption spectrometry (GFAAS). The complexation of Pb(II) was carried out by using 4-(2-thiazolylazo) resorcinol as complexing agent at pH6. Deep eutectic solvent was prepared by using choline chloride phenol (ChCl-Ph) and was added to an aqueous solution containing analyte, and then mixture was sucked up and injected nine times with the help of a syringe, and a cloudy state was attained. After extraction, the solution was centrifuged and upper layer was separated and Pb(II) ions was determined by GFAAS. Different parameters were investigated and optimized including pH, volume and type of DES, effect of ligand volume, effect of pulling and pushing cycles. Under optimum conditions, the detection limit, limit of quantitation were observed as 0.60ngL−1 and 1.98ngL−1, respectively. Preconcentration factor (PF) and relative standard deviation (RSD) were found to be 60 and 2.9%, respectively. Certified reference materials (CRMs) were used to check the accuracy of developed technique. Finally, present procedure was fruitfully used for analysis of Pb(II) in various food and water samples.

Nafion coated flexible bismuth sensor for trace lead and cadmium determination

This paper reports a low-cost and highly sensitive flexible sensor for the determination of lead and cadmium in tap and lake water. This sensor achieved low detection limits and high performance by decorating cation-exchanging resin and in situ deposited bismuth on the working electrode. In situ deposited bismuth film was much easier to fabricate and formed a highly porous 3-dimensional structure, which provided more surface area for the reaction of the target ions. The cation-exchanging Nafion film can help reduce the interference caused by surface active compounds and enhance the pre-concentration of lead and cadmium at the same time. Flexible polypropylene film was chosen as the substrate to reduce the cost and expand the sensor's applications. Finally, the detection limits were 1.68 ppb for Pb and 1.24 ppb for Cd at the deposition time of 300 s. Particularly, this sensor revealed good linearity (R2ý=ý0.993) at a wide range of 10---500 ppb for cadmium in tap water environment. The proposed sensor was successfully applied to lead and cadmium determination in environmental water samples and the results were in good agreement with those from a standard procedure.

Ultrasound-assisted surfactant-enhanced emulsification microextraction using a magnetic ionic liquid coupled with micro-solid phase extraction for the determination of cadmium and lead in edible vegetable oils

A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) using a magnetic ionic liquid (MIL) coupled with micro-solid phase extraction was developed for the preconcentration of cadmium and lead in edible vegetable oils prior to analysis by graphite furnace atomic absorption spectrometry. MIL [C4mim] [FeCl4] was used as the extractant, non-ionic surfactant Triton X-100 as the emulsifier and Fe3O4 nanoparticles as the sorbent, while ultrasound was applied to assist the dispersion of the extractant and accelerate the mass transfer process. By mixing Fe3O4 nanoparticles with the MIL after UASEME, the phase separation time was shortened and the separation can be simplified by applying an external magnetic field. Under the optimized conditions, the proposed method was validated and the results demonstrated that the method can produce satisfactory linearity, sensitivity, reproducibility and recovery for the analytes. Finally, the method was successfully applied for the determination of Cd and Pb in edible vegetable oil samples.

Dispersive liquid–liquid microextraction using the freezed floating organic drop for rapid, fast, and sensitive determination of lead

ABSTRACTA rapid, simple, and sensitive method was developed for lead preconcentration and separation in various real samples by dispersive liquid–liquid microextraction based on the freezing of floating organic drop. In this method, a suitable extraction solvent dissolved in a dispersive solvent was quickly syringed into the water sample so that the solution became turbid. Then, two phases were separated by centrifugation. The floating extractant droplet can be easily solidified on an ice bath and taken out of the water sample. Then, it can be liquefied instantly at room temperature, and analyte can be determined in it. In the creation of a hydrophobic complex with lead, 1-(2-pyridylazo)-2-naphthole (PAN) was used as the chelating agent. 1-Undecanol and acetone were used as extraction and disperser solvent. To achieve the highest recovery, some factors (type and volume of dispersive and extraction solvent, pH, PAN concentration, and salt concentration) were optimised. Under optimised conditions (pH = 9, 1.0 × 10–3 mol L−1 PAN, 15% w/v NaCl, 100 µL 1-undecanol, and 0.3 mL acetone), the lead calibration graph was linear from 1.5 to 80 μg L−1. The detection limit and preconcentration factor were 0.5 μg L−1 and 50, respectively. Lead was successfully determined in water and food (spinach, rice, potato, carrot, and black tea bag) samples by this method.

Extraction and pre-concentration of lead from copper by emulsion liquid membrane technique using an ionic liquid

The study of the recovery process of lead from aqueous nitrate medium using emulsion liquid membrane technique was achieved by the optimization of the extraction and pre-concentration of Pb(II) ions. This has been conducted by the method of optimizing one experimental parameter at a time. The chemical process of recovery consists of a quaternary amine salt (Aliquat 336) as ionic liquid extractant and a non-ionic surfactant (Tween20) as reagent for dispersion and emulsion formation. Thus, several experimental parameters such as carrier concentration, surfactant concentration, time and stirring speed of feed phase, initial concentration and pH of feed concentration phase were studied. Pb(II) ions extraction was optimized using tri-n-octylphosphine oxide (TOPO) as the solvating organophosphorus compound in the emulsion phase. From the results, the lead ions were extracted at 92 ± 0.04% by Aliquat 336 in the presence of TOPO. For the stage of Pb(II) pre-concentration, the nature and concentration effects of the stripping solution were studied. So, the loss of the Pb(II) ions in the membrane phase was minimal when using the nitric acid solution as a stripping solution. It was preconcentrated at 83.55%. The separation experiments of Pb(II) from Cu(II) were given on the basis of the optimal conditions of lead(II) recovery. Thus, the separation factor of lead over copper was equal to 1.47.

Activated carbon cloth filled pipette tip for solid phase extraction of nickel(II), lead(II), cadmium(II), copper(II) and cobalt(II) as 1,3,4-thiadiazole-2,5-dithiol chelates for ultra-trace detection by FAAS

ABSTRACTA solid phase extraction method is established for preconcentration of nickel, lead, cadmium, copper and cobalt using pipette tip solid phase extraction. The presented process was dependent on chelation of analytes with 1,3,4-thiadiazole-2,5-dithiol, then allowing the solution to flow through an activated carbon cloth packed pipette tip. The adsorbed metal chelates on the surface of activated carbon cloth were eluted by 5 mL of 3 M HNO3. The concentrations of nickel, lead, cadmium, copper and cobalt were detected using a flame atomic absorption spectrometer (FAAS). The pipette tip solid phase extraction exhibit a preconcentration factor of 120. The limit of detection values were 2.7, 1.7, 1.3, 2.0 and 2.9 µg L−1 for Ni(II), Pb(II), Cd(II), Cu(II) and Co(II), respectively. Validation of the method was checked by the analysis of TMDA-53.3 and TMDA-64.2 certified reference materials. The method was successfully applied for water and fertiliser samples.

Simultaneous Determination of Bismuth, Lead, and Iron in Water Samples by Optimization of USAEME and ICP–OES via Experimental Design

Ultrasound-assisted emulsification–microextraction followed by inductively coupled plasma–optical emission spectrometry was utilized for simultaneous pre-concentration and trace detection of lead, bismuth, and iron in water samples. Disodium N,N $$^\prime$$ -bis(salicylidene)ethylenediamine and trichloroethylene were used as chelating agent and extraction solvent, respectively. The parameters of interest were volume of extraction solvent, temperature, and concentrations of salt and chelating agent. A fractional factorial design was developed to identify these parameters and how they vary with one another. The results demonstrated that the concentrations of salt and chelating agent affected extraction efficiency. Subsequently, a central-composite design was used to acquire optimum levels of effective parameters. The optimal conditions were 160.7 mg L $$^{-1}$$ and 1.77% (w/v) for concentration of chelating agent and salt, respectively. The linear dynamic ranges were determined to be 1–1000 $$\upmu$$ g L $$^{-1}$$ for Pb and Bi, and 10–1000 $$\upmu$$ g L $$^{-1}$$ for Fe. The correlation coefficient ( $$R^2$$ ) was 0.990–0.995. The limits of detection were 0.54–0.78 $$\upmu$$ g L $$^{-1}$$ . The relative standard deviation (concentration $$=$$ 200 $$\upmu$$ g L $$^{-1}$$ , $$n = 8$$ ) was in the range of 2.0–4.3%. This method was successfully applied for the trace detection of Pb, Bi, and Fe in freshwater samples of waterfall and spring and satisfactory relative recoveries (96.2–99.6%) were obtained.

Development of cloud point extraction preconcentration of cadmium and lead in solid samples using flame atomic absorption spectrometry

Development of cloud point extraction preconcentration of cadmium and lead in solid samples using flame atomic absorption spectrometry

Adsorption–photometric determination of lead in cattle liver

A styrene–maleic anhydride copolymer is synthesized, modified in the presence of p-sulfoaniline and formaldehyde, and a new polymer adsorbent is obtained and identified by IR spectroscopy. The ionization constants of ionogenic groups in the adsorbent are determined by the potentiometric method. The adsorption and desorption of lead(II) on the obtained adsorbent are investigated, and optimal conditions of preconcentration are determined. An adsorption–photometric procedure for the determination of lead is proposed, including the adsorption preconcentration of lead(II) from a buffer solution with pH 6 and desorption with a solution of HCl (with the desorption rate of up to 99%). The procedure was used to determine lead in the cattle liver.

Application of Chitosan-Zinc Oxide Nanoparticles for Lead Extraction From Water Samples by Combining Ant Colony Optimization with Artificial Neural Network

Сhitosan-zinc oxide nanoparticles (CZPs) were developed for solid-phase extraction. Combined artificial neural network–ant colony optimization (ANN–ACO) was used for the simultaneous preconcentration and determination of lead (Pb2+) ions in water samples prior to graphite furnace atomic absorption spectrometry (GF AAS). The solution pH, mass of adsorbent CZPs, amount of 1-(2-pyridylazo)-2-naphthol (PAN), which was used as a complexing agent, eluent volume, eluent concentration, and flow rates of sample and eluent were used as input parameters of the ANN model, and the percentage of extracted Pb2+ ions was used as the output variable of the model. A multilayer perception network with a back-propagation learning algorithm was used to fit the experimental data. The optimum conditions were obtained based on the ACO. Under the optimized conditions, the limit of detection for Pb2+ ions was found to be 0.078 μg/L. This procedure was also successfully used to determine the amounts of Pb2+ ions in various natural water samples.

A New Dispersive Liquid-Liquid Microextraction Method for Preconcentration and Determination of Aluminum, Iron, Copper, and Lead in Real Water Samples by HPLC.

In this study, dispersive liquid-liquid microextraction coupled with HPLC with variable-wavelength detection was applied for the simultaneous determination of Al, Fe, Cu, and Pb in various water samples at trace levels. In the proposed method, all the system parameters in both the extraction and separation/determination steps, such as extraction and disperser solvent type and their volumes, complexing reagent concentration, salt addition, extraction and centrifugation times, and pH, were optimized to get not only high extraction efficiency but also lower LODs for the analytes. Hematoxylin was used as a complexing reagent, and carbon tetrachloride and methanol were chosen as the extraction and disperser solvents, respectively. Metal complexes were separated with a reversed-phase C18 column by isocratic elution, with methanol-tetrahydrofuran-water (20 + 12 + 68, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min and detection at 575 nm. The accuracy of the method was checked by a Standard Reference Material of water (SRM 1643e), and the recovery values for the analytes were found in the range of 95.6-101.3%. Under the optimum conditions, the developed method was applied to tap water, bottled mineral water, lake water, and seawater for the accurate and sensitive determination of the analytes of interest.

Magnetic Graphene Oxide as an Efficient Adsorbent for the Separation and Preconcentration of Cu(II), Pb(II), and Cd(II) from Environmental Samples

The separation and preconcentration of copper(II), lead(II), and cadmium(II) ions on magnetic graphene oxide (MGO) by solid-phase extraction was carried out. Quantitative recovery was obtained by adsorption of analytes on MGO at pH 6 and elution of 3 M HNO3 in 10% acetone. To optimize the presented method, the effects of various parameters-including pH, eluent conditions, and vortex time-were examined. Matrix effects were also investigated. Mean recoveries of the analytes were between 95 and 105%. The proposed method was validated by applying it to certified reference materials. Addition and recovery tests were also performed. The method was applied to verify the analyte content of several water and food samples.

Preconcentration and Determination of Lead for Trace Levels in Water and Wastewater Samples by Vortex-Assisted Microextraction Using TPAS as a New Synthetic Complexing Agent with Electrothermal Atomic Absorption Spectroscopy Detection

A simple and rapid solidified vortex assisted 1-undecanol based liquid-liquid microextraction technique was proposed for preconcentration of trace levels of lead ions. The extraction solvent (1-undecanol) was dispersed into the aqueous samples by the assistance of vortex agitator. 100 µL of 1-undecanol containing ethyl (2Z)-3-[(5-chloro-7-methyl[1,3]thiazolo[5,4-d]pyrimidin-2-yl)amino]-2-cyano-3-(methylsulfanyl)prop-2-enoate (TPAS) as a new chelating agent (0.1%w/v) was transferred to the water samples containing lead ions. The hydrophobic complex was extracted into 1-undecanol and the sample vial was cooled in an ice bath for 5 min.The solidified extract was transferred into a conical vial where it was melted immediately, and 20 µL of this solution was injected and analyzed by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). Several variables such as sample pH, the concentration of TPAS, volume of 1-undecanol and extraction time were investigated in details and optimum conditions were obtained. Under the optimum conditions, the Limit Of Detection (LOD) was 0.02 µg L-1 for lead and Relative Standard Deviation (RSD %) for five replicate determinations of 1 µg/L of lead was 5.6%. The results for determination of lead in reference material, three samples of wastewater, well, tap, river and aqueduct water demonstrated the accuracy, recovery, and applicability of the presented method.

Application of ultrasonically modified cloud point extraction method for simultaneous enrichment of cadmium and lead in sera of different types of gallstone patients

A novel and greener ultrasonically assisted/modified cloud point extraction procedure for the simultaneous preconcentration of lead and cadmium in serum samples of different types of gallstone patients was developed. The chelates of the under study metals, formerly formed with 8-hydroxyquinoline, were extracted in the micelles of a nonionic surfactant prior to analysis by flame atomic absorption spectrometer (FAAS). After the arrival of the cloud point, the critical micellar mass produced was homogenously dispersed in the aqueous phase with the help of ultrasound energy. The reliability of the developed procedure was tested by relative standard deviation (% RSD), which was found to be <5%. The performance of the proposed procedure was checked by applying to certified reference material and spiking standard in real samples. All the experimental parameters were optimized. The developed procedure of Um-CPE was applied successfully for the analysis of the target heavy metals in serum samples of different types of gallstone patients and referents. The higher levels of the understudy metals were observed in the patients as compared to the referents but the levels of the both metal were found to be considerably higher in patients with pigmented gallstones.

A new tunable dispersive liquid-liquid micro extraction method developed for the simultaneous preconcentration of lead and cadmium from lakes water: a multivariate study

A green tunable dispersive liquid-liquid micro extraction (TDLLME) technique was established for the simultaneous enrichment of lead (Pb) and cadmium (Cd) from different lakes water before analysis by flame atomic absorption spectrometry (FAAS). A solvent known as tunable polarity solvent (TPS), mixture of 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and 1-decanol, has been employed as extractant in aqueous medium. In first step this mixture can be made polar by slowly bubbling the antisolvent trigger (CO2) through the solution, which makes a monophasic solution. During this step hydrophobic complexes of the metals with 8-hydroxy quinoline (8-HQ) were extracted by TPS. Then the mixture was switched back to hydrophobic one by heating and/or bubbling nitrogen, turning the mixture into two phases again. In second phase the metals were leached out from the complexes entrapped in TPS, by treating with a solution of nitric acid and exposing the mixture to CO2, which switched the mixture into single phase. Then N2 purging and/or heating again turned the mixture into two phases. The acidic aqueous phase containing the metals was introduced to FAAS for analysis, whereas TPS was recycled for next experiment. Different parameters, affecting the efficiency the technique, were optimized by multivariate approach. The method was applied to certified reference material of water and to a real sample spiked with standards of known concentration, to confirm its validity and accuracy. LOD obtained for Pb and Cd were 0.560 and 0.056μgL−1 respectively. The developed method was applied successfully to the real water samples of two lakes of Sindh, Pakistan.

A Magnetized Nanoparticle Based Solid-Phase Extraction Procedure Followed by Inductively Coupled Plasma Atomic Emission Spectrometry to Determine Arsenic, Lead and Cadmium in Water, Milk, Indian Rice and Red Tea.

A sensitive and simple method using magnetic multi-walled carbon nanotube (MWCNTs-Fe3O4 MNP), as the adsorbent, has been successfully developed for extraction and pre-concentration of arsenic, lead and cadmium with detection by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The nanosorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction pattern (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). The key factors affecting the signal intensity such as pH, adsorbent amount, etc. were investigated. Under optimal conditions, the limits of detection (three-time of signal to noise ratio, S/N 3) were 0.3, 0.6, 0.3ng/mL for arsenic, lead and cadmium, respectively. Application of the adsorbent was investigated by the analysis of water, milk, Indian rice and red tea. The experimental data was analyzed and obeyed Langmuir and Freundlich adsorption models. The kinetic data was fitted to the pseudo-second-order model. Thermodynamic studies revealed the feasibility and exothermic nature of the system.

3D-printed flow system for determination of lead in natural waters

The development of 3D printing in recent years opens up a vast array of possibilities in the field of flow analysis. In the present study, a new 3D-printed flow system has been developed for the selective spectrophotometric determination of lead in natural waters. This system was composed of three 3D-printed units (sample treatment, mixing coil and detection) that might have been assembled without any tubing to form a complete flow system. Lead was determined in a two-step procedure. A preconcentration of lead was first carried out on TrisKem Pb Resin located in a 3D-printed column reservoir closed by a tapped screw. This resin showed a high extraction selectivity for lead over many tested potential interfering metals. In a second step, lead was eluted by ammonium oxalate in presence of 4-(2-pyridylazo)-resorcinol (PAR), and spectrophotometrically detected at 520nm. The optimized flow system has exhibited a linear response from 3 to 120µgL−1. Detection limit, coefficient of variation and sampling rate were evaluated at 2.7µgL−1, 5.4% (n=6) and 4 sampleh−1, respectively. This flow system stands out by its fully 3D design, portability and simplicity for low cost analysis of lead in natural waters.

Application of a new nanoporous sorbent for extraction and pre-concentration of lead and copper ions

ABSTRACTThe authors describe a method for the trace determination of copper (II) and lead (II) in water and fish samples using solid-phase extraction via siliceous mesocellular foam functionalised by dithizone. Siliceous mesocellular was functionalised with dithizone, and the resulting sorbent was characterised by scanning electron microscopy, surface area analysis, thermogravimetric/differential thermal analysis and FTIR. Following solid-phase extraction of target ions by the sorbent, copper and lead ions were quantified by flame atomic absorption spectrometry. Factors affecting the sorption and desorption of target ions by the sorbent were evaluated and optimised. The calibration plot is linear in the 1 – 500 μg L−1 copper (II) and 3–700 μg L−1 lead (II) concentration range. The relative recovery efficiency in real sample analysis is in the range from 96 to 102%, and precision varies between 1.7 and 2.8%. It is should be noted that the limits of detection for the copper and lead analysis were 0.8 and 1.6 μg L−1, respectively. Also, the adsorption capacities for copper and lead ions were 120 and 160 mg g−1, respectively. The obtained pre-concentration factor for the lead and copper ions by the proposed solid-phase extraction was 75. The method was successfully applied to the determination of low levels of copper (II) and lead (II) in tap, Caspian sea, Persian gulf and lake water and also their detection in fish samples.

Monitoring Pb in Aqueous Samples by Using Low Density Solvent on Air-Assisted Dispersive Liquid–Liquid Microextraction Coupled with UV–Vis Spectrophotometry

In this study, AA-DLLME combined with UV-Vis spectrophotometry was developed for pre-concentration, microextraction and determination of lead in aqueous samples. Optimization of the independent variables was carried out according to chemometric methods in three steps. According to the screening and optimization study, 86μL of 1-undecanol (extracting solvent), 12 times syringe pumps, pH 2.0, 0.00% of salt and 0.1% DDTP (chelating agent) were chosen as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R = 0.9994, and linearity range was 0.01-100µgmL-1. LOD and LOQ were 3.4 and 11.6ngmL-1, respectively. The method was applied for analysis of real water samples, such as tap, mineral, river and waste water.

Nonanoic Acid-Coated Magnetite Nanoparticles for Separation and Preconcentration of Lead and Copper in Tobacco Samples prior to Flame Atomic Absorption Spectrometry Determination

A new method using nonanoic acid-coated magnetic Fe3O4 nanoparticles as adsorbent has been developed for the single-step extraction and preconcentration of lead and copper in tobacco samples. Transmission electron microscopy and X-ray diffraction spectrometry were used to characterize the adsorbent. The experimental parameters affecting extraction efficiency, including amount of nanoparticles, volume of chelating reagents, sample pH, ultrasonic time and desorption conditions were investigated. The analytes desorbed from nanoparticles were determined by flame atomic absorption spectrometry. Under the optimum conditions, good linearity was obtained in the range of 2-400 µg L-1 for copper and 5-800 µg L-1 for lead (r > 0.998, p < 0.05). The limits of detection for copper and lead were 0.2 and 0.5 µg L-1, with enrichment factors of 45 and 52, respectively. The method was successfully employed to tobacco sample analysis and got excellent recoveries between 89.2 and 100.7% with relative standard deviations (n = 6) of 4.5-5.9%.