Absorption Spectrometric Determination Of Lead Research Articles

Fabrication and characterization of SiO2@Fe3O4@nanodiamonds for vortex-assisted magnetic solid-phase extraction of lead in cigarette samples prior to FAAS detection

A novel, speed and accurate vortex-assisted magnetic solid-phase extraction procedure for separation–preconcentration and flame atomic absorption spectrometric determination of lead at trace levels has been proposed. Silica-coated magnetic nanodiamonds (SiO2@MNDs) as magnetic solid-phase extractor were fabricated and characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectrometry and scanning electron microscopy. Pb(II) could be easily separated from the aqueous solution on the SiO2@MNDs by using a neodymium magnet. Analytical factors affecting the recoveries of Pb(II) such as pH, adsorbent amount, type and volume of eluent and sample volume were optimized. The preconcentration factor, the precision (RSD %, n = 5), the limit of detection and the limit of quantification were 5, 5.3%, 40.8 and 135 µg L−1, respectively. The effects of matrix ions have been investigated. The presented extraction method has been applied for the determination of lead in cigarette samples and Bush Branches and Leaves certified reference material. Quantitative recoveries changing from 94 to 106% were obtained for accuracy studies.

Synthesis and Characterization of Modified Multiwall Carbon Nanotubes With Poly (N-Phenylethanolamine) and Their Application for Removal and Trace Detection of Lead Ions in Food and Environmental Samples

This paper describes, a new, sensitive, and low-cost solid-phase extraction method using poly (N-phenylethanolamine)/multiwalled carbon nanotube (MWCNT) nanocomposite for extraction, preconcentration, and flame atomic absorption spectrometric determination of lead in food and water samples at trace levels. The poly (N-phenylethanolamine)/MWCNT nanocomposites were characterized by Fourier transformed infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) surface area (SBET), and scanning electron microscopy (SEM). Factors affecting the preconcentration of lead such as the pH of samples, flow rates, type and volume of eluent, and the effect of interfering ions and breakthrough volume on the separation and determination of lead ions were investigated. The optimum conditions for the adsorption step were 5.0 and 18 mL min−1 for pH and sample flow rate, respectively, and for desorption step, the optimal condition were 1.5 mL, 1 mol L−1 HCl, and 2 mL min−1, for volume of eluent, concentration of eluent, and eluent flow rate, respectively. The maximum sorbent capacity of the poly (N-phenylethanolamine)/MWCNT nanocomposite was calculated to be 152.1 mg g−1. The preconcentration factor, relative standard deviation, and limit of detection of the method were found to be 100, 3.1 % (10.0 μg L−1, n = 5), and 0.8 μg L−1, respectively. The presented method was validated by certified reference material (NIST SRM 1515 Apple leaves and IAEA-336 Lichen) and finally applied to analysis of lead ions in food (Citrus limetta, kiwi, pomegranate, and fish samples) samples. The obtained data for analysis of lead ions in food samples were in the concentration range of 4.1–50.8 μg kg−1.

Ionic liquid-linked dual magnetic microextraction of lead(II) from environmental samples prior to its micro-sampling flame atomic absorption spectrometric determination

A novel and rapid microextraction approach termed as ionic liquid-linked dual magnetic microextraction (IL-DMME), was developed for the atomic absorption spectrometric determination of lead. The developed method based on a combination of dispersive liquid–liquid microextraction (DLLME) and dispersive micro solid-phase extraction (D-μ-SPE). In the first DLLME step, 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], was selected to extract the lead-pyrrolidine-dithiocarbamate (Pb-PDC) complex from sample solution by the assistance of vortex agitator. After the first step, fifty milligrams of Fe3O4 magnetic nanoparticles (MNPs) were added to extraction of the ionic liquid and Pb-PDC complex in aqueous solution. The effective factors in proposed IL-DMME procedure, including volume of 1-butyl-3-methylimidazolium hexafluorophosphate, amount of Fe3O4 magnetic nanoparticles, vortex time, amount of ammonium pyrrolidinedithiocarbamate, sample volume and matrix effect were optimized in details. Under the optimal conditions, the method present has low detection limit (0.57μgL−1), high preconcentration factor (160) and good repeatability (<7.5%, n=10). The accuracy of the developed method was evaluated by the analysis of the certified reference materials and addition-recovery tests. The method was successfully applied to the determination of lead in water, plant and hair samples.

MWCNT/nano-ZrO_2 as a new solid phase extractor: its synthesis, characterization, and application to atomic absorption spectrometric determination of lead

Nanoscale ZrO_2 was synthesized on a multiwall carbon nanotube (MWCNT) and designed as a new solid phase extractor for metal ion preconcentration. The characterization of the synthesized material was achieved by transmission electron microscope (TEM) and X-ray diffraction (XRD). Then the new nanoscale material was applied to preconcentration of lead(II) from various matrices. Different experimental factors including pH of the sample solution, sample volume, flow rate of the sample solution, and volume and concentration of the eluent for the preconcentration step were examined. The effect of interfering ions on the recovery of the lead(II) was also investigated. The recovery of lead(II) under the optimum conditions was found to be 104 \pm 2% at 95% confidence level. The preconcentration factor was 30 when 150 mL of sample solution and 5 mL of eluent were used. The analytical detection limit for Pb(II) was 0.80 \mu g L^{-1} after preconcentration. The adsorption capacity of the new nanosorbent was 115 mg g^{-1}. The accuracy of the method was confirmed by analyzing standard reference materials (Silty Clay 7003). The results demonstrated good agreement with the certified values. The method was applied for the determination of lead in tap water and clay samples.

Rapid coprecipitation-separation and flame atomic absorption spectrometric determination of lead and cadmium in water with cobalt (II) and ammonium pyrrolidine dithiocarbamate

A coprecipitation technique which does not require complete collection of the precipitate was proposed for the determination of trace lead and cadmium in water with flame atomic absorption spectrometry (FAAS) after preconcentration of lead and cadmium by using cobalt (II) and ammonium pyrrolidine dithiocarbamate (Co-APDC) as coprecipitant and known amount of cobalt as an internal standard. Since lead, cadmium and cobalt were well distributed in the homogeneous precipitate, the concentration ratio of lead to cobalt, and cadmium to cobalt remained unchanged in any part of the precipitate. The amount of lead and cadmium in the original sample solution can be calculated respectively from the ratio of the absorbance values of lead and cadmium to cobalt in the final sample solution that is measured by FAAS and the known amount of the lead and cadmium in the standard series solutions. The optimum pH range for quantitative coprecipitation of lead and cadmium is from 3.0 to 4.5. The 16 diverse ions tested gave no significant interferences in the lead and cadmium determination. Under optimised conditions, lead ranging from 0 to 40 µg and cadmium ranging from 0 to 8 µg were quantitatively coprecipitated with Co-APDC from 100 mL sample solution (pH ∼ 3.5). This coprecipitation technique coupled with FAAS was applied to the determination of lead and cadmium in water samples with satisfactory results (recoveries in the range of 94.0–108%, relative standard deviations <6.0%).

Studies on Formation and Thermal Decomposition of Lead Hydride, PbH4

In the present work, some fundamental aspects of the formation of gaseous lead hydride from aqueous solutions containing divalent lead ions (Pb2+) and its application in the atomic absorption spectrometric analysis lead has been investigated. By utilizing a peristaltic pump, an acidic solution of Pb2+ was first oxidized with ammonium peroxodisulphate, NH4S2O8, and followed by reduction with sodium tetrahydroborate, NaBH4. After a gas-liquid separation, the gaseous lead hydride produced was directly swept into an electrically heated open ended quartz tube, located at the light path of an atomic absorption spectrometer in order to have possibilities for specific atomic absorption spectroscopic measurements. The absorbance signals caused by lead atomic absorption could be used proportionally to estimate the density of atomic lead vapor produced in the thermal decomposition under investigation. Results showed that on-line pre-oxidation of the analyte is very important and crucial step in the gaseous hydride generation of lead, and no lead hydride was produced without the involvement of this step. Moreover, it was observed that the use of low major gas flows cannot be applied in quantitative atomic absorption spectrometric determination of lead by this technique. This condition may result in possible losses of the analyte atomic vapor due to metallic condensation.

Tetradecyl(trihexyl)phosphonium chloride ionic liquid single-drop microextraction for electrothermal atomic absorption spectrometric determination of lead in water samples

A highly efficient single-drop microextraction (SDME) procedure using a low-cost room temperature ionic liquid (RTIL), i.e., tetradecyl(trihexyl)phosphonium chloride (CYPHOS IL 101), for Pb determination at trace levels in real water samples was developed. Lead was chelated with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) reagent and extracted into a 4 microL microdrop of CYPHOS IL 101. The RTIL drop was directly injected into the graphite furnace of the electrothermal atomic absorption spectrometer (ETAAS). Under optimal microextraction conditions, a preconcentration factor of 32 was achieved with only 1.5 mL of sample resulting in a phase-volume ratio of 375. The limit of detection (LOD) obtained was 3.2 ng L(-1) and the relative standard deviation (RSD) for 10 replicates at 0.5 microg L(-1) Pb(2+) concentration level was 4.9%, calculated at peak heights. The calibration graph was linear from concentration levels near the detection limits up to at least 4.5 microg L(-1) with a correlation coefficient of 0.9996. The accuracy of the methodology was evaluated by analysis of a certified reference material (CRM). The method was successfully applied to the determination of Pb in tap, mineral, well and river water samples.

Flotation separation and electrothermal atomic absorption spectrometric determination of lead in water samples

A flotation method based on formation of an ion–associate complex between ferroin and Pb(II)–thiosulfate complex is proposed for the quantitative separation and preconcentration of Pb(II) content in water and some vegetable samples. The flotation process was carried out using a 250-mL aliquot of the aqueous solution at a buffering pH of 8.50. After separating the ion–associate complex, it was dissolved in 5 mL of heated 1 M HNO3, and the Pb(II) content was determined by electrothermal atomic absorption spectrometry. The determination of Pb(II) was carried out in the range of 1.6 × 10−9 to 1.2 × 10−8 M. The limit of detection and relative standard deviation were obtained as 8.5 × 10−10 M and 1.73%, respectively. It was found that a large number of cations and anions, even at high much foreign ion/Pb(II) ratios, were not interfered. The validity of the method was confirmed by determining the Pb(II) contents in two Standard Reference Materials and a synthetic liquid extract of vegetable sample. It was then applied satisfactorily for determination of Pb(II) in several plant foodstuffs, drinking-water, and tap-water samples.

Cloud point extraction procedure for flame atomic absorption spectrometric determination of lead(II) in sediment and water samples

The conditions for cloud point extraction of lead(II) from aqueous solutions were investigated and optimized. The procedure is based on the separation of Pb(II) – brillant cresyl blue (BCB) complexes into the micellar media by adding the surfactant Triton X-114. After phase separation, the surfactant-rich phase was dissolved with 1 mol L−1 HNO3 in ethanol and diluted with 1 mol L−1 HNO3 solution before lead was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities, incubation time, temperature, viscosity, sample volume, and interfering ions was performed. The effects of the matrix ions were also examined. The detection limits for three times the standard deviations of the blank for lead were 7.5 µg L−1 for water samples and 0.33 µg g−1 for sediment samples. The validity of cloud point extraction was checked by employing certified reference samples of Lake Sediment IAEA-SL-1 and Sewage Sludge BCR-CRM 144R. The procedure was applied to natural waters and sediment samples with satisfactory results (recoveries >95%, relative standard deviations <6.4%).

XAD‐4/PAN Solid Phase Extraction System for Atomic Absorption Spectrometric Determinations of Some Trace Metals in Environmental Samples

A simple, fast, and sensitive column solid phase extraction study has been proposed for flame atomic absorption spectrometric determination of lead, cadmium, chromium, nickel, copper, and manganese ions on XAD‐4 as 1‐(2‐pyridylazo)2‐naphthol (PAN) complexes. The analytes were sorbed as PAN complexes on Amberlite XAD‐4 column at the pH range of 8.5–10, and then eluted with 1 M HNO3 in acetone. The effect of pH, reagent amount, sample volume, and matrix of the sample on the sorption of metal ions has also been investigated. The concentration of analytes after separation and preconcentration was in agreement with the added amount of ions. The present method was found to be applicable to the preconcentration of analyte ions in river water from Yesilirmak, lake water from Lake Van, bottled mineral waters, tap water, stream sediment, mushroom, tobacco, and black tea samples with good results (recoveries greater than 95%, relative standard deviations lower than 10%).

Atomic Absorption Spectrometric Determination of Lead and Cadmium in Waste Water Samples After Enrichment and Separation Using Purolite C-100 E Resin Filled in a Syringe-Mountable Filter

Abstract In this study a new hopeful enrichment/separation technique to substitute for batch and column techniques is described. Lead and cadmium were selected as analyte elements. The housing of a syringe mountable membrane filter was filled with Purolite C-100 E cationic resin and mounted to the tip of a plastic syringe. If the sample solution was drawn into the syringe in about 30 s passing through the resin and discharged again for the same length of time, the analyte elements were quantitatively retained at pH ≥ 2. The elements sorbed by the resin were then quantitatively eluted by drawing and discharging 2.5 M HCl as eluent, again at the same flow rates as those used in retention. The recoveries of Pb and Cd were 98.2 and 99%, respectively, with relative standard deviations of around ± 2%. Detection limits (3δ) were 15 µgL−1 for Pb and 10 µgL−1 for Cd. The elements could be concentrated by drawing and discharging several portions of sample successively but eluting only once. Pb and Cd in spiked wast...

Atomic Absorption Spectrometric Determination of Lead after Extraction and Preconcentration with 5-Br-PADAP

Lead is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 4.0-6.0 from a large volume of aqueous solutions of various samples with preconcentration factor of 60. After filtration, the solid mass consisting of the lead complex and naphthalene was dissolved with 5 mL of dimethylformamide and the metal was determined by atomic absorption spectrometry. The calibration curve is linear in the range of 1.9-180 mg/mL in DMF with a relative standard deviation 1.7&. The interference of a large number of anions and cations has been studied.

Separation and preconcentration of trace amounts of lead on octadecyl silica membrane disks modified with a new S-containing Schiff's base and its determination by flame atomic absorption spectrometry

A synthetic procedure was developed for the preparation of a new S-containing Schiff's base [ethane amine, N, N′-bis(2-thienyl methylene)]. The resulting compound (L) was used as a modifier in octadecyl silica membrane disks for solid phase extraction and flame absorption spectrometric determination of lead in water samples. Extraction efficiency and influence of flow rates, pH, type and minimum amount of stripping acid were investigated. The maximum capacity of the membrane disks modified by 5 mg of the (L) used was found to be 700 μg Pb 2+. The limit of detection of the proposed method is 16.7 ng ml −1. The method was applied to the recovery of Pb 2+ ions from different synthetic samples and spring water samples.

Minicolumn field sampling and flow‐injection‐atomic absorption spectrometric determination of lead in seawater

AbstractA simple field‐flow preconcentration system has been developed for lead determination in seawater. Seawater samples are collected in situ by passing them with a pump through minicolumns packed with poly(aminophosphonic acid) chelating resin to retain and preconcentrate lead, and remove the saline matrix. Minicolumns loaded with lead are then returned to the laboratory where they are inserted into a flow‐injection system and eluted with a small volume of hydrochloric acid into the nebulizer‐burner system of a flame atomic absorption spectrometer. The detection limit for lead in seawater was 2.8 ng l−1. This procedure was applied to the determination of lead in seawater samples from Galicia (Spain). © 2001 John Wiley &amp; Sons, Inc. Field Analyt Chem Technol 5: 239–243, 2001

Graphite Furnace Atomic Absorption Spectrometric Determination of Lead and Cadmium Extracted from Ceramic Foodware: Collaborative Study

A modification of the official flame atomic absorption spectrometric (FAAS) method for determining lead and cadmium extracted from ceramic foodware was collaboratively studied. In the modified method, graphite furnace atomic absorption spectrometry (GFAAS) is substituted for FAAS. The modified method also includes mandatory quality control procedures to improve method performance. The extraction procedure of the official method (leaching with 4% acetic acid for 24 h at room temperature) remains unchanged. Seven laboratories analyzed blind duplicate portions of 3 ceramicware leach solutions containing Pb at concentrations of 0.0196, 0.403, and 3.73 microg/mL and Cd at concentrations of 0.00236, 0.0456, and 0.544 microg/mL. Performance of the modified method compared well with that of the official method. The repeatability relative standard deviation (RSDr) ranged from 0.87 to 6.7% for Pb and from 3.7 to 11% for Cd. The reproducibility relative standard deviation (RSDR) ranged from 4.5 to 12% for Pb and from 7.0 to 11% for Cd. Accuracy of collaborator results was 97-98% for Pb and 93-101% for Cd. Quality control results and quantitation limits were excellent. Method quantitation limits varied among laboratories from 0.005 to 0.019 microg/mL for Pb and from 0.0004 to 0.0019 microg/mL for Cd. The modified method was adopted First Action by AOAC INTERNATIONAL.

Flame atomic absorption spectrometric determination of lead in waste water and effluent after preconcentration using a rapid coprecipitation technique with gallium phosphate.

A determination method for lead in waste water and effluent was studied using flame atomic absorption spectrometry after preconcentration of lead by the rapid coprecipitation technique with gallium phosphate. Lead ranging from 0.5 to 50 microg was quantitatively coprecipitated with gallium phosphate from 100-150 mL sample solution (pH approximately 5). The presence of gallium phosphate did not affect the atomic absorbance of lead. Since the concentration of gallium in the final sample solution is also measurable by flame atomic absorption spectrometry at 250.0 nm without further dilution, the rapid coprecipitation technique, which does not require complete collection of the precipitate, becomes possible using a known amount of gallium and measuring the concentrations of both lead and gallium in the final sample solution by flame atomic absorption spectrometry. The 32 diverse ions tested gave no significant interferences in the lead determination. The method proposed here is rapid and has good reproducibility.

Rapid determination of lead and cadmium in biological fluids by electrothermal atomic absorption spectrometry using Zeeman correction

Procedures for the electrothermal atomic absorption spectrometric determination of lead and cadmium in urine, serum and blood are developed. For serum and blood, the samples are diluted by incorporating 0.015% (w/v) Triton X-100 and 0.1% (w/v) ammonium dihydrogenphosphate to the solutions, which are then introduced directly into the furnace. A solution containing 15% (w/v) hydrogen peroxide and 0.65% (w/v) nitric acid is also introduced into the atomizer by means of a separate injection. Zeeman-based correction is recommended. Both conventional and fast-heating programs are discussed. Calibration is carried out using the standard additions method. The reliability of the procedures is checked by analyzing three certified reference materials and by recovery studies.

Electrothermal atomic absorption spectrometric determination of lead, cadmium, copper and zinc in high-salt content samples after simultaneous separation on polyethylene powder impregnated with 1-(2-pyridylazo)-2-naphthol: application to the analysis of hemodialysis fluids

A simultaneous separation and preconcentration of lead, cadmium, zinc and copper from high-salt content matrices for subsequent electrothermal atomic absorption spectrometric determination was developed. The metals were preconcentrated on a micro-column filled with polyethylene powder impregnated with the complexing agent 1-(2-pyridylazo)-2-naphthol. The determinations, without the interference of the saline matrix, were carried out after metals elution with a small volume of an ethanolic solution of nitric acid. The saline matrices were sodium, potassium, magnesium and calcium chlorides, sodium acetate and bicarbonate, which constitute concentrates for hemodialysis. The immobilisation capacity of the complexing agent is about 2.5 µmol per gram of polyethylene and the column capacity with respect to each metal is about 0.75 µmol per gram resin for copper, cadmium and zinc and 0.25 µmol per gram for lead. For the optimisation of the procedure, effects of sample flow rate and pH, eluent composition and concentration, and the influence of salts on the complexation of the metals were investigated. The proposed method was characterised by a precision of about 95% (n = 3) and recoveries from spiked samples of the salts were 81–112%. All results were in agreement with those obtained by anodic stripping voltammetry, the technique used for comparison. The method was applied to the analysis of saline concentrates for hemodialysis, where the investigated metals were found in concentrations between 3.1 µg l–1 for cadmium and 90.5 µg l–1 for zinc.

Electrothermal atomic absorption spectrometric determination of lead in calcium drug samples by direct atomization technique

The direct determination of lead in calcium drug samples by electrothermal atomic absorption spectrometry (ETAAS) with a molybdenum tube atomizer has been developed. Direct calibration with lead standard solutions together with matrix elements (CaHPO 4 or CaCo 3) and ultrasonic agitation of a solution including the sample powder were used. Thiourea served as a matrix modifier to eliminate the interference of matrix elements. Analytical results obtained from four calcium drug samples by direct atomization are in good conformity with the dissolved acid digested samples. Advantages of this method are simplicity, rapid calibration, fast analysis and low cost.

Effect of refractory element carbide coating of a pyrolytically coated graphite furnace on injectable sample volume in the electrothermal atomic absorption spectrometric determination of lead

The effect of treating the surface of a pyrolytically coated graphite furnace with various refractory elements, such as Hf, Nb, W and Zr, on the injectable sample volume was evaluated in order to enhance the sensitivity. Treatment with W made it possible to introduce a 100 µl aliquot of sample solution into the furnace with a high precision (RSD 0.99) between integrated absorbance and injection volume was observed in the range 0–100 µl. Use of a Pd modifier made it possible to enhance the precision (RSD <2%) and the stability of the integrated absorbance (RSD <2.5%) for up to 250 firings. A good linearity was also observed. The calculated detection limit and characteristic mass (sensitivity) were 0.02 µg l–1 and 12 pg, respectively, for a 100 µl injection with the Pd modifier at the optimum ashing temperature of 1400 °C. An interference study was also carried out. The recoveries of 2 µg l–1 Pb added to various water samples, such as snow, rain, river water and tap water were 96–106%.