Coprecipitation of lead and cadmium using copper(II) mercaptobenzothiazole prior to flame atomic absorption spectrometric determination

A coprecipitation method using a combination of 2-mercaptobenzothiazole (MBT) as a chelating reagent and copper as the coprecipitate carrier is described for the determination of trace lead and cadmium by flame atomic absorption spectrometry. The coprecipitation conditions, such as the effect of pH, the amount of carrier element and reagent, standing time, sample volume and matrix effects were examined in detail. It was found that lead and cadmium are coprecipitated quantitatively (≥95%) with Cu(II)-MBT at pH 9 and that the relative standard deviations (n = 7) were ≤1.6%. When using the enrichment factors of 150-fold for lead and cadmium, the detection limits (3s/b) obtained are 1.08 for lead and 0.04 μg L⁻¹ for cadmium. The method was validated with spiked sea water, stream water, well water, and vegetable samples.     

Solid phase extraction of trace cadmium and lead in food samples using modified peanut shell prior to determination by flame atomic absorption spectrometry

Microchimica Acta - Peanut shell was chemically modified with phosphoric acid and used as a solid phase extraction material for the determination of trace amounts of Pb2+ and Cd2+ in food samples...     

1,8-Dihydroxyanthraquinone anchored on silica gel: synthesis and application as solid phase extractant for lead(II), zinc(II) and cadmium(II) prior to their determination by flame atomic absorption spectrometry

A new chelating matrix has been prepared by immobilizing 1,8-dihydroxyanthraquinone (DHAQ) on silica gel modified with (3-aminopropyl)triethoxysilane. After characterizing the matrix with thermogravimetric analysis (TGA), cross polarization magic angle spinning (CPMAS) NMR and diffuse reflectance infrared fourier transformation (DRIFT) spectroscopy, it has been used to preconcentrate Pb(II), Cd(II) and Zn(II) prior to their determination by flame atomic absorption spectrometry. The optimum pH ranges for quantitative sorption are 6.0-7.5, 7.0-8.0 and 6.0-8.0 for Pb, Zn, and Cd, respectively. All the metal ions can be desorbed with 2 mol l(-1) HCl/HNO(3). The sorption capacity of the matrix has been found to be 76.0, 180.0 and 70.2 mumol g(-1) for Pb, Zn and Cd, respectively, with the preconcentration factor of approximately 200. The limits upto which electrolytes NaNO(3), NaCl, NaBr, Na(2)SO(4), Na(3)PO(4) sodium citrate, EDTA, glycine and humic acid and cations Ca(II), Mg(II), Cu(II), Co(II), Ni(II), Mn(II) Al(III), Cr(III) and Fe(III) can co-exist with the metal ions during their sorption without any adverse effect are reported. The lowest concentration of metal ions for quantitative recovery is 5.0 ng ml(-1) The simultaneous enrichment and determination of all the metals is possible if total load of metal ions is less than sorption capacity. The flame AAS was used to determine these metal ions in underground, tap and river water samples (relative standard deviation (R.S.D.)相似文献   

Enrichment of iron(III), cobalt(II), nickel(II), and copper(II) by solid-phase extraction with 1,8-dihydroxyanthraquinone anchored to silica gel before their determination by flame atomic absorption spectrometry

A chelating matrix prepared by immobilizing 1,8-dihydroxyanthraquinone on silica gel modified with 3-aminopropyltriethoxysilane has been characterized by use of cross-polarization magic angle spinning (CPMAS) NMR, diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy, and thermogravimetric analysis and used to preconcentrate Fe(III), Co(II), Ni(II), and Cu(II) before their determination by flame atomic absorption spectrometry. The optimum pH ranges for quantitative sorption are 6.5-8.0, 6.0-7.0, 6.0-8.0, and 7.0-8.5 for Cu, Fe, Co, and Ni, respectively. All the metal ions can be desorbed with 2 mol L(-1) HCl or HNO3. The sorption capacity ( micromol g(-1) matrix) and preconcentration factor were 226.6, 250; 365.6, 300; 101.8, 150; and 109.0, 250 for Cu, Fe, Co, and Ni, respectively. The lowest concentration for quantitative recovery was 4.0, 3.3, 6.6, and 4.0 ng mL(-1), respectively for the four metal ions. The limits up to which electrolytes NaNO3, NaCl, NaBr, Na2SO4, and Na3PO4 and cations Ca(II) and Mg(II) can coexist with the four metal ions during their sorption without adverse effect are reported. The simultaneous enrichment and determination of all the four metals is possible if the total load of metal ions is less than the sorption capacity. Flame AAS was used to determine the metal ions in underground, tap, and river water samples (RSD相似文献   

Solid phase extraction of Pd(II) on a newly synthesized chelating resin prior to determination by flame atomic absorption spectrometry

A new solid phase extraction method for the separation and preconcentration of Pd(II) was developed. As solid phase material, a new chelating polymer, poly [N-(4-bromophenyl)-2-methacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid - co-divinylbenzene] was synthesized. The parameters such as the effect of pH, eluent type, volume and concentration, flow rate of sample solution, sample volume and effect of interfering ions for the preconcentration of Pd(II) were investigated. The optimum pH was found to be 9. Eluent for quantitative elution was 10 mL of 1 mol L^?1 HCl. The preconcentration factor of the method was 75. At optimum conditions, the recovery for Pd(II) was found to be 101?±?4%. The limit of detection (3σ) was 1.1?µg L^?1. The method was applied to the determination of palladium in tap water and converter samples with satisfactory results.     

Solid phase extraction of trace amounts of silver (I) using dithizone-immobilized alumina-coated magnetite nanoparticles prior to determination by flame atomic absorption spectrometry

A new, simple, fast and reliable solid-phase extraction (SPE) method has been developed to separation/preconcentration of trace amounts of silver ion from environmental water samples using dithizone/sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (DTZ/SDS-ACMNPs) and its determination by flame atomic absorption spectrometry. The coating of alumina on Fe₃O₄ NPs not only avoids the dissolving of Fe₃O₄ NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of DTZ/SDS-ACMNPs with an adscititious magnet. Optimal experimental conditions including amount of DTZ/SDS, pH value, standing time, sample volume, type, volume and concentration of eluent and co-existing ions have been studied and established. Under the optimal experimental conditions, the detection limit for Ag(I) with enrichment factors of 100 was found to be 0.52?ng?mL^?1 and its relative standard deviations (RSD) was 3.4% (n?=?10, C?=?5.0?µg?mL^?1). The linear range of calibration curve for Ag(I) was 2–5000?ng?mL^?1 with a correlation coefficient of 0.9991. The proposed method was successfully applied to the determination of target analyte in different water and wastewater samples. The validity of the method has been checked by applying it to study the recovery of silver ion in spiked water and wastewater samples.     

Solid phase extraction and determination of ultra trace amounts of copper(II) using octadecyl silica membrane disks modified by 11-hydroxynaphthacene-5,12-quinone and flame atomic absorption spectrometry

A simple and selective method for rapid extraction and determination of trace amounts of copper(II) ions using octadecyl-bonded silica membrane disks modified with 11-hydroxynaphthacene-5,12-quinone and flame atomic absorption spectrometry is presented. Extraction efficiency and the influence of pH, flow rates, amount of ligand and type and least amount of stripping acid were evaluated. Maximum capacity of the membrane disks modified by 5 mg of the ligand was found to be 360 mug of Cu(2+) ion. The break through volume is larger than 2000 ml. The limit of detection of the proposed method is 0.2 ng ml(-1). The effects of various cationic interferences on the percent recovery of copper in binary mixtures were studied. The method was applied to the recovery of Cu(2+) ions from four different water samples and a synthetic sample.     

Functionalized HMS mesoporous silica as solid phase extractant for Pb(II) prior to its determination by flame atomic absorption spectrometry

In this work, a mesoporous silica has been chemically modified with 5-mercapto-1-methyl-1-H-tetrazol using the homogeneous route (MTTZ-HMS). This synthetic route involved the reaction of 5-mercapto-1-methyl-1-H-tetrazol with 3-chloropropyltriethoxysilane, prior to immobilization on the support. The resulting material has been characterized and employed as solid phase extractant for Pb(II). The effect of several variables (stirring time, pH, temperature, metal concentration, presence of other metals) has been studied using batch and column techniques. In batch experiments, 15 min stirring time, 55 degrees C and pH 8 were the optimal conditions for Pb(II) adsorption. In column experiments, sorption was quantitative for 1000 mL of 2.41 x 10(-4 )mM of Pb(II) solution and adsorbed ions were eluted out by 5 mL of 1 M HCl (preconcentration factor of 200). Spiked tap water was used for the preconcentration and determination of Pb(II) by flame atomic absorption spectrometry, and a 100% recovery was obtained. The LOD and LOQ values of the proposed method were found to be 3.52 x 10(-3) and 4.20 x 10(-3 )mM, respectively. The RSD for three preconcentration experiments was found to be 相似文献   

Use of silica gel chemically modified with zirconium phosphate for preconcentration and determination of lead and copper by flame atomic absorption spectrometry

An analytical method using silica gel chemically modified with zirconium (IV) phosphate for preconcentration of lead and copper, in a column system, and their sequential determination by flame atomic absorption spectrometry (FAAS), was developed. Sample solutions are passed through a glass column packed with 100 mg of the sorbent material, at pH 4.5, and lead and copper are eluted with 1.0 mol l⁻¹ HNO₃ at a flow rate of 2.0 ml min⁻¹. The extraction of copper is affected by Fe(II), Mn(II), Zn(II), Ni(II) and Co(II) while only Fe(II) interferes in the lead determination. These interferences may be overcome with an appropriate addition of a KI or NaF solution. An enrichment factor of 30 was obtained for both metals. While the limits of detection (3σ) were 6.1 and 1.1 μg l⁻¹, for Pb and Cu, respectively, the limits of determination were 16.7 and 3.3 μg l⁻¹. The precision expressed as relative standard deviation (R.S.D.) obtained for 3.3 μg l⁻¹ of Cu and 16.7 μg l⁻¹ of Pb were 4.3 and 4.7%, respectively, calculated from ten measurements. The proposed method was evaluated with reference material and was applied for the determination of lead and copper in industrial and river waters.     

Graphene oxide-packed micro-column solid-phase extraction combined with flame atomic absorption spectrometry for determination of lead (II) and nickel (II) in water samples

A sensitive and simple method has been established for simultaneous preconcentration of trace amounts of Pb (II) and Ni (II) ions in water samples prior to their determination by flame atomic absorption spectrometry. This method was based on the using of a micro-column filled with graphene oxide as an adsorbent. The influences of various analytical parameters such as solution pH, adsorbent amount, eluent type and volume, flow rates of sample and eluent, and matrix ions on the recoveries of the metal ions were investigated. Using the optimum conditions, the calibration graphs were linear in the range of 7–260 and 5–85 μg L^?1 with detection limits (3S_b) of 2.1 and 1.4 μg L^?1 for lead and nickel ions, respectively. The relative standard deviation for 10 replicate determinations of 50 μg L^?1 of lead and nickel ions were 4.1% and 3.8%, respectively. The preconcentration factors were 102.5 and 95 for lead and nickel ions, respectively. The adsorption capacity of the adsorbent was also determined. The method was successfully applied to determine the trace amounts of Pb (II) and Ni (II) ions in real water samples. The validation of the method was also performed by the standard reference material.     

Solid phase extraction of copper (II) by sorption on octadecyl silica membrane disk modified with a new Schiff base and determination with atomic absorption spectrometry

A simple, selective and reliable method for rapid extraction and determination of trace amounts of Cu (II) ions from aqueous samples using octadecyl-bonded silica membrane disks modified with bis-(3-methoxy salicylaldehyde)-1,6-diaminohexane and flame atomic absorption spectrometry (FAAS) is presented. Extraction efficiency, the influence of pH, flow rates, amount of ligand, and type and least amount of eluant were investigated. The linear dynamic range of the proposed method for Cu (II) ions was found in a wide concentration range of 1.0 (± 0.2)–150 (± 2) μg l^− 1. The detection limit and preconcentration factor of this method were found 30.0 (± 0.7) ng l^− 1 and 100 respectively. The reproducibility of the procedure is at the most 2.0%. The effects of various cationic interferences on the percent recovery of copper ion were studied. The method was used to the recovery of copper ion from different synthetic, alloys and biological samples.     

Solid-phase extraction of bismuth, lead and nickel from seawater using silica gel modified with 3-aminopropyltriethoxysilane filled in a syringe prior to their determination by graphite furnace atomic absorption spectrometry

In this study, the use of syringe filled with sorbent for the separation and enrichment of bismuth, lead and nickel prior to their analysis by graphite furnace atomic absorption spectrometry was described to substitute for batch and column techniques. The method proposed in this paper was compared with column technique with respect to easiness, fastness, simplicity, recovery and risk of contamination. The syringe was filled with 0.5 g of sorbent and in order to retain the analyte elements, 5 ml of sample solution (pH≥5) was drawn into the syringe to 15 s and discharged again in 15 s. Then, 2.0 M of HCl, as the eluent, was drawn into the syringe and ejected back to desorb the analyte elements. At optimum conditions, the recoveries of Bi, Pb and Ni were 95-99% with relative standard deviations (RSDs) of around ±2%. Detection limit (δ) was 0.5 μg l⁻¹ for Bi, Pb and Ni, respectively. The elements could be concentrated by drawing and discharging several portions of sample successively but eluting only one time. Bi, Pb and Ni added to a seawater sample were quantitatively recovered (>95%) with low RSD values of around ±2-3%. The risk of contamination is less than that with the column technique. In addition, it is much faster, simpler, easier, more practical and handy compared with column technique.     

Simultaneous preconcentration of copper, nickel, cobalt and lead ions prior to their flame atomic absorption spectrometric determination

A sensitive and simple method for the simultaneous preconcentration of nutritionally important minerals in real samples has been reported. The method is based on the adsorption of Cu2+, Ni2+, Co2+ and Pb2+ on 4-propyl-2-thiouracil (PUT) loaded on activated carbon. The metals on the complexes are eluted using 5 mL 3 M HNO3 in acetone. The influences of the analytical parameters including pH and sample volume were investigated. The effects of matrix ions on the retentions of the analytes were also examined. The recoveries of analytes were generally higher than 95%. The detection limits for Cu2+, Ni2+, Co2+ and Pb2+ were 1.6, 1.3, 1.2, 2.3 ng ml(-1), respectively. The method has been successfully applied for these metals content evaluation in some real samples including natural water samples.     

微波消解-原子吸收光谱法连续测定仿真饰品中铅镉镍含量

采用HNO3-HF-HCl酸体系消解样品,火焰原子吸收光谱法连续测定非金属材质仿真饰品中的铅、镉和镍。优化了仪器工作参数和消解条件,进行了共存离子的干扰试验。方法检出限分别为铅5.7 mg/kg、镉0.3 mg/kg、镍3.5 mg/kg。实际样品测定的相对标准偏差(n=6)为1.6%～5.2%,回收率为86.0%～105.8%。     

Thioacetamide chemically immobilized on silica gel as a solid phase extractant for the extraction and preconcentration of copper(II), lead(II), and cadmium(II)

Thioacetamide immobilized on silica gel was prepared via the Mannich reaction. The extraction and enrichment of copper(II), lead(II), and cadmium(II) ions from aqueous solutions has been investigated. Conditions for effective extraction are optimized with respect to different experimental parameters in both batch and column processes prior to their determination by flame atomic absorption spectrometry (FAAS). The optimum pH ranges for quantitative adsorption are 4.0-8.0, 2.0-7.0, and 5.0-10.0 for Pb(II), Cu(II), and Cd(II), respectively. Pb(II) and Cd(II) can be desorbed with 3 mol/L and 0.1 mol/L HCl/HNO3, and Cu(II) can be desorbed with 2.5% thiourea. The adsorption capacity of the matrix has been found to be 19.76, 16.35, and 12.50 mg/g for Pb(II), Cu(II), and Cd(II), respectively, with the preconcentration factor of approximately equal to 300 for Pb(II) and approximately equal to 200 for Cu(II) and Cd(II). Analytical utility is illustrated in real aqueous samples generated from distilled water, tap water, and river water samples.     

Separation and preconcentration of Pb(II) using ionic liquid-modified silica and its determination by flame atomic absorption spectrometry

A new method based on microcolumn packed with ionic liquid-modified silica combined with flame atomic absorption spectrometry has been developed for the determination of lead in environmental samples. Several factors influencing the preconcentration efficiency of lead and its subsequent determination, such as pH of the sample, flow rate, mass of ionic liquid, and interfering effect, have been investigated. Lead could be quantitatively retained by ionic liquid-modified silica in the pH range of 5-7, and then eluted completely with 3.0 mL 1.0 mol L⁻¹ HCl. The detection limit of this method for lead was 0.7 μg L⁻¹ with preconcentration factor of 185, and the relative standard deviation (RSD) was 4.2% at 0.1 μg mL⁻¹ Pb(II). This method has been applied for the determination of trace amount of lead in NIST standard reference material 2709 (San Joaquin Soil) and river water samples with satisfactory results.     

Cloud point extraction for the determination of cadmium and lead employing sequential multi-element flame atomic absorption spectrometry

A cloud point extraction procedure for pre-concentration and determination of cadmium and lead in drinking water using sequential multi-element flame atomic absorption spectrometry is described. 4-(2-thiazolylazo)-orcinol (TAO) has been used as complexing agent and the micellar phase was obtained using the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The conditions for reaction and extraction (surfactant concentration, reagent concentration, effect of incubation time, etc) were studied and the analytical characteristics of the method were determined. The method allows the determination of cadmium and lead with quantification limits of 0.30?µg?L^?1 and 2.6?µg?L^?1, respectively. A precision expressed as relative standard deviation (RSD, n?=?10) of 2.3% and 2.6% has been obtained for cadmium concentrations of 10?µg?L^?1 and 30?µg?L^?1, respectively, and RSD of 1.3% and 1.7% for lead concentrations of 10?µg?L^?1 and 30?µg?L^?1, respectively. The accuracy was confirmed by analysis of a natural water certified reference material. The method has been applied for the determination of cadmium and lead in drinking water samples collected in the cities of Ilhéus and Itabuna, Brazil. Recovery tests have also been performed for some samples, and results varied from 96 to 105% for cadmium and 97 to 106% for lead. The cadmium and lead concentrations found in these samples were always lower than the permissible maximum levels stipulated by World Health Organization and the Brazilian Government.     

Flow injection sorbent extraction with dialkyldithiophosphates as chelating agent for the determination of cadmium, copper and lead by flame atomic absorption spectrometry

Using octadecyl functional groups (C₁₈) bonded to silica gel as sorbent and methanol as eluent, the flow injection sorbent extraction features of dialkyldithiophosphates (RO)₂P(S)S⁻ as the chelating agent for cadmium, copper and lead was investigated in respect of the effects of pH, alkyl substituent group, reagent concentration and masking agent, with flame atomic absorption spectrometric detection. The elements are quantitatively extracted with the short-alkyl-chain reagents (R up to propyl) in acidic medium. The extractability decreases with the number of carbon atoms in the alkyl groups of the reagents and with the reagent concentration when the alkyl groups are larger than butyl, but masking agents increase the extractability. An explanation proposed for this effect is the formation of polynuclear chelates. Diethyldithiophosphate can be used for the selective determination of cadmium, copper and lead in digested solid environmental samples. With 20 s sample loading at 8.7 ml min⁻¹, the enhancement factors are 35 for cadmium and copper or 26 for lead; the detection limits (3σ) are 0.8, 1.4 and 10.0 μg 1⁻¹ for cadmium, copper and lead, respectively.     

Dynamic ultrasound-assisted extraction of cadmium and lead from plants prior to electrothermal atomic absorption spectrometry

A dynamic ultrasound-assisted extraction step is proposed for the quantitative extraction of Cd and Pb from plant leaves prior to determination by electrothermal atomic absorption spectrometry (ETAAS). Beech leaves (a certified reference material—CRM 100—where the target analytes were not certified) were used for optimizing the extraction step by a multivariate approach. The samples (0.25 g) were subjected to dynamic ultrasound-assisted extraction with dilute nitric acid as extractant. The method was validated with a certified reference material BCR-062 (olive leaves) where both Cd and Pb are certified. The good agreement between the certified values and those found using the proposed method demonstrates its usefulness. The repeatability was 2.0 and 0.9% and the within-laboratory reproducibility was 7.1 and 2.8% for Cd and Pb, respectively. The precision of the method, together with its efficiency, rapidity, low cost and environmental acceptability makes it a good alternative for the determination of trace metals from plant material.     

Preconcentration of lead, cadmium and zinc on silica gel loaded with diethyldithiocarbamate prior to their determination by flame-atomic absorption spectrometry

A silica gel sorbent loaded with sodium diethyldithiocarbamate has been developed for the preconcentration of lead, cadmium and zinc prior to their determination by flameatomic absorption spectrometry (FAAS). The sorption and desorption of the metal ions was studied under both static and dynamic conditions. The metal ions were quantitatively retained on the silica gel sorbent based on an equilibrium time of less than 1 min. In case of the batch method, the effects of pH, shaking time, amount of sorbent, and desorption time were investigated. Among the desorption agents studied, only EDTA in ammonium chloride/ammonia buffer yielded quantitative recoveries. Freundlich's sorption isotherms determined for each metal show that sufficient sorption ability is obtained. The column method allows the preconcentration of metal ions from large sample volumes (e.g. 200 mL) using a flow rate of 5 mL min^–1. The influence of foreign ions present in natural waters and saline solutions was examined. The reproducibility of the total analytical method, expressed as relative standard deviation (RSD) is 1.8, 0.5 and 0.6%, for lead, cadmium and zinc, respectively.