Magnetic Solid-Phase Extraction Based on Modified Iron Oxide Nanoparticles for the Preconcentration of Ultra-Trace Amounts of Copper Ions in the Environmental and Plant Samples and its Determination Using FAAS

In the present work, magnetic iron oxide nanoparticles (MIONPs) coated with sodium dodecyl sulfate (SDS) and modified with 1-(2-pyridylazo)-2-naphthol (PAN) as a new nanoparticle were prepared and used as an adsorbent for the extraction and preconcentration of copper ions. After adsorption, copper ions were desorbed with nitric acid (HNO₃), followed by determination with flame atomic absorption spectrometry (FAAS). The extraction conditions0. were investigated systematically. The linear range 3.0–500.0 ng mL^?1 and the detection limit of 0.6 ng mL^?1 were obtained. The relative standard deviation (RSD) of the method for seven replicate determinations of 0.1 µg mL^?1 of Cu(II) was 2.2%. The method was applied for the determination of Cu(II) in different water samples with good trueness. The accuracy was also evaluated through analyses of a certified reference material (CRM TMDW-500).     

Determination of Available Cadmium and Lead in Soil by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

A cloud point extraction (CPE) procedure has been developed for the determination of available cadmium (Cd) and lead (Pb) in soil by flame atomic absorption spectrometry. The proposed method was based on the CPE of a complex from ammonium pyrrolidine dithiocarbamate (APDC) and metal Cd and Pb using emulsifier octyl polyethylene glycol phenol ether (OP) as surfactant. Conditions that would affect the complex formation and separation were researched in detail, including extraction conditions as well as pH, amount of the chelating agent, concentration of the surfactant, equilibration temperature and time, and salt effect. Under the optimized conditions, both of the calibration graphs were linear in range of 0–1.0 μg mL^?1 with detection limits of 0.29 ng mL^?1 for Cd and 2.10 ng mL^?1 for Pb. The relative standard deviation (RSD) for 11 replicate measurements at 0.10 μg mL^?1 of Cd and Pb were 2.18% and 4.04%, respectively. The enhancement factors were 48.8 and 61.6 for Cd and Pb, respectively. The recoveries of Cd and Pb at the spiking level of 0.10 μg g^?1 in soil samples were from 91.7% to 115% and from 91.0% to 115%, respectively. The proposed method has been applied to the determination of available Cd and Pb in soil.     

Determination of Trace Amounts of Cadmium Ions in Water and Plant Samples Using Ligand-Less Solid Phase Extraction-Based Modified Co3O4 Nanoparticles

In this study, a new Co₃O₄ nanoparticles (NPs) coated with sodium dodecyl sulphate (SDS) is developed for preconcentration of trace amounts of cadmium ions (Cd ²⁺) as a prior step to its determination by flame atomic absorption spectrometry (FAAS). The effects of various parameters, including pH of sample solution, amount of sorbent, flow rates of solution and eluent, sample volume, type, and least amount of the eluent for elution of the Cd ²⁺ from Co₃O₄ NPs were studied and optimized. Experimental conditions for effective separation of trace levels of the Cd ²⁺were optimized with respect to different experimental parameters in Column method. Under the best experimental conditions, the calibration curve was linear in the range of 1.0–500.0 ng.mL^?1 of cadmium (Cd) with R² = 0.999. The detection limit was 0.4ng.mL^?1 in the original solution (3S_b/m) and the relative standard deviation for eight replicate determination of 0.1µg.mL^?1 Cd was ±2.1%. The method was validated by the analysis of a certified reference material with the results being in agreement with those quoted by manufactures. The developed method was successfully applied to the extraction and determination of Cd in water and food samples with satisfactory results.     

Separation of Ag(I) Ions from Lepidium draba L. Plant and Water and Standard Samples by Carrier Element-Free Coprecipitation Method Prior to their Flame Atomic Absorption Spectrometric Determination

In this work, silver iodide (Ag(I)) ions were separated via the carrier element-free coprecipitation (CEFC) method using an organic coprecipitating agent, 1,6-diamino-4-(4-chlornphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile [DCODD] prior to its determination by ?ame atomic absorption spectrometry (FAAS). Analytical parameters including pH of aqueous solution, amount of DCODD, standing time, centrifugation rate and time, and sample volume were studied and optimized. Under the best experimental conditions, it was found that extraction can be performed from the sample volume of 500.0 for silver ion (preconcentration factor of 100.0). Linearity was maintained between 0.006 and 1.50 µg.mL^?1 for silver. Detection limit for silver based on 3Sb was 1.60 ng.mL^?1. The relative standard deviation of eight replicate measurements of 0.20 µg.mL^?1of silver was 2.10%. Finally, the developed method was successfully applied to extraction and determination of the silver ions in the Lepidium draba L plant, water and standard samples and satisfactory results were obtained.     

Effectiveness of the Iodide Ligand Along with two Surfactants on Desorbing Heavy Metals from Soils

Used with one of two surfactants (SDS, an anionic surfactant, and Triton X-100, a nonionic surfactant), the ligand, I^? was evaluated as a washing agent for the desorption of Cd from naturally and artificially contaminated soils. Increasing amounts of the ligand, I^?, with a surfactant, specifically removes higher levels of Cd but not Cu, Zn and Pb. After seven washings, the ligand, I^? with the nonionic surfactant, Triton X-100, removed 65 and 90% of the Cd from soils I and II, containing respectively, to 15 and 1275 mg of Cd/kg. The ligand, I^?, and the anionic surfactant, SDS, removed 35 and 70% of the Cd from soils I and II, respectively. Before washing, the carbonate fraction of soil I contained the most Cd (48%) while the exchangeable and carbonate fractions of soil II contained 29 and 33% of the total Cd, respectively. For soil I, SDS with/ without the ligand desorbed Cd mainly from the carbonate and oxide fractions, while only Triton X-100 with ligand I^? could remove Cd from the exchangeable fraction. For soil II, Cd was desorbed from the exchangeable fraction only when either surfactant was used in combination with the ligand. Thus, a surfactant with ligand can extract specific heavy metals from soils and selective sequential extraction is useful in identifying which fraction can be targeted by the surfactant – ligand agent.     

Determination of Water-Soluble and Acid-Soluble Zinc in Soils by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

A cloud point extraction (CPE) procedure has been developed for the determination of water-soluble and acid-soluble zinc (Zn) in soils by flame atomic absorption spectrometry. Deionized water and 0.1 mol L^–1 hydrochloric acid (HCl) were selected as extracting agents. In the proposed approach, 2-(5-bromo-2-pyridylazo)-5-diethylam-inophenol (5-Br-PADAP) was used as a chelating agent, and polyethylene glycol octyl phenyl ether (OP) was selected as the surfactant. Some factors including the pH of analytical solution, concentrations of the chelating agent and surfactant, equilibration temperature and time, and salt effect, which would affect the extraction efficiency and subsequent determination of Zn, were studied and optimized. Under the optimized conditions, the calibration graph was linear in the range of 5.0?×?10^–3 to 0.5 μg mL^–1, and preconcentration of 20 mL sample solution gave an enhancement factor of 25. The detection limit was 4.93?×?10^–3 μg mL^–1. Recoveries in the range of 95.0–110% were obtained. Some metal ions including iron (Fe²⁺), cobalt (Co²⁺), and manganese (Mn²⁺) would interfere with the determination of Zn. The interference from these ions can be eliminated using thiourea (0.5% w/v) and triethanolamine (0.5% w/v) as masking agents. The proposed method was applied to the determination of water-soluble and acid-soluble Zn in soils, which were collected from the suburbs of Zhengzhou, and satisfactory results were obtained. To have more understanding of the soils, we determined the total content of Zn in soils. The results showed that the water-soluble and acid-soluble Zn contents in different soils are not correlated with the total content. For example, the total content of Zn for the soil from a farm in north loop was very low, but the percentage of water-soluble Zn was very high.     

Graphite Furnace Atomic Absorption Spectrometry After Dispersive Liquid–Liquid Microextraction for the Determination of Selenium in the Anodic Slime

In the present study, a method based on dispersive liquid–liquid microextraction (DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) determination was proposed for the determination of selenium by using ammonium pyrrolidine dithiocarbamate (APDC) as the chelating reagent. The main factors influencing the DLLME were investigated systematically. Under the optimal conditions, the limit of detection for Se(IV) was 0.02 ng mL^?1. The relative standard deviation was 4.1% (C_Se(IV) = 0.2 ng mL^?1, n = 8) with an enhancement factor of 135.8-fold from only 5 mL of the water sample. The proposed method was successfully applied to the determination of Se(IV) in anodic slime and electrolyte samples. In order to validate the proposed method, a Certified Reference Material (trace elements in water, 1643e, NIST) was analyzed, and the determined value obtained was in good agreement with the certified value.     

Effects and relative toxicity of heavy metals on Cuscuta reflexa

The effects of four concentrations (0.5, 1, 5 and 10 μg mL^?1) of the heavy metals Hg, As, Pb, Cu, Cd, and Cr on some senescence variables of Cuscuta reflexa Roxb. were studied. All of the treatments, except 0.5 μg mL^?1, decreased Hill reaction activity, chlorophyll and protein contents and dry matter percentage in biomass and increased tissue permeability over control data. The harmful effects of the metals were best visible at 10 μg mL^?1. The general order of sensitivity was As > Cd > Pb > Hg > Cu > Cr (absolute metal concentration). The data suggest that Cuscuta reflexa shows tolerance to the heavy metals tested up to 0.5 μg mL^?1.     

Thermodynamics of Lead Sorption and Desorption in Soils

Thermodynamics of Lead (Pb) sorption and desorption was investigated with samples of a clayic Torrifluvent, a sandy clayic Calciorthid, and sandy Quartzipsamment. The values of activation energy for Pb sorption on the Calciorthid (ranged from 20.7 to 27.7 kJ mol^?1) were higher than those of the Torrifluvent (ranged from 3.4 to 17.4 kJ mol^?1) and the Quartzipsamment (1.5 to 4.6 kJ mol^?1). The energies of activation for adsorption “E_a” were greater than those for desorption “E_d”, indicating that more energy was needed to sorb Pb than to desorb Pb. The enthalpy of activation (ΔH^*) values indicate that Pb sorption is endothermic reaction while Pb desorption is exothermic reaction. The entropy of activation (ΔS^*) values for Pb sorption were negative and increased with increasing surface coverage. The free energy of activation (ΔG^*) values ranged from 81.2 to 89.2 and from 83.6 to 84.0 kJ mol^?1 for Pb sorption and desorption respectively.     

Studies of uptake and toxic effects of NI (II) on Salvinia natans

The uptake of Ni (II) and toxic effects of the metal on some biochemical parameters in Salvinia natans L. were studied. The uptake of Ni (II) by the plants gradually increased with increase in concentration of Ni (II) in the culture medium. Maximum accumulation of Ni (II) was noted within a day and maximum removal (about 90%) was recorded upto 20 Μg mL^?1 of Ni (II). Accumulation of the metal in roots (14.75 Μg mL^?1) is greater than that of shoots (5.25 Μg mL^?1). Ni (II)>10 Μg mL^?1 promoted senescence of Salvinia plants by decreasing chlorophylls, protein, amino acid, Hill activity, dry weight and by inducing necrosis. In the absence of other pollutants, Salvinia plants may be used for removal of Ni (II) from effluents and also as an indicator of Ni pollution.     

Surface Modification of Sporopollenin with Calixarene Derivative

In this study, p-tert-butylcalix[4]-aza-crown (CAC) immobilized sporopollenin (Sp) was used as a sorbent for the removal of Cu(II), Pb(II) and Zn(II) from aqueous media. Sporopollenin was firstly functionalized with 3-chloropropyltrimethoxysilane (CPTS) in order to obtain chloro-sporopollenin (Sp-Cl). The Sp-Cl was reacted subsequently with CAC yielding CAC-bonded sporopollenin (Sp-Cl-CAC). The new sorbent was characterized by infrared spectroscopy (FTIR), thermal analysis (TG/DTG) and scanning electron microscopy (SEM). The sorption properties of modified sorbent (Sp-Cl-CAC) are also investigated. The optimum pH values for the separation of metal ions from aqueous solution onto Sp-Cl-CAC were 5.0 for Pb(II) and Cu(II) and 5.5 for Zn(II). The maximum sorption capacities for Cu(II), Pb(II) and Zn(II) were 0.07 (4.44?mg?g^?1), 0.07 (4.58?mg?g^?1) and 0.14 (29.00?mg?g^?1) mmol?g^?1, respectively. Sorption thermodynamic parameters of such as free energy (?G ^o), enthalpy (?H ^o), and entropy (?S ^o) were evaluated.     

Influence of electrolytes on EDTA extraction of Pb from polluted soil

Because the economics of soil extraction processes depend on conservation and reuse of costly chelating agents, the ability of various electrolytes to modify EDTA extraction of Pb from a grossly-contaminated soil (Pb_T=21%) was investigated using batch equilibration experiments. In the absence of added electrolyte, a single 5-hr. extraction with 0.04 M EDTA (corresponding to 1∶1 Pb_T to EDTA ratio) released 65% of Pb_T over the pH 5 to 9 range. Under these conditions, Na⁺-, Li⁺-, and NH₄ClO₄ salts at 0.5 M increased Pb desorption to nearly 80%, probably from exchange displacement of soilbound Pb²⁺ and increased solubility of Pb-containing phases at higher ionic strength. Because Cl^? and ClO₄ ^? salts were equally effective, chlorocomplex formation was insignificant. Under slightly acidic conditions, Ca(ClO₄)₂ and Mg(ClO₄)₂ at 0.167 M caused roughly the same elevation in Pb recovery as 0.5M of the monovalent electrolytes. However, with progressively higher pH, Ca, and to a lesser extent Mg, suppressed Pb solubilization by competitive chelation of EDTA. Pb recovery by EDTA soil washing could be enhanced by addition of Ca salts at pH 4 to 6. Subsequent pH elevation in the presence of Ca would promote decomposition of Pb-EDTA complexes and separation of Pb as a hydroxide precipitate.     

Determination of lead in airborne particulate by hydride generation

The determination of low levels of Pb via hydride generation and measure by AAS is studied. It is found that the presence of an acidic medium (HCl 0.12M) and an oxidizing agent (4 mL of 7%) (M/V) H₂O₂ is necessary to generate PbH₄, independently of the oxidation state of Pb, and using as reducing agent a solution of NaBH₄ 7.5%. The role of the oxidizing agent is discussed. A method is proposed for the determination of Pb present on filters for sampling of the ambient atmosphere. A standard deviation of 0.0195 and RSD 2.45% a level of 1 μg mL^?1 of Pb was observed.     

Cadmium and lead in human body fluids,air and drinking water in the area of Cracow

The amount of Cd and Pb in full blood and in the urine of males in Cracow and in a control area were measured and compared to the background of the level of these metals in air, dust fall and drinking water. The investigations were carried out in the years 1984–85. The mean Cd level in body fluids of Cracow's inhabitants was significantly higher than in the control group, and it amounted to: 0.54 μg Cd 100 mL^?1 in blood and 2.13 μg Cd L^?1 in urine. The Pb content in blood of the Cracow group (15.74 μg 100 mL^?1) was also significantly higher than in the control one, while the Pb level in urine was similar in both populations, reaching values below 10 μg L^?1. The mean annual Cd concentration in air and the Cd content in the dust fall in Cracow were 3 times higher than in the control area. The mean annual Pb concentration in Cracow's air exceeded the permissible Polish norm. In comparison with the control area, the Pb concentration level in air and its content in the dust fall in Cracow were 5 and 2 times higher, respectively. The level of Cd and Pb concentration in drinking water in Cracow and in the control area were much lower than the permissible values; however, in Cracow they were somewhat higher than in the control area.     

Determination of Mn and Pb in atmospheric deposition at a remote coastal site

The electrothermal atomic absorption spectrophotometric determination of Mn and Pb in wet, dry and total deposition collected at American Samoa is hindered by interferences due to the dilute sea-spray matrix. Matrix modification procedures permit direct analysis below 1 ng ml^?1 for each trace metal. The median monthly deposition of Mn is 5.8, 5.0, and 10.0 ng cm^?2, and for Pb 9.5, 1.4, and 10.6 ng cm^?2 for wet, dry and total collections, respectively. Preliminary data suggest effective sampling using these methods at this remote site.     

Selective Determination of Chromium(VI) in Industrial Wastewater Samples by Micro-Electromembrane Extraction Combined with Electrothermal Atomic Absorption Spectrometry

This study describes application of free liquid membrane (FLM) in micro-electromembrane extraction (μ-EME) of Cr(VI) from wastewater samples. Amount of Cr(VI) was quantified by electrothermal atomic absorption spectrometry. The transportation of Cr(VI) across the FLM was explored by electrokinetic migration and ion-exchange process. FLM and acceptor solution types, pH of donor and acceptor solutions, applied electrical potential, as well as FLM thickness were optimized. Presence of an anion exchange carrier (methyl trialkyl-ammonium chloride, Aliquat 336) in FLM facilitated Cr(VI) transportation. The best performance was observed for 1-octanol (containing 5% Aliquat 336) with thickness of 1 mm used as FLM, under applied electrical potential of 75 V, when 0.5 M NaClO₄ and 0.1 M HCl were used as the acceptor and donor phases, respectively; and the extraction time was set to 5 min. Linearity was obtained in the working range of 0.5–14.0 ng mL^?1 Cr(VI) (R²?>?0.98). The calculated limit of detection was below 0.06 ng mL^?1. Application of this method to wastewater samples showed that relative recoveries of the spiked Cr(VI) in the samples were in the range of 73.8–85.1%, based on the standard addition method.     

A Sensitive Spectrophotometric Method for Determination of Trace Quantities of Indium in Soil

A simple and very sensitive method determining microgram quantities of indium in soil has been developed. The spectrophotometric method (??=?1.74?×?10⁵ l mol^-1 cm^-1) based on the mixed complex In (III) with Chrome Azurol S and benzyldodecyldimethylammonium bromide was used for the analysis. A preliminary separation is made by extracting indium into butyl acetate from 5 M HBr solution. The selectivity of indium extraction and determination in the presence of macro- and micro components of soil was studied. Prior reduction of Fe (III) to Fe (II) with ascorbic acid prevents its co-extraction with indium. Indium was determined in synthetic mixtures corresponding to soil compositions and real samples of soil from different agricultural and industrial regions of Poland. The content of indium was found from the calibration graph (in the range, 0.12–0.48 μg/ml; r?=?0.9991) obtained after extraction. The precision was satisfactory: % RSD (n?=?6) ranged from 2.7 to 8.2. The average indium standard recovery ranged from 95 to 101%. Analysis using an ICP-OES method gave comparable results.     

Cadmium accumulation and bioavailability in Coontail (Ceratophyllum demersum L.) plants

The aquatic vascular plant (Ceratophyllum demersum L.) was investigated as a potential biological filter for removal of Cd from wastewaters. Plants were grown in and harvested weekly from 0.10 M Hoagland nutrient solutions containing concentrations of Cd from 0.01 to 1.03 μg Cd mL^?1. Tissue Cd was positively correlated to increased concentrations of Cd in solution. Concentration factors (CFs) of Cd in plants after one week were 13.3 for the 0.01 μg Cd mL^?1 treatment; 451.4 for plants treated with 0.04 μg Cd mL^?1, and 506.5 for plants treated with 1.03 μg Cd mL^?1. Plants treated with 0.01 μg Cd mL^?1 sustained tissue Cd concentrations almost 9-fold over those at week 1. However, after 5 weeks tissue Cd concentration in plants exposed to 1.03 μg Cd mL^?1 had decreased 97% compared to the week 1 concentration. Growth measurements of dry weight, stem lengths, and lateral shoot growth were nagatively correlated to increased Cd treatments. Our results suggest that Coontail exposed to very low Cd concentrations (0.01 μg Cd mL^?1) can take up and accumulate Cd. However, plants exposed to Cd at 0.04 μg Cd mL^?1 or above did not accumulate Cd past one week.     

Thirteen-year survival study of an environmentalEscherichia coli in field mini-plots

A multiple-antibiotic resistantE. coli was applied to rye-grass covered field mini-plots to simulate point-source contamination. Using three mini-plots for testing and a fourth as a control, the ability of the tracer bacterium to survive under field conditions was studied. Three test plots each received separately 10⁷, 10⁸, or 10¹⁰ cfu mL^?1 E. coli grown for 24 h. in 5 L one-third strength Tryptic soy broth. In Phase I of the study, it was determined that the tracer disappeared from leaf surfaces of rye-grass covering the plots after 41 days. In Phase II, determination of the presence of the tracer in the top 2″ (5 cm) of soil after two months elapsed time indicated that tracer cfu/g dry wt. of soil had declined five, three, and three-logs for test plots 1,2, and 3. In Phase III, subsurface soil sampling using a soil auger on the three test minei-plots indicated the tracer had penetrated through the top-soil and into the underlying B horizon (20 to 50 cm down). In Phase IV, detailed sampling by excavation of the subsurface soil Horizons of the third test mini-plot showed that the tracer had also penetrated through the hardpan (C Horizon) located 0.6 m below the surface to enter the groundwater (1.06 m deep) (Phase V).E. coli counts fell precipitously to 10³ cfu g^?1 in soil and then, in the groundwater at the groundwater-soil interface, persisted at a concentration of 10³ cfu 100 mL^?1 for 2 yr. As time past, tracer counts fell to 145 cfu/100 mL in 6 yr. rose to 820 cfu 100 mL^?1 in 1986 (8 yr elapsed time), and then fell to 25 cfu 100 mL^?1 in 1991 after 13 yr. Serotyping of 1986E. coli isolates indicated that 62% were of the original tracer serotype (0.128:B12) while only 43% of the 1991 isolates were of the same serotype. The penetration rate of the tracer down through the mini-plot soil into the groundwater was 0.02 m day^?1 while downslope dispersion occurred at an estimated rate of 1.0 m day^?1. The implications of the above findings are discussed.     

Plant Growth-Promoting Rhizobacteria (PGPR) and Phosphorus Fertilizer-Assisted Phytoextraction of Toxic Heavy Metals from Contaminated Soils

Phytoremediation is a remediation technique that involves the use of plants to extract, sequester, and/or detoxify pollutants through physical, chemical, and biological processes. The use of phytoremediation is expanding due to its cost-effectiveness compared with conventional methods. This study was conducted to investigate the effects of autumn and spring application of plant growth-promoting rhizobacteria (PGPR, 10⁸ cfu mL^?1 Bacillus megaterium var. phosphaticum sprayed at 250 mL plot^?1) and phosphorus (P) fertilizer (0, 11, 22, 33, 44 kg P ha^?1) on dry matter yield and heavy metal uptake by plants in soils contaminated with heavy metals. Field experiments were conducted using a randomized complete block design with four replications between 2004 and 2007. The results of the study indicated that P fertilization, but not PGPR application, significantly affected dry matter yield. Application of PGPR increased heavy metal availability in soils and the heavy metal uptake of meadow plants. The heavy metal content of the meadow plants resulting from PGPR application was 4–6 times higher for the spring application than the autumn application. Approximately 16, 30, 10, 10, and 3 growing seasons without PGPR are necessary to remove all lead (Pb), nickel (Ni), boron (B), manganese (Mn), and zinc (Zn), respectively, from polluted soil. The time required for Pb, Ni, B, Mn, and Zn removal could be further decreased to approximately 4, 6, 3, 3, and 1 growing seasons, respectively, with 33 kg phosphorus pentoxide (P₂O₅) ha^?1 and 10⁸ cfu mL^?1 PGPR applications at rates of 250 mL plot^?1 in the spring season.