Distribution of metal(loid)s in particle size fraction in urban soil and street dust: influence of population density.

Assessment of street dust is an invaluable approach for monitoring atmospheric pollution. Little information is available on the size distribution of contaminants in street dusts and urban soils, and it is not known how the population density would influence them. This research was carried out to assess the size distribution of trace metal(loid)s in street dust and urban soil, and to understand how population density might influence the size-resolved concentration of metal(loid)s. Three urban areas with a high, medium and low population density and a natural area were selected and urban soil and street dust sampled. They were fractionated into 8 size fractions: 2000-850, 850-180, 180-106, 106-50, 50-20, 20-10, 10-2, and < 2 µm. The concentration of Pb, Zn, Cu, Cd, Cr, Ni, As, and Fe was determined, and enrichment factor and grain size fraction loadings were computed. The results indicated that the concentration of Pb, Zn, Cu, Cd, and Cr was highly size dependent, particularly for particles < 100 µm, especially for street dust. Low concentrations of Ni and As in street dust and urban soil were size and population density independent. Higher size dependency of the metals concentration and the higher degree of elemental enrichment in the street dust fractions than the urban soils indicate higher contribution of human-induced pollution to the dust. Findings also confirm the inevitability of size fractionation when soils or dusts are environmentally assessed, particularly in moderately to highly polluted areas. Otherwise, higher concentrations of certain pollutants in fine-sized particles might be overlooked leading to inappropriate decisions for environmental remediation.

Phytoremediation of mine tailings with Atriplex halimus and organic/inorganic amendments: A five-year field case study.

Mine tailings have adverse chemical and physical conditions, including high concentrations of metals and salts, low organic matter content, and unbalanced rates of nutrients which limit the development of vegetation. A large scale field experiment was conducted to reclaim a tailing pond by triggering the growth of native species by spontaneous colonization by tilling (TL) the tailing pond surface and using marble waste (CaCO3; MW), pig slurry (PS) and their combination (MW + PS) as soil amendments. Soil physicochemical properties and water and DTPA extractable metal concentrations of bulk and rhizosphere soils were analyzed after five year from the application of the treatments. In addition, plants of Atriplex halimus from each treatment were collected and metals in roots, leaves and stems analyzed. Before amendments application, the studied pond showed a neutral pH, high salinity and a moderate organic carbon content. After five years, the pH value was significantly increased only in MW plot. The results showed significant increases of DTPA-extractable Zn in MW and MW + PS plots, Pb in all treatments except MW plot, Cd only in PS plot, and Cu only in MW + PS plot. A. halimus was the most dominant species, growing spontaneously in all plots, with lower vegetation cover in CT and MW plots, 6% and 2% respectively. Application of MW increased leaf Pb accumulation by 2.5-fold and Cd by 55%, when compared to the CT. The high initial salinity and probable substitution of metals by Ca2+ on exchangeable surfaces of soil particles may be the reasons for higher uptake of metals in MW plot when compared to the other plots. Although this plant is widely utilized in contaminated sites for phytostabilization purposes, it may absorb and translocate high concentrations of metals to the aboveground tissues in saline contaminated sites.

Construction of a new selective coated disk electrode for Ag (I) based on modified polypyrrole-carbon nanotubes composite with new lariat ether.

A poly (vinyl chloride) (PVC) matrix membrane ion-selective electrode for silver (I) ion is fabricated based on modified polypyrrole - multiwalled carbon nanotubes composite with new lariat ether. This sensor has a Nernstian slope of 59.4±0.5mV/decade over a wide linear concentration range of 1.0×10(-7) to 1.0×10(-1)molL(-1) for silver (I) ion. It has a short response time of about 8.0s and can be used for at least 50days. The detection limit is 9.3×10(-8)molL(-1) for silver (I) ion, and the electrode was applicable in the wide pH range of 1.6 -7.7. The electrode shows good selectivity for silver ion against many cations such as Hg (II), which usually imposes serious interference in the determination of silver ion concentration. The use of multiwalled carbon nanotubes (MWCNTs) in a polymer matrix improves the linear range and sensitivity of the electrode. In addition by coating the solid contact with a layer of the polypyrrole (Ppy) before coating the membrane on it, not only did it reduce the drift in potential, but a shorter response time was also resulted. The proposed electrode was used as an indicator electrode for potentiometric titration of silver ions with chloride anions and in the titration of mixed halides. This electrode was successfully applied for the determination of silver ions in silver sulphadiazine as a burning cream.

Antibiotic-coated pins for prevention of pin-tract infection: a rabbit study.

PURPOSE. To evaluate the efficacy of antibiotic-coated pins for prevention of pin tract infection in a rabbit model. METHODS. 10 rabbits were divided into 2 groups. A unilateral external fixator was applied to the tibia with 4 self-taping 1.8-mm pins. In the test group, pins were coated with hydroxyapatite and antibiotic. In the control group, pins were not coated. All pins were then placed in Staphylococcus aureus- containing media. At postoperative day 5, all 40 pin sites were subcutaneously inoculated with S aureus. The sites were clinically examined for signs of pin tract infection. Nine days later, a piece of soft tissue around the pin site was harvested for microbiologic examination. RESULTS. In the test group, all except one pin sites appeared clean and without clinical infection, and the culture media remained clear. In the control group, all pin sites showed evidence of clinical infection and yielded positive cultures, and the culture media became dark indicating growth of S aureus. CONCLUSION. Antibiotic-coated pins were effective in preventing pin tract infection.

Uptake of phosphorus and lead by Brassica juncea and Medicago sativa from chloropyromorphite.

In situ remediation of lead (Pb)-contaminated soils via phosphate amendments has been extensively used to immobilize Pb as pyromorphite. However, in phosphorus (P) deficient soils, plants may develop extensive root systems to access P in any P-containing minerals, thereby affecting the stability of Pb5 (PO4)3Cl (Chloropyromorphite; CP). We grew Brassica juncea and Medicago sativa in sand culture to evaluate the stability of CP in the presence or absence of hydroxyapatite (HA) as P source. Treatments (per kilogram of sand) watered with P-nutrient solution were control [PC0, (without CP)], 1, and 5 g Pb as CP [PC1, and PC5] and 0.45 g P as HA (PA), and those of watered with P-free nutrient solution were 1 and 5 g Pb as CP [NC1 and NC5], 5 g Pb as CP plus 0.45 g P as HA [NAC5], and 0.45 g P as HA [NA]. Plants in NC1 and NC5 treatments showed stunted growth and reductions in shoot elongation and leaf size. Among CP treated pots, the highest shoot Pb uptake was observed in NAC5 treatment. The results suggested that Pb accumulation and translocation in the plants was markedly higher in P-sufficient conditions than in P-deficient conditions.

Rat xenograft chondrosarcoma development by human tissue fragment.

UNLABELLED: Chondrosarcoma is one of the most difficult types of cancers to diagnose and treatment. Therefore, the development of a reliable animal model for chondrosarcoma would be a helpful tool to study of the tumor's growth and progression. AIM: We conducted this study to develop a chondrosarcoma on rat by graft of human chondrosarcoma tumor tissue. METHODS: Fourteen male Sprague-Dawley rats equally divided in xenograft-implanted and control groups. On the lateral side of the right femur distal 1/3, 5 mm incision was done on the skin after animal anesthesia. Then, was drilled 3 mm on the bone and implanted the xenograft in the bone. Radiography was taken from the operated femur weekly until the fourth week and monthly for 3 months. Four animals of each group were sacrificed after 4 weeks of operation; femur was harvested for histopathological study. RESULTS: Radiological images showed sclerotic area on the implanted bone after 4 weeks of operation. Sections from tumoral areas reveal cartilage forming hypercellular neoplastic tissue with lobular pattern of growth and foci of adjacent tissue invasion such as bone trabeculas and bone marrow. CONCLUSION: the present study showed that rat xenograft chondrosarcoma can develop by human chondrosarcoma fresh tissue fragments.

Construction of a new Cu2+ coated wire ion selective electrode based on 2-((2-(2-(2-(2-hydroxy-5-methoxybenzylidene amino)phenyl)disufanyl)phenylimino)methyl)-4-methoxyphenol Schiff base.

In this article a new coated platinum Cu(2+) ion selective electrode based on 2-((2-(2-(2-(2-hydroxy-5-methoxybenzylideneamino)phenyl)disufanyl)phenylimino) methyl)-4-methoxyphenol Schiff base (L(1)) as a new ionophore is described. This sensor has a wide linear range of concentration (1.2 × 10(-7)-1.0 × 10(-1) mol L(-1)) and a low detection limit of 9.8 × 10(-8) mol L(-1)of Cu(NO(3))(2). It has a Nernstian response with slope of 29.54 ± 1.62 mV decade(-1) and it is applicable in the pH range of 4.0-6.0 without any divergence in potential. The coated electrode has a short response time of approximately 9s and is stable at least for 3.5 months. The electrode shows a good selectivity for Cu(2+) ion toward a wide variety of metal ions. The proposed sensor was successfully applied for the determination of Cu(2+) ion in different real and environmental samples and as indicator electrode for potentiometric titration of Cu(2+) ion with EDTA.

Carbon nanotube composite coated platinum electrode for detection of Ga(III).

This study demonstrates the application of composite multi-walled carbon nanotube (MWCNT) polyvinylchloride (MWNT-PVC) based on 7-(2-hydroxy-5-methoxybenzyl)-5,6,7,8,9,10-hexahydro-2H benzo [b][1,4,7,10,13] dioxa triaza cyclopentadecine-3,11(4H,12H)-dione ionophore for gallium sensor. The sensor shows a good Nernstian slope of 19.68 ± 0.40 mV/decade in a wide linear range concentration of 7.9 × 10(-7) to 3.2 × 10(-2)M of Ga(NO(3))(3). The detection limit of this electrode is 5.2 × 10(-7)M of Ga(NO(3))(3). This proposed sensor is applicable in a pH range of 2.7-5.0. It has a short response time of about 10s and has a good selectivity over nineteen various metal ions. The practical analytical utility of this electrode is demonstrated by measurement of Ga(III) in river water.

Carbon composite-PVC based membrane coated platinum electrode for chromium determination.

A new synthesized 1-(2-(1H-imidazole-1-yl)-1-(4-methoxyphenyl)ethylidene)-2-phenyl hydrazine has been used as an ionophore in carbon composite-PVC coated platinum electrode for fabrication of chromium(III)-selective sensor. The homogenization procedure of membrane mixture was performed by applying of the ultrasound in this respect. The sensor shows a good Nernstian slope of 19.62 ± 0.45 mV decade(-1) in a wide linear range concentration of 8.4 × 10(-8)-1.0 × 10(-2)M and a detection limit of 6.8 × 10(-8)M for Cr(NO(3))(3). The proposed electrode has a short response time of about 10s and is reproducible and stable for a period of at least 2 months. The performance of the sensor is pH independent in the pH range of 3.3-5.9 and it also works well in partially non-aqueous medium. The electrode has good selectivity relative to variety of metal ions. The practical analytical utility of the electrode is demonstrated by measurement of Cr(III) quantitatively in multivitamin, mineral water and also as an indicator electrode in the potentiometric titration of chromium (III) against EDTA.

A selective and sensitive carbon composite coated platinum electrode for aluminium determination in pharmaceutical and mineral water samples.

A novel coated wire electrode (CWE) for Al(III) ions is described based on 2-(1H-benzo[d]imidazole-1-yl)-1-phenylethanoneoxime as a new ionophore in carbon-PVC composite. The sensor exhibits significantly enhanced selectivity toward Al(3+) ions over the concentration range 4.3 x 10(-7) to 5.0 x 10(-2)M with a lower detection limit of 2.5 x 10(-7) M and a Nernstian slope of 19.41+/-0.52 mV decade(-1) of aluminium activity. This sensor has a short response time of about 10s and is reproducible and stable for at least forty-five days. This proposed CWE which is designed for the first time revealed good selectivity for Al(III) over a wide variety of other cations. The performance of the sensor is best in the pH range of 3.1-5.5 and it also works well in partially non-aqueous medium. Moreover, the assembly has been successfully used as an indicator electrode in the potentiometric titration of aluminium (III) against EDTA and also in determining Al(III) quantitatively in pharmaceutical and mineral water samples.

A highly selective and sensitive disposable carbon composite PVC-based membrane for determination of lead ion in environmental samples.

A Pt wire coated with phenyl hydrazone derivative-carbon composite in a poly(vinyl chloride) membrane was used for detection of lead. The sensor had a Nernstian slope of 29.46+/-0.41 mV/decade over a wide linear concentration range of 7.7 x 10(-7) to 1.0 x 10(-1) mol L(-1) for Pb(NO(3))(2). The detection limit was 3.2 x 10(-7) mol L(-1) and the electrode was applicable in the pH range of 3.7-6.3. It had a short response time of approximately 6s and was used at least for 70 days. The electrode has exhibited good selectivity for Pb(II) relative to 19 other metal ions. The functionality of the proposed sensor was also investigated in binary water-alcohol mixture and it concluded that 23% water-methanol and 20% water-ethanol content could not bring out any changes in its potential. The practical analytical utility of the electrode was demonstrated by measurement of Pb(II) in mineral rock and potentiometric titration of sulfate anion.

Application of spectral beta-correction method and partial least squares for simultaneous determination of V(IV) and V(V) in surfactant media.

Simultaneous determination of V(IV) and V(V) was performed by application of partial least squares when the calibration matrix was obtained using beta-correction spectra. Two reaction between V(IV) and V(V) and Pyrogallol Red as a ligand in presence of cethyltrimethylammoniumbromide (CTAB) media has been investigated and applied to the simultaneous spectrophotometric determination of these species. The parameters controlling behavior of the system were investigated and optimum conditions selected. Determinations were made over the concentration range 0.6-4.50 microg ml-1 of V(IV) and 0.3-5.50 microg ml-1 of V(V). Applying this method to simultaneous determination of these metal ions in several real samples with total relative standard error less than 5% validated the proposed method.

Application of principle component analysis-artificial neural network for simultaneous determination of zirconium and hafnium in real samples.

Determination of zirconium and hafnium were done by applying singular value decomposition and a feed forward Neural Network Algorithm with back propagation of error. The determination of trace amounts of mixtures of Zr(IV) and Hf(IV) in various matrices (river, tap and industrial wastewater) were investigated by PC-ANN using the complexes formed between Alizarin Red S, Zr and Hf. The results showed that measurement is possible in the ranges of 0.03-3.4 and 0.2-7.0 microg ml-1 for Zr(IV) and Hf(IV), respectively. The detection limits were 0.02 and 0.08 microg ml-1 for Zr(IV) and Hf(IV), respectively. The results also show very good agreement between true and predicted concentration values and have the ability to use in routine analysis.

Simultaneous determination of phenytoin, barbital and caffeine in pharmaceuticals by absorption (zero-order) UV spectra and first-order derivative spectra--multivariate calibration methods.

The quantitative predictive abilities of partial least squares (PLS-1) and principle component regression (PCR) on absorption (zero-order) UV spectra are compared with the results obtained by the use of these multivariate calibration methods on first-order derivative spectra. Both approaches were satisfactorily applied to the simultaneous determination of these drugs in synthetic and pharmaceutical mixtures. Significant advantages were found in the simultaneous determination of phenytoin, barbital and caffeine in binary and ternary mixtures, by application of different multivariate calibration methods when the calibration matrix was performed using the first-order derivative spectra. The proposed method was validated by applying it to the analysis of binary and ternary mixtures of phenytoin, barbital and caffeine. Determinations were made over the concentration ranges of 0.24-22.0, 0.01-27.0 and 0.049-27.0 microg ml(-1) for phenytoin, barbital and caffeine, respectively, in the binary and 0.45-22.0, 0.05-26.0 and 0.05-20.0 microg ml(-1) for phenytoin, barbital and caffeine, respectively, in the ternary mixtures. The relative standard errors in the determinations were less than 3% in most cases.

Simultaneous determination of antimony and bismuth by beta-correction spectrophotometry and an artificial neural network algorithm.

Simultaneous determinations of antimony and bismuth were done by beta-correction spectrophotometry and a feed forward neural network algorithm with back propagation of error. The sensitivity was improved using beta-correction spectrophotometry. The determination of trace amounts of mixtures of Sb and Bi in various matrices (river, tap and industrial wastewater) were investigated by neural network and beta-correction spectrophotometry using the complexes formed between pyrogallol red, Sb and Bi. The results showed that measurement is possible in the ranges of 0.05-5.0 and 0.2-3.2mugml(-1) for Sb(III) and Bi(III), respectively. The results also show very good agreement between true and predicted concentration values and have the ability to use in routine analysis.

A selective modified carbon paste electrode for determination of cyanide using tetra-3,4-pyridinoporphyrazinatocobalt(II).

A chemically modified carbon paste electrode with 3,4-tetra pyridinoporphirazinatocobalt(II) (Co(3,4 tppa) was applied to the determination of free cyanide ion. The electrode has a linear range between 1.5x10(-5)M and 1.0x10(-2)M with a Nernstian slope of 60+/-1.5mV/decade and its detection limit is 9x10(-6)M. The response time of electrode is 5min. The proposed electrode was applied successfully for the determination of cyanide in commercially available spring water. Some anions, such as SCN(-), I(-), Cl(-), Br(-) and oxalate that are usually serious interfering species for most of cyanide selective electrodes, did not have any interfering effect for this proposed electrode.

Application of the spectral correction method and "neural networks" for simultaneous determination of V(V) and Al(III).

Simultaneous determination of V(V) and Al(III) was performed by application of neural networks when the calibration matrix was performed using beta-correction spectra. Two reactions between V(V) and Al(III) and Alizarin Red S (ARS) as a ligand have been investigated and applied for the simultaneous spectrophotometric determination of these metal ions. The parameters controlling behavior of the system were investigated and optimum conditions selected. Feed-forward neural networks have been trained to quantify considered metal ions in mixtures under optimum conditions. Sigmoidal functions were used in the hidden and output layers. Determinations were made over the concentration range 0.10-7.80mugml(-1) of V(V) and 0.11-4.20mugml(-1) of Al(III). Applying this method satisfactorily to simultaneous determination of these metal ions in several synthetic solutions with total relative standard error less than 4.02% validated the proposed method.

Determination of l-histidine by modified carbon paste electrode using tetra-3,4-pyridinoporphirazinatocopper(II).

This paper describes a potentiometric method for determination of l-histidine (l-his) in aqueous media, using a carbon paste electrode modified with tetra-3,4-pyridinoporphirazinatocopper(II) (Cu (3,4tppa)). The electrode exhibits linear response to the logarithm of the concentration of l-histidine from 2.4 x 10(-5) to 1.0 x 10(-2)M, with a response slope of -49.5 +/- 1mV and response time of about 1.5min. The detection limit according to IUPAC recommendation was 2.0 x 10(-5)M. The proposed electrode shows a good selectivity for l-his over a wide variety of anions. This chemically modified carbon paste electrode was successfully used for the determination of l-his in a synthetic serum and RANDOX control serum solutions.

Simultaneous determination of Sb(III) and Sb(V) by partial least squares regression.

A method for simultaneous spectrophotometric determination of Sb(III) and Sb(V) using multivariate calibration method is proposed. This method is based on the development of the reaction between the analytes and pyrogallol red at pH 2.00. The selection of variables was studied. A series of synthetic solutions containing different concentrations of Sb(III) and Sb(V) were used to check the prediction ability of the partial least squares model. The calibration curves were linear over the range of 0.3-3.4 and 0.3-3.0 microg ml(-1) for Sb(III) and Sb(V), respectively. The detection limits were 0.177 and 0.200 microg ml(-1) for Sb(III) and Sb(V), respectively.

Chemically modified carbon paste electrode for determination of copper(II) by potentiometric method.

The utility of carbon paste electrode modified with DTPT (3,4-dihydro-4,4,6-trimethyl-2(1H)-pyrimidine thione) for the potentiometric determination of Cu(II) in aqueous medium is demonstrated. The electrode exhibits linear response to Cu(II) over a wide concentration range (9.77x10(-7)-7.6x10(-2)) with Nernstian slope of 30+/-2 mV per decade. It has a response time of about 45 s and can be used for a period of two months with good reproducibility. The detection limit of this electrode was 7.0x10(-7) M. The proposed electrode shows a very good selectivity for Cu(II) over a wide variety of metal ions. This chemically modified carbon paste electrode was successfully used for the determination of Cu(II) in electronics waste sample solution.