scholarly journals Evaluation of the P-solubilizing activity of soil microorganisms and its sensitivity to soluble phosphate

2011 ◽  
Vol 48 (No. 9) ◽  
pp. 397-400 ◽  
Author(s):  
O. Mikanová ◽  
J. Nováková
Keyword(s):  
Tricalcium Phosphate ◽  
Agricultural Soils ◽  
Potassium Phosphate ◽  
Direct Determination ◽  
Soluble Phosphate ◽  
Natural Ecosystems ◽  
High Concentrations ◽  
Filter Papers ◽  
Solubilizing Activity

Microbial solubilization of hardly soluble mineral phosphates in soil is an important process in natural ecosystems and in agricultural soils. Regulation of the P-solubilizing activity by the presence of soluble phosphates in medium was determined. For this reason we decided to test a&nbsp;number of soil bacteria showing a&nbsp;high P-solubilizing activity for its sensitivity to the presence of soluble dihydrogen potassium phosphate in medium. At these studies, the direct determination of the solubilized phosphate in medium was masked by the presence of relatively high concentrations of soluble phosphate added. Therefore, we have modified the method, determining the residual tricalcium phosphate. The effect of soluble phosphate in medium on the P-solubilizing activity of rhizosphere isolates and strains of Rhizobium were tested in liquid cultures with the addition of various concentrations of soluble KH<sub>2</sub>PO<sub>4</sub>. The medium was filtered after incubation and the remaining tricalcium phosphate was separated by filtration. Filter papers with the remaining tricalcium phosphate were hydrolysed with 2N H2SO4. Phosphorus was determined spectrophotometrically. The P-solubilizing activity was expressed as a&nbsp;difference between the tricalcium phosphate added and its remainder after the incubation. These results fully confirmed that there exist the strains, whose P-solubilizing activity is inhibited and other strains, whose P-solubilizing activity is not inhibited or is inhibited very little in the presence of soluble phosphate. The use of our adapted method was much more suitable for this type of experiments.

scholarly journals Residues of Persistent Organic Pollutants (POPs) in Agricultural Soils Adjacent to Historical Sources of Their Storage and Distribution—The Case Study of Azerbaijan

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1815 ◽  
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Karolina Lewińska ◽  
Elton Mammadov ◽  
Anna Karczewska ◽  
Bożena Smreczak ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Environmental Protection Agency ◽  
Agricultural Soils ◽  
The United States ◽  
Natural Soil ◽  
Polycyclic Aromatic ◽  
High Concentrations ◽  
Total Concentrations

The aim of this study was to identify and examine the levels of organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in soil collected from the surroundings of historical pesticide storage facilities on former agricultural aerodromes, warehouses, and pesticide distribution sites located in the most important agricultural regions in Azerbaijan. The conducted research included determination of three groups of POPs (occurring together), in the natural soil environment influenced for many years by abiotic and biotic factors that could have caused their transformations or decomposition. In this study, soil samples were collected in 21 georeferenced points located in the administrative area of Bilasuvar, Saatly, Sabirabad, Salyan and Jalilabad districts of Azerbaijan. Soil chemical analysis involved determination of organochlorine compounds (OCP): hexachlorocyclohexanes (HCHs) (three isomers α-HCH, β-HCH and γ-HCH) and dichlorodiphenyltrichloroethanes (DDTs) (six congeners 2,4′DDT; 4,4′DDT; 2,4′DDE; 4,4′DDE; 2,4′DDE; and 4,4′DDE); polycyclic aromatic hydrocarbons (PAHs): 16 compounds from the United States Environmental Protection Agency US EPA list and, PCBs (seven congeners identified with the following IUPAC numbers: 28, 52, 101, 118, 138, 153, and 180). Our research showed that OCPs reached the highest concentration in the studied areas. The total concentrations of OCPs ranged from 0.01 to 21,888 mg∙kg−1 with significantly higher concentrations of Σ6DDTs (0.01 μg kg−1 to 21880 mg kg−1) compared to ΣHCH (0.14 ng kg−1 to 166.72 µg kg−1). The total concentrations of PCBs in the studied soils was varied from 0.02 to 147.30 μg·kg−1 but only PCB138 and PCB180 were detected in all analyzed samples. The concentrations of Σ16 PAHs were also strongly diversified throughout the sampling areas and ranged from 0.15 to 16,026 mg kg−1. The obtained results confirmed that the agricultural soils of Azerbaijan contained much lower (up to by three orders of magnitude) concentrations of PCBs and PAHs than DDT. It is supported by the fact that PCBs and PAHs were not directly used by agriculture sector and their content results from secondary sources, such as combustion and various industrial processes. Moreover, the high concentrations of PAHs in studied soils were associated with their location in direct neighborhood of the airport, as well as with accumulation of contaminants from dispersed sources and long range transport. The high concentrations of pesticides confirm that deposition of parent OCPs have occurred from obsolete pesticide landfills.

Inorganic polysulfides’ quantitation by methyl iodide derivatization: dimethylpolysulfide formation potential

2004 ◽  
Vol 49 (9) ◽  
pp. 179-184 ◽  
Author(s):  
A. Goifman ◽  
D. Ryzkov ◽  
J. Gun ◽  
A. Kamyshny ◽  
A.D. Modestov ◽  
...  
Keyword(s):  
Methyl Iodide ◽  
Direct Determination ◽  
Solubility Limit ◽  
Environmental Significance ◽  
Valuable Alternative ◽  
Natural Systems ◽  
Low Concentrations ◽  
Inorganic Polysulfides ◽  
High Concentrations

Inorganic polysulfides are important intermediates in the formation of dimethylpolysulfides and possibly other volatile sulfur compounds of environmental significance. Currently, direct determination of these ions in the concentration range of natural systems is practically impossible, particularly under oxic conditions. Polysulfide quantification by derivatization with methyl iodide or d6-methyl iodide is emerging as a valuable alternative method for studies of polysulfide formation in natural systems. This manuscript presents detailed studies aimed at the evaluation of this method. We determined the conversion of the inorganic polysulfides to dimethylpolysulfides by methylation with methyl iodide. Close to 100 per cent of the molar concentration of polysulfide salts were converted to organic polysulfides for very low concentrations of dissolved polysulfide solutions, but only a small recovery was obtained for high concentrations of polysulfide precursors or when the solubility limit was exceeded. The recovery of polysulfides based on the calculated dissolved polysulfide concentration exceeds 1,000 per cent for very low dissolved concentrations of polysulfides. This unexpected dependence is attributed to continuous inorganic polysulfide formation from hydrogen sulfide and sulfur precipitate concurrent with, and in fact driven by, the methylation process.

scholarly journals Trace Determination of Selected Heavy Metal Ions in Bleaching Creams in the Local Market of Saudi Arabia

2017 ◽  
Vol 14 (4) ◽  
pp. 1349-1354
Author(s):  
Faten M. Ali Zainy
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Saudi Arabia ◽  
Direct Determination ◽  
Optical Emission ◽  
Local Market ◽  
Icp Oes ◽  
Recovery Percentage ◽  
High Concentrations

ABSTRACT: Bleaching cream and cosmetics products of skin have risk of toxicity and deleterious effects to the human health because of their multiplicative contamination with heavy metals and uncertain mixing of different components. Thus, the present study reports a comprehensive study on the trace selected heavy metal (Hg, Cd, Ti, Bi, Pb, As and Tl) determination in 16 samples of bleaching creams and samples mixture of bleaching creams simultaneously to get a double activity (shiny and faster) on the skin from the local market of Saudi Arabia. Samples were digested with high pressure microwave technique followed by direct determination by inductive coupled plasma - optical emission spectrometer (ICP-OES). Hg, Bi, Ti and Pb levels on samples were found equal 5739.16, 7013.53, 21407.73, 456.70 µg/g, respectively whereas other elements (Cd, As and Tl) were found less than 28.99 ppm. One sample of the mixtures showed high concentrations of Hg (13338.50 µg/g,) and Bi (619.23 µg/g). Thus, creams and cream mixtures containing heavy metals above the permissible limit must be blind. The lower detection limits (LOD) were achieved at 2.5-50 µg/g concentration level, RSD was less than 14.72%, and recovery percentage for cosmetics were in the range of 88.52 -99.62%. The proposed method for sample digestion and ICP-OES measurements was fast, precise, convenient and provided good recovery of the tested elements.

scholarly journals The determination of the stability of nitrogen-fixing microorganisms of the soil of Ecuador to toxic metals CrO42–, Ni2+, Cu2+

2018 ◽  
Vol 23 ◽  
pp. 267-272
Author(s):  
O. Yu. Bielikova ◽  
N. A. Matvieieva ◽  
L. S. Yastremskaya ◽  
A. B. Tashyrev
Keyword(s):  
Microbial Communities ◽  
Toxic Metals ◽  
Maximum Permissible Concentration ◽  
Lag Phase ◽  
Nitrogen Fixing ◽  
Natural Ecosystems ◽  
Colony Forming Units ◽  
High Concentrations ◽  
The Stability

Aim. The aim of the work was to determine the stability of nitrogen-fixing microorganisms isolated from the rhizosphere of bromelia (Ecuador), to the effect of toxic metals. Methods. Microorganisms were isolated on the Ashby nutrient medium. The selected strains were cultured on a medium with Cu2+ (Cu (ІІ) citrate) from 50 to 500 mg/l by cation in steps of 50; Ni2+ (NiCl2) from 20 to 200 mg/l by cation in steps of 20; Cr (VI) (K2CrO4) from 20 to 100 mg/l with Cr (VI) in increments of 20. The growth of microorganisms in the presence of metals was characterized by the maximum permissible concentration (MPC) of metals, duration of lag phase and the number of colony-forming units (CFU) of nitrogen-fixing microorganisms with increasing concentration of toxic metals. Results. The selected dominant nitrogen-fixing microorganisms from the soil of Ecuador were resistant to toxic metals (Cu2+, Ni2+, Cr (VI)) in high concentrations. It was found that MPC for microbial communities of nitrogen-fixing microorganisms were: 40 mg/l Cr (VI), 300 mg/l Cu2+ and 100 mg/l Ni2+. Conclusions. It was shown that the selected dominant nitrogen-fixing microorganisms from the Ecuadorian soil were resistant to toxic metals (Cu2+, Ni2+, Cr (VI)) in high concentrations, which in 4–30 times exceed the damage or bactericidal concentrations for the majority of known organophosphate microorganisms of natural ecosystems. Keywords: metalresistance, nitrogen-fixing microorganisms, Cu2+, Ni2+, Cr (VI).

scholarly journals Direct Determination of Glutathione Reductase in Cells Cultured in Microtitre Plates as a Biomarker for Oxidative Stress

1995 ◽  
Vol 23 (4) ◽  
pp. 531-538
Author(s):  
Concepción García-Alfonso ◽  
Pilar Sanz ◽  
Guillermo Repetto ◽  
Manuel Repetto ◽  
Juan López-Barea
Keyword(s):  
Oxidative Stress ◽  
Glutathione Reductase ◽  
Potassium Phosphate ◽  
Direct Determination ◽  
Vero Cells ◽  
Control Activity ◽  
Wide Range ◽  
Cells Cultured ◽  
In Cells

— A new method was developed for the direct determination of glutathione reductase (GOR) activity in Vero cells cultured in microtitre plates, avoiding cell-free extract preparation. The cells in each well were washed twice with phosphate-buffered saline, lysed with Triton X-100, and assayed in 0.1M potassium phosphate, pH 7.0. After subtracting oxidase activity, which increased with NADPH concentration, the net GOR activity was similar at different oxidised glutathione (GSSG) and NADPH concentrations, thus confirming enzyme saturation. The optimised GOR assay used 2.5mM GSSG and 0.12mM NADPH; 5mM EDTA was also added to prevent the enzyme from redox inactivation. The GOR activity was directly proportional to the number of cells per well for a wide range of cell densities, thus supporting the assay's validity for use with cultured cells. The effects on GOR activity of three chemicals which induce oxidative stress, namely, paraquat, iron (II) chloride and iron (III) chloride, were examined to validate the assay under experimental conditions. The specific enzymatic activity increased to 357% of untreated control activity in 5mM paraquat-treated cells, and to 407% of control activity in cells exposed to 7.5mM iron (II) chloride. By contrast, activity decreased to 56% of control activity in cells exposed to 5mM iron (III) chloride. In conclusion, the changes in GOR activity detected in Vero cells confirm that the new assay is suitable for routine in vitro screening of toxicants capable of inducing oxidative stress.

The Direct Determination of I131 in Heterogeneous Fecal Specimens

1961 ◽  
Vol 41 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Arthur F. Dratz ◽  
James C. Coberly
Keyword(s):  
Direct Determination

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

A comparative technique using as Joint studying to prove structure and determination the Quantitative estimation of organic compound (Irbesartan) as drug in multicomponent tablet form

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Imad Tarek Hanoon ◽  
Abed Mohammed Daheir AL-Joubory 2 ◽  
Marwa Mohamed Saied 3
Keyword(s):  
Mobile Phase ◽  
Chemical Structure ◽  
Quantitative Estimation ◽  
Potassium Phosphate ◽  
Hplc Method ◽  
Pharmaceutical Dosage Forms ◽  
Tablet Form ◽  
Rp Hplc ◽  
Percent Recovery

A simple , specific, accurate and precise RP-HPLC method was developed for determination of Irbesartan (IRB) in pharmaceutical dosage forms in tablets products and sachet using symmetry (L 1 ) column at 30°C . The signal was detected at 225 nm. A mobile phase dissolve 0.5 g of buffer potassium phosphate in 100 ml distilled water and adjust pH 2.7 , methanol and acetonitrile at ratio (40 :30 :30 ) . and flow rate 1.2ml/min -1 at pH=7.2 a mobile phase The percent recovery was detected 101 % and the linearity of concentration was 10-50 µg.ml -1 and supported this method by using (FT.I.R.) spectrum method for organic spectrophotometer to prove the chemical structure of this drug and some physical properties . we are obtained the result is identical of other literature . The proposed method was applied successfully for determination of the IRB in tablets products.

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