نتایج جستجو برای: chromium sampling method
تعداد نتایج: 1795033 فیلتر نتایج به سال:
A new method for the speciation of ng/mL concentrations of Cr(III) and Cr(VI) solutions with analysis by laser-induced breakdown spectroscopy (LIBS) is reported. Speciation is achieved by pre-concentration of the chromium onto commercially available cation exchange polymer membranes. Chromium(III) is removed directly by cation exchange; chromium(VI) in the filtrate is reduced to Cr(III) and con...
The total content of chromium in natural waters does not generally exceed several μg/l. Thus, it is obvious that various forms of chromium will occur at the levels of tenths or hundredths of μg/l. Their determination requires the application of a sufficiently sensitive method, but its specificity has an important role to play in the case of chemical individuals or selectivity in regard to speci...
— Salen type chromium Schiff base complex was synthesized by microwave irradiation. The complex was characterized by UV-visible, FT-IR spectroscopy and EPR spectroscopy. Electrochemical property of chromium complex was tested with the aid of cyclic voltammetry (CV). The synthesized chromium Schiff base complex was electrochemically polymerized and used for the detection of hydroquinone. Chromiu...
Chromium is present in the environment in several different forms. The most common forms are chromium(0), chromium(III) (or trivalent chromium) and chromium(VI) (or hexavalent chromium). Chromium(III) occurs naturally in the environment and is an essential nutrient that helps the human body utilize sugar, protein and fat. Chromium(VI) and chromium(0) are generally produced by industrial process...
Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmiu...
Introduction The identification and quantification of hexavalent chromium in solid samples is an important factor in characterization studies. The speciation of elements is a developing feature of analytical methods; the evaluation of the environmental and biological impact of the Cr (VI) compounds on environmental matrices is fundamental because of their demonstrated toxicity and potential car...
abstract: research purpose: the purpose of this research is to identify academic databases assessment factors and criteria at law and political science majors. the necessity of this research is to distinguish academic databases assessment factors and criteria and to identify the most important ones and rank them in order to select an appropriate database according to students’ and faculty memb...
This contribution deals with the waste from the processes in which raw hide is transformed into leather, as well as with the waste generated during further leather processing and the final waste of leather industry, the worn-out shoes. All this waste, if deposited in the open-air dumps, represents a potential threat to human health, because it contains trivalent chromium (Cr III), which can oxi...
Chromium is one of the hazardous pollutants in industrial effluents. In this study, a new nano-boehmite modified with sodium dodecyl sulphate is developed for preconcentration trace amounts of chromium ions as a prior step to its determination by flame atomic absorption spectrometry. We investigated the effect of various parameters on the recovery of the analyte ions, including pH of sample solut...
A company produces 1000 metal cylinders a day for 10 days. The government Safety Authority will take a random sample of cylinders, take a random sample of locations within each of these cylinders, and test for percentage Nickel (Ni) and percentage Chromium (Cr). For each sample in which the percentages are outside some intervals, they fine the company e1,000,000. If the proportion of percentage...
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