Showing papers on "Potassium dichromate published in 2002"

Combination effect of light and toxicity in algal tests.

Abstract: The sensitivity of Scenedesmus subspicatus against potassium dichromate is positively correlated to the photon flux density during the algal growth inhibition test. Low photon flux densities led to significantly reduced maximum effects and higher EC 50 levels. To improve the testing of colored substances, we distinguished between the toxic effect (chemical part, represented by potassium dichromate) and the shading effect (physical part, simulated by reduced light intensities during the test) of a hypothetical light absorbing substance. The contribution of these single effects to the total inhibition varied greatly. At high concentrations of potassium dichromate (1.6 and 3.2 mg L -1 ) the physical part never exceeded 25% of the total inhibition, not even at strongest light reduction, while at low concentrations (0.2 and 0.4 mg L -1 ) the physical effect became more prominent when halving the amount of available light. Further, the combination effect of the chemical and the physical effect could he calculated well only by using the concept of independent action. Thus, if chemical and physical effects are measured in combination, as is the case in tests with dyestuffs, the current test protocol for the algal growth inhibition test may lead to incorrect estimations of the toxic potential.

Role of different valence states of chromium in the elicitation of allergic contact dermatitis.

Abstract: Chromium, a known contact sensitizer, is present at high levels in certain detergent bars (40-50 p.p.m.) sold in India. A concern was whether chromium present in such detergent bars could sensitize users or their use lead to the elicitation of allergic contact dermatitis. Chromium present in detergent bars was analyzed for its valence state. It was found to be trivalent [Cr (III)] and not hexavalent [Cr (VI)]. An elicitation test on normal volunteers, as well as on volunteers who were sensitive to chromium, was carried out to determine the elicitation potential of chromium (III) in the bars. Of the 48 volunteers who completed the study, 30 did not show any positive response to either potassium dichromate, the positive control, or the detergent bar containing chromium (III). 18 volunteers who were identified as chromium-sensitive showed a positive response to potassium dichromate but not to the detergent bar containing trivalent chromium. This study clearly showed that the detergent bar with 40-50 p.p.m. of trivalent chromium did not elicit any allergic contact dermatitis even in individuals known to be chromium-sensitive. Hexavalent chromium (potassium dichromate) did however, elicit allergic contact dermatitis in these subjects.

Spectrophotometric method for the determination of nifedipine with 4-(methylamino)phenol and potassium dichromate.

Abstract: A new simple, sensitive and reproducible spectrophotometric method for the determination of nifedipine in pure and dosage forms has been proposed. It is based on the reduction of nifedipine with Zn/NNH4Cl, followed by coupling with N-methyl-1,4-benzoquinoneimine--the oxidation product of 4-(methylamino)phenol, to give a chromophore which absorbed maximally at 525 nm. The experimental conditions were optimised and Beer's law was obeyed over the concentration range of 5-175 microg ml(-1). The molar absorptivity, detection limit, recovery and RSD were found to be 1.9 x 10(3) l mol(-1) cm(-1), 1.1 microg ml(-1), 99.7-100.5% and 0.3-0.8%, respectively. The proposed method was compared favourably with the official B.P. method.

The protective role of thiola and soybean seeds against the genotoxicity induced by potassium dichromate in mice.

Abstract: The genotoxic potential of potassium dichromate (K2Cr2O7) was evaluated in vivo in mice using different mutagenic end points. Chromosomal aberrations in bone-marrow and spermatocytes as well as sperm abnormalities in the tested mice were determined. The doses used were 3, 6, 12 mg K2Cr2O7 kg−1 body weight which correspond to 1/16, 1/8, 1/4 the experimental LD50, respectively. The protective roles of i.p. injection with thiola (a synthetic sulfhydryl compound) at 20 mg kg−1 body weight and feeding treatment with soybean seeds (30% of the diet) were also studied. For chromosomal aberration analysis, subacute treatment for a period of 3 weeks were performed. All the tested doses of K2Cr2O7 induced a statistically significant increase in the percentage of chromosomal aberrations in both somatic and germ cells with dose and time relationships. The percentage of the induced chromosomal aberrations was significantly minimized in all groups of mice i.p. treated with thiola or fed soybean seeds during the period of treatment. Potassium dichromate also induced a significant increase (P In conclusion, the results demonstrate the genotoxic effect of potassium dichromate in mice. The results also confirm the protective role of thiola and soybean seeds against the genotoxicity of potassium dichromate.

Application of CMC in Flotation Separation of Cu-Pb

Abstract: In the methods of processing copper-lead-zinc polymetallic ores, "depression by sulfurous acid-pulp heating" is high in cost and difficult to realize, "depression by potassium dichromate" is still used for its good indexes but poor environment pollution and high reagent dosage This study uses a depressant combined of CMC and potassium dichromate in copper flotation, and gets a better index with less pollution

Preparation of 14C by Irradiation of Aluminum Nitride in Nuclear Reactor

Abstract: Properties of aluminum nitrides prepared by various methods were analyzed with respect to their use as nitrogen-containing materials for preparing 1 4C by irradiation with thermal neutrons in nuclear reactor. It was found that carbon can be completely isolated from irradiated aluminum nitride using potassium dichromate oxidizing agent. Carbon-14 dioxide can be isolated from the gas mixture with nitrogen and nitrogen oxides formed during oxidation of irradiated nitride by passing through potassium permanganate and sodium hydroxide absorbing solutions.

Chromium incorporated in RNA and DNA.

Abstract: The objective of this study was to examine the effect of Cr(III) (chromium chloride) and Cr(VI) (potassium dichromate) on RNA and DNA-chromium adducts formation in isolated nucleic acids and isolated pig lymphocytes. The incubation of cells with potassium dichromate and chromium chloride at concentrations of 10 and 100 microM results in binding of a 1.2-1.9 fold greater number of chromium atoms to nuclear DNA than to total cellular RNA. The incubation of total cellular RNA and nuclear DNA isolated from lymphocytes with CrCl3 and K2Cr2O7 yielded a binding of 1.1-1.6 fold more of Cr atoms to RNA than to DNA. The number of chromium atoms bound to nucleic acids is higher after incubation with K2Cr2O7 than with CrCl3 in both experimental systems.

The effect of nickel sulphate, potassium dichromate, cobalt nitrate and cadmium sulphate on the proteins of cellular contacts and actin skeleton of cultivated human keratinocytes.

Abstract: UNLABELLED The authors tested the effects of known allergens, namely nickel sulphate, potassium dichromate, cobalt nitrate and cytotoxic cadmium sulphate on the proteins of cellular contacts (vinculin, talin, E-cadherin, desmoplaktin) and actin cytoskeleton (actin filaments) of cultivated human keratinocytes. The localisation of proteins of cellular contacts was detected by means of direct immunofluorescence. The authors have detected a decrease in, and destruction of cellular contact proteins and actin cytoskeleton after testing the effect of all allergens, while the most significant changes were detected in E-cadherin, vunkulin and actin filaments. Desmoplaktin and talin were less damaged. Potassium dichromate caused damage already in concentration of 1 microg/ml. A similar effect of the other two tested haptanes was brought about in concentration being 100-fold higher. CONCLUSION the gained results indicate that the investigation of cellular contact proteins and actin cytoskeleton of cultivated human keratinocytes can possibly become a part of the testing of allergy-triggering potential of chemical substances. (Tab. 1, Fig. 4, Ref. 18.)

Spectrophotometric Estimation Of Sparfloxacin In Tablets

Abstract: Two methods have been developed for estimation of sparfloxacin in tablets. Method A is based on the reduction of ferric ions to ferrous ions by the drug, which further in presence of potassium dichromate as oxidizing agent produces green chromogen measured at 680 nm against reagent blank. The chromoger obeyed linearity over 1.5 to 5.5I¼g/ml. Method B is based on similar reaction using ferric nitrate and potassium ferricyanide which produces blue chromogen measured at 720 nm against reagent blank. The chromogen obeyed linearity over 1.5 to 4.0 I¼g/ml.

Determining chemical oxygen demand

Abstract: Chemical oxygen demand (COD) of water or waste water is determined using colour charts or reference tables obtained using (a) standard glucose solutions and (b) mercuric sulphate, (c) potassium dichromate and (d) sulphuric acid - silver sulphate reagents. Also claimed is a kit for determining COD comprising reagents (a), (b), (c) and (d) plus a photometer and the charts or reference tables and methods of determining COD in effluents using reagents (a) to (d) and the charts or tables.

Study on preparation of hydrated chromic oxide and its thermal decomposition

Abstract: Hydrated chromic oxide was directly synthesized by the reduction of potassium dichromate with sucrose in an autoclave. The course of its thermal decomposition was investigated by using the TG, DTA, XRD, FT - IR and BET specific surface area analysis. The results show that there is an oxidation - reduction process of Cr3 + -Cr6 + -Cr3+ during the thermal decomposition of hy-drated chromic oxide. The presence of O2 accelerates the transformation , which leads to formation of micro crystalline a - Cr2O3. It is also found that some of a - Cr2O3 micro crystallites have been formed before the glow phenomenon occurs at 390 C . The mechanism for this thermal decomposition is discussed.

High-effect water-proof agent

Abstract: The high-effective water-proofing agent for building engineering contains (wt%) 14-30% of organic silicon modified acrylic ester, 2-3% of inorganic calcium salt, 2-3% of inorganic iron salt and/or inorganic ferrous iron salt and 2-3% of inorganic potassium salt and 0.05-1% of pH regulator, and the rest is water. The inorganic ferrous iron salt and potassium dichromate can not be contained simultaneously, and said water-proofing agent is convenient for use, can be used in cement mortar, concrete, base surface of clay brick, stone and tile and mosaic, etc. and its service life is identical to that of building.

Study and inspection on an express determination method chemical oxygen demand by potassium dichromate

Abstract: This method raises sulfuric acid concentration properly and strengthens oxidation efficiency of potassium dichromate. The round trip flow time is cut short from two hours to ten minutes and the method adopts silver nitrate-bismuth nitrate united screening method to eliminate the disturb of chorine ion instead of strenuous noxious mercury sulfuric. Through the determination of the standard sample and the statistical inspection of the determination results, this method is verified that it is notable indifferent from the standard one. But the two methods have the same precisions and exits quite marked linear relation.