About: Potassium dichromate is a(n) research topic. Over the lifetime, 1430 publication(s) have been published within this topic receiving 18967 citation(s). The topic is also known as: Potassium dichromate(VI) & Chromium potassium oxide.
Papers published on a yearly basis
TL;DR: In this paper, a procedure has been developed which enables uranium to be determined without chemical separation in solutions containing iron, plutonium, nitrate and many other foreign ions, which interfere in conventional redox methods.
Abstract: A procedure has been evolved which enables uranium to be determined without chemical separation in solutions containing iron, plutonium, nitrate and many other foreign ions, which interfere in conventional redox methods. All of the operations needed are carried out in one vessel, in the cold. An excess of iron(II) sulphate is employed to reduce uranium(VI) to uranium(IV) in a concentrated phosphoric acid solution containing sulphamic acid. The excess of iron(II) is subsequently oxidised by nitric acid in the presence of molybdenum(VI) as catalyst. After adding sulphuric acid and diluting the mixture with water, the determination is completed by titration with standard potassium dichromate solution in the usual manner, using barium diphenylamine sulphonate as indicator.
TL;DR: From the failure to select lymphocytes directed specifically against a chromium determinant of a particular valence it is concluded that by sensitization with chromium salts of different valences a common determinant or closely related determinants are formed.
Abstract: Guinea pigs sensitized with either the trivalent chromium chloride or the hexavalent potassium dichromate are capable of reacting in vivo and in vitro to challenges with both chromium salts This double reactivity is retained also after repeated restimulations with only 1 of these chromium compounds From the failure to select lymphocytes directed specifically against a chromium determinant of a particular valence it is concluded that by sensitization with chromium salts of different valences a common determinant or closely related determinants are formed It is suggested that this determinant is formed by chromium in the trivalent form
TL;DR: In this article, the structure, doping, conductivity and thermal stability of reduced polyaniline (PANI-R) were studied by elemental analysis, FT-i.r., solid-state 13C-NMR, XPS and TGA.
Abstract: HCI-doped emeraldine form of polyaniline (PANI-H) was synthesized by oxidative polymerization of aniline in aqueous hydrochloric acid solution using potassium dichromate as an oxidant. The undoped form of PANI-H (i.e. PANI) was chemically reduced using hydrazine as the reductant. The structure, doping, conductivity and thermal stability of the reduced polyaniline (PANI-R) were studied by elemental analysis, FT-i.r., solid-state 13C-NMR, XPS and TGA. It was found that most of the quinoid structural units in PANI were reduced to benzenoid structural units. PANI-R had been doped with HCI and iodine, but only the iodine-doped product (PANI-RI) showed high electrical conductivity. FT-i.r. and XPS results indicated that some of the benzenoid structural units in PANI-R were oxidized to quinoid structural units during the iodine-doping process and a highly conjugated π system might be formed in the PANI-RI molecular chains. TGA results indicated that PANI-R had better thermal stability than PANI. The dopants—HCl and iodine—were almost completely removed from the HCl and iodine-doped polyanilines below 250°C. PANI-R could also be oxidized by potassium dichromate. The thermal stability of the intrinsically oxidized PANI-R (PANI-RO) was unexpectedly poor. The electrical conductivity of HCl-doped PANI-RO was much lower than that of HCl-doped PANI.
TL;DR: The comet assay did not indicate the involvement of oxidative mechanisms in the DNA-damaging activity of trivalent chromium and it is speculated that its binding to cellular ligands may play a role in its genotoxicity.
Abstract: Chromium can be found in the environment in two main valence states: hexavalent (Cr(VI)) and trivalent (Cr(III)). Cr(VI) salts are well known human carcinogens, but the results from in vitro studies are often conflicting. Cr(VI) primarily enters the cells and undergoes metabolic reduction; however, the ultimate product of this reduction, Cr(III) predominates within the cell. In the present work, we compared the effects of tri- and hexavalent chromium on the DNA damage and repair in human lymphocytes using the alkaline single cell gel electrophoresis (comet assay). Potassium dichromate induced DNA damage in the lymphocytes, measured as the increase in comet tail moment. The effect was dose-dependent. Treated cells were able to recover within a 120-min incubation. Cr(III) caused greater DNA migration than Cr(VI). The lymphocytes did not show measurable DNA repair. Vitamin C at 50 μM reduced the extent of DNA migration. This was either due to a decrease in DNA strand breaks and/or alkali labile sites induced by Cr(VI) or to the formation of DNA crosslinks by Cr(VI) in the presence of vitamin C. Vitamin C, however, did not modify the effects of Cr(III). Catalase, an enzyme inactivating hydrogen peroxide, decreased the extent of DNA damage induced by Cr(VI) but not the one induced by Cr(III). Lymphocytes exposed to Cr(VI) and treated with endonuclease III, which recognizes oxidized pyrimidines, displayed greater extent of DNA damage than those not treated with the enzyme. Such an effect was not observed when Cr(III) was tested. The results obtained suggest that reactive oxygen species and hydrogen peroxide may be involved in the formation of DNA lesions by hexavalent chromium. The comet assay did not indicate the involvement of oxidative mechanisms in the DNA-damaging activity of trivalent chromium and we speculate that its binding to cellular ligands may play a role in its genotoxicity.
TL;DR: The distinctive sensitivity of the four Salmonella strains tested suggested that hexavalent chromium directly interacts with bacterial deoxyribonucleic acid by causing both frameshift mutations and basepair substitutions.
Abstract: Four hexavalent and two trivalent chromium compounds were tested for toxicity and mutagenicity by means of the Salmonella typhimurium/mammalian-microsome test All hexavalent compounds yielded a complete inhibition of bacterial growth at doses of 400 to 800 mug/plate, a significant increase of his/sup +/ revertant colonies at doses ranging from 10 to 200 mug, and no effect at doses of less than 10 mug The distinctive sensitivity of the four Salmonella strains tested (TA1535, TA1537, TA98, and TA100) suggested that hexavalent chromium directly interacts with bacterial deoxyribonucleic acid by causing both frameshift mutations and basepair substitutions The latter mutations, which are prevalent, are amplified by an error-prone recombinational repair of the damaged deoxyribonucleic acid On the average, 1 mumol of hexavalent chromium yielded approximately 500 revertants of the TA100 strain, irrespective of the compound tested (sodium dichromate, calcium chromate, potassium chromate, or chromic acid) The mutagenic potency of the hexavalent metal was not enhanced by adding the microsomal fraction of rat hepatocytes, induced either with sodium barbital or with Aroclor 1254 The two trivalent compounds (chromium potassium sulfate and chromic chloride), with or without the microsomal fraction, were neither toxic nor mutagenic for the bacterial tester strains
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