Showing papers on "Potassium dichromate published in 1982"
TL;DR: Fat tests were not affected by sample storage time, but protein tests showed variation depending on the interval between milk sample collection and analysis, and no changes were significant in fat and protein analyzed by the infrared method for concentrations of preservative.
49 citations
TL;DR: This procedure is useful for separation and isolation of various species of fatty acid methyl esters and for simple, rapid, and reproducible estimation of microgram quantities of materials by spectrodensitometry of the chromatogram.
30 citations
TL;DR: The observed effects have been attributed to the oxidizing activity ofCr(VI), which subtracts electrons from electron donors involved in metabolic pathways producing ATP, and to the ability of Cr(III), deriving from Cr(VI) reduction, to form stable coordination complexes with ATP precursors and enzymes involved in ATP synthesis.
21 citations
TL;DR: In this article, the revelation of dislocations in KBC crystals by etching in water, alcohls, and in inorganic acids mixes with acetone and alcohols is carried out.
Abstract: An investigation of the revelation of dislocations in potassium dichromate (KBC) crystals by etching in water, alcohls, and in inorganic acids mixes with acetone and alcohols is carried out. It is observed that several solutions including water, alcohols and organic acids produce disslocation etch pits on various faces of KBC crystals. Observations of twining and dissolution anisotorpy of (001) faces are also presented. Etching of (001) cleavage faces of same crystals in an etchant composed from 1 part HNO3 and 3 parts acetone indicates the possible growth of another phase at low temperatures.
20 citations
TL;DR: A patient experienced repeated episodes of facial dermatitis with subsequent development of facial hyperpigmentation, and a positive patch test to potassium dichromate strongly implicated chromium hydroxide, used as a pigment in a commercial toilet soap, as a contact allergen.
Abstract: A patient experienced repeated episodes of facial dermatitis with subsequent development of facial hyperpigmentation. A positive patch test to potassium dichromate strongly implicated chromium hydroxide, used as a pigment in a commercial toilet soap, as a contact allergen. Pigmented cosmetic dermatitis may result from repeated episodes of facial inflammation, due to contact allergy from cosmetics.
20 citations
TL;DR: The capillary method proved superior to the Clausen technique, and potassium dichromate was shown to be a better antigen than chromium chloride.
Abstract: We studied the in vitro conjugation of chromium salts and found that trivalent chromium binds to protein 10 times more strongly than hexavalent chromium. We also investigated the use of two different lymphocyte migration inhibition tests for the diagnosis of chromium allergy. The capillary method proved superior to the Clausen technique, and potassium dichromate was shown to be a better antigen than chromium chloride. The test results correlated well with standard patch tests and we recommend the capillary method for the investigation of difficult cases of suspected chromium allergy.
19 citations
TL;DR: Most of the toxicity of the welding particles 1 week after instillation could be related to the content of soluble CrVI, though the insoluble particles also produced changes at the alveolar surface.
17 citations
TL;DR: The combined use of the two selective systems indicated that chromium induces base-pair substitutions in mammalian cells in culture by exposing cells for 1 h to the chemical.
16 citations
TL;DR: The presence of serum seemed to have a protective and modifying role regarding the effect of the various metal compounds on the DNA synthesis of lymphoid cells from unsensitized guinea pigs.
Abstract: The metal allergens cobalt chloride, mercuric chloride, nickel sulfate and potassium dichromate were tested regarding their effect on the DNA synthesis of lymphoid cells from unsensitized guinea pigs. At certain concentrations in the range of 10(-8) to 10(-6) M, all tested metal compounds stimulated the DNA synthesis of both thymocytes and peripheral lymphocytes after 48 h of culture. The most consistent stimulation with all tested metal allergens was obtained with spleen cells. Thymocytes and spleen cells were stimulated even when the small fraction of adherent cells was eliminated. Mercuric chloride and potassium dichromate were found to be inhibiting at 10(-6) to 10(-4) M, while cobalt chloride and nickel sulfate were less toxic and inhibiting at 10(-4) to 10(-3) M. At 5 h of culture the lowest inhibitory concentration of potassium dichromate was found to be about 100-fold lower than that of nickel sulfate, which may be of practical interest for the choice of concentrations used in human patch test. The lowest concentrations of mercuric chloride and potassium dichromate which at 5 h were inhibitory, were stimulating at 48 h. The presence of serum seemed to have a protective and modifying role regarding the effect of the various metal compounds on the DNA synthesis.
14 citations
13 citations
TL;DR: In this article, a flow-injection analysis is proposed for continuous and rapid determination of chemical-oxygen demand (COD) as a dichromate value in organic-waste-water samples.
Abstract: A useful method, based on the principle of flow-injection analysis, whose flow system is physically analyzed to operate the apparatus, is proposed for the continuous and rapid determination of chemical-oxygen demand (COD) as a dichromate value in organic-waste-water samples. Potassium dichromate in sulfuric acid (1+2) is pumped as an oxidizing and spectrophotometric reagent stream, and D-glucose is successfully used as a standard substance for COD. A redox reaction between potassium dichromate and organic COD substances is carried out at 100 °C in the poly(tetrafluoroethylene) tubing (0.6 mm i.d.×50 m) of the system. The peaks, obtained at 445 nm in the recordings, show a good reproducibility over a wide range of COD values. A sampling rate of 10 samples per hour is achieved even when the residence time is 30 min. The precision with this method is 1.3%. Chloride up to 200 mg dm−3 does not interfere with the determination even if silver or mercury salts are not added.
TL;DR: The effect of irradiation temperature on the response of potassium dichromate solutions to 60Co γ-rays has been studied in this paper, and the effect is one of the largest yet reported for any suggested aqueous dosimeter, with a decrease in G(−Cr2O2−7) of 0.39% per °C at 25°C.
01 Jan 1982
TL;DR: In approaching the question as to which test preparations are most suitable for patch testing of metals, 25 chromium sensitive patients were tested with 0.5% potassium dichromate either in water or petrolatum and the aqueous solution proved better than the petrolatum preparation at a 48 h reading with Neodermtest Roc.
Abstract: In approaching the question as to which test preparations are most suitable for patch testing of metals, 25 chromium sensitive patients were tested with 0.5% potassium dichromate either in water or petrolatum. The aqueous solution proved better than the petrolatum preparation at a 48 h reading with Neodermtest Roc. No difference in sensitivity was recorded between 4 hexavalent chromium salts. 3 patients who were only sensitive to chromium solution in water also reacted positively to a 1% cobalt chloride solution and a 5% nickel sulfate solution in petrolatum.
TL;DR: The effects of toxic concentrations of potassium dichromate (K2Cr2O7) and chromic sulphate (Cr2S3O12) on the growth and germination of mungbean Phaseolus aureaus L. seedlings are reported.
TL;DR: The optimum conditions for drying primary-standard or SRM grade potassium dichromate have been further examined, and it has been established that if organic impurities are present in the material the drying temperature should not exceed 200.
Patent•
14 Apr 1982
TL;DR: In this paper, an etching soln is proposed to provide a mirror-finished surface with high reproducibility in etching depth, and the shape of the cross-section of the etched crystal is independent of the crystal orientation.
Abstract: PURPOSE:To provide the titled etching soln contg an alkali dichromate, hydrochloric acid and acetic acid, giving a mirror-finished surface, and having high reproducibility in etching depth CONSTITUTION:This etching soln is an aqueous soln contg an alkali dechromate such as potassium dichromate or sodium dichromate, hydrochloric acid and acetic acid When a crystal of a III-V group compound is etched with the etching soln, the formation of etching pits can be prevented, and a mirror-finished surface can be obtd with high reproducibility in etching depth The shape of the cross-section of the etched crystal is independent of the crystal orientation, so the etching soln can be used well as an etching soln for mesa etching
TL;DR: In this paper, a sample-preparation procedure that minimises oxidation of iron(II) is described, which is suitable for batch working and is shown to achieve good results in various international reference rocks.
Abstract: A rapid method, suitable for batch working, is described for determining iron(II) in silicates. Hot 1 + 1 hydrofluoric-sulphuric acid decomposes the subsample in a polypropylene bottle previously filled with carbon dioxide. After dilution with a boric-phosphoric-sulphuric acid mixture, iron(II) is titrated gravimetrically with potassium dichromate solution, in the bottle used for sample decomposition. A sample-preparation procedure that minimises oxidation of iron(II) is described. Results obtained for iron(II) in various international reference rocks by the proposed method agree well with recommended values.
TL;DR: In this article, a simple method of sample pre-concentration that utilises a permanganate solution trap is described, which has a limit of detection of 1.6 ng l-1 with a total standard deviation of less than 2 ng l−1 or 7% of the concentration.
Abstract: Direct determination of mercury by cold-vapour atomic fluorescence is insufficiently sensitive to monitor nanogram per litre levels of mercury in raw and potable waters. A simple method of sample pre-concentration that utilises a permanganate solution trap is described. The pre-concentration step takes 5 min per test and requires only 250 ml of sample. The procedure has a limit of detection of 1.6 ng l–1 with a total standard deviation of less than 2 ng l–1 or 7% of the concentration. The method results in a bias of less than 3 ng l–1 or 10% of the concentration for both inorganic and total mercury and has a linear range of 0–700 ng l–1. Suitable procedures for digestion of organomercury complexes using potassium persulphate and for preservation of samples for periods of up to 1 week by addition of potassium dichromate and nitric acid are also described.
TL;DR: The relatively poorly water-soluble herbicide Symasin can be oxidized biochemically to a low degree and chemically with potassium dichromate to 73% as discussed by the authors.
Abstract: The relatively poorly water-soluble herbicide Symasin can be oxidized biochemically to a low degree and chemically with potassium dichromate to 73%. With potassium permanganate, on the other hand, only about 5% of the theoretical chemical oxygen demand are consumed. As investigations with municipal wastewaters have shown, by the aerobic wastewater treatment Symasin is not decomposed also with extended treatment times and very intensive aeration. Only at very high dosages Symasin has a toxic effect on warm-blooded animals; various algae species, on the other hand, and also nitrifying bacteria react very sensitively.
TL;DR: A method for the determination of total iron in iron ores and concentrates is described which avoids the use of mercuric chloride and shows the same degree of precision, accuracy, and degree of interference as those obtained by the standard stannous chloride-mercuric chloride method.
TL;DR: In this article, it was shown that the mobility of charge carriers decreases with increasing density of crosslinks giving rise to increase in charge storage capacity, and it was also shown that crosslink crosslinks increase the storage capacity of polyvinyl alcohol.