Concentrations Of Potassium Dichromate Research Articles

Bioaccumulation of chromium in red swamp crayfish ( Procambarus clarkii)

Crayfish were exposed to a range of potassium dichromate concentrations (0.15, 0.30, 3.0 and 30 mg l −1) for periods up to 7 weeks. Chromium bioaccumulation in all tissues over the 7 week exposure period was not consistently time- and dose-dependent. The order of distribution of chromium into the various tissues was dependent upon the exposure concentration of the metal. Chromium clearance studies conducted 1 and 3 weeks following exposure demonstrated a concentration reduction in most tissues only at the highest exposure concentration of chromium (30 mg l −1). Histological studies demonstrated damage to both the gills and hepatopancreas at the lowest exposure concentration. The results suggest that the red swamp crayfish, Procambarus clarkii, is a useful biomarker for chromium exposure.

Biofilm concentration of chromium

Abstract Removal of chromium from synthetic waste streams was studied using biofilms that developed on disks of a laboratory scale Rotating Biodisk Contactor (RBC). During its development the biofilm was continuously exposed to various concentrations of potassium dichromate. Chromium removal efficiency was about 98% during steady state addition of chromium (VI) at concentrations of 100 or 200 mg l‐1. Analysis of the major soluble chromium ions demonstrated that chromium (VI) was first reduced to chromium (III) which then appeared to be adsorbed by the biofilm. Chromium levels associated with the biofilm were found (by chemical analysis) to be 6.5–7.0% of its dried weight.

Effects of hexavalent chromium on trout mitochondria

Trout liver mitochondria were incubated in the presence of micromolar concentration of potassium dichromate (Cr(VI)) under several experimental conditions. Cr(VI) strongly inhibited both state 3 and state 4 of respiration supplemented by NAD-linked substrates; it also slightly affected the respiration of FAD-linked substrates. Evidence is provided that the respiratory inhibition induced by dichromate is partially coupled to the Cr(VI) reduction mechanism occurring in mitochondria.

Effects of sublethal concentrations of potassium dichromate on the occurrence of splenic melano‐macrophage centres in juvenile plaice, Pleuronectes platessa, L.

Plaice were exposed to 0.5 and 2.0 ppm potassium dichromate (K2Cr2O7) concentrations for 27 days. In both water concentrations chromium was accumulated up to a level of 400 ppb in the carcass of the fish. At the same time the number of splenic melano‐macrophage centres (MMC) tripled, whereas their average size was reduced to one third. The percentage area of MMC in the splenic tissue remained unchanged. Histological alterations following exposure to K2Cr2O7 included increases both in melanin content of the MMC and in the number of melanin‐containing cells within blood vessels; also, the splenic ellipsoids became less clearly demarcated. Splenic melano‐macrophages show a decreased ability to aggregate to form large MMC under the influence of K2Cr2O7, which leads to the assumption that the turnover rate of macrophage settlement in, and macrophage elimination from, the spleen is increased.

The effect of potassium dichromate and mercuric chloride on urinary excretion and organ and subcellular distribution of [ 203Hg]mercuric chloride in rats

The mechanism by which subthreshold/non-effective doses or concentrations of potassium dichromate (K 2Cr 2O 7) potentiate the effect of moderately effective dose/concentrations of mercuric chloride (HgCl 2) on renal organic ion transport is not understood. To investigate this effect, the rate of excretion of mercury from the intact animal and the renal and hepatic accumulation and subcellular distribution of mercury within kidney cortex following pretreatment or in vitro exposure to K 2Cr 2O 7 were undertaken. Coincidental administration of K 2Cr 2O 7 had no significant effect in altering the rate of excretion of labeled mercury. Organ distribution showed time dependence; however, the presence of K 2Cr 2O 7 did not increase renal mercury concentrations. In fact, significantly less mercury was found at 4 h in the kidneys of rats receiving both metal salts. Subcellular distribution of labeled mercury ( 203Hg) was also not significantly altered by the presence of K 2Cr 2O 7, although the distribution patterns for in vitro exposure and pretreated tissues were different. These studies show that K 2Cr 2O 7 does not produce alterations in urinary elimination, organ distribution or subcellular distribution of mercury.

Performance of the Hitachi 705 evaluated.

We evaluated a new discrete analyzer, the Hitachi 705. The instrument can process sequentially as many as 19 different enzymes or other analytes, with a throughput of 180 tests per hour. We evaluated the spectrophotometer, the sample and reagent probes, and the performance for 11 assays: creatine kinase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltransférase, amylase, glucose, urea nitrogen, creatinine, albumin, calcium, and phosphorus. The total imprecisions (within-day plus day-to-day component of imprecision) (CV) were: for the photometer (six concentrations of potassium dichromate), 0.14 to 0.4%; for the serum probe (55 to 20 microL), 0.4 to 1.0%; for the reagents probes (50 to 350 microL), 0.3 to 1.2%; for the enzymatic procedures, 2.0 to 8.0%; and for the other tests (glucose, urea nitrogen, creatinine), 1.0 to 4.0%. Good linearity was obtained in the proposed range for the 11 tests, except for calcium. Comparison of the total analytical error with the medically allowable error at a decision value showed that the test results were acceptable, except for calcium and phosphorus. The instrument showed good reliability and practicability.

Leukocytes from patients allergic to chromium and nickel examined by the sealed capillary migration technique.

Leukocytes from patients allergic to chromium and nickel were studied by a sealed capillary migration test. The migration indices were determined at 2, 5 and 24 h. The chromium-allergic group could be differentiated from the control group at all investigated times, and especially at 2 and 5 h, by using a potassium dichromate concentration of 1.7 x 10(-5) M in the capillaries. The migration indices in the nickel-allergic group could not be used for discrimination from the controls. The highest chromate (1.1 x 10(-4) M) and nickel sulfate (3.8 x 10(-4) M0 concentrations inhibited the migration of leukocytes from both patients and controls, indicating toxic effects.

Effects of Potassium Dichromate and Sample Storage Time on Fat and Protein by Milko-Scan and on Protein and Casein by a Modified Pro-Milk Mk II Method

A rapid procedure is described for measuring casein in milk by a combination of isoelectric precipitation and amido black dye-binding. Individual milk samples from 3 8 cows were subsampled, preserved with potassium dichromate at a concentration of 8 mg/ml of milk, and analyzed for fat and protein by the Milko-Scan 300 and for protein and casein by the dye-binding procedure on day 1, 4, 7, and 10 after milk collection. Fat tests were not affected by sample storage time, but protein tests showed variation depending on the interval between milk sample collection and analysis. In a separate study effects of potassium dichromate used as a preservative at 0, 2, 4, 6, 8, and 12 mg/ml of milk on chemical determinations were investigated. No changes were significant in fat and protein analyzed by the infrared method for concentrations of preservative. There were no significant differences in protein determination by the two methods for nonpreserved samples. For preserved samples, the dye-binding method for protein gave determinations higher than those by the infrared method. The difference increased linearly with increasing concentration of potassium dichromate at .07% in protein for every 2mg of potassium dichromate per milliliter of milk.

Regulation of enzyme activity in mungbean Phaseolus aureus L. seedlings by chromium

The effects of toxic concentrations of potassium dichromate (K 2Cr 2O 7) and chromic sulphate (Cr 2S 3O 12) on the growth and germination of mungbean Phaseolus aureaus L. seedlings are reported. These effects included inhibition of hypocotyl elongation and fresh and dry weight increase in the presence of chromium salts, dichromate being relatively more toxic than chromic sulphate. The activity of catalase, peroxidase, IAA-oxidase, ascorbic acid oxidase and dehydrogenase increased in response to chromium addition. This stimulation of enzyme activity was synchronised with a similar increase in soluble protein formation.

Effect of metal allergens on the DNA synthesis of unsensitized guinea pig lymphoid cells cultured in vitro.

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.

Patch tests with potassium dichromate removed after 24 and 48 hours.

The rate of release in vitro of four potassium dichromate concentrations (0.5, 0.1, 0.05 and 0.01%) was determined. In the course of 24 h, 90.1-97.5% was released of the total K2Cr2O7 amount in 48 h. Out of 30 patients positive to 0.05% dichromate when the patch test was done routinely, 29 were also positive when the patch was removed after 24 h. The effect of the earlier removal of the patch test was also noted in seven other patients, when results of tests with lower dichromate concentrations were taken into account.

Acidic Potassium Dichromate Solutions as Ultraviolet Absorbance Standards.

The absorbances of five concentrations of potassium dichromate in 0.001 M perchloric acid have been determined at eight wavelengths in the ultraviolet on the National Bureau of Standards Institute for Materials Research high-accuracy spectrophotometer. Four of the wavelengths—235, 257, 313, and 350 nm—correspond to absorbance maxima or minima in the HCrO4– spectrum and are useful wavelengths for checking the accuracy of the absorbance scale of narrow bandpass spectrophotometers. Although partial dimerization of HCrO4– to Cr2O7= produces small positive deviations from Beer’s law at these wavelengths, the apparent absorptivities calculated for each concentration are reproducible to one part in a thousand. The estimated uncertainties in the absorptivity values are ± 0.7 percent at 0.1 absorbance (A) and ± 0.2 percent near A = 1. These uncertainties include all known sources of possible systematic error and the 95 percent confidence level for the mean. The remaining four wavelengths used for measurement are near two predicted isosbestic points in the HCr04–/Cr2O7= spectra. The absorptivities at 345 nm are sufficiently independent of concentration that this wavelength can be used for checking absorbance linearity to one part in a thousand over the range A = 0.2–1.

Sulfuric Acid Concentration in the Catalyzed Breathalyzer Ampules

During the last fifteen years the Breathalyzer has been the most widely used instrument in North America for determining blood alcohol concentrations by means of breath analysis [1,2]. Of the parameters which may affect the alcohol readings, those related to the composition of the ampule reagent are among the most important. At present the manufacturing specifications used by Scientific Services are, by volume, 50 percent aqueous sulfuric acid, 0.025 percent weight per volume, potassium dichromate, and 0.025 percent weight per volume, silver nitrate [3]. The total volume of this solution in the ampules may be 3.00 to 3.07 ml. The inclusion of the silver nitrate as a catalyst is a modification of the original formulation which involved only the potassium dichromate in the aqueous sulfuric acid solution [4]. It has been shown that the potassium dichromate concentration may vary between 0.015 percent and 0.035 percent weight per volume, and the sulfuric acid concentration may vary between 16 and 20 normal without loss in accuracy [5]. Under these conditions ethanol samples introduced into the ampules at approximately 65 C were oxidized stoichiometrically to acetic acid within 90 s [1]. The ethanol is first oxidized to acetaldehyde, a short-lived intermediate, rapidly oxidized to acetic acid. Stronger oxidizing conditions than exist in the ampule are needed to take the oxidation beyond the acetic acid stage [2,6,7]. The equations representing the stoichiometry of this progressive oxidation of ethanol are as follows: 1) 2K2Cr2O7 + 8H2SO4 → 2Cr2(SO4)3 + 2K2SO4 + 8H2O + 6O2) CH3CH2OH + O → CH3CHO + H2O 3) CH3CHO + O → CH3COOH 4) CH3COOH + 4O → 2CO2 + 2H2O