Three-dimensional mesoporous chromium oxide: a highly efficient material for the elimination of volatile organic compounds.
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Journal Article↗
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[SENSITIZATION OF THE SKIN IN CUTANEOUS LESIONS CAUSED BY ANTISCALLING COMPOUNDS].
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Chromium↗
Conditions that influence the genetic activity of potassium dichromate and chromium chloride in Saccharomyces cerevisiae.
Potassium dichromate and chromium chloride were analyzed for their ability to induce mitotic gene conversion and point reverse mutation in D7 diploid strain of S. cerevisiae. We used cells from the stationary phase of growth with and without metabolic activation (S9 hepatic fraction) and cells from the logarithmic phase, that contain a high level of cytochrome P-450 and have a greater permeability. In the present work we confirmed the genetic activity of K2Cr2O7 in cells from the stationary phase, with and without S9 fraction and in cells from the logarithmic growth phase. A slight increase in genetic activity was observed in experiments with CrCl3 using phosphate buffer, but no genetic effects were noted in Tris-HCl buffer. Our studies suggest that phosphate ion may be the carrier responsible of the entrance of trivalent chromium in the cells. The higher cellular permeability may account for the different results obtained with both compounds in cells from the stationary and logarithmic phases of growth.
Biotransformation↗
The chemistry of chromium and some resulting analytical problems.
Chromium, named for its many-colored compounds, exists in the oxidation states of -2 to +6 inclusively. The compounds exhibit a wide range of geometries including square planar, tetrahedral, octahedral, and various distorted geometries. Chromium is found in nature principally as the chromite ore FeCr2O4 in which chromium is in the +3 state. The existence of a particular oxidation state is dependent on many factors including pH, redox potentials, and kinetics. Thermodynamically, +3 and +2 are the most stable states, while the +3 and +6 oxidation states are the most common ones found in aqueous solution. Kinetically, chromium +3 is substitutionally inert: for water exchange k(sec-1) = 2.5 x 10(-6), due to the presence of the half-filled d(t2g)3.4A2g state. On the other hand, protonation/deprotonation is quite rapid. Polymerization is very slow but is promoted at higher pHs; acid cleavage of the protonated oligomers is also quite slow. Chromium +6 as the chromate ion is strongly oxidizing at low pHs and less so in basic solution. The chromate ion does form some polyacids and polyanions. These factors must be considered in analyzing samples for total chromium and for the amounts of each oxidation state.
Chemistry Techniques, Analytical↗
Speciation of chromium dyes by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection.
High-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) was employed for the separation and detection of chromium species in azo dyes, Acid blue 158 and Acid Blue 193; mainly Cr(III) and Cr(VI). The dyes were first analyzed for total metal content using ICP-MS and their stability in solution was studied by measuring their absorbance through a range of pH values. Then an isocratic chromatographic method employing reversed-phase liquid chromatography with mass spectrometric detection was developed. Applying this method to the separation of these dyes, the absolute detection limits of Acid Blue 158 and 193 were 1 and 5 ng respectively. Additionally, Acid Blue 158 did not contain any chromium species. On the other hand, Acid Blue 193 contained uncomplexed and potentially bioavailable Cr(III). Acid Blue 193 did not have any toxic Cr(VI) present in the samples.
Anions↗
Chemistry of the crosslinking of collagen during tanning.
The materials commonly used for crosslinking collagen as part of the process of converting animal hides into leather fall into three main groups: mineral tannages, aldehyde tannages, and "vegetable" tannages. The most important mineral crosslinking agents are hydrated basic chromium III sulfate complexes. These compounds form extended polynuclear coordination complexes containing hydroxol, oxo, and sulfato bridges into which ionized carboxyl groups on collagen enter readily as coordinating ligands accomplishing crosslinking. On pH adjustment and partial drying, highly stable complexes are formed with oxo bridges predominating and protein amide groups entering the coordination complex. The aldehyde tannages proceed through aldehyde condensation reactions with collagen amino groups to give alpha-hydroxyamines which can condense with other collagen amine groups to effect crosslinking. The vegetable type tanning agents, whether natural plant extracts or synthesized, are complex, high molecular weight polyhydroxy compounds that do not rely on crosslinking as such to be effective. Their effectiveness appears to depend on other properties. This and additional information concerning these commerical tannages are reviewed.
Aldehydes↗
Compartments and barriers in the sciatic nerve of the rabbit.
Near constant concentration of various radioactively labelled polar nonelectrolytes were maintained in the blood plasma of renal ligated rabbits. The uptake of [14C]urea, [51Cr]EDTA and [14C]inulin into sciatic nerve was interpreted in terms of a two-compartment model. There was a rapidly equilibrating space representing about 20% of the tissue weight which is almost certainly the interstitial fluid of the epineurium and outer layers of the perineurium. Urea penetrated the blood-nerve barrier at a similar rate to the entry of this compound into brain. Sucrose, chromium-EDTA and sulphate passed into the true interstitial fluid approaching a total volume of distribution of about 36% of the tissue weight at 6-8 h. Since movement of these 3 solutes is severely restricted by the blood-barrier, the blood-nerve barrier in the rabbit must contain channels of greater than 1 nm which are not present in the developed blood-brain barrier. Uptake of [3H]3-O-methylglucose into nerve was examined but the results did not give a conclusive answer to the question of whether there is specific transport of sugars at the blood-nerve barrier. The wet nerve contained (in mmole/kg) sodium 74.3; potassium 42.6 and chloride 48.8. Water was 64.6 ml/100 g. Intracellular electrolyte concentrations were estimated. Approximately 30% of the total sodium content cannot be accounted for as being free in the interstitial fluid at a Gibbs-Donnan distribution with plasma. Analysis of metabolically poisoned nerves which have equilibrated with salt solution in vitro suggests that negatively charged polyelectrolyte molecules retain about 14 mmole of sodium/kg wet normal nerve.
Animals↗
Analysis of metal-induced mutations altering the expression or structure of a retroviral gene in a mammalian cell line.
Carcinogenic metal compounds, with the exception of chromium(VI), have been found to be poorly mutagenic in both prokaryotic and mammalian cell mutagenesis assays, yet they are clearly clastogenic (Hansen and Stern, 1984). Thus, the role of metals as initiators in carcinogenesis has been difficult to delineate. In an effort to develop a model system capable of assaying DNA damage caused by carcinogenic metals, we have investigated the role of NiCl2, CdCl2, Na2CrO4, and NMU in a murine sarcoma virus-infected mammalian cell line in which expression of the retroviral v-mos gene is growth-temperature regulated. This cell line, designated 6m2, contains a single-copy, stably integrated, mutant Moloney murine sarcoma virus DNA (designated MuSVts110) and is temperature sensitive for morphological transformation due to a conditionally defective viral RNA-splicing event that in turn regulates expression of the viral transforming gene. Mutations affecting the viral DNA in 6m2 cells can be detected if these alterations lead to changes in the structure or expression of the transforming protein encoded by the MuSVts110 v-mos gene. Analysis of the viral proteins from 6m2 'revertant' cell lines (as defined by reversion to the transformed phenotype at all growth temperatures) selected after treatment with the above agents showed that NiCl2, NMU, and Na2CrO4 each induced a different yet specific type of mutation. NiCl2 and NMU each altered the temperature sensitivity of viral RNA splicing, possibly due to base substitution mutations, but did so to distinctly different extents. Na2CrO4 affected the structure of the viral proteins by inducing what appear to be short frameshift mutations that resulted in the temperature-dependent translation of a novel virus-encoded transforming protein, P100gag-mos. CdCl2 also induced frameshift mutations but, in one case, induced a mutation which may result from a deletion of about 300 bases within the MuSVts110 DNA.
Cell Line↗
Organic contaminants and trace metals in flounder liver and sediment from the Amsterdam and Rotterdam harbours and off the Dutch coast.
Organic contaminants [polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenylethers (PBDEs), nonylphenols], organotin compounds and trace metals (cadmium, chromium, mercury and zinc) were determined in flounder (Platichthys flesus) liver and sediment from the Amsterdam harbour (North Sea Canal) and Rotterdam harbour (Euromonding) and off the Dutch coast between the Amsterdam and Rotterdam harbour mouths in order to assess the level of contamination in these harbours and to study contamination gradients.
Animals↗
Cleanup worker exposures to hazardous chemicals at a former nuclear weapons plant: piloting of an exposure surveillance system.
Cleanup of former U.S. Department of Energy (DOE) nuclear weapons production facilities involves potential exposures to various hazardous chemicals. We have collaboratively developed and piloted an exposure database and surveillance system for cleanup worker hazardous chemical exposure data with a cleanup contractor at the Rocky Flats Environmental Technology Site (RFETS). A unique system feature is the incorporation of a 34-category work task-coding scheme. This report presents an overview of the data captured by this system during development and piloting from March 1995 through August 1998. All air samples collected were entered into the system. Of the 859 breathing zone samples collected, 103 unique employees and 39 unique compounds were represented. Breathing zone exposure levels were usually low (86% of breathing zone samples were below analytical limits of detection). The use of respirators and other exposure controls was high (87 and 88%, respectively). Occasional high-level excursions did occur. Detailed quantitative summaries are provided for the six most monitored compounds: asbestos, beryllium, carbon tetrachloride, chromium, lead, and methylene chloride. Task and job title data were successfully collected for most samples, and showed specific cleanup activities by pipe fitters to be the most commonly represented in the database. Importantly, these results demonstrate the feasibility of the implementation of integrated exposure database and surveillance systems by practicing industrial hygienists employed in industry as well as the preventive potential and research uses of such systems. This exposure database and surveillance system--the central features of which are applicable in any industrial work setting--has enabled one of the first systematic quantitative characterizations of DOE cleanup worker exposures to hazardous chemicals.
Colorado↗
Immunological detection of DNA-protein complexes induced by chromate.
A select group of non-histone proteins becomes complexed to DNA after Chinese hamster ovary (CHO) cells are treated with potassium chromate. The most abundant complexed protein has a mol. wt of approximately 45 kd and is thought to be actin. An antiserum to the chromate-induced DNA-protein complexes (DPCs) was prepared to facilitate the study of these complexes. Rather than detecting the predominant silver-stained proteins of DPCs described in an earlier study, this antiserum reacts primarily with an acidic 95-kd protein (p95) that does not silver stain. The antiserum can be used routinely to assay for the induction of p95-DNA complexes produced by chromate and perhaps by other carcinogens. Immunofluorescent staining of CHO cells and immunoblotting of cell fractions show the reactive antigens are within the cell nucleus. Blotting experiments with the antiserum indicate the chromate-induced p95-DNA complex dissociates in the presence of 2-mercaptoethanol, suggesting similarity to the DPCs formed by carcinogenic platinum compounds. A reduced species of chromium (probably Cr3+) may form DPCs by binding to the nitrogen, oxygen or sulfur atoms of proteins and DNA. These results illustrate the usefulness of immunological detection methods to study specific DNA-protein interactions induced by carcinogens. The possible relevance of DPCs in the carcinogenic process is discussed.
Animals↗
Properties of IncP-2 plasmids of Pseudomonas spp.
Thirty IncP-2 R plasmids from isolates of Pseudomonas spp. of diverse geographical origins were examined for the production of resistance properties. All the plasmids determined resistance to tellurite and all inhibited the propagation of certain DNA phages, although several patterns of phage inhibition were detected. Of the 30 plasmids, 29 determined resistance to streptomycin, 28 determined resistance to mercuric ion, and 24 determined resistance to sulfonamide. Resistance to other antibiotics, to compounds of arsenic, boron, or chromium, and to UV irradiation was less common. The degradative plasmid CAM also belonged to this group. When CAM was introduced into recipients carrying an IncP-2 R plasmid, recombinant plasmids were often formed in which antibiotic resistance and the ability to grow on camphor were transferred together to further recipients or were lost together in a strain in which IncP-2 plasmids were unstable. Such hybrid plasmid formation was rec dependent. CAM and other IncP-2 plasmids that determine UV light resistance demonstrated UV-enhanced, nonpolarized transfer of the Pseudomonas aeruginosa chromosome. By agarose gel electrophoresis, all IncP-2 R plasmids and CAM were ca. 300 X 10(6) in molecular weight.
Conjugation, Genetic↗
A cancer risk assessment of inner-city teenagers living in New York City and Los Angeles.
BACKGROUND: The Toxics Exposure Assessment Columbia-Harvard (TEACH) project assessed exposures and cancer risks from urban air pollutants in a population of high school teenagers in New York City (NYC) and Los Angeles (LA). Forty-six high school students participated in NYC and 41 in LA, most in two seasons in 1999 and 2000, respectively. METHODS: Personal, indoor home, and outdoor home 48-hr samples of volatile organic compounds (VOCs), aldehydes, particulate matter with aerodynamic diameter < or = 2.5 microm, and particle-bound elements were collected. Individual cancer risks for 13 VOCs and 6 particle-bound elements were calculated from personal concentrations and published cancer unit risks. RESULTS: The median cumulative risk from personal VOC exposures for this sample of NYC high school students was 666 per million and was greater than the risks from ambient exposures by a factor of about 5. In the LA sample, median cancer risks from VOC personal exposures were 486 per million, about a factor of 4 greater than ambient exposure risks. The VOCs with the highest cancer risk included 1,4-dichlorobenzene, formaldehyde, chloroform, acetaldehyde, and benzene. Of these, benzene had the greatest contributions from outdoor sources. All others had high contributions from indoor sources. The cumulative risks from personal exposures to the elements were an order of magnitude lower than cancer risks from VOC exposures. CONCLUSIONS: Most VOCs had median upper-bound lifetime cancer risks that exceeded the U.S. Environmental Protection Agency (EPA) benchmark of 1 x 10-6 and were generally greater than U.S. EPA modeled estimates, more so for compounds with predominant indoor sources. Chromium, nickel, and arsenic had median personal cancer risks above the U.S. EPA benchmark with exposures largely from outdoors and other microenvironments. The U.S. EPA-modeled concentrations tended to overestimate personal cancer risks for beryllium and chromium but underestimate risks for nickel and arsenic.
Adolescent↗
[Chemical state analysis of chromium by the conventional X-ray fluorescence spectrometer].
X-Ray Kbeta emission spectra of chromium and some of their compounds were studied by conventional XRF spectrometer Rigaku 3080 E1 and PEAKFIT spectrum analyzing programs. Some qualitative and quantitative relations were obtained between the true spectrum profile and its parameters (peak position, peak top intensity, FWHM and asymmetry indices) and chemical state by data processing technique. And making use of these relationship, the chemical state distribution were analyzed of chemical chromate treatment film, stainless steel. Satisfactory results were obtained.
English Abstract↗
Nuclear magnetic spin-lattice relaxation of water protons caused by metal cage compounds.
The nuclear magnetic spin-lattice relaxation rates of water protons are reported for solutions of manganese(II), copper(II), and chromium(III) cage complexes of the sarcophagine type. As simple aqueous solutions, the complexes are only modest magnetic relaxation agents, presumably because they lack protons on atoms in the first-coordination-sphere protons that are sufficiently labile to mix the large relaxation rate at the metal complex with that of the bulk solvent. The relaxation is approximately modeled using spectral density functions derived for translational diffusion of the interacting dipole moments with the modification that the electron spin relaxation rate is directly included as a contribution to the correlation time. In all cases studied, the electron spin relaxation rate is sufficiently large that it contributes directly to the water-proton spin relaxation process. The poor relaxation efficiency of the cage compound may, however, be improved dramatically by binding the complex to a protein. The efficiency is improved even further if the rotational motion of the protein is reduced drastically by an intermolecular cross-linking reaction. The relaxation efficiency of the cross-linked protein-cage complexes rivals that of the best first-coordination-sphere relaxation agents like [Gd(DTPA)(H2O)]2- and [Gd(DOTA)(H2O)]-.
Aza Compounds↗
Synthesis of [(HIPTNCH2CH2)3N]Cr Compounds (HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3) and an evaluation of chromium for the reduction of dinitrogen to ammonia.
Red-black [HIPTN3N]Cr (1) ([HIPTN3N]3- = [(HIPTNCH2CH2)3N]3- where HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3 = HexaIsoPropylTerphenyl) can be prepared from CrCl3, while green-black [HIPTN3N]Cr(THF) (2) can be prepared from CrCl3(THF)3. Reduction of {1|2} (which means either 1 or 2) with potassium graphite in ether at room temperature yields [HIPTN3N]CrK (3) as a yellow-orange powder. There is no evidence that dinitrogen is incorporated into 1, 2, or 3. Compounds that can be prepared readily from {1|2} include red [HIPTN3N]CrCO (4), blood-red [HIPTN3N]CrNO (6), and purple [HIPTN3N]CrCl (7, upon oxidation of {1|2} with AgCl). The dichroic (purple/green) Cr(VI) nitride, [HIPTN3N]CrN (8) was prepared from Bu4NN3 and 7. X-ray studies have been carried out on 4, 6, and 7, and on two co-crystallized compounds, 7 and [HIPTN3N]CrN3 (65:35) and [HIPTN3N]CrN3 and 8 (50:50). Exposure of a degassed solution of {1|2} to an atmosphere of ammonia does not yield "Cr(NH3)" as a stable and well-behaved species analogous to Mo(NH3). An attempt to reduce dinitrogen under conditions described for the catalytic reduction of dinitrogen by [HIPTN3N]Mo compounds with 8 yielded a substoichiometric amount (0.8 equiv) of ammonia, which suggests that some ammonia is formed from the nitride but none is formed from dinitrogen.
Ammonia↗
Chromium(VI) and apparent phenotypic reversion in Salmonella TA100.
After treatment with potassium chromate at concentrations causing ultramicroscopic cellular lesions, a significant proportion (up to 75%) of TA100 colonies fail to replicate on fresh minimal plates containing biotin. This suggests that chromium(VI) may not always induce his- reversion to his+ in Salmonella TA100. The terms 'false' or phenotypic reversion have been used to distinguish such instances from 'true' or genotypic reversion, where progeny his+ cells readily grow on biotin replica plates. Results of the present study indicate that the majority of chromate-exposed colonies, initially scored as his-, are identifiable as his+ after 24 h culture on nutrient agar. Moreover, chromate exerts a cytostatic effect on TA100 since early colony development is suppressed at high chromate concentrations. A gradual chemical reduction of chromium(VI) ions by normal media compounds is probably responsible for the re-emergence of colony growth during prolonged incubation of test plates. Thus, temporary growth inhibition at high chromate concentration appears to be responsible for most of the non-replicating colonies detected in mutagenicity assays of chromium(VI).
Chromates↗
Polyoxometalate-supported transition metal complexes and their charge complementarity: synthesis and characterization of [M(OH)6Mo6O18[Cu(Phen)(H2O)2]2][M(OH)6Mo6O18[Cu(Phen)(H2O)Cl]2].5H2O (M = Al(+, Cr3+).
Two Anderson-type heteropolyanion-supported copper phenanthroline complexes, [Al(OH)6Mo6O18[Cu(phen)(H2O)2]2]1+ (1c) and [Al(OH)6Mo6O18[Cu(phen)(H2O)Cl]2]1- (1a) complement their charges in one of the title compounds [Al(OH)6Mo6O18[Cu(phen)(H2O)2]2][Al(OH)6Mo6O18[Cu(phen)(H2O)Cl]2].5H2O [1c][1a].5 H2O 1. Similar charge complementarity exists in the chromium analogue, [Cr(OH)6Mo6O18[Cu(phen)(H2O)2]2][Cr(OH)6Mo6O18[Cu(phen)(H2O)Cl]2].5 H2O [2c][2a].5 H2O 2. The chloride coordination to copper centers of 1a and 2a makes the charge difference. In both compounds, the geometries around copper centers are distorted square pyramidal and those around aluminum/chromium centers are distorted octahedral. Three lattice waters, from the formation of intermolecular O-H.....O hydrogen bonds, have been shown to self-assemble into an "acyclic water trimer" in the crystals of both 1 and 2. The title compounds have been synthesized in a simple one pot aqueous wet-synthesis consisting of aluminum/chromium chloride, sodium molybdate, copper nitrate, phenanthroline, and hydrochloric acid, and characterized by elemental analyses, EDAX, IR, diffuse reflectance, EPR, TGA, and single-crystal X-ray diffraction. Both compounds crystallize in the triclinic space group P. Crystal data for 1: a = 10.7618(6), b = 15.0238(8), c = 15.6648(8) angstroms, alpha = 65.4570(10), beta = 83.4420(10), gamma = 71.3230(10), V = 2182.1(2) angstroms3. Crystal data for 2: a = 10.8867(5), b = 15.2504(7), c = 15.7022(7) angstroms, alpha = 64.9850(10), beta = 83.0430(10), gamma = 71.1570(10), V = 2235.47(18) angstroms3. In the electronic reflectance spectra, compounds 1 and 2 exhibit a broad d-d band at approximately 700 nm, which is a considerable shift with respect to the value of 650-660 nm for a square-pyramidal [Cu(phen)2L] complex, indicating the coordination of [M(OH)6Mo6O18]3- POM anions (as a ligand) to the monophenanthroline copper complexes to form POM-supported copper complexes 1c, 1a, 2c, and 2a. The ESR spectrum of compound 1 shows a typical axial signal for a Cu2+ (d9) system, and that of compound 2, containing both chromium(III) and copper(II) ions, may reveal a zero-field-splitting of the central Cr3+ ion of the Anderson anion, [Cr(OH)6Mo6O18]3-, with an intense peak for the Cu2+ ion.
Aluminum Chloride↗