Chromium analytical method

Chromium compounds Cr203 surface scale Nickel- chromium—iron alloys Nickel-chromium— molybdenum (tungsten) alloys Ni-Cr alloys analytical methods, 6 502-514 composition of metal compared to chromium ferroalloys, 6 501t dispersoid former, 2 325, 327 disposal, 6 519-521 economic aspects, 6 496—500 effect on cobalt alloys, 7 220 effect on stainless steel corrosion resistance, 7 809... 

Chromium(II) chloride, 6 528t, 531, 564t Chromium(III) chloride, 6 532 physical properties, 6 528t Chromium(IV) chloride, 6 535 Chromium(III) chloride hexahydrate, physical properties, 6 528t Chromium chromate coatings, 76 219—220 Chromium complexes, 9 399 Chromium compounds, 6 526-571 analytical methods, 6 547-548 economic aspects, 6 543-546 environmental concerns, 6 550—551 health and safety factors, 6 548-550 hydrolysis, equilibrium, and complex formation constants, 6 530t manufacture, 6 538-543... 

An accurate determination of copper and zinc traces in human serum samples from the International Measurement Evaluation Programme-17 launched by IRMM (Geel) has been made by isotope dilution TIMS.38 An analytical method for the multi-element determination of metals (Ti, V, Cr, Co, Ni and Mo) potentially released from dental implants and prostheses into human body fluids (in blood and urine) by ICP-MS (double-focusing sector field instrument and quadrupole instrument with octopole collision cell) for medical studies was developed in Sanz-Medel s group.39 The Cr and Co concentrations found in blood samples of patients with chromium-cobalt based alloy varied in the sub-p,gl 1 range and were not significantly higher than the basal levels found by other authors.40... 

ISO 4621 (1986) also specifies analytical methods. Usually, analysis of chromium and the byproducts is preceded by melting with soda and sodium peroxide. The content of water-soluble or acid-soluble chromium is becoming important from the toxicological and ecological point of view. It is determined according to DIN 53 780 with water, or according to ISO 3856, part 1 with 0.1 mol/L hydrochloric acid. 

Copper, Chromium, Manganese, and Nickel. The analytical method for determining copper, chromium, manganese, and nickel involves digesting the coal with nitric and perchloric acids, fusing the residue with lithium metaborate, and determining the combined digestion and leach solutions by atomic absorption spectrophotometry. Since there is no standard material to analyze for the construction of calibration curves, the standard additions method is used for the assay. While this method increases the time required for analysis, it helps to eliminate the effect of the matrix. 

Difficulties have been observed in the preservation of samples for speciation of chromium. Chromium speciation in seawater was determined on board ship shortly after samples had been collected (Abollino et at., 1991). Some samples were frozen, and analysed later in a laboratory. However, significantly lower concentrations of Crvl were observed in these latter samples. Thus, sea-going analytical methods for the determination of Crm and total chromium are of particular importance (Mugo and Orians, 1993). The volatile trifluoroacetyl-acetone derivative of Crm was formed and then concentrated by extraction into toluene. Chromium was determined by means of a gas chromatograph equipped with an electron capture detector. Total chromium was determined as Cr111 after reduction. The detection limits were 0.062 and 0.255 nmol dm 3 total chromium. A useful method was described for sampling natural water in the field, and for the preservation of Crm and Crvl species for subsequent analyses in a laboratory (Cox and McLeod, 1992). Water samples were drawn through small columns packed with activated alumina, which had been prepared previously. Chromium species were retained on the columns. 

Total chromium and Cr in samples of stainless steel welding dusts were determined after extraction of the samples with a pH 4 buffer solution (Girard and Hubert, 1996). The analytical method involved the use of an FI system equipped with two detectors. The first detector (spectrophotometer) measured Crvl as the diphenylcarbazide complex. The second detector (AA spectrometer) measured total chromium. The recovery of chromium was 96%, and the lower detection limit was 0.005 mg ml-1. 

Analytical Methods for Determining Chromium in Biological Materials... 

The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring chromium, its metabolites, and other biomarkers of exposure and effect to chromium. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). 

Several methods are available for the analysis of chromium in different biological media. Some of the more recent methods for the determination of chromium are reported in Table 6-1. Several other reviews on the subject provide a more detailed description of the available analytical methods (EPA 1984a Fishbein 1984 IARC 1986a, 1990 Torgrimsen 1982 WHO 1988). 

Table 6-1. Analytical Methods for Determining Chromium in Biological Materials (continued) ... 

Kumpulainen J. 1984. Chromium. In Vercruysse A, ed. Techniques and instrumentation in analytical chemistry. Vol. 4 Evaluation of analytical methods in biological systems. Part B Hazardous metals in human toxicology. Amsterdam, The Netherlands Elsevier Science Publishers, 253-277. 

NIOSH. 1994c. Chromium and chromium compounds, as Cr. Method 7024. In NIOSH manual of analytical methods. 4th ed. Cincinnati, OH Department of Health and Human Services, National Institute of Occupational Safety and Health. DHHS publication no. 94-113. 

Sheehan P, Ricks R, Ripple S, Paustenbach D. 1992. Field evaluation of a sampling and analytical method for environmental levels of airborne hexavalent chromium. Am Ind Hyg Assoc J 53(l) 57-68. 

Chromium. Chromium is not an easily analyzed element because three distinct standards are listed by OSHA (Tables IV and V ). One standard exists for hexavalent chromium, chromic acid and chromates, another standard for soluble chromium compounds and chromous salts, and another standard for insoluble chromium compounds and chromium metal. The permissible amount of chromium in air decreases as the oxidation state increases. The analysis of chromium is further complicated by the multiplicity of NIOSH methods for chromium compounds. Hexavalent chromium shall be collected on PVC filters, although a criteria document for chromic acid (14) specifies mixed cellulose ester filters. The analytical method described in the hexavalent... 

The environmental scientist has at his disposal a variety of sensitive, multi-elemental analytical methods that can lead to a massive amount of data on airborne metals. Optimum use of these tools for environmental monitoring calls for focusing resources only on those metals that are environmentally important. Considerations of toxicity along with their ability to interact in the air, leading to the formation of secondary pollutants, and their presence in air have led to the identification of 17 environmentally important metals nickel, beryllium, cadmium, tin, antimony, lead, vanadium, mercury, selenium, arsenic, copper, iron, magnesium, manganese, titanium, chromium, and zinc. In addition to the airborne concentration, the particle size of environmentally important metals is perhaps the major consideration in assessing their importance. 

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