Plasma chromium

The distribution of chromium(III) in humans was analyzed using a whole-body scintillation scanner, whole-body counter, and plasma counting. Six individuals given an intravenous injection of 51chromium(III) as chromium trichloride had >50% of the blood plasma chromium(ni) distributed to various body organs within hours of administration. The liver and spleen contained the highest levels. After 3 months, the liver contained half of the total body burden of chromium. The study results indicated a three-compartment model for whole-body accumulation and clearance of chromium(III). The half-lives were 0.5-12 hours for the fast component, 1-14 days for the medium component, and 3-12 months for the slow component (Lim et al. 1983). 

A 33-year-old white woman presented with weight loss, anemia, thrombocytopenia, hemolysis, liver dysfunction (transaminase activities 15-20 times normal, total bilirubin three times normal), and renal insufficiency. She had taken chromium picolinate 1200-2400 micrograms/day for the previous 4-5 months to enhance weight loss. Her plasma chromium concentrations were 2-3 times normal. After withdrawal of chromium picohnate, she was managed with supportive measures, blood transfusions, and hemodialysis. The hemolysis stabilized and her liver and renal function eventually recovered. 

IGtapci F, Dilmen U, Akyol O, Toppare M> Kaya IS, Senses DA, et al. Plasma chromium levels in hypoglycemic preterm, full-term and in intrauterine-growth-retarded babies. Biol Neonate 1994 66 ... 

Hambidge, 1972). A glucose load leads to a rise in plasma chromium, and much of this chromium may then be lost in the urine. It is possible, therefore, that the large amounts of glucose infused during total parenteral alimentation may result in an increased requirement for chromium. 

In Table 2, a comparison is made of the red cell plasma chromium ratio in rats given soluble Cr(VI) by three different routes of administration. The fraction of absorbed chromium entering the systemic circulation as Cr(VI) declines in the order intravenous > intestinal > oral administration. If... 

Table 2. Red cell plasma chromium after administration of Cr(VI) salts...

Cr(VI) enters the red cell rapidly while Cr(III) does not, the red cell. plasma chromium ratio at any single time point after administration should decline in the same order. As Table 2 shows, this is in fact the case. In addition. Table 2 shows that the red cell plasma chromium ratio increases with time after administration, and suggests that the fraction of an intratracheal dose of Cr(VI) entering the systemic circulation as Cr(VI) may fall between the values for fractional absorption from intravenous and intestinal doses. 

After intratracheal administration of a radiolabeled soluble Cr(VI) salt to rats, Weber (1983) found that the amount of radiolabel in the serum was greater than that in the red cells at 6h after administration, but that by 2 days after administration the serum contained only 40% as much chromium as the red cells. By 40 days after administration, the percentage had declined to 1.0. Therefore, red cell chromium is lost more slowly than plasma chromium, and plasma chromium is the pool from which chromium is transferred into other tissues and from which it is excreted. 

Figure 3 Picture of the inspected part (plasma-sprayed chromium cast iron on ferritic steel). The surface presents several cracks I to 15 pm wide.

The classical wet-chemical quaUtative identification of chromium is accompHshed by the intense red-violet color that develops when aqueous Cr(VI) reacts with (5)-diphenylcarba2ide under acidic conditions (95). This test is sensitive to 0.003 ppm Cr, and the reagent is also useful for quantitative analysis of trace quantities of Cr (96). Instmmental quaUtative identification is possible using inductively coupled argon plasma—atomic emission spectroscopy... 

Instrumental Quantitative Analysis. Methods such as x-ray spectroscopy, oaes, and naa do not necessarily require pretreatment of samples to soluble forms. Only reUable and verified standards are needed. Other instmmental methods that can be used to determine a wide range of chromium concentrations are atomic absorption spectroscopy (aas), flame photometry, icap-aes, and direct current plasma—atomic emission spectroscopy (dcp-aes). These methods caimot distinguish the oxidation states of chromium, and speciation at trace levels usually requires a previous wet-chemical separation. However, the instmmental methods are preferred over (3)-diphenylcarbazide for trace chromium concentrations, because of the difficulty of oxidizing very small quantities of Cr(III). 

The second approach, that of surface coating, is more difficult, and that means more expensive. But it is often worth it. Hard, corrosion resistant layers of alloys rich in tungsten, cobalt, chromium or nickel can be sprayed onto surfaces, but a refinishing process is almost always necessary to restore the dimensional tolerances. Hard ceramic coatings such as AbO, Cr203, TiC, or TiN can be deposited by plasma methods and these not only give wear resistance but resistance to oxidation and... 

Samples Analyzed by Inductively Coupled Plasma (ICP) Metals — Where two or more of the following analytes are requested on the same filter, an ICP analysis may be conducted. However, the Industrial Hygienist should specify the metals of interest in the event samples cannot be analyzed by the ICP method. A computer print-out of the following 13 analytes may be typically reported Antimony, Beryllium, Cadmium, Chromium, Cobalt, Copper, Iron, Lead, Manganese, Molybdenum, Nickel, Vanadium, Zinc. Arsenic — Lead, cadmium, copper, and iron can be analyzed on the same filter with arsenic. 

Figure 12-8A. Piston rings. The piston rod is manufactured from heat-treated stainless steel and is coated with wear-resistant overlays, such as ceramic, chromium oxide, and tungsten carbide applied by plasma techniques. Piston rod cross-head attachment has mechanical preloading system for the threads. Rider rings and seal rings are manufactured from PTFE filled resins fillers are matched to the gas, piston speed, and liner specifications. Typical fillers are glass, carbon, coke, or ceramic. (Used by permission Bui. BCNA-3P100. Howden Process Compressors Incorporated. All rights reserved.)...

While plasma deposits are widely used, especially in the American aero industry to provide wear resistance, there is not at the moment any great demand for the exotic materials deposited to be used as a protection against corrosion. However, M. A. Levinstein of General Electric (USA) reports the successful use of sprayed chromium carbide as a protection for ventilator blades operating in corrosive conditions. 

The TFTs are made on transparent glass substrates, onto which gate electrodes are patterned. Typically, the gate electrode is made of chromium. This substrate is introduced in a PECVD reactor, in which silane and ammonia are used for plasma deposition of SiN as the gate material. After subsequent deposition of the a-Si H active layer and the heavily doped n-type a-Si H for the contacts, the devices are taken out of the reactor. Cr contacts are evaporated on top of the structure. The transistor channel is then defined by etching away the top metal and n-type a-Si H. Special care must be taken in that the etchant used for the n-type a-Si H also etches the intrinsic a-Si H. Finally the top passivation SiN, is deposited in a separate run. This passivation layer is needed to protect the TFT during additional processing steps. 

Area under the plasma concentration-time profile Chromium-51-labeled ethylenediamine-tetraacetic acid Cytochrome P450, 3A4 isozyme... 

Parts per billion concentrations of chromium (III) and chromium (VI) in seawater have been determined using high-performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry [196]. 

The application of the Spectroscan DC plasma emission spectrometer confirmed that for the determination of cadmium, chromium, copper, lead, nickel, and zinc in seawater the method was not sufficiently sensitive, as its detection limits just approach the levels found in seawater [731]. High concentrations of calcium and magnesium increased both the background and elemental line emission intensities. 

The preparation of film electrodes Prussian blue films are usually prepared by cycling an electrode in a freshly prepared solution containing iron(III) and hexacyanoferrate(III) ions [70-72]. As substrate, mostly platinum is used, sometimes glassy carbon [73] is used, and very frequently ITO electrodes [74] are used because the latter are very useful for electrochromism studies. Similar procedures using solutions containing metal ions and hexacyanoferrate(III) have been used to deposit cobalt hexacyanoferrate [75] and chromium hexacyanoferrate [76, 77]. Crumbliss et al. reported a plasma deposition of iron species from a plasma containing iron pentacarbonyl and ethane, followed by electrochemical derivatization of the deposited iron sites with the help of hexacyanoferrate solutions [78]. 

The resist has been used as a mask in wet etching and in lift-off processes, and more recently in etching chromium films in a chlorine-oxygen-helium plasma. In the latter, the etch rates have ranged from 4 to 5.5nm/min at lOOW power in a barrel type reactor. Chromium etches at about 6.5nm/min under these conditions. The etch rate of the resist appears to be independent of the degree to which it has been cured before exposure, so the sensitive form described here is just as effective a mask as the highly cross-linked resists described earlier, at least in the chromium etching process. 

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