Applications cobalt blues

Cobalt blue (pigment blue 28 and pigment blue 36) occupies several niches in plastics applications. It is a viable alternative to phthalocyanine blue in high-density... 

Contact Lens Fitting and Management Fluorescein staining of the tear film is a major aid in the fitting of rigid gas-permeable contact lenses.After topical application of fluorescein to the eye the tear layer becomes visible, with a characteristic pattern of green fluorescence. Observation of the fluorescein-stained tear film with an ultraviolet light or the cobalt blue filter of the slit lamp allows determination of the fit of the lens. 

Electrocatalysis in oxidation has apparently first been shown for ascorbic acid oxidation by Prussian blue [60] and later by nickel hexacyanoferrate [61]. More valuable for analytical applications was the discovery in the early 1990s of the oxidation of sulfite [62] and thiosulfate [18, 63] at nickel [62, 63] and also ferric, indium, and cobalt [18] hexacyanoferrates. More recently electrocatalytic activity in thiosulfate oxidation was shown also for zinc [23] hexacyanoferrate. Prussian blue-modified electrodes allowed sulfite determination in wine products [64], which is important for the wine industry. 

A particular interest for clinical applications was a possibility for detection of dopamine by its oxidation on nickel [19], cobalt [65], and osmium [66] hexacyanofer-ates. Except for oxidation of dopamine, cobalt and osmium hexacyanoferrates were active in oxidation of epinephrine and norepinephrine. For clinical analysis it is also important to carry out the detection of morphine on cobalt [67] and ferric [68] hexacyanoferrates, as well as the detection of oxidizable amino acids (cystein, methionine) by manganous [69] and ruthenium [70] hexacyanoferrate-modified electrodes. In general, oxidation of thiols was first shown for Prussian blue [71] and nickel hexacyanoferrate [72], This approach has been used for the detection of thiols in rat striatum microdialysate [73], Alternatively, the detection of thiocholine with Prussian blue was employed for pesticide determination in acetylcholine-esterase test [74],... 

A. Malinauskas, R. Araminaite, G. Mickeviciute and R. Garjonyte, Evaluation of operational stability of Prussian blue and cobalt hexacyanofer-rate-based amperometric hydrogen peroxide sensors for biosensing application, Mater. Sci. Eng. C, 24 (2004) 513-519. 

Regulated Colorants That Are FDA Approved. It often seems a contradiction that many of the colorants that are suitable for use in food contact applications must also appear on an MSDS as a reportable or hazardous material. Examples include zinc oxide and zinc sulfide, both zinc compounds chromium oxide green (pigment green 17), a chromium compound carbon black and cobalt aluminate blue (pigment blue 28), which is not only reportable because of its cobalt content but is also a suspected carcinogen. 

Pure nickel was first isolated in 1751. Like cobalt, nickel was used to color glass, though nickel compounds turn glass and other substances green rather than blue. Because nickel is resistant to corrosion, it is often combined with other metals to form alloys that resist oxidation. A process known as electroplating uses nickel to coat the surface of metals that are vulnerable to corrosion, like iron or steel. Stainless steel is an example of a product made from nickel almost half the nickel that is mined each year is used to manufacture it. Also composed of chromium, stainless steel is extremely resistant to corrosion. Another nickel alloy is monel, which is made with copper. Monel is hard and resistant to corrosion, making it ideal for commercial marine applications such as the manufacture of boat propellers. The heating parts in toasters and electric ovens are made from an alloy called nichrome, which is another metal, made from chromium and nickel. 

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