Certified aluminum

The FD C certified colors are all water-soluble dyes, but can be transformed into insoluble pigments known as lakes by precipitating the dyes with alurninum, calcium, or magnesium salts on a substrate of aluminum hydroxide. The lakes are useful in appHcations that require color whereas in dry form, such as cake mixes, or where water may be present and bleeding is a problem, such as food packaging. FD C Red Lake No. 3 was deHsted in Febmary... 

FD C lakes were first approved for use ia 1959. Today, they are the most widely used type of lake. To make a lake, an alumina substrate is first prepared by adding sodium carbonate or sodium hydroxide to a solution of aluminum sulfate. Next, a solution of certified colorant is added to the resulting slurry, then aluminum chloride is added to convert the colorant to an aluminum salt, which then adsorbs onto the surface of the alumina. The slurry is then filtered, and the cake is washed, dried, and ground to an appropriate fineness, typically 0.1—4.0 p.m. 

The terms FD C, D C, and External D C (Ext. D C), which are part of the name of colorants, reflect the FDA s colorant certification. FD C dyes may be used for foods, dmgs, and cosmetics D C dyes are allowed in dmgs and cosmetics and Ext. D C dyes are permitted only in topical products. Straight colorants include both the organic dyes and corresponding lakes, made by extending the colorant on a substrate such as aluminum hydroxide or barium sulfate. The pure dye content of these lakes varies from 2 to 80% the organic dyes contain over 80% pure dye. Colorants certified for cosmetic use may not contain more than 0.002% of lead, not more than 0.0002% of arsenic, and not more than 0.003% of heavy metals other than lead and arsenic. 

The only element whose concentration is recommended to be certified is iron. An iron reference material will also clearly be useful for studying other important metals such as zinc, manganese, copper, molybdenum, cobalt, vanadium, lead, aluminum, cadmium, and the rare earth elements. It is thus desirable to assure stability for some of these elements in addition to iron. 

Adequate digestion methods are important in the determination of all metals, including aluminum. Que Hee and Boyle (1988) showed that Parr bomb digestions were always superior to hot plate digestions for many elements, including aluminum, in feces, liver, and testes. Microwaving in closed vessels produced lower aluminum recoveries in liver than Parr bomb digestions. The Parr bomb values for citrus leaves were within 5% of the NBS certified values. 

In determining the hydrogen content in solid probes of titanium, copper and magnesium alloys and in steels, two express-methods are widely used, namely, the spectral method and method of melting in the flux of inert gas carrier. These fast methods require regular (by one shift of even one hour) calibration on the hydrogen content standards - State Standard Probes (SSP). In the SSP passport, the certified concentration of hydrogen in the probe and the allowed deviation with 95% confidence is indicated. For aluminum alloys, the relative value of the allowed deviation varies from 5 to 30%. 

It is worth mentioning that certified reference data were not available for the elements aluminum, titanium, vanadium, boron, nickel, and phosphorus at the time of analysis. This is a frequent problem in multielement analyses. It is diflBcult to obtain standard biological reference materials similar to the samples being analyzed with more than but a few certified analytical results. The lack of standard reference material limits quality assurance review of the data and diagnosis of analytical problems. The recent issue of new standards such as spinach leaves and brewers yeast will improve the material variety. Certification of more elements in the existing standards will also greatly assist the analyst. 

Fig. 2. Certified values of thermal expansion coefficients for SRMs 731, 736, 737, and 739, along with tentative values for stainless steel, graphite, sapphire, and aluminum.

In addition to these defining and secondary temperature standards, a thermocouple wire (SRM 733, a silver-28 at.% gold alloy) has been certified, which serves to compare manufactured wire to standard reference thermocouple tables between 4 and 273 K. SRM 767, a superconductive thermometric fixed-point device, provides temperature calibration in the range 0.5 to 7.2 K This device incorporates five high-purity elements (lead, indium, aluminum, zinc, and cadmium) in long, thin cylinders whose superconductive transition temperatures are certified to be reproducible within 1 mK. 

Synonyms Alum carmine Aluminum calcium lake Alum lake Alum lake of carminic acid Carmine Carmine alum lake Carmine, certified Carmine extract Carmine, high purity biological slain Cl 75470 Cochineal extract B Rose Liq. 

Calibration of TA instrumentation and development of standards for calibration continue to be administered by ICTAC in conjunction with ASTM. The standardization Committee of ICTAC has certified a range of materials for temperature calibration of TA systems, and in addition, standards for calibration of mass (known as Class M Standards ) are available for this purpose. A range of certified reference materials are available for enthalpy calibration in DSC. Temperature calibration for TMA and dynamic mechanical analysis (DMA) is effected by using disks of pure metals (silver, aluminum, and tin) separated by alumina disks. Load or force calibration for DMA is a complex process involving the use of calibrated weights. Temperature calibration for DETA is effected by measuring the melting transition of benzoic acid and dielectric calibration is... 

Manufacture of the food lakes requires the precipitation of food-certified dyes onto the surface of aluminum hydrate. The water of hydration present is to some extent driven off during incorporation into the plastic. Vented equipment is recommended. Over 90% of their use in plastics is in olefins for food-packaging applications. The colors available are FD C Red 40 (34), FD C Blue 1 (35), FD C Yellow 5, and FD C Yellow 6 (36). 

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