Special purity

P.R.5 also lends itself to a variety of special applications. The list includes (decorative) cosmetics such as lipstick, eye shadow, powder, nail polish, and others. Application in this area depends on special purity requirements, and the commercially available types are tested accordingly. The pigment is listed in the European Cosmetics List. 

Commission Directive No. 95/31/EC laying down special purity criteria concerning sweeteners for use in foodstuffs, Official Journal of the European Communities 1995 L178 1-19 with subsequent amendments. 

The benzyl cyanide, prepared according to the procedure as outlined, is collected over a 50 range. It varies in appearance from a colorless to a straw-colored liquid and often develops appreciable color upon standing. For a product of special purity, it should be redistilled under diminished pressure and collected over a 1-20 range. For most purposes, such as the preparation of phenylacetic acid or ester, the fraction boiling i35-i40°/38 mm. is perfectly satisfactory. 

For a product of special purity, crystallization from benzene is advisable. For most purposes, however, the nitrobenzoic acid may be used without crystallization, since its melting point is found to be within 20 of the correct value of 238°. 

Purity criteria of colours for use in foodstuff are regulated in the EU under Directive 95/45/EC [4], According to the legislation food dyes that are placed on the market, must meet special purity requirements An example for C.I. Food Yellow 4 (tartrazine) is shown here ... 

A mercury-sulfate electrode served as a reference electrode. All electrode potentials are referred to the potential of the reversible hydrogen electrode in the same electrolyte and at the same temperature as the test electrode. Adsorption measurements were performed in the 0.5 M H2SO4 solution prepared using special purity B-5 sulfuric acid and water doubly-distilled. To remove oxygen dissolved in the electrolyte, pure helium or argon was bubbled through acid solution. 

For the VO2 thin films acquisition we have used a method of electron-beam evaporation of special purity metallic vanadium target with a consequent thermal oxidation in the atmosphere of N2, containing residual quantity of water vapors and oxygen. Single-crystal oxidized Si wafers 76 mm in diameter were used as substrates. 

Rectifyingx—When alcohol of special purity is required, it is further purified by special rectification. This is usually done by diluting the spirit with water to a strength of about 45 to 50 per cent., and redistilling it. Intermittent stills which fractionate the distillate (the impurities being in the first and last runnings), and continuous rectifying stills are used for the purpose. 

Butadiene. Phillips special purity butadiene (99.5 mole %) was distilled from the cylinder into a dry ice chilled 1700-cc bomb. This bomb was then inverted and connected to a 4 x 2" stainless steel column packed with 3A molecular sieves. (4A sieves cause polymerization 3A do not.) The liquid butadiene was passed through this column and metered out slowly (150 grams in 15 minutes) through a vernier needle valve connected to a syringe needle into the polymerization bottles. 

This chapter presents the state of the art of experimental equipment available for dynamic surface and interfacial tension measurements. The introductory section demonstrates the crucial importance of a special purity of surfactants and solvents, called surface-chemical purity, for interfacial studies. It turns out that studies of surfactant adsorption layers could be... 

PROPERTIES RESEARCH GRADE SPECIAL PURITY RUBBER GRADE... 

The above procedures are suitable for the purification of relatively large amounts of solvent (in the litre range). Preparative gas chromatography has proved the most suitable method for the preparation of small portions of solvents (50-500 mg) of special purity. However, the resulting extremely pure solvents are required only for the solution of special problems on the micro scale. 

In spite of the large quantities of sulfuric add offered, a weD-defined demand exists for add of special purity. This means low mercury acid with 0.1 ppmw Hg is at a premium (5 DM per tonne in 1994) over typical merchant-grade product, which has up to 0,5 ppmw mercury jll]. A specification for technical-grade sulfuric acid is given in Table 11.8. 

Phosphates added in food manufacture should, however, meet special purity standards as laid down, for example, in appropriate food regulations of Great Britain or the United States. Impurity limits should be... 

The Isothermal method was used. The The NaCl was of a special purity. Reagent ... 

A special purity grade of salts was used and the salts were recrystallized before being used. 

Air can be compressed at the point of use for most practical applications. To meet needs for air of special purity or specified composition (as in certain medical, scientific, industrial, fire protection, undersea, and aerospace uses), it is purified or compounded synthetically and shipped in cylinders or tube trailers as a nonliq-uefied gas at high pressures. 

Irrespective of the purification carried out, it is essential for maintaining the quality of the raw material to ensure suitable pretreatment of the containers and adequate gas transfer in the filling station. These topics are being referred to in Sections 9.3.2.2 and 9.6. The supply of special purities is also possible on the basis of analytical control ( selection procedure ). 

The sample was purchased on the market as o-toluidine of special purity. 

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