Colorimetric Determination of Copper in Aluminum Alloys

Abstract

tion to a ground-glass stoppered bottle of soft glass (boron-free glassware is preferable, if available).After one hour, the solution may be compared visually to a series of sealed standards which can remain stable indefinitely. The photoelectric colorimeter may be employed as an alternate means of estimation. The instrument is adjusted to zero with concentrated sulfuric acid in the cell and readings are taken on all solutions, including a blank determination on boron-free steel which is run simultaneously. A No. 60 filter is used. The blank reading obtained is subtracted from the sample reading. The per cent of boron is then determined by referring to a curve previously drawn from a series of standards of increasing boron content.The standards are prepared from samples of boron-free steel, to which increments of standard boric acid solution equivalent to 0.001% boron are added. (Steel samples must be used in preparing the standards, as there is a proportionate retention of boron in the hydroxide precipitate.) A blank is carried along and deducted in the usual xvay.

Investigation of the dynamics of an elastin‐mimetic polypeptide using solid‐state NMR

“…5 Water is known to play an extremely important role in elastin function, since only water-swollen elastin exhibits elasticity. 6,7 Therefore, to elucidate the molecular basis for elastin elasticity, it is crucial to examine the interaction between the protein and the water.…”

Determination of Trace Impurities in High-Purity Magnesium and Calcium

“…Although the manganese content of magnesium alloys is much higher than that of pure calcium, the large amount of citrate u<ed in former case tends to prevent manganese interference (10).…”

“…When this was applied to alloys, a turbidity appeared, apparently due ;o the action of zinc. When ammonia was added in an attempt to eliminate this interference (10), magnesium hydroxide precipitated. Sandell's extraction procedure with carbon tetrachloride (15) was then attempted, and satisfactory results were ' 'brained.…”