Preparation of High Purity Metals and Assesment of Their Purity.

Preparation of Sulfur of High Purity

A mc thod is described for producing sulfur thaL conLains Ie. Lhan 1.3 X lO5 m ole [racLion of li q uid-solu ble, solid-insolubl e impuriLies as dcLermin ed by Lh e fr'eezing point depression . This corr e ponds t.o a purity of 99.999 mole p ercen t . Man y of Lhe impurities, including organic maLLcl', a r(' re moved by o,(ldaLion with s ulfuric and nitric ac ids. The nonvo lati le impuri ties ...

Preparation of High Purity Mullite Ceramics

Recovery of high purity precious metals from printed circuit boards.

Waste printed circuit boards (WPCB) have an inherent value because of the precious metal content. For an effective recycling of WPCB, it is essential to recover the precious metals. This paper reports a promising method to recover the precious metals. Aqua regia was used as a leachant and the ratio between metals and leachant was fixed at 1/20 (g/ml). Silver is relatively stable so the amount o...

High-purity preparation of a large DNA dumbbell.

We report on the efficient biochemical synthesis of a large DNA dumbbell starting from a pair of short DNA hairpins with long single-stranded tails of arbitrary sequence. The DNA dumbbell is obtained by enzymatic ligation yielding a 94-bp duplex stem closed at both termini by single-stranded loops of 5 nt. Following ligation, all unligated precursors and monoligated by-products were multiply bi...

Laboratory for preparation of high-purity clinical chemicals.

A laboratory is described for the preparation and analysis of high-purity clinical chemicals. The work area is designed to minimize contact of high-purity materials with the main source of contamination, the chemical operator. We discuss the use of a perforated, curved, anodized aluminum membrane that permits completely free access to the work area and describe the general construction of the l...