170135_inorganicventures_flipping

5:2 Container Material Properties

Porcelain:

• Porcelain is a popular material used for ashing purposes. • Porcelain contains Na, K, Al, and Si in increasing concentra:on. • It is typically coated with a glaze which is about 70 % SiO2, with roughly equal amounts of the oxides of Al and Ca, and lesser amounts of Na and K. • AHack will occur if the sample contains even minor amounts of the alkali metals. This is made evident by a dulling in the normally shiny surface. • If alkalis are present, then the sample is typically treated with conc. H2SO4 prior to ashing. • The following should not be heated in porcelain: HF; boiling H3PO4; and the oxides, hydroxides, or carbonates of the alkali or alkaline earth elements. • The major advantage or porcelain over glass is that it can be heated up to 1100 ̍C

5:3 Container Material Properties

Quartz:

• There are two types of quartz -- opaque and transparent. • Opaque quartz has the highest trace element concentra=on and should not be used for trace analysis. • Transparent quartz comes in four different varie=es; • Types I & II are made from naturally occurring quartz crystals or sands. Type I is created by electric mel=ng and type II by flame mel=ng. Type II has slightly less impuri=es than type I (some impuri=es are vola=lized by the flame). • Type III quartz is made synthe=cally by vapor phase hydrolysis of pure silicon compounds such as SiCl4. This type of quartz is more pure than the natural quartz, with the excep=on of Cl - which is ~ 50 ppm. • Type IV quartz is synthe=cally made from SiCl4 using a process involving electrical fusion of the oxidized staring material. It is as pure as type III, with respect to trace metal content, and contains far more Cl-.