170135_inorganicventures_flipping

10:10 Contamination from the Analyst and Apparatus

Contamina(on from the apparatus: Figure 10.2 demonstrates how quartz is the cleanest of all sample container materials that can withstand typical ashing temperatures (T > 400 ̍C).

Increasing Impuri(es

Figure 10.2: Container Materials in order of Increasing Impurites Increasing Impuri(es

Polyethylene - Low density (free radical iniIated) Fluorocarbons - (i.e. - Teflon, Tefzel, Halar, Kel-F) Quartz - SyntheIc Polyethylene - High density Quartz - Natural PlaInum Borosilicate

10:11 Contamina(on from the Analyst and Apparatus

Contamina(on from the apparatus: Tips

§ Avoid filtra,on due to contamina,on from the filter paper. It is far be9er to centrifuge the sample using polyethylene tubes (acid- leached). § If filtra,on is necessary, use Teflon filters as your first preference. These are followed by cellulose acetate, polypropylene, or polycarbonate filters that have been acid-leached. § Avoid rubber stoppers and all tubing except that made from Teflon or polyethylene. § For grinding, use apparatus made from quartz, tungsten carbide, or pure molybdenum since they introduce significant contamina,on of only a single element (the tungsten carbide does introduce some cobalt).