170135_inorganicventures_flipping

14.8 Ashing

Ashing Techniques: Avoiding common problems

• If the sample type is unknown (with respect to the matrix) then a % ash, EDXRF scan, IR scan, and C, H, and N analysis will provide sufficient informaHon in most cases to make informed decisions. • Protect your Pt̍ ware by looking for P (high levels will aLack and aLach to the Pt̍) and elements that alloy with Pt̍ which include the precious metals, Cu, and Hg. • When using 'silica' containing crucibles (porcelain, Vycor, quartz, glass, and fused silica) look for elements that form basic oxides such as the alkali earth elements. Na is commonly found and it's oxide will form (unless the char is sulfated) and aLack the silica

14.9 Ashing

Ashing Techniques: Avoiding common problems

• Look for vola5le elements (Cd, B, Hg, Pb, Se, Zn, As, Sn, Sb, S, and halogens) especially if moderate to large amounts of F or Cl are present. • Si is a common element that is typically determined by dissolu5on of an ash performed in Pt̍. Methyl silicones are widely used and very common. If Si is present as a silicone oil then it will be as an ashing aid will help prevent losses of 'low density' ashes, and will help in preven5ng reten5on losses. par5ally lost as the hexamethycyclotrisiloxane and the hexamethydisiloxane. • Reten5on and physical loss of analyte(s). The use of high purity Mg(NO 3 ) 2