Ray Carlton on fri 11 dec 98
At 13:41 10/12/98 EST, you wrote:
>----------------------------Original message----------------------------
>At 09:52 AM 12/10/98 EST, you wrote:
>>----------------------------Original message----------------------------
>>Hello everybody,
>>
>>When looking the molecular formulas and percentage alnaysis of many
>>ceramic materials in the Ceramics Web Materials Database, I found a
>>percentage given for something called "L.O.I.". Does anybody know what
>>that stands for? I think it may be the same as "I.L." on the Clay and
>>Feldspar Analysis Charts in Chappell's book, but I'm not sure.
>
>LOI = Loss On Ignition
>IL = Ignition Loss
>
>Both terms mean that mass of the material which became volatile and escaped
>the analysis. This is principally water, sulphur and carbon in various
>forms, but may also include halides (Cl, Fl, Br, etc.), noble gasses (He,
>Ne, Ar, etc), other non-metals (O, N), and to some degree the more volatile
>metals, such as lead. Most potter's analyses are intended to show the
>metals and metalloid (plus phosphorus) content, reported as oxides of a
>particular degree or oxidation (e.g., iron as Fe2O3 or FeO2). Most of the
>volatiles are therefore not of interest, and the LOI or IL figure is useful
>simply to tell how much extra material must be used in order to obtain the
>analysis quantities of the oxides, as in preparing a recipe.
>
>However, any loss of metals is a fault in the analysis, and much of the
>skill in analysis comes in the form of sample preparation technique so as
>to preserve the metallic content of the sample while ashing and separating
>it from the volatiles. In the case of spectroscopic analysis as a flame
>spectrum, the quantity of material present is measured by comparing the
>brightness of a particuar spectral line, chosen for its particularity to a
>single ionic form of the metal in question, and for its intensity relative
>to other nearby lines, to that obtained from a sample of known
>concentration. The accuracy of the result depends on many things, but
>directly on the sample preparation technique.
>
>In the case of an analysis for a volatile metal, like lead, particular care
>must be taken to preserve that metal from volatilization, or loss from the
>sample during preparations. Ashing is therefore usually done by acid
>digestion, and no high temperature steps are used. Acids used in this step
>are composed only of volatile elements, so the metal concentration
>information can be preserved throughout the preparation.
>
>Gavin
>
>Gavin Stairs
>Stairs Small Systems (S3)
>921 College St., # 1-A
>Toronto, Ontario, Canada M6H 1A1
>(416)530-0419 stairs@stairs.on.ca
>
cheers Ray Carlton
McMahons Creek Victoria Australia
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