errors in icp?

[rookieminer]

I pulled out an icp I had done about a year ago on an ore from my claim. I was using it to calculate a fire assay flux formula for the ore, using the amounts of impurities present.
I hadn't looked it over for some time, and at the time I got it to see if there were any other valueable metals worth extracting. The ore has a lot of pyrite, among other sulfides, wich is evedent by the relatively high iron content. The part that doesn't make sense to me is that it also shows only trace amounts of sulfur.
Is it possible to have an error in an icp like that? I've done a chemical test on the ore, that confirms that no telurium is present, to rule out the possability of it being a telluride instead of sulfide.


rookieminer

 

[fireguy]

ICP has good points and bad. They are often used as a low cost method to determine a large number of elements, which works well for soil samples and as a screening technique. However, be careful when using this as quantitative result for any single element or on complex samples.

If you see a result that is interesting, do a single element assay on that element to verify the result.

ICP can be prone to inter-element interference. Iron is a bad offender, so samples high in iron will potentially cause problems.

Sulfur is not a particularly good ICP element, so depending on who is doing the assay and the particulars I would not put a great deal of stock in those results.

 

[pcorona]

low level sulfur can be a pain, though for a lotta years we estimated S in copper cathode in the 10-20 ppm range- that was a royal pain and do not recommend it. I determine sulfate (as sulfur) in water on a routine basis with rock steady results using 50 and 100 ug/L standards.