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Effect of aqua regia on P, S, C and Si?

  1. Nov 22, 2007 #1
    I've got a sample containing 8 substances: P, S, C and Si (+4 metals) wich i need to analyse. I was planning on using aqua regia to dissolve the metals, remove the 4 substances that aren't metals (and deal with them later ^^) and then use atomic absorbtion spectroscopy to measure the metals' levels but I was wondering if the royal water would have any effect on any of the P, S, C or Si that are also in the sample?

    At first glance I would say it would have no effect, but I've never worked with agua regia before and it seems to be a rather peculiar mixture :). Anyone have any experience with this?
  2. jcsd
  3. Nov 22, 2007 #2


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    In what form are these? Are you actually given red/white/black phosphorus? Is it a phosphate? Is it part of something organic?
    Is this part of a powder, or is the sample a solution with sediment on the bottom?
  4. Nov 22, 2007 #3


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    The OP's sample may just be an alloy. AAS will give you concentrations for non-metallic components too.
  5. Nov 23, 2007 #4
    The sample is a powder and the P, S, Si and C are present in their 'elemental form' (not sure about the english word... but I mean that they're not bonded with another element).

    I also have some rough amounts btw:

    Si: 0 < x < 1g
    S: 0 < x < 0.1g
    P: 0 < x < 0.1g
    Mn: 0 < x < 1g
    Ni: 0 < x < 0.1g
    Cr: 0 < x < 1g
    Cu: 0 < x < 1g
    C: 1-2% of total sample

    But i should be able to detect the non-metallic compounds as well? I thought this technique only worked for metals in solution. I was assuming the non-metallic compounds wouldn't dissolve either.
    Last edited: Nov 23, 2007
  6. Nov 23, 2007 #5


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    Usually treatment with aqua regia involves boiling the sample to near dryness. Nothing but the silica should resist that treatment. The P will be oxidized to orthophosphate. The S will be oxidized to sulfate (if it isn't already sulfate) but not before it is oxidized to sulfite (which is volatile and will be lost). Carbon will be lost as CO2. Silica will remain in solid form. To analyze the non-metals (perhaps with the exception of P), you will need to withold some of the original sample and analyze it by different methods.
  7. Nov 23, 2007 #6
    thank you for your assistence, much appreciated :)
  8. Nov 23, 2007 #7
    Exactly; the OP was talking also about Silicium and that's attacked too (and forms silica).
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