[kamiyu]

This is my first time to submit sample for elemental analysis. Two questions:

1) How much sample is needed? 10mg OK??

2) Is the result significantly affected by trace amount of solvent?

[Arkcon]

This isn't enough information.  What elements will be tested for, and by what method?

[kamiyu]

1) For C, H and N

2) I have no idea for method being used. I just prepare sample to be submitted.

[Arkcon]

So you're submitting an organic compound, presumably one you've made, for CHN analysis.  Presumably by combustion analysis.  http://en.wikipedia.org/wiki/Combustion_analysis  You will want it as pure as possible, given they will probably only use 1-2 mg of your compound.  So yes, you should try to remove as much solvent, by evaporation, if possible.  You should probably ask where you're sending the sample what their needs are.  However, this resource may have some guidelines.  http://www.rsc.org/images/CHNS-elemental-analysers-technical-brief-29_tcm18-214833.pdf