Hi all,

I need your help one more time. I have a problem in spike recovery of napthalene-d10. I am using 4 internal standards benzene-d6, toulene-d8, ethylbenzene-d10 and naphthalene-d8 and my solvent is carbon disulphide. When I spike internal standards in neat carbon disulphide solvent (which is a calibration standard) I am good response for all the four ISTDs.

But when I spike ISTDs in charcoal treated Carbon disulphide solvent (which is a sample) I am not getting good response for Naphthalen-d8 (other three ISTDs response are good with out supression and similar to Cal std). Less response in spiked sample is for Naphthalene-d8 only which is the high mass Compound. Is this a high mass discrimination? or something different (like a matrix effect/supression?). How can I resolve this issue and get good response for Napthalene-d10 similar to cal standard. Currently I am getting only 25% recovery for Naphthalene in charcoal treated CS2 sample. I am using Agilent 6890N GC with 5973N Mass Spec. Can some one give me some suggestions? Is this injection related? Please give me some suggestions.

Thank you,
Srikanth.S