• Replies 3 replies
  • Subscribers 8 subscribers
  • Views 788 views
  • Users 0 members are here
Related

Agilent Knowledge Portal

Find maintenance, best practice, and troubleshooting articles.

Agilent Knowledge Portal

Issues with 525.2 surrogates

bigbear

I've been doing 525.2 for close to 16 years, and lately been having issues with perylene d 12, and triphenyl phosphate failing the +/- 30% of targeted concentration. I don't think the issue is due to my sample concentration step, as the nitro xylene recovers very well. The triphenyl phosphate sometimes recover over 130% and the perylene d 12< 70%.

 

With what I see it may be due to the way I handle my surrogate mix. The mix is a commercial 3 component mix @ 500ppm in acetone.Manufacturer's storage requirements are ambient temp. I store it in a freezer that is usually about -15C. Prior to use I warm it and then vortex.

 

My theory is that the perylene d12 falls out of solution in the freezer and warming and mixing is not enough. the other week I prepared a continung calibration std. using the mix of compounds used to spike my LFM/Bs. I combined this mix, the IS and surrogates and brought to volume. When I ran it against the initial calibration everything was very much in range with the exception of the perylene d12, which recovered in the mid 70%. I see similar results using the con cal prepared with the initial calibration.

 

The implication is that I am not completely reconstituting the perylene d12.

 

Any thoughts?

  • Hi Bigbear,

    I have experience with enviromental samples and IS/SS problems.  Have to found a cause and fix to your problem ?

    We have never experienced loss of late eluting IS/SS due to freezer storage, but have not performed a detailed study comparing to refrigeration or ambient.  We have tracked losses due to liner configuration change, inlet parameter changes, mass spec parameter changes, mass spec source type and lens configuration.  We also had IS/SS late eluter problem due to new "defective" standard from supplier.  Happy to share more details if needed.

    Thanks,

    Trifecta

  • Is your method a split method? Reason being is that we have seen particularly high boilers being affected in split due to two things, sample discrimination and full split vent lines (not traps but the copper lines from the inlet to the trap).

    So in split injections the heavier less volatile/slow moving molecules get split more readily than hitting the column, but any disruption from the split vent line/trap can cause differences in partial pressures in the inlet change the irection of analyte flow onto the column. 

  • in reply to gchaplai

    Thanks. I thought I posted the results of my "fix". I found that if I warm the extracts from the freezer for a while, then sonicate them for 5-20 min, then vortex I have no problem.

     And  chapain, I use a pulsed splitless injection (50psi for 0.49 min)  a direct connect liner with the hole at the top.

Was this helpful?
Privacy Statement
Terms of Use
Contact Us
Site Help