Chromatography Forum

Hi

I want to determine the MDL for PAH anlysis. I prepared 10 ppb standard. i am using a split injection (10:1). I wants to know whether can i concentrate this standard to 1ml and do the injection to do MDL.

Thanks
JN

Personally, I would avoid concentration steps in making standards. If your PAH standard is too dilute, what about the idea of running splitless, which will give you a lower LOD?

Chemjeeorganic;

Could you give some more details on your purpose for the "MDL" and the whole analysis?

Thanks,

Greg

I would think that a 10ppb standard could easily be detected, and that dilution and not concentration would be the way to go.

Hi Randy

Do you mean you can detect 10 ppb by SIR?. If so can you let me know how to achive it?

Thanks
NJ

Chemjeeorganic,

We perform a fair number of analyses by GCMS using SIM. We run in the splitless mode, and calibrate from 10PPB to 1000PPB injected concentrations. This gives a somewhat quadratic fit, but our sample concentrations tend to be fairly wide ranging, so we find it more efficient to run more calibration points (this is an 8 point calibration) to avoid dilutions. The instruments are an Agilent 5972 and an Agilent 5973. We have just begun evaluating our Thermo DSQ-2 for this application, and are able to calibrate to 0.5 ug/L (again in SIM).

Sincerely,

Greg Pronger

Hi Greg,

This was the information i was looking for. Already i have developed SIM method for SVOC analysis. But i was not sure whether to do spilt or splitless injection. Let me try i will let you know

Thanks

jn