METHOD DETECTION LIMIT

[chemjeeorganic]

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

[Don_Hilton]

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?

[gpronger]

Chemjeeorganic;

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

Thanks,

Greg

[randy]

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

[chemjeeorganic]

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

[gpronger]

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

[chemjeeorganic]

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