Chromatography Forum

By dani andalas on Wednesday, August 11, 2004 - 09:48 pm:

Hello scientist, I have found difficulties how to determine LOD via GC chromatogram. Do I have to inject minimum concentration of standard

-----------------------------------------------------------------------------------
By carla on Sunday, August 15, 2004 - 02:40 pm:

ever tried a statistic software for calibration validation?

It kind of depends on how your company's SOP discussing this is written. As a rule of thumb Ive generally defined LOD as 3 times average noise value and try to get a the LOQ to no greater than 10 x the average noise value. Again, thats just MY OWN personal rule of thumb.
But hey, its an option you may want to consider.
~Law_son

Try using your lowest cal standard as your MDL (method detection limit)
Also, use 2-5 times below your RL (reporting limit). The signal to noise ratio mentioned earlier will work too.
Essentially you want to see how low your instrument can read with 99% confidence that it is > zero.

Semivoadude