Chromatography Forum

Hi,
I am currently doing method validation for a GC direct injection method. It worked fine for me as chemist 1 on an Agilent 6890 instrument. When the second chemist did intermediate precision on an Agilent 7890 instrument, he found that the recovery was too high (about 120%).

What's the possible reason for that? Does anybody have same situation? Any suggestion will be appreciated.

Could you please give some more information?
-Compound types and recoveries (are all too high or just one compound?)
-liner type
-are you using the same calibration method for both instruments or are they calibrated individually using the same method parameters?
-Oh yeah, what type of detector and what method is it for (is it a standard EPA type method?)

Did 2nd operator make up own standard, or did operator use an old standard which may have partially degraded, making concentration in samples high?

Did 2nd operator do something "simple", like use 200 ml volumetric flasks when procedure called for 250 ml VFs?

thanks for for the reply. The problem was solved. It was because the gold seal the 2nd chemist used was dirty and the a wrong liner was used. After changed goldseal and liner, it was fine.