Chromatography Forum

Hi!
Regarding Internal standards for VOC (method 8260). The each individual target should be recalculated against IS only if its RRT value is 0.8-1.2.
I run the Drinking water standard mixture according to their recommended method and figured out, that several of Targets have RRT less than 0.8 (such Carbon Di-sulfide, Diethyl ether and etc).
How to recalculate them?

Those guidlines are sensible in general, but I believe they are left over from the old packed column days on the SP-1000 column. I am not sure if anyones really considers them since the cap column approach became state of the art long ago.

I believe we just stuck with whatever internals we liked using and shugged off the retention time issues (I guess its a bit like the pirates code ).

In 8260b section 7.3.2.2 says that most targets analytes should be within .8 to 1.2 RRT not that they have to be or all could be.
In 8260c that wording was removed.
For the next update on 8000 the wording for RRT will be changed to something closer to current practice.

Thank you for you reply!
Actually,in 11.3.2.2 of 8260C they also mentioned:"IS selection should permit MOST of the component...etc...".
I have neglected the word "most". .
So, thanks for you, guys, I hope, I can relax about RRT.

Thanks, again