Chromatography Forum

Hellow

I want to know the mean of 100:1 split ratio.

how it is releated to total flow, split vent flow and column flow

total flow is split vent flow plus column flow.

So 100 ml/min split flow and 1 ml/min carrier flow would be 100:1, and a total flow of 101 ml/min. Now, about that septum purge flow....

Hellow

sorry for mis questioning basically I want to know that if my carrier flow is 15psi,
split ratio is 100:1 , them what does it mean can vey dead volume inject in the column,some thing like this
100+1 =101
100/101=0.99 part of 1 microliter is subjected to column

am I right ? i am not sure so plz tell me right thing

thanks to all

I strongly recommend that you obtain some basic information on your GC by consulting technical information available on WWW- both at instrument manufacters like Agilent, Varian, etc. and educational institutes.

Basically, because the GC column diamater and stationary phase is so small, you can only add a very small sample in gaseous form to the column, and gases expand to several hundred times the injected liquid volume. Let's use 500 times increase in volume.

So, if you inject 1 ul, and have set the split ratio to 100:1 by determining the flow out of the column ( 1 ml/min ), and the split vent ( 100 mls/min ), then you are effectively injecting 5 ul of gaseous sample solution into the column.

The septum purge is a small gas flow ( usually about 2 ml/min ) that washes underneath the septum base in the injector out to waste, mainly to stop any volatile breakdown product from the septum and sample wiped from the needle going into the column - which would cause tailing and extra peaks.

This is all very basic informafion covered on all introductory courses to GC. Use Google..

Bruce Hamilton