By primoza on Monday, June 2, 2003 - 05:13 am:
Varian offers four time better S/N ratio and how is by that in practice (e.g. analysis of herbicides at ng/L level).
By Ralph on Tuesday, June 3, 2003 - 03:14 am:
I assume that it is through improved chemical stability of the stationary phase which leads to 4x less bleed, which in turn gives lower noise. In practice a detection limit of 12ng/L should be lowered to 3ng/L. Lower bleed will also give a longer column life and less detector fouling.
However, the claim is for "UP TO 4x better" so it depends on what column it is being compared to and assumes that all other parts of the instrument are working at optimum.
Regards,
Ralph
By Ralph Calvert on Friday, June 6, 2003 - 02:41 am:
In fact I have just read the leaflet on it and the claim is for 2.5 better signal to noise
Ralph
By jaap de zeeuw on Thursday, June 12, 2003 - 05:18 am:
The performance of a GC depends on many parameters, not only the column. Important is to reduce the total background of the GC to a minimum. The contribution of the column is something we can control, the other parameters are in hands of the operator. The FactorFour program is based on a lower bleed specification which is obtained by an optimization process in fused silica surface chemistry , stationary phase stabilization and conditioning. As reference the published specs of a good column and leading brand (DB-5ms) were taken. The spec of the FactorFour VF-5ms columns could be set a factor 4 tighter meaning that the average bleed will also be significantly lower. Practically a lower bleed will give advantages of which one is an improved signal to noise. We have measured for PAH a factor 2.5 better signal/noise using MS. If anybody wants to know more details,drop me an E-mail ( jaap.de.zeeuw@varianinc.com )
Jaap