Dear Stuart

If we take pure methanol and we know its water content is 0% and add 
castor to the correct concentration , mix well,  we now have a fuel mix 
that we know does not have water in it and is the correct 
castor/methanol ratio.

Measure the Rf value and now we have the Rf value of good fuel.

Any water in the fuel and the Rf of a similar but water contaminated 
mix will be different.  Also if the organisers get the oil/methanol 
ratio wrong the Rf value will not match the standard fuel either.

Rf values are excellent for binary mixtures, one substances dissolved 
in another.  For binary mixtures with extra contaminants then the 
curves may go up or down but our set point is always a standard mix.  
If the Rf value changes we can say, there is something wrong with this 
fuel, but we can not with any certainty tell what it is.  Methanol with 
toluene or benzine as a contaminant will change the Rf value, and if 
someone adds nitro to the fuel the Rf will change too.

With the exception of water most contaminants will make the fuel smell 
different.  We have our own built in Gas-Liquid Olfactory Detector 
(GLOD, oh my god I have invented a new acronym - Glod detection !!!) 
and we are likely to "smell a rat".  Methanol is sometimes contaminated 
with traces of petrochemicals (the industry is seriously bad at 
recycling properly cleaned 44 Gal drums).

Oh hell, I can see a project coming on, a set of castor V methanol 
tables along with a set of standard fuel V water tables.

Would they help ?

Failing that we could look for a portable Gas Liquid Chromatograph 
system, Instant on site analysis of all the components in a fuel mix.  
Nahhh, it would cost too much, then again .... it could be very 
interesting.

Lance