Conductivity as a method for determining the solute concentration on apolar solvent: is it possible?

[guerky]

I'm trying to find a relatively simple method for determining the concentration (up to at least 1% of accuracy) of an organic compound in methylciclohexane from a liquid-liquid extraction in order to provide standard crystallization conditions downstream (many recicle streams from one batch to another turns this crystallization in a living hell; eliminate then is out of cogitation).
I already have conductivity meters that act separating the organic phase from the aqueous. The range of conductivity is very broad (13 to +1000 mSiemens), and the organic phase have a conductivity around 19 mS on average, oscillating between 13 and 26 mS. An oscillation of 3 or even 6 mS can be observed even on operation stops, so i know for sure that the conductivity meters calibrated for this rangeare could not be used to build a curve correlating the concentration to the accuracy desired.

The question is: it is a fact that even apolar media presents some conductivity, and this conductivity is a function of the species and their concentration in the media (the temperature is kept constant), so a conductivity analysis calibrated for a smaller range (like 0-30 mS) would have the sensibility for detecting solute small concentration variations? I could request a lab study for creating a curve fiting this data if it correlates to concentration in a significative and measurable way.

If not, what other methods do you suggest for measuring organic solutes concentrations on organic solvents in industrial equipment?

Thanks.

 

[georgeverghese]

If this organic solute is an optical isomer, then a polarimeter may help?

Are there any other solutes / contaminants in this MCH?

 

[guerky]

The molecule have optical isomery. How a polarimeter could work, in this case? (if you have some material about functioning, uses and/or installation of these instrument i would apreciate).
About other solutes, only in small amounts. The dried up product minimum concentration is 97%, but yes, MCH has some minor contaminants.

 

[georgeverghese]

Looks like you are in luck - you can find the theory on this in many chemistry textbooks - also talk to a process analyser vendor and tell them that these are optically pure isomers you are working on - polarimetric analysers are not uncommon.

 

[mfelzien]

See a book by Bard-Faulkner on electrochemical methods and look around for cyclicvoltometry and chronocoulometry. These techniques are used to determine what you are talking about.

 

[guerky]

Thank you.
I will search for those references.