How does find out Methanol concentration in a solution which is containing citric acid, methanol and water? Any chemical or physical testing method to calculate each concentration?
the easy way is use gas chromatography to detect volatile methanol. You can direct inject 1 uL of in the injector port. Go to chromatography catalog like Supelco or Restek to find the condition to separate volatile solvent. The hard way is determine water with Karl Fisher, determine citric acid acid separately using chromatographic method and substract from the total.
Also I found this off the internet http://www.sciencedirect.com/science/article/pii/S0021967397010558
remember, you can find anything on the net.
I am not much expert for the same , but if your sample volume permitts and you have large sample volume, you can go for distillation, where you can seperate out Methanol, and then karl fisher titration for water content of same sample and now you had two and can have the rest value by subtration of two from the original
The easiest way could be NMR. Put a well measured amount of the mixture (aprox. 5 uL) in a NMR tube. Add about 2 uL of an internal standard (i.e. pure acetic acid) and measure a proton NMR in D2O. You can have citric and methanol moles by comparison with the internal standard, and water is the rest (you cannot measure water because D2O is usually wet).
Thanks everyone. I need a quick testing method to do continuously in a process line? Anyone know any method except Gas chromatography, Hantzsch reaction, Colorimetric analysis, Karl fischer titration and HPLC?
One can use Raman or NIR spectroscopy to measure this. Both are tool sthat can be used for real-time process monitoring. It will require the development of a calibration from sample set with the known concentration of all the samples in the matrix. What are the concentration ranges of the analytes of interest?
I found the "alcohol meter" from this site
http://www.selectscience.net/products/snap-50-portable-alcohol-meter/?prodID=197102
You may oxidize methanol to formic acid, then determine its concentration by spectrophotometeric methods.
for further information you can see 'Spot tests' books.
Amperometry. You'll have to build a standard set and may need to use PLA due to the citric acid.
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