Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: onurtosun on July 04, 2015, 05:15:35 AM
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Hello there,
After a filtration in manufacturing process i have a mixture of isopropyl alcohol and water, saturated with sodium chloride and sodium glycolate. Estimated IPA content is between 80-90 %. I want to measure the accurate quaintities of IPA and water seperately. I am not sure but as is read, the most useful equipment is gas chromatography for this analysis. Can you suggest a cheaper and attractive method for this analysis? Can i do it also with refractometer or such an equipment?
Already thanks for your answers.
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IPA can be measured by FTIR spectroscopy in the (decimal) absorbance scale in comparison with a blank, at an intense characteristic peak.
CaF2 plates must be used for sampling aqueous solutions. Contrary to KBr, the CaF2 plates are not soluble in water.
Roughly, detection limits are ≈ 3% and accuracy is ≈ 0.5%.
Please, take a look to the IR spectra of IPA and H2O and sodium glycolate, in order to choose the suitable PA characteristic peak that is not covered by H2O and sodium glycolate, respectively.
ATTENTION: The iIR spctra of carboxylate salts (glycolate) are quite different than the ones of the corresponding carboxylic acids (glycolic).
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Alcoholmetric tables exist for IPA/water mixtures, you could distill the ipa and water free of salts, then determine the density as accurately as you can, to get the specific gravity of the mixture, and read percentage off the table. But if you have a GC available, and can quickly use it for your sample, you should get the fastest answer.
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Thanks for your answers.
I dont have a chance to distill the salt solution during the production process, for this reason density method is unsuitable for us.
FTIR method looks like possible but sample preparation should takes a bit longer time. For the last, instead of FTIR can i use near infrared for this analysis?