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glycerol
Posted: Fri Dec 07, 2012 5:06 pm
by sepscientologist
Anybody know how to measure glycerol? I thought ion exlusion but I know glycerol is not stable in acid.
Re: glycerol
Posted: Fri Dec 07, 2012 6:37 pm
by chromatographer1
RI detector with 100% water mobile phase on a C18 works wonders.
best wishes,
Rod
Re: glycerol
Posted: Fri Dec 07, 2012 9:31 pm
by Consumer Products Guy
We've used capillary GC with BSTFA derivatization to do this for decades, see "Quantitative Determination of Glycerin in Soap by Capillary Gas Chromatography", JAOCS, Vol. 64, No. 9 (September 1987)
We use this also for liquid products, and for similar materials such as propylene glycol, glycol ethers, sorbitol, etc. Very straightforward and easy.
Re: glycerol
Posted: Fri Dec 07, 2012 9:45 pm
by chromatographer1
CPG
He is doing biodiesel waste which should contain a bunch of water.
He may wish to make tri-acetates by GC or simply run a HPLC method which if he has one makes a lot of sense in a production mode.
It depends upon the actual content of his matrix which can vary.
Rod
Re: glycerol
Posted: Sat Dec 08, 2012 12:53 am
by Consumer Products Guy
CPG
He is doing biodiesel waste which should contain a bunch of water.
Rod
Consumer products can be 90% water. That's OK with us.
Re: glycerol
Posted: Sat Dec 08, 2012 1:00 am
by chromatographer1
90% ! That is impressive.
Can you use 5mg or more of sample per mL , and look for levels below 1000ppm with the BSTFA type reagents?
I assume he probably won't be looking at very low levels ( xx ppm) in the biodiesel waste.
best wishes,
Rod
Re: glycerol
Posted: Sat Dec 08, 2012 5:58 pm
by Consumer Products Guy
About 30 years ago we took on a project for a customer to assay for trace levels of glycerin in bar soaps, for legal claims. These were bars made by continuous process instead of the kettle process, so only trace levels remained. We could readily quantitate levels like 0.01% in the product.
High glycerin levels in transparent bar soaps could be about 10%.
Re: glycerol
Posted: Sat Dec 08, 2012 7:44 pm
by Karen01
What type of chromatography/detection makes the most sense for you depends on the matrix it is in and on what else you want to measure along with
I use HILIC on the Water's amide... For HPLC with RI detection, for UPLC with ELSD. That makes the most sense for what we do. Samples are aqueous. We are looking for 1 g/L and up
- Karen
Re: glycerol
Posted: Tue Dec 11, 2012 8:04 pm
by Vlad Orlovsky
here is highly sensitive UV-VIS method for analysis of glycerol:
http://www.sielc.com/Compound-Glycerol.html
Contact me if you have questions.