glycerol

[sepscientologist]

Anybody know how to measure glycerol? I thought ion exlusion but I know glycerol is not stable in acid.

[chromatographer1]

RI detector with 100% water mobile phase on a C18 works wonders.

best wishes,

Rod

[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.

[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

[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.

[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

[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%.

[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

[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.