Chromatography Forum

Hi all. I currently have an Agilent 1050 with a DAD. I was asked to look into a procedure measuring phenolic content of wine. The older methods (Non-LC) that I found are pretty vague. I found this article to be quite interesting.

"Simultaneous Determination of Nonanthocyanin Phenolic Compounds in Red Wines by HPLC-DAD/ESI-MS"
Monagas, Suarez, et.al.

The column is similar to what we have currently, the one suggested is a Waters Nova-Pak C-18 (300mm X 3.9mm X 4mm) which we would likely order.

My problem is that the extraction procedure suggests using diethyl ether and ethyl acetate. Our hood space is limited, does anyone know of any other possible way to extract phenolics?

Thanks!
Brian

has to be done in the hood anyway

My hood is 28X22X24, so I have some space. I can take the balance out and the little portable bunsen burner. It is in use currently as the photo shows.



KD setups would be too tall I would think...

I think it's a good idea to take the balance out the hood. Does it ever stabilize in there?

Personally, I'd try first without extracting. There would be two reasons to extract: (1) remove analyte compounds from impurities (2) to blow down the extraction solvent to concentrate, as you likely don't want to inject from a water-immiscible solvent. So I'd try without extracting first, and take up in methanol second, before I try manual liquid-liquid extractions.

Yes it does stabilize in there as long as the doors are closed on it. The people previous to me designed the lab on a hard wood floor so that if people walk by the balance it changes due to vibrations.

It also comes with incandescent lighting. I'd prefer fluorescent since it gets awfully hot in here. We also have sky-lights but it is Oregon so you get to see that it is still raining.

The agilent 1050 in the background is currently running since we are doing malic and acetic acids via HPLC at the moment. We also see a bunch of other small organic acids which not all have been identified yet, but we have good ideas what each peak is.

Pictured is also Beca who is prepping samples.

Thanks consumerguy. We might give that a try.

That looks more like a balance cabinet than a fume hood to me, but I've no knowledge of US laboratory facilities. If so ( no external extraction duct or massive carbon filters ), you might as well perform the extraction in the lab, realising the solvents are flammable and volatile, and leave the balance in the cabinet.

If your health and safety regulations don't allow chemicals in the lab, ask management for suitable resources.

However, you also really have to confirm which of the diverse classes of phenolics you have been asked to measure, and then choose a sample prepartion and analytical technique that's suitable.

I would look at some review articles, and also sources like the Journal of Food Science.

You may find the following helpful, as it apparently discusses all the different classes, and the relative merits of the methods for the different types of wines.

“Phenolics: A comparison of diverse analytical methodsâ€