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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: mobfesk2 on September 08, 2007, 01:49:10 PM

Title: Detection of lactose in a product??
Post by: mobfesk2 on September 08, 2007, 01:49:10 PM

Hi Chem Forumers,

If I have a product of sialyllactose, how would I know how much lactose I have in there? Is there any detection method?

I have a proton NMR spectra of sialyllactose but don't know if this helps in detecting the amount of lactose

Thanks for any suggestions!

Title: Re: Detection of lactose in a product??
Post by: Dan on September 08, 2007, 05:41:10 PM

If you can identify and differentiate peaks in the 1H NMR corresponding to the sialyllactose and lactose protons, you could use the peak integrals to get an approximate ratio of your products.
I don't know how easy this is going to be, since we are talking about a complex spectrum you may have some issues with overlapping peaks etc.

Maybe try looking at the ratio of the protons at the anomeric positions, as these should be fairly well outside the most crowded region. You may have issues with the water peak overlapping with these though (I´m guessing you're in D₂O). Without seeing the spectrum, I can't be sure this is a feasable method. In any case, it is not very accurate.

Could the components be separated on reverse phase silica perhaps?

Title: Re: Detection of lactose in a product??
Post by: mobfesk2 on September 08, 2007, 06:18:16 PM

Hey Dan!

Thanks for your reply. Could I send you the fid file of my spectrum?

I think I have something like 80% purity because there's peaks of acetic acid i.e. I eluted my product on a G-15 sephadex column using acetic acid as the eluent. But this can be removed by freeze drying so maybe the purity is higher?

I've also done a proton NMR of lactose in D2O to see if there are any peaks which correspond to my sialyllactose product. I haven't got round to analysing the data properly.

Could I send you both the sialyllactose and lactose NMR spectra's?

Thank you so much for your reply! I really appreciate it!