Glycoalkaloids

[MTM]

I'm trying to apply a method for quantification of glycoalkaloids (Tomatine and tomatidine).

I'm using a HPLC/PAD unit (Gilson) and a ACE 3 C18-AR.

Detection: 202 and 205 nm

Which reference value I should use for this wavelenght?

Thanks for your atention.

[carls]

What is your mobile phase composition? Is it retained with RPLC? Have you considered HILIC?

[MTM]

I'm using Methanol and CH3COOH

Thanks for your atention.

[carls]

Please provide your chromatographic conditions. Is your method isocratic or gradient? What are the column dimensions, temperature and flow rate?

What are the retention times of your 2 analytes? Please post a chromtogram if possible.

Instructions for embedding chromatograms in a post are shown here:

viewtopic.php?t=2617

"Which reference value I should use for this wavelength?"

Do you mean what detector reference wavelength should be used? If so, why do you think you need one? A reference wavelength is not always needed or helpful. Try it first without a reference. If the baseline drift is too high, 360nm +/- 50nm commonly used

[lmh]

You don't need hilic for tomatine and tomatidine. They are well-retained on C18. I don't envy you trying to detect them by UV, though. I use LC-MS for the job.

[Bryan Evans]

Below is an LC-MS application for a-solanine & a-chaconine from potato. This separation was done using Cadenza CD-C18:
http://www.imtaktusa.com/site_media/fil ... TI189E.pdf

As already stated, it will be difficult to do this analysis with UV detection.