Chromatography Forum

Dear members of this forum,

I need your help in order to solve an analytical problem. I am working with glucosamine sulphate assay and I have problems.
According to USP the mobile phase is buffer phosphate (1 ml of phosphoric acid in 2000 ml of water adding potassium hidroxide to reach pH 3) and acetonitrile, the proportion is 3:2; the wavelength is 195.
I have problems because the signal is very small, the drug is very soluble in water and there are any strange peaks; the peak purity is not good.
I try to disolve the drug with mobile phase, I worked with differents distilled water and change the proportions of acetonitrile in the mobile phase without any luck.
The pharmacopeia works with C8 but I think any phase stationary with more polarity as ciano or phenyl is better owing to the drug is soluble in water.
I would appreciate any help in order to help me,

Diego

Hi Diego

I previously worked with the same method but did not get it to work properly. I don't know how USP could publish an analysis method for sugars that is run on a C8 column without any previous derivatization steps. After being in contact with USP they agreed that it was not a "suitable" method...

However, in USP there is monographs for glucosamine tablets as well as for glucosamine/chondroitin tablets (at least for two years ago when I worked with this analysis). We chosed to work with the method for glucosamine/chondroitin tablets since it involves a derivatization step which facilitates both the separation and detection.

I would think that you could use any kind of derivatization technique intended for sugar analysis...

/Peps

The UV response of glucosamine at 195 nm is very poor. And used column (understand C8 stationary phase) is not suitable for separation of glucosamine too. I would try the amine phase and some derivatization step (preferably post-column derivatization with OPA and fluorescence detection) - see Peps guote !