Hello Sasi

A good point to start would be Gel Permeation Chromatography (GPC) with a Refractive Index (RI) detector. UV won't work since sugars don't have UV chromophores. A quick google will give you a couple protocols to try out.

Thanks Christian Krill, i have got couple of protocols to start with. :-)

Yes GPC is the best. I have done several times such analysis. Worked on several iron dextran products.  A simple GPC instruments setup and conditions are provided here. You may try that.  As you know dextran comes wide range of molecular weight distribution, the GPC peak represents a distribution of molecular weight, if the system is calibrated wit dextrans of known mol wt.

Chromatographic System:

The liquid chromatograph is equipped with a refractive index detector maintained at a constant temperature of 45 ºC and two 7.8 mm x 30 cm columns set up in series that contain packing L39 with pore size of 1000A and 120A respectively.  The column temperatures are maintained at       45 ºC ±2 ºC and the flow rate is about 0.5 mL per minute. Chromatograph the system suitability solution and measure the peak areas as directed for procedure; the resolution R, between dextran and glucose is not less than 4.0. Chromatograph the standard solutions, and measure the peak areas as directed for procedure using a suitable program, plot the retention times of the standard solutions and their molecular weights to generate a third order (Cubic)  calibration curve. The correlation coefficient obtained is not less than 0.98.

Procedure for determination of molecular weight:

Separately inject equal volumes (about 25 µL) of each standard solution, System suitability solution and the test solution in to the chromatograph, record the chromatograms and measure the retention times and peak areas. The molecular weight of the complex is calculated from the calibration curve. The molecular weight distribution curve of the sample is sliced into fractions.

Calculate the weight-average molecular weight, Mw, as follows:

                                    MW = ∑ (ATMT)/∑AT

and the number-average molecular weight MN, as follows :

MN = ∑ (AT)/∑ (AT/MT)

Where,

AT = Area of each fraction of the sample distribution

MT = Corresponding mean molecular weight of each fraction as determined from its retention time on the calibration curve.

Thank you Christopher

I read literature on the use of ELSD detector with HPLC  in determination of dextrans, i am gonna try this and will update if this works

Hi Sasi, any update on dextrans analysis using HPLC ELSD? I'm also interested in this particular protocol, can you give me the link to the literature you mentioned? 

We've used HPLC ELSD successfully for PEG analysis.

Many thanks.

Hello, Remigius Wirawan,

sorry, we decided to go for FITC-labelled dextrans in our study hence we did not use any HPLC ELSD method