I produced PHB polymer from Bacteria, I need an easy method for M wt.determination for polymer.
Hi Kareem
"Easy" depends on the equipment that you have and of the experience of the operators.
For polymers, sometimes only an average mass distribution is possible, and even for that you need specialized MS workstations. MALDI is a a good choice for Proteins, because you have a lot of NH2 groups that you can ionize and charge. For Carbohydrates, the mass is limited at around 10 kDa, because the Ionization is to weak and the molecules don't "fly". There is a chance with SEC/GPC, but to have propper informations you need to use a standard method and a special software is required to calculate the average mass parameters. Maybe you have acess to a FFF (Field Flux Fraction), this is a liquid system for bigger molecules up to nanoparticles and colloids, but also her you need a reliable standard procedure to be able to suggest molecular weights. A simple way is f.E. the permeability at ultrafiltration membranes, where you can check at wich porous size the molecule is retained, this shrinks the search area a little bit. Unfortunately, this UF-membranes have calibrated sizes to proteins, so if you have different molecules, you have to find a way to adapt the results.
There are protocols for ultracentrifugation that cover the same subjects and help you shrink the search area a little bit.
Mr. Frank is right..you can use some of the mass spectroscopic techniques (MALDI, LCMS etc.) for the determination of your compound..
If you do not have access to MALDI or GPC, the simplist (technologically)/easiest is dilute solution viscometry which requires a water bath, a Ubelode or similar type capillary tube, a stopwatch, and the Mark-Houwink equation.
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