How much a substance converted into a crystals?

5 posts / 0 new
Last post
mikevnjp
mikevnjp's picture
How much a substance converted into a crystals?

How much a substance converted into a crystals?

Dear all,

I am quite new in biophysic.

I have successfully crystallized one inorganic substance. I would like to know which percentage of this substance was crystallized.
X-ray diffraction cannot help in my case, could you please give me some hint?

Thanks for any help!

soniabedi
soniabedi's picture
Hello,

Hello,

To my knowledge, XRD is the best technique for determination of degree of crystallization of a substance.
But, if its not working, a try can be given to DSC. Calculation of degree of crystallization by the data obtained from this technique is also quite easy simply by making use of exothermic and endothermic peaks.

You can also refer to the following article:

http://www.risoe.dk/afm/symp22/pdf/risoms22_377-382.pdf

Regards

cliff99
cliff99's picture
Sorry for the tardiness of my

Sorry for the tardiness of my reply, but I am new to the Forum.

For inorganic crystals there is very little, if any, solvent incorporated into the crystal lattice. So a simple calculation based on the dry weight of your crystals compared to the starting amount of material should give you a reasonable estimate of the actual per cent of material in the crystals.

For biologic matierals, such as protein or nucleic acids, a significant amount of solvent is in the lattice - upwards of 50% and either the crystal density needws to be determined experimentally, or the approximate unit cell dimensions are needed from X-ray analysis to estimate how much of the crystals are the molecule of interest via the Matthews' Equation (B.W. Matthews "Determination of molecular weight from protein crystals", J. mol. Biol 82:513 (1974)

Dominiquest
Dominiquest's picture
As cliff said, you can use

As cliff said, you can use the difference in mass of the original sample and crystallized sample. I too am working on crystallization at the moment and use this technique... The only point to consider here is that your initial sample is completely pure. Once you go for crystallization, dry the crystals (not by using an absorbant but by lyophilization) before you can take the final weight. This should give you an accurate value.

Tirumal Rao
Tirumal Rao's picture
hi,

hi,
The amount of entropy a substance has is the amount of structure which needs to be broken down to convert substance from perfect structure (zero K crystal) into ... There is obviously much more chaos (less structure) in mixed gases than ...
u jsu specify the cristals . diffrent cristals are diffrent level
its having more kind of cristals thst depend on mass level
estimation is differ inorganic and organic cristals and depends on molecular weigt and size to convert substance.
Thanks
Tirumal