particle size analysis by malvern

[morningstar]

hi,
i've a problem analysing the particle size of a drug i'm dealing with,
the drug is soluble in all solvents like water, methanol, ethyl acetate, liquid paraffin, sunflower oil, ccl4, chcl3, but found to be insoluble in acetonitrile


i've checked for a dispersion in acetonitrile using various surfactants, but the disperssion is not very good

i need to try some combinations of solvents


i need help regarding this matter

regards
morning star

[tom jupille]

If you are dealing with a dry powder, what about simple air classification?

[morningstar]

ya that could be done but the problem is my sample is highly hygroscopic


is there any alternative ??? i mean a dry method where in we can use some kind of chemical which absorbs moisture from my sample

let me explain

i take a chemical which can absorb moisture from my sample, first i take its PSD, then i add a known quantity or some quantity of that chemical to my sample and go for the scan again....and get the difference?????? i don't know .... i've tried all possible solvents and combination of solvents to develop a wet method, now i'm left out with only dry method



i need help regarding this



regards
morningstar

[Bruce Girton]

It is curious to me that the drug is soluble in both liquid paraffin and water. Did you try heptane or toluene? Other suggestions: a saturated, submicron-filtered solution of the drug; a perfluorinated solvent like perfluorohexane; a dry suspension using nitrogen or anhydrous air.

[tom jupille]

i take a chemical which can absorb moisture from my sample, first i take its PSD, then i add a known quantity or some quantity of that chemical to my sample and go for the scan again....and get the difference?????? i don't know .... i've tried all possible solvents and combination of solvents to develop a wet method, now i'm left out with only dry method

You should be able to find a bead-type dessicant vastly different in size from your powdered drug. Using dried air or N2 as suggested in the previous post should also help.

[morningstar]

hmmm quite strange that the drug is soluble in
a variety of solvents ranging from highly polar to highly nonpolar .... but insoluble in acetonitrile... i tried to sonicate the sample in acetonitrile ...but it formed a gelatinous ppt.


i need a solvent which is viscous enough to hold my sample and the sample should be slightly soluble ...so that i can prepare a saturated solution of the drug in it and use it as my disperssant.....no use tried in every possible solvent ....freely soluble in all the solvents



so opted for conventional sieve analysis ...but as my sample is highly hygroscopic... have to carry out in nitrogen atmosphere:-)




anyway thanks for sharing the info .... please let me know incase there is a possibility of developing a method using malvern


regards
morningstar