Guay F, Bisaillon S. Determination of the average molecular weight of nonionic emulsifiers by vapor-phase osmometry.
J Pharm Sci 1984;
73:392-4. [PMID:
6538906 DOI:
10.1002/jps.2600730326]
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Abstract
Standard nonionic emulsifiers are heterogeneous by nature. Their reported molecular weight is unreliable, especially when several lots of the product are used in a study. The number-average molecular weights of two nonionic emulsifiers, poloxamer 188 and polyoxyethylene (23) lauryl ether were determined by vapor-phase osmometry. This determination is essential when the concentration should be given in molarity rather than in weight per volume. A discrepancy was noted between the number-average molecular weights of two lots of poloxamer 188. That difference is taken into account prior to the establishment of any comparison of the behavior of the emulsifiers.
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