Analysis of creams

The possibilities of the gas-liquid chromatographic analysis with flame ionization detection of creams of the o/w emulsion type were investigated. Interferences by cream base components in the determination of the active compounds were studied. It appeared to be possible to determine active compounds with a retention index lower than 1900 onov-17 (e.g. methyl salicylate, menthol, thymol, camphor) without clean-up of the cream samples; for the determination of compounds with retention indices between 1900 and 3700, a simple clean-up step suffices. The possible analysis of some of the cream base components together with the active compounds of the creams was investigated as well. Cetomacrogol emulsifying wax, lanette wax sx and cetiol v could be determined easily, whether or not a sample clean-up step was incorporated.     

Analysis of creams

The possibilities for the determination of active components in creams by acid-base titrations in non-aqueous solvents were investigated. Interference by cream-base components with the titration of weak organic bases and their halides with perchloric acid in acetic acid, and with the titration of weak acids with tetrabutylammonium hydroxide in N,N-dimethylformamide were studied. It appeared to be possible to determine alkaloid halides, salicylic acid, hexachlorophene and methyl salicylate without previous clean-up of the cream samples.     

The analysis of creams; a critical review

Qualitative and quantitative procedures for the analysis of creams of the oil-in-water type are reviewed and discussed, with special attention to the clean-up methods. It is concluded that systematic investigations have hardly been reported, except for creams containing corticosteroids.In honour of Prof. Dr. M.Langejan on the occasion of her retirement.     

25 Jaar LNA

Voordracht gehouden op het symposium 25 Jaar Lna op 1 September 1981 te 's-Gravenhage.     

Analysis of creams

A standard procedure, consisting of twotlc systems, for the qualitative control of creams is presented. All common cream excipients, except those of very high polarity, are separated in a simple gradient elution system, using diethyl ether as the eluent in a chromatographic chamber saturated withn-pentane. The very polar cream base components are separated usingn-butanol-glacial acetic acid-water (20+2+5) as the eluent. The chromatographic behaviour of common cream excipients as well as threefna cream bases and four commercial cream bases is discussed.     

Analysis of creams

The possibilities of applying reversed-phase high performance liquid chromatography to the analysis of o/w emulsion type creams without preceding sample clean-up were investigated. The Chromatographic behaviour of cream base components and active compounds in reversed phase systems consisting of methanol-water mixtures as the mobile phase and a chemically bonded octadecyl stationary phase, was studied. A number of active compounds and the preservative (sorbic acid) could be determined — often in one Chromatographic run — without complications, by simply dissolving the sample in a suitable solvent mixture and injecting an aliquot of the solution into the Chromatograph. Separation was achieved by the proper choice of methanol content, pH and ionic strength of the eluent. The compounds were detected by uv absorption. Some of the lipophilic cream base components could easily be determined in the same manner, with methanol as the eluent and with refraction index detection. The developed procedure was applied to the analysis of a number of creams. Some of the results are presented as examples, demonstrating the suitability of the method for quality control purposes.