ERRORS IN THE ANALYSING OF PERFUMERY RAW MATERIALS 43 On the other hand, if an internal standard is injected, most of these difficulties can be avoided. If it is understood that such differences can occur with exactly the same equipment and probably the same operators, how much more difficult does it become to repeat results with different equipment and different operators. We have repeatedly found that even by putting the two samples consecutively into the same equipment, one simply does not obtain an exact reproduction of results. Dr. Kovats has so far restricted himself to hydrocarbons which are only to some extent related to the materiMs encountered in our industry, but nevertheless his methods and techniques have possibilities. Everybody agrees that publication of data is highly desirable. It seems that so far they have very largely been kept confidential, whatever the reasons may be. When I was a member of the French group of the Inter- national Standards Organisation I discussed the matter with leading mem- bers of the French industry, and with others concerned. Although they all agreed, to date the matter remains wishful thinking. MR. J. H. lV[ERz: Would you agree that the difficulties with isomeri- sation and catalytic decomposition of terpenic compounds are largely brought upon themselves by gas chromatographers still using the operating conditions, such as high temperature, high stationary phase concentration and columns, which were necessary in the early days of relatively insensitive detectors ? Is the lower operating temperature which is possible with capillary columns nullified by the need to vaporise the sample completely by means of a flash-heater in order to achieve representative stream splitting ? T• LECTURER: With capillary columns, it would certainly be advisable and advantageous to inject directly into the column. MR. J. H. M•Rz: How can you inject such a small sample ? T• L•½TUR•R: That is why I am against capillary columns. For our industry, there are pros and cons in capillary columns, and generally, in my opinion, the disadvantages are greater than the advantages. In matters of research, where only minute quantities might be available, the capillary column can have enormous advantages, but my comments largely refer to the technical use of the capillary column in everyday laboratory work. It is quite true that during the development stages of GLC, the amount of liquid stationary phase has been very largely exaggerated and where initially it was used in the proportion of 30%, now it is used more often than not in the proportion of about 20% but even so, many authors, including Dr. Klouwen, would say that 5, 3, 2 and even 10/0 would be enough.

44 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS One of the inter-related factors is, of course, the quality of the solid support. It is a fact that today one can get some types of Celite which are very easily, or relatively easily, impregnated by a very much smaller propor- tion of liquid phase than was previously the case. When using two-column equipment, one of the columns is used as a reference and the other for an injection of the sample. In this way, dis- turbances which could be introduced by alteration of the liquid phase are corrected. Has anyone any experience on this point ? DR. }V[. It. KLOUWEN: We have no experience, but the new apparatus of the F. & M. Corporation possesses such a double system. •MR. J. •m. BLAKEWAY: On the subject of publication of relative retention times, I believe the people who get most of this information are the essential oils manufacturers themselves, and they will spend a great deal of money identifying at least some of the minor components of essential oils. I myself cannot see them publishing this data. Does anyone think it likely that they will publish information about the minor components of some of these rarer essential oils, which wou!d be of great interest to everybody ? I feel that the academic bodies will have to publish the information in the first place, after which industry can make more general use of it. Perhaps the French School of Pharmacy, in Paris, can be persuaded to publish something initially. }V[R. Gr. J. E. HACKFORTH-JONES: In practice we are often confronted with a choice between two oils, one of which we suspect to have been interfered with to some slight extent. For example, one might suspect the addition of 10% of the cheaper Geranium Egyptian to Geranium Bourbon, an amount, the detection of which by smell alone, would be difficult. Can you advise which type of equipment would be most suitable for the resolution of this problem ? THE LECTURER: With Oil of Geranium, which is very much more complex than many others, I, and my collaborators, have carried out a considerable amount of research, as probably has every major user of geranium oil. have found 90 different bodies of which 60 are of interest odourwise but it is very likely that altogether there are more than 150 constituents present in this or similar oils. In such a case, the capillary column has an advantage, and even though one would not be able to identify all the individual com- ponents with it, graphically it probably shows the number of ingredients better than most other columns. With an ordinary column under normal working conditions, i.e. with an available time of half an hour, one would not expect to get a graph containing more than about twenty-five peaks.