THE INTERFERENCE OF NONIONIC EMULSIFIERS WITH PRESERVATIVES VIII

Johanna Poprzan; Maison G. Denavarre

INTERFERENCE OF EMULSIFIERS WITH PRESERVATIVES VIII 87 Another observation indicates that the incorporation of 20 per cent of a quaternary germicide, such as Hyamine 10 X, Roccal or Ethyl CETAB based on the weight of the nonionic, will prevent growth in the presence of 0.2 per cent methyl p-hydroxybenzoate but not in its absence. These tests have now been running continuously for eighteen months. S UM/VfA RY The prevention of inactivation of preservatives by alkoxylated nonionics appears a step closer to solution. The addition of 10 per cent and in some cases less, of ethyl alcohol propylene glycol 1,3-propanediol 1,4- butanediol or 2, methyl 2,4-pentanediol is effective for this purpose against four bacteria and •. ni•er, using 0.2 per cent methyl p-hydroxybenzoate and 2 per cent Tween 80 or G-3720. These results are to be expanded to include other preservatives, nonionics and micro6rganisms. REFERENCES (1) Barr, M., and Tice, L. F., •. •im. P/•arm. •issoc., $ci. Ed., 46, 445 (1957). (2) aleNavarre, M. G., y. $oc. Cosmetic C/•emists, 8, 68 (1957). (3) Pisano, F. E., and Kostenbauder, H. B., Am. Pharm. Assoc., Sci. Sect., Los Angeles Meeting, April (1958). (4) Lach, J. L., Ravel, K., and Blaug, S. M., •. •im. Pharm. •issoc., $ci. Ed., 46, 615 (1957). (5) A brand ooe N-trichloromethylmercapto-4-cyclohexene-l,2-dicarboximide. R.T. Van- derhilt Co., Inc., New York 17, N.Y. (6) A brand of lauryl isoquinolinium bromide, Onyx Oil and Chemical Co., Jersey City, N.J. (7) A brand ooemercaptobenzothiazole, R. T. Vanderbilt Co., Inc., New York 17, N.Y. (8) Tetramethyl thiuram disulfide. (9) A brand of polymethylene carboxvlate, B. F. Goodrich Chemical Co., Cleveland 15, Ohio. (10) A brand of ethoxylated cellulose, Carbide and Carbon Chemicals Div., Union Carbide and Carbon Corp., New York 17, N.Y. (11) A brand of methyl cellulose, The Dow Chemical Co., Midland, Mich.

ACID NUMBER AND SPREADING INDEX OF THE HUMAN SKIN SURFACE LIPIDS By I2RA•Z HERRMA•N, M.D., W. M. Coo•, M.D., L. HARBER, M.D., R. SCHEa, M.D., and L. MANDOL* Presented October 8, 1958, Seminar, New York City IN PREVIOUS extensive investigations we studied the amount ("casual level") of the skin surface lipids under various conditions with special attention to their distribution in different areas of the human body surface (1, 2, 3, 4, 5). More recently we investigated the free fatty acid contents of the respective samples, as well as the spreading index (6, 7). The latter term was introduced for the cm. 2 area of skin surface covered by 1 mcgm. of the lipid under investigation--when a given quantity of it is, under standardized conditions, placed on an aqueous surface (6). Assays of the lipid spread on water had been advocated by Jones and collaborators for determination of the lipid quantity (8, 9, 10), since they presumed that the free fatty acids control the spreading ability of the samples and that their proportion in the skin surface lipids is constant. Our investigations had revealed (1) that the spreading index differs from one individual to another for samples collected from a given site so that it is not generally feasible to utilize the index for determination of the lipid quantity: (2) that there are distinct regional differences for the lipids collected from different test areas and (3) that for certain test areas the index tended to increase during the warmer season. Our assays of the acid number which had been carried out on only a minor scale have been greatly expanded. It is the object of this presenta- tion to report on the results obtained to date in addition to those previously published. EXPERIMENTAL Method. The methods of assaying lipid quantity and spreading index were the same as described in our previous reports (1, 2, 6, 7). In order to obtain sufficient lipid quantities per sample for each of the * Dept. of Dermatology and Syphilology, New York University Post Graduate Medical School (Dr. Marion B. Sulzberger, Chairman) and the Skin and Cancer Unit of University Hospital, New York 3, N.Y. 88

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INTERFERENCE OF EMULSIFIERS WITH PRESERVATIVES VIII 87 Another observation indicates that the incorporation of 20 per cent of a quaternary germicide, such as Hyamine 10 X, Roccal or Ethyl CETAB based on the weight of the nonionic, will prevent growth in the presence of 0.2 per cent methyl p-hydroxybenzoate but not in its absence. These tests have now been running continuously for eighteen months. S UM/VfA RY The prevention of inactivation of preservatives by alkoxylated nonionics appears a step closer to solution. The addition of 10 per cent and in some cases less, of ethyl alcohol propylene glycol 1,3-propanediol 1,4- butanediol or 2, methyl 2,4-pentanediol is effective for this purpose against four bacteria and •. ni•er, using 0.2 per cent methyl p-hydroxybenzoate and 2 per cent Tween 80 or G-3720. These results are to be expanded to include other preservatives, nonionics and micro6rganisms. REFERENCES (1) Barr, M., and Tice, L. F., •. •im. P/•arm. •issoc., $ci. Ed., 46, 445 (1957). (2) aleNavarre, M. G., y. $oc. Cosmetic C/•emists, 8, 68 (1957). (3) Pisano, F. E., and Kostenbauder, H. B., Am. Pharm. Assoc., Sci. Sect., Los Angeles Meeting, April (1958). (4) Lach, J. L., Ravel, K., and Blaug, S. M., •. •im. Pharm. •issoc., $ci. Ed., 46, 615 (1957). (5) A brand ooe N-trichloromethylmercapto-4-cyclohexene-l,2-dicarboximide. R.T. Van- derhilt Co., Inc., New York 17, N.Y. (6) A brand of lauryl isoquinolinium bromide, Onyx Oil and Chemical Co., Jersey City, N.J. (7) A brand ooemercaptobenzothiazole, R. T. Vanderbilt Co., Inc., New York 17, N.Y. (8) Tetramethyl thiuram disulfide. (9) A brand of polymethylene carboxvlate, B. F. Goodrich Chemical Co., Cleveland 15, Ohio. (10) A brand of ethoxylated cellulose, Carbide and Carbon Chemicals Div., Union Carbide and Carbon Corp., New York 17, N.Y. (11) A brand of methyl cellulose, The Dow Chemical Co., Midland, Mich.

ACID NUMBER AND SPREADING INDEX OF THE HUMAN SKIN SURFACE LIPIDS By I2RA•Z HERRMA•N, M.D., W. M. Coo•, M.D., L. HARBER, M.D., R. SCHEa, M.D., and L. MANDOL* Presented October 8, 1958, Seminar, New York City IN PREVIOUS extensive investigations we studied the amount ("casual level") of the skin surface lipids under various conditions with special attention to their distribution in different areas of the human body surface (1, 2, 3, 4, 5). More recently we investigated the free fatty acid contents of the respective samples, as well as the spreading index (6, 7). The latter term was introduced for the cm. 2 area of skin surface covered by 1 mcgm. of the lipid under investigation--when a given quantity of it is, under standardized conditions, placed on an aqueous surface (6). Assays of the lipid spread on water had been advocated by Jones and collaborators for determination of the lipid quantity (8, 9, 10), since they presumed that the free fatty acids control the spreading ability of the samples and that their proportion in the skin surface lipids is constant. Our investigations had revealed (1) that the spreading index differs from one individual to another for samples collected from a given site so that it is not generally feasible to utilize the index for determination of the lipid quantity: (2) that there are distinct regional differences for the lipids collected from different test areas and (3) that for certain test areas the index tended to increase during the warmer season. Our assays of the acid number which had been carried out on only a minor scale have been greatly expanded. It is the object of this presenta- tion to report on the results obtained to date in addition to those previously published. EXPERIMENTAL Method. The methods of assaying lipid quantity and spreading index were the same as described in our previous reports (1, 2, 6, 7). In order to obtain sufficient lipid quantities per sample for each of the * Dept. of Dermatology and Syphilology, New York University Post Graduate Medical School (Dr. Marion B. Sulzberger, Chairman) and the Skin and Cancer Unit of University Hospital, New York 3, N.Y. 88

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INTERFERENCE OF EMULSIFIERS WITH PRESERVATIVES VIII 85 SORBIC Acre TESTS It has been thought that the discrepancy between our results and those reported by others using sorbic acid, could be in the medium employed. Both magnesium and ferrous iron have been suggested as forming sorbates less soluble than the free acid. However, magnesium sorbate is far more water soluble than sorbic acid itself. In experiments made with Jaag medium with and without these two ions, no difference in growth was observed. When deionized water served as the medium, the addition of these ions in the concentration found in Jaag medium showed no effect on preservative action. Though Lach (4) has found sorbic acid to be less complexed by poly- glycols than the p-hydroxybenzoates, our work to date, using mainly niger as the test organism does not confirm this. Furthermore, one of us (M. G. deN.) has found that at a pH above 5.0, sorbic acid is a poor pre- servative even in the absence of nonionics in Jaag medium. against niger. 0.1% cationic only* 0.1% cationic plus 2% G-3720' 0.1% MPt 0.15% MP 0.2% MP Ethyl Hyamine Roccal Cetab 10X ++++ ++++ ++++ + ++ _ _ ++++ Figure 4.--Twelve Month Growth of •/. niger in 2% Mixture of Cationic (20%) in G-3720 with Methyl p-Hydroxybenzoate * No other preservative. t Methyl p-hydroxybenzoate. 12 Months Tween 80 q- q- q- G-3720 q- q- G-3810 G-1425 q- q- Figure 5.--Growth •/. niger, in Jaag Medium, 2% Nonionic 0.2% MP* * Methyl p-hydroxybenzoate. MISCELLANEOUS OBSERVATIONS Of the many preservatives tested, we found benzoic, sorbic and dehydro- acetic acids very sensitive to pH in their antimicrobial activity. Ethyl vanillate and the parabens had a fairly wide pH spectrum. In general, we found that the greater the number of moles of ethylene oxide in the ether or ester chain, the greater the inactivation of pre- servative. These data are based on tests of a series of ethoxylated nonyl phenols, glyceryl monostearate, stearic acid and cetyl alcohol. We found •lspergi//us growing slightly in 0.2 per cent formaldehyde (100 per cent basis) in Jaag medium containing 2 per cent G-3720. Similar

86 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS tests with lower concentrations of formaldehyde showed, as would be expected, heavier growth, but in no case was it more than moderate. At the end of one series of tests using Jaag medium, Atspergillus and methyl p-hydroxybenzoate in concentrations of 0.1, 0.15, and 0.2 per cent, we added 0.1 per cent of a commercial perfume compound dissolved by 2 per cent G-3720 to the group. In two months tubes preserved with 0.1 per cent methyl p-hydroxybenzoate showed a very heavy growth. At a concentration of 0.15 per cent methyl p-hydroxybenzoate, a heavy growth took place in one year. At a concentration of 0.2 per cent methyl p- hydroxybenzoate no growth was discernible at the end of one year. It was of interest to note the profound effect of the nonionic G-3720 on the growth of At. niger in Jaag medium containing Duponol C. At 0.1 per cent concentration of Duponol C alone, tubes were free of growth at the end of one year. When 0.1 per cent G-3720 was added, moderate growth was observed in five months. At a concentration of 0.3 per cent G-3720, and 0.1 per cent Duponol C, heavy growth occurred in four days. When the sodium alkyl sulfate was ethoxylated with 11/2 to 2 moles ethylene oxide, moderate growth was readily noticeable in three weeks. Based on a suggestion made in Geneva in 1957, we used five materials because their main action was fungicidal. Jaag medium was made with 2 per cent G-3720 and variable amounts of the fungicides with the fol- lowing results. Vancide 89 (5) showed a very heavy growth in a 0.01 per cent concentra- tion in thirty days. Isothan Q-15 (6) in 0.1 per cent concentration showed a heavy growth in twenty days. Salicylanilide 0.1 per cent took one hundred fifty days to give a very heavy growth. Rotax (7) 0.1 per cent gave a moderate growth in one hundred twenty days, while TMTD (8) 0.1 per cent has shown no growth for nine months. We find that not only nonionics but other macromolecules inactivate preservatives when tested in Jaag medium. Thus, 0.5 per cent Carbopol 934 (9) containing 0.2 per cent methyl p-hydroxybenzoate shows moderate growth of At. niger in from two to four months depending on the alkali used in neutralizing the material. Cellosize (10) can be preserved with as little as 0.15 per cent methyl p-hydroxybenzoate against At. niger. How- ever, 2 per cent tragacanth in Jaag medium shows slight growth of At. niger in five months in the presence of 0.2 per cent methyl p-hydroxybenzo- ate. Methocel 1500 (11) gives moderate to heavy growth of At. niger in concentrations of 0.1 to 0.2 methyl p-hydroxybenzoate. PVP, two types, shows moderate growth of At. niger in 0.2 per cent methyl p-hydroxy- benzoate after five months. We now have indications that the presence of around 8 per cent ethyl alcohol in the preserved nonionic medium, may retard inactivation of the preservative toward At. niger.

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HUMAN SKIN SURFACE LIPIDS 89 three pertinent assays--weight, acid number (A.N.) and spreading index (S.I.)--every sample was processed as follows. After the total volume (10 ml.) of fat free ethyl ether used to collect the material in our cylindrical receptacle had in a 10 ml. measuring flask slowly evaporated at 40øC., the residue was redissolved in 10 ml. of fat free petroleum ether. Under precautions necessary to avoid transfer of scales, etc. (6, 11), 5 ml. of this volume were used for gravimetric deter- mination of the lipid quantity,*t 3ml. for assaying the acid number and the remainder for assaying the spreading index. The A. N. was assayed in a manner similar to the procedure of Hodgson- Jones and Wheatley (12), who in turn rather closely followed the method described by Moyle, Baldwin and Scarisbruck (13). However, because of the much smaller lipid quantity obtainable from the different sites to be investigated separately, several modifications had to be introduced. Thus, for the titration it was found necessary to reduce the concentration of KOH in methanol from 0.005 N to 0.002 N.• Smaller volumes, more- over, of solvent (chloroform) and of indicator had to be employed. Briefly, we proceed in the following manner: The 3 ml. aliquot of the solution in petroleum ether is placed in a wide- necked 30 ml. Erlenmeyer flask and evaporated again at 40øC. After cooling, 2 ml. of chloroform and one drop of 0.04 per cent cresol red in methanol are added to the residue. The solution is carefully shaken. In order to remove the COs present a stream of gaseous nitrogen is carefully bubbled through the chloroform solution for thirty seconds prior to titra- tion. This is continued also through the period of titrating it must be done slowly to avoid volatilization. The titration out of a microburette (one drop equals 0.01 ml. of the KOH solution in methanol) likewise is carried out slowly, since neutralization and color change, as a rule, do not occur immediately. The turn from greenish-yellow to a reddish-yellow is the end point. The addition of one drop in excess produces a distinctly purple color. Under our laboratory conditions it is necessary to titrate about four "blanks" of chloroform, 2 ml. each, immediately prior to any assaying of samples. There are day to day variations of the blank titres from 0.02 to 0.03 or even 0.04 ml. of KOH, which must be deducted from the volumes required for neutralizing the solution under test. From time to time it has been useful to perform control titrations of' different known concentrations of stearic acid in chloroform. * TCY (Key Board) Balance, William Ainsworth & Sons, Denver, Colo., sensitivity 0.01 mg. t Weighing of the residue was performed in 6 ml. aluminum foil cups, 3 cm. in. diame- ter, "Crinkle Cups," Muller Paper Goods Co., Inc., Long Island City, N. ¾. it Prepared by courtesy of Joseph R. La Vieres, La-Mar Laboratories, Inc., New York, N. ¾.

90 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS z• o • ¸

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