PANTOTHENIC ACID 



6. ESTIMATION OF PANTOTHENIC ACID 



Attention has already been directed (page 348) to early attempts 

 to estimate the " filtrate factor " by its effect on the growth of rats 

 and chicks, but it is doubtful if such methods are sufficiently specific 

 to do more than give very approximate results, although T. H. Jukes ^ 

 used chicks to measure the pantothenic acid contents of a variety of 

 foodstuffs, and J. D. S. Bacon and G. N. Jenkins ^ described an 

 apparently satisfactory method of assay, using rats. 



Up to the present no chemical method of estimation has been 

 proposed, although J. J. Lingane and O. L. Davis ^ found that panto- 

 thenic acid was reduced at the dropping mercury electrode. Its 

 polarogram was not sufficiently well defined, however, for the polaro- 

 graphic method to be used for its estimation. 



ZViicrobiological Methods of Assay 



The only satisfactory methods of assay so far published have been 

 microbiological methods, and these have been extensively used. 

 Among the first micro-organisms to be tested for this purpose were 

 Streptococcus lactis, Bacillus hrassicae and Propionibacterium pento- 

 saceum,* but these failed to give satisfactory results. The first success- 

 ful method was devised by Pennington et al.,^ who used Lactobacillus 

 helveticus, the organism introduced by Snell and Strong for the esti- 

 mation of riboflavine (page 157). The turbidity of cultures grown on 

 a suitable medium or the amount of lactic acid produced was propor- 

 tional to the amount of pantothenic acid added. Strong et al.^ 

 described a similar method, using the same organism, whilst H. R. 

 Skeggs and L. D. Wright "^ developed an analogous method with 

 L. arabinosus as test organism. M. J. Pelczar and J. R. Porter ^ 

 used Proteus morganii, the growth of which on a suitable medium was 

 proportional to the amount of pantothenic acid present. The amount 

 of growth was measured by determining the bacterial nitrogen or by 

 measuring the change in pK or the increase in turbidity. The method 

 was claimed to be highly specific, but the organism also responded to 

 pantoic acid. L. helveticus was the organism used by M. Tandy and 

 D. M. Dicken ® in the method developed by them for the assay of six 

 members of the vitamin B complex using the same basal medium. 

 Modifications to the medium of Pennington et al. were suggested by 

 J. L. Stokes and B. B. Martin ^® who found that merely increasing the 

 amounts of glucose and sodium acetate increased the production of 

 acid, and by A. E. Tight and M. F. Clarke. ^^ Good agreement was 

 reported by Hoag et al.^^ for results obtained with L. helveticus and 

 L. arabinosus, but the response was greater and more rapid with the 

 latter ; growth was measured either turbidimetrically after fourteen 



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