ANNUAL REPORT, 1944-45 47 



Red Squill Research. (L. R. Parkinson and F. P. Griffiths.) Laboratory tests 

 have confirmed the fact that red squill (a raticide) of low toxicity may be forti- 

 fied with a concentrate containing the toxic principle of red squill in order to 

 provide a satisfactory commercial product. Such red squill preparations should 

 prove to be very effective for rodent control. 



Vitamin D Milk Investigations. (L. R. Parkinson and F. P. Griffiths.) Studies 

 have been continued on the fortification of fluid milk with vitamin D. During 

 the past year 173 samples have been assayed and all but five contained the desig- 

 nated amount of vitamin D. Data obtained during the past three years indicate 

 that the present methods of fortification are reliable and that the producers of 

 vitamin D milk are making every effort to provide a standardized product. 



DEPARTMENT OF HOME ECONOMICS NUTRITION 

 Julia O. Holmes in Charge 



A study of Methods for Determination of Riboflavin. (A. W. Wertz, B. V. 

 McKey, K. O. Esselen, and J. O. Holmes.) In a fluorophotometric assay of the 

 riboflavin content of foods, conducted last year, it was discovered that the recom- 

 mended procedures were not entirely satisfactory with highly pigmented foods 

 such as kale and baked beans. A comparison was therefore made of the biological, 

 microbiological, and fluorophotometric methods currently used in assays for 

 this vitamin. Four foods were studied: beans, milk, kale, and fish. Good agree- 

 ment between certain modifications of these three methods was found when 

 applied to milk, kale, and mackerel. The microbiological method appeared to 

 give low values for baked beans. 



On the basis of the good agreement between the three types of assay procedures, 

 it was concluded that one currently recommended step in the fluorophotometric 

 procedure was responsible for the introduction of a marked error in assay values; 

 namely, the manner in which the comparison was made between the fluorescence 

 of the food extracts and the standardized solution of riboflavin. In every instance 

 in which the fluorescence of the standard was determined apart from the food 

 extract, erroneously low values were obtained; in those instances in which the" 

 riboflavin standard was added to the extract, values were obtained which agreed 

 well with those obtained by the biological method and, with the exception of 

 those for beans, with the microbiological method. The conclusion therefore has 

 been drawn that it is imperative that the standardized solution of riboflavin be 

 added to the food extract. 



Both the fluorophotometric and the microbiological procedures contained 

 manipulations found to be unnecessary when applied to the foods studied. The 

 enzymatic digestion of the foods appeared to be unnecessary. In the micro- 

 biological procedure, the removal of fat from the extracts and the addition of 

 an irradiated extract to the blank and to the standard curve did not affect the 

 values for riboflavin. In the fluorophotometric method the use of florosil on 

 which to absorb the riboflavin conferred no advantages. This was true also for 

 the procedure involving the oxidation of the extracts with KMn04. 



The riboflavin content of frozen baked beans, blanched kale, and steamed 

 fish did not decrease over a six-month period. 



Relationship Between Calcification of Eggshell and Carbonic Anhydrase 

 Activity. (Marie S. Gutowska and U. C. Pozzani.) Previous study in this labora- 

 tory has shown a direct relationship between the activity of carbonic anhydrase 

 in the shell gland of the hen and the calcification of the eggshell. The administra- 



