POLORAGRAPHIC TECHNIQUE 



280 



POLAROGRAPHIC TECHNIQUE 



mit dem Polarographen, Berlin: Verlag 

 von Julius Springer, 1937, 34-47. 



There are several American made 

 polarographs which automatically re- 

 cord current-voltage curves (polaro- 

 grams). These instruments have stim- 

 ulated research in the field and have 

 simplified the measurements consider- 

 ably. The following companies make 

 self-recording polarographs: E. H. 

 Sargent and Co., 155-165 East Superior 

 Street, Chicago 11, 111.; Leeds and 

 Northup, 4912 Stenton Avenue, Phila- 

 delphia, Pa.; Rutherford Instrument 

 Co., 8616 Georgia Avenue, Silver 

 Springs, Md. Manual recording 

 polarographs are also made by Fischer 

 Scientific Co., 2850 S. Jefferson Ave., 

 St. Louis, Mo. and E. H. Sargent and 

 Co., 155-165 East Superior St., Chicago, 

 11, 111. 



Training in the polargraphic method 

 of analysis is best achieved by working 

 with the instrument under supervision 

 of an expert, or by taking a course in 

 analytical chemistry in which the bases 

 of the method are taught. The latter 

 training can be obtained at the Chem- 

 istry Department of the University of 

 Minnesota, Minneapolis, Minn., or at 

 Harvard University, Cambridge, Mass. 



Polarographic analysis has been found 

 useful in many fields of endeavor: 



Vitamin B (Thiamin). Lingane, J. 

 J. and Davis, O. L., J. Biol. Chem., 



1941, 137, 567-574 found that this vita- 

 min gave a well defined wave at —0.25 

 volt (v.s. the saturated calomel elec- 

 trode in 0.1 N KCl). The method has 

 not been applied to natural products. 

 Vitamin B2 (Riboflavin) has been found 

 to be reducible by the same investiga- 

 tors (Lingane and Davis, Ibid). 



Nicotinic Acid and Nicotinamid. 

 Nicotinic acid is reducible in 0.1 N 

 NaHCOs, Shitkata, M. and Tachi, I., 

 Bull. Agr. Chem. Soc. (Japan) 1927, 

 3, 95-96. A detailed investigation of 

 the polarographic behavior of nicotinic 

 acid and related compounds has been 

 published by Tompkins, B. C. and 

 Schmidt, C. L. A. (Univ. Calif. Pub. 

 Physiol. 1943, 8. 229-247). 



Pantothenic acid is also reducible 

 (Lingane, J. J. and Davis, O. L., Ibid.). 



Vitamin C has been determined in 

 fruits and vegetables polarographically 

 by Gillam, W. S. (Indus, and Eng. 

 Chem. Anal. Ed., 1945, 17; 217-220). 



Vitamin E and related compounds 

 have been extensively investigated by 

 Kolthoff and coworkers, see Smith, 

 L. I., Kolthoff, I. M., Wawzonek, S. 

 and Ruoff, P. M., J. Am. Chem. Soc, 



1942, 64, 447-451; 644-648. This class 

 of compounds was oxidized having half- 



wave potentials of approximately 0.1 

 to 0.2 volt. 



Vitamin K-Vitamin Kb is also re- 

 ducible at the dropping mercury elec- 

 trode, see Knoblock, E., Collection 

 Czechoslov Chem. Commun., 1949, 14, 

 508-531. 



Folic acid can be determined polaro- 

 graphically in small amounts in tablets, 

 see Mader, W. J. and Frediani, H., 

 Amal. Chem., 1948, 20, 1199-1201. 



Steroids and Related Compounds. 

 Steroids such as testosterone, pro- 

 gesterone, pregnenol-17-one-3, desoxy- 

 corticosterone, etc. which have a car- 

 boxyl group conjugated with a double 

 bond are reducible (Eisenbrand, J. 

 and Picher, H., Zeit. Physiol. Chem., 

 1939, 260, 83-99). The reaction prod- 

 ucts of 17-ketosteroids with Girard's 

 Reagent T (trimethyl acethydrazide 

 ammonium chloride) make the method 

 more general in scope (Wolfe, J. K., 

 Hershberg, E. C. and Fieser, L. F., 

 J. Biol. Chem., 1940, 136, 653-687). 



Minerals. The polarograph is ideally 

 suited for the determination of minute 

 amounts of most of the metals with the 

 exception of the alkali and alkali-earth 

 metals (Kolthoff, I. M., and Lingane, 

 J. J., Ibid.). 



Proteins. Very few pure proteins 

 have been studied polarographically. 

 Proteins containing sulphydryl groups 

 or — S — S — groups can be determined 

 and their purification followed by the 

 shape of the catalytic reduction waves 

 (Carruthers, C, H. Biol. Chem., 1947, 

 171, 641-651). Proteins and polypep- 

 tides containing cystine or cysteine, 

 when dissolved in suitably buffered 

 cobalt solutions, produce a catalytic 

 reaction during electrolysis at the 

 dropping mercury electrode (Brdicka, 

 R. Collection Czechoslov. Chem. 

 Commun., 1936, 8, 366-376). This ob- 

 servation was used by some investiga- 

 tors as a test for cancer since the blood 

 sera of normal individuals and of 

 persons suffering from cancer revealed 

 significant differences in the height of 

 the catalytic waves (Brdicka, R., 

 Nature, 1937, 139, 330; 1020-1021). 

 However, this test proved to be non- 

 specific (Rusch, H. P., Klatt, T., 

 Meloche, V. W., and Dirksen, A. J., 

 Proc. Soc. Exptl. Biol. Med., 1940, 44, 

 362-365). 



Amino acids. Amino acids, with the 

 exception of cysteine and cystine which 

 give catalytic waves in buffered cobalt 

 solutions, are not reducible. 



Many other types of organic com- 

 pounds are also reducible. For ex- 

 ample, carcinogenic hydrocarbons such 

 as 3-methylcholanthrene, 3-4,benzypy- 



