V O L U M E 21, NO. 7, J U L Y 1 9 4 9
781 dropping mercury electrode, has been esamined rTith a platinum electrode. These studies \Till be reported later. Solid electrodes simplify analyses in solutions containing hydrofluoric acid because i t is possible to use a plastic cell to hold the solution and to coat, with wax, the glass in which the platinum electrode is embedded. It appears plausible to expect a solid electrode to be useful for studies in liquid ammonia and similar solvents. ACKYOWLEDGXIEYT
The authors are indebted to D. E. Ehrlinger for making some of the measurements reported in this paper and to Kathryn Odom for helping to prepare the manuscript. Work performed for Atomic Energy Commission under Contract K-35-058 eng. 71 r5ith Nonsanto Chemical Company and Contract 7405 eng. 26 viith Carbide and Carbon Chemicals Corporation. LITERATURE CITED
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Figure 6. Polarographic Maximum Obtained w i t h rotated p l a t i n u m microelectrode i n solution containing 5.0 X 10‘6 M AgNOa i n 0.1 M KNOI a n d 0.01 % g e l a t i n a t pH 4.0. Rate of polariaation, 4.65 m v . / s e c .
mum was undoubtedly connected with the discharge of silver, i t was probably the result of a brief discharge of hydrogen. Curve I1 in Figure 4 shows a similar but less striking masimuni which was probably due to osygen evolution. Applications. The fact that polarographic procedures offer a rapid method for the determination of normal and formal (13) potentials has been known for some time ( 2 ) . If a solid platinum electrode is used instead of a dropping mercury electrode for studying deposition reactions, calculations can be simplified because there is no longer a need for considering displacement of the wave as a result of amalgam formation. The recording of curves for ions other than silver has been tested and found to be as satisfactory as for silver. Thus, it is possible to use the usual polarographic recording technique to make qualitative and semiquantitative analyses for ceric, permanganate, and dichromate ions whose analyses have heretofore been complicated by the spontaneity of their reactions wi h mercury. Similarly, oxidation of hydrazine and chromic ion, which cannot be performed because of the anodic dissolution of the
Harris, E.D., and Lindsey, -4. J., Sature, 162, 413 (1948). Kerlinger, H., in Kolthoff, I &I., and Lingane, J. J., “Polarography,” p. 155, New York, Interscience Publishers, 1941. and Kolthoff, I. M., J . Am. Chem. Soc., 61, 3344 Laitinen, H . .i.,
(1939). J . Phys. Chem., 45, 1061 Laitinen, H. h.,and Kolthoff, I. &I., (1941). Ibid., 45, 1079 (1941). Latimer, W.M.,“Oxidation Potentials,” X e w York, PrenticeHall, 1938. Matheson, L. A , , private communication. Matheson, L. A., and Nichols, K.,Trans. Am. Electrochem. Soc., 73, 193 (1938). *Miller, S. D., Trudy Vsesoyicz. Konferentsii Anal. Khim., 2, 551 (1943). -Muller, 0. H., 110th Meeting, AMERICAK CHEMICILSOCIETY, Chicago, Ill., Sept. 9 to 13, 1946; J . Am. Chem. SOC.,69, 2992 (1947). Randles, J. E. B., AnaZgst, 72, 310 (1947). Skobets, E. M., and Kacherora, S. A.. Zaaodskaya Lab., 13, 133 (1947). Swift, E. H., “System of Chemical Analysis,” p. 50, New York, Prentice-Hall, 1940. Walen, K.J., and Haissinsky, If., J . phys. radium (7), 10, 202 (1939). Zlotowski, I., Roczniki Chem., 14, 640, 651, 666 (1934). RECEIVED1Iay 17, 1948. Presented in part before t h e E a s t Tennessee Section of the AMERICAN CHEXICAL SOCIETI. Knoxville, Tenn., J l a y 24, 1947, and later in more detail before t h e Division of Analytical and Micro SOCIETY, Chemistry a t t h e 113th Meeting of the ERICAS AS CHEMICAL Chicago, Ill.
Chemicotoxicological Examination ’of Foods A Systematic Procedure N. I. GOLDSTONE, D e p a r t m e n t
of H e a l t h , C i t y of New York, A‘. Y .
A systematic procedure is presented for the isolation and detection of 26 common toxic substances, comprising the four groups: volatile, metallic, alkaloidal, and nonalkaloidal. Sensitive analytical methods and confirmatory tests fitted into a methodical sequence are described in detail.
T
HE branch of the science of toxicology that deals with the isolation and detection of poisons is divided into two major classifications: the forensic, involving a crime either premeditated or accidental, to which scientific principles first began t o be applied during the eighteenth century; and industrial poisoning, the object of aggressive social and scientific attack only for the past 50 years. A number of adequate tests (3-5, 8-10, 14-22, 25-27, 30) have been published in both categories, and these include precise chemical methods for the detection and estimation of a large number of toxic substances. I n the forensic field the emphasis is naturally placed on the examination of the cadaver a n d body organs, with a chapter incidentally devoted to a discus-
sion of the detection and identification of poisons in foods and related products. The latter subject is constantly receiving more attention in connection with the growing interest in the related field of trace elements in food ( 7 ) . Most textbooks present the subject in a tabular form incorporated within the framework of the particular system of classification preferred by its author, describing the various members of each group with their properties and physiological responses, in addition to analytical methods for detection and estimation. But nowhere in the literature is there to be found a simple, comprehensive, and systematic analytical procedure whereby the chemist without any considerable experience in this particular field is
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ANALYTICAL CHEMISTRY
enabled to proceed in an orderly manner to separate and identify toxic substances. In large cities cases of suspected food poisoning are daily occurrences, and because community laws often make it obligatory on the part of the attending physician to report such cases to the public health authorities, a lahoratory must be efficiently main-
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OUTLINE
GRAPHIC $ample
tamed for the analysis of the foods involved, often with the requirement that numerous samples be examined concurrently The author has worked out a simple and sensitive procedure for chemical analysis which may prove of interest to food and health control laboratories, consultants, and perhaps also the industrial lahoratory which will sooner or later he called upon to investigate
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