Third International Congress of Phytopharmacy HE Third International Congress of Phytopharmacy m e t in TParis September 15 to 21, 1952. Abstracts of papers presented before Sections I and I1 on chemical, physical, a n d physicochemical studies are given hcre.
serve also for studying the retention of the alkaloid by plants t r e a t e j with insecticides. Determination of Aldrin in Agricultural Materials. S. 2. PERRY, LOUISLYKKEN, F. R. BROOKS, A. E. O’DOSNELL,A N D E. J. AGAZZI, Emeryville, Calif.
Polarographic Study of DDT. J. P R ~ ASD T D. BODIN,Vert-lePetit, France.
The merits of several different methods for determining the insecticide aldrin a t the level of 0.1 p.p.m. were discussed. A procedure was described for a nonspecific method based on a sensitive means for determining total halogen in microgram amounts. Results obtained with control crop samples containing known amounts of added aldrin were given. It was concluded that this method gives satisfactory results a t the desired level, provided the history of crop treatments is known and interferences can be overcome.
The influence of different factors on the form of the wave, its height, and the half-wave potential has been determined. These factors are: isomerism, hydrolysis, solvent, concentration in water, electrolyte, supports, etc. Partition Chromatographic Method of Assaying the Gamma Isomer of Hexachlorocyclohexane. N. B. VAN BUREN, United States.
To determine with sufficient accuracy the gamma content of a product containing a high percentage of gamma isomer of hexachlorocyclohexane, a relatively simple partition chromatographic method has been established by the Association of Official Agricultural Chemists in the United States. The method does not require elaborate and expensive apparatus and most normally equipped chemical laboratories can produce satisfactory and reliable results. The equipment used is a borosilicate glass partition column, a solvent evaporator, a blender, and some Erlenmeycr and yolumetric flasks as well as the usual laboratory equipment. Reagents are n-hexane, nitromethane, silicic acid, arid a dye solution (I-hydroxy-4-p-toluinoanthraquinone).
Some Applications of Phosphorus-32 to the Study of Systemic Insecticides. D. F. HEATH,Great Britain. The use of phosphorus-32 as a radioactive indicator in the study of organophosphorus systemic insecticides has made practicable m a n y researches which would have been very difficult or impossible to perform with only ordinary chemical methods of analysis. It is not only more sensitive and swift, but, as naturally occurring phosphorus does not interfere, much more specific. Methods involving the use of partition between immiscible solvents in analyzing plant macerates for systemic insecticides and their decomposition products were described. The general principles were illustrated by summaries of experiments performed to determine the rates of decomposition in plants of octamethylpyrophosphoramide and other systemic insecticides and the toxicities of their decomposition products, and to find a suitable method for the routine analysis for toxic residues of his-dimethylaminofluorophosphine oxide.
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Contribution to the Chromatographic Determination of Hexachlorocyclohexane. GRANGER, Salindres, France.
A practical process mas described, using 50 grams of silica by diverse operative techniques, chromatography in the presence of nitromethane on 0.05 gram of y-hexachlorocyclohexane, and chromatography in the presence of water on 0.2 gram of y-hexachlorocyclohexane. Applications t o the analy-is of various insecticidal products, in both powder and liquid form, vere given.
Preparation of Samples of Hexachlorocyclohexane in the Light of A N D -4. the Determination of Their Active Product Content. J. PRLT COLAS,Vert-le-Petit, France.
Promising Spectrochemical Method for Determining Chlorine in Insecticides and Other Materials. LAISHELENA DE P A I ~ AZETEDO, A SSo Paulo, Brazil, AND ALSTONW, SPECHT,Beltsville, Md.
Examination of the drying curves of different hexachlorocyclohexanes under varying conditions was discussed, and conclusions were drawn regarding the preparation of samples in the light of their analysis.
An emission spectrographic method has been developed for producing the calcium chloride band head at 5934 A., using an insecticide such as technical D D T , BHC, toxaphene, and aldrin as a source of chlorine and monocalcium phosphate as a source of calcium. This band head is produced by a special type of carbon electrode which provides for the simultaneous delivery of calcium and chlorine in the gaseous state to a direct current arc burning at 150 volts and 24 amperes. The lower limit of chlorine detection by this method is approximately 48 micrograms. An analytical curve derived from spectrograms produced by standard homogeneous mixtures of pure D D T and monocalcium phosphate indicates that it is possible to measure chlorine quantitatively in insecticides when the electrode charge contains between 48 and 120 micrograms of the element. Determination of Small Quantities of Nicotine in Biological Materials. Application to the Study of the Absorption and Elimination of the Alkaloid in Subjects Exposed. R. FABRE, R. TRUHAUT, AND CL. BOUDENE, Paris, France. Following Corcoran and his collaborators and Mme. GarreauPerdreau (1946) the authors have applied t o the determination of nicotine the color reaction which gives, with pyridine and certain of its derivatives, cyanogen bromide in the presence of an aromatic amine, such as benzidine (red-orange coloration). Several improvements have been brought about by operating at pH 5.3 in the presence of a suitable quantity of acetone. Not only is the sensitivity much increased, but because clear colored liquids are obtained, the photometric reading is greatly facilitated. For application to biological materials and especially t o urine, which constitutes the way of eliminating by far the most important part of the alkaloid, distillation by steam in an alkaline medium is used and the distillate is received in a weak hydrochloric medium. After extraction by ether to eliminate certain impurities, the photometric determination is carried on. This method permits observation of subjects exposed to the absorption of nicotine. I t is applicable t o vegetable materials and may
New Analytical Methods for Plant Protective Materials.
M.
MAY,Berlin, Germany. Ever since inorganic insecticides and fungicides have been utilized in phytopharmacy in the form of products for pulverization or powdering, standard methods of examination based on the study of physical or chemical properties, which have been the object of numerous publications, have been employed, But with the discovery or invention of active organic materials, and their utilization in the form of sprays or mist, the needs have increased especially for the definition of physical qualities. S e w methods of assay have become indispensable. New methods were presented, with examples of (1) esters as insecticides, (2) wettable colloidal sulfurs as fungicides, and (3) hexachlorocyclohexane as a product for the treatment of sols. 1. Examination of the initial action and persistence by the Drosophilzis test. Properties of emulsions in relation to the chemical stability of active matter (hydrolysis) and wetting power (measure of superficial tension using a torsion balance). 2 . Microscopic measurement of the size of particles. Method of studying sedimentation. Assay of adherence (persistence tested by the effect of artificial rain). Distribution on plants, advantages and disadvantages. 3. Influence of the density of gas on the method of application. Different forms of application according to whether or not the gas IS dense (hexachlorocyclohexane lighter than air may be buried in the soil, ester heavier than air may be utilized in sprinkling).
Preservation of Insecticides during Long Periods of Storage. P. L A P ~ R O U SLyon, E , France. More frequent publication of the results of tests of preservation of antiparasitic products during storage would be desirable. The case of rotenope was studied as an example. The results do not -how a
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particularly rapid destruction of the active principle. A complete review bearing on these products and a clear statement of data already obtained should be prepared. New Process for Obtaining Insecticide Aerosols. J. BOUSCRARAIN, Paris, France.
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The authors described a new process for obtaining insecticidal aerosols. The process is based on the carrying over of organic products as vapor by azeotropic distillation. Indications of the physical structure of the particles were given. The activity of the aerosols on different insects has been studied. Measurements have been made in confined space on flies, domestic crickets, weevils, and caterpillars. The practical efficacy of aerosols has been studied on the Tineidcs and in the forest on oak and pine caterpillars. New Type of Concentrated Pesticides.
not contain phytotoxic or inflammable solvents or other noxious auxiliary material. Products of this type have been employed in actual practice or in field trials with success in several cases, by both the high-volume and the low-volume technique: with D D T for the control of cotton jassids (Sudan), Colorado beetles and larvae (Netherlands), and tsetse flies and malaria mosquitoes (Uganda) ; with benzene hexachloride against apple saw fly, cabbage weevils, cabbage pollen beetle, and cabbage gallmidge in the Netherlands; with both D D T and benzene hexachloride as sheep dip against Psoroptes scab: with T M T D against apple scab: and with the ammonium salt of DNOC as aphicide on apple trees in early spring, and as a weed killer.
Applications of Ultrasounds to Certain Problems of the Phytopharmaceutical Industry. R.-G. BUSNEL,Jouy-en-Josas, France.
J.-R. DE JONG AXD N.VAN
TIEL, .4msterdam, Holland.
As the existing forms of pesticides have certain drawbacks, a new form of product has been developed. The essential feature of this type of product is that, in addition to mineral oil and water, it contains a high percentage of the toxicant (40 to 50% by weight) in the form of very small solid particles; it has the consistency of a creamy paste and is easy to pour and t o dilute with water. Many solid toxicants can be brought into this form. Extensive biological investigations have shown that the most important advantages of these products are: The toxicant, in the diluted spray, has a low rate of sedimentation. There is no loss of activity due to penetration into porous substrate, which is the case with dissolved toxicants. The toxicant adheres tenaciously to the substratum. The deposited toxicant has a great resistance to rain. T h e residue of the spray has a high initial toxicity. The product does
The laboratory results of the application of ultrasounds to certain problems of the chemistry of emulsions and colloids indicate that the technique of ultrasonic vibrations may eventually be extended to industry and especially to phytopharmacy. The well known dispersive property of ultrasounds may be applied to the production of nonmiscible liquids, to the dispersion of organic or metallic compounds, to the precipitation of colloids, to depolymerization, and to the formation of aerosols. The mechanisms of action are beginning to be well known, but the physical factors (wave length, wave system, intensity) must be studied in each case. Certain recent applications of ultrasounds are: formation of aqueous suspensions of D D T and hexachlorocyclohexane; emulsion of oils, mercury, and lead in water; production and dispersion 01 organic or metallic ions by ultrasonics in the course of electrolysis(copper) ; aerosols of aqueous solutions or oil; precipitation of colloids (sulfur).
Eighth Southwest Regional Meeting HE Eighth Southwest Regional Meeting of the AMERICAX 'CHEMICAL SOCIETY was held in Little Rock, Ark., December 4 to 6, 1952, with t h e Central Arkansas, South =Irkansas, and University of -4rkansas Sections as hosts. Abstracts of papers of particular interest t o analytical chemists are given here. Prog r a m chairman is Edgar Wertheim, Department of ('hemistry, Vniversity of -4rkansas, Fayetteville, .4rk. Spectrophotometric Determination of Aliphatic Sulfides. HASTINGS, Humble Oil & Refining Co., Baytown, Tex.
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A real need exists for rapid and sensitive analytical procedures for the sulfur compound types present in petroleum and petroleum products. I n response t o this need, development work has been carried out on a new procedure for the determination of aliphatic sulfides based on the intense absorption shown by the iodine complexes of these compounds a t 308 mp. It has been found that iodine forms complexes wit,h aliphatic sulfides (both acyclic and cyclic) having absorptivities a t 308 m p in the league of 50 liters per gram cm. (based on the sulfide sulfur content) for a constant iodine concentration of 0.1 gram per liter. This coefficient is relatively constant for nearly all the sulfides examined. A light-dark equilibrium phenomenon which was observed was discussed and a procedure was given which is sensitive t o 1 p.p.m. of sulfide sulfur under ideal conditions.
Use of Ethylenediaminetetraacetic Acid in Polarography. CECIL H. HALEA X D M~RGIEN. HALE,Southeastern Analytical Chemists, Austin, Tex. The ability of ethylenediaminetetraacetic acid to form stable complexes with a large number of metal ions makes it useful for preventing the interference of many of these ions in polarography. I n a solution alkaline with tetrabutylammonium hydroxide, ethylenediammetetraacetic acid prevents the polarographic reduction of calcium, magnesium, barium, aluminum, cobalt(II), nickel, cadmium, nianganese(II1) , chromium(III), and zinc ions. The reduction potentials of sodium and potassium are unaffected, whereas those of lead, copper(II), and iron(II1) are shifted to more negative values. Ethylenediaminetetraacetic acid itself is not reducible in tetrabutylammonium hydroxide solution. As an illustration of the application of this coniplexing agent, alkali metal impurities can be determined
polarographically in calcium, magneaium, a i d barium salts. 111 the absence of ethylenediaminetetraacetic acid, even small amounts of calcium, magnesium, or barium ions interfere with the polarographic determination of sodium or potassium. Polarographic Characterization of p-Nitroacetophenone and Related Compounds. T . S. BURKHaLTER .4ND BOBBYG. MESSICK, Texas -1.Br M. College, College Station, Tex. The polarographic properties of p-nitroacetophenone, p-bromoacetophenone, p-aminoacetophenone, and pnitrophenacylbromide were reported. The order of reduction of the various groups, effects of pH upon the half-wave potential and diffusion currents, the number of electrons involved in the reduction, and the probable reversiliility of the reactions have been determined. All reductions are apparently thermodynamically irreversible. 'With the exception of nitro reduction below a p H of 4, all half-wave potentials are independent of pH. The keto reduction exhibits two waves above a p H of 4 when the nitro group is para but only one wave for the bromo or amino substituent. Identification of Polymers by Infrared Analysis of Their Pyrolysis Products. PAUL F. KRUSE,JR.,A N D WILLIAYB. WALLACE, Sandia Corp., Albuquerque, N. M. Analysis of pyrolysis products of rubber and plastics materials by infrared absorption spectroscopy was presented as a method for more rapid, reliable, qualitative identification of these materials than color tests, spot tests, and chemical analytical procedures. A variety of natural and synthetic rubber and thermoplastic and thermoset plastics were pyrolyzed for 2 minutes a t 830' to 8700O F. into carbon tetrachloride. The infrared spectra of the pyrolyzates were obtained, compensating for the solvent. The spectra of the pyrolyzates from several samples of each of the materials were found to contain unique features which were reproduced closely. Examples of bands which were useful in identifying the parent materials included: GR-S, 1600, 1490, 907, and 695 cm.-l; natural rubber, 889 cm.-*; Butyl, 1212 em.-', and a doublet a t 1372 and 1360 cm.-1; Buna-N, 1740 and 1250-1000 cm.-l; Kel-F, 1785 cm.-1 Spectra-structure correlations were discussed, and the absence of bands was shown to be often useful. Slides of the spectra of pyrolyzates of GR-S, natural, natural and GR-S mixture, Butyl, neoprene, and Buna-N rubber and Kel-F, vinylite, and diallyl phthalate plastics were shown and discussed t o illustrate the method.
