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ANALYTICAL CHEMISTRY
sludge digestion. Analytical procedures were described for the determination of some of the most troublesome of these ions arid radicals, including copper, zinc, chromium, iron, and cyanide, by the application of new techniques.
Quantitative analysis is the division of chemistry dealing with the determination of the amount of one or more desired constituents in a given sample. The methods used range from the simplicity of applying a hydrion test paper to all that is involved in making a complete analysis of a granite rock. Ultimately, any Determination of Metals in Industrial Wastes. H. GLADYS procedure consists of chemistry, if any is involved, and always of physics. SWOPE, rlllegheny County Sanitary Authority, Pittsburgh, Pa. The chemistry includes whatever transformations are necesThe analyses considered were those for iron, copper, chromium, sary to get the system ready for measurement. Common unit vanadium, and cyanide. operations are fusion, dissolution, complexation, and separation. Two main difficulties arise in analyzing industrial wastes, the The last operation may be volatilization, precipitation, electrosmall amounts, many times less than 1.0 part per million, and the deposition, or extraction. For such processes some modern appamany unknown possible interfering ions. No absolutely foolratus, such as Podbielniak stills, are fairly complicated. proof method was given for any specific element, since not ever Finally comes measurement, the specific method used being known method for the ions was tried, but the difficulties whicg preferably that best suited to the situation at hand. Xothing is arose and the method of circumventing them were discussed. In much simpler, nor more common, than the hydrometer seen a t most cases 1 to 2 liters of the sample must be concentrated to 100 every gasoline filling station. Probably nothing is more complito 500 cc. in order even to detect the presence of certain ions. cated than the latest mass or recording emission spectrometer. Small amounts of iron (less than 5 p.p.m.) were determined Teachers today face a real problem. With only limited time spectrophotometrically using the o-phenanthroline method. and facilities at their disposal, what should be included iri the one Fifty cubic centimeters of the sample were digested and evaposhort course which is now being given to most chemical graduates? rated to dryness with concentrated sulfuric acid, then boiled with Samples cover the whole range of natural and synthetic materials. 3 N hydrochloric acid before adding the hydroxylamine hydroEvery element in the periodic table, including their isotopes, must chloride and o-phenanthroline and adjusting the pH to between 3 be anticipated until proved absent or insignificant. The kinds and 8. Copper, chromium, and vanadium had to be removed, if of possible combinations of these elements are almost endless. present. For larger amounts of iron the Zimmermann-Reinhardt To meet this situation, what morking knowledge of chemistry method was used. Copper was determined electrolytically, the original waste being should be attempted? Then measurement means physics. Here concentrated from 2000 to 250 cc. If less than 1.0 p.p.m of copper one finds an ever-increasing variety and complexity of instruwas present colorimetric methods would have to be used. ments involving especially mechanics, optics, and electronics. Chromium was determined by concentrating 1 to 2 liters of For what training in this direction is the teacher of quantitative sample to 250 cc. and following the procedure given on p. 152 of analysis responsible? What training do industrialists want in Griffin’s “Technical Methods of Analysis” (RfcGraw-Hill), 1927 our graduates? K h a t is possible in the ordinary colleges these edition, except that no phosphoric acid was used and the sample days7 was titrated with standard ceric sulfate instead of potassium permanganate. Vanadium was determined in samples which might also contain Analytical Techniques. A Course in Quantitative Analysis for chromium; therefore these were run on the same sample. ConUniChemical Engineering Students. CARLJ. EXGELDER, centrated sulfuric acid and dilute nitric acid were added to a versity of Pittsburgh, Pittsburgh, Pa. suitable portion of the sample and the solution was boiled. The paper described a new type of course of instruction in quanStrong potassium permanganate was added dropwise and boiling titative analysis for sophomore chepical and metallurgical engicontinued for 20 minutes. The manganese dioxide was filtered neers, now being given a t the University of Pittsburgh. The off and sulfuric acid (1.5 sp. gr.) added. The solution was then main purpose is to acquaint the student engineer with the methcooled to 5” C. and an excess of ferrous sulfate added. Titration ods, devices, instruments, and principles employed in an anawith standard ceric sulfate was then carried out. Ammonium lytical laboratory, with more emphasis on treatment of data and hydroxide was added slowly, then sodium acetate and the solution computations than on precise manipulation and extreme accuracy heated to 50’ C., and titrati6n again performed with ceric sulfate. of results. The course covers for one-half the semester two simple This latter titration gives the amount of vanadium present. gravimetric and three volumetric determinations, designed t o Cyanides were determined by the modified Liebig method. familiarize the student with the handling of a balance and voluCollection and preqervation of the original sample are important. metric apparatus and acquaint him with chemical factors, titers, and normalities as they are applied to factor-weight samples and SYMPOSIUM ON MODERN COURSES IN ANALYTICAL percentage-volume solutions. The second half of the course CHEMISTRY covers mainly instrumental analysis in which colorimetric, electrolytic, gas, and coal analysis are introduced together with the Quantitative Analysis, Perspective and Problem. M. G. MELuse of a pH meter for potentiometric titration. LON, Purdue University, Lafayette, Ind.
Metropolitan Microchemical Society of New Y ork L. T. HALLETT,Associate Editor
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H E Metropolitan hIicrochemica1 Society of New York held its third annual symposium February 27 to 28. onebundred chemists listened to an interesting and varied Program styled for those whose work involves the handling and analysis of small samples. Recent Developments in Microscopy. KURT J. HEIKICKE, Research Engineering Division, Bausch Lamb Optical co,, Rochester, S.Y. The possible use of ultraviolet as a source of light in microscopy 1904, but the difficultyin developing discussed as early proper lenses for focusing has delayed its applicalion. since that time proper lenscbs and more efiicient fluorescent Screens and light sources have been developed, and in the near future ultraviolet microscopy will find wide application. In this type of niicroscopy the monochromatic light is passed through a specimen and a system of lenses, to a photographic plate or a phototube giving resolution to specimens which absorb in the ultraviolet range.
Phase microscopy is essentially converting phase differences created by the specimen into brightness differences clearly discernible by the eye. I n this type of microscopy a green or blue light is passed through the specimen, specially developed quarts lenses, and a phase plate to the eye or other receptor. The light, as it passes through the specimen, may be thrown a part of a wave length out of phase, giving resolution which cannot be obtained b y ordinary‘micros6opy.- By using phase microscop quartz placed in a liquid of the same refractive index is clearg discernible. Other examples of better resolution were shown by comparing mouth epithelial cells and the sediment in urine with an ordinary and a phase microscope. Further development of chemicals fluorescing in the infrared for focusing srceens is being carried out. The discovery Of these chemicals will open UP a new field of infrared photomicrography. The Application of Infrared Spectroscopy. KONRADDON . D . , Department of Hormone Chemistry, SloanKettering Institute, Memorial Hospital Cancer Center, New York, K.Y.
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For some time there has been a need of a niethod or an instrument for characterizing steroid metabolites found in the urine. Since about 1942, infrared spectrophotometry has been successfully used for this purpose. I n the study of urine from well and diseased persons, it has been necessary to study small amounts (50 micrograms) of the isolated steroids. Infrared study of this small quantity of material has directly contributed to the discovery of new steroid metabolites, quantitative estimates of known steroids, and the determination of position of functional groups, which has led to the exact development of the structures of certain steroids. Isolation of the steroids from the urine has been made by chromatographic absorption, and an infrared absorption library of about 450 references has been built up. The wave-length absorption of the functional groups has been well established, so that the position of the functional groups of isolated steroid metabolites can be readily established. The bends caused by minimum absorptions, called the fingerprint regions, have also been found important in the characterization of the steroid by pointing out minor differences in structure and purity. Slides were shown to compare the infrared absorption of steroids isolated from urine with known steroids. Infrared study of urinary steroid metabolites has led to the isolation of a steroid associated with practically all cancer cases. Experiences with Microchrornatography. RICHARD J. BLOCK, Department of Physiology and Biochemistry, New York Medical College, Xew York, h’. Y. Paper chromatography for the separation of amino acids, sugars, and fatty acids became widely used after the publication of “Qualitative Analysis of Proteins. A Partition Chromatographic Method Using Paper” in 1944 by Consden, Gordon, and Martin. I t s sensitivity and usefulness are indicated by the possibility of identifying approximately 20 amino acids in the hydrolyzate of 0.2 to 0.4mg. of hydrolyzed protein. I n this method the paper functions only as an inert support for the two solvents and has the advantage over silica gel that it has no retentive action over the moving amino acids. Separation of the amino acids takes place because of the different relative solubilities of each amino acid between the water, which is held by the cellulose fiber, and a solvent not miscible with water, which is allowed to flow slowly up the filter paper past the spot which contains the amino acid mixture. The separation is carried out in an ordinary, rectangular aquarium, after slight modification, on large sheets of filter paper. A chromatograph may be either one- or two-dimensional. Aft,er se aration, the acids are identified by treating the paper chemicayly to produce a color characteristic of each amino acid. In recent work, rats have been fed radioactive iodine and the protein hydrolyzate of the particular tissue has been separated chromatographically. The radioactive amino acid was t’hen determined chromatographically by cutting the chromatograph into strips and placing the strips in a Geiger counter. Statistical Methods in Analytical Chemistry. JOHX MAKDEI,, National Bureau of Standards, Washington, D. C. A statistician is usually consulted during the preparatory stage of an experiment if statistical treatment of the data is to be successful. After determining the water-absorptive tendency of synthetic rubber a t the Bureau of Standards recent’ly, the question arose as t o whether the error involved was due to combined errors of measurement or t o differences between the samples removed from several batches of rubber. The 32 data were treated statistically, and it was shown that the error of measurement was small compared to the difference in the samples of rubber from batch to batch. The validity of Beer’s law for the ultraviolet absorption of a solution of GRS rubber in methyl cyclohexane was studied. After plotting optical density vs. concentration of the 22 measurements (eleven on two consecutive days), the question arose as to whether the slight deviat,ion of the data from a straight-line plot was due to experimental error or was a true deviation. After statistical treatment of the data by regression analysis, it could be stated that the data did not satisfy Beer’s law, although by inspection or line fitting, one might be led to the conclusion that the data did satisfy Beer’s law, Applications of the Automatic Recording Spectrophotometer.
E. I. STEARNS,Calco Chemical Division, American Cyanamid Co., Bound Brook, N. J. The General Electric automatic recording spectrophotometer can be adapted for use in a number of broad problems for which it was not originally designed if certain modifications are made to the instrument and t o the sample holders normally provided.
281 A certain dye, when applied to TI-OO~, dyed the strand of wool but did not have light- or wash-faaness. When the dye was treated with sodium dichromate, the dye on the wool fiber became light- and wash-fast. The spectrophotometer was used to follow this reaction by placing the wool on a specially designed rotrtting drum and measuring the light reflected from the rotating sample. This gave a more accurate measurement of the color than if the color was measured a t any given part of the fiber. The alcohol concentration of rye whisky has been quantitatively determined by comparing the absorption of the alcohol in rye whisky to that of a sample of known alcohol concentration. The use of the instrument t o determine a reaction rate was illustrated by following the inversion of cane sugar by the spectrophotometer. A special cell v a s designed and placed in the instrument, and the inversion rate conveniently determined by absorption of the inverted sugar. The reflectance of printing inks has been determined by smearing samples of ink on the inner side of a right-angle prism and placing the prism in the sample chamber of the instrument. The identification of an unknown crystal structure can be made by comparing the reflected light of the crystal to the reflected light of known crystal structures. By this means the crystal structure of unknown sample lead chromate was determined by comparing to knoKn standards of the two crystalline forms. The color of certain materials may be an indication of their purit,y-for example, @-naphthol when pure is white but when impure is tan. The purity can be determined by measuring the reflected light by passing light through the crystals and a rightangle prism into the instrument. The reflected light can be compared to the reflected light of known purities. Microbiological Assay Methods. LOUISSIEGEL,Food Research Laboratories, Long Island City, x. Y. hlicrobiological assay compares favorably with chemical assay of many vitamins and drugs, and in many cases makes an assay possible where chemical methods fail. Conditions for a precise and reliable microbiological assay were discussed in detail, including the organisms used and the criteria used to evaluate the assay.
Symposium on Spectroscopic Equipment The Society for Applied Spectroscopy, in cooperation with the Polytechnic Institute of Brooklyn, Brooklyn, S. Y., is completing plans for a symposium on spectroscopic equipment on May 22, under the chairmanship of W. L. Parker. The latest developments in instruments in the fields of absorption and emission spectroscopy will be exhibited.
International Congress on Analytical Chemistry The International Congress on Analytical Chemistry, meeting June 1 to 3 a t Utrecht, Holland, has completed its program, and a limited number of copies may be obtained from the office of ANALYTICAL CHEMISTRY, Washington, D. C. Members will receive preprints of papers in advance of the meeting. All correspondence should be addressed to the general secretary, H. A . J. Pieters, 7 Beatrixlaan, Geleen, Holland.
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Symposium on Modern Instrumental Methods of Analysis. Minnesota Section, A.C.S., and Institute of Technology, University of Minnesota, Minneapolis, March 22 to 24. American Society for X-Ray and Electron Diffraction, joint with Crystallographic Society of America, Yale University, New Haven, Conn., April 1 to 3. Symposium on Spectroscopic Equipment. Polytechnic Institute of Brooklyn, Brooklyn, N. Y., May 22. Symposium on Analytical Methods in Nuclear Chemistry. Division of Analytical and Micro Chemistry, Northwestern University, Evanston, Ill., Aug. 13 and 14.
