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the peak for phosphate middle groups and one of the peaks for phosphite (ortho- or pyro-) exhibit the same chemical shift of 120 p.p.m., it is possible t o determine both of these species in a mixture by using the second phosphite peak at 64 p.p.m. to determine the relative amount of phosphite and subtracting this value from the relative amount of the middle group plus phosphite as determined from the 120 peak. The other case where interference is possible is between the hypophosphate and hypophosphite, but here again another peak for the hypophosphite at either 42 or 133 p.p.m. can be used. The relative concentrations of the different phosphorus-containing anions listed in Table I are determined by measuring the area under the respective peaks. So far we have measured relative amounts in various mixtures with an accuracy within 2 to 10%. These relative values can be converted to absolute quantitier! by adding a known amount of one of the phosphoruscontaining anions to the solution being analyzed. However, the easiest procedure is t o determine total phosphorus by one of the standard procedures (such as a molybdate titration following conversion of all of the phosphorus to the orthophosphate form). At the present stage of the art, analyses by nuclear magnetic resonance are applicable only to relatively concentrated solutions containing at least a few moles of phosphorus per liter. Thic: restricts this method of analysis to the acids, alkali metal, and ammonium salts in most cases. However, cations causing precipitates can be removed prior to analysis by ion exchange resins ( 2 ) ; and concentration by evaporation has proved feasible. In some cases, it is convenient to make the spectral measurementi on supersaturated solutions. The spectrometer used in these studies was a high-resolution instrument manufactured by Varian Associates (9), equipped with a 12.3-mc. probe. By using a 17.2-mc. probe and a 10,000Gauss field, the resolution and signal-to-noise ratio should improve substantially, and give much higher accuracy and less difficulty with interferences. Comecutive analyses can be car-
ANALYTICAL CHEMISTRY ried out at the rate of approximately 12 samples per hour. The resonance measurement itself takes less than a minute. .4 detailed paper on this subject will be published as soon as certain effects now under study are precisely evaluated. These effects include a slight, theoretically predicted, shift‘ of the resonance peak with pH, and the interference between phosphate middles and pyrophosphite, as well as the interference betveen hypophosphate and hypophosphite. Substitution of nitrogen for oxygen in the inorganic acids seems to cause very little shift in the resonance peak. Thus, mono- and diamido-orthophosphates resonate very close to the regular orthophosphate ion. LITERATURE CITED
(1) Gutowsky, H. S.,JIcCall, D . W., and Slichter, C. P., J . Chem. Phus. 21, 279 (1953). (2) Helrich, K., and Rieman, W., ASAL. CHEM.19, 651 (1947). (3) Shoolery, J. S . ,Ibid.,26, 1400 (1954). (4) Van Waser, J. R., “Encyclopedia of Chemical Technology,” Kirk and Othmer, editors, vol. X, pp. 403-29, 469-72, 482, 488-92, Interscience, New York, 1953. (5) Van Waser, J. R., J . A m . Chem. Soc. 72, 644, 647 (1950). (6) Van Waser, J. R., Callis, C. F., and Shoolery, J. N., Ibid., 77, 4945-5 (1955). (7) T-an Waser, J. R., Griffith, E. J., and McCullough, J. F.. ANAL. CHEM.26, 1755 (1954). (8) Van Wazer, J. R . , and Holst, K. A,, J . Am. Chem. SOC.72, 639 (1950). (9) Tarian .4ssociates, Palo Alto, Calif., Radiofreguency Spectroscopy 1, KO.1 (1953), No. 2 (1954), S o . 3 (1955). RECEIVED for reriew August 19, 1955. Accepted November 7, 1955
Inorganic Division Research Laboratory Monsanto Chemical Co. Dayton, Ohio Varian Associates Palo Alto, Calif.
C . F. CALLIS J. R. V.4N WAZER
J. K, SHOOLERY
MEETING R E P O R T
Society for Analytical Chemistry meeting of the Scottish Section with the StirlingATshirejoint Sections of the Royal Institute of Chemistry and the Society of Chemical Industry, held at Grangemouth on November 2, the following lecture was given. Some Industrial Applications of Ion Exchange Materials. T. R. E. KRESSMAN, Permutit Co., Ltd., London. Ion exchange resins are now widely used in industry. The major use is still in t h e field of water treatment, but the high capacity and stability of the modern resins based on polystyrene have enabled them to be used in many fields other than water treatment-in metal finishing, in glycerol and gelatin manufacture, and in the manufact u r e of antibiotics. The conventional method of demineralizing water and solutions of nonelectrolytes is with a column of cation and a column of anion exchanged material in series. More recently, the mixed-bed technique has been applied, in which the liquid is flowed through a single column of a n intimate mixture of the two exchangers. Brackish waters, and solutions of high electrolyte content, cannot be economically treated by the column method. A very recent process whereby they can be desalted economically makes use of an electric current in a multiconipartment electrodialysis cell in which cation and anion exchange membranes are arranged alternately between a pair of electrodes. Much development work still needs t o be done on this, however, before it becomes a commercial possibility.
.It a meeting of the Midlands Section held in Kottingham October 25 a lecture demonstration on ring-oven technique was given by H. Weisz, Technical University, Vienna, winner of the Feigel Prize, 1955. The ring-oven technique is a simple method for separating ions, or groups of ions, in one single drop. An apparatus called the ring oven is designed to mash soluble materials out from a spot on a filter paper and to concentrate them in a sharply bounded circular ring zone, where they can be detected. Some other pieces of equipment have been developed for this purpose. With the aid of this method a n analytical scheme for 14 commoner ions has been worked out; one drop of about 1.5 pl. is sufficient for the analysis. The method has also been employed for ring colorimetric analysis.
The Physical Methods Group met jointly with the Western Section at Bristol University on October 28. The following papers Fere presented and discussed. X-Ray Analysis of the Structure of Vitamin BIZ. DOROTHY CROWHODGKIN.
FOOT
Since the isolation of crystalline vitamin BIZ7 years ago, we have used x-ray diffraction methods to assist in finding the chemical structure of the vitamin. Our examination has been closely interlocked with chemical investigation8 carried out in a number of laboratories. These showed that the vitamin had approximately the formula CSI-UHBI--O?NMOIBIJPCO,and contained a CN group, a nucleotidelike group built of bensiminasole, ribose, and phosphate units, a
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V O L U M E 28, N O . 2, F E B R U A R Y 1 9 5 6 propanolamine residue, and probably six amide groups attached to a large remaining nucleus of unknown structure containing about 45 carbon atoms. K e have found i t possible to discover t h e arrangement of t h e atonis in this nucleus through t h e calculation of the electron density distribution for four different crystals, air-dried and wet B E crystals, R12.SeCN, and a hexacarboxylic acid degradation product of Biz prepared by Cannon, Johnson, and Todd. I n these calculations we have used phases for t h e terms in t h e Fourier series employed based on, first, t h e cobalt atoms, and then on gradually increasing known regions of the structure: the correct atomic positions can be selected from among t h e many spurious peaks t h a t appear in the first approximate calculated distributions. The whole project has required very heavy computing which has been carried out partly in this country. partly in America. We can now write a tentative complete structure for the vitamin. The inner nucleus is found to have interesting and unexpected structural relations with porphyrins. T h e molecule as a whole is very compact: a number of small chemical modifications can be made in its structure, which leave unchanged its abi1it)y to form crystals with essentially similar molecular arrangement. X-Ray Fluorescent Quantitative Analysis a s a Tool in Archeology. E. T. HALL. During the past few years in America the use of x-rays for chemical analysis has been investigated, and in one instance a coinmercial apparatus developed for use in industrial applications. I n thia country, however, very little work has been done in this direction. This paper described a n apparatus which has been developed for use in archeology and kindred subjects. A knowledge of the composition of artifacts can help t o elucidate problem3 concerning not only their genuine attribution, but also trade routes and inethods of manufacture in t h e ancient world. T h e possibility of using this method for routine laboratory and industrial applications was discussed, giving some idea of t h e advantages and limitations of x-ray analysis. X-Ray Diffraction Techniques in the Investigation of Crime.
E. B. PARKES. T h e employment of x-ray diffraction analyses-a further step towards actual identification in criminological jnvestigations.
organized b y t h e Biological AIethods G r o u p wau held K o v e m b e r 22 in London to discuss "The E v a l u a t i o n of iintifungals."
A
JIEETING
eliminate them from treatment comparisons. T h e results of fungicide tests are now never exactly reproducible, in t h a t a standard substance will induce a slightly different response under identical conditions on different occasions. Inherent variability differs from fungus t o fungus, and may influence t h e choice of test organism. Comparisons of two fungi in the same test are usually difficult. Cattle Ringworm.
Problems in the Evaluation of Treatment.
K. C. SELLERS,Animal Health Trust Livestock Research Station, Stock. Essex. Recent work (iiinsworth, G. C., and Austwick, P. K. C., V e t . Rec. 1955, 67, 99; Sellers, K. C.. La Touch, C. J., and Sinclair, W. B. I:., iii preparation) has shown t h a t Trichophvton z'errucosum Bodin, var.
discoides Georg, is the prevalent cause of cattle ringworm in this country. I n Yorkshire t h e infection was found on a high proportion of farms, more commonly in calves in their first year of life and during the winter. Humans contract the infection, but no accurate estimate of t h e incidence in this species has been made. As a preliminary to n.ork on control and treatment of cattle ringn-orm in the field, experimental observations have been carried out with the following results. Healthy calves were infected artificially by rubbing natural material or culture suspensions into the unabraded skin. Lesions were detectable within 30 days and spontaneous recovery occurred in about 4 months, when no indication of infection could be detected. Recovered calves resisted reinfection. Histological studies showed that in the early stages of infection there was a prolific distribution of fungal mycelium in the extra- and intrafollicular stratum corneum. Later t h e follicular space around t h e hair was invaded and a loose niycelial network developed round the hair shaft. T h e mycelium then penetrated all parts of intrafollicular portion of the hair except the living bulb and a spore sheath formed both on the surface and in the medulla of the hair shaft. KO tissues other than those in which keratin could be demonstrated histologically were invaded. T h e tissue response of the host resulted in the eventual separation of the stratum corneum from the underlying tissues. These surveys and experimental studies have shown t h a t although satisfactory in vivo trials might be performed in t h e artificially infected calf, the final and accurate assessment of an antifungal under field conditions presents many problems. Nevertheless, cattle ringworm lends itself t o well planned clinical trials; not only is it widespread, but ethical and cosmetic considerations do not bulk so largely as in man. Also, it is possible t h a t t h e results so gained would be applicable to the ringworms of other species.
of t h e XIidlands Section on November 9 in Birmingham a discussion o n spectrophotometric titrations was opened b y R. A. Chalmers, D u r h a m University, a n d S. J. Clark, British S y l o n Spinners, Pontypool, ?\Ion. A MEETISG
Laboratory Evaluation of Drugs for Clinical Trial against Dermatomycoses. H . 0. J. COLLIERA N D G. K. A. SMITH,Allen & Hanburys, Ltd., Ware, Herts. Dermatophytes-fungi causing superficial infection of skin or its appendages-present an important clinical problem in nian and domestic animals. T h e laboratory evaluation of potential remedies is a t present handicapped by t h e scarcity of suitable experimental dermatomycoses. I n t h e absence of in vivo therapeutic tests, evaluation requires a variety of methods, particularly for studying skin toxicity, keratin penetration, and in vitro antifungal activity. In toxicological studies methods include intradermal injection and repeated application to t h e unbroken skin; for the latter te3t hairless mice are found suitable. Evaluation of in vitro antifungal actiyity includes tests of fungistatic and fungicidal action and of possible antagonism by materials such as hair and serum, with which the potential remedy is likely t o come in contact. Aspects of the above methods were illustrated from experience, using new bis-quaternary antifungals. Some Factors in t h e Planning of Fungitoxicity Experiments in the UiiiverAtj- of Laboratory. R . J. W. BYRDEAND G . .?I. CL.ARKE, Bristol, Research Station, Long Ashton. Controlled hydrogen ion concentration is important in all laboratory fungitoxicity experiments, particularly when testing weak acids or bases. I n general, such compounds are most toxic in t h e undissociated form, owing t o greater ease of penetration of t h e lipophilic cell membrane. For valid comparison of inherent toxicity, they should be tested a t a p H level where they are predominantly undi.5sociated. T h e buffer chosen should not react with the test fungicides, while t h e culture medium should be t h e simplest which permits normal grox-th of t h e fungus. T h e performance of a fungicide may be profoundly modified by its physical form, or by the presence of a mutual solvent. Possible modifications in technique when testing volatile fungicides are discussed. Laboratory experiments are carried out in incubators which themselves introduce sources of variation in t h e fungal material used. These variations must be examined and experiments so designed as to
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Mr. Chalmers. It is possible t o classify spectrophotometric titrations according t o t h e component of which the extinction is measured, and t o predict from theory the conditions necessary for a satisfactory end point to be obtained. Spectrophotometric titrations seem t o be particularly suitable for development as automatic or semiautomatic methods. Mr. Clark. Some advantages of spectrophotometric detection of the end point of a titration were considered and practical examples were described. Milligram amounts of weak organic acids and bases may be titrated accurately and precisely by this technique. The method is in routine use for the determination of neutralisation equivalents of such compounds. The ultramicrodetermination of nitrogen may be achieved by Kjeldahl digestion followed by oxidimetric determination of the ammonia formed. Spectrophotometric titration allows the use of solutions as dilute a s lO-'.Tf. Turbidimetric and nephelometric titrations were considered: the nephelometric titration of potassium was described. T h e conversion of a rommercial spectrophotometer was described, together with some of t.he difficulties which arise when this instrument is used for turbidimetric titration.
.it a special meeting held S o v e m b e r 29 i n London, a lecture on t h e development of polarographic analysis was given b y J. lIeyrovsk$, C e n t r a l I n s t i t u t e of Polarography, Prague. T h e subject was treated under the follon-ing main headings: types of mercury capillary electrodes; direct and indirect polarographic determination; conversion of inactive substances into depolarizers; Subtractive and derivative polarography: continuous recording of the mean current or the current-voltage curves with special electrodes; the use of nonaqueous solutions; polarometric titrations: chromatoIiolarography : cathode-ray polarographs; the electronic polaroscope based on potential-time curves produced with alternating current.
