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IN a previous communication1we have described procedures for the separation, by paper chromatography, of the natural ester alkaloids derived from veracevine, cevagenine and cevine, as well as some partially synthetic esters of these alkamines. The most suitable solvent system proved to be chloroform on formamide-impregnated paper; detection was carried out with Dragendorff's reagent or by reaction with concentrated sulphuric acid.

MANNOSIDOSTREPTOMYCIN in some streptomycin preparations is conveniently detected by the paper chromatographic procedure of Winston and Eigen1. In the presence of high concentrations of salts such as in ion-exchange column eluates, or in fermentation broths, this procedure is not applicable: attempts to desalt such solutions, by mixed-bed ion-exchange, electrolytic de-ionization or solvent extraction, have proved unsuccessful. We have found it possible to separate streptomycin, mannosidostreptomycin and allied substances by paper electrophoresis, having developed (independently) a technique similar to that used for new antibiotic broths by Hosoya et al.2, and King and Doery3.

INTERPRETATION of the results of paper electrophoresis1–3is complicated by liquid movement in the paper, due to hydrostatic flow, attainment of equilibrium in the paper, and electro-osmosis. Hydrostatic flow, due to the difference in level of buffer in the electrode vessels, can be eliminated by arranging a siphon between the vessels1.

AN automatic scanning technique employing a Geiger–Müller tube for the location and estimation of radioactive substances separated on unidimensional paper chromatograms has been described1. The application of this technique to two-dimensional chromatograms is tedious because a large sheet of paper has first to be cut up into the equivalent number of unidimensional strips and each strip scanned separately. To obviate this difficulty, an alternative technique to the conventional form of two-dimensional paper chromatography has been successfully developed for the application of two or more solvent systems to the same labelled mixture.

As you have opened your columns to Mr. Garnett's valuable paper on “Subject-Indexes to Transactions of Learned Societies,” you will perhaps allow me to make a suggestion in regard to the proposal contained in it. The initial objection to Mr. Garnett's scheme appears to me to be that the work he suggests will really be as large as the original catalogue, and, in fact, the same work in a new order. Even were it possible to get the money (probably little short of 10,000l.), the question would naturally arise whether or no the result was likely to be worth this great outlay. Moreover, the plan proposed by Mr. Garnett would not meet the great difficulty of compilation, which consists in the getting together of papers treating of identical subjects, but written with various titles by different persons. This would make it necessary to employ experts in each subject, and also a general practical editor for the whole, under whose eye all entries must pass. I cannot help thinking, therefore, with Mr. J. B. Bailey (p. 580), that the titles of the papers would have to be generally ignored.

BY so-called ‘one-dimension partition chromatography’ on a paper support (first used successfully by Consden, Gordon and Martin1for the separation of amino-acids, and recently adapted by Partridge2for the separation of reducing sugars), we have succeeded in separating the individual members of a mixture of carboxylic acids of the types commonly occurring in plant tissues.

IN view of the recent communication from Flood, Hirst and Jones1on this subject, a description of a method developed in this laboratory may be of interest. The same principle is used for the separation of sugars in a mixture, but a different method of extracting the separated sugars from the paper is employed, and the final estimation is carried out by a micro method free from the disadvantages associated with the Somogyi method and gives directly the weight of the sugar without the use of a reference compound. Certain of the established microchemical techniques developed in the Carlsberg Laboratory2are employed, and the scale of the method is correspondingly reduced. The procedure is, briefly, as follows.

THE Ramage method1for the spectrochemical analysis of solutions has been developed by other workers2. In this method, filter paper is impregnated with the solution and is introduced into the flame or arc in the form of a roll or strip. Mechanical devices have been designed to ensure the steady combustion of the sample2.

Scientific Papers, mainly on Electrodynamics and Natural Radiation: including the Substance of an Adams Prize Essay in the University of Cambridge.

MR. EMIL HATSCHEK has rendered a real service to all students of colloid chemistry by collecting early fundamental papers on the subject, six by foreign investigators being translated into English. The book makes no pretence to develop a historical account of the growth of colloid chemistry, but rather indicates certain outstanding conclusions which subsequent research has substantiated.

Papers of the Society of Mural Decorators and Painters in Tempera.

THE monosaccharide composition of isolated cell walls of strain 7–11–05 of Chlorella pyrenoidosa Chick, an organism proposed for life-support systems in space travel, was examined. The two principal methods used were thin-layer chromatography and paper chromatography, accompanied by appropriate staining.

SEVERAL paper-chromatographic procedures for the separation of the lower fatty acids as their ammonium or ethylamine salts have been described1. They suffer, however, from two disadvantages: formic acid cannot be separated from acetic acid and the time required is about 20 hr. By running the chromatograms at 50–60° C. the time required for the separation of the acids C2to C6could be reduced to 1–2 hr., according to a recent report2.

Dewar and Gunew1have described the use of a serrated glass strip as a collector for column chromatography. In this laboratory a method has been developed in which a moving strip of paper is used for the same purpose.

FOR some time we have used in our laboratories a simple and economical technique for staining protein fractions of human serum separated by electrophoresis on filter paper.

WE have before us a number of reprints of recent papers descriptive of various meteorites. Several of these are by the late Dr. Henry A. Ward and the late Prof. E. Cohen, two of the most indefatigable workers in this subject, whose loss is much to be deplored. In 1904, two years before his death, Dr. Ward published a “Catalogue of the Ward-Coonley Collection of Meteorites,” which is not only a catalogue, but contains, in addition, much useful information, including alphabetical and topographical lists of all known meteorites (about 680 in number). The Ward-Coolney collection, now exhibited in the American Museum of Natural History at New York, is one of the most complete that has ever been made, containing as it does representatives of 603 meteoritic falls; it is further remarkable in that it was brought together in the comparatively short space of time of ten years. Prof. Cohen died in 1905, and a third part of his “Meteoreisenkunde” was published after his death; this, which is the only general work that has yet been attempted on meteorites, unfortunately remains incomplete.

THE Cambridge University Press has during some years past contributed very largely to the progress of physical science by the issue of the collected works of great mathematicians and physicists. The volumes which contain the collected writings of Maxwell, Adams and Cayley form a rich storehouse of knowledge; and the efforts the Press has made to induce living writers, such as Kelvin, Stokes and Rayleigh, to edit their own papers for issue in a collected form deserve the gratitude of all students.

CHLOROPLAST suspensions from Spinacea oleracea or Pisum sativum assimilate CO2in the light at rates comparable with those observed with intact leaves1–3. With most preparations the major photosynthetic products are phosphoglyceric acid (PGA) and dihydroxyacetone phosphate (DHAP)2,4,5. Although the synthesis of these compounds is consistent with the operation of the photosynthetic carbon reduction (PCR) cycle6in the isolated plastids it is still not clear why these particular intermediates accumulate. It has been shown5that the outer membranes of the chloroplasts are permeable to both PGA and DHAP. Thus a large proportion of the carbon fixed into these compounds may diffuse into the external medium. The amount of carbon lost from the chloroplasts will presumably depend on the ratio of the volume of external medium to that of the aqueous phase of the chloroplasts. For chloroplast suspensions containing 100 µg chlorophyll per ml. this ratio would be over 100 : 1, contrasting markedly with the fluid environment of the chloroplasts in vivo, where the ratio of the volume of non-chloroplastic cytoplasm to that of the chloroplasts is usually less than one. It seemed possible, therefore, that more of the PGA and DHAP formed might be metabolized further if the volume of medium in the experimental sample was reduced to a minimum by layering the chloroplasts on filter paper.

IN a communication under the above title, Giri1describes the use of a starch agar gel for the location of amylases on the paper chromatogram. The technique seems to be essentially the same as that used in this Department, and previously described in Nature2.

BY one-dimensional paper partition chromatography, some of the phenolic substances allied to the pyrogallol tannins have been separated. When using the well-known solvent phases such as butanol/acetic acid and phenol, previous workers1have found that the simpler phenols tend to give long diffuse trails. The preparation of the more complex phenols, such as are found among the pyrogallol tannins, is complicated by their ready oxidation in the presence of bases. Tailing of the spots in neutral and acidic solvents is influenced by the acidity of the mobile phase (cf. organic acids2). Addition of strong organic acid to the eluting solvent causes separation into well-defined spots. Unfortunately, formic acid greatly increases the rate of run of the tannin, the spots coming too close to the solvent front for clear definition. Two new solvents have now been found which separate many mixtures of complex phenols into well-defined spots : (1) phenol/acetic acid/water, prepared by adding 30 ml. glacial acetic acid to approximately 500 ml. liquid phenol and just saturating with water at room temperature ; (2) phenol-trichloracetic acid/water, prepared by adding 35 gm. trichloracetic acid to approximately 500 ml. liquid phenol and just saturating with water at room temperature.

THE identification of sulphonamides in biological fluids is usually attempted by microscopical examination of crystals and by the use of various, rather non-specific, colour reactions1. Since it is common for only small quantities of fluid to be available, it was decided to investigate the possibilities of paper partition chromatography.

THE technique of paper chromatography devised by Consden et al.1for the qualitative analysis of ammo-acids has since found wider spheres of application2. Bate-Smith3described its application to anthocyanins, flavones and other polyphenolic substances.

PROTEINS of the lens tissue of the eye have been extensively examined because of their relationship with cataract formation. In all forms of cataract a decrease was found in the total amount of lens proteins as compared with normal lens of the same age1. Changes in the proportion of the soluble proteins of the lens measured by electrophoresis have been reported in different kinds of cataract; but, according to van Heyningen2, no consistent patterns have emerged from these investigations. The work recorded here was carried out to determine the behaviour on paper electrophoresis of soluble lens proteins of the rat, as well as the possible changes in the proportion of the different fractions during lactose feeding.

IN paper chromatography, the RFvalue, or ratio of distance travelled by substance to the distance travelled by solvent front, is generally used as the criterion of identity. If two substances have the same RFvalues in two or more solvent systems, they are assumed to be identical. But although RFvalues are often quoted with great precision, experience shows that they are, at best, only a rough guide and should not be used as the sole means of identifying a substance.

IN the course of a paper chromatographie study to detect possible crop residues of an organophosphorus insecticide it became apparent that benzene extracts of untreated check samples of a red variety of Irish potatoes. sugar beets, Valencia oranges and Staymen apples produced cholinesterase-inhibiting spots.

A NUMBER of sulphoxides have been found to occur naturally in plants1(for example, alliin, s-methyl-L-cysteine sulphoxide, glucoiberin). To aid in the detection of sulphoxides on paper chromatograms, a specific sensitive test has been devised. The test, which is based on the reaction of sulphoxides with hydriodic acid to form iodine2, is presented here.

THE usefulness of [(carboxymethylimino)bis(ethyl-enenitrilo)]tetraacetic acid (DTPA) in correcting iron chlorosis induced by lime in plants has been well documented1,2. DTPA labelled with carbon-14 was required to facilitate studies concerning the metabolism of the compound in plants ; accordingly, the synthesis was undertaken. The method used involved an alkylation of diethylenetriamine (DET) with bromoacetic acid. In preliminary work, it became evident that the usual methods available for determining chelating materials, such as titration with calcium ion in the presence of oxalate or sprays with a nickel-dimethylglyoxime reagent, would not be satisfactory for following the course of the reaction. These reagents will neither indicate the distribution nor detect all the compounds arising as a result of incomplete alkylation. Paper electrophoresis was found to be a very powerful tool for the delineation of all the compounds formed in the reaction.

THE quantitative determination of paper chromatographic spots is usually carried out by using a variety of photometric techniques. In many instances, however, the known methods lack specificity, reliability and sensitivity.

THE composition of protein mixtures extracted from different sources can be found by the usual methods of paper electrophoresis, but the localization of protein fractions in tissues can only be determined with preliminary preparative breakdown of tissues and organs.

AN improved method, of paper ehromatography has been used, to aid the separation of galactosamine hydrochloride from other hexosamine hydrochlorides in acid hydrolysates of chondroitin sulphate and to investigate the isomerization of N-acetylgalactosamine in alkaline conditions.

WE have found that, when a mixture containing barbiturate, salicylate and acetophenetidin is subjected to chromatography on Whatman No. DE20 cellulosic ion-exchange paper in dilute ammonia solution, a partial resolution of the components is possible. Salicylate is clearly separated from the other two compounds, which move together with only partial resolution (Fig. 1).

THE capacity of an enzyme preparation to activate amino-acids is usually measured by means of the amino-acid dependent isotope exchange reaction between pyrophosphate labelled with phosphorus-32 and adenosine triphosphate1. According to the procedure usually adopted, the labelled adenosine triphosphate is separated from the other components of the incubation mixture by treatment with charcoal. The pyrophosphate of the adsorbed adenosine triphosphate is eluted by hydrolysis with hot hydrochloric acid. The radioactivity is determined and calculated per μmole adenosine triphosphate. For measurement of whole series of individual amino-acid activating enzyme activities in tissue preparations there was a need of a simple procedure which also could be used on a semi-micro scale. A scanning method was therefore developed involving paper chromatography combined with radioautography of the papergrams.

SUCCESSFUL separations of amines by paper electrophoresis were first described by R. Weber1who applied a potential gradient of 10 V./cm. at pH 3.8. Several authors2have since reported on the usefulness of the technique for resolving mixtures of simple, biogenic and poly-amines. All, except J. Gayer3, have used low to moderate potential gradients and varying electrolyte solutions.

ONE of the advantages of the ion-exchange cellulose papers as chromatographic media is their ability to exhibit both ion-exchange and cellulosic properties. Thus, it has been shown that ion-exchange separations can be combined with those of a partition type as a two-dimensional chromatogram to form a rapid and efficient means of resolving mixtures of inorganic ions1.

AROMATIC nitro compounds have previously been detected on paper chromatograms by reduction, diazotisation and coupling with a phenol1as this method has not been found satisfactory for 2:4-dinitrophenyl derivatives, for example, 2:4-dinitro-phenyl-amino-acids, two other methods which can be used in the presence of free amino-acids have been devised in addition to that of Grassmann and Riedel2.

DURING experiments aimed at improving present staining techniques of paper electrophoretic patterns, it was observed that paraffin-oil is strongly adsorbed to heat-denatured proteins giving rise to water-repellent protein-dye complexes. This permitted a method to be devised by which the total area occupied by each fraction of a protein mixture, such as serum, is visualized as a sharply delimited zone against a fully white background1.

ESCULETIN was found in an extract of plant tissue which contained caffeic acid. The esculetin was not a natural product but was formed from caffeic acid during the paper-chromatographic purification procedures. This conversion was confirmed by two-dimensional chromatography of authentic caffeic acid.

SEVERAL papers1,2have been published on the separation of strychnine and brucine by paper chromatography, but none of these gives a satisfactory separation of these alkaloids, particularly in regard to the quantitative determination of strychnine after its elution from the chromatogram. The difference between the RFvalues of strychnine and brucine is only 0.15–0.18 even under the optimum conditions.

RECENTLY, it has been obvious that in most biological materials N-acetylsialic acid (N-acetyl-neuraminic acid) and N-glycolloylsialic acid occur together. By the introduction of a micromethod for the determination of glycollic acid, Klenk and Uhlenbruck1have made possible the evaluation of the amount of N-glycolloylsialic acid in isolated sialic acids. In search of a more direct method, we tried partition chromatography, employing the solvent systems previously used for the separation of sialic acids but with unfavourable results2,3. As the pKaof sialic acids are low, about pH 2.7, it is necessary to use rather a strong acid in the solvents to prevent the dissociation of the carboxylic group. Of the different acids tried, only trichloracetic acid and hydrochloric acid were suitable. On crystallization of the sialic acids we had observed that N-glycolloylsialic acid was much more insoluble in alcohols than N-acetylsialic acid. Therefore, we tried mixtures of alcohols with the acids mentioned above. The best results were obtained with n-butanol/n-propanol/ 0.1 N hydrochloric acid (1:2:1, v/v). In this solvent the RFvalues were for N-acetylsialic acid 0.45, and for N-glycolloylsialic acid 0.34, on Whatman paper No. 1. The solvent system applied cannot be used for the separation of diacetylsialic acids and is unsuitable for the separation of free acids and the methyl esters of the sialic acids.

CONTINUING the study of trace substances in photographic gelatin1,2, paper electrophoresis is being used for investigating the reducing agent present. Tha main interest is in the substance(s) which react immediately with iodine.

THE analysis of the protein composition of blood serum or plasma by means of zone electrophoresis on filter paper has stimulated interest in clinical laboratories throughout the world. In addition to numerous publications dealing with the applications of the technique in various pathological conditions, critical assessments of its validity and accuracy have appeared1–4, in which attention is properly directed to the limitations of the method from the point of view of the numerical evaluation of the separated protein fractions. It has seemed desirable to undertake a study of the accuracy and reproducibility of this method of protein analysis, using two of the most commonly employed protein-dyeing techniques.

Buzzati-Traverso and Rechnitzer proposed a simple chromatographic technique for taxonomic studies on fishes1; Buzzati-Traverso applied it also to genetic studies on Drosophila2. In the original technique, the tissues were simply squeezed on filter paper, dried and chromatographed. The method was used almost as such by some authors for taxonomic studies on land snails3, mosquitoes4, and for investigating several mouse and tumour tissues5. The present method, although starting from the same principle, was developed in a rather different manner. It does not utilize fresh tissues, but tissues which have been dried and powdered. By this means it is possible to use an accurately known amount of tissue, independently of its water content, and to extract completely the free metabolites from the broken cells; furthermore, the samples used may be larger, thus allowing the detection of metabolites which may be present in amounts too small to be detected by the use of small pieces of tissue.

RECENT advances in chemotherapy present the police toxicologist with the problem of extracting and identifying from viscera an increasing number of basic organic compounds. In the past, methods of identifying less than milligram quantities of basic poisons extracted from the body have depended on colour reactions and micro-crystallography. Little is known of the fate of these new drugs in the body, and their reactions with the alkaloidal reagents are often unpublished. Paper chromatography is obviously the method of choice for the preliminary sorting on a microgram scale of these poisons from one another and from their metabolites.

EARLIER investigations in this Institute1have shown that substances like dyestuffs and some proteins show a very marked increase of adsorption on to filter paper and other adsorbents in presence of salts in large concentrations. The adsorption may thus be increased from practically zero (in pure water) to considerable amounts, and the phenomenon may be utilized for chromatographic separations, using salt solutions of lower concentrations or even water for the elution. Similarly, Holman and Hagdahl2found that the adsorption of fatty acids on to carbon from solutions in ethanol was very markedly increased if the solubility was reduced by adding water to the solution.

SEVERAL recent publications have attested to the utility of the technique of paper partition chromatography in the separation and identification of phenolic substances. Bate-Smith1described its application to anthocyanins, flavones and other polyphenolic substances using a butanol – acetic acid – water system and ammoniacal silver nitrate as a detecting reagent. Evans, Parr and Evans2used butanol – pyridine – aqueous sodium chloride and diazotized sulphanilic acid (Pauly reagent) to separate and detect simple phenols and their derived phenolic acids. Gosta Lindstedt3, applying the technique to the separation and identification of nine phenolic constituents of pine heartwood extracts, found that best results were obtained with a water-saturated mixture of benzene and ligroin containing traces of methanol. Bis-diazotized benzidine was used as the detecting reagent. A phosphomolybdic acid detecting reagent was used by Riley4in applying the technique to common phenols in benzene – alcohol – water systems. In studying lignin degradation products, Hossfeld5first coupled the phenol mixtures with diazotized sulphanilic acid and then separated the sodium salts of the dyes formed using a methyl ketone – water system.

THE following technique for the separation of phenols, phenolic acids and their derivatives by one-dimensional paper partition chromatography has been developed as part of a two-dimensional method (to be published shortly) for the investigation of serum and urinary phenols in patients suffering from acute uræmia.

THE separation of mixtures of amino-acids into discrete spots on paper chromatograms has hitherto almost invariably been carried out using solvents only partially miscible with water. However, in work concerned with the separation of certain peptides we found that the usual solvents (namely, butanol, benzyl alcohol, phenol, collidine) were inadequate, and in consequence sought alternative solvents.

THE methods so far described in the literature for the identification of spots of purines, pyrimidines and their derivatives on paper chromatograms are unsatisfactory. We have found a simple and rapid method for their detection.

THE separation of amino-acids by partition chromatography on paper was first described by Consden, Gordon and Martin1. A large number of separations of organic compounds has been described since then. I have recently discovered that cations can be separated successfully if the solvent is adjusted suitably to prevent hydrolysis. The solvent selected for study Was butanol saturated with N aqueous hydrochloric acid.

THE application of paper chromatography to the separation1, identification, and quantitative micro-determination2of the sugars, in investigations of the carbohydrate group, is an advance of no small importance. However, the use of ammoniacal silver nitrate, which gives a similarly coloured dark spot with all the reducing sugars, as colour reagent, often leads to uncertainty, especially when the RF values of the sugars are close.