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Chromatographic resolution of protein mixtures: egg albumin and lysozyme, and another containing insulin and protamine (Mugil cephalus) was achieved on paper strips using a several step elution with neutral salt solutions of increasing concentrations. Experimental data concerning the influence of cations and anions on chromatographic separation of proteins on paper strips are presented.

The presence of cysteine and glutathione in concentrates of the sulfhydryl constituents of orange, grapefruit, lemon, and lime has been established by filter paper chromatography. The cysteine and glutathione content of concentrates prepared from fresh and/or heated orange, grapefruit, lemon, and lime juices has been determined by direct photometric analysis on filter paper chromatograms. Heating the fresh juices resulted in significant losses of both cysteine and glutathione.

Following previous supplements in this series, a further 180 compounds were analyzed by paper chromatography in six solvent systems. The data originating from 15 standard colour reagents are also recorded and presented. The following types of compounds are described: flavonoid derivatives, aliphatic and aromatic aldoximes and ketoximes, substituted benzamide derivatives, aminobenzene derivatives and heterocyclic amines, N-nitroso compounds, N-oxides of tertiary bases, pyrimidine and indole derivatives and sulphonamide drugs. The paper chromatographic mobility patterns were characteristic, especially for 1,3- and 1,4-hydroxybenzaldoximes and ketoximes of the hydroxyacetophenone type. All the heterocyclic bases investigated showed mobility patterns similar to those of the alkaloids described in earlier supplements. Mobility patterns similar to the alkaloids were produced by some of the mercaptopyrimidines. In general amino-, diamino-, hydroxy and dihydroxy derivatives of pyrimidines showed low mobility in these solvents. Several flavonoid compounds were found to be Erhlich positive and a magenta colour was produced by l -epicatechin. Most of the N-unsubstituted benzamides were detected with p -dimethylaminocinnamaldehyde, and most of the N-nitroso derivatives of secondary amines and N-oxides of heterocyclic tertiary amines were revealed by this reagent.

A paper chromatographic solvent system and an extraction and concentration microtechique were used to determine air-borne 1,2:3,4-dibenzopyrene, 3,4-benzofluoranthene, 3,4-benzopyrene, 1,12-benzoperylene and anthanthrene in an automobile tunnel, in frequented cross roads, ad in sites with little or no automobile traffic. Fluoranthene, pyrene, chrysene, 1,2-benzanthracene, 1,2:5,6-dibenzanthracene, 11,12-benzofluoranthene and coronene were identified on the same chromatogram, 1,2-benzopyrene was presumed. Using at least three filters in series, quantitative air-sampling of penta- and higher cyclic hydrocarbons is claimed. The results are tabulated.

The purpose of this paper is to develop an analytic model which can be applied to the disposal of various components of municipal waste. Utilizing data from the City of Philadelphia, this paper examines the generators of used newsprint; the interactions between incineration, landfill, and the beneficial extraction of the caloric content of paper for steam generation: and the feasibility of recycling. The social cost issue is considered in light of present City disposal practices Finally, an attempt is made to derive optimal collection and disposal policies for FY 1976 as functions of various model parameters. The paper concludes that the construction of a steam generation plant is a viable alternative to present disposal practices for a range of processing costs.

Differentiation of radioactive DNA and RNA deposited on filter paper discs can be accomplished by a relatively simple procedure. RNA can be efficiently removed by incubating the dises, impaled on pins, with 0.2 ml of 0.5 n NaOH for 90 min at 37°C. DNA can be removed after NaOH hydrolysis by treating the discs with 5% TCA for 30 min at 90°C. A correction is necessary to determine the actual amounts of DNA and RNA in order to account for the loss of DNA (13.8%) during the NaOH hydrolysis procedure.

A two-dimensional paper chromatographic method is described which allows good separations and spectrophotometric determinations of nanomole amounts of hypoxanthine, xanthine, uric acid and uric acid riboside. The method can be applied to biological material containing adenine nucleotides and considerable amounts of free amino acids.

From their experience of this market and using a combination of trend projection, correlation analysis and market research, Messrs. Clark and Cockram forecast that consumption of printing and writing paper in Western Europe will increase from 8.9 million tonnes in 1972 to 13.3 million tonnes in 1977: an average increase of 8% per annum over a five year period. Recovery from the recent recession will lead to a very rapid increase of consumption in 1973 ( 16% higher than 1972) and in 1974 ( 10% higher than 1973) followed by two years of below average growth. Consumption of coated paper will continue to grow at a faster rate than uncoated, averaging 12% a year. 1973 will be a year of very rapid growth (25%) followed by two years of more moderate growth (13% and 9% respectively) and in 1976 a year of very little growth (2%). By 1977, coated paper will account for 35% of total printing and writing consumption compared with 30% in 1972. The growth in demand for uncoated paper will be less dramatic and also less variable than the growth of coated paper. Between 1972 and 1977 consumption is forecast to increase at an average rate of 7%. Again, 1973 will see the fastest growth ( 12%) while the lowest growth (3%) is expected to be in the years 1975 and 1976. Indeed, there is some danger that a period of stagnation or even another recession could affect paper consumption by 1976.

Summary o 1. Methods for the detection of steroids in paper chromatography have been described and evaluated for 31 compounds. 2. A new method of detection of steroids involving phosphomolybdic acid has been reported. 3. A method using silicotungstic acid has been extended to cover many new compounds.

A highly specific method for qualitative and quantitative analysis of reducing carbohydrates has been described. The method involves the measurement of the amount of tritium found in [ 3 H]sodium borohydridereduced sugars following their paper chromatographic separation on ion-exchange papers. These procedures may be used to quantitate all of those components in 5 μl of a mixture which are present in amounts ranging from 0.1 to 10,000 nmoles. The quantitation gives approximately 10% accuracy at the lower end of the sensitivity range.

The RF values of a series of eleven phenols have been determined using paper-chromatographic techniques on filter paper loaded with ion-exchange resin. The data have been used to predict the separation of various mixtures of these phenols by development with aqueous solutions of acetic acid.

Methodology for obtaining reproducible measurements of the relative mobility of organic compounds over pH 2–12 using high-voltage paper electrophoresis is described. Use of the method for the elucidation of some structural features of simple molecules is illustrated by applying it to the characterization of metabolites of drugs excreted in the urine and bile of rats. The compounds studied included p -nitrophenol, 1-naphthol, salicylic acid, 4-nitrocatechol, probenecid, phenol red, and their metabolites.

This paper presents the results of the application of circular filter paper chromatography to the differentiation of pathogenic and non-pathogenic staphylococci by means of an arginase test, and to the differentiation of haemolytic streptococci and viridans streptococci by an arginine dihydrolase test. Chromatographic assay indicates that in the group of staphylococci only the pathogenic and not the non-pathogenic staphylococci metabolize arginine to ornithine and urea (presence of arginase). Chromatographic assay indicates that in the group of streptococci only the haemolytic streptococci and not the viridans streptococci metabolize arginine to ornithine and citrulline, or to ornithine or citrulline only (presence of arginine dihydroase in the haemolytic group).

A study was conducted to determine a more efficient means of preparing paper resistant to liquid penetration through addition of rosin and papermakers' alum to cellulose. Paper sizing is accomplished by depositing a hydrophobic aluminum-rosin precipitate on the cellulose fibers. In order to optimize the interaction with cellulose, it is necessary that the precipitate be positively charged. It was hoped that proper control of the particle size and the electrokinetic potential of the precipitate prior to addition to the pulp would result in a more efficient sizing of the cellulose fibers. The appropriate conditions were determined under which a highly dispersed stable positively charged colloidal suspension of rosin acid in the presence of aluminum salts could be prepared. Considerable differences were observed with Al 2 (SO 4 ) 3 and Al(NO 3 ) 3 as a result of the presence of the divalent sulfate ion. A series of sized paper handsheets were prepared using preformed positively charged aluminum rosinate suspensions and their resistance to liquid penetration was determined. Inferior results were obtained with the preformed suspensions when compared to the normal means of in situ sizing where rosin size is added to the cellulose suspension followed by alum. Further paper handsheet trials were carried out in an attempt to determine the reasons for decreased sizing efficiency obtained with the preformed precipitate. The results are discussed in terms of the most important mechanisms involved in the sizing of paper.

The migration of 26 ions on anion-exchange paper is studied with five different complexing solvents. The results are reported as a function of the sign of the charge on each ion determined electrochromatographically. Several possible separations are presented, but it is shown that the prediction of separations, knowing only the charge on several substances, is impossible. It is also demonstrated that ion-exchange column experiments and ion-exchange paper experiments do not necessarily yield identical results.

The most satisfactory type of support for routine use in reversed phase paper chromatography of dinitrophenyl (DNP) derivatives of amines has been found to be paraffin-treated paper, which gives good resolution, is relatively easy to prepare and handle, is stable and on which the solvent, a mixture of chloroform, methanol and water, runs reasonably fast. Human urine contains methylamine, dimethylamine, ethylamine, pyrrolidine and piperidine.

Pyrimidine and purine bases analysis by time of flight mass spectrometry and paper chromatography

Total alkaloidal extracts from four closely related Lobelia species, L. cardinalis L., L. syphilitica L., L. puberula Michaux, and L. elongata Small, and ten crosses and hybrids involving L. cardinalis and L. syphilitica, were examined using two-phase descending paper chromatography with formamide-ammonium formate-formic acid as the stationary phase and chloroform-benzene as the mobile phase. The chromatogram of L. elongata showed the presence of lobinaline, suggesting its closer relationship with L. cardinalis. The chromatograms of L. cardinalis, L. syphilitica, and L. puberula were different from each other, suggesting the elaboration of different alkaloids by each of these related species. Lobinaline was present in the first species and absent in the latter two species. The L. cardinalis × L. syphilitica hybrids gave chromatograms suggesting the elaboration of alkaloids characteristic of both the parent plants.

Summary Digital simulation and plant tests have demonstrated the feasibility and the economic advantages of coordinated control of paper machines. The design of coordinated control is discussed, with examples and plant test results of paper machine coordination. On-line simulation models are proposed as an aid to coordination during certain state change, and for use in on-line estimation. The digital computer implementation of the new control schemes is described.

By the method of paper electrophoresis a comparative quantitative study was made of the sundanophilic serum lipids of two groups of persons; one group consisted of twenty-one patients who had had previous myocardial infarction, the other of eighteen women with no clinically important arteriosclerosis. The electrolipograms in all cases revealed two zones, the larger probably corresponding to β-lipoproteins, the smaller to α-lipoproteins. In the atherosclerotic group the major lipid band constituted a larger fraction of the total lipid than in the control group. The major lipid band of one-third of the atherosclerotic persons extended farther with respect to the β-globulin.

The RF values of inorganic ions on paper pre-treated with 0.25–2.0 % cellulose acetate and impregnated with various concentrations of 2-thenoyltrifluoroacetone (TTA) was studied by using acetate buffer as a developing agent. 1% cellulose acetate pre-treated paper impregnated with o.2 M TTA was found suitable for reversed phase paper chromatography. The RF values of inorganic ions were examined on the impregnated paper by using various pH's of the developing agent (0.1 M acetate buffer). Separations of PbCu, CoCu, ZnCu and FeCoNi were performed in this system.

The results obtained with freshly prepared solutions indicate that ferric ions may be adsorbed by Whatman No. 1 filter paper by a process of ion exchange. However, on standing the system becomes complicated by the diverse nature of the hydrolysis products formed. Increased adsorption takes place, apparently through the retention of hydroxy compounds of lower net charge.

The frontal method of measuring chromatographic distribution isotherms was applied to paper electrophoresis. Measurements were performed for a model coloured substance. Concentration dependence of free electrophoretic mobility, of electrophoretic mobility on paper, and of RF were obtained.

A rapid Kunkel type electrophoretic system was used to determine the effect of wetness and temperature upon the mobility of serum components. Comparison is made with a Durrum type apparatus. Variability averaged 6.5% for albumin with both techniques. Observed component mobility increases both with wetness and temperature with the Kunkel system. When corrected by use of dextran, observed mobility values are independent of wetness, but increase directly with temperature. Comment is made on mobility markers and a wetness ratio, on specimen identification by mobility alone and on the usefulness of zone electrophoresis in qualitative analysis.

The mammalian respiratory tract produces a secretion in which the major macromolecular components are mucin-type glycoproteins. High-voltage paper electrophoresis has proved a valuable research tool in studies of the formation of these glycoproteins. Separations of hexoses, amino sugars, oligosaccharides, sugar nucleotides and mucin glycoproteins are rapidly and easily obtained by paper electrophoresis at voltages of 50 to 100 V/cm. The use of high-voltage paper electrophoresis to follow amino sugars interconversions and the transfer of glycosyl units to mucin acceptors is described.

Attention is drawn to the greater optical uniformity of filter paper by reflected light than by transmitted light. The relative merits of employing reflected light and transmitted light, both on dry and transparent paper, are considered from the standpoints of ease of calculation, instrumental convenience and error. Under the conditions described here, in which an aperture of only 3 mm × 3 mm is used, the reflection method on dry paper is recommended. Measurements may also be taken on transparent paper. This causes an increase in error when transmission is used, but decreases the error when reflection is used.

A systematic analysis of keto acids and other carbonyl compounds in biological material was based on the following procedures: (1) their conversion to DNPH derivatives under mild conditions, (2) preliminary chromatographic separation into acidic and non-acidic DNPH derivatives, (3) isolation of each component by paper chromatography and (4) identification by means of rechromatography and catalytic reduction to the corresponding amino derivative. The method is quantitative for keto acids and its accuracy is between 10–20%.

Up to 20 mg of copper can be quantitatively separated from small quantities of gold, platinum and palladium, by ionophoresis on strips of paper pulp, 6 mm thick, 25 mm wide and 250 mm long. One millilitre of the hydrochloric acid solution of the metallic salts is placed on the paper, the ends of which are placed in cells containing 50 ml N HC1 and 25 ml N KC1. The paper is then moistened with N HC1. Carbon electrodes are used and are connected to a 12 volt D.C. supply, a current of about 200 milliamperes being recorded. The copper travels towards the cathode and after about 18 hours separates completely from the noble metals as a blue band about 75 mm in length. This band is cut out and used for the determination of the copper by electrodeposition, after decomposition of the organic matter by means of concentrated nitric and sulphuric acids.

Construction and use of a simple scanning device are described for locating small amounts of radioactivity on large uncut filter papers used for chromatography and electrophoresis. With this device the use of autoradiographs in eliminated from the original method for determining urinary hydroxyproline on the principle of isotope dilution. The modified method is described, and eight results are reported for the recovery of added nonradioactive dipeptide. Percentage of recovery varied from 84.5 to 111% with an average of 98.4%.

Recoveries of metanephrines from urine by three methods were compared. Ion-exchange gave higher recoveries than did solvent extraction. Best results were obtained using Zeo Karb 226 which yielded extracts in which the amines could be estimated after separation by paper chromatography.

The separation of dog serum lipoproteins by ultracentrifugation at a density of 1.063 is hindered by the failure of the high density fraction to accumulate in the bottom portion of the centrifuge tube. This phenomenon interferes with the quantitative recovery of pure low density lipoproteins. By paper electrophoresis, a lipid-containing protein with the mobility of a β-globulin was detected in the lowest layer of the centrifuge tube. Comparison of the preparative ultracentrifuge technique with that of dextran sulfate precipitation of β-lipoproteins revealed the suit ability of the latter procedure for the quantitative separation of β-lipoproteins. The dextran sulfate β-lipoprotein precipitate was shown to be free from α-lipoprotein by paper electrophoresis.

The contribution of the macroscopic mobile phase velocity profile in a paper or thin-layer strip to longitudinal dispersion in chromatography was investigated. For this purpose the dependence of the plate height on the breadth of the paper or thin-layer strip, scanned by the densitometer, was determined using Whatman W2 paper and Camag D cellulose powder. As longitudinal dispersion depends on transversal (convective and diffusive) dispersion, the latter was determined for both chromatographic techniques.

A simple paper-chromatographic method for arginase studies is described. In this method the arginine remaining after incubation with tissue extract is determined spectrophotometrically after it has been separated by paper chromatography.

A machine is described for the reproducible treatment of paper chromatograms with liquid chemical reagents. Strips of filter paper 5 cm wide are passed through the machine by two pairs of belts which grip the edges of the strip leaving the central area exposed on both sides. A film of liquid reagent is fed on to the undersurface of the paper strip by means of a roller and trough which is fed from a simple constant level device. The reagent-soaked strips pass immediately into a straight tunnel into which a stream of hot air is introduced by ports opening from manifolds running along the sides of the tunnel. The air stream is passed out of the top of the tunnel by means of an exhaust tube and fan connected to its distal end. The strips are passed out of the machine by disengagement of the belts which are returned to the starting point of the machine after being washed, and dried on their return passage through the hot air tunnel. Operating temperatures up to 150° can be achieved and are adequate for producing quantitative and complete reactions with the majority of color reagents that are useful for the quantitative estimation of substances by direct scanning of paper chromatograms (e.g. Zimmerman reagent, ninhydrin, phosphomolybdic acid). The mechanization of the treatment of paper chromatograms with color reagents improves greatly the reproducibility of the results, the evenness and reproducibility of background, and enables the successful use of color reactions which cannot be controlled sufficiently by manual methods to allow their quantitative estimation. It also enables the treatment of very large numbers of chromatograms: the present apparatus is capable of treating 40 cm long chromatograms at a rate of up to 88 per h or over 500 per day. The development, important features of design, and method of operation of the machine are described.

Reversed-phase partition chromatography was used to separate the rare earths, thorium and uranium on papers treated with methylenebis(di-n-hexylphosphine oxide), MHDPO. The separation factors between adjacent rare earths were found to increase with the acid concentration in both nitric and hydrochloric media with the larger separation factors in nitric acid. Opposite trends were observed in hydrochloric and nitric acid. In the former case the partition coefficient increased with acid concentration, but in the latter case it decreased. This was explained on the basis of the solvation energies of the cations and anions, the mass action effect and the competitive extraction of nitric and hydrochloric acid. Solvation number studies indicated a 1:1 adduct between MHDPO and the rare earth nitrates. Corresponding studies on the rare earth chrlorides gave anomalous results. It was postulated this was caused by non-equilibrium conditions.

>The various techniques utilized in the preparation and measurement of a radio paper chromatogram are reviewed. The scope and application of this technique, which combined paper chromatography and the use of radioactive tracers, have increased considerably due to the fact that the measurement of the activity is performed directly by scanning the paper with an appropriate measuring device, which is now usually entirely automatic. Consequently, a rapid comparison of the activity of the separated substances is possible. (N.W.R.)

Packaged wheat flour stored in direct contact with chlordane-treated shelf paper adsorbed with time appreciable amounts of the pesticide from the paper. Direct contact of the package with the paper was more conducive to flour contamination than it was from exposure of the flour to the vaporized pesticide components from the paper. Sorption effects of the pesticide with flour varied with the mode of exposure and the type of bag used, i.e. when the bags were in direct contact with the shelf paper, the flour packaged in polyethylene bags contained the largest amount of chlordane residue (29 ppm), which decreased about 10 per cent when packaged in single-thickness kraft paper bags and about 35 per cent in double-thickness kraft paper bags. When the bags were separated from direct contact with the shelf paper by means of open glass containers, contamination of the flour was tangibly decreased, whereby the amounts of residue found in the kraft single- and double-thickness paper bags were 0·4 and 0·3 ppm, respectively, compared to only 0·06 ppm in the polyethylene bags.

The mobilities in free solution of twenty organic ions have been calculated from their sizes, shapes and charges. From these mobilities the zone mobilities of the ions in paper electrophoresis, relative to the zone mobilities of butylammonium ion (for cations) or picrate ion (for anions), have been calculated by taking account of the extent to which the ions are retarded by reversible adsorption on the paper. Results in fair agreement with experiment were obtained for most ions having approximately ellipsoidal shapes; however, the experimental mobilities of cations and anions derived from l -amino acids are systematically lower than calculated. A comparison is made with relative mobilities calculated according to JOKL.

A detailed description is given of the construction of an inexpensive micro apparatus for filter paper electrophoresis and of methods for the micro-determination of proteins, lipoids, and cholesterol, by electrophoresis, using this apparatus.

The paper chromatography of cyclic imino acids in several systems has been studied. The color reactions, which may also be helfpul in their identification, have been examined.

A theory previously developed by the author to describe the horizontal spreading of liquids in paper has been applied to the case of a liquid rising by capillary action in a vertical strip of filter paper. The phenomenon is complicated by a surface roughness effect which had to be taken into account. The theory leads to simple expressions for the rate of rise and the distribution of liquid which are in agreement with experiment. When gravity can be neglected, the height of rise is proportional to the square root of the time. When gravity is important, the height of rise is a more complex function of time than the simple square root dependence. In addition, the liquid approaches a limiting height.

The use of visual dye markers for high-voltage paper ionophoresis has been proposed to yield reproducible ionograms and to prevent losses of peptides during purification runs. Since the relative mobility of a dye to an amino acid or peptide is not affected by temperature fluctuations during ionophoresis in vertical Michl-type apparatus, the dye is allowed to migrate to a predetermined mark on the paper that ensures that amino acids and peptides remain on the paper. Mobility data are presented for dyes and certain amino acids at pH 2.0, 3.5, and 6.5 ionophoresis.

The mechanism of peak broadening in paper chromatography is investigated by comparing the peak widths obtained in chromatography with those caused only by diffusion, for a set of amino acids of widely differing RF values and with eight kinds of Whatman paper. The results show that longitudinal diffusion occurs both in the mobile and the stationary phase in paper chromatography. The mass transfer term is composed of a contribution of unevenness of flow throughout the paper and a contribution of the slowness of attainment of the partition equilibrium between the mobile and the stationary phase. The resistance to attainment of equilibrium resides predominantly in the mobile phase.

System Optimization of Industrial Waste Treatment Design is a challenging topic in view of the ever-increasing pollution problems and the rapid development of new processes. An optimization procedure which integrates dynamic programming techniques into existing process design principles is presented. With the objective to identify the optimum combinations of various unit processes in a multistage plant, the most economic decisions are derived while meeting the ultimate design criteria. The analytical procedure utilizes the method of decision inversion in dynamic programming. A numerical example for typical paper and pulp industrial waste treatment design is presented for illustrative purposes. Many practical cost functions have also been developed for the analysis of the pulp and paper industrial wastewater treatment system which consists of different process alternatives.

Cobalt can be determined in the presence of other elements by chromatography followed by photometric scanning. The chromatographic solvent used is a mixture of acetone, n -butanol, hydrochloric acid and acetylacetone, and the cobalt spot is made visible by spraying with a solution of rubeanic acid. The filter paper is cut in strips which are scanned along their length either in a Beckman DU spectrophotometer or a Photovolt densitometer Mod. 525 at 422 mμ. The absorbance curves are plotted and the Co concentration is calculated from the area under the peaks. Chromatograms with 8 spots, each containing 0.4 — 2 μg Co, of which 4 are standards, are convenient. The coefficient of variation for the mean of a single chromatogram is 6 %. Alloys containing as little as 0.2 % Co can be analysed with an accuracy of 5 % or better.

The spectrophotometric titration of magnesium, calcium, strontium, and barium, in the visible and ultra-violet regions of the spectrum, has been investigated and a method is presented for the determination of small amounts of these elements by spectrophotometric titration using Eriochrome Black T as indicator, after separation by paper chromatography and removal from the paper with dilute hydrochloric acid. The minimum amount of each cation determined was 0.5 μ M and the procedure was applied successfully to the analysis of a dolomite, a strontianite, and a barytocalcite.

Larvae of the silkworm, Bombyx mori L., were found to feed on filter paper which had previously been heated to approximately 200°C for 15 hr. Feeding on filter paper was largely accelerated when the paper had been impregnated with sucrose. β-Sitosterol and soybean sterol, previously demonstrated to stimulate feeding of the silkworm on agar-diets, showed rather little stimulating action on paper-feeding.

Ornithine decarboxylase has been measured in midterm mouse placentas by a simple inexpensive method. The reaction vessel was a special plastic scintillation vial. The 14CO2 liberated from dl -1-14C-ornithine was absorbed by a Hyamine hydroxide impregnated blotting paper disc cemented into the vial's cap. This was released into the toluene fluor of another scintillation vial by transfer of the cap after loosening the paper disc. The incubation vial was further adapted by predrilling a hole in its side to permit addition of acid to stop incubation and drive 14CO2 out of solution. This hole was kept sealed with tape. The preference of Hyamine over ethanolamine/2-methoxyethanol mixture (2:1) was established. Also the protective value of EDTA and dithiothreitol and the deleterious effect of freezing and thawing on this enzyme were studied. Mouse placentas contain a relatively large amount of ornithine decarboxylase. This method of assay should be suitable for quantification of other decarboxylases whenever suitable carboxyl-labeled substrates are available.

The construction is described of an apparatus for horizontal paper electrophoresis with a solid water-cooled heat exchanger. The apparatus is suitable for rapid and safe routine work with paper sheets of larger dimensions at high potential gradients. The temperature of the paper can be measured and the separation process can be followed visually. The method of simultaneous multiple two-dimensional separation and the procedure of sample transfer by the printing technique are described.