Microcheniical Laboratory of the Biochemical Research Foundation of the Franklin Institute HERBERT K, ALBER .AND J. H-IRhSD, Biochenlical Research Foulidation. Philadelphia. Pa.
T
HE construction and function of a number of niicrochenii-
cal laboratories have recently been described (4, 5 , 6 , 9, IO). These articles distinctly show the importance of niicrochemical methods in various fields of research, and indicate the necessity for adequate facilities in carrying out such delicate analytical work. Recognizing the value of applied microchemistry for biological research, the Biochemical Research Foundation of the Franklin Institute established a special group for the purpose of carrying out most of the analytical work by means of micromethods. An extensive report on the construction and function of this microchemical laboratory has been published (3, 7 ) . A condensed review is given here, indicating the principles accordinn to which the laboratorv has been set up. I n ilanning t'he laborato;y, and .electing the equipment, careful consideration was given to the requirements of the foundation (8),so that the microchemical work could be correlated to that of the various research groups. The aims and purposes of the microchemical department are as follows: 1. All new compounds or other products resulting from the research of the different groups are analyzed by the department, excepting those cases in which the analytical work constitutes a n integral part of tlie research problem. Because most of the problems are related to the fields of organic and biological chemistry, the need for organic analytical procedures was apparent. Severtheless it was decided to include facilities for carrying out the more important qualitative and quantitative inorganic procedures as ivell. The need for microchemical methods arises not only from the frequent scarcity of material (often less than 20 nig.), but' also from t'he time saving which can be effected by microanalybis. The latter is especially important when the different steps of a given reaction or fractionation must be closely followed a t frequent' intervals.
2 . In addition to carrying out the above analytical a.ork. tlie microchemical department functions as an advijory g~oup in analytical problems in general. 3. Research in the field of applied microchemistry is also carried out. Frequently the efficiency of standard procedures must be controlled, particularly when impure samples of biological origin are being analyzed.
Description of the Laboratory The microchemical laboratory is located on the fifth floor of an office building. The rooms had not previously been used for chemical work; this was of some advantage, since special equipment could be designed and arranged so as to utilize fully the available space. Proper distribution, ac-
Room Z a u a n t ,t a t w e Jrganic Analys , l . .
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cessibility, and convenience of laboratory furnishings and special apparatus are of primary importance in this type of work. Only in this way can strain to the microanalyst be avoided and high working speed maintained. Figure 1 shows the floor plan of the laboratory, which is divided into five sections: Room A is for preparative work, decomposition of samples including Kjeldahl procedures, and all manipulations which require a hood, so as to avoid corrosion of finer apparatus in the other rooms. Room B, for qualitative microtechnics and microscopical investigations, serves at the same time as an office and reference room. All inorganic and organic qualitative and semiquantitative analyses, mechanical separations under the microscope, and technics connected with chemical microscopy are carried out here. Room C is used for drying samples in vacuo, filtration procedures in quantitative work, and microtitrations. Room D is separated from room C by a plyviood \Tall only, and serves as a balance room. Room E is equipped for quantitative organic elementary microanalysis and electrolytic procedures, and has ample space for special apparatus which can be set up if needed (benches 2 and 5 in Figure 1).
A few of the furnishings in this laboratory are described below in some detail, as they may be of special interest t o other microchemists. WORK BENCHF O R QUALITATIVEMICROTECHNICS. For all qualitative inorganic and organic microchemical analyses and micropreparative procedures, a unit has been formed consisting of a microscope table and a work bench. This unit, located in room B, is arranged so that all necessary equip-
FIGGRE 2.
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ment is conveniently a t hand, and unnecessary movements and distractions can be avoided. This is of particular importance in qualitative microanalysis, since otherwise the advantages over the ordinary methods become questionable. Nearly all samples submitted for quantitative analysis are subjected to a preliminary qualitative or semiquantitative organic elementary analysis, so t h a t the correct procedure, sample weight, etc., may be selected according to the amounts of constituents and impurities present (1). The microscope table was built by E. H. Sheldon and Co., Muskegon, Mich., according to drawings obtained through the courtesy of the Bell Telephone Laboratories, Inc., New York, N. Y. The work bench for all qualitative technics was specially designed (Figure 2 ) and is rather unusual. On its right side a hand centrifuge with a special head for micro centrifuge cones and capillaries is fixed to the table, the top of which is covered with gray linoleum. The centrifuge is surrounded with a protecting shield and cover; its projecting handle is set into a small quadrant, thus eliminating accidental knocking. Two “music room” bulbs are mounted on the under side of the lowest shelf for reagent bottles, etc., providing uniform illumination without shadows from the fingers and body of the analyst. On the left side a special reagent block with 5 tiers of holes serves for vials filled with various reagents for qualitative organic analysis. The drawers of the table on the left side are arranged for incoming samples, for all small apparatus in the spot test technic, and for working tools. Over the kneehole is a wide drawer for slides, cover glasses, forceps, etc. On the right side are 7 narrow compartments containing the liquid reagents for the qualitative organic elementary analysis, capillaries, pipets, glass rods, platinum loops, wires, and spatulas, etc. In the section of the bench below the centrifuge are drawers, one of which is provided with a special rack for the various micro centrifuge cones; the other
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draTTers contain separatory funnels, specific gravity pipets, and microapparatus for extraction, sublimation, and distillation, all of which are thus kept dust-free and ready for immediate use.
according to the type of titration, and provides for the future use of ultraviolet light necessary with fluorescent indicators. Figure 4 illustrates this table.
WORK BEXCHFOR SUCTIOS,FILTRATION, ASD T'acuuir DRYING.A suction plate similar to the one described by
Inserted in the top are tiyo removable glass plates which are illuminated from underneath. The two bulbs on each side are connected to one sliding resistance, which allows dimming the light gradually. Colored light filters of Pyrex glass are interposed in the slits below the top by means of wooden holders. The color effects help considerably in observing weak end points by producing sharper color contrasts. The heat, from the bulbs is carried off by means of slits in the side walls of the table. Accurate readings of the meniscus of the standard solutions in the microburets is made easier through two uniformly illuminated glass plates which are mounted in the back of the burets. Besides the standard microburets, other micro-. or macroburets can be supported by clamps from the three metal racks, which also serve as supports for covers-e. g., when work in ultraviolet light is to be done.
Clarke and Hermance ( 5 ) is inserted in the linoleum-covered table top of this bench in room C (Figure 3). In the vacuum line leading to this plate lie two outlets to which are connected the different filter devices and the filter tubes in their drying blocks as used in quantitative microanalytical ITork; a few of these arrangements are shoTvn in the center of Figure 3. Six needle valves allow the independent use of each of these suction areas. The high-vacuum pump is located in the right cupboard of the bench on a wooden case, xhich re 6 rubber stoppers to reduce the otherwise very annoying tions through the floor. h few permanent pieces of equipment are placed on this table, one of which is the Abderhalden dryer on the extreme right side. It is provided with a special metal rack designed by Alber ( 2 ) for opening and closing charging tubes with ground caps without bringing the sample into contact with moist air. Another drying apparatus for use with high vacuum, described by Unterzaucher (ff), is supported by one of the Kewaunee buret rods with standard taper, TThich are successfully used on the other tables. In this laboratory it is very important to dry the samples under carefully controlled conditions, since many of the biochemical products are extremely hygroscopic; only by preventing any access of (moist) air can accurate results in the various determinations be obtained. The big shelf carries, in special metal holders, the micro wash bottles, the flasks with interchangeable ground joints which contain liquids of constant boiling point for use with the Abderhalden dryer, etc.
TITRATION TABLE.For microtitrations a special table has been designed for use under widely varying conditions. This equipment offers the possibility of changing the illumination
FIGERE 3.
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BALASCEROOM.This room should be air-conditioned, with a consbant humidity of about 50 per cent, a constant temperature of about 24' C., completely dust-free, and free from vibrations, in order to provide ideal surroundings for such delicate weighings (6, 9, IO). It was impossible to provide all these features in t'he laboratory a t the present time, the only precaution taken being the installation of a filtering device (-&-Pilot) in room B for the removal of excessive dust from the city air. For the microbalances :t space centered in the laboratory was selected and protected as far as possible from the influence of sudden temperature fluctuations b y separating it from the other room with a plywood wall and a gliding door. The vibrations which, for instance, come from the motor for compressed air on the floor just above the balance room are eliminated by the special construction of the balance table.
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each vessel and its cclunterpc&e, bo that they are ready for immediate weighing when needed and are protected from
dust.
Efficiency of Laboratory I n the opinion of the authors, the above construction fulfills all the requirements for a very useful and efficient microchemical laboratory. The \-arious pieces of special equipment are, naturally, not without precedent. The experience leading to this final form of construction was obtained through setting u p five other microchemical laboratories for various purposes in different countries and b y visits to well-establishetl microchemical laboratories in this country. It is hoped that this abstract of the original paper (3) mill be helpful to other workers n h o may be concerned with the problem of equipping a microchemical laboratory. The best proof of its efficiency is the statement in a report given by the director of the foundation ( 7 ) ,that all incoming problems, which vary considerably because of the wide scope of research done in this foundation, can now be solved without delay.
Literature Cited 11) Alber H. K , lecture presented at the Organic Symposium of
the American Chemical Society, Richmond, Va., December, 1937. ( 2 ) Alb&, H. K., Mzkrocheml’e. in press (1938). (3) .%lber, H. X., and Harand. J., J . Franklin Inst., 224, 729 (1937). (4) Clarke, B. L., IND. EXG.CHEM.,23, 1301 (1931). (5) Clarke, B. L., and Hermance, H . W., Ibid., Anal. Ed., 7, 218 (1935). (6) Kirner, IT. R., Ibid.. 5, 363 (1933). (7) McDonald, E., J . FrankZin Inst., 225, 164 (1938). (8) McDonald, E., Repts. Biochem. Research Foundation, Franklin Inst., Vol. 111, 1934-35. (9) Niederl. J. B., and Niederl, V., “Micromethods of Quantitative Organic Elementary Analysis,” p. 219, New Pork, John Wilev & Pons. 1938. (10) Peterson, J. B., and Pchoeffel, E . IT,, IND.ENG.CHEM.,Anal Ed., 10, 172 (1938). (11) Unterzaucher, J.. .%fikrochemie, 18, 315 (1935).
FIGURE 4. TITRATION TABLE
This table has an oak top 2 inches thick, which is supported by two triangular iron brackets. These are inserted into the wall and partly insulated from vibrations of the wall by cork plates 1 inch thick. Between the table top and the iron brackets, lead sheets 0.5 inch thick are interposed to break up remaining short shocks and vibrations coming from the wall; the table top itself has no direct contact with the walls. In order to take care of the long vibrations and short shocks which are not absorbed by the above-mentioned breaking devices, the microchemical balance has further supports: a rubber pad, 1 inch thick, is placed directly on the table, and a heavy marble plate rests upon it. Onto the marble d a t e are glued. in the oosition of the feet of the balance, three-metal rings filled wifh rubber, on top of which are placed round aluminum sheets having no direct contact with the met,al rings, the whole serving as a shock.free support. To prevent vibrations which may result from writing directly on the balance table, classroom-type chairs with side arms are used for recording the results at the balances. With these arrangements, no disturbances in weighing at the two Kuhlmann microchemical balances are noticeable.
RECEIVEDh l a y 23. 1938.
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JVORIi BENCHWITH DR.4WERS FOR STORING W E I G H I K G VESSELS .4KD CORRESPOKDIKG TARES. A very useful arrangement for
keeping the micro weighing vessels and the corresponding counterpoises in place is incorporated in the work bench in the balance room (Figure 5). It is a general rule in microanalysis to tare any of the vessels to be weighed on the microchemical balance with a n object which has similar shape, the same density, and a weight about 1 to 2 mg. less than the vessel. With three microanalysts, the unavoidable accumulation of the numerous tares in the balance cases and around the balances could easily result in mistakes. The drawers of the work bench in Figure 5 contain wooden blocks with openings corresponding in shape to
BENCHWITH DRAWERS FOR STORING WEIGHINGVESSELS FIGURE 5. WORK AND CORRESPONDIXG TARES 40 6
