edlled by
WALTER A. WOLF Eisenhower College Seneca Falls, New York 13148
Ion Exchange and Thin Layer Chromatography Separation of Amino Acids J e f f r e y A. Hurlbut and Thomas J. Balka Metropolitan State College Denver, Colorado 80204 We have develo~eda rapid, useful ion exchanae amino acid separation experiment and a ;apid thin layer ch&natography identification e x ~ e r i m e nfor t use in our biochemistry laboratory. One ml 01 n 2". (each) mixture of nspartic acid and arginine are p1act.d on a 2 X 40-cm column cmtaining 50g of Aml,vrlite IH I'LO cation exchange resin in the sodium f m n . The aspartic acid is r1utt.d using 0.50 hl pH 4.3 ucerate huffer. The aremine is then eluted uiine 1.0 hb KaOH. 'I'm ml frac., t i m i art. collected, and those fractions thar ,Ire a h v e a pH ot 7.0 are mixed with 1.0ml of glacial acetic acid in order to bring the pH hack tonhout S.'l'his isdonc since the ninhydrin reaction, which is used tu drtrct the amino acids, i i pH dependrnt. Each irartion is spotted on a pierr d f ~ l t e paper r and checked f i x the prwrnce iliamino a c d s mith ninhydrin. tmd a plot oi,:dor intensity versus volume is made. A m:ijor fraction containing an amino acid is the11spotted on t h e t h ~ nlayer chromatography plate, developed with 80% ethyl alcuhol, and detected with ninhydrin. Excellent separations are obtained, and the identity of the amino acids are readily determined by thin layer chromatneranhv. It reauires one hour to make the huffer and to Dack the column; two hours are required to separate and to detect the amino acids: and a little over one hour is rewired toperform the thin layer chromatography part. We ;sually make the thin laver chromatonra~hv . . . .Dart optional. Copies of the intrudurtiun I C Ichromatugraphy as w d l as the detail~draperimrnt are available from l h . Hurlhut upon requt:st.
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Compact Compacts Howard P. Williams of the University of Southern Mississippi, Hattieshurg, Mississippi, reports that an effective demonstration of the conservation of energy may he accomplished using a 9-cm glass Petri dish, water, and two 0.3 X 1 X 4 cm Lucite strips. About 40-ml of water are placed in the dish and the strips carefully dropped on the surface, where they will he supported by surface tension. If the strips have smooth edges, they will collide and slide until both pieces form one large rectangle. If a narrow end sticks to a broad side, a slight touch to place them in motion will result in the longer This column is devoted to brief announcements of new ideas in chemical education. These consist of succinct statements of the key ideas of the authors along with possible information on obtaining further material related to the subject upon request. Authors who wish to submit articles far consideration for publication should send the manuscripts (one double-spaced, typewritten page) and the supporting materials to Dr. Walter A. Wolf, Editor, Chem Ed Compacts. Department of Chemistry, Eisenhower College, Seneca Falls, New York 13148. 794 1 Journal of Chemical Education
side swinging around until the long sides are adjacent, which is the minimum surface film displacement and therefore the minimum energy configuration. This demonstration is well suited to an overhead projector. S h u War, Maung Zeya and Nyunt Wynn of the Arts & Sciences University Rangoon, Burma submit the following. Sulfuric acid and boron trifluoride are frequently used as catalysts in transesterification reactions [Paulson et al., J. CHEM. EDUC., 51,406 (1974)l. They wish to report that anhydrous aluminum chloride is as efficient as BFBas a catalyst for synthesizing esters from fatty acids, and has the advantage of a longer shelf life in solution. A suitable stock solution can be prepared by dissolving 12.5 g anhydrous Al& in 100 ml of dry methanol. Heating 2 ml of this solution and 500 mg of soap stock for 10 min in a water bath gave essentially complete esterification, as shown by gas chromatographic analysis. Clifford J. McGinn and Ramon A. Salomone of Le
Movne Colleee. Svracuse N.Y.. reoort an inexoensive method of fieparing;&thum electrodes: I'latinum wire (0.5 mm diameter) and foil (0.08 mm thick) arecommrrciallv available. The foil is cut into strips 0.7 cm wide. The foil and wire are heated to red heat in a Bunsen flame, and then one is overlapped with the other, and they are sharply hit with a hammer. (They use the bottom of a steel mortar as a base.) The wire and foil will fuse together. More than one blow may he required. The foil is cut to alength of 0.7 cm and the wire to 2 cm giving a total surface area of about 1cm2. and total weieht of about 0.15 g, which a t present market prices costs leis than five dollars. The wire end is then sealed in the end of a piece of soft glass tubing, mercury is added and a piece of copper wire is inserted below the surface of the mercurv. The uooer end of the tube may he sealed with a suitable laboratory ;eking wax. Other electrodes, e.g., silver, gold, etc. can also be prepared by hammering the heated foil and wire together.
Volume 55, Number 12, December 1978 / 795
