dependent variable y by modifications of the electrical circuit, such as squaring, square rooting, taking logs, or plotting hyperbolas. Figure 3 is an example of several linear plots. I n each case the slope factor has been set in by the Helipot. I n this and all other examples, the printed points have been enlarged and intensified for photographic reproduction. Figure 4 shows the use of special electrical characteristics of the system. Here the translatory potentiometer has been shorted and the potential between slider and one end of the winding is recorded. The circuit has been described ( I ) . The output is a quadratic function of slider displacement measured from the midpoint. The abscissas represent integral values of n set in by the operator, and the data plotter has printed the corresponding values of the area of the corresponding circles of diameter n. I n this example, the translatory potentiometer squared the values of n and the Helipot in the swamping circuit adjusted the scale factor of 4/n, hence the printed value 4n2 is area, or
-.
?r
For more extensive variations in the functional response, the manufacturers of this translatory potentiometer supply it in the following forms. Up to three separate resistance elements can be installed within a single unit with
individual voltage take-offs actuated by the common shaft. The potentiometers can also be furnished with a wide variety of nonlinear functions and as many as three independent resistance functions can be contained in a single unit. These features afford a wide variety of functions which can be produced as a consequence of the simple motion of the slider and its pointer. The final example of performance of this plotting aid has offered much in saving time and energy. Figure 5 shows a plot of a tape which is printed out by a 100-channel pulse height analyzer. It represents the respective count rate a t each of the 100 channels representing discrete energies. The species lvere the isotopes cerium-144 and praseodymium144. The entire scan of 100 channels was 1 minute and the respective pulses were stored in a magnetic-core memory matrix. The latter is read out automatically and printed on tape. Although the spectrum is presented oscillographically for visual inspection, the printed record is more useful as a permanent record and for more detailed and precise analysis. The plot in Figure 5 was made with the data plotter in 300 seconds with a plotting interval of 3 seconds per point. This speed could be increased somewhat without too much strain on the operator. DISCUSSION
The authors have no illusions about
the superiority of this scheme for setting in data a t high speed. From some experience they are inclined to believe it better than rotary dials, decade boxes, or push-button calculator-type assemblies, unless the operator is skilled in touch typing. The ideal is a voiceactuated selector, which has interested communication experts for a long time. The problem of treating two variables, neither of which is time, can be solved by duplicating the translatory potentiometer systems and presenting the data on an x-y recorder. Although this has been done satisfactorily, no examples are given because the x-y recorder was not equipped with an intermittent print wheel, but with an ordinary pen. Consequently, the traces are continuous rectangular lines, The scheme would be eminently practical if a solenoid pen-lift attachment were added and if this could be actuated momentarily by a foot switch. ACKNOWLEDGMENT
The authors are indebted to Bruce J. Dropesky of this laboratory, for numerous pulse height analyses. LITERATURE CITED
(1) Muller, R. H.,
-4NAL. CHEM.23, 1491 (1951). RECEIVED for revierv August 27, 1956. Accepted January 18, 1958. Work performed under the auspices of the U. S. Atomic Energy Commission.
Punched Card Storage of Gas Chromatographic Data CHARLES F. SPENCER and JULIAN F. JOHNSON California Research Corp., Richmond, Calif.
b The use of IBM punched cards provides a convenient w a y to store, report, and revise chromatographic data, and it eliminates much duplication. Only data for a single compound are punched on a card. To correlate data, standard equipment is used to print tables of information obtained from the cards. gas chromatographic data, accumulated in more or less haphazard fashion, would be of greater value to the analyst if it were available in some systematic form. The problem of recording such data has been discussed by several authors ( I , 2, 6). Standard IBM punched cards provide a method whereby chromatographic data can be conveniently stored and exchanged, and made available in the ANY
form of charts for use in the laboratory. Tables can be easily brought up to date as new information is obtained. DESCRIPTION OF SYSTEM
Each I B M card is punched with data for a single compound. Tables such as Table I can be obtained from the cards with standard equipment which prints the data for each gas chromatographic column. The first three spaces show the column operating temperature. The next four spaces are for the column description code, which serves as an index to a separate record of the complete column description. Three spaces are reserved for the serial number of a specific column. The next column of seven spaces is for boiling point. If desirable, some other item of gas chromatographic data-such as calibra-
tion response, resolution, or relative band width-could replace the boiling point column. The corrected retention volume per gram (2, 4, 5 ) is tabulated in the next five-space column. Partition coefficients by Porter, Deal, and Stross (7), are listed in a column of five spaces. Six spaces contain the code for the compounds listed by the American Petroleum Institute Project 44. This code applies to a large number of hydrocarbons and a limited number of related compounds. I t s use is convenient because it permits machine tabulation of any gas chromatographic data with the physical properties of the compounds available on Project 44 punched cards. Thirty-seven spaces are retained for compound names; in most cases this will permit the complete name to be spelled out. The relative retention VOL. 30, NO. 5, MAY 1958
893
Table I.
Temp. 000 000
ooo ...
Column Description code 0002 000% 0002 . .~ 0002 0002 0002 0002 0002 0002 0002 ~
000
000 000 000
000 000 000
000
0002
0002 0002 0002 0002
000 000
000 000
Retention Vol./Gram 1.35 1.53 3.87 4.50 7.83
BP., so.
001 00 1 001 00 1 001 001 001 00 1 001 001 00 1 001 001 001 00 1 ~
~~
O
c.
-88 63 -103 71 -U 07 -78 5 -47. 70 -11.73 -0 50 9 50 -6 26 -6 90 27 85 0 88 3 72 36 07
8.27
13.3 13.8 22.7 24.7 30 4 30.9 37.1 42.0 57.5
-4 41
values ( 5 ) are listed in increasing order in the next column of five spaces. Use of a niechanical divider (S) could aid in rapid calculation of relative retention values. The standard used for the relative retention value is listed in the last column; the number refers to the number of carbons in the normal paraffin standard. Sormal paraffins were chosen as standards rather than the standards recommended a t the London meeting of the International Symposium on Gas Chro-
20% 2,4-Dimethylsulfolane
Partition
API Code
CoefT.
1.56 1.77 4.49 5.21 8.56 9.60 15.4 16.0 26.2 28.7 35.3 35.9 43 1
48 7 66 7
I
Compound
1J
2-
8 1 0
8 1 5 4
1J 1J 1J
8 23 1J 21 7 28 5 1J 8 4 1J 1 6 1J 11 3 1J 6
matography in 1956 ( 2 ) . These paraffins are readily available and cover a temperature range from -165" to 464" C. Use of a honiologous series makes it possible to transfer data from onr referrnce to another.
Ethane Ethylene Propane Carbon dioxide Propylene Isobutane n-Butane Seopentane 1-Butene Isobutene Isopentane trans-2-Butene cis-2-Butene n-Pentane 1,3-Butadiene
Relative Retention Value Stdr 0.101 4 0.115 4 0.290
0,338 0.559 0.662 1,000 1,034 1 703 1.858 2.284 2.324 2.790 3.15.5
4.318
4 4 4 4.
4 4
4 4. 4 4 4 4
4
132nd lleeting,
(4) James, A . T., Martin, A. J. P., Biochem. J . 50, 679 (1952). ( 5 ) Littleivood, -4.B., Phillips, C. S. G., Price, D. T., J . Chem. SOC. 1955; 1480. (6) Phillips, C. S.G., International Symposium on Gas Chromatography, East Lansing, Rlich., Aug. 28, 1957. (7) Porter, P. E., Deal, C. H., Stross, F. H., J . dvz. Chem. SOC. 78, 2909 11956).
1957. 12) Desty, D. H., S a f w e 179, 241 (1957).
RECEITED for review January 8, 1958. accepted February 28, 1958.
LITERATURE CITED
(1) 4mbrose, D., Keulemans, A . I. AI., Purnell, J. H., Division of .Analyti-
cal Chemistrv,
ACS, S e x YoEk, S . T.,September
High Temperature Gas Chromatography Apparatus STEPHEN DAL NOGARE and
L. W.
SAFRANSKI
Experimental Station, Polychemicals Department,
b A high temperature gas chromatography apparatus was developed for the qualitative and quantitative resolution and estimation of high-boiling organic mixtures. The partition columns were operated in the range 150" to 350°C. for the resolution of hydrocarbon, ester, and glycol mixtures. The platinum filament thermal-conductivity detectors were operated at 10" to 100°C. higher than column temperature to avoid condensation of high-boiling components. Excellent resolution was obtained on relatively short columns containing silicone grease or linear polyethylene as the partition medium. Thermal degradation was minimized by the all-glass construction and short residence time in the columns.
T
HE wide acceptance of gas chromatography in organic analysis refleets the usefulness of this technique for the separation, detection, and estimation of small amounts of gases and liquids. In general, publications
894
a
ANALYTICAL CHEMISTRY
E. 1.
du Pant de Nemours & Co., Inc., Wilmingfon, Del.
have dealt with separation. performed a t moderate temperatures (room temperature to 150" C.),ifith only a few references indicating the potentialities of high temperature applications. Cropper and Heywood ( 2 , 3) described initial work on the separation of highboiling compounds a t reduced pressures on several column packing.. Dijkstra, Keppler, and Schols (5, S) reported separations a t temperaturesup to25O"C. a t column lvorking pressures. In a later paper, they ( 7 ) indicated that allglass thermal conductivity cells could be constructed to withstand temperatures up to 300" C., but their description of the construction and operation of such glass cells is meager. The recent work of Ashbury et al. ( 1 ) and Killiams (9) also points to the potentialities of high temperature gas rhromatography. This paper describes an apparatus n hich is relatively simple to construct and has given trouble-free performance for a year. The apparatus is sensitive
to sniall amounts of organic vapors and was successfully operated a t temperatures as high as 350" C. Mixtures of compounds boiling in the range 150" to 450" C. have been easily resolved and analyses by the peak area summation method have been moderately accurate. ¶tions of high-boiling hydrocarbon mixtures, in particular, were markedly successful. APPARATUS
The assembled apparatus consists of a carrier gas source and metering device, thermal-conductivity cells, colunin and heating jacket, and the necessary circuit for detecting and recording the detector cell signal. Carrier-Gas Control. A cylinder of helium fitted with a reducing valve supplies the carrier gas a t lG p.s.i. The gas was led through gum rubber tubing to a flowmeter (0 t o 150 cc. per minute range), then t o the carrier gas preheater in the heating jacket (Figure 1). The flon-meter 11-as calibrated for each new column, or as re-
