James M. Miller Drew University Madison, New Jersey 07940
Bibliography of Experimental Gas Chromatography
Because of its low cost and great usefulness, gas chromatography has become a popular tool in educational institutions. A number of homemade instruments have been described as well as many educational experiments. It is the purpose of this paper to summarize this work. While it would be impractical, if not impossible to include all relevant publications, the bibliography does include all papers published in THIS JOURNAL. The first and only review of this type to be published in THrs JOURNAL was in 1956 (2), only five years after the introduction of gas chromatography. The technique has advanced considerably since then and many of the older papers are not too useful. Therefore the bibliography is presented in chronological order. In this paper the instrumentation will be discussed first, followed by the experiments. In a paper written for educators it is worth noting that the term "vapor phase chromatography" (vpc) is incorrect. Unfortunately, it is still in use even though an international symposium in London in 1956 suggested "that the term gas chromatography be used to describe all chromatographic methods in which the moving phase is a gas, that the term vapor phase chromatography be no longer employed" (4). Ironically, the proceedings of that symposium were published under the title Vapour-Phase Chromatography" (see ref.
(4)). Instrumentation Costs
The cost of building a homemade instrument is reported to vary from about $40 to $250. By comparison, some simple inexpensive chromatographs are now available which cost from $400 to $800.' I n either case one has to add a readout device (potentiometric recorders cost from $200 to $1000) and a gas regulator (about $50). Also many of the homemade instruments described in the references do not include the cost of a dc power supply (required for a thermal conductivity detector) or an amplifier (required for a flame ionization detector). There are a few detectors which are very simple and inexpensive which are intended for demonstration purposes only. These will be discussed first, followed by the two most common detectors, the thermal conductivity detector (TCD) and the flame ionization detector (FID). Demonstration Apparatus
Cowan and Sugihara (9) described a demonstration apparatus using hydrogen as t,he carrier gas so that the
'Educationalinstruments are available from A.R.F. Products, Inc., Carle Instruments, Inc., and Gow-Mac Instrument Co. 306
/ lournol of Chemical Education
column effluent could be burned. Sample components were detected by noting the changes in the nature and the height of the flame. For halogen containing materials a copper wire was placed in the flame and the characteristic green color noted. A modification of this procedure uses oxygen or air as the carrier gas, mixed with carbon monoxide prior to ignition (18). These authors also converted their detector to a semi-quantitative flame photometer by using a light meter to monitor the flame intensity. This detector system can also be adapted to permit recording. The flame temperature can be measured by a thermocouple placed slightly above the flame. This arrangement was first described by Scott (1). More recently Scott described a simple pressure sensitive device which can be used for demonstration purposes (32). A glass tube containing a soap film is inserted on a tee near the end of the column. The film remains immobile except when a sample component passes that part of the column. Then it moves in proportion to the pressure change associated with the passage of the sample component. One other well known demonstration apparatus was described recently by Silberman (39). Carbon dioxide is the carrier gas and it is bubbled into sodium hydroxide solution a t the column exit. Unlike the COz, most sample components are not absorbed by the base and their presence can be detected and their volumes measured on a semiquantitative basis. Instruments Using Thermal Conductivity Detectors
The simplest common detector which provides a signal which can be recorded is the TCD or katharometer. The detector element is incorporated into a wheatstone bridge circuit and can be either a resistance wire, a thermistor, or a glowplug. The use of a single element is not recommended and two or four element bridges are preferred. The carrier gas used with this detector should have a high thermal conductivity (helium or hydrogen) although some references report the use of nitrogen. The housing for the detector elements is usually a metal block although in some cases the detector element is simply inserted into the end of the column. Several instruments have been described which use commercial detectors (5, 7, Sf), which cost about $100. Alternatively a commercial detector element (resistance wire or thermistor) can be purchased and inserted in a detector block of one's own design. Such devices have been described by Thomas and Smith (lo), by Sicilio, et al. (15), and by Ceresia and Brusch (21). Another possibility which has not been described is to insert a commercial detector element into one arm of a tube tee.
Although is is fairly difficult to make a resistance wire detector "fron~scratch," two such devices have been described (5,6). A much simpler way to get a satisfactory resistance wire is to use the filament of a small lamp. Such a detector has been described by Birrell ($8), by Lowell and Malamud @4), and by Stong (35). Any of these three would be an ideal detector for a simple chromatograph. Lowell and Malamud's paper is especially recommended since their detector contains four elements, and a parts list and circuit diagram are included. The other type of TCD uses model airplane glowplugs as the detector elements. This detector was first described by Felton and Buehler (8) and later by Herhener (28). Felton noted that an advantage of this detector was its high temperature capability. Instruments Using Flame Ionization Detectors
It is probably easier to build a FID than a TCD. However, the FID requires hydrogen and air in addition to the carrier gas and it requires a high impedence amplifier. Several differentFID designs have been suggested (17, SO, 37, 58). Note that the collector electrode can be made either the anode or the cathode, but that the former is usually more satisfactory. Also, for most amplifiers it is desirable if the collector electrode is kept at virtual ground. If so, it is necessary to keep the other electrode insulated from the detector case to prevent accidental shocks. A modification of the simple FID which has been suggested by Nowali and Malmstadt (46) permits it to be used as a sodium thermionic detector or an electron capture detector by changing the electrodes. Their basic design resembles that of Bradley and Falconer (17). The type of high impedence amplifier which is needed for the FID mmmonly uses an electrometer tube as the first stage. Although many such circuits have been published, a few appear in the literature cited ($5, 50, 58). The circuit described by Malmstadt, Barnes, and Rodriguez ($3) is particularly useful because it can be added to a commercial recording pH meter. Purpose of Experiment Quulilatiue Analw* Introductory Introductmy Qual. Temp. & flow Q u d ; variables Qua1.G Iden. of oils Quanlitalive Some variables Area integration, response factors OIoonie Reaetio7Ls ~ecomposition Dehydration Friedel Crafts Kinetio study Ssilard-Chalmers Miseelhneous Fractionating column efficiency Phase diagram Det. of activity
Sample T~me
Other Equipment Details
For many chromatographic experiments it is necessary to put the column ahd/or the detector into an oven. While inexpensive commercial ovens can he used, a variety of homemade ones have been described. Most of them are operated with a variable voltage transformer which puts a constant amount of heat into the oven and maintains it at a specified level above ambient temperature. The ovens which have been described vary from an oil bath (5), a Dewar flask (7), a four inch stainless steel polished case (uninsulated) wound with nichrome wire (10, a four inch steel pipe (insulated) wound with nichrome wire (15), a wooden box either wound with nichrome wire ($1) or supplied with a cone heater ($8, 55) to steam pipe covering wound with nichrome wire ($8). Two devices have been described in ~ m JOURNAL s for changing the temperature of the oven during a run and thus accomplishing programmed temperature chromatography. One is a motor driven transformer originally designed for use in DTA (14), and the other uses a capacitanceoperated relay (46). The injection port is usually quite simple and may be heated independently of the column oven. Usually it is either a serum cap on a glass tube tee (3, 9, el), or a rubber septum held by a nut on a metal'tube tee (7, $8, S8,39). One special type is a brass cylinder which also serves as the column holder ($7). Many of the references cited contain information about packing columns and other experimental details. A special motor driven device for packing columns has been described by Ven Horst, et al. (15). Column packing and other details can also he found in the hooks by Miller (51) and McNair and Bonelli (48). Experiments
The experiments are summarized in the table according to the purpose of each. The liquid phases that are listed may not be the best ones for some of. the separa-
Liquid Phase
Length (ft)
Ref.
4 4
8 Isomeric Hexanes Hydrocarbons, alcohols Pesticide residues Esters of fatty acids
6
4 6
6
Ether, acetone, C&CL Hydrocarbons
DNP, silicone Apieson L
Acetone, pentsne Pentanol Butyl chloride benzene Alcohols metals Alkyl h'lides
(a$mina) Silicone Polyester DOP Silicone, Parapak Q
+
Benzene, toluene Benzene, toluene Hvdrocarbons
6
5 10 10 8 11 6
5 Carbowax DNP
8
3
Volume 47, Number
4, April 1970 / 307
tions, and hence they should not he used without further consideration. For example, the detergent Tide is readily available and its use is novel, but it is not a very good stationary phase. The solid support is not specified in the tahle because it is not critical for most of these experiments. I t does become important when one is running highly polar materials, especially those that can hydrogen bond. Details about solid supports can be found in the papers by Ottenstein (20). The column diameter is not critical either. Most of the work reported was done on '/d-in. 0.d. columns. The experiments recently described by Steinfeld (47) are not listed in the table. They include a wide variety of separations like oxygen and nitrogen in air on a molecular sieve, ortho and para hydrogen on alumina a t 7g0K, the analysis of liquor, and a study of gas diffusion. References given in his paper provide further details. Many new laboratory manuals contain these and similar experiments. A bibliography listing over 40 experiments taken from 15 texts is available.2 For qualitative analysis, the paper by Walsh and Merritt (13) should be consulted. It describes a simple apparatus for use with organic functional group tests. A final reference (44), describes a flask for use in collecting samples. Literature Cited (1) (2) (3) (4)
SCOTT. R. P. W . . Nature 176,793 (1955). C. B.. J. CHEM.EDDC.33.485 (1956). LOTZ.J. R.. AND WI'LIN~HAM. DRENNAN, D., A N D K E M B AC.. ~ , J. CHEM.EDIIC.33,490 (1956). DBSTT.D. H. (Edztor). "Vapour-Phaae Chromatography." Aoademic Press. New York. 1957, p. xi. S. A,, J. CXEM.EDUC.34,194 (1957). (5) GREEWE, (6) RYCE.S. A., KBBIRLE.P.. AND BATCE.W. A,. And. Ckm. 29, 1386 (1957).
"ow-Msc Instrument Co., 100 Kings Rd., Madison, New Jersey 07940.
308
/
Journal of Chemical Education
(7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20)
G o m n e , R. 8.. A w l . Chem. 29, 1723 (1957). FE~TON, H. R., ANDBDBHLER, A. A,. And. Cham. 30.1163 (1958). C o w n ~ P. . J.. m n S u a ~ w s * J. . M.. I. CHEM.EDUC.36. 248 (1959). T x o ~ ~C.s 0.. , Ann SMrrn, H. A,. J. C a m . Eooc. 36,527 (1959). R o ~ e n . J N. . Jn..Anol. Chem. 32,447 (1960). WALBH,J. T.. A N D M=RRITT.C. JR.. And. Chem. 32, 1378 (1960). YEN HORBT,SR.H.,V m Honm. H.. AND O'CONNOR,K., J. CXEM. Eonc. 37,593 (1980). M*R=owme. M. M.. BORYT*,D. A,, A N D CAPRIOL&G., J. CHBM. Eooc. 38, 96 (1961). S ~ c m o F.. . BULL.H.,PAWER,R. C., A N D HNIOET.J. A,, J. CIEW. Eoac. 38, 508 (1961). S c x l ~ s ~ P m N zA. a . C. W.. J. C x m . Eooo. 39,310 (1962). B n m ~ e rL. , L. T..A m F*Lcosen, W. E., J. Sci. Inatr. 40,606 (1963). M c L a m , J., AND PAuaox, P. L., J. Cmsu. Eooo. 40,539 (1963). K e n w o n ~ ~S.. r . M m m , J. M.. AND M A R T I R ~ D., . J. CHEW.EDUC. 40. 541 (1963). OTTEN~TB D.. ~ .J. Qas Chvomalo~1 141, 11 (1963). See alaa: "Advances in Chrom~tography," Giddings and Keller, editara. Marcel Dekker, New York, 1966, Vol. 3, p. 137; J. Gas Chvomoloo. 6, 129
\.""-,. II0F.P)
(21) C n n ~ s 1 G. ~ . B..rao Bnoson, C. A,, Amcr. J. Phom. Educ. 28, 194 (1964). (22) H m n m s n . R. E.. J. C m n . Eom. 41. 162 (1964). (23) MALMBTADT. H.V., BAANES.R. M., A N D R O D R I ~ D P. BA,, ~ J. CXEM. Enuc. 41,263 (1964). (24) D n ~ ~ r n A. m C., , J. C h m . EDDO.41,278 (1964). (25) MILLER,J. M., J. CHBM.EDUC. 41,413 (1964). (26) AULT,A,. J. CHBM.EDVC.41,432 (1964). (27) A m o m , A. J.. A N D LORD,K. A,, J. Sci. Indtr. 42,47 (1965). (28) B I R ~ E LA,. G . Chcministry 38. 141, 26 (1965). (29) DOBBINS, M. F. (IV). Chcmislry 38 [ I l l , 27 (1965). (30) H D ~ H ED. B ,E. P., J. CHEM.EDUC.42,450 (1965). (31) MILLER.J. M.. "Experimental Gas Chromatography.' 2nd ed.. GowMac Instrument Co.. Madison. N. J.. 1965. (32) S c o n . R. P. W..Anal. Chem. 37, 1764 (1965). J. A,. NICHULA~. J. B.. AND RACK,E. P., J. CREW.EDUC. (33) MESRIOAN, 43, 543 (1966). (34) LOWELL, 8.. AND M A L A M ~H., D . J. CHEM.EDDC. 43,660 (1066). . L.. Sn'.Am. 214 161. 124 (June. 1986). (35) S ~ o n aC. (36) Jonrsron. D. O., J. CHEM.EDVC.44.33 (1967). (37) MOR(IENTHALER;L. P.. J. CHBM.EDVC. 44, 325 (1967). See alao: McKee-Pederaon, "Application Notes," I1 1331, (1967). (38) S ~ o a aC. , L., Sei. Am. 217, 283 (1967). R.. J. CXDM.EDDO.44. 590 (1987). (39) SILBERMAN. (40) PARDUE. H. L., Bmxm, M. F..ANDBARNEB, J. R., J. C H ~ W EDDC. . 44,
OG,, """
(41) M o r s a ~N. . J.. AND SWAIN, H. A. JB.. J. CXEM.EDDO.45,48 (1968). (42) COYER,R. E., I. CHEM.EDDC.45.120 (1968). (43) W m c a ~ a n ,M. A.. AND S O E M ~ ~ T - B L ~F.. E K J. , Cmw. E n m . 45, 150
BBO?&I, E:'J., - B & ' G ~ s Chromatographu:' (48) McN*m, H. M:. A" (5th ed.). Varian Aerograph. Walnut Creek. Calif.. 1969.
