i- usually added during the dissolution piocess to complex some of the F- and thereby reduce corrosion. I n this case. it i; necessary to include both the bl(SOa)a and the lactic acid in the extiaction medium to prevent the hycliolysis of S b . LITERATURE CITED
(1 i Jones, H. C., "ilutomatic Couloiiietric Titrator, OIiSL Model Q-2005, Elec-
tronic, Controlled-Potential,"
Method
Sos. 1 003029 and 9 005029, TID-7015,
Sec. 1, 8-17-59. ( 2 ) Kelleg, 31. T., Jones, H. C., Fisher, D. J., ANAL.CHEY.31, 488, 956 (1959). (3) Shults, W. D., "Uranium, Automatic
Controlled-Potential Coulometric Titration Method," Xethod S o s . l 219226 and 9 00719225, ORNL hlaster Analytical Manual, TID-7015, Suppl. 3 (1-39-60). (4) Shults, \I7.D., Dunlap, Louise B., Oak Ridge Xational Laboratory, Oak Ridge, Tenn., unpublished data, 1963.
(5) White, J. C., Ross, FY. J., "Separations by Solvent Extraction with Tri-noctylphosphine Oxide," NAS-NS 3102, Feb. 8, 1961. W.D. SHULTS LOUISEB. DUXLAP Analytical Chemistry Division Oak Ridge h-ational Laboratory Oak Ridge, Tenn. Oak Ridge Kational Laboratory is operated by Union Carbide Suclear Co. for the U.8.Atomic Energy Comm.
A Mixed-Substrate Column for Gas Chromatographic Analysis of Lacquer Thinners SIR: The possibi1it.y of using gas chromatography for the complete analysis of automotive lacquer thinners and other lacquer soli-ent mixtures of siiiiilar composition-e .g.> vehicles, reducers- was recentl.7 investigated. K o r k of this type had been described preriously by Espos to and Swann ( 1 ) . who used tempcrature-programniing, by Haslani and Jeffs (Z), b y Hobden (S), and others,. This study was coii'zerned primarily with isothermal separations, as the instrument t o be used, a Perkin-Elmer V:tpor Fractoineter i\lodel 154 C (thermistoy detect,or), was not equipped for teml)erature-progranimed operation. l i t e r several columns had been tried iyithout, great success, columns with suhstrates consisting of mixture- of liquids werC tested. A part,icularly intereiting coluiiin had as a substrate a
mixture of equal amounts of didecyl phthalate and Ucon SOH13 2000 lubricant. These two liquids Tvere mixed together before they were applied to the support, as described below.
Fir e grains each of didecyl phthalate aiid Ccon 50HH 2000 lubricant werc. weighed into a beaker. About 150 nil. of methanol, in three portions, were u*ed to transfer the substrate mixture to a beaker containing 40 granis of 30 '60 Fisher Colunipak. T I i i 5 mixture 11-asstirrod and cautiously warmed until most of the methanol had evaporated. Then the material n-as transferred to a sheet of paper lying in a fume hood, d i e r e the evaporation was completed. K h e n dry and free-floning, the column packing !$as used to fill a 6-foot length of '?-inch copper tubing. All Tveighing n-as done on a platform balance. The copper tubing was cleaned with acetone follon ed by iiirthanol aiid dried hefore use.
MINUTES
L r
The Ucon lubricant aiid didecyl phthalate (Flexol Plasticizer 10-10) were obtained from Union Carbide Chemicals Co. The isothermal retention times given in Table I were obtained when the column was operated at 108' C., with a helium flow rate of 65 ml. per minute (meawred a t room temperature). Each of these retention times was obtained by injecting 1 PI. of the pure niatc>rial.
Table I. Isothermal Retention Times" for Individual Solvents
Retention Solvent time Methanol 2 2 Acetone 2.3 Ethanol 2 9 Isopropanol 3 1 Ethyl acetate 3.6 hlethyl ethyl ketone 4.0 Benzene 5 3 Methyl isobutyl ketone s.s %-Butanol 9.8 Toluene 10.1 Butyl acetate 11.9 Cellosolve 14 1 Ethyl benzene 17 4 m-, p-Xylene 19 0 o-Xylene 23 1 Cellosolve acetate 29.1 Diisobutyl ketone 30 I Diacetone alcohol 35 s Butyl cellosolve 46.5 Butyl cellosolve acetate 6i.5 In minutes, measured from point of injection t o peak maximum.
MINUTES
; I )
71
74
76
A
Figure 1.
80
ea
M
m 88 MINUTES
~1
P Z W
%
PB
IW
Isothemal separation of test mixture
MINUTES
Figure 2. mixture
Temperature-programmed separation of test
VOL. 35,
NO. 7,J U N E 1963
e
923
Table II. Temperature-Programmed Operating Conditions
Carrier gas Carrier gas flow rat>e Air flow rate Injection port and detector Starting temperature Tem erature rise Finaftemperature Final temperature mftintained for 25
40% HP,60% NP 65 ml./mn.
520 ml./min.
135" C. 50" C. 4.6' C./min. 140" C.
min.
Sample size
1 pl.
When the individual retention times were known, a test mixture was prepared, containing approximately equal amounts of each solvent listed in Table I. Figure 1 is the chromatogram that was obtained for a 10-pl. sample of the test mixture. Peak shape and resolution were satisfactory. The 95 minutes required to elute butyl cellosolve acetate completely was also satisfactory. These results were a
very considerable improvement over the separations previously obtained with other columns in this laboratory. A duplicate column was prepared, as described, from a new batch of packing material. This duplicate column behaved in the same manner as the original, indicating that the results were not fortuitous. Because of the widespread interest in temperature-programming, a few additional experiments were performed, using a n F and M Model 609 flame ionization gas chromatograph. In preparation for these experiments, the mixedsubstrate column was conditioned at 150' C. for 4 hours; then i t mas bent to fit into the oven of the F and 11 instrument. The operating conditions that were chosen are given in Table 11. Several linear temperature-programmed separations were made of the test mixture. The resulting chromatograms (Figure 2) showed little or no improvement over the isothermal trace. Seither peak shape nor over-all resolution was improved. A shift in the base line
indicated that considerable bleeding was occurring, possibly due to insufficient conditioning. The elapsed time between injection of successive samples (cooling cycle included) was about 60 minutes as compared to 95 minutes under isothermal conditions. Since the mixed-substrate column was actually intended for use under isothermal conditions, the behavior with temperature programming was not n disappointment. LITERATURE CITED
(1) Esposito, G. G., Swann, )I. H., O$c. Dig.Federation SOC.Paint Technoi. 33, 1122 (1961). ( 2 ) Haslam, J., Jeffs, -4.R.. Analyst 83, 455 (1958). (3) Hobden, F. W., J . Ozi Colour Chemists' I s s o c . 41, 24 (19%).
ROGERL. GATRELL Research Laboratories General Motors Corp. Warren, Mich. Tenth Detroit Anachem Conference, October 24, 1962.
Gas Chromatography of Polar Compounds of Low Volatility SIR: Practical problems in pharmaceutical chemistry often require the determination of polar compounds of low volatility as components of complex, and sometimes unknown, mixtures. A substantial proportion of these problems can be solved, often without resorting to preliminary separations, if they can be handled by gas chromatographic techniques. Accordingly, we have sought to extend the scope of these techniques to include the qualitative and quantitative determinations of such
compounds. This paper reports the successful handling of molecules containing hydroxyl, ether, and/or amino functional groups, and having molecular weights approaching 700.
Several techniques are available, including pyrolysis followed by determination of the fragments as described by Ettre and Varadi (1j j high-temperature chromatography as described, for
ORTHO
DI
TRI
MONC
1 Figure 1.
924
TIME
-
Benzylamines
ANALYTICAL CHEMISTRY
TIME
Figure 2.
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Benzylphenols
