Capillary Column Programmed Temperature Retention Volume Differences. T h e most difficult problem
Table V. Change in Isothermal Retention Volume Constants with Column Length
in qualitative analysis encountered b y t h e gas chromatographer is t h e identification of peaks eluted from capillary columns. Small sample size employed on capillary columns does not permit the use of chemical reagent to detect functionality nor ran enough material be collected upon elution to afford analysis by auxiliary physical methods. The extension of the concept of retention volume constants to capillary column ionization detection systems greatly enhances the usefulness of such systems. A study of the programmed temper-
6-Foot 12-Foot OPN/ OPN/ 6-Foot 6-Foot Compound Type CW-4000 CW-4000 Alkanes 0.8 1.7 Thiols 1.4 5.1 Alkyl benzenes 1.6 6.4 Thiaalkanes 1.7 6.0 Acetates 2.0 8.1 Alcohols 2.2 8.6 Aldehydes 2.8 11.7 hlethyl ketones 3.1 12.3 (Temperature: 125' C.)
Table VI.
Identification of Hidden Components
ISOTHERMAL VR (CW-4000) (CW-2Olf) Iz' 2 1 cm. 7.8 3.7 2 1 4 5 2.3 V R
Butylbenzene Heptanal
PROGRAVMED
Type Alkyl benzene Aldehyde
TEMPERATURE V R
VIR(OPN) (CW-4000) 9 8 8 3 7 7 8 3
Dimnylether Dodecane
Table VII. Programmed Temperature Retention Volume Differences 100-Foot stainless steel capillary columns coated irith OPN and CW-4000 (30" C t o 150" C. a t 7 " per minute) -1VR
Compound T) pc Alkane. Dialkyl ethers Aldehydes Alkyl acetates Ketones .41kyl henzenes Thiaallxtnes A41cohols
(AT.). Cm. -3 0 -0 6 0 i 14 2 1
2 2 2 4 -3 5
Compounds Evaluated C6FC12 c6-c12 C1-C3 CrCs C&*
cs-cio c3-ci c2-CG
The fwt that two components are eluted simultaneously on the Carbowax 4000 column is, of course, revealed b y the a p p e x m c e of an extra peak on the chromatogram from the Carbowax 20-11 column. Calculation of the rctention volunie ratio then identifies the compound types, and subsequent identification is made in the usual n a y from the log retrntion volume vs. carbon number plots. Similarly, for programmed temperature operation, diamy1 etlicr and dodecane elute from the Carbon ox 4000 column with the same retention x olume. Retention volumes are different, however, on OPK. I n this case, calculation of the retention volume difference identifies the functional grouli type of the compound.
AVR
1 5 -0 6
Type Ether Hydrocarbon
ature retention volume-carbon number plots on 100-foot stainless steel capillary columns coated m-ith Carbon ax 4000 and P,p'-oxydipropionitrile for a number of homologous series showed t h a t parallel slopes nere obtained (see Figure 5 ) . The programmed temperature retention rolunie differences are summarized in Table T'II. The retention volume differences are sufficiently well separated to permit characterization of the compound type. I n spite of the excellent separability and high sensitivity, capillary columnionization detector gas chromatographs have found only slight utility in the analysiq of multicomponent, heterofunctional mixtures because of the inability to identifj- peaks. Xow,
through the use of retention volume constants, qualitative data can be obtained conveniently. ACKNOWLEDGMENT
The authors are indebted to Robert
SV. Slater for his contributions to the experimental work. LITERATURE CITED
(1) Anderson, D. M. W.,Duncan, J . L., Chem. & Ind. 1958, 1662. (2) Bellis, H. E., Slowinski, E. J., Jr., J. Chem. Phys. 25, 794 (1956). (3) Brown, I., iVature 188, 1021 (1960). (4) Dal Kogare, S., Langlois, W.E., ANAL. CHEM.32, 767 (1960). (5) Desty, D. H., Whyman, B. H. F., Zbzd., 29, 320 (1957). (6) Drew, C. M., RlcXesby, J. R., Smith, S. R., Gordon, -4.S., Zbid., 28, 979 (1956). ( 7 ) Gohlke, R. S., Ibzd., 31, 535, (1959). (8) Habgood, H. R., Harris, W.E., Ibid., 32, 450 (1960). (9) Heaton, IT. B., Kentmorth, J. T., Ibzd., 31, 349 (1959). (10) Holmes, J. C., Morrell, F. A , , A p p l . S p d r y . 1 1 , 86 (1957). (11) James, A . T., Research (London) 8 , 8 (1955). (12) James, A. T., Xartin, A. J. P., Brit. Med. Bull. 10, 170 (1954). (13) Kovats, E., Helv. Chzm. Acta 41, 1915 (1958). (14) Lewis, J. S., Patton, H. W., Kaye, \v. I., ANAL. CHEM. 28, 1372 (1956). (15) .Littlewood, A. B., Phillips, C. S. G., Price, D. T., J . Chem. SOC.1955, 1484. (16) McCreadie, S. IT. S.,Killiams, A. F., J . A p p l . Chem. (London) 7, 47 (1957). (17) Rlerritt, C., Jr., Kalsh, J. T., ANAL CHEJI.34, 908 (1962). (18) Pecsok, R. L., "Principles and Practice of Gas Chromatography," pp. 137-8, Wiley, Sew York, 1959. (19) Pierotti, G. J., Deal, C. H., Derr, E. L.. Porter. P. E..J . Am. Chem. SOC.78, 2989 (1956). (20) Sullivan, J. H., Kalsh, J. T., 'Llerritt, C., Jr., ANAL.CHEM.31, 1826 (1959). (21) K'alsh, J. T., RIerritt, C., Jr., Zbid., 32, 1378 (1960). (22) Wehrli, h.,Kovats, E., Heli,. Chim. Acta, 42, 2709 (1959). RECEIVEDfor reviex October 5, 1961. Accepted May 14, 19G2.
Correction Flame Photometry Using Oxycya nogen Flame I n this article by J. W. Robinson [ANAL,CHEM.33, 1226 (1961)j, some of the wavelengths quoted in Table I, pages 1228-9, are incorrect. listed below :
CASBOU
hLhrBEQ
Figure 5. Programmed temperature retention behavior of various homologous series on capillary columns B,p '-oxydipropionitrile
______
-
Carbowax 4 0 0 0 Temperature programmed from 150' C. at 7 ' C. per minute
30'
C.
to
Element Ba Ga Au Mg Hg Pt Ag Zn
Wavelength Quoted 4534 4300 4837 4994 4536 2922 3282 2183
They are
Correct Wavelength 4934 4033 5837 Delete 4358 2929 3383 2138
VOL. 34, NO. 8, JULY 1962
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