Qualitative Analysis of Naphthalenes by Capillary Gas Chromatography JOHN Q. WALKER' Barber-Colman Co., Pasadena, Texas
DAN L. AHLBERG Research Division, Signal Oil and Gas Co., Houston, Texas
b The analysis of naphthalenes, monosubstituted naphthalenes, and disubstituted naphthalenes through Cl2 has been investigated using combination analytical techniques. A systematic survey was made to determine the conditions required to achieve rapid, accurate, analytical results on this mixed naphthalene cut b y gas liquid chromatography alone. A gas chromatograph equipped with capillary columns, a high temperature flame ionization detector, and a special heated inlet system would resolve the 15 naphthalene compounds investigated. It was necessary to run the sample on two columns to achieve resolution of all components, but using only one column with m-bis(m-phenoxyphenoxy)benzene (BPB) gave more information than previously reported in the literature.
T
analysis of naphthalenes has been studied by a number of workers (2, 3) and in the last few years the separation of the methylnaphthalenes has been commonplace. This paper deals with the utilization of polyphenyl ether. Apiezon L and Ucon 2000 were used as capillary substrates for the separation of the first 15 naturally occurring naphthalenes through 1,8-dimethylnaphthalene. Twelve of these components boil in a 12' range and their separation using capillary columns has not previously been reported. Although we could not completely resolve all 15 components on one column, these separations are superior to those reported in the literature. HE
EXPERIMENTAL
Apparatus. A standard BarberColman Model 61-C instrument equip ed with separately controllable flash {eaters and stream splitters and high temperature flame-ionization detectors and -0.25- to 5.0-mv. recorders (2-second response time) were used in the development of this
* Present
address, Wilkens Instrument
and Research, Inc., Houston, Texas.
2028
ANALYTICAL CHEMISTRY
Table 1.
Conditions Sensitivity Carrier gas Column dimensions Column temperature, ' C. Flash heater temperature, C. Split temperature, O C. Detector temperature, O C. Sample size, p1. S lit ratio FPow rate, ml./minute
Operating Conditions Apiezon 1, 1 x 10-10 amp./:, mv.
BPB 1 x 10-10 am ./5 mv. HeEum 225 feet X 0.01 inch 175 325 290 255 0.6 125: 1 6.0
method. Sample injection was with 1- and 10-pl. Hamilton syringes. Preparation of Column. LIQUID PHASES.m-Bis(m-phenoxyphen0xy)benzene (BPB) is available from Eastman Organic Chemicals, Rochester, N. Y. Dissolve 0.9 nil. of m-bis(m-phenoxyphenoxy) benzene in 9.1 ml. of methylene chloride. Dissolve 1.0 ml. of Apiezon L (James G. Biddle Co., Philadelphia 7, Pa.) in 9.0 ml. of petroleum ether. Dissolve 1.0 ml. of Ucon 2000 (Union Carbide Co., New York 17, K. Y.) in 9.0 ml. of petroleum ether. COLUMN CLEANINGAND COATING. The capillary column was attached to a source of high pressure (0 to 1000 p.s.i.g.) effluent gas, preferably argon. A 5- to 10-ml. reservoir was placed between the column and the regulator. The new steel was washed with a t least
Helium 200 feet X 0.01 inch 156 310 305 225 0.8 200: 1
Ucon 3000 1 x 10-10 am ./mv.
HeEum 200 feet X 0.01 inch 165 350 300 215
0.8 170: 1 5.0
9.0
three separate 5-ml. charges of pentane, one 5 m l . charge of methanol, and one bml. charge of pure methylene chloride. Column was coated in the same way. Procedure. The optimum operating conditions used in obtaining the illustrated chromatograms are listed in Table I. The helium flow rates were measured with a conventional soap film meter. An inlet pressure of about 20 to 40 p.s.i.g. produced the flow rate. A clean, dry microsyringe was flushed several times with the sample to be analyzed. The sample was injected into the chromatograph through a silicone septum. The exact size utilized depends upon the split ratio and relative electrometer gain. For linear quantitative results, maximum peak height should not exceed 7 X 10" ampere with this high temperature flame detector.
Table II. Relative Retention Data
Component Naphthalene %Methylnaphthalene 1-Methylnaphthalene 1-Ethylnaphthalene 2-Ethylna hthalene 2,6-Dirnet!ylnaphthalene
2,7-Dimethylnaphthalene 1,7-DimethylnaphthaIene 1,6-Dirnethylnaphthalene
1,3-Dimethylnaphthalene 2,3-Dimethylnaphthalene 1,4-Dimethylnaphthalene 1,5-Dimethylnaphthalene 1,2-Dimethylnaphthalene 1,8-Dimethylnaphthalene
Boilinog point, C. 217.9
BPB a t 175' C. 1.00
258.7 257.9
1.71 2.17 2.17 2.28 2.32
241.1 244.6
262.3
262.8 262.9 265.6 263
268 26s 265 266
270
1.51
2.45 2.58
Ucon 2000 a t 165" C.
Apieson L at 156" C.
1.00
1.00
1.47 l.F2 2.08 2.13 2.23 2.23 2.41 2.50
2.61 2.81
2.50
2.84 2.91 3.04 3.50
2.72
2.72 2.77
3.00 3.42
1.44
1.55 2.05 2.01 2.22 2.22 2.31
2.40 2.40 2.59
2.59
2.65
2.77 3.12
I
35
39
42
45
40
51
54
ELUTION TiME-Minutes
Figure 1.
Separation of naphthalenes with rn-bis(n7-phenoxyphenoxy)benzene
RESULTS
The naphthalenes investigated included the first 15 naturally occurring compounds from naphthalene through 1,8-dimethylnapht,halene. King, Fabrizio, and Donne11 (3) by using gas chromatography obmined 10 peaks from a similar mixture while investigating the composition cf catalytic gas oils and tar distillates. Their apparatus consisted of packed columns and thermal conductivity detectors. This was a significant contributilm in the analysis
of high boiling components present in petroleum and tar oils; however, to complete the analysis, it was necessary to use other instrumental methods. Since we had already investigated the use of the m-bis(m-phenoxyphenoxy)benzene for the analysis of complex mixtures of aromatic hydrocarbons using high efficiency capillary column and high temperature flame ionization detectors ( I ) , it seemed likely that separations could be obtained on naphthalene mixtures by this technique. This liquid phase, coated on a 225-
foot X 0.01-inch column, separated 13 of the 15 compounds (Figure 1). The 1-ethyl- and 2-ethylnaphthalenes were not separated under operating conditions which gave a reasonable analysis time. Although this was better than previously reported, it was readily apparent that a substrate of different characteristicsLe., polarity--mas necessary to effect the separation of the ethylnaphthalenes. Apiezon 1, (a nonpolar substrate) was nest investigated. This capillary column, 200-foot X 0.01-inch, resolved the 1-ethyl- and %et,hylnaphthalenes, but
1M 2E
-
P
3
6
9
12
1 !i
ia
21
24
27
30
33
ELUTlO I4 T I ME- Mi n u t e I
Figure 2.
Separcition of naphthalenes with Apiezon
L
VOL. 35, NO. 13, DECEMBER 1963
2029
t
L
E a
5
o.g
-
1
44
0
--
x
1,6
L
3
E
N
0
L 0
' 2 :
1
3
'
I
6
3
6
9 9
12 12
'
dL*/(?M
2M
2,3
-u 1
15
15
Figure 3.
tailed badly on all components (Figure 2). This seems characteristic of this column with this class of compounds, since it operates satisfactorily with a paraffin mixture in the same boiling range. To achieve a separation without peak tailing, a number of substrates operable in this range (150' to 200' F.) were investigated. The Ucon 2000 200-foot X 0.01-inch column separated the 1-ethyl- and 2-ethylnaphthalenes without tailing and in a reasonable elution time (Figure 3). Retention data for these 15 components are tabulated in Table 11. I n investigating the quantitative aspects of this system, it was found that
18 18
21 21
24
~
21
30
33
36
39
42
- .-
45
EL U 1 I O N 1 IM E - Mi n ut es Separation of naphthalenes with Ucon 2000
these high boiling components could not be quantitatively split unless the temperature of the splitter tee was kept above the normal boiling point of the components being analyzed.
other complex compound mixtures, which are similar in boiling point and structure. LITERATURE CITED
&., Preprints, Division of Analytical Chemistry, 142nd Meeting ACS, Atlantic City, N. J., September 1962. (2) Fredrick, D. H., Cooke, W. D., Preprints, International Gas Chromatography Symposium, Michigan State University, East Lansing, Mich., 1961. D. 21. (3) King, R. W., Fabrizio, F. A,, Donnell, A. R., Zbid., p. 101. RECEIVEDfor review May 13, 1963. Accepted September 9, 1963. Southwest Regional Meeting, ACS, Dallas, Texas, December 1962.
(1) Ahlberg,. D. L., Walker, J. DISCUSSION
It nas possible to achieve qualitative analytical results for the naphthalenes boiling through 270' C. by correlating the spectra obtained from the m-bis(mphenoxyphenosy)benzene column and the Ucon 2000 column, since neither column would separate all the points of interest. This method (with appropriate liquid phases) may be applied to
Column Partition Chromatography of Vitamins A and D on Fluoropak 80 PHILIP S. CHEN, Jr., A. RAYMOND TEREPKA, and NANCY REMSEN Department of Radiation Biology, University of Rochester, Rochester, N . Y .
A reversed-phase column chromatographic system allowing the separation of vitamin D from vitamin A i s described. The stationary phase consisted of Fluoropak 80 impregnated with iso-octane and the mobile phase was aqueous methanol. Advantages include the use of easily volatile nonu.v.-absorbing solvents which facilitate spectrophotometry and liquid scintillation counting of eluted fractions. Examples illustrating the use of this column are presented. I.T€IOUGH
A
LARGE:
VARII, 1Y
01
techniques are available for purtition chromatography of polar conipounds, relatively few systems have 2030
ANALYTICAL CHEMISTRY
been described for such separation of nonpolar materials-e.$., vitamins A and D (4). Most methods for the latter substances rely on the theoretically less desirable adsorption systems (f ). This report introduces the u>e of Fluoropak 80 impregnated u ith isooctane as a stationary phase for the column partition chrornatographv of vitamin D. Use of this support eliminates a serious drawback of available partition methods, namely the difficulty of obtaining separated material free of the solvents used in chromatography. The mobile phase employed in moat of these studies ha. been '30% methanol. The column has been used mostly for
evaluating the purity of and for purifying radioactivity-labeled vitamin DS which may then be used for physiological or biochemical studies. In the latter studies, the Fluoropak column has been used to separate radioactive vitamin D3 from vitamin A in tissue extracts. EXPERIMENTAL
Apparatus. A 3 - f O O t glass column (12 mm. i d . ) with fritted glass disk and Teflon stopcock was used with the G M E Model V 152 fraction collector. Ultraviolet absorption was measured either on the collected fractions with the Ueckman DK-2 recording spectrophotometer or between the column and
