Gas chromatography and mass spectrometry of acetonitrile, furan, pyrrole, paraffins, and other aromatic organic compounds of biological significanc

Oro, J.

Updegrove, W. S.

Zlatkis, A.

English

NASA Technical Reports Server

GAS CHROMATOGRAPH -QUADRUPOLE MASS SPECTROMETRIC 
ANALYSIS OF ORGANIC COMPOUNDS 
-, 
W. S. Updegrove, J. O r o ' ,  and A. Zlatkis 
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Chemistry Department 
University of Houston, Houston, Texas 
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6) 
ABSTRACT 
An a n a l y t i c a l  gas  chromatograph-mass spectrometer  
system w a s  designed and b u i l t  us ing s tandard  simple sub- 
systems, i nc lud ing  a s m a l l  quadrupole mass f i l ter ,  t o  
analyze mixtures  of organic  subs tances .  
and mass s p e c t r a l  d a t a  on the  a n a l y s i s  of a sample con- 
s i s t i n g  of a c e t o n i t r i l e ,  furan  and py r ro l e  are presented.  
O t h e r  samples of aromatic hydrocarbons, p a r a f f i n s  and 
organic  compounds of  b i o l o g i c a l  s i g n i f i c a n c e  were also 
analyzed. 
samples of a f e w  micrograms w e r e  ob ta ined  wi thout  the use 
of molecular s epa ra to r s .  
which w e r e  equ iva len t  b u t  n o t  i d e n t i c a l  t o  t h a t  obtained 
from an LKB 9000 instrument  which w a s  used as a s tandard  
Chromatographic 
Mass s p e c t r a  of i n d i v i d u a l  components i n  
The new apparatus  y i e lded  r e s u l t s  
f o r  comparison. 
below.150 are reliable and promising r e s u l t s  were also 
obta ined  with compounds of mass up t o  500. 
The d a t a  obta ined  w i t h  compounds of mass 
INTRODUCTION 
The usefu lness  of  s o p h i s t i c a t e d  a n a l y t i c a l  gas  chromato- 
graph-mass spectrometer  combinations c u r r e n t l y  i n  use has  
been w e l l  e s t ab l i shed .  
and mass spectrometry o f f e r s  a l l  the advantages i n h e r e n t  i n  
e i ther  of these techniques wi th  a d d i t i o n a l  r e s u l t i n g  advan- 
t ages  i n  the combination. These have been described and 
d iscussed  i n  some de ta i l  mainly by Ryhage'l) Watson and 
( 2 )  Lipsky et;. a l .  Biemann 
"he i n t e g r a t i o n  of gas  chromatography 
( 3 )  a n i  O r o '  et. al .  ( 4 )  - -
. .  
-2- 
b 
The present study demonstrates the analytical poten- 
c 
tial of an integrated instrument made of a standard general 
purpose gas chromatograph and a compact relatively simple 
low cost quadrupole mass analyzer. 
EXPERIMENTAL 
The experimental work consisted of building and testing 
a gas chromatograph-mass spectrometer combination of stan- 
dard, but otherwise unrelated, sub-systems. A block dia- 
gram of this system is shown in Figure l. 
The gas chromatograph was a temperature programmed 
Barber-Colman system equipped with a stainless steel capil- 
lary column (1500 centimeters x 0.076 centimeters inside 
diameter) coated with 10 percent SF-96. The desired 
chromatographic separation was achieved through the proper 
choice of temperature and flow conditions. A stream splitter 
was constructed to direct approximately 80 percent of the 
effluent into the hydrogen flame detector and the remainder 
to the variable leak valve on the vacuum chamber. The 
connection between the chromatograph column splitter and the 
vacuum chamber was accomplished through the use of a stain- 
less steel capillary (90 centimeters x 0.05 centimeters 
inside diameter) directed to the sapphire disc of the Varian 
bakeable variable leak valve. Adjustments of this valve 
permitted any choice of sample load to the mass spectrometer 
commensurate with the capabilities of the ion detector and 
-3- 
b 
pumping system. A standard (60  centimeters x 30 centimeters 
inside diameter) bench top bell jar vacuum system was equipped 
with a 50 liter per second cold cathode sputter ion pump and 
a 4,000 liter per second hot filament titanium sublimation pump. 
Vacuum pressure measurements were made with the ion pump current. 
Within the vacuum system the sample was conveyed to the ionizer 
6' 
of the mass spectrometer through a pyrex tube (50 centimeters x 
0.6 centimeters inside diameter), which was heated by vacuum- 
compatible General Electric Type T-3 quartz infrared heaters. A 
standard Ultek-EA1 Quadrupole Model 250 Residual Gas Analyzer 
(Figure 2) was connected to the bell jar and served as an "analyti- 
cal" mass spectrometer. Mass spectra achieved from this device 
were displayed on a Minneapolis-Honeywell 1508 Visicorder system. 
The analytical procedure consisted of injecting 0.5 microliter 
of sample into the gas chromatograph under conditions of temperature 
and hydrogen carrier flow rates to produce peaks of approximately 
30 seconds duration. The variable leak valve was adjusted to 
cause the pressure within the vacuum chamber to be less than 
5 x torr, but large enough to provide adequate sensitivity. 
Gas chromatograms and mass spectra were produced by the flame 
ionization detector and the quadrupole mass spectrometer, respec- 
tively. When the sample peak was registered on the strip chart 
recorder, Amass spectrjt was displayed on the Visicorder by 
actuating the chart drive and sweep scan simultaneously. The 
peaks were scanned at a rate of approximately 4 seconds per 100 
P4 k& corrQs pon dins 
atomic mass units. The ion source conditions of the quadrupole- 
mass filter were established in keeping with the normal proce- 
dures set up as if using the instrument as a residual gas analyzer. 
0. 
-4- 
A tungs ten  f i l amen t  w a s  used t o  e m i t  70 e l e c t r o n  vo l t  
e l e c t r o n s  i n  t h e  ion  source.  
RESULTS AND DISCUSSION 
Typical  r e s u l t s  obtained wi th  t h i s  system are i l l u s t r a -  
t ed  i n  Figures  3 and 4 .  Figure 3 is a gas  chromatogram of 
a sample made up of equal  mole f r a c t i o n s  of a c e t o n i t r i l e ,  
fu ran  and py r ro l e .  Figure 4 is  the m a s s  s p e c t r a  of t h e s e  
three compounds obta ined  a s  each one emerged from the gas 
chromatograph. 
The  instrument  w a s  also app l i ed  t o  t h e  a n a l y s i s  of 
mixtures of C -C 
hydrocarbons. Perfluorokerosene and per f luoro t r ibu ty lamine  
w e r e  used f o r  c a l i b r a t i o n  purposes up t o  approximately 500 
atomic mass u n i t s .  
normal p a r a f f i n s  and C6-C9 aromatic 6 1 0  
Practical  s e n s i t i v i t i e s  and adequate s i g n a l  t o  no i se  
r a t i o s  w e r e  achieved wi th  sample s i z e s  of 0 .05  microliter 
and less. 
.or slower g ive  rise t o  w e l l  r eso lved  m a s s  s p e c t r a .  Further-  
more t h e  d a t a  obta ined  w i t h  t he  i n t e g r a t e d  system i n d i c a t e s  
t h a t  t h e  du ra t ion  of the .gas chromatographic peak should 
b e  approximately 1 0  t i m e s  t h e  mass scan  t i m e .  
Scan speeds 5 mi l l i seconds  pe r  atomic mass unit, 
? 
t 
-5- 
When using t i t an ium subl imat ion pumping, and hydrogen 
carrier gas ,  a variable leak valve may be  used t o  admit 
samples d i r e c t l y  i n t o  t h e  mass spectrometer  ion  source.  
Because of the high pumping ra te  f o r  hydrogen and t h e  wide 
dynamic range of this quadrupole mass ana lyzer ,  no means of 
gas en r i ch ing  or  molecu la r  s e p a r a t i o n  is  necessary.  
t i m e s  of t h e  i n t e g r a t e d  system w e r e  such t h a t  no measurable 
Response 
peak broadening was produced by the mass analyzer .  
ope ra t ing  t h e  m a s s  spectrometer  a t  a r e s o l u t i o n  of approxi- 
When 
mately one p a r t  i n  200,  e x c e l l e n t  data w e r e  obtained with 
samples up t o  150 atomic mass u n i t s .  It i s  expected t h a t  
the performance of t h i s  device can be r a i s e d  t o  permit  t h e  
L 
X 
a n a l y s i s  of samples of molecular weight approaching 500 
atomic mass u n i t s .  A t  p r e s e n t ,  however, m a s s  discrimi- . 
n a t i o n  seems t o  l i m i t  the mass range. Mass s p e c t r a  of 
c e r t a i n  b io rgan ic  substances produced by the  quadrupole mass 
spectrometer  are i n  genera l  comparable, b u t  n o t  i d e n t i c a l ,  
t o  those  obtained from t h e  convent ional  l abora to ry  a n a l y t i c a l  ' 
m a s s  spectrometer  system. 
Curren t  s t u d i e s  are being concentrated on t h e  a n a l y t i c a l  
de te rmina t ion  of a )  hydrocarbons and other molecules of 
presumed b i o l o g i c a l  o r ig in ,  e.g. phytane, p r i s t a n e  and 
farneeaner b) organic compounds reou l t ing  from the thermal 
outgass ing  of terrestrial  and extraterrestrial  samples; C )  
pyro lyza tes  of b a c t e r i a  and other micro-organisms. 
-6- 
In summary, this work demonstrates that it is feasible 
to build a simple instrument for the mass spectrometric 
analysis of gas chromatographic effluents. It is hoped 
that continuation of this work will lead to the development 
of space flight instrumentation for the analysis of organic 
compounds, on planetary surfaces (4) 
. ACKNOWLEDGEMENTS 
We thank J. Miller, R. Wilkin, and R. Mathews for help 
in various phases of this work. 
in part by grants, NGR-44-005-043 and NGR-44-005-020, from 
the National Aeronautics and Space Administration. 
These studies were supported 
LITERATURE CITED 
1. Ryhage, R. Anal. Chem. 36, 759 (1964). 
2. Watson, J. T., and Biemann, K. Anal.Chem. -- 36, 1135 (1964). 
3.  Lipsky, S. R., Horvath, C. G. and McMurray, W. J. Anal. -
Chem. 38, 1585 (1966). 
--
e 
- -  
4 .  Oro', J., Biemann, K.t Gohlke, R.S., Lipsky, S.R., Love- 
lock, J.E., McLafferty, F.W., Meinschein, W. G., and 
Ryhage, R. _. in chapter "Analytical Me'thods for Landers", 
Rea, D.G. ed., in "Biology and the Exploration of Mars", 
Pittendrigh, C.S., Vishniac, W., and Pearman, J.P.T., eds., 
pp. 378-384, National Academy of Sciences National Research 
Council, Washington, D . C . ,  1966. 
t 
Figure 1 
Block diagram of the gas ckromatograph- 
quadrupole mass spectrometer system. 
I 
BLOCK DIAGRAM - *  . 
GX./ QUADRUPOLE M.S. 
G A S  
C HROMATO GRAPH 
HYDROGEN -FLAME 
D ETLCTO R 
L E A H  VALVE 
VACUUM SYSTEM 
QUADRUPOLE 
MASS FILTER 
R ECOR DI  N G 
OSC I L L o G R A P )-I 
(M.S. DATA) 
( 
8 
Figure 2 
Schematic diagram of the quadrupole 
mass analyzer. 
,. . 
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zi ? 
., 
a .  
. I  
4 
Figure 3 
c 
Gas chromatogram of a mixture of 
.acetonitrile, furan and pyrrole. 
Column: 150 m x 0.76 mm inside 
diameter. Substrate: 10% SF-96 , 
(100). Temperature: 25OC. 
Pressure: 10 psi H2. 
a 
. I\ 
4 
? 
z 
I 
2 
L 
c 
Figure 4 
Mass spectra of the  compounds separated 
by gas chromatography (Figure 3 )  obtained 
with the quadrupole mass spectrometer. 
Total pressure 2 x torr; tungsten 
f i lament,  70 e V  e l ec trons .  
R L 1 Arl VC 
INTENSITY 
40 14 
29 
26 
12 
I8 
I 
41 
. 
.- 
i 20 
29 
1 I l l 1  , '*,to I a .  I II I I I i I1 
I-
I IO 20 30 40 50 60 70 
MASS IN A.M.U. 
. I  
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I 14 
ACETONITRILE CHJN 
I 1 1 1 1  ! I 1 1 1 1  I II I I I I 
M A S S  IN A.M.U. 


Gas Chromatograph-quadrupole Mass Spectrometric Analysis of Organic Compounds

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