An injection system for a gas chromatograph is described which uses a small injector chamber (available in various configurations). The sample is placed in the chamber while the chamber is not under pressure and is not heated, and there is no chance of leakage caused by either pressure or heat. It is injected into the apparatus by changing the position of a valve and heating the chamber, and is volatilized and swept by a carrier gas into the analysis apparatus

Donaldson, R. W., Jr.

Henderson, M. E.

Pollock, G. E.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMINISTRA
WASHINGTON, D.C. 20546
JUN 23
REPLY TO
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Attn: Miss Winnie M. Morgan
GP/Office of Assistant General
Counsel for Patent Matters
SUBJECT: Announcement of NASA-Owned U.S. Patents in STAR
inj In accordance with the procedures agreed upon by Code GP
xJ and Code KSI, the attached NASA-owned U.S. Patent is being
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The following information is provided:
U.S. Patent No. : 3, ? *$ 'i ^ W-5
Government or : V/ - o-. ^ > o 0 ^  \~ /\ i/r\e^ \^ ~
Corporate Employee .
Supplementary Corporate : . '
Source (if applicable)
NASA Patent Case No. : 7%? C~ /^ 3 V/-^
NOTE - If this patent covers an invention made by a corporate
employee of a NASA Contractor, the following is applicable:
YES A-/ NO /£C7
Pursuant to Section 305 (a) of the National Aeronautics and
Space Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
inventor (author) appears at the heading of column No. 1 of
•the Specification, following the words "...with respect to
Van invention of ..."
Bonnie L. Woerner
Enclosure
https://ntrs.nasa.gov/search.jsp?R=19750018262 2020-03-19T21:03:48+00:00Z
United States Patent
Pollock et al.
[in 3,887,345
[45] June 3, 1975
[54] GAS CHROMATOGRAPH INJECTION
SYSTEM
[15] inventors: Glenn E. PoUock, Be\monV; Milton
E. Henderson, Mountain View;
Ralph W. Donaldson, Jr.,
Sunnyvale, all of Calif.
[73] Assignee: The United States of America as
represented by the United States
National Aeronautics and Space
Administration, Washington, D.C.
[22] Filed: Feb. 27, 1974
[21] Appl. No.: 446,564
Related U.S. Application Data
[63] Continuation of Ser. No. 180,962, Sept. 16, 1971,
abandoned.
[52] U.S. Cl 55/386
[51 ] Int. Cl BOld 15/08
[58] Field of Search 55/67, 197, 386
[56] References Cited
UNITED STATES PATENTS
3,365,951 1/1968 Jenttsch 55/197 X
3,408,793 11/1968 Frazer 55/197
3,475,964 11/1969 Jenkins 55/197 X
3,511,029 5/1970 Azarraga et al 55/67
3,626,761 12/1971 Haruki et al 55/197 X
Primary Examiner—John Adee
Attorney, Agent, or Firm—Darrell G. Brekke; Armand
G. Morin, Sr.; John R. Manning
[57] ABSTRACT
An injection system for a gas chromatograph is pro-
vided wherein the sample to be introduced is placed in
a chamber which may be cool and not under pressure
and is then injected into the apparatus by changing the
position of a valve and heating the chamber whereby
the sample is volatilized and swept by a carrier gas
into the analysis apparatus.
6 Claims, 6 Drawing Figures
CARRIER
GAS
c r
COLUMN
I HEATED ZONE
I I
PATENTED JUN 3 1975
"3 P p V ~ A
•~J , O U I , O —T
CARRIER
GAS
HEATED ZONE I
I I
CARRIER
GAS
A
FI
1
 HEATED
I I
GL£A/W £.
_, MILTON E. HENDERSON
mm IV. DONALD SON JR.
INVENTORS
£*tX-K, Si.
ATTORNEY
PATENTED JOH 3 1975 3.887.345
CARRIER
6/15
CARRIER
GAS
c r
COLUMN
MILTON E.
1?/ILP// IV. DONALDSON, JR.
INVENTORS
«^^e J.
ATTORNEY
PATENTEDJUN3 1975
cure J
3.887,345
CARRIER
S?1\
57 un,^ ZflA/Ej
RESTRICTOR
£.
£. WfAIOf^SOAl
JNATNTORS
BY
1
3,887,345
GAS CHROMATOGRAPH INJECTION SYSTEM
The invention described herein was made by employ-
,ees of the United States Government and may be man-
ufactured and used by or for the government for gov-
ernmental purposes without the payment of any royal- 5
ties thereon or therefor. .
CROSS REFERENCES TO RELATED
APPLICATIONS
Tu. . . . r' i- • c HI l o r v n ^ T ,,>This is a continuation of application Ser. No. 180.962 10
c, ,
 c , ., .„-.. u i jfiled Sept. 16, 1971 , now abandoned.
BACKGROUND OF THE INVENTION
1 Field of the Invention
Gas chromatograph. 15
2. Description of the Prior Art
Gas chromatographs are well known for use in ana-
lyzing materials and are particularly valuable for ana-
lyzing materials when only very smail samples are avail-
able. In the past, samples have ordinarily been mtro- 20
duced into such chromatographs by dissolving the sam-
ple in a suitable solvent and then utilizing a syringe nee-
die of slender dimensions to puncture a septum of some
pliable organic polymer. The needle, after puncturing
the septum, is exposed to a hot zone under pressure. 25
The plunger of the syringe is then pushed in, injecting
the sample into the hot zone. The liquid is vaporized
and a carrier gas, which is continually flowing in the di-
rection of the column, sweeps the vaporized gases into
the chromatographic column. 30
Such conventional injection systems have a number
of disadvantages. These can be enumerated as follows:
A. The syringes which are used in such systems have
i i.- t. • • ui u -.u .•a plunger which invariably becomes worn with time as
the result of friction and/or the use of samples which 35
tend to erode or corrode the plunger or barrel. When
the parts become worn, the vaporized sample may es-
cape out the plunger barrel, causing lower accuracy
and reproducibility.
B. The sample is injected into a heated injector block 40
which causes a pressure in all directions as soon as the
neddle is inserted through the septum. A part of the
sample can be lost if the syringe is worn in the least.
C. The losses of the syringe barrel are increased by
injecting into a heated zone which has a high carrier gas
pressure. As soon as the syringe is inserted in the ori-
fice, the material in the syringe is subjected to the car-
rier gas pressure which can press the liquid or gas out
through the plunger barrel. The high temperature of
 5y
the usual injection block further increases this ten-
dency. When the operator overcomes this pressure by
pushing the plunger, the sample may be lost if the
plunger is worn.
D Another disadvantage is that most pnor systems
 55
employ some form of a septum which is usually an or-
. . ..., , ,- . .game polymer. These polymers wear out after repeated
punctures, so that the life of the septum is relatively
short. Further, since the polvmer is heated to a rela-
lively high temperature, it mav be degraded by the high
temperature and may bleed 'out compounds such as 6°
plasticizers which are used in the manufacture of the
material. Such material may be swept through the gas
chromatograph column, causing possible errors, both
of a quantitative and qualitative nature.
 65
E. Another disadvantage of the prior art system is
that the injected solvent may obscure some sample
peaks if the solvent volume is large. Further, when
large quantities of solvent are used there is a tendency
to disturb the liquid phase of the column. Naturally
these effects grow greater as the quantity becomes
greater.
p. Another disadvantage is that the sample may exist
in a very di|ute soiution which requires the operator to
either use a large volume of solvent for injection or to
concentrate the sample prior to heating. Since very
small volumes must be handled, a high volumetric error
, , ., , ...
may be made even under ideal conditions./ ~ A I U I . • • , _
 L j - jG. Although some injectors have been designed
which do not use the septum, they all require a valve
of some type and ordinarily the valve is one utilizing ex-
otic
 materials and frequently is very difficult to con-
struct. The valves are ordinarily heated and upon being
degraded, give rise to many of the difficulties outlined
above in conjunction with the system of using a septum.
SUMMARY OF THE INVENTION
The present invention employs a small injector cham-
ber which can be made in various configurations in
which the sample is placed. The sample is placed in the
chamber while the chamber while the chamber is not
under pressure and is not heated. Thus, there is no
chance of leakage caused by either pressure or heat.
Even if a syringe is used to inject the sample into the
sample chamber, it lasts almost indefinitely since it is
not exposed to a high temperature or pressure during
^ ^
 addiUonAnQther adva of the nt invention is that
thefe need be no Q as a $ ^ ^, ,.,,,_ . . .
 r
. . .
 r
 ,. ,ne
 difficulties associated with septums, outlined
, ,-. .
above, cease to exist Further there are no O-nngs or
g|ands whlch m'Sht leak or bleed- Causin8 erroneous
results.
The onl>' moving part in the whole system is a single
valve of the two position rotary type and this valve is
not subjected to heat or to the sample. The valve is not
critical and even should it leak somewhat, it will not
contribute to inaccurate results.
In accordance with the present invention very dilute
samples can be analyzed by placing a large volume of
solvent with the sample in the sample chamber, evapo-
rating the solvent from the sample with carrier gas in
reverse flow mode, at the same time depositing the
sample on the injector's inner surface. The injector can
then be posj,jveiy c|osed and the sample flash heated
and the carrier gas turned on to the inject mode to
sweep the vaporized sam te into the co|umn.
yhe system Qf the presem inventjon a,so ,ends itself
to a t varjation in vo|ume. Thus, for example, the
vo,ume . ^ cm bg extreme, smal, and the deadJ
 . ' . . .
volume very low so it has the potential of giving betterr
 D C ,
' . . . . .
a
 Th
K
e device of
 <he Pr«ent invention also has great
flexibility, since ,f one desires to use the septum, the
opening to the injector can be provided with a septum
and the samPle inserted into the inJector through the
septum while the injector pot is hot or cold, with or
without the carrier gas flowing. Thus, the present sys-
tern is completely flexible.
The device of the present invention lends itself to
manual and automatice operation and/or remote con-
trol.
3,887,345
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of an injector embodying the
present invention.
FIG. 2 shows the structure of FIG. 1 with a sample
being injected into the chromatographic column.
FIG. 3 shows another embodiment of the invention
wherein a cylindrical chamber is used for injection.
FIG. 4 shows the structure of FIG. 3, while a sample
is being injected into the chromatograph column.
FIG. 5 shows another embodiment of the invention
wherein a flat or rectangular injection chamber is em-
ployed.
FIG. 6 shows the structure of FIG. 5 while a sample
is being injected.
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
Although this is a preferred method of operation, it
is not necessary to drive off the solvent in a separate
step. If desired, line 15 can be closed as soon as thq .
sample is in injector 7 and all the material in the cham-
5 ber 7 passed through the chromatograph.
In FIGS. 3 and 4, a somewhat similar system is used
except for the configuration of the injector chamber
and the configuration of the piping leading to and from
the chamber. Here the chamber 43 is in the form of a
10 cylinder having a conical bottom and has a baffle 45 at
approximately the center thereof. A direct gas inlet 47
provided from the valve 25 and a sample inlet tube 49,
both on one side of the baffle 45. On the opposite side
• of the baffle 45 is placed an inlet tube 51 for carrier gas
15 and an outlet tube 53, leading to the gas chromato-
graph 39. It will be seen that the tee connection previ-
ously used is no longer employed and the gas from the
restrictor flows directly into the chamber 43. However,
the method of operation is the same as previously de-Referring to the drawings by reference characters
there is shown in FIG. 1 an embodiment of the inven- 20 scribed. First the sample is loaded into the chamber 43
tion wherein an injection chamber 7 is employed, hav- then gas is admitted by valve 25 through the restrictor
25
30
ing a flat top 9 and a hemispherical bottom 11. The size
of chamber 7 can vary from a few microliters to a few
hundred microliters. Chamber 7 is provided with three
openings namely, 13, 15, and 17. It will be noted that
the opening 13 has a tube 19 which enters the chamber
and is directed downwardly to prevent a direct passage
of gas from the tube 13 to the opening 17. The struc-
ture thus far described is placed in some form of zone
generally designated 21 so that it can be flash heated.
Direct resistance heating of the injector 7, radiant heat-
ing and hot air heating are all suitable. A source (not
illustrated) of a suitable carrier gas is provided such as
helium, hydrogen, nitrogen, or argon and this enters
the system through line 23. Line 23 leads to a two-way 35
valve 25 having outlet ports 27 and 29. Port 29 leads
to line 13 while port 27 leads through a restrictor 31
and then through line 33 to a tee connection 35, one
leg of the tee leading to line 17 and the injection cham-
ber and the other leg of the tee leading through line 37
to the gas chromatograph column 39.
In operation, the sample would first be placed in the
chamber 7 through opening 15. At the time the sample
is placed in the chamber 7, it is unheated and under no
pressure from the carrier gas. After the sample is
placed in the injection chamber 7, valve 25 is opened
so that the gas from line 23 flows only through line 27.
The gas passing through the chamber through line 17
will sweep the solvent out through line 15. After the
solvent has been evaporated, line 15 is closed in any
suitable manner such as by the cap 41. At the same
time valve 25 is turned so that carrier gas can flow out
through both ports 27 and 29 and zone 21 is flash
heated. Thus, the gas flows through line 13 over the
sample in the chamber 7 and, sweeps the sample
through line 17 and line 37 into the chromatograph 39
for analysis. A small portion of the gas from line 23 will
pass through restrictor 31 through the tee joint 35 and
into the column 39. It will be seen from this description
that the sample is placed in the chamber at the time the
chamber is cold and not under pressure so that the
usual difficulties with the septum are avoided. The
chamber itself can be used for the evaporation of the
solvent so that the solvent for the sample need not pass
through the chromatograph, avoiding the errors which
frequently result from the presence of too much solvent
in the chromatograph.
40
45
50
55
60
31 and the opening 51. The solvent is driven out
through tube 49. When the solvent has been driven out,
the tube 49 is closed as by the cap 55 and the valve 25
turned so the gas can flow through line 47 as well as
through restrictor 31, the injector being flash heated to
volatilize the sample and the gas sweeping the sample
through line 53 into the chromatograph 39.
We claim:
1. An injection system for a gas chromatographic col-
umn comprising in combination:
a. an injection chamber for receiving a sample to be
analyzed;
b. valve means for controlling the flow of carrier gas;
c. said chamber having three conduits leading into
said chamber, a first conduit for inserting a sample
into said chamber and for venting gas and solvent,
a second conduit connected through a restrictor to
said valve means and to said chamber for injecting
carrier gas into said chamber, and a third conduit
connected to said valve means and said chromato-
graphic column for injecting gas into said chamber
and for sweeping a vaporized sample into said
chromatographic column;
d. means for closing said 1st conduit; and
e. flash heating means for heating said chamber and
for vaporizing said sample.
2. The structure of claim 1 including a baffle extend-
ing downwardly into said injection chamber and sepa-
rating said first and second conduits from said third
conduit for preventing direct flow of gas and vapor be-
tween said first and second conduits and said third con-
duit and vice versa.
3. The structure of claim 1 wherein said injection
chamber is in the form of a hen-.isphere having a
rounded bottom and a flat top.
4. The structure of claim 1 wherein said injection
chamber is in the form of a cylinder having a conical
bottom.
5. An injection system for a gas chromatographic col-
umn comprising in combination:
a. an injection chamber for receiving a sample to be
analyzed;
b. valve means controlling the flow of carrier gas to
said chamber;
c. said chamber having four conduits leading into
said chamber, a first conduit for inserting a sample
3,887,345
into said chamber and for venting gas and solvent,
a second conduit connected to said valve means
and*said chamber for injecting carrier gas into said
chamber, a third conduit connected through a re-
strictor to said valve means and to said chamber for
injecting carrier gas into said chamber and for
sweeping a vaporized sample into said column, and
a fourth conduit connected to said chamber and
said column for carrying vaporized sample and gas
into said chromatographic column;
d. means for closing said first conduit; and
10
e. flash heating means for heating said chamber and
for vaporizing said sample.
6. The structure of claim 5 wherein the injection
chamber is in the form of a rectangular member having
a V-shaped baffle extending downwardly from the top
of said chamber separating said first and second con-
duits from said third and fourth conduits for preventing
direct flow of gas and vapor between said first and sec-
ond conduits and said third and fourth conduits.
15
20
25
30
35
40
45
50
55
60
65


Gas chromatograph injection system

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