Note: Descriptions are shown in the official language in which they were submitted.
W09~/09572 PC~/US90/00584
- BREATH SAMPLER
-
Field of the Invention
The presen~ invention relates to methods and
de~ices for measuring and analyzing contents of gas
samples, and more particularly to a method and apparatus
for sampling volumetric quantities of human exhaled
breath, and then either performing on-site analyses for
measuring volatile compounds present in the sampled
volume of breath, or stori~g the sampled ~olume so that
appropriate analyses can be performed at a later time.
BACKGROUND OF ~HE INVENTION
For nearly two decades, there has been a grow-
ing need for gas sampling devices capable of applications
beyond the more typical uses, as ~or example achieving
law enforcement objectives (e.g., breathalyzers~ and
achieving medical objectives (e.g., patient breathing
assist). Indeed, since 1970 when OSH~ was established,
there has been an .increased awareness of the need to
continuously monitor conditions in the workplace to
assure compliance with Federal and State regulations.
Since breath is the only ~iological fluid that
may be obtained non-invasively and on demand, it is
currently the matrix of choice for a number of applica-
tions as for example in law enforcement and medical
evaluation such as breathalyzers and patient breathing
assist. These uses generally rely on the fact that the
concentration of the analyte of interest is in very high
concentrations such as ethanol or carbon dioxide and can
be analyzed with instrumentation that does not require
separation of the analyte from other interferents.
~ .tial attempts at collecting exhaled breath
samples for analyses of volatile substance content in-
volved the use of two types of app~ratus, namely the
glass sample tube and the gas sampling bag. The glass
sample tube permitted only a limited sample volume to be
collected, and its use was short-lived. On the other
hand, the gas sampling bag enjoyed a far longer useful-
ness for this purpose. Nevertheless, this apparatus has
- - - . : . . . .
- , . ; ~ ... .. , . i I . .
" . . . . , , . . ~ , . :. , ~ .:
,: ,: : , .. , ~, . . .
:` -:: ', : , , ,i , , , , ""
WO9Q/09572 PCT/~90/00584
~? ~ ~3~3~ ~ - 2 ~
- its shortcomings as well, and for those reasons its use
also is inherently limited. Nost significant among the
ob jections is that in most circumstances the bag becomes
bulky after sample collection and must be almost immedi- r~
ately transfexred to a laborato~y in order ~hat desired
analyses can be performed,
Furthermore when using such gas collection
containers, concentration of a gas component using an
absorbent is generally not feasible and therefore measur-
ing an analyte in large volumes of exhaled breath thatare contributed over a long period of time is not practi-
cal.
For the purposes of this art, two different
breath samples can be taken, namely a "mixed" and an
nend" or alveolar breath sample. A solvent in the deep
lung or alveolar region of the lung is in intimate con-
tact with solvent in the bloodstream. If a sample of
solvent in the deep lung air is obtained that sample will
be referred to as an alveolar or end-expired sample. As
the solvent is exhaled, the sample becomes diluted with
air in the upper respiratory track and is known as a
mixed expixed sample. Generally an alveolar sample is
regarded as being indicati~e of bloodstream solvent con~
centrations since that sample is in intimate contact with
solvent in the blood stream. The manual technique for
end-expired sampling requires the subject to hold his
breath for about 20 seconds then to exhale, discarding
the first 30-50% of the sample; and finally collecting
the end-exp~red portion of the sample with the sampling
device. There are also automated techniques for sampling
end~expired air.
The concentrations of solvents in an exhaled
breath sample are normally very low. Therefore, it has
been found necessary to have the analytes in the bag
sufficiently concentrated on an appropriate sorbent prior
to analysis. In addition, if the analytes are stored in
the bag for extended periods, severe losses of analyte
. .
W090/09~72 2 ~ 5 PCI /USgO/00584
' - 3 -
may occur by absorption of the analyte into the bag wall
or permeation of the analyte through the ~ag wall. In
using the gas sampling bag, it has become apparen~ that
concentrations of the analytes on solid sorbent material
is generally not feasible in the field. The only tech~
nique for concentrating the contents of the bag is via
indirect means. The sample must first be trapped in the
bag. A solid sorbent sampler is then connected at one
end to the bag and the other end to a pump. A known
volume of air in the bag is then sampled. Thus, outside
of the laboratory, neither the gas sampling bag nor the
glass sample tube has been found to facilitate either
direct concentration of volatile analytes in the samples
taken or storage of the taken samples for extended
periods of time.
Subsequently, other devices have been developed
or sampling volumes of exhaled breath. For example,
U.S. Patent No. 4,046,014 to Boehring~r et al discloses a
charcoal tube sample device for sampling respiratory
gases in alveolar air. Another sampling device, which
employs changes in pressure or flow rat~ in a main gas
flow tube to initiate the sampling process as well as to
terminate it, is disclosed in U.S. Patent No. 4,297,871.
Still another gas sampling device, disclosed in U.S.
Patent No. 3,858,593 to Ryan et al, incorporates a
cylindrical alveolar gas trapping device having check
valves at opposite ends which are openable upon applica-
tion of exhalation pressure, and a side wall valved
access tubs for selective removal of the trapped gas from
within the cylinder ~o a gas analyzer. Each of these
subsequently developed devices also suffer disadvantages
which make them undesirable for use. In particular,
there is no provision for continuous mixed-expired
sampling or filtering of inhalation air~ and no provision
for storing the collected gas sample for analysis at a
su~sequent time.
.. .
, ~ , . ,~, ~ . -
WO90/09572 PC~/US9~/00~84
- 4 - ;
Obiects of the Invention
It is ~herefoxe an object of the invention to
overcome deficiencies in the prior art, such as indicated
above.
5It is a further object of the present in~ention
to provide impro~ements in analysis and in gaseous
sampling.
It is another object of the present invention
to provide a breath sampling device capable of sampling
trace amounts of compounds in large volumes of human
breath for analysis by conventional gas analyzer
apparatus or other analytical procedures to determine the
presence of trace levels of volatile compounds.
It is still another object of the invention to
sample ~race analytes using a layered sorbent sampling
scheme. For example, high molecular weight analytes are
collected on the first layer of the sampling stack using
a carbon-type sorbent. Low-molecular weight compounds
pass through the first stage and are collected on the
second or tertiary stage using a sorbent such as
molecular sieves.
It is still another object of this invention
that the sidestream port may be used ~or purposes other
than sampling. For example, in order to count the numbex
of breaths, the port may be connected to a pressure
sensor that converts positive or negative pressure
impulses into a signal that is registered by a counter.
It is still another object of the invention to
provide a mainstream- or sidestream sample canister that
can be desc~bed by solvents or thermal desorption tech-
niques or by supercritical fluid extraction.
Yet another object of the invention is to pro-
vide a breath sampling device capable of collecting main-
stream samples or sidestream samples using sorbents.
Suitable activated charcoal-based sorbents include any
activated natural charcoal as well as synthetic char-
coals. An example of a natural charcoal is coconut-based
: . -: .:, . . ~.: : - ................... : :.. .
:. . . . . . .
,: . , , ~ .
WO 90/09572 ~ PCI/1,'590/00;84
.. ` _ 5 --
charcoal. ~xamples of synthetic charcoals include
activated charcoal cloth, activated petroleum or coal
based charcoals, and other activated carbons which are
commercially available such as Carbotrap~, Carbosieve~,
and Car~opack~. Suitable inorganic sorbents include the
molecular sieves (synthetic or natural zeolites), silica
gel and diatomaceous earth sorbents. Suitable synthetic
resin soxbents include porous polymers such as Tenax~,
XAD-2~, the Porapak~ series polymers (e.g. Porapak S),
and the Chromosorb~ series polymers te.g. Chromosorb
101 ) .
Another possible collection technique for both
mainstream and sidestream sampling is to use a reagent-
coated sorbent where the reagent reacts with the exhaled
analyte to form a stable derivative. For example low-
molecular weight aldehydes can be sorbed by contact with
2-(hydroxymethyl)piperidine-coated XAD-2. The unstable
aldehydes are converted to oxazolidine derivatives which
are ~table and can be stored for later analysis.
Yet another object of the invention is to pro-
vide a breath sampling device capable of sidestream moni-
toring of the breath concentrations using suitable
detection means such as a mass-spectrometer ~or breath-
by-breath measurements of the relevant analytes. No
technique other than a face mask previously permitted
such monitoring in a contaminated environment.
Yet another object of the invention is to
obtain a multi-breath sample. In this case the exhaled
breaths ar~ all passed through the same adsorbent bed so
that the ~r~alyte from all the breaths are sorbed. This
permits the measurement of very dilute concentrations of
analyte which are sorbed from large volumes of breath
over extended sampling periods.
Still another object is to provide a breath
s~mpling device having alternative configurations which
permit the collection of sidestream or mainstream
samples, which facilitate purification of inhaled air or
: :: . : : - .: ~ ' ' :
. , '' '' , ,- , ~. .: :
WO90/09572 PCT/US90/0058~
- 5 _ ~.
use a pre etermined breathing gas source such as pressur-
ized air, and which enable collection of the samples
without use of a facemask.
~et a fuxther object is to provide a breath
sampling device having almost no plas~ic csmponents,
o~her than a mou~hpiece and an inlet check valve dia-
phragm, with which the breath sample comes. in contact.
However, the sampler could be made from PTFE (Teflon~) or
any plastic which has minimal capacity to absorb
solvents.
Still a further object of the invention is to
provide a unified sampler which can be used for both
mixed and alveolar breath sampling.
It is still another object of the present
invention to provide a system whereby collected samples
of breath analytes can be analyzed at any convenient .
time, for example immediately on-site or after shipment
of sorbent canisters to a laboratory having sophisticated
equipment.
Yet another object is to provide a breath
sampling device capable of being heated so that condensa-
tion of water vapor and analyte are prevented.
Yet another embodiment of the invention i5 to
test a subject in the.presence of contaminated air by not
filtering the inhaled air. By measuring the amount
exhaled, one can determine the amount or percent a~sorbed
by the subject and thereby determine the dose received.
The invention is applicable to a number of
situations -where monitoring one's breath may be desirable
in accordance with the invention. These include:
a. Control of substance abuse by determination
of the concentration of volatile solvents or other mater-
ials that are present in the breath such as alcohol or
toluene from inhalation of paint thinner vapors or glue
sniffing.
b. Measurement of volatile compounds such as
oral antiseptics in support of advertising efficacy
,
, "
,. . .
. .
WogO/09572 PC~/~S90/005~
:: 2 ~
claims by cosmetic manufacturers. Similarly, volatile
compounds in the breath that are present from smokins,
such as nicotine, may be measured for smoking-cessation
or for other research purposes.
c. Measurement of trace levels of endogenous
compounds in the breath that may be markers of a disease
state such as breath acetone in diabetes.
d. Measurement of volatile endogenously-
produced or used compounds such as carbon dioxide, oxygen
or various other metabolites~
e. Monitoring workers or residents in the
vicinity of hazardous areas, especially wastesites, for
uptake of toxic chemicals.
f. Estimation of blood concentrations of
absorbed organic solvents and of the volatile metabolites
of these compounds that are excreted in the breath.
g. ~easurement of natural air gasses which are
not metaboli~ally used or produced such as nitrogen to
provide internal controls and comparisons.
h. Support of breath-based biological exposure
indices (BEI,s) for control of worker exposur~ to
hazardous compounds, especially solvents. The BEI's
establish maximum concentrations for hazardous compounds
in the various biological fluids. As such, this approach
is superior to environmental monitoring of wor~er ~reath-
ing zones to assure compliance with current State and
Federally~mandated concentration standards. Breath based
BEI's have been promulgated ~y the American Conference of
Governmenta:l Industrîal Hygienists since 1981, and recog-
nize that adsorption of hazardous chemicals by workers is
quite variable due to dermal exposure and to ergonomic
differences that affect individual ventilation rates.
The breath-based BEI's to be supported by this invention
may rely on either or both mixed and alveolar sampling.
The Federal Republic of Germany currently has standards
for maximal levels of chemicals in the breath of exposed
workers.
... - .,, ~ . :
: ,. . - ~ ,.
Wog0/09~72 PCT/US90/00584
Generally, these situations demand ~hat the
sample be stored for later analysis by sophisticated
separation technology and analytical techniques. In
addition, the analyte concentration is expected to be
very low because ~he sample may be collected hours after
exposure or it may be pre~ent in only trace amounts. For
example breath levels of such analytes are measured in
the parts-per-billion to parts-per-million range. In
order to accurately measure such levels and to establish
standards to deal with such small amounts, a breath
sampling technique should permit concentration of the
analyte. In addition, the device should be compact
enough to allow shipment to the laboratory for analysis
i~ on-site analysis is not performed.
The above and other objects and the nature and
advantages of the present invention will become apparent
from the following detailed description of certain
specific embodiments taken in conjunction with the draw-
ing, wherein:
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a detailed schematic illustration
of a first configuration o~ the sampling device of the
present invention;
Figure 2 is a detailed schematic illustration
of a second configuration of the sampling device of the
present invention;
Figure 3 is a detailed schematic illustration
of a modification of the sampling device configuration
shown in Figure 2;
Figure 4 is an exploded view of the components
of one embodiment of the sampling canister contemplated
for use with any of the embodiments of the sampling
devices shown in Figures 1, 2, or 3;
Figure 5 is an exploded view of the components
of a second embodiment o~ a sampling canister which can
be used with any of the embodiments of the sampling
devices shown in Figures 1, 2, or 3;
,,,: : - ............. , ., .: .- .
. - -: . - ... ~:
-- - ~
W090/09;72 ~ A, ?"~Q~3
i..~ -
_ g _
Figures 6 and 7 show a tool which can be usedto load the check valves used with ~he sampling devices
of the present in~ention;
Figures 8 and 9 show another similar tool,
Figure 9 being a schematic view showing use of such tool
in use;
Figure lG is a schematic ~iew of an improved
sample canister for granular sorbents and/or combination
of charcoal cloth and granular sorbents;
Figure 11 is a schematic view of another
improved sample canister for granular sorbents; and
Figure 12 is a schematic view of another
alveolar sampler using granular sorbents.
Figure 13 i5 a schematic view of a mainstream
sample canister thak is primarily intended for perma-
nently containing the charcoal cloth or granular sor-
bents.
Figure 14 is an "L"-shaped configuration of the
sampler, which further minimizes void volume.
Figure 15 is a schematic view of a square main-
strea~ sample canister.
Figure 16 shows the construction of a removable
square container for granular sorbents.
Figure 17 shows the construction of a square
container fox use with removable charcoal cloth sorbents.
Figure 18 shows a dose receiving samplex
designed for the subject to use while exposed to the
analyte gas. However, in order for the dose to be
extimated the inhalation canister is first removed.
Otherwise, this sampler may be used for mixed-expired
sampling as the samplers described in Figures 1 and 2.
Figure 19 shows a sample canister wi~h sorbent
for alternate use in the system oî Figure 4.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing, it will be under-
stood that while the present invention may be embodied in
a variety of configurations, for purposes of illustration
.
` '
~O90/09~72 PCT/US90/00;84
2 ~ o - i
two oonfigurations will be discussed below, namely a "Y"
configuration and "T" configuration, as well as a varia-
tion of the latter. All of these confiyurations can be
used for di~ferent types of sampling, although a particu-
5 lar configuration may provide advantages relative to aparticular type o sampling. Thus/ the "Y" configuration
shown in Figure 1 minimizes the void volume as much as
possi~le within manufacturing tolerances, thereby mini-
mizing rebreathing of partially delivered samples from
the ~oid volume of the sampler device. The "T" config-
uration shown in Figure 2 enables collection of both
mixed-expired and end-expired samples using a single
collection canis~er~ The ~ariation of Figure 3 is
primarily intended for single breath end-expired
sampling, although it can also be used for single breath
mixed-expired sampling. For all these configurations,
the present invention contemplates that, subsequent to
collection of the breath sample, analysis for the
analytes contained in the collection canister will be
made with conventional analysis equipment.
Looking first at Figure 1, the sampling device
100 involves a main body 110 having a tubular mouthpiece
support portion 120 on which a bite wing mouthpiece, such
as shown in Figure 2, may be mounted, an inhalation can-
ister support portion 130 for attaching a charcoalinhalation canister 140, a sample canister attachment
portion 150 for attachment of a sample canister 160, and
a sidestream port 170 for collection of sidestream sam-
ples. The port 170 is disposed substantially centrally
of the main body and opens into the main body rom one
side thereof. Sidestxeam samples may be collected on
sorbents contained in stainless steel or glass tubes
attached to the port 170 via appropriate ferrules and
fittings, or other similar mechanical connec~ion means.
3s The inhalation canister support portion 130 comprises a
two part structure including a first tubular part 132
formed as an integral part of the main body and extending
': ? - : .
W090/09572 - Pcr/us9o/oo584
,: .
;L 9--5i
(i.e. having a longitudinal axis extending) at an ~ngle
of about 120 from the longitudinal axis of the tubular
mouthpiece support portion 120. The fixst tubular part
132 includes an annular end face disposed in a plane
S perpendicular to the longitudinal axis of the first tubu-
lar part 132.
The inhalation canister support portion 130
also includes a second tubular part 133 having at one end
an annular face matching the surface area and configura-
tion of the end face of the first tubular part. Thefirst and second tubular parts are secured to one
another, with their annular end faces disposed in opposi-
tion to one another, via a clamp means. In ef f ecting
this connection, an annular gland or seal 134 is disposed
and maintained between and spaces the end faces from one
another. Various materials are effective for use as the
seal; however, the preferred material is polytetrafluor-
ethylene-covered silicone rubber.
The second tubular part includes an annular
~0 edge positioned forwardly of the clamped, sealed end
faces, and the forwardmost end 136 of the second tubular
part is provided with a threaded inner or outer surface
142 for making threaded engagement with a complementarily
threaded outer or inner surface 142 on the charcoal
inhalation canister 140, thereby insuring that the can-
ister 140 is securely attached to ~he second tubular
part. An inlet check valve 180, having a twofold func-
tion, is disposed on the annular lsdge 135. The major
functions of the inlet chec~ val~e 180 are: (1) to open
under negative pressure (inhalation) thus permitting the
user to inhale from the ambient through the inhalation
canister 140; (2) to close under pressure and thereby
prevent exhaled air from escaping from the main body of
the sampler back through the inhalation canister 140; and
(3) to direct the exhaled sample through the sample bed
in section 160 of the sampler.
The sample canister support portion 150
W090/09372 PC~/US90/00584
.
2~ 5 - 12 _
includes a first ~anister housing part 151, a second can~
ister retaining part 152 and a third housing par~ 153 for
engagement of a volume measuring d~vice (not shown, but
to be discussed la~er~ The first housing part 151 com-
prised a tubular member~ formed integrally with t~e mainbody and having a longitudinal axis disposed at approx-
imately 120 from the longitudinal axis of both the
inhalation canister support portion 132 and the mouth-
piece support portion 120, and an annular sleeve 155
attached at the forward end of the tubular member.
Sleeve 155 is provided with a forward facing annular l~nd
154 for retaining a first polytetrafluoroethylene (PTFE
or "Teflon") gasket Tl and a forwardly extending annular
c~ff 156 bearing a set of internal threads.
Housed within a sleeve 155 forwardly of the
land 154 is a sample canister 160. Secured by threads
within cu~f 156 is the externally threaded, rearwardly
facing, annular extension 157 of the canister retaining
part 152. A second PTFE gasket T2 is supported on the
forward facing land 150 of retaining part 152, and the
sample canister is held securely between th~ PTFE gaskets
Tl, T2 within sleeve 155 when the retaining part 152 is
threaded tightly in a rearward direction and within the
slee~e 155. The housing part 153, secured within the
forward end of retaining part 152 by a welded connection,
comprises an annular sleeve member having a forwardly
facing annular seat 159 at its rearward end. Disposed
on, and secured to, the annular seat 159 is an outlet
check valve 190 having a constructiorL which is the same
as that of inlet check valve 180
~ 'he major functions of the outlet check valve
190 are as follows: (1) to close under negative pressure
(inhalation) and prevent environmental contaminants from
entering the sampler body; (2) to open under positive
3i pressure (exhalation) and thereby permit the sample
stream to pass through the sample bed in section 150 of
the sampler; and (3) to direct the exhaled sample through
,, - ~ , .
.
.
WO 90/09;7'' F'CI/US90/00584
~r~
-- 13 --
the sample bed in section 160 of the sampler.
Each check valve 180, 190 comprises a one-way
diaphragm-type val~e with an integral cross-hatch
support. Welded to the center of the support is a
retainer bud for the valve diaphragm. The cross-hat~h
support is of the type known as a "low flow resistance"
cross-hatch, is made of stainless steel, and is sil~er~
soldered to a land at the respective inlet ox outlet
location. The purpose of the cross-hatch support is to
provide a retention foundation for the respective
diaphragm valve during inhalation or exhalation.
- Figure 2 illustrates a second breath sampler
device 2G0 exhibiting the "T" configuration described
above which facilitates obtaining mixed-expired breath
samples. This second device includes a tubular main body
210 to which a stainless steel compression fitting 212 is
secured (via welding) at an opening substantially cen-
tered in the tubular main body 210. The fitting 212 is
provided to facilitate the collection of sidestream sam-
ples, and it is to be understood that the diameter of thefitting may be chosen as a function of the particular
application or task to be accomplished. One side of the
tubular main body 210 (hereinafter referred to as the
"inlet" side) supports, via a first threaded connection
means 214, an inhalation canister 230. An inlet check
valve 215 is located downstream of the threaded connec-
tion means 214. Directly opposite the inlet side of the
main body is the "outlet" side where the sampling can-
ister 240 i~; located and supportéd on the main body via a
second threaded connection 216. An outlet check valve
217 is posîtioned downstream of the second threaded con-
nection. In Figure 2, the inlet canis~er, the mol1thpiece
support and the sample canister are shown attached to the
sampler main body 210 by threaded connections~ However,
these connections could also be accomplished by use of
alternative fittings e.g. tapered sleeve- or O-ring type
slip fittings.
i
. . . .. : . - . -~
:~ , ' ' ~ ': -
-, ~.. . .
- : ~ . ~, ...
WO 90/09572 PCr/lJS90/00;~34
,.,
14 - ~
Typically, both the inlet ~d outlet check
valve bodies are fabricated from stainless steel discs.
A plurality of openings (four equiangularly spaced open-
ings in the preferred embodiment) are provided in the
discs to form an ~rray which facilitates air flow through
the discs. Retainer ~uds are welded directly to the
center of the discs to assist in securing the silicone
rubber diaphragms against dislodgement. On the down-
stream side of outlet check valve 217 is a kapered con-
nection 218 which connects directly to a respirometer 250used to measure and record the volumes of exhaled
breath. This connection has been made to facilitate
connection to the respirometer; but other volumetric
devices may be used by connecting them with suitable
fittings and connections to the tapered connection 218.
Through a third threaded connection 219, a tubular mouth-
piece support portion 220 is coupled to the main body 210
of the sampler device. A bitewing mouthpiece 260
includes an elongated sleeve portion 262 adapted to be
mounted over the tubular mouthpiece support portion 220,
and a mouth engaging portion 264.
The mouthpiece support portion 220 may also be
directly connected to the sampling canister 240, as seen
in Figure 3. This modification of the Figure 2
configura~ion facilitates single-breath "end-expired"
collection of samples. It should therefore be clear that
both the "mixed-expired" sampling device shown in Figure
2, and the "end-expired" sampling device shown in Figure
3, are desiS~ned so that either one will fit with the same
mouthpiece support portion. The support acts as the
mouthpiece for the configuration shown in Figure 3. In
both of the Figure 2 and Figure 3 embodiments of the
sampling device, the inlet and outlet check valves
employed are substantially identical with those used in
the sampling device of Figure 1. Moreover, the sampling
canister 240 used in the embodiments of Figures 2 and 3
is preferably substantially the same as that described
.
.. . ..
. .
WO90/09572 PCT/US90tO0584
1 -- 2 ~
- 15 -
above for use with the embodiment of Figure 1.
The design may be L-shaped s shown in Figure
l4. This embodiment minimizes sampler void volume and
permits the sample canister to be directly in the path of
the exhaled sample so that there are not angles which
produce bac~ pressure and turbulene which under certain
circumstances may b~ undesirable.
Because of its construction, the Y-configured
sampler shown in Figure 1 is particularly constructed for
continuous mixed-expired breath sampling. This was the
prototype sampler. It is the most expensive and least
flexible of the illustrated embodiments. The inhalation
canister 140 is attached to the main body of the sampler
110 via a Tri-clover clamp 134. This cl~mp permits the
inhalation canister assembly to be removed from the main
sampler body in order for the inlet check valve (180) to
be replaced. Unless a single sampler is dedicated ~o
each subject, the Y design, as configured in Figure 1,
also requires that t~e sample canister (stack) be removed
and stored immediately after sampling. This introduces
the possibility of passive sampliny of contaminants in
the industrial environmen~ by the charcoal cloth sorbent
and may limit the reliability of the sample.
In order to avoid the use of the Tri-clover
clamp, reduce fabrication costs and to make the sampler
more flexible, the sampler shown in Figure 2 was
created. In that sampler, the threaded inhalation can-
ister support (214 of Figure 2) is welded to the main
body of t~.e T, eliminating the need for a Tri-clover
clamp and substantially reducing fabrication costs. A
conventional stainless steel pipe "T" may be used as the
main body of the sampler. In addition, this construction
places the removable sampling cup in a canister that may
be removed from the main body of the sampler and shipped
off for analysis. This canister may also be directly
attached to the respirometer via the tapered fitting (218
of Figure 2). As configured in Figure 2, the sampler
- - . ~ .
:
W090~9572 PCT/US90/00584
~ 16 -
permits continuous mixed-expired breath sampling ~main-
stream or sidestream) just as does the sampler in Figure
1. However, when the sampler of Figure 2 is disassembled
and re-configured to the sa~.pler of Figure 3, single
breath end-expired (or for that matter single-breath
mixed-expired) samples may be obtainedO
In the sampler of Figure 2, the inhalation
canister support 214 cannot be separated from the main
sampler body to permit loading of the inlet check
valve. The outlet check valve 217 is in a deep,
inacc~ssible chamber of the sample canister. There~ore,
a means of loading the inlet check valve into the sampler
body and the outlet check valve into the sample canister
is desirable. That is the purpose of the loading tool
shown in Figures 6 and 7. The use of this tool actually
dictates the "T" configuration of the sampler in Figure
2, or the L-shaped configuration in Figure 18, because of
the necessity to permit ready accessibility of the chec~
valve loading tool to the inlet check valve support
through the opening at 216 in Figure 2. Hawever, a
Universal Check Valve Loading Tool (see below) has been
created to allow the inlet check valve to be loaded into
a Y-shaped main body or an L-shaped main body that has no
access port. There~ore, it is also possible to replace
the T~shaped main body of the sampler in Figure 2 with a
lower void volume L-shaped or Y-shaped main body, while
still retaining the flexibility of the T-shaped design.
All that is required for this purpose is to machine the
main samp~er body from a Y-shaped pipe fitting or fabri-
cate the body in an L-shape or to cast the body in a Y or
~-shape.
In summary, the Y, the L and the T configura-
tions permit mixed-expired sampling. The particular Y
design as shown in Figure l permits only mixed-expired
sampling because it is not shown with a removable sample
canister and mouthpiece as is the T-shaped design of
Figure 2. However, there is nothing intrinsic in the
~ . . .
.' ' ' ' .. ' .
Wogo/09s72 PCT/US90/OOSB4
- 17 ~
design of a Y-shaped sampler that would pe~mit only
mixed-expired sampling, e.g. the Y-shaped sampler of
Figure 1 can be aasily adapted as noted above for
obtaining single ~reath end-expired or mixed-expired
samples.
Figure 4 illustrates the structural elements
contained within one embodiment of the sampling canister
used in the present invention. PTFE gaskets 402 and 402'
are positioned at the top and bottom of the stack of
elements. The gaskets provide a secure seal around the
canister after it has been loaded into the sampler
device. The sampling "stack" further includes ~ cylin-
drical torous weight or retainer 404, a first stainless
steel retainer screen 406, charcoal cloth sorbent bed
15 408, and a second stainless steel retainer screen 410.
The weight or retainer 404 retains sorbent bed 408 in the'
canister by compressing the first retainer screen 406
against bed 408. To prevent inhalation of sorbent fines,
a second retainer screen 410 having a fine mesh is placed
20 atop the array of openings 413 in the canister 412. The
openings 413 preferably are provided in symmetrical array
to form a grating.
~he sampler canister 412 into which the stack
of elements fits is designed to accommodate a large plur-
ality of wafers of charcoal cloth of which the sorbent
bed 408 is comprised (one embodiment contemplates element
(11) wafers), including if necessary or desired, stain- '
less stee~ screens for separating the adjacent sorbent
wafers. kn anti-rotation lug 414 is provided (e.g., via
spot welding) on the interior of the annular wall of the
canister. The lug 414 engages with the cutout 405 pro-
vided in the exterior annular surface of the torous
weight 404 for preventing the weight from rotating the
retainer screen 406 as the canisker is being loaded into
the sampler housing. In this way, the sorbent bed is
protected against being torn and the formation of fines
during loading of the canister is prevented.
~` ' - - ' . .
~090/09572 P~T/US90/U0584
18 ~
A second embodiment of the sampler canister,
which is illustrated in Figure 5, is contemplated for use
with ~he embodiments o~ sampling devices shown in Figures
1, 2 ox 3. This embodiment shows the use of charcoal
cloth sorbents, although granular sorbents, such as
silica gels or porous polymers could also be used. The
canistsr comprises an assembly of elements including a
torous shaped weight or retainer 504, a ~irst retainer
screen 506, a first sorbent bed 508, a second retainer
screen 510, a second sorbent bed 516 and a third retainer
screen 518. This assembly of elemen~s is disposed within
a stainless steel canister cup 512 having a bottom per-
forated with an array 513 of openings~ An anti-
rotational lug 514 is provided on the annular surface of
the cup for engagement in the anti-rotational cutout 505
provided on the annular outer surface of the torous
retainer 504.
As with the first embodiment of sampler can-
ister illustrated in Figure 4 and described above, two
~0 gaskets 502, 502' are positioned atop and below the
sampler canister to provide a secure seal around the
canister once it has been loaded into the sampler
de~ice. By using this second embodiment o~ sampler can-
ister, granular sorbents may be held in the cup 512 by
25 the first, second and third retainer screens (506, 510
and 518, respectively), or by the use of discs of very
fine mesh stainless steel which are centered on, and
soldered or welded to, a thin metal ring. Alternatively,
the discs could be press-fit to and about the thin metal
ring. Preferably, the outer diameter of the ring would
be about equal to the inner diameter of the cup.
Sorbents may be separated into front and back sections,
and may be retained in place using the discs or the
screens.
In embodiments of the sampler device shown, the
stainless steel canister cup may be eliminated from the
canister housing or support member, and alternatively
WO90/09572 PCT/US90/00584
9~v ~
perforated discs o stainless steel may be welded to the
inside of the canister housing or support member to form
an equivalent cup base or bottom, and ~herea~ter the
sorbent beds and screens can be assembled to form the
sampler canister.
In operation, the sampler devices shown in
Figures l and 2 function in the sam2 manner as a
respirator mask. The subject (user), wearing a nose
clamp and biting a bitewing mouthpiece, is instructed to
breathe by mouth only. At the beginning of inhalation,
negative pressure created inside the main body of the
sampler closes the outlet or exhalation check val~e and
opens the inlet or inhalation check valve, thereby
permitting fresh air to be drawn through the charcoal
canister (140 in Figure 1 and 230 in Figure 2). When the
subject exhales, the positive pressure created in the
sampler main body forces the inlet bhec~ valve to close
and the outlet check valve to open. Volatile compounds
in the-subject's breath are adsorbed from the mainstream
gas flow on the charcoal cloth sorbent medium or granular
sorbent medium in the sample canister, or from the
sidestream flow using other sorbents.
For collection of mainstream breath samples,
exhaled volumes may be recorded using a Wright respiro-
meter or other volumetric device. For sampling breathfrom the sidestream, the sample volume is recorded by
multiplying the duration of sampling by the sampling
flowrate, and then by a correction factor that accounts
for the percent of time the subject spends exhaling.
Laboratory studies have shown that such a correction
factor is approximately 0.65. Other techniques to esti-
mate sidestream sample concentration may also be used.
Tests with volunteers have shown that sidestream carbon
dioxide concentrations are approximately 71% of main-
stream concentrations. Therefore, the sidestream sampleconcentration may be estimated by determining the mass
sampled, dividing that mass by the volume sampled (i.e.
.
, . ~ . . .:, :
W090,'09~72 ~ PCT/US90/00584
- 20 -
actual sidestream flowrate x time), and then dividing
that concentration by 0.71 to correct approximately to
mainstream concentrations.
Either the mainstream, or the sidestream, mode
of sampling permits large volu~es o~ mixed-exhaled breath
to be sampled without prior collection in and concentra-
tion from a yas-sample bagO In this way sufficient
quantities of the absorbed compounds are permitted to be
. collected for analysis.
The check valves disclosed in each of ~he
embodiments of the sampler device, i.e., the embodiments
shown in Figures 1-3, can either be removable or non-
removable. Non-removable valves could be secured, as by
a press-fit or by welding, to their respective supporting
structures. Removable check valves might be desirable
where frequent cleaning of the valves is required, or
where the contemplated cleaning process for the valves
would not be practically carried out with the valves
secured within their respective sampling devices.
While the outlet check valve has been shown in
each of the embodiments to be placed in a specif-ic loca-
tion, it is possible to have the outlet check valve dis-
posed in still other locations. For example it may be
useful to place the outlet check valve upstream of the
sampler canister. Without the sample canister attached
the subject may flush his lungs free of environmentally-
contaminated air for a prescri~ed period, by inhaling
fresh purified air through the inhalation canister or
other air source and venting the exhaled air to the
atmosphere ~hrough the outlet check valve. Thereafter
the sampler canister is attached to the sampler. The
concentrations of the samples are then reflective only of
bloodstream contamination levels and not of environmental
contamination levels.
Figures 6 and 7 disclose a valve mounting tool,
the use of which is for loading check valve diaphragms of
the kind which can be removed from the sampler devices of
... . .. ...
.,..
WO90/09;7~ PCT/US90100584
- 21 -
the present invention. Figure 6 illustrates the tool in
a position in which a check valve has been inserted in
preparation or mounting in a sampler device, while
Figure 7 illustrates the tool in a position in which the
check valve has been mounted
As shown in Figures 6 and 7, the tool 600 com-
prises an elongated guide tube 610 having a first push
rod insertion end 612 and a second check valve supporting
end 614. The length of the guide tube 610 is signifi-
cantly greater than its diameter, and supports in itsinterior an elonyated push rod 640. An elongated cutout
or slot 620 extends, from a location adjacent the second
end 614 of the guide tube, along a short length of the
guide tube in a direction towards the first end 612
thereof. A narrow strap of thin gauge metal 611 (prefer-
ably, stainless steel) is welded to one end of the push
rod 640 which is inserted into and housed within the
guide tube 610. Prior to insertion of the rod 640 into
the guide tube 610, one free end of the strap is welded
to the center of the circular peripheral edge surace of
the one end of the push rod to lie adjacent to the longi-
tudinal extent of the push rod. The other end of the
strap further protrudes diametrically through the cutout
and is welded to the inner annular surface of an outer
sleeve member 650, which is disposed over and rides along
the exterior of the guide tube 610.
In order to load the inlet or outlet check
valves, the outer sleeve member 650 is moved rearwardly
(to the right in Figures 6 and 7) over the guide tube 610
by the push rod 640. The check valve to be loaded is
then pushed over the guide tube 610 and is retained in
any suitable manner, e.g. the check valve can be made of
a resilient or elastic material which deforms or makes a
friction fit with the guide tube.
The second end 614 of guide tube 610 is
inserted into the inlet or outlet check valve mounting
structure (in each of the sampler embodiments disclosed
: .
. . .
~: . ~ : : ,: -.
: . . :: . . -
woso/09~72 PCT/US90/00584
- ~ - 22 -
above) such that the guide tube is disposed over the
retainer bud. The pushrod 640 is then pushed back
through the guide tu~e 610 so that the outer sleeve mem-
ber 650 engages ~he check valve and pushes it from the
guide tube onto the retainer stem.
Removal of ~he check valve may be effected by
using long term tweezers, or some equi~alent toolO
In the sampler devices described hereinabove,
the exhaled volume of the mainstream sample is determined
using an accurate volume measurement device, as for exam
ple a Wright respirometer. ~olume measurements made are
independent of the use of an inaccurate and imprecise
technique e.g. collection of exhaled w~ter on a high
pressure drop adsoxben~, such as molecular sieves, where
the amount of exhaled water collected must be assumed to
be directly proportional to the volume exhaled.
The foregoing sampler devices permit side-
stream, as well as mainstream, sampling. Sidestream
sampling is important, and a capability for conducting
this mode of sampling has been designed into the sampler
devices of the present invention, for several reasons:
(1) Although ~he pressure drop associated with
a charcoal cloth sorbent bed is low, subjects with
respiratory problems may not be able to exhale through a
sorbent bed.
(2) Sampling from the sidestream enables the
user to employ sorbents that are selective to the collec-
tion and analysis of specific analytes. For example,
research has indicated that alcohols are only poorly
recovered ~rom charcoal cloth, and it may thus be neces-
sary to use sidestream sampling for collection of such
analytes.
(3) The capacity of the charcoal cloth sorbent
bed for high vapor pressure solvents such as methylene
chloride may be limited. Sidestream samples can be
collected at any desired flowrate on the sorbent of
choice, such that problems with breakthrough are
. . .. . ~ .., ..~ .. -
:- .:. : . ,,: .
WO90/0957~ PCT/US90/~0584
_ ~3 -
minimized.
(4) Multiple, and theref ore replicate, samples
may be obtained using the sidestre~m sampling option.
One or more sorbents may be used to trap selective
analytes a~ a variety of flowrates.
(5~ The sidestream port enables the sampler to
be connected to an appropriate continuous monitor for
breath-by-breath measurements. In this manner, the side-
stream port facilitates frequent and continuous analysis
of hreath samples which are uncontaminated by the
analytes in the work environment.
(6) Pressure- or flow-sensors may be connected
to the sidestream port to measure the number of breaths
and or the pressure/flow profile of each breath.
In order to permit a low void volume Y-shaped
design for the main sampler body that does not have a
removable chec~ valve assembly, it is necessary to employ
a valve-loading tool as shown in Figure 8 similar in
function to that shown in Figures 6 and 7.
Referring to Figure 8, two hollow cylinders (A)
and (B) are used as guide tubes and are connected at a
hinged joint (C). As configured, the two guide tubes (A)
and (B) may be rotated relative to one another by approx-
imately 120 in order to assure the proper angle of
orientation of the tool relative to the retainer bud when
the tool is inserted in the sampler body. However other
angular orientations are also possible for example 90
for use with an ~-shaped sampler that has no side access
port. The hinge (C) must be relatively "stiff" and a
positive istop" attached to the guide tube (B) (see
Figure g), in order to prevent the two guide tubes from
being bent at an angle greater than 120 or other pre-
ferred angle relative to one another. The ~top is a
small metal stud welded to the body of tube (B), just
above the hinge. The push rod (D) is a cylinder housed
in a long (A) section of the guide tube. An outer sleeve
(E) slides over the other (B) section guide tube and is
, ",~"""~ ,.". ~,." ~
W090/09572 PC~/~S90/00584
~ 24 -
welded to a short metal tang (F). A slot (G~ has been
cut înto guide tube (B). The tang slips ~hrough the slot
(G) inside of tube (B). A relatively sti~f cable (H)
connects khe pushrod (D) to the tang (G)o At one end,
the cable is welded or press-fit to the push rod (D). At
the other end, the cable is welded or pressfit to the
tang (F)o
The tool operates in the same way as the tool
described in Figures 5 and 6. That is, the outer sleeve
(E) is pulled back over the guide tube by pulling the
push rod (D) back to the loading position. The check
valve is then slipped onto tube (B)~ Section (B) of the
tool is then inserted into the body of the sampler and
forced up against the inner wall of the sampler body to
bend the tool at the hinge (C) to approximately 120 or
other preferred angle. The (B) section guide tube is
then ~orced over the retainer bud. The pushrod ~D) is
pushed, forcing the cable (H) through guide tubes ~A) and
(B), causing the outer sleeve (E) to slide along outside
of guide tube B, thus pushing the check valve onto the
check valve support. To improve functioning, inner cable
guides as shown in Figure 8 may also be used.
One embodiment of a sample canister for granu-
lar sorbents and for combinations of granular sorbents
and charcoal cloth is shown in Figure 10. In this con-
figuration, the sorbent beds are retained in separate
canisters of the type 517 shown in Figure 5. Alterna-
tively, this embodiment may also be used to retain
several, e.g. primary, secondary and even tertiary, beds
of charcoal cloth sorbent. However, in order to minimize
pressure d~ops caused by large amounts of granular
sorbent, it is preferred that the retainer cup not be as
deep as that used for charcoal cloth sampling in pre-
viously discussed embodiments. The canisters are stacked
atop one another as shown in Figure 10. This arrangement
permits a more positive seal of granular sorbent beds
into the canister than are provided by those in the
..
.
. , . :: . ~:, ,
:. . . : ~ :, ; .
.. :: ., ~ . - . ~ .
: , .... . .. :.. .. . .
~: .~ . : -: . :
.:, - .: -
WO90/09i72 P~T/US90/00584
,,,, ~,
25 ~ ' ,~ hi;,~
pre~ious embodimen~s of Figuxes 4 and 5. There should be
no possibility of granular sorbent from one sorbent
section being accidentally mixed together with that of
another sorbent section by spillage. Granular sorbent is
retained in each of the cups by the fine-mesh stainless
steel screens that are spot welded to the inside base of
the cup (over the grating) and to the bottom of the heavy
retainer grating.
These heavy retainer gratinys serve to flatten
the sorbent bed and thus prevent channeling during
sampling. They essentially replace the torous weight of
the previous embodiment. However, this construction does
not include an anti-rotational lug in the sampler cup to
engage a cut out on the heavy stainless steel grating as
with the previous embodiment. Granular sorbents require
a very tight seal to be held in place. ~he sorbent may
be blown or fall out of the sampler past such an open-
ing. Essentially, this is a cup-in-a-cup design. It may
also be desirable to ensure that the individual sorbent
beds be separated or sealed by Teflon gasXets as shown in
Figure 10.
Alternatively, the granular sorbents may be
used with a canister such as that shown in Figure 11,
this canister has also been fabricated from two stainless
steel cups~ an upper (A) and a lower (B). The outside
diameter of the upper cup is approximately equal in the
inside diameter of the lower cup. Fine-mesh retainer
screens (C) (diameter = internal diameter of the upper
cup) have ~een spot-welded over the grating in the inside
of both CU~5 . In addition, a retainer ring (D) has been
press fit into the upper cup as shown. The entire upper
assembly is then inverted and press-fit into the lower
cup. Once press-fit together the two cups, A and B, are
permanently affixed to one another. The granular sor-
bents may be added or removed from the canister from aport (E) that is drilled into the side of the assembled
canister, the hole may be threaded. This port is plugged
; , - ~
,. .. . .
..
WO 90/09572 PCl /US90/00;~4
~ ~ rl r, ~ 26 -
with a threaded metal plug or a small plug of silanized
glass wool or ~ teflon plug once the canister has been
filled with sorbent. Dimensions are as shown on Figure
11 .
S Along thase same lines, another embodiment is
shown in Figure 12 for another alveolar sampler which
also employs granular sorbentsO This device is primarily
intended for sampling extremely low concentrations of
solvents in alveolar breath. Samples of alveolar air
collected with the device are primarily intended to be
analyzed by thermal desorption. Thermal desorbers are
commercially available and used extensively in environ-
mental monitoring. For sampling, stainless steel or
glass ~ubes, generally ranging in diameter from 0.25" to
0.625N are loaded with a sorbent. The manual breath
sampling technique is used with this device. The subject
exhales the end portion of the breath sample into the
sorbent bed. The contaminants present in the air are
trapped on the sorbent. The tube is capped and returned
to the laboratory for analysis. During analysis, the
tube is inserted into the thermal desorber where it is
heated under a stream of inert gas such as nitrogen.
This flushes the trapped sol~ent(s) from the sorbent into
a gas chromatograph where it is analyzed. The major
advantage of thermal de~orption is that all of the
solvent is removed from the sorbent bed by the thermal
desorption process, and injected into the chromatograph
for analysis. ~his contrasts with solvent desorption
where the sample is diluted with solvent and only a very
small portion of the sample is injected into the analyti-
cal instrument. Thus, thermal desorption significantly
enhances sensitivity relative to solvent desorption and
permits the analysis of much lower quantities of analyte
than would be possible for analysis by solvent desorp-
tion.
The sampler o~ Figure 12 described below isadapted for use with a 0.625" O.D. x 0.579" I,D. x 7.0"
. .. .: - ,
WogO/09572 PCT/US90/00i84
9 ~
- ~7 -
long stainless steel thermal desorption tube, i.e. the
type that is used with a ~ekmar~ thermal desorber. The
solvents present in the breath are sampled on beds of a
porous polymer such as ~enax~; however, many other sor-
bents including charcoal cloth may be used for this pur-
pose. This device is primaxily intended to be used where
the concentration of sample in al~eolar breath is very
low. Again, both ~ront and bacX absorbing sections are
used. The device is configured similarly to the granular
10 sample canister shown in Figure 10. The 0.625" OD
thermal desorber tube is welded as shown to a 0.866" (22-
mm) tapered adaptor (A), -to form the main body of the
sampler. The tapered adaptor permits ready attachment of
the sampler to a Wright respirometer. The sorbent is
retained in primary and backup stainless steel cartridges
(B and B' respectively) that are approximately 0.579"
OD. The bottom of each cartridge is a grating to which
fine mesh stainless steel screen has been spot welded on
the inside. At the top of each oartridge ar~ separate
heavy stainless steel retainer grating (C and C' for the
primary and backup sections respectively). Fine-mesh
stainless steel screen i5 spot-welded to the bottom of
each grating. These gratins slip inside the sample
cartri~ges and retain the sorbenk bed in place. Alterna-
tively, plugs of silanized glass wool may be used inplace of these gratings.
The sampler is loaded as follows: first, the
backup cartridge (B') is slipped into the sampler body.
The backup cartridge rests on a land ~D) at the bottom of
the cylinder housing. A Teflon gasket (E') is inserted
above the backup cartridge. The primary sorbent
cartridge (B) is then inserted. Another Teflon gasket
(E) is placed behind the front cartridge. Once inserted,
the cartridges are held in place in the sampler body by a
retainer tube (approximately 0,579 a OD) (F) that com-
presses against the upper stainless steel retainer grat-
ing as shown. There are holes in the retainer tube (at
. : .. .
~,, , -
WOgO/09572 PCT/US90/0058
~ 28 -
I ) and in the main body of ~he sampler (at H). As the
retainer tube is inserted into ~he main sampler body, the
holes on the retainer tube and on the main samplex body
are aligned and a small threaded retainer key (H) is
inserted through the hole in the outer sampler body and
int~ the matching hole on the inner ratainer tube. This
arrangement locks the canisters into place and keeps ~he
entire assembly tight.
Once sampling is completed, the sampler is
returned to the laboratory for analysis. The sampler is
disassembled by first removing the threaded retainer
key. The entire assembly including the retainer cylin-
der, the primary backup sample cartridges and the Teflon
gaske~s are then removed by pushing the sample cartridges
out of the sampler with a convenient tool (e.g., a solid
rod) from the open end of the sampler body welded to the
adaptor (A).
Each of the cartridges are then separately
inserted into a 0.579" ID thermal desorber tube to which
a land such as D of Figure 11 has been welded. The
cartridges would be inserted such that they rested atop
~he land. Each cartridge is then separately analyzed by
placing the assembly inside a thermal desorber oven unit
for analysis.
Although I have specified thermal desorption as
the mosk d~si~able desorption procedure, other techniques
for recovering the solvent from the sorbent, e.g. solvent
desorption or extraction with supercritical fluids, may
also be used as applicable.
~lnlike some other sorbent containers, the con-
tainer o~ Figure 13 can be made so it cannot be dis-
assembled. It is primarily intended for use in an
occupational health clinic where complaints regarding
exposure may be substantiated, perhaps several days post-
exposure by sampling a large volume of breath using such
a container. Since the sorbent cannot be readily removed
from the container for solvent desorption, it is
-:
WO90/09572 PCT/US90tO0584
3~9
- 29 -
preferred that the sample be desorbed by thermal means or
using supercritical fluids.
The canister of Figure 15 can essentially
replace canister 240 in Figure 2. It is preferred th t
this cannot be constructed of inert materials which do
not sorb volatiles such as stainless steel, anodized
aluminum, or PTFE (Teflon~). Here the body of the sample
canister does not have to be dividsd into threaded male
and female components as does the canister of Figures 1,
2 and 30 Rather than separating the two halves of the
canister to insert the sorbent container(s) such as part
412 in Figure 4, the cover on the top of the sampling
chamber is removed and individual sample containers
- inserted. A retainer shim has also been included in the
sampler arrangement. For ease of viewing, this retainer
shim i5 shown outside the body of the sampler. Alterna-
tively, the shim may be permanently held in place at the
outlet end of the body of the sampler using the retainer
bolts shown. Its purpose is to seal the individual
sample containers against one another during use. The
sorbent containers are loosely inserted into the can-
ister. The two retainer bolts on the backside of the
canister body are then tightened against the shim forcing
it against the sorbent containers. ~his arrangement
should also ~acilitate the recovery of the sorbent con-
tainer from the canister, as the user would not need to
forcibly xemove tight fitting sample containers from the
canister, but simply release the retainer shim and xemove
the sample containers. In addition, it allows ready use
of oversized or multi-depth sample containers.
As shown in Figure 15, the cover is mounted to
the sampler body with screws; a gasket is used to seal
the cover with the body. Alternatively, the cover may be
mounted to the sampler body by sliding it in a track
mounted to the top or that body or sealed in place with a
clamp. A reason for this arrangement is to permlt ready
use of granular sorbents. The granular sorbent is
", ," ",~
WogO/09~72 PCT/US90/005~4
~ 30 _ ~ ,
compressed in place with the weights shown to prevent
channeling through the sorbent bed during sampling.
However, the sorbe~t container may also be used with
charcoal such as charcoal cloth in three~wafer
sections. In addition, this permits the use of double-
size sorbent containers for granular sorbents weighted as
necessary with oversize weights.
The arrangement has a further advantage of
reducing waste of the charcoal cloth sorbent and of the
fine mesh retalner screen. Cut~ing circular wafers of
charcoal cloth or fine mesh screen from a rectangular
roll of sheet stock does not allow all of that stock to
be used whereas the use of square or rectangular wafexs
will.
The container channel support of Figure l6 may
be fabricated separately from stainless steel- or
aluminum-channel stock. The front and back fine mesh
stainless steel screens are approximately 40-mm square,
giving approximately the same exposed surface area as
that of the currently proposed 45 mm diameter wafers of
charcoal cloth. These screens are inserted into the
protruding arms of the channel support. The inner shim
assembly is then forced as shown into the channel support
to retain the screen in place. In order to stabilize the
assembly, the outer channel support may be spot-welded or
bolted to the inner retainer shim.
The container channel support of Figure 17 is
fabxicated as described a~ove for granular sorbents;
however, it may not be as deep as the channel support
since the charcoal wafers are very thin. The front fine-
mesh stainless steel screen is inserted into the channel
support. Typically, three 40 mm square wafers of the
charcoal cloth are laid over the front fine mesh screen
in the channel support, followed by a large mesh backup
screen. A thin square inner shim assembly is then
inserted over the large~mesh back screen to retain the
sorbent assembly in place. Alternatively, a two-leafed
., . . :
.
-
.~ `
.
, ,.. , . . . .. . - . :
WO90/09572 ~ PCT/US90/00584
~ ...................................... . .
. .
- 31 -
spring-loaded thin inner shim assembly may be used for
this purpose; the two legs axe compressed then inserted
and allowed to expand to seal the bed in place.
One possible sampling configuration ~ould
involve three sample containers of the type described by
Figure 17 where the sample canister would contain front,
middle and back sorbent sections of charcoal cIoth wafers
or wafers of other sorbent material. This arrangement
finds use for high-vapor pressure analytes that migrate
from one sorbent section to the next during storage
because it permits the individual sorbent sections to be
separated from one another immediately after sampling.
Alternatively, it permits spacers such as thin 40 mm
square sheets of stainless steel to be inserted between
the three sorbent sections to minimize such migration.
Another obvious configuration is assembled as above
except that the entire sorbent bed is placed in a triple-
depth channel support. First, the front fine mesh
retainer screen is inserted, followed by the front char-
coal cloth sorbent bed, a large mesh spacer screen, the
middle charcoal cloth b~d, another large-mesh spacer
screen, and finally the backup charcoal cloth bed
followed by the back large mesh screen, followed by the
retainer clip.
Another variation on the sampler configuration
is one which permits estimation of the total amount of
analyte received by the subject. This is shown by Figura
18 which lacks a filter to remove the analyte from the
ambient air and is specifically designed to be used in an
area of contaminated air. The contaminated air is
inhaled through an inhalation check valve and exhaled
through a canister of sorbent. To ensure that all the
exhaled air and none of the inhaled or ambient air passes
through the sorbent canister, at least one and preferably
two check valves, one on each side of the canister are
added. The conduit leading from the mouthpiece may also
optionally have an access port for sampling the air or
,
~ : , ' ', ` '
WO90/09;72 PCT/US90/005B~
?.. ~ 32 - !
replacing the inlet check valYe(s).
The dose a subject receives can he calculated
by measuring the total volume inhaled multiplied by the
analyte concentration aP.d the percent absor~ed by the
subject. The percentage absorbed can easily be calcu
lated from the amount measured in the canister. From the
does absorbed per breath one can thPn determine the total
dose absorbed by the subject and act accordingly. Air
concentrations of various analytes are fair measures of
one's exposure to gasses and ~olatile chemicals but they
do not indicate the actual amount received. In accord-
ance with the invention one finally has an easy/ unobtru-
sive, and readily repeatable technique on demand to
determine the estimated amount the body actually
absorbed.
Figure 19 shows a single sorbent retainer ring
that may replace part 404. The retainer may fit into the
sample canister 412. At the bottom, it engages the rear
retainer screen 406 and at the top it engages the Teflon
washer 402 in Figure 4. Along with the torous, the
retainer ring may have a cutout to engage an anti-
rotational lus in the sample canister. The system may
use any particular sorbent or combination of sorbents.
The foregoing description of the specific
embodiments will so fully reveal the general nature of
the invention that others can, by applying current ~now-
ledge, readily modify and/or adapt for various applica-
tions such specific embodiments without departing from
the generic concept, and, therefore, such adaptations and
modi.fications should and are intended to be comprehended
within the meaning and range of equivalents of the dis-
closed embodiments. It is to be understood that the
phraseology or terminology employed herein is for the
purpose of description and not of limitation.
. .
