Title: BREATH ALCOHOL STORAGE CONTAINER AND METHOD OF USING SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to equipment for breath analysis, and particularly to storage means for alcohol and other organic substances in breath samples.
It is well known, according to Henry's Law, that there is a relationship between alcohol occurring in last phase expired breath and blood alcohol content. A one part per thousand concentration of blood alcohol corresponds to 1 mcr. of ethyl alcohol per cσ. of blood, and leads to an alcohol content of approximately 1 mg. in 2100 σσ. of exhaled breath. The knowledge of this relationship has led to widespread use of last-phase breath samples for quantitative alcohol analysis, particularly in connection with traffic law enforcement.
The need for storage means for alcohol and other organic substances in breath samples has become exigent. A breath analysis conducted at roadside may not be conducted properly or under properly controlled conditions, and the results may thus be vulnerable to attack from an evidentiary viewpoint in a court of law. Some jurisdictions and courts now require a second analysis of the breath, in addition to the first one, before the evidence can be relied on in court. Breath alcohol storage devices permit subsequent testing under controlled laboratory conditions, or preservation for evidentiary purposes.
There are two main aspects to the development of a suitable storage container, namely the finding of a suitable alcohol-retaining compound and the adoption of a suitable container for the compound.
The ideal storage compound should sorb the alcohol readily, and should retain it until its release is intentionally triggered, at which time it should release the alcohol readily and completely. It should not be too deliquescent, since the presence of moisiure in the breath may cause the material to become caked within the container and thus may clog it.
Generally speaking, since suitable storage compounds are desiccants or dehydrants, they must be dry initially and they must be kept dry, both before and after taking the breath sample. Not only does moisture sorbed by the compounds prior to taking the sample affect their ability to sorb alcohol, but also moisture sorbed after taking the samaple can cause part of the alcohol to be released prematurely. The compounds must therefore be kept in sealed containers.
A desireable feature, important from an eviden¬ tiary viewpoint, is that the container should be provided with some method of identifying the individual giving the sample. Another highly desireable feature is having some means of identifying whether or not any given container has already been used, i.e. whether or not it already contains a sample.
For convenience, the word "alcohol" will be used throughout this specification as denoting ethanol and other substances which are to be stored, including other vapours occurring in breath samples, such as acetone, methanol, isopropanol, etc.. In conducting breath analysis, one is primarily interested in the level of ethanol, but also in methanol, which may be present due to the ingestion of cheap
or contaminated spirits, and in acetone, which may be present in the breath of diabetics or dieters.
2. Description of the Prior Art
Breath alcohol storage containers in the prior art generally either use indium bags or comprise an alcohol retaining compound held in a container, the container having openings at opposite ends to permit the breath sample to be flowed through it. An example is the container described in United States patent number 4,080,170 granted to Borkenstein on March 21, 1978, which will be discussed in more detail later herein..
Since the discovery in the 1930s that anhydrous magnesium perchlorate had the property of absorbing certain organic vapours, including alcohol, various compounds have been used for storage to permit subsequent reliable quantitative analysis. Other previously used compounds include calcium carbonate, calcium chloride, magnesium sulphate, sodium sulphate, silica gel, and calcium sulphate, as well as a so-called "molecular sieve", which is a composite of several anhydrous substances.
Some of the presently-used storage compounds are not entirely satisfactory. Silica gel, for example, is highly absorptive, and special methods must be applied to produce the release of the retained alcohol. Calcium chloride is more appropriate for the purpose, but it is still quite deliquescent.
In the prior art, the containers for the compounds are stored, both before and after taking the sample, in second containers, these second containers being sealable. Alternatively, the compound containers themselves are plugged or capped in some fashion before and after the sample is taken, the plugs or caps being removed at the time of taking the sample. In other cases, a glass seal has to
be broken before taking the sample, and the ends capped afterwards. In either case, a certain amount of handling is inevitably required, and care must be taken to ensure that the compound is not exposed to the environment, always containing moisture, for any appreciable length of time. All too frequently, caps come off, leaving the compound exposed to air.
The container described in the previously- mentioned Borkenstein patent provides an example. The container consists of a glass tube with openings at each end, the tube containing calcium sulphate as the alcohol- retaining compound. These containers are assembled in a warm oven to ensure that the calcium sulphate is anhydrous, and they are placed in a second container with a screw top. When a breath sample has to be taken, the container is taken out of the second container, the necessary connections are made, and the breath sample is flowed through. After that, the container is disconnected from the system, and is put back into the second container, which is then closed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide improved storage containers for alcohol and other organic substances in breath samples.
Accordingly, in the present invention there is provided an improved breath alcohol storage container with openings at opposite ends thereof, and an alcohol-storing compound retained within the container. In the preferred embodiment, the alcohol storing compound is mainly l20, and seals extend across the openings at each end of the container, the seals comprising a resilient membrane adapted for non-unsealing penetration by a hypodermic needle.
In accordance with another aspect of the invention, there is provided within the container a
moisture-sensitive compound which changes color in response to the moisture in a breath sample, thereby indicating when the container has been used.
In accordance with yet another feature of the in¬ vention, there may be optionally provided on the outside of the container a waxed surface for receiving the thumb or finger print of the individual whose breath is being sampled, along with means for protecting said waxed surface, whereby positive identification of the sample is achieved.
Additional features of the invention will become apparent in connection with the description of the preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment of the present invention will now be described in detail, with reference to the accompanying drawings, in which:
Figure 1 is a schematic drawing of a typical breath sampling system;
Figure 2 is a drawing of the container of the present invention;
Figure 3 is an end view of the container of the present invention; and
Figure 4 is a detailed sectional drawing showing sealing caps on the ends of the container.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to Figure 1 , a conventional breath sampling system is shown schematically. The test subject provides a breath sample by exhaling through the mouthpiece
1 into the breath chamber 2, valve 3 being open and valve 4 being closed. The breath chamber contains a piston β and overflow openings 7 so that it is the last phase of exhaled breath which is captured. Valve 3 is then closed, valve 4 is opened, and the plunger 5 is pressed, causing the piston 6 to force the breath sample through valve 4, and in the case of the present invention, through a hypodermic needle 30 to the sample storage container 10, air in the sample storage container being expelled through the ventilating hypodermic needle 31.
It will of course be appreciated that the schematic diagram is provided for purposes of clarity only, and that the invention is not restricted to any particular breath sample collection system.
Referring to Figures 2, 3 and 4, the storage container itself will now be described.
The storage container 10 comprises a glass, plastic, or metal tube 12, with openings at each end. Across each opening, i.e- across the ends of the tube, are sealing caps 15. In the container is a quantity of Al2°3 n granular form, with a grain size of approximately 30 to 50 mesh. The l2°3 is identified in Figure 2 by the reference numeral 13. This aluminum oxide is a known desiσcant, but nevertheless its particular suitability for this application appears to have been overlooked in the prior art. It has been discovered that it is particularly suitable as a storage compound in the present application. It is not too deliquescent, and thus remains in granular form within the container when exposed to moisture in a breath sample, and does not clog the container. It appears to adsorb the alcohol, as well as such substances as acetone, and releases them readily for analysis.
Also present in the container is a small quantity of crystals with a coating of cobalt chloride, CoC^r which responds to the moisture in a breath sample by turning from
blue to a shade of pink, thereby indicating whether or not the container has been exposed. This moisture indicating substance is identified in Figure 2 by the reference numeral 14. An indication can alternately be achieved by the use of indicator paper, either shaped to retain the storage compound in the tube (in the manner of the filter paper cups 16 in Figure 2), or in the shape of a longitudinal stripe running alongside the storage compound.
The container 10 must of course be transparent or nearly transparent to take advantage of this indicator feature.
The aluminum oxide 13 and the moisture indicator 14 are located centrally in the glass tube 12 between porous filter paper cups 16 which are wedged against the wall of the glass tube. The filter paper cups serve to retain the crystals or grains of aluminum oxide and cobalt chloride. They also serve to control the flow of the breath sample through the container, preventing excessive channeling of the breath through the aluminium oxide. Any other finely porous material would be suitable for such retainers.
Each sealing cap 15 comprises a silicon rubber membrane 20 with an inward-facing inert lining 21 of Teflon (trademark). The membrane covers the opening at the end of the glass tube. An aluminum crimp cap 22, provided with an aperture 23 aligned with the axis of the glass tube, secures the membrane across the end of the tube.
There is thus provided a seal which prevents moisture from entering the container. The container is assembled under relatively dry conditions, using dried compounds. The membrane 20 is resilient, and thus can be penetrated by a hypodermic needle without loss of the seal. The teflon lining 21 presents an inert surface to the interior of the container.
In making use of the container, then, a hypodermic
*•"-*"-• '-'
needle 30 is injected through the membrane 20 at one end of the container, this hypodermic being connected to the breath sample source as illustrated schematically in Figure 1. A second hypodermic needle 31 is injected through the membrane at the opposite end of the container, to provide an escape _ 5 path. The breath sample is then flowed through the container via the hypodermics, whereupon the moisture naturally present in the breath sample causes the indicator 14 to change color, and any alcohol or other volatile substances such as ketones or acetone prsent in the breath
10 sample are adsorbed, mainly in the aluminum oxide 13.
It is not important for the storage of the sample which direction through the container is chosen for the flow of the breath sample, but it is convenient to use the 1^ direction illustrated in Figure 2, namely the direction such that the breath sample flows first through the indicator substance 14 and then through the aluminum oxide 13.
Once the breath sample has been flowed through the
20 container, both hypodermics are removed, and the container remains sealed by virtue of the resilience of the membranes 20 in resealing the needle holes.
If required, the test subject, i.e. the sample *-*5 donor, is then asked to provide a thumb or finger print to positively identify the sample. The exterior of the glass tube 12 is provided with a lightly waxed segment 35, protected under a peel-back paper strip 36. The waxed segment is rolled along the subject's thumb or finger to t*-) make the imprint, and then the paper strip 36 is replaced. Adhesive bands 37 secure the edges of the paper strip to the glass tube.
The advantages of the sealing caps in the present ***> invention are several. The storage compound, in this case aluminum oxide, remains protected from the environment, not only before and after the flowing through of the sample, but
also continuously during the time surrounding the taking of the sample. This provides greater consistency and control over test conditions.
Also, the capping and uncapping steps are avoided, thus permitting easier handling procedures. The caps cannot be lost or fall off, which would render the collected sample invalid.
When the alcohol stored in the container of the present invention is to be tested, it is a simple matter to remove the seals at the end of the glass tube and to expel the contents of the tube for testing by any conventional means, such as gas chromatography for example.
It should be understood that the above description is by way of example only, as a number of variations can be readily envisioned by those skilled in the art, such obvious variations being within the scope and spirit of the invention whether or not expressly described and claimed.
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