WO2008056117A1

WO2008056117A1 - Detection system apparatus

Info

Publication number: WO2008056117A1
Application number: PCT/GB2007/004211
Authority: WO
Inventors: James Gordon Campbell; Robin Touquet
Original assignee: James Gordon Campbell; Robin Touquet
Priority date: 2006-11-08
Filing date: 2007-11-05
Publication date: 2008-05-15
Also published as: GB0622212D0; EP2126108A1

Abstract

A test apparatus for alcohol, the apparatus comprising a matrix having an observation zone subject to a colour change dependent upon the presence of alcohol, the observation zone having an embedded reactant to alcohol to provide the colour change and the matrix arranged to regulate presentation of a test liquid to the observation zone.

Description

DETECTION SYSTEM APPARATUS

FIELD OF INVENTION

The present invention relates to a diagnostic device for testing blood to determine the concentration of blood ethyl alcohol.

BACKGROUND TO THE INVENTION

Alcohol is the most common drug of abuse and it is employed almost universally worldwide recreationally, frequently to excess and it is often abused and consumed in quantities that cause inebriation, intoxication, and loss of control. It is frequently associated with injuries requiring a hospital visit.

Over fourteen million people a year are treated in emergency departments (EDs) in England. In view of the strong association between alcohol misuse and health related problems such as accidental injury and violence, it is not surprising that alcohol misuse is greatly more prevalent among people attending EDs than among the general population. As many as one in three attendees have consumed alcohol immediately before their presentation, and more than two thirds of attendances after midnight may be alcohol related (2).

It is established practice in some EDs to routinely carry out blood alcohol levels, using laboratory methods. However because of not having the facility for 'near patient testing' this takes more than one hour due to the logistics of returning the result to the requesting department; even if it is transmitted by placing the result on the hospital chemical pathology computer screen for the acute physician to read. It has also been found there is a 'teachable moment' immediately following admission to ED where there is a good opportunity to offer patients brief advice concerning their alcohol misuse.

A raised blood alcohol level is definitive proof of a patient's vulnerability both in immediate management, e.g. of the airway, but also later; for identifying the dependent drinker with diminished immunity and prolonged healing rates; chronic alcohol misuse affects every body system and organ. In treating the patient's current injuries or symptoms it is possible the opportunity of using the Teachable Moment' to effect change will be lost particularly if test confirmation of an alcohol related issue is delayed. 'Clinical Inertia' is a problem, for it is all too easy for staff to forget to later ask about alcohol misuse when the patient has recovered sufficiently to be on the hospital ward.

In addition to delays patients and doctors may feel certain sensitivity about requesting blood alcohol levels because of judicial considerations. There is however clearly a need to consider medico-legal implications of alcohol determinations.

In the Emergency Department a blood alcohol level has been shown to be of help in the initial assessment and management of a patient.

Advanced Trauma Life Support (ATLS) training, states that patient's blood should be sent for tests for alcohol levels. However, testing delays of over an hour mean acute intoxication alters the initial assessment of injury severity, resulting in an increased use of both invasive diagnostic procedures (diagnostic peritoneal lavage, CT head scanning, intracranial pressure monitoring) and therapeutic procedures (tracheal intubation, tube thoracostomy). A further problem relates to the dependent drinker who has developed tolerance and so may appear sober. Therefore accurate clinical assessment of the blood level of alcohol has hitherto been neither easy nor accurate. The periodicity from when, and over what time, the ED presenting patient drank alcohol, its rate of absorption and how quickly the alcohol is metabolised are all very variable. However in the immediacy of presentation to the ED it would be logistically easiest to immediately obtain the blood alcohol by near patient testing.

There is a desirability for testing individuals to determine the extent to which they are under the influence of alcohol. Alcohol use in most countries is legal, and supply of alcohol is widely available. In other countries where alcohol consumption is prohibited it nevertheless can be consumed illicitly and may still represent a problem to the medical profession.

Many people develop alcohol dependence and tolerance, resulting in a significant proportion of the population having a problem with alcohol intoxication at some time or other. It is therefore highly desirable to test for the level of alcohol intoxication and so this has been the subject of many studies hitherto.

There are many schemes for testing an individual to determine their intoxication from alcohol and they range from physical tests such as requiring them to walk in a straight line, and touching their nose with their eyes shut, to various designs of breathalyzer and alcometer and even more sophisticated laboratory techniques requiring accurately measured reagents and body fluid samples.

Physical tests require the participant to be mobile and willing, and are usually restricted to police checks to judge fitness for driving or other duties; breathalysers and alcometers require the participant to be cooperative, and laboratory techniques require sophisticated non-portable machinery and facilities. These methods are generally unsuitable for Emergency Departments because they either require active participation from the subject although they are probably incapacitated through intoxication or injury, or else the methods take too long for a result to be meaningful or incorporated into the treatment given.

Test strips or sticks are also available which are immersed in a sample of urine or saliva, and which include an indicator which changes colour in response to the presence of alcohol and these are well known. These test strips and sticks include, for example, litmus or other indicator papers for determining the pH of solutions, as well as sophisticated test devices for detecting clinically significant substances in biological fluids. Examples include glucose or protein in blood or urine samples, ketone in urine, and alcohol in saliva.

A comprehensive discussion of test strips covering both their chemistry and also techniques of manufacture and use may be found for example in U.S. Pat. Nos. 4,361 ,648 and 4,362,697. These patented schemes are concerned with testing a wide variety of body fluids for cholesterol, glucose and others, and include the suggestion of peroxidase and peroxidase-like substances as catalysts in promoting the colour change reaction on an indicator. Many of the techniques disclosed in these patents are limited to laboratory environments and require complicated instruments or complex calibration systems. Illustrative of rapid test techniques is U.S. Pat. No. US2003232321 wherein a test strip is treated to detect glucose in blood in a finger prick format.

In accordance with aspects of the present invention there is provided an apparatus for detecting alcohol, the apparatus consisting of an impregnated material which produces a reaction resulting in a colour change in an observation zone in the presence of alcohol, with detection capability of less than 0.02% alcohol and greater than 0.5% such that the level of intoxication may be determined without the addition of any other reactant to a reaction zone other than those in the device and a liquid such as blood to be tested.

Also in accordance with the present invention there is provided a test apparatus for alcohol, the apparatus comprising a matrix having an observation zone subject to a colour change dependent upon the presence of alcohol, the observation zone having an embedded reactant to alcohol to provide the colour change and the matrix arranged to regulate presentation of a test liquid to the observation zone.

Typically, the embedded reactant comprises an alcohol oxidase and tetramethyl benzidine.

Generally, the matrix incorporates a membrane. Possibly, the membrane comprises a fibreglass and/or non porous material. Typically, the membrane incorporates cellulous fibres and/or fine fibreglass fibres. Possibly, the membrane acts as filter.

Generally, the matrix is supported by a fibre based card or plastic substrate or high density polystyrene substrate in order to support the matrix in use.

Typically, the matrix is designed to receive the test liquid in order to deliver a regulated rate of test liquid to the observation zone for reaction with the embedded reactant. Alternatively, the matrix is arranged to present the test liquid by separation of a proportion of the test liquid for reaction with the embedded reactant. Possibly, the test liquid comprises blood. Typically, where the test liquid is blood, the matrix is arranged to act as a filter for the blood to present substantially only plasma to the observation zone.

Generally, the embedded reactant gives a colour change visible to the naked eye. Possibly, the observation zone may be associated with an automatic reader device to determine the extent of colour change indicative of the proportion of alcohol within the test liquid.

Possibly, the colour change occurs in the range 450 - 510 nano metres.

Possibly, the matrix has an opaque or low reflectivity backing.

Embodiments of aspects of the present invention will now be described by way of example and with reference to the accompanying drawings in which:-

. FIG. 1 shows a schematic arrangement of an embodiment of the test device.

FIG. 2 shows a schematic arrangement of a second embodiment of the test device.

FIG. 3 shows a schematic arrangement of a third embodiment of the test device.

Previously, rapid alcohol testing has most conveniently been carried out by using breath alcohol or saliva alcohol although these methods are not ideal. Nevertheless the relationship between blood alcohol, breath alcohol and saliva alcohol have been researched extensively in order that legal actions may be taken based on the results from each of these media. Results from saliva, breath or urine are frequently converted to a blood alcohol level and there are various correlation factors to allow the authorities to switch between the different biological media of urine, blood, saliva and breath. Most particularly it is widely held that the relationship between saliva alcohol and blood alcohol is a ratio of 1.1 to 1 under equilibrium conditions. Notwithstanding that alcohol is usually determined with breath or saliva and converted to blood, nevertheless the 'gold standard¹ for alcohol determination is blood alcohol and this medium is widely utilized for the prosecution of drivers under the influence of alcohol, in which case analysis is carried out by sophisticated gas chromatography. The blood sample is a venous sample and invariably is obtained by a medical practitioner and is subject to strict chain of custody regulations. This approach is cumbersome and involves a time delay along with patient resistance in view of the legal consequences. A rapid broadly indicative test would be beneficial in order to take advantage of the 'teaching' moments.

Blood alcohol determination as described by the present invention requires the following steps.

Alcohol oxidase procured from suppliers such as Sigma Aldrich is dissolved in water with a suitable buffer such as sodium phosphate giving around pH 7 and peroxidase with a wetting agent such as Glyceryl laurate is used to soak cellulose membrane which is then allowed to dry. A second solution of tetramethylbenzidine procured from suppliers such as Sigma Adrich dissolved in an organic solvent such as methyl chloride or xylene (m- dimethylbenzene) at around 15mg/ml is prepared and the paper is dipped into this solution and allowed to dry. This membrane is incorporated into a test strip as described elsewhere.

In order to carry out a blood alcohol test, a small quantity of blood, preferably a finger-prick sample of blood consisting of one drop is produced preferably by a small fingertip lancet device capable of painlessly piercing the skin and indeed this system is widely adopted routinely in hospitals using proprietary devices not included in this patent application.

Preferably the alcohol test device is a carrier housing the reaction membrane as a matrix which holds the enzymatic chemistry previously described on which preferably separation of the erythrocytes (red blood cells) from the plasma occurs, and colorimetric enzymatic chemistry reacts to form a coloured product which is read by the opto-electronic instrumentation or crudely by the naked eye.

The detection system comprises a test paper, strip or bibulous member or tube or other element carrying the technology for detecting blood alcohol, suitable for use on its own and read visually or used with a reader consisting of an opto-electronic measuring and preferably data logging system. The identification system is suitable for use in all circumstances where the detection of blood alcohol is desirable or necessary, having a detection level suitable for detection of alcohol at all typical levels in human whole blood. It is also suitable for detecting alcohol in other bodily fluids for example plasma, serum or saliva and in foodstuffs and liquids.

For convenience the apparatus may be, but is not restricted to, application via a number of embodiments such as a strip element dipped into the solution or the solution may be applied to the element from a finger prick system or using a dropper, or the elements may be contained within a casing, cassette or apparatus, or sandwich of membranes serving a similar function.

The present invention optionally includes a facility to simultaneously or sequentially detect blood alcohol and blood glucose on the same sample.

Furthermore, the accuracy to the present alcohol determination is proportional to the concentration, and whilst the present method will be highly reliable at zero concentration, (it is important to determine if a patient has been drinking at all recently) accuracy will be within about 5% for levels above 10mgs% making the procedure unsuitable for judicial considerations. The test acts as an indicator to medical treatments and determination as well as with regard to the 'teach' moment as discussed above.

Blood alcohol determination as described by the present invention requires alcohol oxidase which is available from many suppliers (e.g. Sigma Aldrich) and tetramethylbenzidine (also available from Sigma Aldrich) impregnated onto a matrix membrane in the form of a sandwich. The oxidation of tetramethyl benzidine yields a component with an absorbance maximum at 450 nm.

Indeed a wide variety of body fluids may be assayed for various substances including cholesterol, glucose and ethanol content. In the present tester ethanol is detected by one of several existing proprietary systems. One such method utilizes a system whereby alcohol is transformed into acetaldehyde by the action of alcohol dehydrogenase or oxidase, with this reaction, in turn, reducing an NAD indicator to its NADH form. However the extent of the reaction is determined by ultraviolet colorimetry providing the ultimate indication of alcohol content in the body fluid tested. Such an arrangement, while well suited to laboratory conditions, is poorly suited to the determining of the alcohol content of an emergency room admission because it is too time consuming for the results to be of value.

Alcohol oxidase is an enzyme also found in the human liver where it functions to catalyze the oxidation of alcohol in the same-reaction employed in the current patent. This enzyme is also employed in substantially the same way in the scheme disclosed in U.S. Pat. No. 3,493,467 but this patented arrangement is rather complex and is limited to a laboratory environment.

Alcohol oxidase is available from many suppliers (e.g. Sigma Aldrich) and the reaction to produce a coloured substrate reaction is commonly known and forms one of the routine tests carried out in pathology. In this reaction alcohol is oxidized to acetaldehyde (ethanal) and hydrogen peroxide which is used to react with a chromochemical such as tetramethylbenzidine (Sigma Aldrich). The two electron oxidation of tetramethylbenzidine yields a component with an absorbance maximum at around 450 nm.

While this reaction type is common knowledge, and reagents are widely available from sources known to those knowledgeable in the art, hitherto each of the aforementioned systems have been limited to applications for alcohol testing with a sample of saliva. However we have shown there are sound clinical arguments why saliva is of little use to the clinician in a hospital environment in determining the alcohol level of a patient who is though to be under the influence of alcohol.

Recent drinking, most particularly in the intervening period of some fifteen minutes from the time the patient was drinking alcohol to the time the patient is admitted to accident and emergency will produce abnormally high levels of salivary alcohol compared to the quantity of alcohol in his or her body. Conversely if the patient has consumed abnormally high levels of alcohol (such as is the current trend in Britain for binge drinking) potentially vast quantities of alcohol will reside in the stomach still to be absorbed but the salivary alcohol will be abnormally and dangerously underestimated because the doctor in attendance will be unaware of the danger to the patient that is to follow. Simple saliva alcohol test strips are of little value here because they have a poor colour response, frequently have to be read in less than favourable lighting conditions and cannot give the sensitivity required to measure rising alcohol levels that may be inferred, but with no way of verifying by a doctor under the constraints of an accident and emergency situation.

Even worse, laboratory tests for alcohol content of blood take time and are of little value in dealing with a patient whose needs may well be immediate.

Alcohol levels may also be detected using urine but this system of analysis requires complicated laboratory instruments and there is questionable value in using urine for this purpose because urine entering the bladder has an ever-reducing level of alcohol and each voiding of the bladder represents an average value of alcohol from the time of the previous voiding to the time of the current voiding but these times are rarely noted.

Hitherto it has not been appreciated by those practiced in the art that blood alcohol concentrations are required at the point of admission for such people. Doctors and nurses are well practiced in the art of obtaining blood from a finger prick test site, or by venous or intramuscular sampling of blood and this is done routinely at hospital for a wide range of tests and screens such as hepatitis, HIV, blood glucose monitoring and the like.

Absolute accuracy of blood alcohol level result is not necessary and in any case is a futile activity because the blood level will not be steady state and will either be decreasing (because the patient is metabolizing previous drinking episodes) or else increasing (because the donor is absorbing recently consumed alcohol from the gut). It will be appreciated by those experienced in the art that neither of these situations will yield a satisfactory saliva alcohol reading. What is more essential is a rapid system for detecting the approximate alcohol level in a blood sample with a reasonable test-to-test reproducibility for that particular batch of test device. This is because blood alcohol correlates accurately with the effect of alcohol on the brain and hence on the limbic system and neurological functions.

What is more essential is a rapid system for detecting the approximate alcohol level in a blood sample with a reasonable test accuracy, and to test reproducibility for that particular batch of test devices so that a patient's progress may be monitored reliably.

It has been discovered that far from high accuracy being futile because blood alcohol levels are dynamic, high accuracy is also detrimental because some individuals will refuse a blood alcohol test in view of its historical medico-legal associations with police action against motorists and operators of machinery, and the like if it is admissible as evidence. It is realize that having a system that is not admissible as evidence because the standard deviation of the results is too high is an advantage in administering the test precisely because there is no risk of police action after the event. The proposed device has a high accuracy at alcohol values close to zero and this reduces to around 5% at 10mgs% and this is ideal for the intended purpose of the instrument, however the instrument has capability of all levels of accuracy and all levels are covered by this patent.

In one embodiment of the test shown in Figure 1 , carrier (2) made from a suitable substrate such as fibre based card, plastic such as PVC or high density polystyrene, supports a matrix membrane (14) made from fibreglass or other non-porous material, which is co-joined onto membrane (22) consisting of cellulose or fine glass fibre suitable for retaining and filtering out red blood cells so that substantially only plasma is transferred by capillary action onto the membrane pad (31) on which it is co-joined for observation.

The reaction pad (31) is made from nitrocellulose or similar bibulous material and houses a reaction zone (34) of alcohol oxidase and tetramethylbenzidine in the manner utilised by, for example, Aeon laboratories et al, 4108 Sorrento

Valley Boulevard, San Diego, CA 92121 , USA, and suitable for generating a reaction with alcohol; any excess fluid travelling to absorbent felt pad (42) which acts as a sink for such fluid. This reaction zone (34) is also an observation zone viewed to provide an indication of alcohol level by a noticeable colour change.

In use this embodiment has the following purpose. A blood sample such as that from a finger prick is placed at some point on the fibreglass membrane (14) and the blood sample travels along the pad by capillary action by virtue of the fact that fibreglass has numerous fibres that aid capillary action whilst at the same time having little capacity to soak up and absorb the blood, thereby providing maximum volume for the reaction to take place with the minimum of blood. The fibreglass membrane is co-joined to membrane (22) having the capacity to filter out red blood cells and allowing plasma only to spill over by capillary action onto the co-joined reaction membrane (31) containing reactive medium for detecting the concentration of alcohol. Excess plasma that is available from the sample may be absorbed in the co-joined pad (42). After a suitable reaction time, for example 2 minutes after the blood has reached the reactive zone, the test strip may be read visually for blood alcohol content or else the strip may be placed in an automatic reader such as the SureScreen Reader available from SureScreen Diagnostics Ltd, 1 Prime Parkway, Derby DE1 3QB England. This reader displays the result of blood alcohol from scanning and establishing the density of the colorimetric reaction on the treated reaction zone of the test strip, preferably reading the degree of reaction at around 450 - 510 nm wavelength.

In a second embodiment of the test shown in Figure 2, the membranes may be placed in a sandwich array as follows. Inert mask (24) made from printed plastic perforated to allow the blood sample to pass and optionally carrying instructions or arrows showing the correct way to insert the test in a reader, is attached to optional membrane (15) made from material such as fibreglass or coarse nitrocellulose carrier designed to transfer a spot of blood from a finger prick through to membrane (18) consisting of cellulose or fine glass fibre suitable for retaining and filtering out red blood cells so that plasma is transferred by capillary action onto the membrane pad (16) made from nitrocellulose or similar bibulous material housing a reaction zone (21) of alcohol oxidase and tetramethylbenzidine in the manner utilised by Aeon laboratories et al. and suitable for generating a reaction with alcohol; all supported by a carrier such as PVC or high density polyethylene with a perforation suitable for the result of the test to be read from below through the perforation, and preferably backed by a black or low-reflectivity coating on a strip applied to the back of the carrier for the purpose of reducing the reflectance of the carrier onto the reading device in order to optimise the result in an automatic reader.

In a third embodiment the sandwich may be modified such that red blood cells are not filtered out but are incorporated into the liquid being tested, in which membrane (18) may be optionally omitted, the result then consisting of a colour change notwithstanding the masking presence of red cells which nevertheless produces a result suitable for an optoelectronic detection device to read the result.

The second and third embodiments described above are suitable for insertion into a reading device consisting of a light emitting diode or similar preferably operating at wavelengths between 450 and 510 nm and an optoelectronic detection device such as a charge coupled camera, light detection diode or other suitable detector capable of reading absorbance under these same lighting conditions in order to produce an automated reading of blood alcohol.

Preferably the reader has a liquid crystal display to enable the user to read the results, a meter sensor area and a battery compartment. Preferably the meter has an on-off button, a memory recall button to recall previous results and a code adjustment button for calibration which may act as a function button for other operations. Preferably the meter will incorporate a data port for the results to be downloaded. Preferably the meter will have a Bluetooth function to automatically download the results to the patient's records or a central database. Preferably the meter is set up using a control solution having a known concentration of alcohol in a suitable solution, which preferably is coloured. Preferably the meter produces a result from one drop of blood produced by a finger prick test using a lancet.

In further embodiments the respective components may be arranged in other formats suitable for automated instrumentation such as tubes, panels with other tests, and the like. The detection system may for example comprise a test paper, strip or bibulous member or tube or other element.

The proposed device application is not restricted to blood from an ED or RR admissions patient and it may for example be applied to living or dead patients, to finger prick or whole bulk blood, serum or plasma, from medical patients, alcohol units, or home applications for monitoring of alcohol abuse, or for various other applications such as monitoring of the performance of personnel working in hazardous environments, for example. The scope of application of the device includes any application where alcohol detection is desirable including the screening of foodstuffs for contamination, whereby for example yeast attack of fruit or fruit extracts could be detected by the onset of fermentation of alcohols; nor is the invention limited to the aforementioned applications.

As described in the second and third embodiments and further embodiments that are suitable for automatic reading, in a fourth embodiment blood alcohol tests are incorporated together with glucose monitoring by the use of multiple chemistries or else separate reaction areas on the same embodiment, whereby blood alcohol level may be read at any suitable wavelength such as 450 - 510 nm and blood glucose may be read at an appropriate wavelength such as 560 nm.

By way of example, the present invention may be advantageous because blood alcohol accurately represents the state of the patient because it is free from the disadvantages of saliva, breath or urine which can be vastly different from the level of alcohol in the brain and other organs for reasons discussed previously.

By way of further example the present invention may be advantageous because the level of blood alcohol will be obtained from any patient whether conscious, incapacitated, comatose, injured, cooperative or non co-operative via a simple finger prick blood sample.

By way of further example, the present invention may be advantageous because the medical profession prefer to rely on blood alcohol levels over any other medium such as breath or saliva because blood alcohol relates directly to the effects of alcohol on the brain and other organs.

By way of further example, the present invention may be advantageous because the medical profession routinely obtain and handle blood samples for a range of other medical tests and are conversant and readily prepared in their areas such as Ed's for the taking and handling of blood samples.

By way of further example, the present invention may be advantageous because the quantity of blood required is very small being typically one drop, and this quantity is readily obtained by a number of medical lancet devices already used routinely in healthcare, such devices requiring little or no training and virtually painless in use.

By way of further example, the present invention may be advantageous because blood alcohol measurements can easily be repeated from time to time as necessary to monitor alcohol levels and avoid the risk of alcohol poisoning from alcohol still remaining in the stomach of an incapacitated patient.

By way of further example, the present invention may be advantageous because the test device will also detect the simpler homologue methanol (from methylated spirit) which is toxic and which is often implicated in alcoholics living on the street who frequently require medical attention in ED's.

By way of further example, the present invention may be advantageous because the blood alcohol level may be incorporated into other devices separately or simultaneously.

By way of further example, the present invention allows the simultaneous analysis of blood alcohol and blood glucose in one operation and one machine to the benefit of the clinician and the patient. Thus, the reagents and matrix configured to provide the desired colour changes necessary for each analysis as noted by the naked eye are provided in one test assembly or a machine reader for both tests provided so that the results are given together for convenience. By way of further example, the present invention may be advantageous because the system is suitable for reading in an automatic reader which provides results from illumination at 450-510 nm which optimises the accuracy of the result.

By way of further example, the present invention may be advantageous because the blood alcohol result is achieved in such a way that it is unlikely to be admissible as evidence, thus preventing patients from refusing a test in case they are subjected to legal action.

By way of further example, the simultaneous analysis of blood alcohol and blood glucose in one operation may be advantageous because these results are both important and provide complementary information for the clinician in cases where hypoglycaemic symptoms can closely mimic those of someone who is inebriated or in cases where it is known that alcohol can trigger dangerously serious hypoglycaemia in those people who are susceptible, and this information determined at the same time is to the benefit of the clinician and the patient in providing treatment in the shortest timescale.

The present device may be used in other areas and other hospital disciplines, e.g. Gastro-enterology (including Hepatology), or for its use in General Practice or by Addiction services. The immediacy of near patient testing - facilitated by using the proposed device - will enable the practitioner to better manage their patients, as well as making practitioners more 'alcohol aware¹ so as to get their patients to contemplate change if alcohol levels are found to be high. With verbal consent from the alert and orientated patient, the patient is taking part in the process of assessing their own blood alcohol concentrations. This will further the reality to the patient that alcohol is a drug - not just a social lubricant - and therefore provide the opportunity for excessive drinking or episodes of binge drinking - to be discussed in real time without having to wait for a laboratory test result.

Claims

1. A test apparatus for alcohol, the apparatus comprising a matrix having an observation zone subject to a colour change dependent upon the presence of alcohol, the observation zone having a unitary embedded reactant to alcohol to provide the colour change and the matrix arranged to regulate presentation of a test liquid to the observation zone.

2. An apparatus as claimed in claim 1 wherein the unitary embedded reactant comprises an alcohol oxidase and tetramethyl benzidine.

3. An apparatus as claimed in claim 1 or claim 2 wherein the matrix incorporates a membrane.

4. An apparatus as claimed in claim 3 wherein the membrane comprises a fibreglass and/or non porous material.

5. An apparatus as claimed in claim 3 or claim 4 wherein the membrane incorporates cellulous fibres and/or fine fibreglass fibres.

6. An apparatus as claimed in any of claims 3 to 5 wherein the membrane acts as filter.

7. An apparatus as claimed in any preceding claim wherein the matrix is supported by a fibre based card or plastic substrate or high density polystyrene substrate in order to support the matrix in use.

8. An apparatus as claimed in any preceding claim wherein the matrix is designed to receive the test liquid in order to deliver a regulated rate of test liquid to the observation zone for reaction with the unitary embedded reactant.

9. An apparatus as claimed in any preceding claim wherein the matrix is arranged to present the test liquid by separation of a proportion of the test

^' liquid for reaction with the unitary embedded reactant.

10. An apparatus as claimed in claim 9 wherein Possibly, the test liquid comprises blood.

1 1. An apparatus as claimed in claim 10 wherein where the test liquid is blood, the matrix is arranged to act as a filter for the blood to present substantially only plasma to the observation zone.

12. An apparatus as claimed in any preceding claim wherein the unitary embedded reactant gives a colour change visible to the naked eye.

13. An apparatus as claimed in any preceding claim wherein the observation zone may be associated with an automatic reader device to determine the extent of colour change indicative of the proportion of alcohol within the test liquid.

14. An apparatus as claimed in any preceding claim wherein the colour change occurs in the range 450 - 510 nano metres.

15. An apparatus as claimed in any preceding claim wherein the matrix has an opaque or low reflectivity backing.

16. Apparatus for detecting alcohol, the apparatus consisting of impregnated material which produces a reaction resulting in a colour change in an observation zone in the presence of alcohol, with detection capability of less than 0.02% alcohol and greater than 0.5% such that level of intoxication may be determined without the addition of any other reactants to the reaction zone other than those in the device and the blood or liquid being tested.

17. The device according to claim 1, wherein the concentration of the blood alcohol in the blood sample is read by an opto-electronic device and produced as a direct readout of concentration.

18. An apparatus for detecting alcohol substantially seen as hereinbefore described as reference to the accompanying drawings.

19. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.