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Highly accurate, low cost alcohol analysis . . . ALs AL sCOLYSER You’ve probably seen a few breath alcohol monitors in the past but this one is quite different – this simple system measures the amount of alcohol in the drink before it ever reaches your mouth (or stomach (or kidneys, or whatever!). It determines the percentage of alcohol in any drink with two very important parameters: high accuracy and low cost. Compare it with commercial units costing tens of thousands of dollars! by Allan Linton-Smith The components of Al’s Alcolyser: a Digitech Fuel Cell Alcohol Tester with supplied mouthpieces (Jaycar QM7302), a heated Travel Mug (Jaycar GH1301), an accurate thermometer (or a thermocouple and DMM), a caulking gun nozzle and some lengths of plastic tube. The 12V power supply at left is for the Travel Mug, while the Digitech electronic scale at rear (Jaycar QM7264) is for accurately weighing the alcoholic drink sample and water. 72  Silicon Chip ABOUT THAT NAME: Well, it is an alcohol analyser designed by Al . . . so what else would you call it? siliconchip.com.au N ot only is it easy to build, it works with all drinks (many analysers only work with specific drinks) and it also works over a very wide range – from no alcohol at all (0%) right through to nearly pure alcohol (95%). And it can even be used to calibrate one of those cheapie breath alcohol analysers as well, so you can be pretty much assured that when that is telling you you’re still under the limit, you ARE under the limit. One word of warning: if you do happen to earn the attention of the boys in blue, don’t try to use this as evidence in a court, because it won’t impress the magistrate one little bit. As they say in all good disclaimers, it’s for educational and/or entertainment purposes only and no responsibility for its use or consequences of its use will be accepted by the management . . . Having said that, if you’re accurate with your samples and temperature, the accuracy of this simple system will be right up there with the big boys! Introduction This unit uses fuel cell technology (see panel) to evaluate the alcohol content of drinks. Not only is it accurate but it is $0000’s cheaper than most alternatives. You might think there’s a zero or two too many there but that’s the amount of money you’d need to spend on a commercial equivalent (and then spend a fortune to keep it calibrated). Not only will it assist makers and consumers of wines, spirits, liqueurs, mixers, RTDs (ready-to-drink beverages) and cocktails, it may be used by those seeking to identify alcohol in beverages when it is not wanted! For example, we tested a “lemon, lime & bitters” (a commonly-ordered “non alcoholic” drink), bought over a bar, and this indicated that it contained over 1% alcohol (from the Angostura bitters, which contain 44.7% alcohol!). Our system is quick, easy and requires minimal training. Part of it uses a commonly available fuel-cell meter and a temperature-controlled travel mug (which heats the sample to the required temperature) while the rest is easy to build, requiring only a drill and a few pieces from your local hardware store! How do you measure alcohol? If you’ve ever dabbled with maksiliconchip.com.au BREATHE INTO HERE (ALCOHOL FREE BREATH!) MOUTHPIECE (ALL DIMENSIONS IN MILLIMETRES) THERMOMETER (OR THERMOCOUPLE AND DMM) EXIT TUBE ASSEMBLY GOES INTO HOLE AFTER THERMOMETER REMOVED 10mm PVC OR NEOPRENE FLEXIBLE TUBING 5mm DIAM x 150 LONG HEATSHRINK TUBING 165 105 BREATH TUBES (SUPPLIED WITH BREATH ANALYSER) 155 LIQUID UNDER TEST THIS END INSERTS INTO JAYCAR BREATH ANALYSER 5.0 THERMOSTATICALLY CONTROLLED TRAVEL MUG ing home brew, we can hear you saying “that’s easy, just use an alcohol hydrometer.” But it’s not quite that simple. Those instruments are perfectly good for beer and even wine and pure spirits. But what if you have to measure drinks which are a mixture of alcohol & sugars or juices – such as “mixers” (eg, a bourbon and cola), RTDs, ports, liqueurs and cocktails? Or what if you want to check the teenagers’ (theoretically non-alcoholic!) fruit punch that might have some – ahem – surreptitiously added “extras”? A hydrometer simply won’t work at all!! The problem is that sugars add to the density of a drink. A hydrometer used for beer and wine works on densities lower than water but sugars in drinks are greater than water. Once you have any significant amount of sugar in an alcoholic beverage, your hydrometer becomes basically useless. The measurement of alcohol content is often a problem for makers of fortified wines such as port, sherry, RTDs and liqueurs or any alcohol which contains sugars. Microdistillation One of the methods used for determining alcohol content relies on micro This graphical representation of the photo at left shows how the pieces fit together to analyse alcohol content. distillation, where a predetermined test sample is put into a still and the condensed alcohol is weighed. This has to be done by trained personnel and is expensive! One of our contacts in the liquor industry recently paid $14,000 for an automated instrument of this type! Other techniques such as infrared spectroscopy are also very expensive, typically $25,000 and they have a limited range – you need at least two of these instruments to cover 0-20% and 20-60% alcohol, whereas ours covers 0-95% alcohol. Those instruments are extremely accurate, down to 0.02% and if calibrated correctly will stand up in court. They are highly recommended if you have $50,000 to spare! But if you want something 300 times cheaper you may want to consider our setup which is typically accurate to ±0.5% – maybe not accurate enough for a court of law but more than accurate enough for most users. How it happened Necessity being the mother of invention, we wanted to help a friend who makes wines and other beverages so he could quickly check the alcohol in his liqueur, which contained a lot of sugar. He wanted to know how many “standard drinks” was in a bottle. (We November 2013  73 Here’s a close-up of the heart of the system, the Digitech (Jaycar) QM7302 Breath Analyser. The opaque circular piece at the top is actually the breath tube into which you blow to get a reading of blood alcohol content (%BAC). We’re using it in a different manner than the manufacturer intended! make no comment about his readiness to allow us to sample his wares. . .) Accurate breath analysers, incorporating fuel cells are readily and fairly cheaply available. We thought we might try the one offered by Jaycar (QM7302 <at> $119.00) to see if we could determine the alcohol content of various beverages. We reasoned that if you bubbled some (sober) breath through a warm test sample (body temperature) and measured the outcome, you would be able to calculate the alcohol content. Providing you knew the concentration of that sample you would be able to convert the reading to the percentage of alcohol by volume (ABV). It worked well – in fact, much better than we expected… so here it is! How it works This project uses the fuel cell alcohol tester combined with the Jaycar GH-1301 thermostatically controlled travel mug (to accurately set the temperature), connected by a short tube. The operation is very simple: a 1-4g sample of an unknown alcoholic beverage is made up to 200ml with water and is placed in the travel mug, which is set to reach a temperature of 39-40°C Once the sample solution reaches 40°C you blow into the mouthpiece, bubbling air through the liquid and then read the blood alcohol content (%BAC) from the fuel cell breathalyser. By referring to a conversion chart you will be able to convert a %BAC 74  Silicon Chip reading to %ABV (alcohol by volume) for your test sample. Naturally the dilution of the test sample has to be in the range of the breath tester which is specified at 0.00-0.4%. So you will have to make a weaker solution for strong alcoholic drinks (1g/200ml) and stronger solutions for weak drinks (4g/200ml) and then just read off the chart for that particular concentration. We took quite a few measurements using the Jaycar unit with various alcoholic solutions to establish the conversion chart and were happy that it was accurate and more importantly, the results were repeatable. Some losses will occur mainly in the exit tube where there may be some condensation. Most of it will be water but a tiny amount of alcohol is lost (distillers call this the “angels’ share”). We could heat the tube to prevent condensation but we feel this is not necessary and will complicate the project. Those of you who wish to use the device in the tropics need not worry too much but may find problems if you live in Antarctica or high on Everest’s slopes! Keeping the exit tube short helps considerably and we have set up the chart using a standardised length of tube because a longer tube will incur higher losses. It is easier to take measurements with a longer exit tube but the results will be unreliable. Parts List – Alscolyser 1 fuel cell alcohol breath tester (eg, Jaycar QM7302) 1 heated travel mug (eg, Jaycar GH-1301) 1 105mm length of 10mm PVC or Neoprene tubing 1 unused caulking gun nozzle 1 150mm x 5mm diameter heatshrink tubing 1 laboratory (mercury) thermometer (or thermocouple and DVM) 1 accurate digital scale (eg, Jaycar QM-7264) 1 12V 3A power supply (with lead and RCA plug to connect to travel mug) or use a 12V car battery with the lighter plug lead which is included with the travel mug. Other applications You can also use the setup to check and/or calibrate other breath testers. Many of these are not accurate or they have changed with age, abuse (or simply don’t work at all!). If you are using a personal breath tester, we urge you not to rely on it before you drive, unless you have had it checked. Better still just don’t drink and drive at all! Even wall-mounted units in pubs and clubs can be way off unless they are frequently calibrated according to the manufacturers’ instructions. (Once again, that’s why they have those disclaimers!). We checked a $10 unit and at 0.05% it gave a reading of 0.04%, and at 0.06%, a 0.0% result – so don’t trust them! Calibration for these devices is usually done by putting a standardised alcohol solution, usually 0.38% ABV (alcohol by volume), in a calibrating vessel at 38-40°C. Then the operator blows into it bubbling air into this standardised mixture which feeds to the breathalyser via a short tube. You can check the 0.05% level by weighing 2.5g scotch plus 197.5g water. We have to hope that the operator is not too drunk otherwise the machine will be set incorrectly and will always read too low! In fact, this applies just as much to our system – any alcohol in the operator’s breath will obviously skew the results. So beware – there is no guarantee that any breath analyser, large or small is correct. Unless, of course, it is one in one of those vans with flashing red and blue lights – these are regularly calibrated and are declared (by law) to be scientific instruments which means you can’t argue with their results. To calibrate another breathalyser you can compare a reading from the Jaycar unit to the breathalyser under test. You should try different concentrations of alcohol because one reading is really not enough to verify that it is working. Some breath analysers do not have provision to fit a tube and you only need blow over the top of it for a few seconds. To check these you will only need to aim the exit tube to the receptor and keep it very close. siliconchip.com.au This method is also used by various Police departments to check their hand held breathalysers and they use rather expensive devices to do this! As an aside, this device would have been very handy a couple of decades ago when a certain teenager (who must remain nameless, Craig) developed a taste for his father’s Jim Beam. Said father never did work out why said JB tasted so “weak” until many years later, son admitted to father that he used to refill the bottle behind the bar with water to mask his nefarious activities. So if you think your drinks are being “watered down” at your pub or club, here’s the way to accurately check them! Construction Cut a piece of tubing to the specified length of 105mm and fit a plastic mouthpiece (supplied with the Fuel Cell Alcohol Tester) to each end. Two mouthpieces are provided with each breath tester and you can purchase extra ones separately if needed. Drill two 7mm holes in the lid of the mug as per the diagram and seal the slider with some insulation tape. One of these holes does double duty – it’s used for both a thermometer (or thermocouple) and (when at the right temperature) for the outlet tube. Many thermometers and thermocouples will also fit through the outlet tube anyway, so if yours does the outlet tube can be left in situ. Then fit 165mm of 5mm diameter heatshrink tubing over the end of the caulking gun nozzle and push it into one of the holes. Push your thermometer (or thermocouple) into the other hole. You are now ready to calibrate and test! Operating and calibrating We have made things pretty easy by doing all the calculations and conversions for you but we do recommend a check to ensure the breath tester is working correctly. Firstly warm it up by blowing directly into it to check if the tester reads zero. Obviously, you need to be absolutely stone cold sober for this, otherwise you will have to wait until you zero it. And if you remember that your body only “loses” 0.015% of blood alcohol per hour, that could be a rather long wait! siliconchip.com.au Breath Analysis: the players There are three major types of breath alcohol testing devices, each based on different principles. Regardless of the type, each device has a mouthpiece, a tube through which the person blows air and a sample chamber where the air goes to be analysed. Older style “Breathalyzer”# – Uses a chemical reaction involving alcohol that produces a colour change Intoxilyzer – Detects alcohol by infrared (IR) spectroscopy Alcohol Sensor – Detects a chemical reaction of alcohol in a fuel cell Breathalyzer The Breathalyzer device contains: • A system to sample breath • Two glass vials containing the chemical reaction mixture • A system of photocells connected to a meter to measure the color change associated with the chemical reaction The breath sample is bubbled in one vial through a mixture of sulphuric acid, potassium dichromate, silver nitrate and water. Sulphuric acid removes the alcohol from the air into a liquid solution and the alcohol reacts with potassium dichromate to produce chromium sulphate, potassium sulfate, acetic acid and water.The silver nitrate is a catalyst which makes accelerates the reaction without participating in it. During this reaction, the reddish-orange dichromate ion changes color to the green chromium ion when it reacts with the alcohol; the degree of the color change is directly related to the level of alcohol in the expelled air. To determine the amount of alcohol in that air, the reacted mixture is compared to a vial of unreacted mixture in the photocell system, which produces a voltage proportional to the colour change which is calibrated for alcohol concentration. Intoxilyzer ­This device uses infrared (IR) spectroscopy and identifies molecules ba­sed on the way they absorb infrared light. The various bonds within molecule absorb IR at different wavelengths. In ethanol the bonds (C-O, O-H, C-H, C-C) absorb the IR light at different wavelengths and these wavelengths help to identify the substance as ethanol and the amount of IR absorption tells you how much ethanol is present. A lamp generates a broadband (multiple-wavelength) IR beam, which passes through the sample chamber and is focused by a lens onto a spinning filter wheel which contains narrow band filters specific for the wavelengths of the bonds in ethanol. The light passing through each filter is detected by the photocell, where it is converted to an electrical pulse and then is relayed to a microprocessor which calculates the BAC based on the absorption of this filtered infrared light. In general, the larger table-top units found in Police stations and in some “booze bus” installations are IR spectroscopy types. FUEL cell type ­Moder­n fuel-cell technology (the same as which may power our cars and even our houses some day) has been applied to breath-alcohol detectors. Devices like the one in our project use this technology. The fuel cell has two platinum electrodes with a porous electrolyte material sandwiched between them. As the exhaled air from the breath flows past one side of the fuel cell, the platinum catalyses the oxidation of any alcohol in the air to produce acetic acid and in the process moves electrons across the electrolyte. A voltage is generated between the two electrodes proportional to the amount of alcohol and this is measured and converted to BAC by a microprocessor. The protons move through the lower portion of the fuel cell and combine with oxygen and the electrons on the other side to form water. # “Breathalyzer” is the registered brand name and trademark of a particular manufacturer (specifically Dragerwerk AG, a German conglomerate). However, like many words in our language, it has become synonymous with a wide range of breath analysis devices. We are using the name in this context. November 2013  75 0.25 CONVERSION CHART FOR JAYCAR QM-7302 FUEL CELL BREATH TESTER 0.2 EXAMPLE: 4g/200ml sweet wine – 0.11% BAC measures 7.4% 0.15 BREATH TESTER READING %BAC at 40°C 0.1 0.05 % ALCOHOL BY VOLUME 0 0 0 0 2.5 5 10 5.0 10 20 Then connect the breath tester to the exit pipe making sure that all connections are secure. If you have a balance or electronic scale which is accurate to 0.1g, weigh out exactly 1.0 gram of scotch whiskey (blended scotch is always 40% ABV; you may also use vodka or brandy as long as the strength is 40%) and make this up to 200g with water. Ideally, that would be pure or distilled water but in most circumstances, ordinary tap water will be satisfactory. Note that “normal” kitchen scales will not be good enough unless they are accurate to one gram. To maintain sample accuracy with one gram scales you should multiply everything by ten (eg, 10g/2litres). The Jaycar QM7264 digital scales we used have a resolution of 0.01g. Place the alcohol/water mixture in the travel mug and hook it up to a power source (12V/3A) or to the 12V cigarette lighter socket in your car and set the temperature to 40°C (104°F). When the sample has reached 40°C on your separate thermometer you can pull the plug out because the mug may exceed the dialled in temperature. Conversely, if it doesn’t reach 40°C you may need to set it to a higher temperature. You may wish to leave the mug in its default mode which shows °F, in which case you can do all your measurements at 100°F Every time you remove power to the mug, all settings will be lost. (Every mug will be different so you may need to set it a bit higher if it 76  Silicon Chip 7.5 15 30 10 20 40 12.5 25 50 15 30 60 won’t go to 40°C.) The mug we used is fairly well insulated so it will maintain the temperature for a few minutes, enough to do two or three repeats. For accuracy, you must check the temperature of the sample between tests with a separate thermometer such as a digital thermometer or glass thermometer because the mug is only designed to heat coffee – it is not super accurate. Bear in mind that if it is too hot or too cold your readings will be incorrect. Follow the instructions provided with the QM7302 alcohol tester and warm it up as recommended. When everything is ready and the tester beeps for you to “blow” hold down the button and blow gently and Do’s and don’ts • DO read all the instructions which accompany the tester and the mug. • DON’T switch on the mug without liquid • DO remember temperature is important, so keep the sample as close to 40°C as is possible • DO give the breath tester time to recover after four samplings • DO dry the mug and tubes before adding the sample • DO accurately weigh the sample and water – weigh 1g (or 2g or 4g) then add water to 200g – ie, 1g sample +199g water • DO measure the sample immediately – if it sits too long alcohol will evaporate. 17.5 35 70 20 40 80 22.5 45 90 SAMPLE 4.0g 2.0g 1.0G steadily into the mug for six seconds or until you hear a second beep. Don’t blow too hard or you may risk blowing big droplets into the tester. If all is well, you should get a reading close to 0.20%. Jaycar’s specifications indicate that the accuracy of this tester is ±0.008%. Our measurements of alcohol were typically accurate to ±0.5%, which is almost good enough for establishing a wine alcohol label! The conversion chart shows how to calculate the %ABV of a beverage from a %BAC reading on the Jaycar unit for 1, 2 or 4 gram samples in 200g water. Note that we have specified grams of water here instead of the usual “ml” because you are weighing the sample on the scale, not measuring it by volume. Of course, 200ml of pure water will weigh 200g. Examples Example 1: a 4.0 gram test sample of sweet white wine, labelled 8.0%, gave an average reading of 0.11% so tracing down we will get a measurement of 7.8% ABV. (yellow line) Example 2: a 1.0 gram sample of an unknown spirit gave a reading of 0.215% and again tracing down we get 70% ABV – quite a strong spirit!! If you have no idea what the approximate alcohol content is then do a rough reading using 1g and then increase it to 2g or 4g to get higher readings (and hence more accuracy) on the breath tester. You may need to do a few practice runs to be sure, to be sure! SC siliconchip.com.au