DE2222403A1 - Estimating alcohol content of liquids - esp drinks and blood, by oxidn in nitric acid - Google Patents

Abstract

Quantitative determination of alcohol content in aq. liqs., esp. drinks and blood, by distilling the alcohol from a definite amt. of liq. to be analysed into a receiver contg. a definite amt. of excess oxidising agent and estimating the amt. of non-consumed oxidising agent by back-titration, is effected by oxidising the alcohol in the presence of a high, pref. >20 (>40)% HNO3 concn., esp. using HNO3-Dissolved chromate, at ambient temp. Chromate soln. and HNO3 soln. may be added separately and combined on measuring receiver vol. Chromate soln. is >0.1 (>0.3) oxidn. equiv./l. Non-consumed chromate is reduced with KI, after diluting receiver liquid to an extent such that HNO3 cannot oxidise KI. Process may take place quickly, e.g. 2-5 min, when distilling 10-100 mg alcohol, esp. using 20-50 ml. receivers and slowly, e.g. 10 min, with 5 mg alcohol, using 5 ml receivers.

Description

Method and device for determining the alcohol content of Liquids The invention relates to a method for quantitative EN; mood the alcohol content in watery liquids, at which the alcohol from a certain Amount of the liquid to be examined in a certain excess amount Oxidizing agent-containing template distilled over and there by back titration of the unused oxidizing agent is determined.

With the previous official methods for determining alcohol In liquids containing extracts, especially wine, the alcohol is made from a larger amount of liquid distilled off. The distillation is done slowly, so that there is no loss of alcohol and at least about 2/3 of the liquid is consumed overst411ierto The distillate is carefully caught in the pycnometer, tempered, filled up to the mark, whereupon the specific weight is then determined with a precision balance of the distillate and its alcohol content from it with the help of tables is calculated. This working method is quite time consuming and cumbersome. Will while the alcohol is distilled from an acidified solution, then it is often a The alcohol content was found to be too low, as the sulphurous acid then escaped from the liquid distilled over and the specific gravity in the pycnometer falsified.

It is also known to chemically determine the alcohol content of a distillate To determine ways through the chromosulfuric acid oxidation. As long as the one to be examined Liquid must be distilled in the diligent manner described above, there are no significant advantages associated with it.

From the German Offenlegungsschrift 2 037 920 is a method for determining the alcohol content of aqueous liquids mixed with alcohol known in which the distillation of a small amount of the to be analyzed Liquid-derived alcohol for the purpose of its oxidation with a certain amount a filtered solution of an excess mineral Oxidizing agent is brought into contact and then the amount of excess oxidizing agent is back-titrated, As an oxidizing agent, potassium dichromate is used in sulfuric acid or phosphoric acid solution used, In this process it is possible to use a get by with a small amount of the liquid to be examined, thereby filling the time the determination of the alcohol content is considerably reduced, with the known method but the oxidation works even when using bichromate as a heated acidic liquid relatively slow in front of you, which is why in a self-contained system must be worked with reflux, so because of the slow alcohol oxidation no alcohol losses occur. As the paths from the liquid to be examined to be relatively short to the submission is for the formation of a closed System requires a complicated apparatus, which is accordingly also quite expensive is, The method is therefore not suitable for carrying out as len different Place, because this is too much effort.

It is also known to use alcohol in a mixture of bichromate and nitric acid to oxidize. A simplified, quick and reliable method for the quantitative determination of the alcohol content, however, was also possible with this oxidation mixture not as possible The invention is based on the object, the alcohol content to determine an aqueous liquid quickly and accurately with simple means can without the need for special qualified personnel.

The invention consists in the oxidation of the distilled over Alcohol in the presence of a high concentration of nitric acid he follows. Nitric acid easily forms esters with alcoholic groups. The ester formation takes place already-held at room temperature. A small amount of alcohol in a large excess Nitric acid, as it is presented in the process according to the invention, is therefore practically completely in ester form. Through the esterification of the alcohol will be the two hydrogen atoms adjacent to the alcoholic hydroxyl are particularly mobile. This enables the alcohol to be oxidized using oxidizing agents known per se greatly accelerated.

Nitric acid is preferably used as the oxidation mixture in the template dissolved chromate used. There is potassium chromate dissolved in strong nitric acid practically completely as CrO3, to which the mobile hydrogen atoms are attached can attach. The chromium VI molecule can now help in the separation of this complex take the attached hydrogen atoms with them, transitioning to the trivalent state, leaving behind the alcohol molecule, oxidized to acetaldehyde. To the hydrated Acetaldehyde molecules can in turn add CrO3. In the further oxidation reaction acetic acid and trivalent chromium are then formed. The equivalency Evaluation of this reaction mechanism suggested that the speed with which alcohol by potassium chromate dissolved in essentially concentrated nitric acid can be oxidized by higher potencies of the respective reactants and the nitric acid depends. This means that by increasing the chromate concentration and also the The concentration of alcohol in the oxidizing solution is strong Acceleration of the oxidation process is obtained. In fact, it succeeds due to these considerations using concentrated nitric acid instead of the sulfuric acid previously used in chromate oxidation and by increasing the Concentrations make the conditions so that alcohol is already at room temperature is instantly oxidized to acetic acid.

In a preferred embodiment of the invention, the Oxidation of the alcohol carried out essentially at ambient temperature. To the The nitric acid in the initial charge expediently accelerates the formation of esters at least about 20 percent, preferably at least about 40 percent, nitric acid before.

The chromic acid concentration in the original is also as high as possible kept, for reasons of economy expediently the presented excess Amount of chromate distilled over the expected amount of the liquid to be examined Do not excessively exceed the amount of alcohol. For example, if drinks are examined, whose alcohol concentration is in the range from 0 to 100 g per liter, so will advantageously presented an amount of chromate that has a concentration of 120g Alcohol per liter of the liquid to be examined.

The chromic acid is generally in one concentration in the original of at least 0.2, preferably at least about 0.3 oxidation equivalents per liter Contain liquid In a particularly preferred embodiment the inventive method is the unused chromic acid after Alcohol distillation is reduced with potassium iodide, the original liquid beforehand is diluted with water to such an extent that the nitric acid present becomes potassium iodide unable to oxidize7 The iodine excreted can then be combined with thiosulphate titrated The rapid oxidation of the distilled alcohol in the original liquid enables the alcohol to be distilled very quickly from the solution to be examined, without alcohol losses having to be accepted. that the alcohol only briefly comes into contact with air due to the rapid distillation comes, so that a possible source of error is eliminated here as well. Because of the The accuracy of the method according to the invention can thus be achieved with very small quantities get by with the liquid to be examined, e.g. with the usual wines Amounts that are in the size range of about one milliliter «This amount of liquid is expediently diluted before distillation (ten to twenty times', This dilution enables distillation with a high temperature gradient to work between the heating device and the liquid to be examined, whereby the distillation of the alcohol is accelerated without evaporation of the to liquid to be examined up to Dryness must be feared.

In a particularly suitable embodiment of the invention The process is carried out in the distillation without water cooling. Is preferred on the other hand a fraction run <j of the evaporated alcohol-water mixture, da On the one hand, this ensures that the liquid lost in the distillation vessel is kept low, on the other hand the Al-alcohol in the most concentrated form possible is forced into the volage vessel, which is particularly important with low alcohol levels in the range up to approx. 4g per 1 is important, provided that. the determination will be accurate target. Even if some of the alcohol enters the original liquid in the form of a ampoule, so it is completely caught there and oxidized, <a the oxidation very quickly goes on and the initial liquid has a much lower temperature than the alcohol vapor.

due to the peculiarity of the method according to the invention it is possible to work with a particularly simply designed distillation device. The invention therefore also relates to a device for carrying out the alcohol distillation according to the invention. This device is one with fillers filled column provided, at the lower end of which a distillation flask can be connected is and its upper one directly with a transfer pipe for transferring the den alcohol-containing distillate is connected to the template. The transfer pipe is set up in such a way that its lower open end enters the original liquid can be immersed.

In the embodiment of the device according to the invention and in the Distillation comes with the help of the device it at higher alcohol concentrations on the order of 10 to 1009 alcohol per liter of liquid to be examined It is less important to separate alcohol and water as completely as possible using the fractionator, i.e. the alcohol if possible Overdrive anhydrous. This would require the distillation to be slow would have to be made. The main task of the fractionation facility is at this concentration range in that it is the reflux caused by the column enables small amounts of liquid to be distilled quickly under the application of intense heat, without fear of excessive constriction of the liquid However, the concentration of the alcohol caused by the fraction essay as Advantage welcomed. With the help of the distillation device according to the invention it is thus possible the alcohol content of 1 ml of the liquid to be examined within of three minutes to be quantitatively exaggerated into the template, where the alcohol is then according to the invention is oxidized immediately and quantitatively to acetic acid. For liquids with low Concentrations of alcohol, e.g. blood, reduce fractionation by slowing it down Heating up fully used, so that the alcohol in concentrated form as completely as possible passes over at the beginning of the distillation, which will be discussed in more detail below will.

Thus, in preferred embodiments of the invention, the alcohol content becomes of the liquid to be examined at alcohol concentrations in the range of 10 to 100g alcohol per liter, e.g. for alcoholic beverages, from one Volume of approx. 10 to 15 ml with a low fractionation effect within approx. Distilled over into the receiver for 3 minutesa With alcohol concentrations below approx. 5g Alcohol per liter the alcohol content is one milliliter of the liquid to be examined, however, with extensive fractionation from one Liquid volume of approx. 5 to 10 ml within a period of approx. 8 minutes distilled over.

Similarly, by dimensioning the volume of the original liquid ensured that the concentration of the distilled alcohol in the original liquid is kept as high as possible. This is how the initial volume for the distillation of approx. 10 to 100 mg alcohol, preferably approx. 20 to 50 ml and during the distillation of less than about 5mg alcohol kept to less than about 5 ml. By as much as possible local limitation of the over-distilled alcohol in the initial liquid, i.e. by avoiding an immediate dilution of the alcohol with the original liquid it can also be ensured that the alcohol concentration is kept high and the oxidation takes place very quickly. This is achieved in a simple manner by that the end of the distillation device which is immersed in the initial liquid is designed as an ordinary tube that is open at the end.

If the alcohol determination is to meet more stringent requirements, especially with very small amounts of alcohol, continue the distillation until until the template comes to the boil due to the passing vapors. In this way is essentially all of the amount of alcohol that is relatively concentrated Form passes over, oxidizes in the cold. After the main amount of alcohol has been oxidized possibly small amounts of alcohol still present in the initial liquid, the oxidation of which proceeds slowly because of the increased dilution, are then as a result the increase in temperature also oxidized quickly and quantitatively. To this For this purpose, the amount of the initial charge and the heating power of the heater are preferred set so that the Submission liquid within a period of time of less than 10 minutes, preferably within a period of less than approx. 8 minutes after heating the liquid to be distilled begins to boil. A heater with adjustable heating power is particularly suitable as a heater, e.g. an adjustable mirror burner.

The following are further features and special features of the invention Procedure for determining the alcohol content for liquids with low alcohol concentrations, especially for the determination of blood alcohol, a well-known depicted, often The method used to determine blood alcohol is the so-called "Widmark method", in the case of alcohol by evaporation from a bowl of a two-bowl vessel in A second shell containing the oxidizing agent is transferred and oxidized there will. The process is very time and material consuming. A determination must be 3-fold and can be carried out with three times the blank value a The duration of a determination is at cae three hours. This requires very careful and skillful work. Nevertheless, the accuracy is only moderate.

In contrast, a blood alcohol determination can be carried out according to the method according to the invention can be carried out very quickly in a simple manner and with a minimum of equipment The process is easy to standardize, so that even a chemical layperson after a short time Exercise Can Achieve Reliable Results0 Furthermore, the procedure is regarding its feasibility is not tied to a specific laboratory, but can with Also needed, for example, in a writing room (e.g. at a police station immediately after taking blood) will. The necessities Reagents are stable. Comparison standards with alcohol are not necessary, and it can work in the order of magnitude of the currently usual accuracy without a blank value will. However, more precise results can also be achieved in the determinations. Only a small amount of blood (approx. 1 ml) is required to carry out the determination. Farther the determination can be carried out in such a way that no pretreatment of the blood is necessary is. Rather, the blood or, which is kept liquid by additives during removal, can be used Blood plasma can be used directly. The blood alcohol determination is carried out as above already mentioned, according to the same principle which the determination of alcohol ic Liquids with a higher alcohol concentration are used. There was, however Difficulties of a fundamental nature to be solved, which are related to the circumstance, that the alcohol does not distill out quantitatively from undiluted blood and in one milliliter of blood only extremely small absolute amounts of alcohol (0 up to 3mg alcohol) are contained in comparison to about 50 times the amount in alcoholic Drinks, such as wine Because of its high protein content, blood tends to be even in diluted form Condition strong for foaming. The usual defoamers do not work sufficiently enough, and protein precipitation would result in too great a dilution or it would be greater Amounts of blood required. It has now been found that the addition of acetic acid too blood is effective against foaming. This has a dilution of the blood with about 20% acetic acid to about 10 times the volume as special proven favorable. It has been shown that 1, oil blood after dilution with 8ml 20% acetic acid only foams briefly at the beginning during the distillation then can be distilled without difficulty. At the initial foaming, you can in certain circumstances small amounts of the distillation material for one briefly in the lower area of the fractionation part of the distillation device get, but this is not harmful.

When adding acetic acid, however, it must be noted that the result is the blood alcohol determination is not affected by the impurities in the vinegar is provided. Even glacial acetic acid p.a. contains traces of substances that deal with chromium nitrate let acid oxidize. As the traces contained e.g. in 8ml of 20% acetic acid have a noticeable effect in relation to the minimum amount of alcohol, the blank value of the acetic acid should be taken once each time a new batch of acetic acid is opened Acetic acid can be determined by distillation so that it is used in the later Regulations can be taken into account. In the case of the 20S igen used by the applicant Acetic acid, for example, resulted in a blank value of 0.02 per thousand alcohol, which is astonishing is little.

Except that due to the thinning of the blood to about 10 times due to the very low alcohol concentration in the liquid to be distilled For the determination of blood alcohol it is also important to note that the volume of the submitted oxidizing liquid not in comparison to the ratios at the Reduce alcohol determination from GetrAnlXen while maintaining the concentration On the other hand, it is said to be responsible for the particular reactivity of the nitric acid-chromic acid oxidation solution the highest possible concentration of all reaction partners should be sought so that rapid quantitative oxidation of the alcohol to acetic acid even at room temperature he follows.

Experiments could confirm that the slow fractional distillation of the blood to be examined and thus the ~ * dh centering of alcohol to such an extent has a positive effect on the desired complete oxycation of alcohol without affecting the accuracy of the alcohol determination it is possible to work with relatively large amounts of liquid in the template. By Fractionation is achieved that essentially all of the alcohol is already passes over with the first drops of distillate and thus the effective alcohol concentration initially, i.e. before further distillate portions, a reduction in concentration cause it is so high that the oxidation of the alcohol is already practical in the cold is completely finished before the subsequent condensing distillate vapors Dilute a small amount of the initial liquid and bring to the boil. But also in the case of slow fractional distillation, care should be taken to ensure that no larger amount of liquid is distilled over than is absolutely necessary is. The vaporous distillate should also be used in the slowed-down distillation Entry into the original liquid to be cooled down so far that its supplied Heat energy, the small amount of initial charge not before completion of the quantitative oxidation brings to the boil.

As already mentioned above, the controlled fractionated Carry out distillation easily with an adjustable mirror burner. The one brought onto the market by E. Bühler (Tübingen) is particularly suitable continuously adjustable mirror burner type 500 t No. 888, 220 V, 300 watt, the 10th has drawn heating levels. To standardize blood alcohol determination the heating output of the heater can be set in such a way (with the above mirror burner about position 6) that the amount of liquid coming to the distillation of approx. 10 ml begins to boil after 2 minutes and after another two minutes the first drops of distillate (concentrated alcohol) in the descending part of the distillation tube condense. If the distillation is continued, it will distill for the next 4 minutes 4 to 5 ml of distillate over, and at the end of a total of approx. 8 minutes is the initial liquid boiling hot or starts to boil by itself.

In order to always have the same conditions (is for consecutive Serial determinations important) and those achievable with a cold fractionation attachment The distillation device will ensure a much better separation effect cleaned preferably by backwashing with cold water between two determinations. To do this, it is advisable to proceed as follows: After the distillation has ended one dips the open end of the distillation tube into a distilled one with approx. 50ml Water-filled vessel to the bottom. Then you cool it on the fractionation section hanging lCaoml Erlenmeyer flasks with cold tap water. By doing it resulting underpressure, the 50ml of distilled water are quickly transferred to the cooled Erlenmeyer flask withdrawn. This becomes the fractionation part of the still practically cooled down to normal temperature again. At the same time, however, the The fractionation attachment cleaned when the blood-containing distillation liquid is foamed for the first time some blood got into the fractionator. As a filling material for the fractionation part The glass beads used are particularly easy to clean.

Around. avoid that by changing the process conditions unintentional and undetected methodological errors resulted in the following Test series carried out: a) With concentrations kept constant of nitric acid and ralium chromate became the concentrations of alcohol varies. This experiment had to provide information about the influence on the reaction rate by giving the effective alcohol concentration.

b) With the concentrations of alcohol and potassium chromate kept constant the effective nitric acid concentration was varied. This attempt had to Recognize the dependence of the reaction rate on the nitric acid concentration permit.

To a) Concentration of nitric acid: constant 37 grams in 100 ml Concentration of potassium chromate: constant 750 mg / 100 ml concentration of alcohol Reaction time up to in mg / 100 ml end of reaction mg / 100 ml log of this time in seconds log of which 178 2.25 190 2.28 356 2.55 47 1.67 534 2.725 23 1.36 712 2.855 13 1.11 890 2.95 9 0.955 Regarding b) Concentration of the alcohol: constant 320 mg / 100 ml concentration of potassium chromate: constant 1350 mg / 100 ml Concentration of Nitric acid reaction time to end in grams per ml of the reaction grams in 100 ml log of which time in seconds log of which 37 1.57 140 2.15 17.9 1.25 1500 3.17 12.3 1.09 4800 3.71 9.0 0.95 11 100 4.04 7.1 0.85 20 000 4.30 If you take the logarithms of the Concentrations versus the logarithms of the times result in straight lines from which the potency factors can be calculated with which the concentrations of the reactants Alcohol or nitric acid influence the reaction rate.

It could be determined experimentally that the reaction time inversely proportional to the 3rd power of the nitric acid concentration and the 2. Potency of alcohol concentration.

According to this, even a slight increase in the nitric acid concentration causes a significant reduction in the response time. Likewise, by increasing the effective alcohol concentration (below effective is the one at the moment of Penetration of the alcoholic distillate into the original liquid at this point to understand the prevailing concentration) by e.g. a 10-fold increase in the reaction rate achieve 100 times. So it is of the utmost importance that the alcohol appears as completely as possible in the original in one shot, because then the effective alcohol concentration is many times greater than when the alcohol distributed in small spurts over a normal distillation diagram arrives.

It is also important for an initial concentration to be as high as possible of nitric acid.

And finally, it is of considerable importance that the in-focused Alcohol that arrives in the form remains locally in this concentration for as long as possible, does not immediately distribute itself under the original liquid, because otherwise its effective local concentration would be greatly reduced. For this purpose one leaves the condensed alcohol distilled over in concentrated form as calmly as possible and get into the original liquid while avoiding turbulence.

Although the concentrations in the template for the blood alcohol determination for the reasons already described with regard to potassium chromate and alcohol not in the order of magnitude possible when determining alcohol in beverages, such as wine can be held, is sufficient, as can be seen from Tables 1 to 3, as a result the more careful fractionation with the associated longer residence time of the alcohol in the reaction liquid is the achievable reaction rate already at room temperature to guarantee complete oxidation.

Table 1 shows the results of experiments from which it can be seen that the alcohol content of interest for a blood alcohol determination within the intended maximum exposure time of approx. 4 minutes be completely oxidized at room temperature. The results show that up to Blood alcohol content of 2.5 parts per thousand within the error range the complete Oxidation expires within the time. So it is certain that provided the alcohol quantitative within the intended distillation time of a total of 8 minutes distilled over, the oxidation also proceeds quantitatively, especially towards the end of the distillation nor the temperature effect, which greatly increases the reaction rate.

Table 1 Per 1.0 ml of purely aqueous solutions of different per mille alcohol content added to 4 ml of reaction solution, waited 4 minutes at room temperature and then titrated.

Present target value in found value in per mille per mille 2.505 2.49 2.004 1.98 1.503 1.505 1.002 1.005 0.501 0.500 0.251 0.260 In Table 2 are the alcohol content of 1 ml of aqueous alcohol solution each diluted with 8 ml of 2% acetic acid listed which were recovered during the distillation. Again you can see that up to alcohol contents of 2.5 parts per thousand the submitted alcohol contents within the error spread-be found again. So it finds both a quantitative one Distillation such as quantitative oxidation of the alcohol takes place.

At the mean value "1.505 per thousand" was repeated 8 times the mean error of the determination determined: it is j 0.012S per mil, ist thus significantly less than with the previously known methods.

Finally, it was checked whether and to what extent acetone (which is in the Practice a few volatile compounds contained in the blood through which higher blood alcohol levels could be faked, for example in people with diabetes) pretended under the conditions of the determination of blood alcohol. At room temperature acetone does not become at all in the usual times oxidized. At boiling point, 1 per mille acetone simulates 0.008 per mille blood alcohol, i.e. also in the case of a diabetic, elevated blood alcohol is not fooled.

Table 2 The same target alcohol values (1.0 ml each) according to the instructions for blood alcohol determination distilled and titrated example 2).

Submitted target value in per mille Found value in per mille 2.505 2.48 2.46 2.48 2.51 2.004 1.503 2.005 2.005 2.010 1.505 1.480 1.490 1.510 1.510 1.503 1.503 1.500 1.520 1.505 1.500 1.002 1.000 0.501 0.515 0.251 0.245 Mean Error, calculated from the 8 repetitions of the value i, 503 of Table 2: mean = Mean error = # 0.0125 per mille.

Finally, in Table 3, the results are set down, which are the real ones Object, namely blood, were found.

The experiments were made so that instead of 8 ml of a 2q% Acetic acid only 7 ml of a 23% acetic acid with 1.0 ml ox blood (which is caused by sodium citrate liquid) and with 1.0 ml of alcohol solutions of increasing alcohol content were added and distilled.

Here, too, the accuracy and reproducibility of the determination can be seen Tabel 3 distillation results using ox blood with different added alcohol levels.

Present target value in per mille. Recovered value in per mille 2.44 2.402 2.412 2.402 2.422 1.83 1.812 1.812 1.832 1.22 1.232 1.222 1.222 0.61 0.622 0.612 0.612 0.244 0.242 0.242 0.242 0.122 0.122 0.122 0.132 Other features of the invention emerge from the following description of embodiments in connection with the claims and the drawing.

The drawing shows an embodiment of the distillation device according to the invention in a schematic representation.

An essential part of the illustrated distillation device is a curved glass tube 1, with an ascending section 2 and a descending section Section 3.

Part of the ascending section 2 is a fractionation attachment 4 uneducated. For this purpose, the glass tube 1 is over the length of the fractionation attachment inflated to about three times the diameter and filled with solid bodies (glass beads, Raschig rings or the like.) Filled, which are necessary for a fractional distillation theoretical soils. Shortly after his transition from the larger to the The glass tube ends with a smaller diameter at the lower end of the fractionation attachment. Over this lower end 5 is a polyethylene stopper 6 provided with a hole pushed, the outer diameter of the opening of a 100 ml Erlenmeyer flask 7 corresponds.

The ascending section goes just above the fractionation attachment 4 2 of the glass tube into the descending section 3, which becomes a simplified Handling of the distillation device from a sloping downward part 8 and a part 9 directed vertically downwards.

When the distillation device is set up, the glass tube 1 is (not shown in the drawing) vertically displaceable tripod held.

The Erlenmeyer flask 7 is sufficiently firm over the stopper 6 connected to the glass tube 1. In this way, by lifting the glass tube 1 the Erlenmeyer flask 7 can be lifted from a heating device 10.

A mirror burner is advantageously used as the heating device. At the same time, by lifting the glass tube 1, the lower end of the vertical Part 9 taken out of a template liquid 11, which in a larger Erlenmeyer flask 12 serving as a receiving vessel is located.

EXAMPLE The following example, which is a preferred embodiment of the invention is standardized to determine the alcohol content of beverages that contain between 0 and 110g alcohol per liter. Should drinks are examined whose alcohol content is over 110g per liter, a correspondingly smaller amount of the beverage to be examined for the alcohol determination measured and inserted.

Since the example is a standardized determination method the concentrations of the individual reagents are coordinated so that that the alcohol content of the drink in each case in a simple manner from the analysis result can be determined. In detail, for the implementation of the alcohol determination the following solutions are used: Solution A1 w 67.445g potassium chromate z.A. in distilled Dissolved water and filled up to the mark in the liter flask at 200C.

Solution A2 - 770 ml concentrated nitric acid e.g.

(65X) diluted to 1 liter with water.

(65% nitric acid can also be used directly).

Solution A3 "300g potassium iodide pure (DAB 7) with the addition of 100 ml n lye dissolved in water and diluted up to the liter.

Solution A4 "86.194 g of thiosulphate, e.g. with the addition of 100 ml of n alkaline solution Dissolved in approx. 500 ml of water and filled to the mark in a liter flask at 200C.

Solution A5 - fOg soluble starches z.A. (DAB 7) in 500 ml of hot water entered and dissolved by boiling. After cooling, add 500 ml of water in which 20g of potassium iodide are dissolved with the addition of 10 ml of n-alkali.

The concentrations of these solutions are coordinated in such a way that that 10 ml of solution A1 an amount of 30 ml of solution A4 or 120 mg of ethyl alcohol correspond.

10.0 ml are left in a 500 ml flask with the fine burette Pour in solution A1 (chromate solution). For this purpose, 25 ml of solution A2 (Nitric acid) given. A 100 ml Erlenmeyer flask is filled with 12 ml of water. A few finely-grained accessory stones (approx. O, Sg) are added, which are used as small boiling stones to serve. Then 1.0 ml of wine is poured in with an accurate, well-draining pipette. If necessary, was. the wine has been freed from carbonic acid beforehand. Letting in of the wine in the Erlenmeyer flask takes place in the usual, reproducible manner. When drawing up the wine in the pipette, the wine should as little as possible over the Mark, otherwise wine will stick in the upper part, which will later runs afterwards and thus leads to an excess supply, which is significant with these small quantities Wine could lead.

The 100 ml Erlenmeyer flask is now on the polyethylene stopper of the distillation apparatus connected. The whole apparatus is lowered until the small flask is in the center of the mirror burner seated, while at the same time the 500 ml submission flask with the submission liquid is placed so that the end of the air cooler "in the template liquid immersed as far as possible, preferably sitting practically on the floor.

A laboratory alarm clock is set for 3 minutes. At full heating power of the mirror burner, the liquid will start to boil after about 45 seconds and after another 30 seconds distill over. In order to use these time values of To be able to start working, the mirror burner should be used before the first determination Bake in each series for about 8 to 10 minutes.

After the set time has elapsed, the distillation apparatus lifted vertically a few centimeters. The liquid will continue to boil and rinses any remaining liquid in the pipe end of the distillation apparatus the end. After about 10 seconds then the end of the air cooler with the squirt bottle rinsed to the outside Now the distillation apparatus is raised so far that it can be swiveled on its side and the original can be removed is diluted with 250 ml of water, rinsing the inner wall of the flask, around a drop of wiping that may still hang on top into the To transfer liquid. Then 10 ml of solution A3 (potassium iodide) are added and the excreted iodine with solution A4 (thiosulfate) using one of titrated below the illuminated magnetic stirrer. When the dark brown color turns into a light one Yellow or yellow-green passes over, interrupt the titration and add 10 ml of the solution A5 <starch solution). Now titrate carefully and only drop by drop until the initially deep blue-black Parbe in a transparent light blue and finally merges into the green of the Chron III salt.

This transition is already brought about by a drop, which is why to avoid over-titration, wait about 2 to 3 seconds after each drop, before adding a new drop.

If a ml of solution A5 was used up during back-titration, then contains the wine (i20 - 4a) grams of alcohol per liter.

As mentioned above, the detection range of the solutions is the ones given Amounts set to 120g per liter of alcohol0 However, it is advisable to use with an alcohol content of over 100g per liter, less than 1 ml of drink is used, or the drink has been diluted beforehand because the theoretical Oxidation capacity the equilibrium concentrations no longer 100% Oxidation is sufficient. But you can also and preferably also the amount of chromate Increase the chromate concentration in the template if liquids with higher Alcohol content should be examined.

Series tests carried out as comparative tests have shown that the determination method according to the invention despite the small amounts of liquid used of the beverage to be examined has at least the same Ge accuracy as the official distillation process.

From this is the big one with the determination method according to the invention associated advantage evident, since the determination method according to the invention also can be carried out quickly and safely by non-specialists within a short period of time can, the outlay on equipment being reduced to a minimum.

Example 2 a) Tools for determining blood alcohol content Distillation tube as shown in the drawing with glass beads, tripod for this in a known way, Infinitely adjustable mirror burner, 300 watts, with graduations for fixing the once determined optimal heating output, ideally the mirror burner already mentioned from E.

Buhler. Then the optimal setting no longer needs to be specifically determined because it was tested at position 6. 100 ml Erlenmeyer flasks, test tubes, Capacity about 40 ml, with spout, titration burette according to Steinert, 30 ml, divided into 600 graduation lines (one division = 0.005 per thousand), 200 ml wide neck serlenmeyer for titration, funnel for rinsing over, 1.0 ml blow-out pipette for removing the aqueous potassium chromate titler solution, 1.0 ml enzyme pipette for removing of 1.0 ml of blood (resp.

Blood serum), 3 ml safety pipette for withdrawing concentrated Nitric acid or equivalent Citopipette with storage vessel, 8.0 ml pipette for Withdrawal of the 20% acetic acid, 10 ml measuring cylinder or automatic measuring cup for adding 10 ml of potassium iodide or starch solution.

Reagents: solution B1) = 16.86125q potassium chromate z.A. in distilled Dissolved water and topped up at 200 to the liter.

(You can also use 250.0 ml of the "Alcohol A 1" solution from Example 1 to be filled up to liters).

Solution B2) = 2.15485g sodium thiosulphate dissolved in 10 ml n / 1 sodium hydroxide solution and filled up at 20 ° to the liter mark. (You can also use 25.0 ml of the "alcohol A4 "to be filled up with 10 ml of nil sodium hydroxide solution to the liter).

Solution B3) - 65% nitric acid z.A.

Solution B4) - 6% potassium iodide solution: 60g potassium iodide with.

20 ml n / l sodium hydroxide solution dissolved and made up to the liter. (It can also di.e solution "Alcohol A3" - Example 1 - with distilled water to 5 times be diluted).

Solution B5) = 0.2% starch solution <2g soluble starch z.A.

Pour into boiling water and bring to the boil until the solution is clear. To Add 10 ml n / l sodium hydroxide solution to the cooling and 209 potassium iodide to the liter fill up) Solution B6) B 20% acetic acid: 200 ml glacial acetic acid e.g. at 200 to. Liter diluted.

b) Execution of the determination: If one has not already tried the one Stepless mirror burner from Bühler, then calibrated in a few preliminary tests the mirror burner in question to the correct heating output as follows: One gives 8 ml solution B6 and 1.0 ml distilled water in a 100 ml Erlenmeyer flask and granular pumice stones, connects it to the distillation pipe and lowers the apparatus so far that the Erlenmeyer flask sits full on the mirror burner. Man observes the time until the contents start to boil vigorously By regulation the heating output is searched for the heating output position in several repeated attempts, at which the contents of the flask boil exactly after 2 minutes, this heating power setting is noted or fixed. In a final attempt one is convinced that with cold fractionation part after 2 minutes the flask contents start to boil, after another 2 minutes the first drops of condensate settle in the sloping part of the transfer pipe form and after a further 4 minutes about 4 to 5 ml of condensate into a by placing a test tube cooled in cold water If these conditions are met, the correct heating output setting is available For the actual determination, the mirror burner is set to the fixed heating position set (in the above-mentioned Bühler mirror burner to position It6 ") e Vor a determination or series of determinations is allowed to bake in for about 10 minutes 1.0 ml of solution "B1" and 3 ml of solution "B3" are placed in a test tube. (HNC3 concentration - 50% In 8 ml of tB6tt solution are added to the 100 ml Erlenmeyer flask and grained pumice stones. To this end, 1.0 ml of blood is given and the flask is attached to the Distillation pipe connected. Now the still pipe is lowered so far that the Erlenmeyer flask sits full on the mirror burner. At the same time placed the test tube with the oxidizing liquid so that the end of the transfer tube the distillation device is inserted into the test tube. Now there is an alarm clock set to 8 minutes and then the test tube raised so far that the end of the distillation tube sits on the bottom of the test tube. The test tube will fixed in this position by a clamp. With correctly set heating power the contents of the Erlenmeyer flask begin to boil after 2 minutes. Here comes there will be a brief foaming, with possibly some foam in the fractionation section can occur. After that, the liquid will calm down and continue to boil normally.

After a further 2 minutes, the first portions of the distillate pass over. To a further 4 minutes 5 to 8 minutes in total) the distillation is ended. the The pre-storage liquid has now boiled hot bw. has already-shortly before started to boil. Now the test tube is lowered so far that the end of the The transfer tube is about 5 cm above the surface of the liquid. One still leaves Continue to boil for about 15 to 20 seconds. Remnants of the original liquid, which may still be in the end of the transfer pipe, flushed out. Well splashes the outside of the Uber.Leitungsrohrs with distilled water and lifts the distillation device so far ali that the test tube can be removed. The still with The attached Erlenmeyer flask is swiveled to the side. Now you dip the end des, transfer pipe by lifting it up one with about 50 ml distilled Water-filled vessel down to the bottom of the vessel in the distilled water a. The Erlenmeyer flask is then cooled by immersing it in a beaker with cold tap water.

Due to the negative pressure generated, the 50 ml are distilled Water drawn into the Erlenmeyer flask. This makes the still, in particular the glass bead filling of the fractionation part is cooled down to room temperature again and cleaned if necessary. The next batch can be connected immediately.

The contents of the test tube are rinsed with the aid of a funnel and a squirt bottle quantitatively into a 200 ml Erlenmeyer flask. Decu add about 50 ml of distilled water, 10 ml of solution tBB4tX and 10 ml of solution "B5". The now deep black-blue solution mixture is initially titrated quickly with solution "2" (let it run in a thin stream) until a transparent light blue appears.

Now titrate carefully drop by drop until the water color is pure there is.

If b ml of thiosulphate were used to titrate the blood alcohol, and if the determined blank value is a ml, then the blood contains 0.1ab} per thousand Blood alcohol. a is the consumption of thiosulfate solution (B2) in ml without added blood (Blank value). To the blank value; The titer solutions are coordinated so that 1.0 ml of solution "B1" or 30.0 ml of solution 2B22t with a blood alcohol content of 3.00 per mille correspond.

Since the 20% acetic acid but traces of volatile oxidizable Contains substances, you should open each new batch of 20% acetic acid determine the blank value a. For this purpose, two batch distillations are used (8 ml of the Acetic acid, 1.0 ml distilled water). The mean of the two titrations (which if working correctly by no more than 0.2 ml of the solution "B2't should differ) results in the blank value a ml. This applies as long as the same Batch acetic acid is used.

Like the other solutions, the titer solutions are very long durable.

Duration of a determination: 10 minutes. In the case of series analyzes, during the previous determination and the next determination to be prepared.

Incidentally, it must be pointed out that instead of whole blood blood plasma or blood serum can also be used for the determination. The found Per mille then only have to be multiplied by the empirical factors are known and practiced. In this way, if you wish, you can soothe your blood and then use the serum separated from the blood cake, which contains the alcohol then naturally contains in a higher concentration than the original blood. To the There are recognized conversion factors for conversion to the alcohol content of the original blood.

Finally, it should be noted that in determining the alcohol in Beverages usually do not depend on an accuracy of the 2nd decimal, so that the last traces of alcohol, which may have occurred during rapid distillation (3 minutes) do not skip over, have no influence on the result. Always stand for drinks correspondingly large amounts of liquid are available, so that even with low alcohol contents (e.g. for fruit juices, where yes; only look for alcohol quantities up to 5g / l) the rapid distillation according to Example 1, the alcohol values also except for the 2nd Decimals can be determined, ria one here instead of 1.0 ml of 10 or 5ml the liquid to be examined with appropriate supplementation of Liquid volume, e.g. the 13 ml used in Example 1, can be assumed and then divide the result by 10 or 5, respectively. On the other hand, there is never so much blood available, because of the high protein content it cannot be used undiluted However, an accuracy of up to the 2nd decimal must be achieved here with only 1 ml so that, unlike drinks, it actually matters here, too to distill over the last gamma values.

Claims (20)

Expectations Method for the quantitative determination of the alcohol content of aqueous Liquids, especially beverages and blood, in which the alcohol comes from a certain Amount of the liquid to be examined into a certain excess amount Oxidizing agents containing publishers distilled over and there by back titration of the oxidizing agent that has not been used is determined, characterized in that the oxidation of alcohol in the presence of a high concentration of nitric acid he follows. 2. The method according to claim 1, characterized in that as a template chromate dissolved in nitric acid is used. 3. The method according to claim 1 or 2, characterized in that the Nitric acid to accelerate the formation of nitric acid esters in the template at least is present as about 20%, preferably at least about 40%, acidic acid. 4. The method according to any one of claims 2 to 3, characterized in, that chromate solution and nitric acid are set separately and only be; the dimension of the original volume are combined with one another. 5. The method according to any one of claims 1 to 4, characterized in that that the oxidation of the alcohol is carried out at ambient temperature. 6, method according to one of claims 2 to 5, characterized in that that the chromate in the original is at a concentration of at least approx. 0.1, preferably at least about 0.3 oxidation equivalents per liter is included. 7. The method according to any one of claims 2 to 6, characterized in that that unused chromate is reduced with potassium iodide, the original liquid is diluted beforehand to such an extent that the nitric acid present does not contain the potassium iodide able to oxidize. 8. The method according to any one of the preceding claims, characterized in, that the alcohol content of only 1 ml of the liquid to be examined after their prior dilution is distilled over and determined. 9. The method according to any one of the preceding claims, characterized in, that when overdistilling the alcohol of the liquid to be examined in the Submission of a fractionation is carried out. 10. The method according to claim 9, characterized in that in the The lower the distillation that is to be distilled, the more fractionated it is Is the amount of alcohol and the more precise the determination should be. 11. The method according to any one of the preceding claims, characterized in, that the overdistillation of the alcohol from the liquid to be examined into the Submission of alcohol to be distilled over amounts of approx. 10 to 100 mg quickly, preferably within a period of approx. 2 to 5 minutes, and for alcohol quantities below approx. 5 mg taken slowly, preferably over a period of about 10 minutes will. 12. The method according to any one of the preceding claims, characterized in, that the initial volume in the distillation of alcohol amounts in the range of approx. 10 to 100 mg approx. 20 up to 50 ml and with amounts of alcohol less than approx. 5 mg is less than approx. 5 ml. 13. The method according to any one of the preceding claims, characterized in that that the alcohol which has distilled over is introduced into the original liquid, that it is diluted as little as possible in this before its oxidation. 14. The method according to any one of the preceding claims, characterized in that that the distillation is carried out without special cooling. 15. The method according to any one of the preceding claims, characterized in that that 'especially with amounts of alcohol to be distilled of less than about 5 mg, is distilled until the initial liquid is approximately at boiling temperature is heated. 16. The method according to claim 15, characterized in that the amount the feed liquid and the heating power can be adjusted so that the feed liquid within a period of less than about 10 minutes, preferably within of approx. 8 minutes from the heating of the liquid to be examined to approximately boiling temperature is heated. 17. The method according to any one of claims 9 to 16, characterized in that that the fractionation device, especially for the determination of blood alcohol, between two successive determinations - in each case by sucking back distilled Water is cooled and purified. 18. Device for carrying out the alcohol distillation after a of the preceding claims, characterized in that one filled with fillers Fractionator (4) is provided, at the lower end (5) a distillation flask (7) can be connected, and its upper end directly with a transfer tube (8,9) for transferring the alcohol into the template (11,12) connected is. 19. The device according to claim 18, characterized in that the Fractionation attachment (4) filled with glass beads 20. Apparatus according to claim 18 or 19, characterized in that the fractionating attachment (4) and the transfer pipe (8,9) are integrally formed with one another,