Alcohol determination using analyzers

Molecular diffusion ( ) has been used in various ways in micro analysis. In Figure 27, is seen the Conway diffusion dish, in which the substance to be tested is placed on the outside, and the reagent is placed in the central cup. The cup is covered, and after a time, the substance being analyzed diffuses into the central cup where it produces an effect which can then be interpreted in various ways. In the Figure, carbon monoxide is being determined. This same method is very useful for alcohol determination, where dichromate oxidizes the alcohol after it diffuses into the dichromate from the blood. 

In theory the fermentation could be followed equally satisfactorily by measuring the alcohol content of the solution. In fact, however, alcohol determinations are much slower and more complicated than density determinations, so they are seldom, if ever, used. It is possible for the fermentation to stop—successive density determinations showing the same value—while there is some sugar left in the solution, although this is not normal behavior for fermentations. It is good practice to analyze for low levels of sugars in all wines when they have apparently completed their fermentations. 

New instruments for determining blood alcohol concentration use IR spectroscopy for analyzing the C-H absorption of CH3CH2OH in exhaled air (compare Figure 12.10 for a description of an earlier method). 

Several commercial evidential breath alcohol measurement devices are available. The principle of measurement is either infrared absorption spectrometry (most common), dichromate-sulfuric acid oxidation-reduction (photometric), GC (flame ionization or thermal conductivity detection), electrochemical oxidation (fuel cell), or metal-oxide semiconductor sensors. A list has been published of DOT-approved breath alcohol devices.Some of these devices are approved for screening only. In this case, the second or confirmatory breath alcohol determination must be performed with an approved evidential breath alcohol analyzer. Breath alcohol devices may also be used for the medical evaluation of patients at the point of care (e.g., emergency department). A Fourier transform infrared point-of-care breath analyzer capable of measurement of... 

Alcohol determinations at the roadside or at home are typically done with a breath analyzer or breathalyzer. Because of rapid gas exchange and the vapor pressure of ethanol, the concentration exhaled is directly related to the blood alcohol concentration. The blood alcohol concentration is widely used as a criterion for determining whether a person is under the influence of alcohol. Many states have ruled that a blood alcohol level of 0.1% or greater indicates intoxication. 

Mixed vapors of acrolein and ethyl alcohol were passed over the catalyst in a heated stainless steel tube at atmospheric pressure. Products were condensed and fractionated in a 20-plate bubble tray column. Fractions taken were acetaldehyde, 20-36°, and acrolein-ethyl alcohol, 36-78.4°. At this point water was added to the distillation kettle and an ethyl alcohol-aUyl alcohol-water fraction, 78-95°, was taken overhead. Fractions were analyzed for aldehydes by the hydroxylamine hydrochloride method, for im-saturation by reaction with bromine in aqueous potassium bromide, for alcohol by the nitrite ester method, and for water with Fischer reagent. Propyl alcohol in the water-free allyl alcohol recovered from the azeotrope was calculated by difference from the total alcohol determined by reaction with acetyl chloride and the unsaturated alcohol determined by reaction with aqueous bromine solution. Fresh catalyst was used for each experiment. 

Twenty-four samples of four European virgin olive oil varieties Arbequina, Coratina, Koroneiki, and Picual, cultivated in Greece, Italy, and Spain-were analyzed for their chemical composition. Non-volatile compounds (31) fatty acids, sterols, alcohols, and methylsterols and volatile ones (65) aldehydes, alcohols, furans, hydrocarbons, acids, ketones, and esters were determined using GC and DHS-GC-MS methods, respectively. ... 

Alcohols are also analyzed by LC in most cases the choice of the column falls on an ionic-exchange resin of the styrene-divinyl benzene polymer type, to which has been linked a functional group of the sulfonic type in the form or with another suitable cation. Since the separation of alcohols is performed very often together with other analytes, such as organic acids and sugars, the choice of the type of detector also takes into account their chemical-physical properties. Usually, the choice is the UV detector, the refractive index detector, or the electrochemical detector (EC). The use of LC allows the determination of less volatile alcohols such as glycerol in wine and beer, which could be difficult to analyze by GC. 

Polyoxyethylene oleyl ethers, POE(5), POE(IO) and POE(20) were kindly supplied by NOF CO., LTD. POE(5), POE(IO), and POE(20) were synthesized from high-purity oleyl alcohol (99.7%). The mean number of oxyethylene unit, which was determined by analyzing end hydroxyl group [4], are 5.1 for POE(5), 10.7 for POE(IO) and 19.2 for POE(20), respectively. The trace of oleyl alcohol was detected by high-performance liquid chromatography, but the distribution of number of oxyethylene unit(n) in POE(n) is narrow. Doubly distilled water was used. 

Blood and urine are most often analyzed for alcohol by headspace gas chromatography (qv) using an internal standard, eg, 1-propanol. Assays are straightforward and lend themselves to automation (see Automated instrumentation). Urine samples are collected as a voided specimen, ie, subjects must void their bladders, wait about 20 minutes, and then provide the urine sample. Voided urine samples provide the most accurate deterrnination of blood alcohol concentrations. Voided urine alcohol concentrations are divided by a factor of 1.3 to determine the equivalent blood alcohol concentration. The 1.3 value is used because urine has approximately one-third more water in it than blood and, at equiUbrium, there is about one-third more alcohol in the urine as in the blood. 

High performance Hquid chromatography (hplc) may be used to determine nitroparaffins by utilizing a standard uv detector at 254 nm. This method is particularly appHcable to small amounts of nitroparaffins present, eg, in nitro alcohols (qv), which caimot be analyzed easily by gas chromatography. Suitable methods for monitoring and deterrnination of airborne nitromethane, nitroethane, and 2-nitropropane have been pubUshed by the National Institute of Occupational Safety and Health (NIOSH) (97). Ordinary sorbant tubes containing charcoal are unsatisfactory, because the nitroparaffins decompose on it unless the tubes are held in dry ice and analyzed as soon after collection as possible. 

Raki, a Turkish alcoholic drink was also analyzed by differential pulse polarography and copper, iron and zinc could be determined. For the arsenic content in beer a more sensitive method had to be applied. For this method a new catalytic method is established and the arsenic content was determined by using this new method. 

Other detection methods are based on optical transmittance [228-231], Alcohol sulfates have been determined by spectrophotometric titration with barium chloride in aqueous acetone at pH 3 and an indicator [232] or by titration with Septonex (carbethoxypentadecyltrimethylammonium bromide) and neutral red as indicator at pH 8.2-8.4 and 540 nm [233]. In a modified two-phase back-titration method, the anionic surfactant solution is treated with hyamine solution, methylene blue, and chloroform and then titrated with standard sodium dodecyl sulfate. The chloroform passing through a porous PTFE membrane is circulated through a spectrometer and the surfactant is analyzed by determining the absorbance at 655 nm [234]. The use of a stirred titration vessel combined with spectrophotometric measurement has also been suggested [235]. Alternative endpoint detections are based on physical methods, such as stalag-mometry [236] and nonfaradaic potentiometry [237]. 

The alkyl chain distribution of the base alcohol in alcohol sulfates is easily determined by gas chromatography. However, alcohol sulfates and alcohol ether sulfates are not volatile and require a previous hydrolysis to yield the free alcohol. The extracted free alcohol can be injected directly [306] or converted to its trimethylsilyl derivative before injection [307]. Alternatively, the alcohol sulfate can be decomposed by hydroiodic acid to yield the alkyl iodides of the starting alcohols [308]. A preferred method forms the alkyl iodides after hydrolysis of the alcohol sulfate which are analyzed after further extraction of the free alcohol, thus avoiding the formation of hydrogen sulfide. This latter method is commonly used to determine the alkyl chain distribution of alcohol ether sulfates. 

The content of the products of lipid peroxidation (LPO) was determined after 1 h of incubation of the cells in a buffer A at 37 °C. Aliquot of cell suspension (100 pg protein) was treated with heptane/isopropyl alcohol mixture at the ratio of 1 1. The content of Schiff bases in heptane phase was analyzed on fluorimeter RF-510, Shimadzu (Japan) at iexit = 360 nm and Xgms = 420 nm (Kolesova et al., 1984). The content of diene conjugates was determined by spectrophotometry (Gavrilov et al., 1988) at the wavelength of X = 245 nm using spectrophotometer Scinco (Germany). 

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