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Aroma compounds in Airen and Macabeo musts and wines were submitted to multivariate analysis of variance and only those significantly depending (p < 0.05) on grape variety, prefermentative treatment, and exhibiting no significant interaction were selected for discriminant analysis. Benzyl alcohol, Z-3-hexen-1-ol, hexanoic acid, benzaldehyde, β-ionone, and E-nerolidol contents in musts were used to calculate 2 discriminating functions, which allow classifying 100% of all must by variety and treatment. Discriminant analysis carried out with 1-propanol, isoamyl alcohol, 2-phenylethanol, ethyl acetate, ethyl propanoate, ethyl lactate, isobutyl acetate, and 7-butyrolactone contents in wines, allows to establish 2 other functions, which led to accurate classification of 100% of the wine samples.

International audience; This article presents a model of beer fermentation in terms of flavor component content. It describes the production of two higher alcohols (isoamyl alcohol and phenyl ethanol) and three esters (isoamyl acetate, ethyl acetate, and ethyl hexanoate) selected according to their organolep-tic threshold values in beer, as well as the effects of operating conditions on their formation. A step-by-step modeling approach was used, which exploited prior biological information coupled with analysis of experimental data. These data resulted from a two-level full-factorial experimental design for three factors: temperature (10–16°C), top pressure (50– 800 mbar), and yeast inoculum (0.5 × 10 7 –2 × 10 7 cells per milliliter). Experiments were carried out in a 15-L reactor. Because CO 2 emission, which represented the only on-line measurement in this process, is directly associated with primary yeast activity, the aroma dynamics were predicted from those for CO 2 , with yield coefficients depending only on operating conditions (temperature, dissolved CO 2 , yeast inoculum size). Model parameters were identified from experimental data. An initial experimental validation gives a successful prediction of most of the aroma compounds when compared with their measured values. The model quantifies the effects of operating conditions on the production kinetics and final concentrations of aroma compounds. These results suggest that this model could be successfully used for both prediction and co ntrol of some aroma compounds under industrial conditions.; Este artículo presenta un modelo de la fermentación de cerveza basado en el contenido de determinados compuestos que contribuyen a su sabor. Describe la producción de dos alcoholes superiores (alcohol isoamílico y fenil-etanol) y de tres ésteres (acetato de isoamilo, acetato de etilo y hexanoato de etilo) seleccionados en función de los valores umbrales de su percepción organoléptica, así como de los efectos que las condiciones operativas tienen sobre su formación. Hemos utilizado un modelo por pasos que hace uso de la información biológica disponible a priori, junto con el análisis de los datos experimentales. Dichos datos dieron lugar a un diseño experimental en el que se consideraron tres factores a dos niveles y en todas las combinaciones posibles: temperatura (10-16°C), máxima presión (50-800 mbar) e inóculo de levadura (0,5 x 10 7-2 x 10 7 células por mililitro). Los experimentos se llevaron a cabo en un reactor de 15 litros. Debido a que las medidas de producción de CO 2 (que suponen las únicas medidas del proceso efectuadas en línea) están directamente relacionadas con la actividad primaria de la levadura, la dinámica de la formación de aromas se predijo a partir de la de CO 2 , aplicando coeficientes de rendimiento que dependían exclusivamente de las condiciones de operación del proceso (temperatura, CO 2 disuelto, tamaño del inóculo de levadura). Los parámetros del modelo se identificaron a partir de los datos experimentales. Un experimento inicial de validación predijo correctamente muchos de los compuestos aromáticos en comparación con los valores medidos para los mismos. El modelo proporciona valores cuantitativos de los efectos de las condiciones de operación del proceso sobre las cinéticas de producción y las concentraciones finales de los compuestos aromáticos. Estos resultados sugieren que este modelo puede ser utilizado con éxito en condiciones industriales, tanto para la predicción como para el control de determinados compuestos aromáticos.

DNA isolation is a process used for isolation of DNA from different types of samples using a combination of physical and chemical methods. A comparative study is made to isolate DNA from 30 teeth samples with some pre PCR and post PCR modifications in the organic Phenol: Chloroform: isoamyl alcohol, Automate ExpressTM prepfiler BTA kit and QIAamp® DNA Investigator Kit. Our result showed significant results which will be helpful in short listing the array of these techniques.

Three solid-liquid separation techniques, vacuum filtration, centrifugation, and settling, were used prior to fermentation to clarify musts from two different white grape varieties (Vitis vinifera var. Parellada and Macabeo) on an industrial scale. Solid content and ammonium and amino acid concentrations were analyzed before and after clarification, and sugar, ethanol, glycerol, n-propyl alcohol, isoamyl alcohol, and ethyl acetate compositions were monitored during the fermentations to determine how the clarification treatment affected the fermentation rate and higher alcohol production. The results show that vacuum filtration gives musts with the lowest solid content, and this means longer fermentation time, lower isoamyl alcohol production, and greater ethyl acetate formation. However, the three industrial clarification techniques studied caused no significant differences in the initial amount of ammonium nitrogen and total free amino acids.

International audience; Iso-amyl alcohol (iso-pentanol or 3-methylbutan-1-ol) that can be biologically produced is among the possible alcohols usable as alternative fuel in internal combustion engines. It has a higher energy density than smaller alcohols (ca. 28.5MJ/L compared to ca. 21 for ethanol, and 27 for 1-butanol); it is less hydroscopic than ethanol and mix better with hydrocarbons. In order to better understand the combustion characteristics of that alcohol, new experimental data were obtained for its kinetic of oxidation in a jet-stirred reactor (JSR). Concentration profiles of stable species were measured in a JSR at 10 atm over a range of equivalence ratios (0.35-4) and temperatures (530-1220 K). The oxidation of iso-pentanol was modeled using an extended detailed chemical kinetic reaction mechanism (2065 reactions involving 343 species) derived from a previously proposed scheme for the oxidation of a variety of fuels. The proposed mechanism shows good agreement with the present experimental data. Reaction path and sensitivity analyses were conducted for interpreting the results.

Hydrogenation of 4,4′-dipyridyl or 4-(4-piperidyl)pyridine with sodium in isoamyl alcohol gives a mixture of hydro derivatives, from which 4-(4-piperidyl)-1,2,5,6-tetrahydropyridine was isolated.

The production of the acetates of isoamyl alcohol and phenethyl alcohol and the ethyl esters of the C6-C10 fatty acids was investigated in semiaerobic sugar fermentations by 56 strains of Saccharomyces cerevisiae and 3 strains of S. uvarum. The S. cerevisiae yeasts generally produced more esters than the S. uvarum yeasts. Isoamyl acetate was the main component in the ester fractions examined and others in decreasing order, were ethyl caprylate, ethyl caproate, ethyl caprate and phenethyl acetate.

A GLC method was developed for the measurement of steady-state levels of amitriptyline and nortriptyline in human plasma after therapeutic doses of amitriptyline. The drugs were extracted from alkalinized samples with heptane-3% isoamyl alcohol and back-extracted into 0.1 N HCl. After subsequent extraction into ether, the drugs were analyzed by GLC. The method is accurate, specific, and sensitive, being capable of measuring concentrations as low as 25 ng/ml of these drugs. After 6 days of amitriptyline administration (75 mg/day), levels of amitriptyline and nortriptyline in three subjects were approximately 40–90 and 40 ng/ml, respectively, 12 hr after the last dose.

The polymerization of acrylonitrile in aqueous media initiated by peroxydisulphate-isoamyl alcohol(IAA) redox pair catalyzed by silver ion was studied at low conversion. The polymerization had kinetic orders 1.5 with respect to monomer, 0.6 (peroxydisulphate) and 0.5 (silver ion). The reactions were carried out at various temperatures and the overall activation energy was found to be 5.5 kcal/mol. The effect of certain water-miscible organic solvents was also investigated. A mechanism of initiation is tentatively proposed.

A bathophenanthroline method was examined to determine microamounts of iron in water. Investigations were made with artificial standards of ferrous diammonium sulfate solution. Analytical procedure was similar to the Wilson's method [found in Analyst, 89, 389 (1964)] but pH adjustment was made with a glass-electrode pH-meter. Ferrous-bathophenanthroline complex was stable in isoamyl alcohol for more than twenty hours. Determinations could be available within the errors 0.4 μg/l (95% confidence limits). This value is smaller than that of authorized in JIS B 8224(1961).

EXAMINATION of the leaves of a series of grasses in the usual way1, which involves hydrolysing the leaves in 2 normal hydrochloric acid and extracting the hydrolysate with isoamyl alcohol, showed in four of them the presence of a component giving rise to a scarlet-coloured anthocyanidin having an Rf of 0.62 in Forestal solvent (acetic acid : concentrated hydrochloric acid : water, 30 : 3 : 10 by volume). The extract, diluted with methanol, had λmax between, 496 and 502 nm, indicating its probable identity with luteolinidin (Rf 0.62 in Forestal, λmax in, methanol 496 nm (ref. 2)). It thus seems that the four grasses contain a leucoluteolinidin. It is unlikely that such a compound could have a flavan-3,4-diol structure, but the flavan-4-ol (4,5,7,3′,4′-pentahydroxyflavan) produced by reduction of eriodictyol with sodium borohydride (unpublished results of T. Swain) and a methanolic extract of the grasses behaved identically both when boiled with 2 normal hydrochloric acid (yielding luteolinidin) and when treated with cold concentrated hydrochloric acid. In the latter case a blue colour was produced with λmax 550 nm, the product responsible being, perhaps, the carbonium ion of the ring-opened form of the flavan3. On standing, or after dilution and heating, this was partially converted into luteolinidin. It should be noted that other flavan-4-ols show similar behaviour3, but flavan-3,4-diols (for example, leucocyanidin), although giving an intermediate blue–purple component when heated in 2 normal hydrochloric acid, do not give such a colour with cold concentrated acid.

A few years ago one of the authors in unpublished results showed that rhodamine-B would precipitate pepsin from solution. Since the well known proteolytic ferment precipitating agent, safranine, also precipitates insulin,1 it was decided to determine if rhodamine-B would precipitate insulin and if so, whether the dye could be removed without inactivation of the insulin. Our experimental results show that insulin is readily precipitated by rhodamine-B at pH 7.2. The complex is soluble in distinctly acid solution, probably with decomposition into its components, for the dye can be practically completely removed by extraction with isoamyl alcohol, leaving the insulin behind in the aqueous layer.To 1 cc of insulin, Lilly, (40 units per cc) 1 cc of a phosphate buffer solution of pH 7.2 was added, followed by 1 cc of a saturated solution of technical rhodamine-B which was either centrifuged or allowed to stand for several days to remove water insoluble impurities. Almost immediately after addition of the dye a ...

An extraction-spectrophotometric procedure for the determination of manganese(II) based on the formation of a chelate with 3-phenyl-2-mercaptopropenoic acid is described. The 1:2 manganese complex is quantitatively extracted into isoamyl alcohol (2-methylbutan-1-ol) in the pH range 6.3–9.4. The extract shows maximum absorbance at 625 nm (Iµ= 7.3 × 103 l mol–1 cm–1) and obeys Beer's law up to 20 µg ml–1 of manganese. The method is selective and has been applied successfully to the determination of manganese in standard samples.

A method for the determination of molybdenum in natural waters in the micrograms per millilitre range is proposed. The method involves the preconcentration of molybdenum on a Chelex-100 chelating resin and subsequent elution with ammonia solution, followed by extraction with a complexing reagent, 1,4-dihydroxyphthalimide dithiosemicarbazone dissolved in NN-dimethylformamide - isoamyl alcohol (1 + 4), and a final direct determination by atomic-absorption spectrometry. The addition of ascorbic acid prior to extraction eliminates the interfering effect of several ions at the concentration levels normally found in natural waters. The sensitivity of the method is 0.3 µg 1–1 for 1% absorption. The method has been applied to the determination of molybdenum in sea and surface waters.

The Gerber fat test was carried out on milk samples preserved with potassium dichromate in the concentration range of 0.05-1.50%.No difference in Gerber fat values was found between the samples which were added with potassium dichromate in the concentration of 0.05-0.15% and the sample without addition of potassium dichromate. However, the Gerber fat values were considerably and remarkably increased with the addition in the concentration of 0.20% and 0.25%, respectively.In view of the Gas chromatography investigation on constituents of the fat layer developed in the graduated tube of butyrometer, it seems most reasonable to conclude that the fat soluble products from isoamyl alcohol, oxidized by potassium dichromate caused the apparent increase of the fat values.A modification method that isoamyl alcohol was added to butyrometer after the warming of the reaction mixture of sample and sulfuric acid for 10min. rewarmed for 5min. at 60-65°C, and centrifuged was presented to avoid the apparent increase of the fat value.

The synthesis, characteristics and analytical applications of 3-(4-methoxyphenyl)-2-mercaptopropenoic acid (4MF2MP) are described. A highly sensitive, selective and rapid spectrophotometric method is described for the determination of trace amounts of nickel by 3-(4-methoxyphenyl)-2-mercaptopropenoic acid. This compound reacts instantaneously with Ni(II) in alkaline media to produce a yellow complex (1:2) soluble in water (λmax.= 400 nm, Iµ= 1.95 × 104 l mol–1 cm–1) that can be extracted quantitatively with isoamyl alcohol (λmax.= 410 nm, Iµ= 9.5 × 103 l mol–1 cm–1) and octanol (λmax.= 415 nm, Iµ= 1.9 × 104 l mol–1 cm–1). This method has been applied to the determination of nickel in hydrogenated greases, steels and solders. The results are compared with those obtained using dimethyl glyoxime.

N-Phenyllaurohydroxamic acid reacts with titanium(IV) in 9–10 M hydrochloric acid to give a complex that is completely extractable into solvents such as hexane and chloroform. The chloroform extract of the titanium complex, on second extraction from a dilute hydrochloric acid medium (0.1–0.5 M), in the presence of phenylfluorone and isoamyl alcohol, forms an intensely coloured complex possessing an absorption maximum at 540 nm. Even though the molar absorptivity of the complex under optimum conditions at 540 nm is 2.33 × 105 l mol–1 cm–1, the measurements are more precise at 560 nm with a molar absorptivity of 1.23 × 105 l mol–1 cm–1. The system obeys Beer's law for up to 0.4 p.p.m. of titanium (IV). Considerable amounts of many cations and anions including a 350-fold molar excess of iron(III) can be tolerated. Interference from zirconium(IV) can be mitigated or even eliminated by the addition of fluoride ions. The method can be applied to the determination of titanium present at 10 parts per 109.

A sensitive and selective method for the micro-determination of titanium, based on the direct measurement of light absorption by a liquid ion exchanger phase that has absorbed the coloured complex species derived from the sample, has been developed. The sensitivity of the titanium(IV)-benzohydroxamic acid (BHA) complex extracted with a liquid ion exchanger, Aliquat 336, in the presence of thiocyanate is ten times greater than that of the titanium(IV)-BHA complex extracted with hexanol or isoamyl alcohol. The method can be applied to the concentration, determination and separation of titanium(IV) in industrial effluents and environmental samples containing very low levels of the metal.

Equilibrium constants have been obtained for the distribution of sulphuric acid between aqueous solutions and isoamyl alcohol solutions of di- and tri-(3,5,5-trimethylhexyl)amines forming the normal amine sulphates and the amine bisulphates. The extraction follows a simple equilibrium law using a solvent for the amines (isoamyl alcohol) in which it has also been shown that no aggregation phenomenon of the amine salts occurs.

THE nitronium ion, NO2 +, has been shown to be the active nitrating entity in the O-nitration of certain alcohols in organic solvents1 in which nitric acid is present in large excess. Kinetic studies in progress on the esterification of isoamyl alcohol with nitric acid in 55–62 per cent aqueous perchloric acid have now indicated that here also O-nitration proceeds through the nitronium ion, although only a very small fraction of the nitric acid can be present in this cationic form in media of such high water-content. Rate measurements at 25° C. made by ultra-violet spectrometric analysis of the unchanged nitric acid after dilution of aliquots with water and extraction of the isoamayl nitrate product show that the rate equation (1) is obeyed