Rivista e Edizione

Volume 31 (2022): Edizione 2 (July 2022)

Volume 31 (2022): Edizione 1 (March 2022)

Volume 30 (2021): Edizione 4 (November 2021)

Volume 30 (2021): Edizione 3 (July 2021)

Volume 30 (2021): Edizione 2 (May 2021)

Volume 30 (2021): Edizione 1 (March 2021)

Volume 29 (2020): Edizione 3 (December 2020)

Volume 29 (2020): Edizione 2 (August 2020)

Volume 29 (2020): Edizione 1 (April 2020)

Volume 28 (2019): Edizione 7 (December 2019)

Volume 28 (2019): Edizione 6 (August 2019)

Volume 28 (2019): Edizione 5 (May 2019)

Volume 28 (2018): Edizione 4 (December 2018)

Volume 28 (2018): Edizione 3 (October 2018)

Volume 28 (2018): Edizione 2 (August 2018)

Volume 28 (2018): Edizione 1 (April 2018)

Volume 27 (2017): Edizione 8 (December 2017)

Volume 27 (2017): Edizione 7 (September 2017)

Volume 27 (2017): Edizione 6 (April 2017)

Volume 27 (2017): Edizione 5 (January 2017)

Volume 27 (2016): Edizione 4 (October 2016)

Volume 27 (2016): Edizione 3 (July 2016)

Volume 27 (2016): Edizione 2 (April 2016)

Volume 27 (2016): Edizione 1 (January 2016)

Volume 26 (2015): Edizione 7 (September 2015)

Volume 26 (2015): Edizione 6 (June 2015)

Volume 26 (2015): Edizione 5 (March 2015)

Volume 26 (2014): Edizione 4 (December 2014)

Volume 26 (2014): Edizione 3 (September 2014)

Volume 26 (2014): Edizione 2 (July 2014)

Volume 26 (2014): Edizione 1 (April 2014)

Volume 25 (2013): Edizione 8 (December 2013)

Volume 25 (2013): Edizione 7 (September 2013)

Volume 25 (2013): Edizione 6 (June 2013)

Volume 25 (2013): Edizione 5 (March 2013)

Volume 25 (2012): Edizione 4 (December 2012)

Volume 25 (2012): Edizione 3 (August 2012)

Volume 25 (2012): Edizione 2 (June 2012)

Volume 25 (2012): Edizione 1 (February 2012)

Volume 24 (2011): Edizione 6 (November 2011)

Volume 24 (2011): Edizione 5 (May 2011)

Volume 24 (2011): Edizione 4 (January 2011)

Volume 24 (2010): Edizione 3 (November 2010)

Volume 24 (2010): Edizione 2 (July 2010)

Volume 24 (2010): Edizione 1 (April 2010)

Volume 23 (2009): Edizione 6 (December 2009)

Volume 23 (2009): Edizione 5 (September 2009)

Volume 23 (2009): Edizione 4 (May 2009)

Volume 23 (2008): Edizione 3 (December 2008)

Volume 23 (2008): Edizione 2 (August 2008)

Volume 23 (2008): Edizione 1 (April 2008)

Volume 22 (2007): Edizione 5 (June 2007)

Volume 22 (2007): Edizione 4 (January 2007)

Volume 22 (2006): Edizione 3 (October 2006)

Volume 22 (2006): Edizione 2 (July 2006)

Volume 22 (2006): Edizione 1 (April 2006)

Volume 21 (2005): Edizione 8 (December 2005)

Volume 21 (2005): Edizione 7 (October 2005)

Volume 21 (2005): Edizione 6 (July 2005)

Volume 21 (2005): Edizione 5 (April 2005)

Volume 21 (2004): Edizione 4 (December 2004)

Volume 21 (2004): Edizione 3 (October 2004)

Volume 21 (2004): Edizione 2 (July 2004)

Volume 21 (2004): Edizione 1 (March 2004)

Volume 20 (2003): Edizione 8 (December 2003)

Volume 20 (2003): Edizione 7 (November 2003)

Volume 20 (2003): Edizione 6 (July 2003)

Volume 20 (2003): Edizione 5 (March 2003)

Volume 20 (2002): Edizione 4 (December 2002)

Volume 20 (2002): Edizione 3 (August 2002)

Volume 20 (2002): Edizione 2 (June 2002)

Volume 20 (2002): Edizione 1 (February 2002)

Volume 19 (2001): Edizione 7 (October 2001)

Volume 19 (2001): Edizione 6 (July 2001)

Volume 19 (2001): Edizione 5 (April 2001)

Volume 19 (2001): Edizione 4 (January 2001)

Volume 19 (2000): Edizione 3 (October 2000)

Volume 19 (2000): Edizione 2 (July 2000)

Volume 19 (2000): Edizione 1 (April 2000)

Volume 18 (1999): Edizione 6 (December 1999)

Volume 18 (1999): Edizione 5 (July 1999)

Volume 18 (1999): Edizione 4 (April 1999)

Volume 18 (1998): Edizione 3 (December 1998)

Volume 18 (1998): Edizione 2 (August 1998)

Volume 18 (1998): Edizione 1 (April 1998)

Volume 17 (1997): Edizione 3 (December 1997)

Volume 17 (1997): Edizione 2 (September 1997)

Volume 17 (1996): Edizione 1 (December 1996)

Volume 16 (1995): Edizione 4 (November 1995)

Volume 16 (1995): Edizione 3 (July 1995)

Volume 16 (1994): Edizione 2 (June 1994)

Volume 16 (1994): Edizione 1 (May 1994)

Volume 15 (1992): Edizione 3 (November 1992)

Volume 15 (1992): Edizione 2 (April 1992)

Volume 15 (1991): Edizione 1 (August 1991)

Volume 14 (1990): Edizione 6 (June 1990)

Volume 14 (1989): Edizione 5 (October 1989)

Volume 14 (1989): Edizione 4 (February 1989)

Volume 14 (1989): Edizione 3 (January 1989)

Volume 14 (1988): Edizione 2 (October 1988)

Volume 14 (1987): Edizione 1 (December 1987)

Volume 13 (1986): Edizione 5 (December 1986)

Volume 13 (1986): Edizione 4 (August 1986)

Volume 13 (1986): Edizione 3 (July 1986)

Volume 13 (1985): Edizione 2 (December 1985)

Volume 13 (1985): Edizione 1 (January 1985)

Volume 12 (1984): Edizione 5 (November 1984)

Volume 12 (1984): Edizione 4 (July 1984)

Volume 12 (1984): Edizione 3 (February 1984)

Volume 12 (1983): Edizione 2 (June 1983)

Volume 12 (1983): Edizione 1 (February 1983)

Volume 11 (1982): Edizione 5 (November 1982)

Volume 11 (1982): Edizione 4 (August 1982)

Volume 11 (1982): Edizione 3 (January 1982)

Volume 11 (1981): Edizione 2 (September 1981)

Volume 11 (1981): Edizione 1 (March 1981)

Volume 10 (1980): Edizione 3 (October 1980)

Volume 10 (1980): Edizione 2 (July 1980)

Volume 10 (1979): Edizione 1 (December 1979)

Volume 9 (1978): Edizione 5 (December 1978)

Volume 9 (1978): Edizione 4 (July 1978)

Volume 9 (1977): Edizione 3 (October 1977)

Volume 9 (1977): Edizione 2 (June 1977)

Volume 9 (1977): Edizione 1 (April 1977)

Volume 8 (1976): Edizione 7 (October 1976)

Volume 8 (1976): Edizione 6 (June 1976)

Volume 8 (1976): Edizione 5 (March 1976)

Volume 8 (1975): Edizione 4 (December 1975)

Volume 8 (1975): Edizione 3 (August 1975)

Volume 8 (1975): Edizione 2 (May 1975)

Volume 8 (1975): Edizione 1 (January 1975)

Volume 7 (1974): Edizione 5 (September 1974)

Volume 7 (1974): Edizione 4 (April 1974)

Volume 7 (1973): Edizione 3 (November 1973)

Volume 7 (1973): Edizione 2 (June 1973)

Volume 7 (1973): Edizione 1 (January 1973)

Volume 6 (1972): Edizione 5 (October 1972)

Volume 6 (1972): Edizione 4 (August 1972)

Volume 6 (1972): Edizione 3 (March 1972)

Volume 6 (1971): Edizione 2 (September 1971)

Volume 6 (1971): Edizione 1 (July 1971)

Volume 5 (1970): Edizione 6 (December 1970)

Volume 5 (1970): Edizione 5 (November 1970)

Volume 5 (1970): Edizione 4 (August 1970)

Volume 5 (1969): Edizione 3 (December 1969)

Volume 5 (1969): Edizione 2 (August 1969)

Volume 5 (1969): Edizione 1 (June 1969)

Volume 4 (1968): Edizione 7 (December 1968)

Volume 4 (1968): Edizione 6 (November 1968)

Volume 4 (1968): Edizione 5 (July 1968)

Volume 4 (1968): Edizione 4 (May 1968)

Volume 4 (1968): Edizione 3 (February 1968)

Volume 4 (1967): Edizione 2 (October 1967)

Volume 4 (1967): Edizione 1 (August 1967)

Volume 3 (1966): Edizione 9 (December 1966)

Volume 3 (1966): Edizione 8 (December 1966)

Volume 3 (1966): Edizione 7 (November 1966)

Volume 3 (1966): Edizione 6 (September 1966)

Volume 3 (1966): Edizione 5 (May 1966)

Volume 3 (1965): Edizione 4 (October 1965)

Volume 3 (1965): Edizione 3 (August 1965)

Volume 3 (1965): Edizione 2 (May 1965)

Volume 3 (1965): Edizione 1 (April 1965)

Volume 2 (1964): Edizione 7 (November 1964)

Volume 2 (1964): Edizione 6 (October 1964)

Volume 2 (1964): Edizione 5 (May 1964)

Volume 2 (1964): Edizione 4 (February 1964)

Volume 2 (1963): Edizione 3 (October 1963)

Volume 2 (1963): Edizione 2 (June 1963)

Volume 2 (1963): Edizione 1 (March 1963)

Volume 1 (1962): Edizione 10 (December 1962)

Volume 1 (1962): Edizione 9 (December 1962)

Volume 1 (1962): Edizione 8 (November 1962)

Volume 1 (1962): Edizione 7 (November 1962)

Volume 1 (1962): Edizione 6 (July 1962)

Volume 1 (1962): Edizione 5 (February 1962)

Volume 1 (1961): Edizione 4 (November 1961)

Volume 1 (1961): Edizione 3 (August 1961)

Volume 1 (1961): Edizione 2 (May 1961)

Volume 1 (1961): Edizione 1 (January 1961)

Dettagli della rivista
Formato
Rivista
eISSN
2719-9509
Pubblicato per la prima volta
01 Jan 1992
Periodo di pubblicazione
4 volte all'anno
Lingue
Inglese

Cerca

Volume 14 (1988): Edizione 2 (October 1988)

Dettagli della rivista
Formato
Rivista
eISSN
2719-9509
Pubblicato per la prima volta
01 Jan 1992
Periodo di pubblicazione
4 volte all'anno
Lingue
Inglese

Cerca

9 Articoli
Accesso libero

Isolation and Identification of the Wax Esters from the Cuticular Waxes of Green Tobacco Leaf

Pubblicato online: 06 Jan 2015
Pagine: 67 - 84

Astratto

Abstract

Recent studies in our laboratory on the cuticular chemicals of green tobacco leaf have revealed the presence of wax esters, composed of fatty acids bound to fatty alcohols. Cuticular components of young green NC 2326 tobacco leaves were removed with methylene chloride, and partitioned between hexane and 80 % MeOH-H2O. The hexane-soluble fraction, which contained wax esters, paraffinic hydrocarbons, and fatty alcohols, was separated by silicic acid column chromatography, and the resulting wax ester fraction was further purified by lipophilic gel chromatography. Initial analyses of the wax ester fraction by capillary gas chromatography [GC] and capillary GC / MS, on a short fused silica [FS] SE-54 capillary column, indicated the presence of C30 - C52 wax esters. Application of the cold on-column injection technique and use of immobilized stationary phase, FS SE-54 capillary columns greatly improved the GC separation of the complex wax ester fraction and permitted the identification of individual wax ester isomers. Identification of wax ester isomers by GC/MS relied upon the presence of a molecular ion and ions characteristic of the acid and alcohol moieties. For the acid portion, these ions included the acid MW + 1 a.m.u. and MW - 17 a.m.u. ions, while for the alcohol, they were the alcohol MW - 18 a.m.u. and MW + 27 a.m.u. ions. Saponification of the wax ester fraction and subsequent analyses of the alcohols (as trimethylsilyl ethers) and acids (as methyl esters) revealed extensive iso- and anteiso-methyl branching of the acid moieties. The wax ester isomers with iso- and anteiso- methyl-branched acid moieties were separated from each other and from the normal straight-chain isomers by capillary GC and were identified by GC/MS, based upon characteristic ions resulting from the losses of the iso-branched (MW - 43 a.m.u.) and anteiso-branched (MW - 57 a.m.u.) groups from the molecular ion and from the acid moiety. One hundred and seventy individual wax esters were identified.

Accesso libero

Application of Fourier Transform Infra-red Evolved Gas Analysis (FT-IR-EGA) to the Study of Tobacco Curing

Pubblicato online: 06 Jan 2015
Pagine: 85 - 91

Astratto

Abstract

FT-IR evolved gas analysis, a non-isothermal pyrolysis technique, is used to probe the changes in tobacco leaf composition which occur during flue- and air-curing. A unique perspective of major enzymatic processes and their dependencies on curing method is obtained through simultaneous detection of multiple pyrolytic products and three-dimensional presentation of the product evolution profiles. The conversion of starch to sugars, proteins to amino acids, and the relationships between these processes are explored.

Accesso libero

Pattern Recognition of Tobacco Headspace GC Profiles: A Potential New Analytical Tool for the Classification of Raw Tobaccos

Pubblicato online: 06 Jan 2015
Pagine: 93 - 103

Astratto

Abstract

The first part of the paper describes a new method of obtaining reproducible and meaningful headspace profiles of tobacco lamina by using a modified closed loop stripping apparatus. The complex chromatograms are obtained by high-resolution glass capillary gas chromatography. The second part summarizes the results of a chemometric approach to interpret the chromatograms obtained from a series of nine Virginia flue-cured tobaccos from different origins and belonging to different quality groups, each one analysed three times by the method described above. After the elimination of peaks containing redundant information, the resulting data set, consisting of 27 × 17 data points, was analysed to detect natural groupings by using an in-house program (in Basic) for principal component analysis. A subsequent discriminant analysis yielded two discriminant functions capable of separating the nine Virginia tobaccos into three quality groups as defined by a conventional organoleptic analysis carried out by a smoking panel. All the tobaccos could be classified correctly (100 %). A first attempt to classify, by the procedure described above, a group of six Virginia tobaccos whose organoleptic scores were not known, did not yield clearly interpretable results, possibly because the performance of the capillary column used for analysis had slightly deteriorated during the experiment with resultant changes in retention characteristics, which led to wrong identifications of certain peaks.

Accesso libero

Automated Tobacco Investigation Using Flow-Injection Analysis (FIA) - AutomatisierteTabakuntersuchungmittelsFliessinjektionsanalyse (FlA)

Pubblicato online: 06 Jan 2015
Pagine: 105 - 118

Astratto

Abstract

Watery tobacco extracts were examined with the aid of flow-injection analysis (FIA) for the substances nicotine, nitrate, chloride, ammonium and phosphate. The results proved to be exact and reproducible for the most part and the speed of analysis was between 37 and 113 measurements per hour. Because of its simple modular design the appliance is flexible in its application and is above all suited for the analysis for several components in small series of samples. A special FIA technique (stopped-flow method) enables the undersurface absorption stemming from the sample matrix to be excluded. The solutions used must exhibit uniform fluid composition and the formation of gas bubbles in the analysis system must be excluded.

Accesso libero

Puff Volume Measurement as affected by Temperature with Various Cigarette Types and Modes of Smoking (an in vitro study)

Pubblicato online: 06 Jan 2015
Pagine: 119 - 126

Astratto

Abstract

An in vitro evaluation was made of the measurement of puffing behaviour using an orifice-plate cigarette holder. Four brands of cigarettes were compared ranging in tar yield from 4 to 16 mg, and each was studied with two puff profiles, the “early triangle” and the “square wave” pattern. Two flow rates were used for each profile giving maximum flows of 25.7 and 37.0 ml s-1(early triangle) and 12.0 and 36.7 (square wave), respectively, and four puff volumes, i.e. 15, 40, 65, and 90 ml for each profile/flow combination. Forty-eight cigarettes of each type were smoked (three for each profile/flow/volume combination). The studies emphasize the need for careful calibration of the alinear flow system and the value of reference volume standards. When calibrated with air, volume measurements on smoke at ambient temperature were overestimated by an average of 1.4 %. An average overestimation of 1.2 % was seen per 1°C rise in temperature. This rise in temperature occurred in the last few puffs, and was mainly influenced by the puff volume. There was much less difference when subdividing the data according to cigarette type, the early triangle or square wave profiles, or the two flow rates. With puff volumes of 15 ml there was virtually no temperature rise, and except at 90 ml the effect was only important in the last 20 % of the smoking period.

Accesso libero

Evaluation of Selected Steroids as Chemical Markers of Past or Presently Occurring Fungal Infections on Tobacco

Pubblicato online: 06 Jan 2015
Pagine: 127 - 134

Astratto

Abstract

Three fungal strains isolated from tobacco were cultured on tobacco water extracts. In these cultures, the mycelium weight was shown to be correlated with the concentration of a steroid, ergosta-5,7,22-trien-3ss-ol [ergosterol]. This steroid is not a tobacco constituent, but tobacco samples where mold or yeast infections had occurred exhibited significant amounts of it. A method is proposed to quantify ergosterol in tobacco samples by reverse-phase high-performance liquid chromatography (HPLC) with UV detection at 282 nm. 7-Dehydrocholesterol can be used as internal standard. When found in a tobacco sample, the ergosterol concentration exhibits a good correlation with that of another related steroid, ergosta-4,6,8(14),22-tetraen-3-one [ETO], for which an HPLC quantification method in tobacco is proposed. Because it is highly fluorescent, ETO is also amenable to a sensitive and quick determination by thin-layer chromatography (TLC). Once produced on tobacco, ergosterol concentration remains stable through storage under normal conditions, and even primary processing does not alter it appreciably. Possible applications of ergosterol analysis to the detection of fungal infections or the monitoring of fungal growth on tobacco are outlined. In addition, TLC estimation of the ETO concentration in a sample may constitute a convenient and fast screening method for fungal infections.

Accesso libero

Obituary Jacques Flesselles

Pubblicato online: 06 Jan 2015
Pagine: 61 - 62

Astratto

Accesso libero

Obituary Charles Herbert Keith, II

Pubblicato online: 06 Jan 2015
Pagine: 63 - 63

Astratto

Accesso libero

Iain McDonald

Pubblicato online: 06 Jan 2015
Pagine: 65 - 66

Astratto

9 Articoli
Accesso libero

Isolation and Identification of the Wax Esters from the Cuticular Waxes of Green Tobacco Leaf

Pubblicato online: 06 Jan 2015
Pagine: 67 - 84

Astratto

Abstract

Recent studies in our laboratory on the cuticular chemicals of green tobacco leaf have revealed the presence of wax esters, composed of fatty acids bound to fatty alcohols. Cuticular components of young green NC 2326 tobacco leaves were removed with methylene chloride, and partitioned between hexane and 80 % MeOH-H2O. The hexane-soluble fraction, which contained wax esters, paraffinic hydrocarbons, and fatty alcohols, was separated by silicic acid column chromatography, and the resulting wax ester fraction was further purified by lipophilic gel chromatography. Initial analyses of the wax ester fraction by capillary gas chromatography [GC] and capillary GC / MS, on a short fused silica [FS] SE-54 capillary column, indicated the presence of C30 - C52 wax esters. Application of the cold on-column injection technique and use of immobilized stationary phase, FS SE-54 capillary columns greatly improved the GC separation of the complex wax ester fraction and permitted the identification of individual wax ester isomers. Identification of wax ester isomers by GC/MS relied upon the presence of a molecular ion and ions characteristic of the acid and alcohol moieties. For the acid portion, these ions included the acid MW + 1 a.m.u. and MW - 17 a.m.u. ions, while for the alcohol, they were the alcohol MW - 18 a.m.u. and MW + 27 a.m.u. ions. Saponification of the wax ester fraction and subsequent analyses of the alcohols (as trimethylsilyl ethers) and acids (as methyl esters) revealed extensive iso- and anteiso-methyl branching of the acid moieties. The wax ester isomers with iso- and anteiso- methyl-branched acid moieties were separated from each other and from the normal straight-chain isomers by capillary GC and were identified by GC/MS, based upon characteristic ions resulting from the losses of the iso-branched (MW - 43 a.m.u.) and anteiso-branched (MW - 57 a.m.u.) groups from the molecular ion and from the acid moiety. One hundred and seventy individual wax esters were identified.

Accesso libero

Application of Fourier Transform Infra-red Evolved Gas Analysis (FT-IR-EGA) to the Study of Tobacco Curing

Pubblicato online: 06 Jan 2015
Pagine: 85 - 91

Astratto

Abstract

FT-IR evolved gas analysis, a non-isothermal pyrolysis technique, is used to probe the changes in tobacco leaf composition which occur during flue- and air-curing. A unique perspective of major enzymatic processes and their dependencies on curing method is obtained through simultaneous detection of multiple pyrolytic products and three-dimensional presentation of the product evolution profiles. The conversion of starch to sugars, proteins to amino acids, and the relationships between these processes are explored.

Accesso libero

Pattern Recognition of Tobacco Headspace GC Profiles: A Potential New Analytical Tool for the Classification of Raw Tobaccos

Pubblicato online: 06 Jan 2015
Pagine: 93 - 103

Astratto

Abstract

The first part of the paper describes a new method of obtaining reproducible and meaningful headspace profiles of tobacco lamina by using a modified closed loop stripping apparatus. The complex chromatograms are obtained by high-resolution glass capillary gas chromatography. The second part summarizes the results of a chemometric approach to interpret the chromatograms obtained from a series of nine Virginia flue-cured tobaccos from different origins and belonging to different quality groups, each one analysed three times by the method described above. After the elimination of peaks containing redundant information, the resulting data set, consisting of 27 × 17 data points, was analysed to detect natural groupings by using an in-house program (in Basic) for principal component analysis. A subsequent discriminant analysis yielded two discriminant functions capable of separating the nine Virginia tobaccos into three quality groups as defined by a conventional organoleptic analysis carried out by a smoking panel. All the tobaccos could be classified correctly (100 %). A first attempt to classify, by the procedure described above, a group of six Virginia tobaccos whose organoleptic scores were not known, did not yield clearly interpretable results, possibly because the performance of the capillary column used for analysis had slightly deteriorated during the experiment with resultant changes in retention characteristics, which led to wrong identifications of certain peaks.

Accesso libero

Automated Tobacco Investigation Using Flow-Injection Analysis (FIA) - AutomatisierteTabakuntersuchungmittelsFliessinjektionsanalyse (FlA)

Pubblicato online: 06 Jan 2015
Pagine: 105 - 118

Astratto

Abstract

Watery tobacco extracts were examined with the aid of flow-injection analysis (FIA) for the substances nicotine, nitrate, chloride, ammonium and phosphate. The results proved to be exact and reproducible for the most part and the speed of analysis was between 37 and 113 measurements per hour. Because of its simple modular design the appliance is flexible in its application and is above all suited for the analysis for several components in small series of samples. A special FIA technique (stopped-flow method) enables the undersurface absorption stemming from the sample matrix to be excluded. The solutions used must exhibit uniform fluid composition and the formation of gas bubbles in the analysis system must be excluded.

Accesso libero

Puff Volume Measurement as affected by Temperature with Various Cigarette Types and Modes of Smoking (an in vitro study)

Pubblicato online: 06 Jan 2015
Pagine: 119 - 126

Astratto

Abstract

An in vitro evaluation was made of the measurement of puffing behaviour using an orifice-plate cigarette holder. Four brands of cigarettes were compared ranging in tar yield from 4 to 16 mg, and each was studied with two puff profiles, the “early triangle” and the “square wave” pattern. Two flow rates were used for each profile giving maximum flows of 25.7 and 37.0 ml s-1(early triangle) and 12.0 and 36.7 (square wave), respectively, and four puff volumes, i.e. 15, 40, 65, and 90 ml for each profile/flow combination. Forty-eight cigarettes of each type were smoked (three for each profile/flow/volume combination). The studies emphasize the need for careful calibration of the alinear flow system and the value of reference volume standards. When calibrated with air, volume measurements on smoke at ambient temperature were overestimated by an average of 1.4 %. An average overestimation of 1.2 % was seen per 1°C rise in temperature. This rise in temperature occurred in the last few puffs, and was mainly influenced by the puff volume. There was much less difference when subdividing the data according to cigarette type, the early triangle or square wave profiles, or the two flow rates. With puff volumes of 15 ml there was virtually no temperature rise, and except at 90 ml the effect was only important in the last 20 % of the smoking period.

Accesso libero

Evaluation of Selected Steroids as Chemical Markers of Past or Presently Occurring Fungal Infections on Tobacco

Pubblicato online: 06 Jan 2015
Pagine: 127 - 134

Astratto

Abstract

Three fungal strains isolated from tobacco were cultured on tobacco water extracts. In these cultures, the mycelium weight was shown to be correlated with the concentration of a steroid, ergosta-5,7,22-trien-3ss-ol [ergosterol]. This steroid is not a tobacco constituent, but tobacco samples where mold or yeast infections had occurred exhibited significant amounts of it. A method is proposed to quantify ergosterol in tobacco samples by reverse-phase high-performance liquid chromatography (HPLC) with UV detection at 282 nm. 7-Dehydrocholesterol can be used as internal standard. When found in a tobacco sample, the ergosterol concentration exhibits a good correlation with that of another related steroid, ergosta-4,6,8(14),22-tetraen-3-one [ETO], for which an HPLC quantification method in tobacco is proposed. Because it is highly fluorescent, ETO is also amenable to a sensitive and quick determination by thin-layer chromatography (TLC). Once produced on tobacco, ergosterol concentration remains stable through storage under normal conditions, and even primary processing does not alter it appreciably. Possible applications of ergosterol analysis to the detection of fungal infections or the monitoring of fungal growth on tobacco are outlined. In addition, TLC estimation of the ETO concentration in a sample may constitute a convenient and fast screening method for fungal infections.

Accesso libero

Obituary Jacques Flesselles

Pubblicato online: 06 Jan 2015
Pagine: 61 - 62

Astratto

Accesso libero

Obituary Charles Herbert Keith, II

Pubblicato online: 06 Jan 2015
Pagine: 63 - 63

Astratto

Accesso libero

Iain McDonald

Pubblicato online: 06 Jan 2015
Pagine: 65 - 66

Astratto

Pianifica la tua conferenza remota con Sciendo